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IMAGE DISPLAY DEVICE AND IMAGE GENERATING DEVICE
BACKGROUND
[0001]
5 The present disclosure relates to an image display device and an image
generating device, and more particularly to an image display device suitable for use
in a head mounted display (HMD), and an image generating device suitable for use
in the image display device.
[0002]
10 A virtual display device (image display device) for allowing an observer to
observe a two-dimensional (2D) image formed by an image generating device as a
virtual image enlarged by a virtual image optical system is well known, for example,
from Japanese Patent Application Publication No. 2006-162767.
[0003]
15 As illustrated in a conceptual diagram of FIG 26, an image display device
1100 includes an image generating device 111 having a plurality of pixels arranged in
a 2D matrix, a collimating optical system 112, which collimates light output from a
pixel of the image generating device 111 into parallel light, and a light guide unit 120
on which the parallel light from the collimating optical system 112 is incident,
20 through which the light is guided, and from which the light is output. The light
guide unit 120 includes a light guide plate 121, which outputs the incident light after
the incident light propagates through the inside according to total reflection, a first
deflecting unit 130 (for example, including a light reflecting film of one layer),
which reflects the light incident on the light guide plate 121 so that the light incident
25 on the light guide plate 121 is totally reflected inside the light guide plate 121, and a
second deflecting unit 140 (for example, including a light reflecting multi-film
having a multi-layer laminated structure), which outputs from the light guide plate
121 the light propagating through the inside of the light guide plate 121 according to
the total reflection. A weight and size of a device can be reduced, for example,
30 when the HMD is formed according to such an image display device 1100.
[0004]
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Alternatively, in order to allow an observer to observe a 2D image formed
by the image generating device as a virtual image enlarged by the virtual image
optical system, a virtual image display device (image display device) using hologram
diffraction gratings is well known, for example, from Japanese Patent Application
5 Publication No. 2007-094175.
[0005]
As illustrated in a conceptual diagram of FIG 27, an image display device
1300 basically includes an image generating device 111, which displays an image, a
collimating optical system 112, and a light guide unit 320 on which light displayed
10 on the image generating device 111 is incident and through which the incident light
is guided to a pupil 21 of the observer. Here, the light guide unit 320 includes a
light guide plate 321 and a first diffraction grating member 330 and a second
diffraction grating member 340 formed by reflective volume hologram diffraction
gratings provided on the light guide plate 321. Light output from each pixel of the
15 image generating device 111 is incident on the collimating optical system 112, and
parallel light is generated by the collimating optical system 112 and incident on the
light guide plate 321. The parallel light is incident on and output from a first
surface 322 of the light guide plate 321. On the other hand, the first diffraction
grating member 330 and the second diffraction grating member 340 are mounted on
20 a second surface 323 of the light guide plate 321 parallel to the first surface 322 of
the light guide plate 321.
SUMMARY
[0007]
25 The light output from the image generating device 111 becomes a group of
parallel fluxes having different view angles (that is, output angles of light beams
output from pixels of the image generating device 111) in the collimating optical
system 112 on an XY plane illustrated in FIG. 27. The parallel flux group becomes
a group of light fluxes having different view angles in an XZ plane orthogonal
30 thereto, and is incident on the light guide plate 321. In FIG 27, representative
parallel light fluxes in the XY plane are indicated as parallel light flux rl (indicated
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by a solid line), r2 (indicated by a dashed-dotted line) and r3 (indicated by a dotted
line). In FIG 28, representative parallel light fluxes in the :xz plane are indicated
as parallel light flux RI (indicated by a solid line), R2 (indicated by a dashed-dotted
line) and R3 (indicated by a dotted line). In the illustrated image display device
5 1300, a left-right (horizontal) direction is set as a Y direction and an up-down
(vertical) direction is set as a Z direction. That is, light for displaying a video,
various types of information, and the like is guided from a lateral direction with
respect to the pupil 21 ofthe observer, and incident on the pupil 21.
[0008]
10 Incidentally, in this configuration, there are problems as will be described
later due to a difference in behavior of parallel light flux in the XY plane of light
guided through the inside ofthe light guide plate 321 and parallel light flux in the :xz
plane. FIG 29A is a diagram illustrating a problem in the image display device of
the related art, and FIG 29B is a diagram schematically illustrating a propagation
15 state of light output from a center portion and an upper portion of the collimating
optical system and guided through the light guide plate. FIG 29A is a diagram
schematically illustrating a propagation state of light, which is output from the image
generating device and guided through the light guide unit, and reaches the pupil,
within a plane corresponding to an inside ofthe :xz plane and the XY plane.
20 [0009]
That is, in the above-described configuration, light incident from the first
surface 322 of the light guide plate 321 is incident on the first diffraction grating
member 330 disposed on the second surface 323. A distance from the center of the
collimating optical system 112 to the center of the first diffraction grating member
25 330 is set as LJ, a distance from the center of the first diffraction grating member 330
to the center of the second diffraction grating member 340 is set as L2, and a distance
from the second diffraction grating member 340 to the pupil 21 is set as L3.
[0010]
In terms of an X direction component ofthe XY plane, the light fluxes rl, r2,
30 and r3 are diffracted and reflected by the first diffraction grating member 330, are
guided inside the light guide plate 321 while being iteratively totally reflected
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between the first surface 322 and the second surface 323 in a state of parallel light
fluxes, and move in a Y direction toward the second diffraction grating member 340
provided on the other end of the light guide plate 321. Parallel light of each view
angle incident on the second diffraction grating member 340 is output from the light
5 guide plate 321 under a total reflection condition according to diffraction reflection
and incident on the pupil 21 of the observer. Here, in a travelling direction of the
parallel light fluxes, the number of reflections within the light guide plate 321 differs
according to a view angle. That is, an optical path length is different. However,
because all light fluxes to propagate are parallel light fluxes, a light flux group moves
10 to be folded. Accordingly, in terms of light of an X direction component of the XY
plane, a substantial distance from the center of the collimating optical system 112 to
the pupil 21 becomes (Ll+L3) because the distance L2 from the center of the first
diffraction grating member 330 to the center of the second diffraction grating
member 340 can be neglected. In addition, this system can be generally regarded as
15 a telecentric optical system, and a position of the first diffraction grating member 330
becomes an exit pupil position in terms of light of the X direction component of the
XYplane.
[0011]
On the other hand, although the X direction component is iteratively
20 reflected within the light guide plate 321 in terms of incident light beams RJ, R2, and
R3 in the XZ plane, a Z direction component reaches the second diffraction grating
member 340 without being reflected. That is, light output from the collimating
optical system 112 converges in the XZ plane to be incident from the first surface
322 and moves in the Y direction inside the light guide plate 321. These light
25 fluxes move while being reflected by the first surface 322 and the second surface 323
of the light guide plate 321 so that the light fluxes are narrow in the Z direction, and
reach the second diffraction grating member 340. The light fluxes are reflected,
diffracted, and output by the second diffraction grating member 340 and incident on
the pupil 21 of the observer. That is, in terms of light of the Z direction component
30 of the XZ plane, a substantial distance from the center of the collimating optical
system 112 to the pupil 21 generally becomes (L1+L2/sin( as illustrated in FIG. 1. In addition, in terms of light of the Z
direction component of the XZ plane in a non-telecentric optical system, a position
5 of the pupil 21 or a position in the vicinity of the pupil 21 becomes an exit pupil
position.
[0012]
Therefore, although light of a spatial region having diagonal lines from the
top right to the bottom left reaches the pupil 21, for example, in terms of incident
10 light R3', as illustrated in FIG. 29A, light of a spatial region having diagonal lines
from the top left to the bottom right does not reach the pupil 21. That is, part of
light flux does not reach the pupil 21, and a type of vignetting occurs. In other
words, there are problems that the utilization efficiency of light output from the
image generating device 111 is low and that the low utilization efficiency of light
15 leads to an increase in power consumption in the image generating device 111.
[0013]
For example, as is well known from Japanese Patent Application Publication
No. 10-170859, an image display device displays an image on a display surface
formed by a plurality of pixels of an image generating unit, guides light flux output
20 from the image transmitted and illuminated by an illuminating unit to the pupil ofthe
observer via an optical system, and allows the observer to view a virtual image of the
image formed by the light flux. In this image display device, light flux output from
each pixel is incident on the optical system as light flux of a divergence angle
different between a first direction and a second direction by setting the first direction
25 and the second direction substantially orthogonal to the first direction within a plane
on which the virtual image is formed and controlling divergence angles of the first
direction and the second direction using a divergence angle conversion unit provided
in the vicinity of each pixel for every pixel. However, it is difficult to solve a
problem that the utilization efficiency of light is low even when light flux of a
30 divergence angle different between the first direction and the second direction is
incident on the optical system as described above.
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[0014]
It is desirable to provide an image display device having a configuration and
structure that can improve the utilization efficiency of light output from the image
generating device and further reduce power consumption in an image generating
5 device and an image generating device suitable for use in the image display device.
[0015]
In accordance with an embodiment of the present disclosure, there is
provided an image display device including:
(A) an image generating device; and
10 (B) a light guide unit on which light from the image generating device is
incident, through which the light is guided, and from which the light is output toward
a pupil of an observer.
[0016]
The image generating device of the present disclosure has the light guide
15 unit, which includes
a light guide plate from which the incident light is output after the incident
light propagates through an inside according to total reflection,
a first deflecting unit configured to deflect the light incident on the light
guide plate so that the light incident on the light guide plate is totally reflected inside
20 the light guide plate, and
a second deflecting unit configured to deflect the light propagating through
the inside of the light guide plate according to the total reflection a plurality of times
so that the light propagating through the inside of the light guide plate according to
the total reflection is output from the light guide plate. The term ''total reflection"
25 unit internal total reflection or total reflection inside the light guide plate.
Hereinafter, the same is also true.
[0017]
In the image display device of the present disclosure or the image
generating device of the present disclosure, when a point at which light output from a
30 center of the image generating device is incident on the light guide unit is set as a
point 0, a normal line passing through the point °in a portion of the light guide unit
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is set as an X axis, an axis of the light guide unit passing through the point 0 in a
portion ofthe light guide unit is set as a Y axis, an optical axis of light incident at the
point 0 of the light guide unit among light beams output from a center of the image
generating device is set as a Saxis, and a virtual plane including the Saxis and the Y
5 axis is set as a sY plane, light output from the image generating device and incident
at a point (0, YI, ZI) ofthe light guide unit forms an angle 8z with the sYplane and
forms an angle 8y with an XZ plane. When Zr;t:O, 8Z';t:8y is satisfied.
[0018]
In the image display device or the image generating device of the present
10 disclosure, when Zr;t:O, 8z:;t:8y is satisfied. Accordingly, part of light flux output
from the light guide unit does not reach the pupil, the occurrence of a phenomenon
that a type of vignetting occurs can be suppressed, and the utilization efficiency of
light output from the image generating device can be improved. Consequently,
power consumption in the image generating device can be reduced.
15
BRIEF DESCRIPTION OF THE ORAWINGS
[0019]
FIG 1 is a conceptual diagram of an image display device of Embodiment
1·,
20 FIGS. 2A and 2B are diagrams schematically illustrating a propagation state
of light when viewed from an XZ plane and a propagation state of light when viewed
from an XY plane among light beams output from a light emitting unit positioned in
an upper portion of an image generating device of Embodiment 1;
FIGS. 3A and 3B are diagrams schematically illustrating a propagation state
25 of light when viewed from the XZ plane and a propagation state of light when
viewed from the XY plane among light beams output from a light emitting unit
positioned in a center portion ofthe image generating device of Embodiment 1;
FIG 4A is a diagram schematically illustrating a propagation state of light,
which is output from the image generating device of Embodiment 1 and guided
30 through a light guide unit, and reaches a pupil, within a plane corresponding to an
inside ofthe XZ plane and the XY plane;
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FIG 4B is a diagram schematically illustrating light output from each light
emitting unit of the image generating device;
FIGS. 4C and 4D are diagrams illustrating a relationship between the light
guide unit and a central incident light beam when the light guide unit is viewed from
5 the side;
FIG 5 is a schematic diagram of the image display device of Embodiment 1
viewed from above;
FIG 6 is a schematic diagram of the image display device of Embodiment 1
viewed from the side;
10 FIG 7 is a schematic diagram of the image display device of Embodiment 1
viewed from the front;
FIG 8 is a diagram illustrating a state in which the image display device of
Embodiment 1 is mounted on a head of an observer viewed from above (only the
image display device is illustrated and the illustration ofthe frame is omitted);
15 FIG 9 is a conceptual diagram of an image display device of Embodiment
2;
FIGS. lOA and lOB are conceptual diagrams of an image display device of
Embodiment 3;
FIG 11 is a conceptual diagram of an image display device of Embodiment
20
25
30
FIG 12 is a schematic diagram of an image display device of Embodiment 5
viewed from the side;
FIG 13 is a schematic diagram of an image display device of Embodiment 6
viewed from the front;
FIG 14 is a schematic diagram of an image display device of Embodiment 6
viewed from above;
FIG 15 is a schematic diagram of an HMD of Embodiment 7 viewed from
the front;
FIG 16 is a schematic diagram of an HMD of Embodiment 7 (in a state in
which a frame is assumed to be removed) viewed from the front;
FIG 17 is a schematic diagram of the HMD of Embodiment 7 viewed from
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above;
FIG 18 is a schematic diagram of an HMD of Embodiment 8 viewed from
the front;
FIG 19 is a schematic diagram of the HMD of Embodiment 8 (in a state in
5 which a frame is assumed to be removed) viewed from the front;
FIG 20 is a schematic diagram of the HMD of Embodiment 8 viewed from
above;
FIG 21 is a conceptual diagram of a modified example of an image
generating device suitable for use in Embodiment 1 or 3;
10 FIG 22 is a conceptual diagram illustrating another modified example ofthe
image generating device suitable for use in Embodiment 1 or 3;
FIG 23 is a conceptual diagram illustrating still another modified example
of the image generating device suitable for use in Embodiment 1 or 3;
FIG 24 is a conceptual diagram illustrating still another modified example
15 of the image generating device suitable for use in Embodiment 1 or 3;
FIG 25 is a conceptual diagram illustrating still another modified example
of the image generating device suitable for use in Embodiment 1 or 3;
FIG 26 is a conceptual diagram of an image display device of the related
art;
20 FIG 27 is a conceptual diagram of the image display device of the related
art having another form different from that illustrated in FIG 26;
FIG 28 is a conceptual diagram of the image display device of the related
art of the form illustrated in FIG 27 viewed from another direction;
FIG 29A is a diagram illustrating a problem in the image display device of
25 the related art;
FIG 29B is a diagram schematically illustrating a propagation state of light
that is output from a center portion and an upper portion of a collimating optical
system and guided through a light guide plate; and
FIG 30 is a schematic diagram of a form of image display device of the
30 related art viewed from the side.
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DETAILED DESCRIPTION OF THE EMBODIMENT(S)
[0020]
Hereinafter, although the present disclosure will be described based on
embodiments with reference to the drawings, the present disclosure is not limited to
5 the embodiments, and various numerical values and materials mentioned in the
embodiments are exemplary. Description will be given in the following order.
1. Overall Description of Image Display Device and Image Generating
Device of Present Disclosure
2. Embodiment 1 (Image Display Device and Image Generating Device:
10 First Form ofImage Generating Device/First Form of Light Guide Unit)
3. Embodiment 2 (Modification of Embodiment 1: Second Form of Image
Generating Device/First Form of Light Guide Unit)
4. Embodiment 3 (Modification of Embodiment 1: First Form of Image
Generating Device/Second Form of Light Guide Unit)
15 5. Embodiment 4 (Modification of Embodiment 1: Second Form of Image
Generating Device/Second Form ofLight Guide Unit)
6. Embodiment 5 (Modification of Embodiments 1 to 4)
7. Embodiment 6 (Other Modification of Embodiments 1 to 4)
8. Embodiment 7 (Modification of Embodiments 1 to 6)
20 9. Embodiment 8 (Modification of Embodiment 7) and Others
[0021]
[Overall Description of Image Display Device and Image Generating
Device ofPresent Disclosure]
In the image display device or image generating device of the present
25 disclosure (hereinafter, these may be collectively referred to as the "image display
device and the like ofthe present disclosure"),
a value ofey is constant regardless ofa value ofYI, and
an absolute value of ez can be increased when an absolute value of Z\ is
increased. In the image display device or the like of the present disclosure of a
30 preferred form as described above, the absolute value of ez can be formed to be
increased monotonically or stepwise when the absolute value of Z\ is increased.
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Although 8y is not specifically limited when the value of 8y is constant regardless of
the value ofYI, it is only necessary that, for example, 8y = O.
[0022]
Further, the image display device and the like of the present disclosure of
5 these forms can have a configuration in which:
the image generating device has a light emitting unit (light output unit)
disposed in a 2D matrix,
a microlens array in which a plurality of microlenses are arranged in a 2D
matrix is disposed in the image generating device,
10 light output from each light emitting unit is output from the image
generating device through a microlens facing the light emitting unit, and
shift amounts of an optical axis of the light emitting unit and an optical axis
of the microlens facing the light emitting unit are defined based on a value of (0, VI,
ZI). In this case, although the microlens is not limited, the microlens can be formed
15 by a cylindrical lens or an anamorphic lens. In addition, in these cases, a radiation
angle (divergence angle) COl of light output from the microlens can be configured to
be less than a radiation angle (divergence angle) COD of light output from the light
emitting unit.
[0023]
20 Alternatively, the image display device and the like of the present disclosure
of a preferred form as described above can have a configuration in which:
an image generating device is provided with a light output angle control
member, and
light is output from the image generating device to a light guide unit through
25 the light output angle control member. In this case, there is provided a
configuration in which:
the image generating device has light emitting units (light output units)
arranged in a 2D matrix,
the light output angle control member is formed by a microlens array in
30 which a plurality of microlenses are arranged in a 2D matrix, and
light output from each light emitting unit is output from the image
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generating device through a microlens facing the light emitting unit. Further, in this
case, shift amounts of an optical axis of the light emitting unit and an optical axis of
the microlens facing the light emitting unit can be configured to be defined based on
a value of (0, V), ZI). In these configurations, although the microlens is not limited,
5 the microlens can be formed by a cylindrical lens or an anamorphic lens. A
radiation angle (divergence angle) 0)1 of light output from the microlens can be
configured to be less than a radiation angle (divergence angle) 0)0 of light output
from the light emitting unit.
[0024]
10 The microlens or microlens array can be manufactured through a wellknown
method. In addition, the optical axis of the microlens can be configured to
be inclined based on a value of (0, YI, ZI) instead of shifting the optical axis of the
light emitting unit and the optical axis of the microlens facing the light emitting unit
based on the value of (0, V), Zl). In this case, it is only necessary to appropriately
15 design a curvature factor of a light output plane ofthe microlens.
[0025]
Further, in the image display device of the present disclosure including a
preferred form and configuration as described above, the light guide unit can include:
(B-1) a light guide plate from which the incident light is output after the
20 incident light propagates through an inside according to total reflection,
(B-2) a first deflecting unit configured to deflect the light incident on the
light guide plate so that the light incident on the light guide plate is totally reflected
inside the light guide plate, and
(B-3) a second deflecting unit configured to deflect the light propagating
25 through the inside of the light guide plate according to the total reflection a plurality
of times so that the light propagating through the inside of the light guide plate
according to the total reflection is output from the light guide plate.
[0026]
Further, in the image display device and the like of the present disclosure
30 including a preferred form and configuration as described above, for example, a
liquid crystal display (LCD) device, an organic electro luminescence (EL) display
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device, an inorganic EL display device, or a light emitting element array in which a
plurality of light emitting elements are arranged in a 2D matrix can be included as
the image generating device. In this image display device, the image generating
device can further include a parallel light outputting optical system formed by a
5 collimating optical system that collimates light output from each light emitting unit
(a pixel or a virtual pixel) and passing through the microlens array or the light output
angle control member into parallel light, and light from the parallel light outputting
optical system (collimating optical system) can be configured to be incident on the
light guide unit. For convenience, this image generating device is referred to as the
10 "first form of image generating device."
[0027]
Alternatively, the image generating device includes
a light source,
a collimating optical system, which collimates light output from the light
15 source into parallel light,
a scanning unit, which scans the parallel light output from the collimating
optical system, and
a parallel light outputting optical system formed by a relay optical system,
which relays the parallel light scanned by the scanning unit,
20 wherein light output from the scanning unit and passing through a microlens
array or a light output angle control member can be configured to be incident on the
parallel light outputting optical system (relay optical system) and light from the
parallel light outputting optical system (relay optical system) can be configured to be
incident on the light guide unit. For convenience, this image generating device is
25 referred to as the "second form of image generating device." Light output from the
scanning unit (optical points) is arranged in a 2D matrix in a space, and each optical
point corresponds to a light emitting unit (a virtual pixel).
[0028]
In addition, for example, an image generating device including a reflective
30 spatial light modulating device and a light source; an imaging generating device
including a transmissive spatial light modulating device and a light source; and an
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image generating device formed by a light emitting element array including light
emitting elements such as an organic EL, an inorganic EL, and light emitting diodes
(LEDs) can be included as the image generating device in the first form of image
generating device. A light valve, for example, a transmissive or reflective LCD
5 device such as liquid crystal on silicon (LCOS) or a digital micromirror device
(DMD), can be included as the spatial light modulating device, and a light emitting
element can be included as the light source. Further, the reflective spatial light
modulating device can be formed by an LCD device and a polarization beam splitter
that reflects part of light from the light source to guide the reflected part of the light
10 to the LCD device and passes part of light reflected by the LCD device to guide the
part of the light to the parallel light emitting optical system. As the light emitting
element constituting the light source, a red light emitting element, a green light
emitting element, a blue light emitting element, and a white light emitting element
can be included. Alternatively, white light may be obtained by mixing red, green,
15 and blue light beams output from the red light emitting element, the green light
emitting element, and the blue light emitting element using the light pipe and
performing luminance equalization. As the light emitting element constituting the
light emitting element array, for example, there are examples of a semiconductor
laser element, a solid-state laser, and an LED. The number of light emitting units
20 (pixels or virtual pixels) may be determined based on specifications necessary for the
image display device. As a specific value of the number of light emitting units,
there are examples of 320x240, 432x240, 640x480, 854x480, 1024x768, and
1920x 1080. As the parallel light outputting optical system (collimating optical
system), there is an example of an optical system having positive optical power as a
25 whole using a convex lens, a concave lens, a free-form surface prism, and a
hologram lens independently or in combination. A light shielding member having
an opening portion to prevent undesired light from being output from the parallel
light outputting optical system may be disposed between the parallel light outputting
optical system (the collimating optical system or relay optical system) and the light
30 guide unit.
[0029]
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On the other hand, a light emitting element can be included as a light source
in the second form of image generating device, and specifically include a red light
emitting element, a green light emitting element, a blue light emitting element, and a
white light emitting element. Alternatively, white light may be obtained by mixing
5 red, green, and blue light beams output from the red light emitting element, the green
light emitting element, and the blue light emitting element using the light pipe and
performing luminance equalization. As the light emitting element, for example,
there are examples of a semiconductor laser element, a solid-state laser, and an LED.
In the second form of imaging generating device, the number of light emitting units
10 (virtual pixels) may be determined based on specifications necessary for the image
display device. As a specific value of the number of light emitting units (virtual
pixels), there are examples of320x240, 432x240, 640x480, 854x480, 1024x768, and
1920x 1080. In addition, when the light source includes the red light emitting
element, the green light emitting element, and the blue light emitting element, it is
15 preferable to perform color synthesis, for example, using a cross prism. As the
scanning unit, for example, a micro electro mechanical system (MEMS), which has a
micro mirror rotatable in a 2D direction to horizontally and vertically scan light
output from the light source, or a galvano mirror can be included. It is only
necessary to form the relay optical system constituting the parallel light outputting
20 optical system by a well-known relay optical system.
[0030]
There are examples of the following configurations in addition to a
combination of a backlight that emits white light as a whole, for example, as an
image generating device or a light source including a light emitting element and a
25 light valve, and an LCD device having a red light emitting pixel, a green light
emitting pixel, and a blue light emitting pixel.
[0031]
[Image Generating Device A]
The image generating device A includes:
30 (a) a first image generating device formed by a first light emitting panel in
which first light emitting elements for emitting blue light are arranged in a 20 matrix,
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(13) a second image generating device formed by a second light emitting
panel in which second light emitting elements for emitting green light are arranged in
a2D matrix,
(y) a third image generating device formed by a third light emitting panel in
5 which third light emitting elements for emitting red light are arranged in a 2D matrix,
and
(8) a unit (for example, a dichroic prism, which is also substantially the
same as in the following description) for integrating light output from the first,
second, and third image generating devices into one optical path,
10 wherein a light emitting/non-light-emitting state of each of the first, second,
and third light emitting elements is controlled.
[0032]
[Image Generating Device B]
The image generating device B includes:
15 (a) a first image generating device formed by a first light emitting element
for emitting blue light and a first light passage control device (which is a type of light
valve, and, for example, formed by an LCD device, a DMD, or an LCOS, which is
substantially the same as in the following description) for controlling passage/nonpassage
of the light output from the first light emitting element for emitting the blue
20 light,
(/3) a second image generating device formed by a second light emitting
element for emitting green light and a second light passage control device (light
valve) for controlling passage/non-passage of the light output from the second light
emitting element for emitting the green light,
25 (y) a third image generating device formed by a third light emitting element
for emitting red light and a third light passage control device (light valve) for
controlling passage/non-passage of the light output from the third light emitting
element for emitting the red light, and
(8) a unit for integrating light passing through the first, second, and third
30 light passage control devices into one optical path,
wherein an image is displayed by controlling passage/non-passage of the
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light output from the light emitting elements using the light passage control devices.
As a unit (light guide member) for guiding the light output from the first, second, and
third light emitting elements to the light passage control device, there are examples
of a light guide member, a microlens array, a mirror, a reflecting plate, and a
5 condensing lens.
[0033]
[Image Generating Device C]
The image generating device C includes:
(a) a first image generating device formed by a first light emitting panel in
10 which first light emitting elements for emitting blue light are arranged in a 2D matrix
and a blue light passage control device (light valve) for controlling passage/nonpassage
of the output light output from the first light emitting element for emitting
the blue light,
(~) a second image generating device formed by a second light emitting
15 panel in which second light emitting elements for emitting green light are arranged in
a 2D matrix and a green light passage control device (light valve) for controlling
passage/non-passage of the output light .output from the second light emitting panel,
(y) a third image generating device formed by a third light emitting panel in
which third light emitting elements for emitting red light are arranged in a 2D matrix
20 and a red light passage control device (light valve) for controlling passage/nonpassage
ofthe output light output from the third light emitting panel, and
(8) a unit for integrating light passing through the blue, green, and red light
passage control devices into one optical path,
wherein an image is displayed by controlling passage/non-passage of the
25 output light output from the first, second, and third light emitting panels using the
light passage control devices (light valves).
[0034]
[Image Generating Device D]
The image generating device D is a field sequential color-display image
30 generating device, and includes:
(a) a first image generating device having a first light emitting element for
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emitting blue light,
(r3) a second image generating device having a third light emitting element
for emitting green light,
(y) a third image generating device having a second light emitting element
5 for emitting red light,
(0) a unit for integrating light output from the first, second, and third image
generating devices into one optical path, and
(8) a light passage control device (light valve) for controlling passage/nonpassage
of light output from the unit for integration into the one optical path,
10 wherein an image is displayed by controlling passage/non-passage of the
light output from the light emitting elements using the light passage control devices.
[0035]
[Image Generating Device E]
The image generating device E is also a field sequential color-display image
15 generating device, and includes:
(a) a first image generating device formed by a first light emitting panel in
which first light emitting elements for emitting blue light are arranged in a 2D matrix,
(r3) a second image generating device formed by a second light emitting
panel in which second light emitting elements for emitting green light are arranged in
20 a 2D matrix,
(y) a third image generating device formed by a third light emitting panel in
which third light emitting elements for emitting red light are arranged in a 2D matrix,
(0) a unit for integrating light output from the first, second, and third image
generating devices into one optical path, and
25 (8) a light passage control device (light valve) for controlling passage/nonpassage
of light output from the unit for integration into the one optical path,
wherein an image is displayed by controlling passage/non-passage of the
light output from the light emitting panels using the light passage control device.
[0036]
30 [Image Generating Device F]
The image generating device F is a passive or active matrix type of colorSP345165XXOO
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display image generating device, which displays an image by controlling a lightemitting/
non-light-emitting state of each of first, second, and third light emitting
elements.
[0037]
5 [Image Generating Device G]
The image generating device G is a field sequential color-display image
generating device, which includes a light passage control device (light valve) for
controlling passage/non-passage of light output from light emitting element units
arranged in a 2D matrix, and displays an image by controlling a light-emitting/non-
10 light-emitting state of each of first, second, and third light emitting elements in the
light emitting element units in time division, and further controlling passage/nonpassage
of light output from the first, second, and third light emitting elements using
the light passage control device.
[0038]
15 Light, which is output from a center of the image generating device, passes
through a nodal point of the image generating device of the parallel light emitting
optical system, and is incident on the light guide unit, is referred to as a "central
incident light beam." The central incident light beam is incident at a point 0 of the
light guide unit. The point 0 may be referred to as the center point of the light
20 guide unit. As described above, an axial line that passes through the center point of
the light guide unit and is parallel to an axial direction of the light guide unit is set as
a Y axis and an axial line that passes through the center point of the light guide unit
and is consistent with a normal line ofthe light guide unit is set as an X axis.
[0039]
25 A first deflecting unit can be configured to reflect light incident on the light
guide plate, and a second deflecting unit can be configured to transmit and reflect
light propagating through the inside of the light guide plate according to the total
reflection a plurality of times. In this case, the first deflecting unit can be
configured to function as a reflecting mirror, and the second deflecting unit can be
30 configured to function as a semi-transmissive mirror. For convenience, this light
guide unit is referred to as the "first form of light guide unit."
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[0040]
In this configuration, the first deflecting unit can include a light reflecting
film (a type of mirror), which is formed of a metal including an alloy and reflects
light incident on the light guide plate or a diffraction grating (for example, a
5 hologram diffraction grating film) that diffracts the light incident on the light guide
plate. In addition, the second deflecting unit can include a multi-layer laminated
structure in which a plurality of dielectric laminated films are laminated, a semitransmissive
mirror, a polarization beam splitter, or a hologram diffraction grating
film. Although the first or second deflecting unit is disposed inside the light guide
10 plate (embedded inside the light guide plate), parallel light incident on the light guide
plate is reflected or diffracted so that the parallel light incident on the light guide
plate is totally reflected inside the light guide plate in the first deflecting unit. On
the other hand, in the second deflecting unit, the parallel light propagating through
the inside of the light guide plate according to the total reflection is reflected or
15 diffracted a plurality of times, and output from the light guide plate in a state of
parallel light.
[0041]
Alternatively, the first deflecting unit can be configured to diffract light
incident on the light guide plate, and the second deflecting unit can be configured to
20 diffract light propagating through the inside of the light guide plate according to the
total reflection a plurality of times. For convenience, this light guide unit is referred
to as the "second form of light guide unit." In this case, the first deflecting unit and
the second deflecting unit can be formed by diffraction grating elements. Further,
the diffraction grating element can be formed by a reflective diffraction grating
25 element or a transmissive diffraction grating element. Alternatively, one diffraction
grating element can be formed by the reflective diffraction grating element and the
other diffraction grating element can be formed by the transmissive diffraction
grating element. A reflective volume hologram diffraction grating can be included
as the reflective diffraction grating element. For convenience, the first deflecting
30 unit formed by the reflective volume hologram diffraction grating may be referred to
as a "first diffraction grating member," and the second deflecting unit formed by the
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reflective volume hologram diffraction grating may be referred to as a "second
diffraction grating member." That is, the diffraction direction is the Y direction and
interference fringes extend in the Z direction.
[0042]
5 The image display device in accordance with the present disclosure can
perform a single-color (for example, green) image display. When color image
display is performed, P diffraction grating layers, each of which is formed by a
reflective volume hologram diffraction grating, can be laminated to cause the first
diffraction grating member or the second diffraction grating member to cope with
10 diffraction/reflection of P types of light having P types (for example, P=3, that is,
three types of red, green, and blue) of different wavelength bands (or wavelengths).
Each diffraction grating layer is provided with interference fringes corresponding to
one type of wavelength band (or wavelength). Alternatively, to cope with
diffraction and reflection of P types of light having P types of different wavelength
15 bands (or wavelengths), P types of interference fringes can be configured to be
formed in the first diffraction grating member or the second diffraction grating
member formed by one diffraction grating layer. Alternatively, for example, the
angle of view can be divided into three equal parts, and the first diffraction grating
member or the second diffraction grating member can be configured by laminating
20 diffraction grating layers corresponding to angles of view. By adopting these
configurations, it is possible to increase the diffraction efficiency and acceptable
diffraction angle and optimize the diffraction angle when light beams having the
wavelength bands (or wavelengths) are diffracted and reflected by the first
diffraction grating member or the second diffraction grating member.
25 [0043]
The first diffraction grating member and the second diffraction grating
member can be formed of a photopolymer material. It is only necessary that the
material and basic structure of the first diffraction grating member and the second
diffraction grating member formed by the reflective volume hologram diffraction
30 gratings be the same as those of the reflective volume hologram diffraction gratings
of the related art. The reflective volume hologram diffraction grating refers to a
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hologram diffraction grating that diffracts and reflects only +I-order diffracted light.
Although the diffraction grating member is provided with interference fringes
extending from the inner side to the outer side of the diffraction grating member, a
method of forming the interference fringes may be the same as adopted in the related
5 art. Specifically, for example, it is only necessary that a material (e.g., a
photopolymer material) constituting the diffraction grating member be irradiated
with object light in a first predetermined direction on one side, a material constituting
the diffraction grating member be simultaneously irradiated with reference light in a
second predetermined direction on the other side, and interference fringes formed by
10 the object light and the reference light be recorded in the material constituting the
diffraction grating member. By appropriately selecting the first predetermined
direction, the second predetermined direction, and wavelengths of the object light
and the reference light, a desired pitch of the interference fringes and a desired slant
angle of the interference fringes on the surfaces of the diffraction grating member
15 can be obtained. The slant angle of the interference fringes refers to the angle
formed between the surfaces of the diffraction grating member (or the diffraction
grating layer) and the interference fringes. When the first diffraction grating
member and the second diffraction grating member are formed by a laminated
structure in which P diffraction grating layers, each of which is formed by a
20 reflective volume hologram diffraction grating, are laminated, it is only necessary to
separately manufacture P diffraction grating layers and then laminate (adhere) the P
diffraction grating layers, for example, using an ultraviolet curing resin adhesive.
In addition, the P diffraction grating layers may be formed by manufacturing one
diffraction grating layer using an adhesive photopolymer material, and then adhering
25 layers of the adhesive photopolymer material thereon in order to manufacture
diffraction grating layers.
[0044]
Alternatively, in the image display device in accordance with the present
disclosure, the light guide unit can be formed by a semi-transmissive mirror on
30 which light output from the image generating device is incident and from which the
incident light is reflected and output toward the pupil ofthe observer. A structure in
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which the light output from the image generating device propagates through the air
and is incident on the semi-transmissive mirror may be provided. For example, a
structure in which the light output from the image generating device propagates
inside a transparent member such as a glass plate or a plastic plate (specifically, a
5 member formed of the same material as the material constituting the light guide plate
to be described later) and incident on a semi-transmissive mirror may be provided.
The semi-transmissive mirror may be mounted on the image generating device via
the transparent member, and the semi-transmissive mirror may be mounted on the
image generating device via a member separate from the transparent member.
10 [0045]
In the first or second form of image display device, a plurality of parallel
light beams formed by the parallel light outputting optical system including the
collimating optical system or the relay optical system are incident on the light guide
plate. The requirement for parallel light beams is based on the fact that it is
15 necessary to store light wave-front information obtained when the light beams are
incident on the light guide plate even after the light beams are output from the light
guide plate via the first deflecting unit and the second deflecting unit. To generate a
plurality of parallel light beams, specifically, for example, it is only necessary that
the light output unit of the image generating device be positioned in a place
20 (position) of the focal length of the parallel light emitting optical system. The
parallel light outputting optical system has a function of converting position
information of pixels or virtual pixels into angle information in the light guide unit.
[0046]
In the image display device, the light guide plate has two parallel surfaces
25 (first and second surfaces) extending in parallel to a light propagation direction (Y
direction) according to internal total reflection of the light guide plate. When a
surface of the light guide plate on which light is incident is an incidence surface of
the light guide plate and a surface of the light guide plate from which light is output
is an output surface ofthe light guide plate, both the incidence surface and the output
30 surface of the light guide plate may be defined by the first surface, or the incidence
surface of the light guide plate may be defined by the first surface and the output
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surface ofthe light guide plate may be defined by the second surface.
[0047]
For example, the light guide plate can be formed of a glass material
including optical glass such as quartz glass or BK7, or a plastic material (e.g., poly
5 methyl methacrylate (PMMA), a polycarbonate resin, an acrylic resin, amorphous
polypropylene resin, or a styrene resin including acrylonitrile styrene (AS) resin).
The shape ofthe light guide plate is not limited to a flat plate, but may be curved.
[0048]
According to the image display device of the present disclosure, for
10 example, an HMD can be configured, a weight and size ofthe device can be reduced,
the discomfort when the device is mounted can be significantly reduced, and
manufacturing cost can be reduced.
[0049]
The HMD includes:
15 (a) an eyeglass type frame to be mounted on an observer's head, and
(b) the image display device of the present disclosure. According to the
HMD, the number of image display devices of the present disclosure may be one
(monocular type) or two (binocular type). The light guide unit can be a semitransmissive
type (see-through type). Specifically, at least a portion of the light
20 guide unit facing pupils (both eyes) of an observer is configured to be semitransmissive
(see-through), so that the outside scene can be viewed through the
portion ofthe light guide unit.
[0050]
A frame is formed by a front portion arranged on the front side of the
25 observer, two temple portions pivotably mounted on both ends of the front portion
via hinges, and an ear bend portion mounted on the tip end portion of each temple
portion, and further includes nose pads. When the entire HMD is seen, an assembly
of the frame and the nose pads has a structure that is substantially the same as that of
ordinary glasses, except that there is no rim. The material constituting the frame
30 may be a metal, alloy, or plastic, or a combination thereof and may be the same
material as the material constituting ordinary glasses. The nose pads may also have
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a well-known configuration and structure.
[0051]
From the viewpoint of design of the HMD or ease of wearing the HMD, it is
preferable that wirings (signal lines, power lines, or the like) from one or two image
5 generating devices be formed to extend from the tip end portion of the ear bend
portion to the outside via the temple portion and the inside of the ear bend portion
and to be connected to the control device (a control unit or a control circuit).
Further, it is preferable to configure a form in which each image generating device
includes a headphone unit, and a wiring for the headphone unit from each image
10 generating device extends from the tip end portion of the ear bend portion to the
headphone unit via the temple portion and the inside of the ear bend portion.
Examples of the headphone unit are an inner-ear type of headphone unit and a canal
type of headphone unit. More specifically, it is preferable to configure a form in
which the wiring for the headphone unit from the tip end portion of the ear bend
15 portion wraps around the rear side ofthe auricle (auditory capsule) and extends to the
headphone unit.
[0052]
In addition, in the HMD, an imaging device can be formed to be mounted
on a center portion of the front portion. Specifically, the imaging device is formed
20 by a solid-state imaging device, for example, formed by a CCD or a CMOS sensor
and a lens. It is only necessary that a wiring extending from the imaging device be
connected to one image display device, for example, through the back of the front
portion and further included in a wiring extending from the image display device.
[0053]
25 There is no limitation in the image display device in accordance with the
present disclosure, and a central incident light beam can be configured to intersect
the XY plane at an angle (9zo:;t:0 degrees) other than zero degrees, that is, an
incidence angle 9zo for the XY plane (an XV plane incidence angle) can be
configured to be 9zo*O degrees. Accordingly, the limitation on the mounting angle
30 of the image display device at the time of mounting of the image display device on a
mounting portion of the eyeglass type frame can be reduced, and a high degree of
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freedom for design can be obtained. When the XY plane is assumed to be
consistent with the horizontal plane, the angle 8zo at which the central incident light
beam intersects the XY plane can be configured to be an elevation angle. That is,
the central incident light beam may be configured to collide with the XY plane from
5 the lower side ofthe XY plane toward the XY plane. In such a case, it is preferable
that the XY plane intersect the vertical surface at an angle other than zero degrees,
and it is more preferable that the XY plane intersect the vertical surface at an angle
8zo'. Although the maximum value of the angle 8zo' is not limited, the maximum
value can include 5 degrees. Here, the horizontal plane includes a line of sight
10 (horizontal line of sight of an observer) when the observer views a target (for
example, a target located at an infinite distance or the horizon) located in the
horizontal direction and is a plane in which the two horizontally positioned pupils of
the observer are included. In addition, the vertical plane is a plane perpendicular to
the horizontal plane. Alternatively, the central incident light beams output from the
15 light guide unit and incident on the pupils of the observer can be formed to form a
depression angle when the observer views a target (for example, a target located at an
infinite distance or the horizon) located in the horizontal direction. The depression
angle for the horizontal plane, for example, can be in the range of 5 degrees to 45
degrees.
20 [0054]
Where the HMD is the binocular type, it is preferable that the light guide
unit further include:
a connecting member, which is disposed on the side of the center of the
observer's face as a whole rather than the image generating device and interconnects
25 the two image display devices,
wherein the connecting member is mounted on a side facing the observer in
a center portion of a frame located between the two pupils ofthe observer, and
wherein a projected image of the connecting member is included in a
projected image of the frame.
30 [0055]
As described above, according to a structure in which the connecting
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member is mounted on the center portion ofthe frame located between the observer's
two pupils, that is, when a structure in which the image display devices are directly
mounted on the frame is not provided, a displacement (positional change) of the
image generating device or the light guide unit is not caused by deformation of the
5 frame even when the temple portions are expanded to the outside when the frame is
mounted on the observer's head and hence the frame is deformed, or such
displacement, if any, is very small. Therefore, it is possible to reliably prevent
angles of convergence of left and right images from being changed. Moreover,
because it is unnecessary to enhance the rigidity of the front portion ofthe frame, it is
10 possible to avoid causing an increase in the weight of the frame, a decrease in design
quality, or an increase in cost. In addition, because the image display devices are
not directly mounted on the eyeglass type frame, the design, color and the like of the
frame can be freely selected according to the observer's preference, there are few
restrictions imposed on the design of the frame, so that the degree of freedom on a
15 design basis is high. In addition, the connecting member is disposed between the
observer and the frame, and moreover, the projected image of the connecting
member is included in the projected image of the frame. In other words, the
connecting member is hidden behind the frame when the HMD is viewed from the
front side of the observer. Accordingly, high design quality can be given to the
20 HMD.
[0056]
It is preferable to mount the connecting member on a side facing the
observer in a center portion of the front portion (corresponding to a portion of a
bridge in an ordinary pair of eyeglasses) located between the two pupils of the
25 observer.
[0057]
Although the two image display devices are connected by the connecting
member, the image generating devices can be specifically formed to be mounted on
both end portions of the connecting member, respectively, so that the mounting state
30 is adjustable. In this case, it is preferable that each of the image generating devices
be located outside the observer's pupil. In such a configuration, further, it is
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desirable that the condition of 0.0 1xL:::;u:::;0.30xL, preferably, 0.05xL:::;u:::;0.25xL, the
condition of 0.35xL:::;f3:::;O.65 xL, preferably, 0.45xL:::;f3:::;0.55xL, and the condition of
0.70xL:::;y:::;0.99xL, preferably 0.75 xL:::;y:::;0.95 xL, be satisfied, where u is the
distance between the mounting-portion center of the image generating device on one
5 side and one end portion (one wraparound end piece) of the frame, f3 is the distance
from the center of the connecting member to the one end portion (one end piece) of
the frame, y is the distance between the mounting-portion center of the image
generating device on the other side and the one end portion (one end piece) of the
frame, and L is the length of the frame. For the mounting of the image generating
10 devices on both end portions ofthe connecting member, specifically, for example, the
connecting member is provided with through-holes at three positions in each of the
end portions thereof, the image generating devices are each provided with screwengagement
portions corresponding to the through-holes, and screws are passed
through the through-holes and engaged with the screw-engagement portions provided
15 in the image generating devices. A spring is inserted between each screw and the
screw-engagement portion. The mounting state of the image generating device (the
inclination of the image generating device relative to the connecting member) can be
adjusted according to the fastening state of each ofthe screws.
[0058]
20 Here, the mounting-portion center of the image generating device is a
bisection point along an axial direction of the frame in an overlapping area in which
the projected image of the image generating device obtained upon projection of the
image generating device and the frame onto a virtual plane overlaps the projected
image of the frame in a state in which the image generating device is mounted on the
25 connecting member. In addition, the center of the connecting member is a bisection
point along the axial direction of the frame in a portion in which the connecting
member is in contact with the frame in a state in which the connecting member is
mounted on the frame. The length of the frame is the length of the projected image
of the frame when the frame is curved. The direction of projection is set as a
30 direction perpendicular to the observer's face.
[0059]
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Alternatively, although the two image display devices are connected by the
connecting member, the two light guide units can also be specifically formed to be
connected by the connecting member. The two light guide units are manufactured
in an integrated manner, and in such a case, the connecting member is mounted on
5 the light guide unit manufactured in the integrated manner, but this form is also
included in the form in which the connecting member connects the two light guide
units. Where the distance between the center of the image generating device on one
side and one end portion ofthe frame is a' and the distance between the center ofthe
image generating device on the other side and the one end portion of the frame is y',
10 it is desirable that the values of a' and y' also be substantially the same as the abovedescribed
values of a and y. The center of the image generating device is a
bisection point along the axial direction of the frame in a portion in which the
projected image of the image generating device obtained upon projection of the
image generating device and the frame onto a virtual plane overlaps the projected
15 image of the frame in a state in which the image generating device is mounted on the
light guide unit.
[0060]
The shape of the connecting member is basically freely settable insofar as
the projected image of the connecting member is included in the projected image of
20 the frame, and, for example, can include a rod shape and an elongated plate shape.
Also, examples of the material for forming the connecting member include metals,
alloys, plastics, and combinations thereof.
[Embodiment 1]
[0061]
25 Embodiment 1 relates to an image display device and an image generating
device of the present disclosure. Specifically, the image display device of
Embodiment 1 includes the first form of image generating device/first form of light
guide unit. Although a conceptual diagram of the image display device of
Embodiment 1 is illustrated in FIG. 1, the image display device of Embodiment 1 is
30 embedded in the HMD. In addition, a propagation state of light when viewed from
an XZ plane and a propagation state of light when viewed from an XY plane among
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light beams output from a light emitting unit positioned in an upper portion of an
image generating device of Embodiment 1 are schematically illustrated in FIGS. 2A
and 2B. A propagation state of light when viewed from the XZ plane and a
propagation state of light when viewed from the XY plane among light beams output
5 from a light emitting unit positioned in a center portion of the image generating
device of Embodiment 1 are schematically illustrated in FIGS. 3A and 3B. A
propagation state of light, which is output from the image generating device of
Embodiment 1 and guided through a light guide unit, and reaches a pupil, within a
plane corresponding to an inside of the XZ plane is schematically illustrated in FIG
10 4A. Light output from each light emitting unit of the image generating device is
schematically illustrated in FIG. 4B. Diagrams illustrating a relationship between
the light guide unit and a central incident light beam when the light guide unit is
viewed from the side are illustrated in FIGS. 4C and 4D. Further, a schematic
diagram of the image display device viewed from above is illustrated in FIG. 5. A
15 schematic diagram of the image display device viewed from the side is illustrated in
FIG. 6. A schematic diagram of the image display device of Embodiment 1 viewed
from the front is illustrated in FIG. 7. A diagram illustrating a state in which the
image display device of Embodiment 1 is mounted on a head of an observer viewed
from above (only the image display device is illustrated and the illustration of the
20 frame is omitted) is illustrated in FIG 8.
[0062]
An image display device 100, 200, 300, 400, or 500 of Embodiment 1 or
anyone of Embodiments 2 to 8 to be described later includes:
(A) an image generating device 111 or 211, and
25 (B) a light guide unit 120, 320, or 520 on which light from the image
generating device 111 or 211 is incident, through which the light is guided, and from
which the light is output toward a pupil 21 of an observer 20.
[0063]
In addition, the image generating device 111 or 211 of Embodiment 1 is an
30 image generating device that outputs light to the light guide unit 120, 320, or 520.
[0064]
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Here, an HMD includes:
(a) an eyeglass type frame 10 mounted on a head of the observer 20, and
(b) the image display device 100, 200, 300, 400, or 500. The number of
image display devices may be one (monocular type) or two (binocular type). In the
5 embodiment, there is a binocular type in which two image display devices are
provided. The image display device 100, 200, 300, 400, or 500 may be fixedly
attachable to or detachable from the frame. The image generating device III or 211
displays a single-color (for example, green) image. In addition, the light guide units
120, 320, and 520 are a semi-transmissive type (see-through type). Specifically, at
10 least a portion (more specifically, a light guide plate 121 or 321 and a second
deflecting unit 140 or 340 to be described later) of the light guide unit facing both
pupils (eyes) 21 ofthe observer 20 is semi-transmissive (see-through).
[0065]
Here, in Embodiment 1 or anyone of Embodiments 2 to 8 to be described
15 later, a point at which light (central incident light beam CL) output from the center of
the image generating device III or 211, passing through the nodal point ofthe image
generating device of the parallel light outputting optical system 112 or 254, and
incident on the light guide unit 120, 320, or 520 is incident on the light guide unit
120,320, or 520 is set as a point 0 (light-guide-unit center point 0). A normal line
20 that passes through the light-guide-unit center point 0 in a portion of the light guide
unit 120, 320, or 520 is set as an X axis, and an axial line ofthe light guide unit 120,
320, or 520 that passes through the light-guide-unit center point 0 in a portion of the
light guide unit 120, 320, or 520 is set as a Y axis. The center point of the first
deflecting unit 130 or 330 to be described later is the light-guide-unit center point O.
25 In addition, an optical axis of light incident at the point 0 (light-guide-unit center
point 0) of the light guide unit 120 or 320 among light beams output from the center
of the image generating device III or 211 is set as a l; axis. Here, a relationship
between an (X, Y, Z) orthogonal coordinate system and a (l;, 11, ~) orthogonal
coordinate system when the (l;, 11, ~) orthogonal coordinate system is assumed
30 becomes a relationship in which the 11 axis is consistent with the y axis, and the ~
axis is consistent with the z axis when an (x, y, z) orthogonal coordinate system is
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assumed in a state in which the X axis is caused to be consistent with the C;; axis
according to rotational movement. In Embodiments 1 to 4 and Embodiments 6 to 8,
the C;; axis is consistent with the X axis, the T] axis is consistent with the Y axis, and
the ~ axis is consistent with the Z axis.
5 [0066]
In Embodiment 1 or anyone of Embodiments 2 to 5 and Embodiments 7
and 8 to be described later, the light guide unit 120 or 320 includes:
(B-1) a light guide plate 121 or 321 from which incident light is output after
the incident light propagates through an inside according to total reflection,
10 (B-2) a first deflecting unit 130 or 330, which deflects light incident on the
light guide plate 121 or 321 so that the light incident on the light guide plate 121 or
321 is totally reflected inside the light guide plate 121 or 321, and
(B-3) a second deflecting unit 140 or 340, which deflects light propagating
through the inside of the light guide plate 121 or 321 according to the total reflection
15 a plurality of times so that the light propagating through the inside of the light guide
plate 121 or 321 according to the total reflection is output from the light guide plate
121 or 321.
[0067]
In Embodiment 1, the first deflecting unit 130 and the second deflecting unit
20 140 are disposed inside the light guide plate 121. The first deflecting unit 130
reflects light incident on the light guide plate 121, and the second deflecting unit 140
transmits and reflects light propagating through the inside ofthe light guide plate 121
according to total reflection a plurality of times. That is, the first deflecting unit
130 functions as a reflecting mirror, and the second deflecting unit 140 functions as a
25 semi-transmissive mirror. More specifically, the first deflecting unit 130 provided
inside the light guide plate 121 includes a light reflecting film (a type of mirror)
formed of aluminum (AI), which reflects light incident on the light guide plate 121.
On the other hand, the second deflecting unit 140 provided inside the light guide
plate 121 is formed by a multilayer laminated structure in which a plurality of
30 dielectric laminated films are laminated. The dielectric laminated film is formed by,
for example, a Ti02 film as a high-dielectric-constant material and a Si02 film as a
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low-dielectric-constant material. A multi-layer laminated structure in which a
plurality of dielectric laminated films are laminated is disclosed in Japanese
Unexamined Patent Application Publication (Translation of peT Application) 2005521099.
Although a six-layer dielectric laminated film is illustrated in the drawing,
5 the present disclosure is not limited thereto. A thin section formed of the same
material as the material constituting the light guide plate 121 is sandwiched between
dielectric laminated films. In the first deflecting unit 130, the parallel light incident
on the light guide plate 121 is reflected (or diffracted) so that the parallel light
incident on the light guide plate 121 is totally reflected inside the light guide plate
10 121. On the other hand, in the second deflecting unit 140, the parallel light
propagating through the inside of the light guide plate 121 according to total
reflection is reflected (or diffracted) a plurality of times, and output toward the pupil
21 ofthe observer 20 in a state of parallel light from the light guide plate 121.
[0068]
15 For the first deflecting unit 130, it is only necessary that a slant surface on
which the first deflecting unit 130 is to be formed on the light guide plate 121 be
provided by cutting out a portion 124 on which the first deflecting unit 130 of the
light guide plate 121 is provided, and the cut-out portion 124 of the light guide plate
121 be adhered to the first deflecting unit 130 after a light reflecting film is vacuum
20 evaporated on the slant surface. In addition, for the second deflecting unit 140, it is
only necessary that a multilayer laminated structure in which a plurality of
membranes of the same material (e.g., glass) as the material constituting the light
guide plate 121 and a plurality of dielectric laminated films (for example, formable
by vacuum evaporation) are laminated be manufactured, a slant surface be formed by
25 cutting out a portion 125 on which the second deflecting unit 140 of the light guide
plate 121 is provided, the multilayer laminated structure be adhered to the slant
surface, and the external form be arranged by polishing or the like. Thereby, the
light guide unit 120 having the first deflecting unit 130 and the second deflecting unit
140 provided inside the light guide plate 121 can be obtained.
30 [0069]
Here, in Embodiment 1 or anyone of Embodiments 2 to 5 and
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Embodiments 7 and 8 to be described later, the light guide plate 121 or 321 formed
of an optical glass material or a plastic material has two parallel surfaces (a first
surface 122 or 322 and a second surface 123 or 323) extending in parallel to the light
propagating direction (Y direction) according to internal total reflection of the light
5 guide plate 121 or 321. The first surface 122 or 322 and the second surface 123 or
323 face each other. Parallel light is incident from the first surface 122 or 322
corresponding to a light incidence surface, and the incident parallel light propagates
through the inside according to total reflection and then is output from the first
surface 122 or 322 corresponding to a light output surface. However, the present
10 disclosure is not limited thereto, and the light incidence surface may be formed by
the second surface 123 or 323, and the light output surface may be formed by the
first surface 122 or 322.
[0070]
In Embodiment 1 or 3 to be described later, the image generating device 111
15 is the first form of image generating device, which has a plurality of light emitting
units (light output units, pixels, or virtual pixels) arranged in a 2D matrix.
Specifically, the image generating device 111 includes a reflective spatial light
modulating device 150 and a light source 154 formed by LEDs that emits white light.
Each entire image generating device 111 is fitted inside a housing 113 (denoted by a
20 dashed-dotted line in FIG. 1), and an opening portion (not illustrated) is provided in
the housing 113, and light is output from the parallel light outputting optical system
(collimating optical system 112) through the opening portion. The reflective spatial
light modulating device 150 is formed by an LCD device (LCD) 151 formed by an
LCOS as a light valve and a polarization beam splitter 152 that reflects part of the
25 light output from the light source 154 to guide the reflected light to the LCD device
151 and passes part of light reflected by the LCD device 151 to guide the passed
light to the collimating optical system 112. The liquid crystal display device 151
includes a plurality (for example, 640x480) of pixels (liquid crystal cells) arranged in
a 2D matrix. The polarization beam splitter 152 has a well-known configuration
30 and structure. Unpolarized light output from the light source 154 collides with the
polarization beam splitter 152. The polarization beam splitter 152 passes and
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outputs a P-polarized component outside the system. On the other hand, an Spolarized
component is reflected by the polarization beam splitter 152, incident on
the LCD device 151, reflected inside the LCD device 151, and output from the LCD
device 151. Here, a large number of P-polarized components are included in light
5 output from pixels used for displaying "white" in the light output from the LCD
device 151, and a large number of S-polarized components are included in light
output from pixels used for displaying "black." Accordingly, the P-polarized
component within the light that is output from the LCD device 151 and collides with
the polarization beam splitter 152 passes through the polarization beam splitter 152
10 and is guided to the collimating optical system 112. On the other hand, the Spolarized
component is reflected by the polarization beam splitter 152 and returned
to the light source 154. The collimating optical system 112, for example, includes a
convex lens. To generate parallel light, the light output unit of the image generating
device 111 (more specifically, the LCD device 151) is disposed at a place (position)
15 of a focal distance of the collimating optical system 112. In the case of a color
display, one pixel includes a red light emitting sub-pixel for outputting red light, a
green light emitting sub-pixel for outputting green light, and a blue light emitting
sub-pixel for outputting blue light.
[0071]
20 The frame lOis formed by a front portion 11 arranged on the front side of
the observer 20, two temple portions 13 pivotably mounted on both ends of the front
portion 11 via hinges 12, and ear bend portions (also referred to as tip cells or ear
pads) 14 mounted on tip end portions of the temple portions 13. In addition, nose
pads 10' are mounted thereon. That is, the assembly of the frame 10 and the nose
25 pads 10' has basically substantially the same structure as ordinary glasses. Further,
each housing 113 is mounted on the temple portion 13 using a mounting member 19.
The frame lOis manufactured using metal or plastic. Each housing 113 may be
attachable to or detachable from the temple portion 13 using the mounting member
19. Further, when the observer owns and wears glasses, each housing 113 may be
30 attachable to or detachable from the temple portion of the frame of the glasses owned
by the observer using the mounting member 19.
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[0072]
Further, wirings (signal lines, power lines, and the like) 15 extending from
the image generating devices lIlA and lllB extend from the tip end portion of the
ear bend end portion 14 toward the outside via the temple portion 13 and the inside
5 of the ear bend portion 14, and are connected to the control device (the control circuit
or the control unit) 18. For example, an external image signal is wirelessly
transmitted to the control device 18 or an image signal (image data) is stored in the
control device 18. The control device 18 performs an image display process for an
image signal. The control device 18 can include a well-known circuit. In addition,
10 each of the image generating devices 111A and 111B has a headphone unit 16, and a
headphone wiring 16' extending from each ofthe image generating devices lIlA and
111B extends from the tip end portion of the ear bend portion 14 to the headphone
unit 16 via the temple portion 13 and the inside of the ear bend portion 14. More
specifically, the headphone wiring 16' extends from the tip end portion of the ear
15 bend portion 14 so as to wrap around the rear side of the auricle (auditory capsule)
and extends to the headphone unit 16. According to such a configuration, the image
display device can be neatly formed without giving an impression that the headphone
unit 16 and the headphone wiring 16' are cluttered.
[0073]
20 In addition, an imaging device 17 having a solid-state imaging device
formed by a CCD or CMOS sensor and a lens (these are not illustrated) are mounted
on a center portion 11' ofthe front portion 11 using an appropriate mounting member
(not illustrated), if necessary. A signal output from the imaging device 17 is
transmitted to the image generating device lIlA via a wiring (not illustrated)
25 extending from the imaging device 17.
[0074]
Incidentally, an optical axis of light (central incident light beams CL)
incident at the point 0 (light-guide-unit center point 0) of the light guide unit 120 or
320 among light beams output from the center of the image generating device 111 or
30 211 is set as the Saxis, and a virtual plane including the Saxis and the Yaxis is set as
the sY plane. Because the s axis is consistent with the X axis, the 11 axis is
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consistent with the Y axis, and the ~ axis is consistent with the Z axis as described
above with reference to Embodiments 1 to 4 and Embodiments 6 to 8, the XY plane,
the XZ plane, and YZ plane are consistent with the l;TJ plane, the l;~ plane, and the TJ~
plane, respectively, and the l;Y plane is consistent with the XY plane. Then, light
5 output from the image generating device 111 or 211 and incident at a point (0, V\, Zl)
of the light guide unit 120,320, or 520 forms an angle ez with the l;Y plane (the XY
plane in Embodiments 1 to 4 and Embodiments 6 to 8) and forms an angle ey with
the XZ plane. When ZI';t:O, ez:;t:ey is satisfied. When an incidence angle (XY
plane incidence angle) for the XY plane ofthe light guide unit 120,320, or 520 is ezo,
10 the light (central incident light beams CL) output from the image generating device
111 or 211 and incident at a point (0, 0, 0) ofthe light guide unit 120, 320, or 520 has
ezo=o degrees (see FIG 4C). In addition, ey=o is set.
[0075]
In Embodiment 1, a value of ey is constant regardless of a value of YI, and
15 an absolute value ofez is increased when an absolute value of Zl is increased. The
absolute value of ez may be increased monotonically or stepwise when the absolute
value of Zl is increased. It is only necessary to optimize the value of ez or a shift
amount to be described later by performing various tests or simulations based on
specifications and designations of the image display device, the image generating
20 device, and the light guide unit.
[0076]
Specifically, in Embodiment 1, a microlens array 60 in which a plurality of
microlenses 61 are arranged in a 2D matrix is disposed in the image generating
device 111. Light output from each light emitting unit (light output unit) is output
25 from the image generating device 111 through a microlens 61 facing the light
emitting unit. Alternatively, the image generating device 111 is provided with a
light output angle control member, and light is output from the image generating
device 111 to the light guide unit 120, 320, or 520 through the light output angle
control member. The image generating device 111 has light emitting units arranged
30 in a 2D matrix, the light output angle control member is specifically formed by the
microlens array 60 in which the plurality of microlenses 61 are arranged in a 2D
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matrix, and light output from each light emitting unit is output from the image
generating device 111 through the microlens 61 facing the light emitting unit.
[0077]
The microlens 61, for example, is formed by a cylindrical lens or an
5 anamorphic lens. Here, the axial line (cylindrical axis) of the microlens 61 extends
in parallel to a direction of the image generating device 111 or 211 corresponding to
the Y direction of the light guide unit 120 or 320, a cross-sectional shape when the
microlens 61 is cut in the virtual plane of the image generating device corresponding
to the XZ plane of the light guide unit partially has a curve such as a semicircle, are,
10 or ellipse, and a cross-sectional shape when the microlens 61 is cut in the virtual
plane of the image generating device corresponding to the YZ plane of the light
guide unit is mainly a rectangle.
[0078]
Here, light output from the polarization beam splitter 152 corresponds to
15 light output from each light emitting unit (light output unit), a light output point of
the polarization beam splitter 152 corresponds to a virtual pixel 153, and each virtual
pixel 153 corresponds to a light emitting unit. Hereinafter, the light emitting unit is
denoted by reference numeral 153. A propagation state of light when viewed from
the XZ plane among light beams output from a light emitting unit 153E positioned in
20 an upper portion ofthe image generating device 111 (specifically, an upper portion of
the polarization beam splitter 152) of Embodiment 1 and passing through an opposite
microlens 61E is schematically illustrated in FIG 2A. A propagation state of light
when viewed from the XY plane is schematically illustrated in FIG 2B. Further, a
propagation state of light when viewed from the XZ plane among light beams output
25 from a light emitting unit 153c positioned in a center portion of the image generating
device 111 (specifically, a center portion of the polarization beam splitter 152) of
Embodiment 1 and passing through an opposite microlens 61c is schematically
illustrated in FIG 3A. A propagation state of light when viewed from the XY plane
is schematically illustrated in FIG 3B. In FIGS. 2A and 2B and FIGS. 3A and 3B,
30 the light emitting units 153c and 153E are surrounded by the solid lines.
[0079]
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Here, shift amounts of an optical axis (a normal line passing through the
center of the light emitting unit 153) AX) of the light emitting unit 153 and an optical
axis (a normal line passing through the center of the microlens 61) AX2 of the
microlens 61 facing the light emitting unit 153 are defined based on a value of (0, V),
5 Z). In the example illustrated in FIG. 3A, because of light output from the light
emitting unit 153c positioned in the center portion of the image generating device
111 of Embodiment 1, the value is (0, YI, 0) and the shift amounts of the optical axis
AX) of the light emitting unit 153 and the optical axis AX2 of the microlens 61
facing the light emitting unit 153 are "0." On the other hand, in the example
10 illustrated in FIG 2A, because of light output from the light emitting unit 153E
positioned in the upper portion of the image generating device 111 of Embodiment 1,
the shift amounts ofthe optical axis AX) ofthe light emitting unit 153 and the optical
axis AX2 ofthe microlens 61 facing the light emitting unit 153 are maximum. Light
output from each light emitting unit 153 of the image generating device 111 is
15 schematically illustrated in FIG 4B. In FIG 4B, a circle represents the light
emitting unit 153, and an arrow or black dot drawn in the light emitting unit 153
schematically indicates a direction in which light output from the light emitting unit
153 and passing through the light output angle control member (microlens array) 60
is directed.
20 [0080]
In addition, a radiation angle (divergence angle) co) of light output from the
microlens 61 can be configured to be less than a radiation angle (divergence angle)
COo of light output from the light emitting unit 153 (see FIGS. 2A and 3A). Thereby,
the utilization efficiency of light output from the image generating device 111 can be
25 further improved. The radiation angle (divergence angle) is a radiation angle
(divergence angle) when light flux is projected on the XZ plane.
[0081]
A propagation state of light, which is output from the image generating
device 111 of Embodiment 1 and guided through the light guide unit 120, and
30 reaches the pupil 21, within a plane corresponding to an inside of the XZ plane and
the XY plane is schematically illustrated in FIG. 4A. Incidentally, as described
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above, because an absolute value of 8z is increased when an absolute value of Z\ is
increased in Embodiment 1, all light fluxes (indicated by fine dotted lines R3 in FIG
4A) output from the image generating device 111 and guided through the light guide
unit 120 via the light output angle control member (microlens array) 60 and the
5 parallel light outputting optical system (collimating optical system 112) can be
caused to reach the pupil 21. Therefore, the utilization efficiency of light output
from the image generating device 111 can be improved and power consumption in
the image generating device 111 can be reduced. When the light output angle
control member (microlens array) 60 is not provided in FIG 4A, light flux output
10 from the light emitting unit 153 and reaching the pupil 21 is indicated by a coarse
dotted line R3'. problem that part of the light flux does not reach the pupil 21, a
type of vignetting occurs, and the utilization efficiency of light output from the
image generating device 111 is low leads to an increase in power consumption in the
image generating device 111.
15 [Embodiment 2]
[0082]
Embodiment 2 is a modification of Embodiment 1. The image display
device of Embodiment 2 includes the second form of image generating device/first
form of light guide unit. In an image display device 200 or 400 of Embodiment 2
20 or Embodiment 4 to be described later as illustrated in conceptual diagrams of FIGS.
9 and 11, an image generating device 211 includes a light source 251 and a scanning
unit 253, which scans parallel light output from the light source 251. More
specifically, the image generating device 211 includes:
the light source 251,
25 a collimating optical system 252, which collimates light output from the
light source 251 into parallel light,
the scanning unit 253, which scans the parallel light output from the
collimating optical system 252, and
a parallel light outputting optical system (relay optical system) 254, which
30 relays and outputs the parallel light scanned by the scanning unit 253. The entire
image generating device 211 is fitted inside a housing 213 (indicated by a dashedSP345165XXOO
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dotted line in FIGS. 9 and 11), an opening portion (not illustrated) is arranged in the
housing 213, and light is output from the relay optical system 254 via the opening
portion. Each housing 213 is mounted on a temple portion 13 in an
attachable/detachable state or a fixed state using a mounting member 19.
5 [0083]
The light source 251 includes a light emitting device that emits white light.
The light output from the light source 251 is incident on the collimating optical
system 252 having positive optical power as a whole and output as parallel light.
Alternatively, the light source includes a red light emitting element, which emits red
10 light, a green light emitting element, which emits green light, and a blue light
emitting element, which emits blue light, and each light emitting element is formed
by a semiconductor laser element. Because light of three primary colors output
from the light source passes through a cross prism, color synthesis is performed, an
optical path is integrated, and the light is incident on the collimating optical system
15 252 having positive optical power as a whole and output as parallel light. The
parallel light is reflected by a total-reflection mirror 256, a micromirror is configured
to be rotatable in a 20 direction, horizontal scanning and vertical scanning are
performed by the scanning unit 253 formed by the MEMS capable of twodimensionally
scanning the incident parallel light, one type of 20 image is formed,
20 and a light emitting unit (light output unit) including virtual pixels (the number of the
pixels, for example, can be the same as in Embodiment 1) is generated. Then, light
output from the light emitting unit (virtual pixels) passes through the parallel light
outputting optical system including a well-known relay optical system 254, and the
light flux formed as the parallel light is incident on the light guide unit 120.
25 [0084]
The light output angle control member (microlens array) 60 described in
Embodiment 1 is disposed between the scanning unit 253 and the parallel light
outputting optical system (relay optical system) 254.
[0085]
30 Because the light guide unit 120 on which the light flux formed as the
parallel light by the relay optical system 254 is incident, through which the incident
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light flux is guided, and from which the guided light flux is output has the same
configuration and structure as described in Embodiment 1, detailed description
thereof is omitted. In addition, because the image display device and the HMD of
Embodiment 2 have the same configurations and structures as the image display
5 device and the HMD of Embodiment 1 except for the differences described above,
detailed description thereof is omitted.
[Embodiment 3]
[0086]
Embodiment 3 is also a modification of the image display device of
10 Embodiment 1. The image display device of Embodiment 3 includes the first form
of image generating device/second form of light guide unit. The conceptual
diagram of an image display device 300 of Embodiment 3 is illustrated in FIG lOA.
In addition, a schematic cross-sectional view in which part of a reflective-type
volume hologram diffraction grating is enlarged is illustrated in FIG lOB. In
15 Embodiment 3, as in Embodiment 1, an image generating device 111 includes the
first form of image generating device. The basic configuration and structure of a
light guide unit 320 are the same as those of the light guide unit 120 of Embodiment
1, except for differences in the configurations and the structures of first and second
deflecting units.
20 [0087]
In Embodiment 3, the first deflecting unit and the second deflecting unit are
disposed on a surface of a light guide plate 321 (specifically, a second surface 323 of
the light guide plate 321). The first deflecting unit diffracts light incident on the
light guide plate 321, and the second deflecting unit diffracts light propagating
25 through the inside of the light guide plate 321 according to total reflection a plurality
of times. Here, the first deflecting unit and the second deflecting unit are formed by
diffraction grating elements, specifically, reflective diffraction grating elements, and
more specifically, reflective volume hologram diffraction gratings. In the following
description, the first deflecting unit formed by the reflective volume hologram
30 diffraction grating is referred to as a "first diffraction grating member 330" for
convenience, and the second deflecting unit formed by the reflective volume
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hologram diffraction grating is referred to as a "second diffraction grating member
340" for convenience.
[0088]
In Embodiment 3 or Embodiment 4 to be described later, the first diffraction
5 grating member 330 and the second diffraction grating member 340 include one
diffraction grating layer. In each diffraction grating layer formed by a
photopolymer material, interference fringes corresponding to one type of wavelength
band (or wavelength) are formed, and manufactured using a method of the related art.
The pitch of the interference fringes formed in the diffraction grating layer
10 (diffractive optical element) is constant, and the interference fringes have a linear
shape and extend in parallel to the Z axis. The axial lines of the first diffraction
grating member 330 and the second diffraction grating member 340 are parallel to
the Y axis, and the normal lines thereof are parallel to the X axis.
[0089]
15 To cope with the diffraction and the reflection ofP types (for example, P=3,
and three types of red, green and blue) of light having P different types of
wavelength bands (or wavelengths), the first diffraction grating member 330 and the
second diffraction grating member 340 can be formed by laminating the P diffraction
grating layers formed by the reflective volume hologram diffraction gratings.
20 Interference fringes corresponding to one type of wavelength band (or the
wavelength) are formed on each diffraction grating layer formed by the
photopolymer material, and manufactured using a method of the related art. More
specifically, the first diffraction grating member 330 and the second diffraction
grating member 340 have a structure in which a diffraction grating layer that diffracts
25 and reflects red light, a diffraction grating layer that diffracts and reflects green light,
and a diffraction grating layer that diffracts and reflects blue light are laminated.
The pitch of the interference fringes formed in the diffraction grating layer
(diffraction grating element) is constant, and the interference fringes have a linear
shape and extend in parallel to the Z direction. In FIGS. lOA and 11, the first
30 diffraction grating member 330 and the second diffraction grating member 340 are
illustrated in one layer. By adopting such a configuration, an increase in the
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diffraction efficiency, an increase in the diffraction acceptance angle, and the
optimization of the diffraction angle when light having each wavelength band (or the
wavelength) is diffracted and reflected in the fIrst diffraction grating member 330
and the second diffraction grating member 340 can be achieved.
5 [0090]
A schematic partial cross-sectional view in which the reflective volume
hologram diffraction grating is enlarged is illustrated in FIG lOB. In the reflective
volume hologram diffraction grating, interference fringes having a slant angle ~ are
formed. Here, the slant angle ~ represents an angle formed by the surface of the
10 reflective volume hologram diffraction grating and the interference fringes. The
interference fringes are formed from the inside of the reflective volume hologram
diffraction grating to the surface thereof. The interference fringes satisfy a Bragg
condition. Here, the Bragg condition is a condition that satisfIes the following
Expression (A). In Expression (A), m represents a positive integer, "A represents a
15 wavelength, d represents the pitch of the grating surface (a gap of virtual planes
including the interference fringes in the direction of the normal line), and 0
represents a complementary angle of an angle at which light is incident on the
interference fringes. In addition, when light penetrates into the diffraction grating
member at an incidence angle \If, the relationship among the complementary angle 0,
20 the slant angle ~, and the incidence angle \If is shown in Expression (B).
[0091]
m·"A=2·d·sin(0) (A)
0=900-(~+\If) (B)
[0092]
25 As described above, the first diffraction grating member 330 is arranged on
(adhered to) the second surface 323 of the light guide plate 321 and diffracts and
reflects parallel light incident on the light guide plate 321 so that the parallel light
incident from the first surface 322 to the light guide plate 321 is totally reflected
inside the light guide plate 321. Further, as described above, the second diffraction
30 grating member 340 is arranged on (adhered to) the second surface 323 of the light
guide plate 321 and diffracts and reflects the parallel light propagating through the
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inside of the light guide plate 321 according to total reflection a plurality of times,
and the parallel light is directly output from the first surface 322 of the light guide
plate 321. However, the present disclosure is not limited thereto. The light-guideplate
incidence surface may be configured by the second surface 323, and the light-
5 guide-plate output surface may be configured by the first surface 322.
[0093]
Then, the parallel light propagates through the inside of the light guide plate
321 according to total reflection and then is output therefrom. Alternatively,
parallel light of three colors of red, green, and blue propagates through the inside
10 according to total reflection and then is output therefrom. At this time, because the
light guide plate 321 is thin, and a path of light that propagates through the inside of
the light guide plate 321 is long, the number oftotal reflections until the parallel light
reaches the second diffraction grating member 340 differs according to a view angle
(horizontal view angle). In further detail, the number of reflections of parallel light
15 incident at an angle (horizontal view angle) in a direction close to the second
diffraction grating member 340 among parallel light beams incident on the light
guide plate 321 is less than that of parallel light incident on the light guide plate 321
at an angle in a direction away from the second diffraction grating member 340.
This is because parallel light incident on the light guide plate 321 at an angle close to
20 the second diffraction grating member 340 among parallel light beams diffracted and
reflected in the first diffraction grating member 330 has a larger angle formed with
the normal line of the light guide plate 321 when light propagating through the inside
of the light guide plate 321 collides with the inner surface ofthe light guide plate 321
than parallel light incident on the light guide plate 321 at an angle in a direction
25 reverse thereto. In addition, the shape of the interference fringes formed inside the
second diffraction grating member 340 and the shape of the interference fringes
formed inside the first diffraction grating member 330 are symmetrical with respect
to the XZ plane of the light guide plate 321.
[0094]
30 A light guide plate 321 in accordance with Embodiment 4 to be described
later also basically has the same configuration and structure as the light guide plate
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321 described above. The image display device and the HMD of Embodiment 3
has the same configuration and structure as the image display devices and the HMDs
of Embodiments 1 and 2 except for the differences described above, and thus
detailed description thereof is omitted.
5 [Embodiment 4]
[0095]
Embodiment 4 is a modification of the image display device in accordance
with Embodiment 3. Specifically, the image display device of Embodiment 4
includes the second form of image generating apparatus/second form of light guide
10 unit. A conceptual diagram of the image display device of Embodiment 4 is
illustrated in FIG 11. A light source 251, a collimating optical system 252, a
scanning unit 253, a parallel light outputting optical system (relay optical system
254), and the like in the image display device 400 of Embodiment 4 have the same
configurations and structures (the second form of image generating device) as those
15 of Embodiment 2. In addition, a light guide unit 320 in accordance with
Embodiment 4 has the same configuration and structure as those of the light guide
unit 320 in accordance with Embodiment 3. Because the image display device and
the HMD of Embodiment 4 substantially have the same configuration and structure
as the image display devices and the HMDs of Embodiments 1 and 2 except for the
20 differences described above, detailed description thereof is omitted.
[Embodiment 5]
[0096]
Embodiment 5 is a modification of the image display devices in accordance
with Embodiments 1 to 4. In addition, a schematic diagram of the image display
25 device of Embodiment 5 viewed from the side is illustrated in FIG 12.
[0097]
In Embodiments 1 to 4, in the image display device 100 or 300, the central
incident light beam CL output from the center of the image generating device 111 or
211 and passing through the nodal point of the parallel light outputting optical
30 system 112 or 254 is designed to be incident at an incidence angle (XY plane
incidence angle) ezo of 0 degrees for the XY plane ofthe light guide plate 121 or 321.
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That is, Szo=O degrees.
[0098]
That is, in such an image display device represented by the image display
device 100, as illustrated in FIG. 29B, the central incident light beam CL output from
5 the center of the image generating device IlIon the optical axis of the collimating
optical system 112 is converted into approximately parallel light by the collimating
optical system 112 and then incident on the first surface (incidence surface) 122 of
the light guide plate 121. The parallel light propagates in a propagation direction A
while being totally reflected between the first surface 122 and the second surface 123
10 by the first diffraction unit 130. Subsequently, the central incident light beam CL is
reflected and diffracted by the second deflecting unit 140 and output from the first
surface 122 of the light guide plate 121 within the XY plane, and reaches the pupil
21 ofthe observer 20.
[0099]
15 In a see-through type image display device, it is preferable to shift the light
guide unit 120, 320, or 520 to be arranged below the line of sight of the observer in
the horizontal direction (the horizontal-direction line of sight of the observer) so that
the light guide unit 120, 320, or 520 does not interfere with viewing when the
observer 20 views an observation target located in the horizontal direction. In such
20 a case, the entire image display device 100 or 300 is arranged below the horizontaldirection
line of sight of the observer. In such a configuration, as illustrated in FIG
30, which illustrates a form of image display device of the related art, it is necessary
to incline the entire image display device 100 by an angle Szo", and the angle Szo" by
which the image display device 100 can be inclined may be limited, or the degree of
25 freedom in design may decrease from the relationship with the mounting portion
(temple portion) of the eyeglass type frame to be mounted on the head of the
observer. Therefore, it is more preferable to form the arrangement of a high degree
of freedom and an image display device having a high degree of freedom in design
without interfering with the horizontal-direction line of sight ofthe observer.
30 [0100]
In Embodiment 5, the central incident light beam CL is formed to intersect
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the XY plane at an angle (ezo;t:O) other than zero degrees (see FIG. 4D and FIG. 12).
The central incident light beam CL is included within the XZ plane. In addition, in
Embodiment 5, the angle ezo at which the central incident light beam CL intersects
the XY plane is an elevation angle. That is, the central incident light beam CL is
5 directed from the lower side of the XY plane to the XY plane, and collides with the
XY plane. The XY plane intersects the vertical surface at an angle other than zero
degrees, specifically, at an angle ezo.
[0101]
In Embodiment 5, the angle ezo=5 degrees. That is, the light guide unit
10 120, 320, or 520 is inclined by the angle ezo with respect to the vertical surface. In
other words, the light guide unit 120,320, or 520 is inclined by an angle of (90-ezo)
degrees with respect to the horizontal surface. In addition, the central incident light
beam CL output from the light guide unit 120, 320, or 520 is inclined by an angle
2ezo with respect to the horizontal surface. That is, when the observer 20 views a
15 target located at an infinite distance in the horizontal direction, the central incident
light beam CL output from the light guide unit 120, 320, or 520 and incident on the
pupil 21 of the observer 20 forms a depression angle ezo' (=2ezo). The angle
formed by the central incident light beam CL and the normal line of the light guide
unit 120,320, or 520 is ezo.
20 [0102]
In the image display device of Embodiment 5, the central incident light
beam CL intersects the XY plane at an angle (ezo) other than zero degrees. Here,
the central incident light beam CL output from the light guide unit 120 or 320 and
incident on the pupil 21 of the observer 20 forms a depression angle ezo ', but there is
25 a relationship ofezo'=2ezo. On the other hand, in the example illustrated in FIG. 30,
in order to obtain the same depression angle, it is necessary to incline the entire
image display device by an angle ezo". Here, the relationship between ezo" and ezo
is ezo"=2ezo, and hence the light guide unit should be inclined by 2ezo with respect
to the vertical surface in the example illustrated in FIG. 30. On the other hand, in
30 Embodiment 5, it is only necessary to incline the light guide unit by ezo with respect
to the vertical surface, and to horizontally hold the image generating device.
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Accordingly, a mounting angle of the image display device at the time of mounting
the image display device on a mounting portion of the eyeglass type frame is less
limited and a high degree of freedom in the design can be obtained. In addition,
because the inclination of the light guide unit with respect to the vertical surface is
5 less than that of the example illustrated in FIG 30, a phenomenon that external light
is reflected by the light guide unit and incident on the pupil 21 of the observer 20
does not easily occur. Therefore, an image having higher quality can be displayed.
[0103]
Because the image display device of Embodiment 5 has the same
10 configuration and structure as the image display devices of Embodiments 1 to 4
except for the differences described above, detailed description thereof is omitted.
[Embodiment 6]
[0104]
Embodiment 6 is also a modification of the image display devices in
15 Embodiments 1 to 4. A schematic diagram of an image display device of
Embodiment 6 viewed from the front is illustrated in FIG 13, and a schematic
diagram thereof viewed from above is illustrated in FIG 14.
[0105]
In Embodiment 6, a light guide unit 520 includes a semi-transmissive mirror
20 on which light output from the image generating devices 111A and 111B is incident
and from which the light is output toward the pupil 21 of the observer 20. In
addition, although a structure in which the light output from the image generating
devices lIlA and 111B propagates through the inside of a transparent member 521
such as a glass plate or a plastic plate and is incident on the light guide unit 520
25 (semi-transmissive mirror) is provided in Embodiment 6, a structure in which the
light propagates through the air and is incident on the light guide unit 520 may be
provided. In addition, the image generating device may be configured as the image
generating device 211 described in Embodiment 2.
[0106]
30 Each of the image generating devices lIlA and IIIB is mounted on a front
portion 11, for example, using a screw. In addition, the member 521 is mounted on
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each of the image generating devices IlIA and ll1B, and the light guide unit 520
(semi-transmissive mirror) is mounted on the member 521. Because the image
display device of Embodiment 6 has substantially the same configuration and
structure as the image display devices of Embodiments 1 to 4 except for the
5 differences described above, detailed description thereof is omitted.
[Embodiment 7]
[0107]
Embodiment 7 relates to an HMD in which the image display device of the
present disclosure, specifically, anyone of the image display devices 100, 200, 300,
10 400, and 500 described in Embodiments 1 to 6, is embedded. A schematic diagram
of the HMD of Embodiment 7 viewed from the front is illustrated in FIG 15. A
schematic diagram of the HMD of Embodiment 7 (in a state in which a frame is
assumed to be removed) viewed from the front is illustrated in FIG 16. In addition,
a schematic diagram of the HMD of Embodiment 7 viewed from above is illustrated
15 in FIG 17. In addition, although the image display device represented by the image
display device 100 will be described, needless to say, the image display devices 200,
300, 400, and 500 can be applied.
[0108]
The HMD of Embodiment 7 includes:
20 (A) an eyeglass type frame 10 mounted on a head of an observer 20, and
(B) two image display devices 100. The HMD in accordance with
Embodiment 7 or 8 to be described later is also a binocular type in which two image
display devices 100 are provided.
[0109]
25 In addition, the HMD of Embodiment 7 further includes a connecting
member 70, which connects the two image display devices 100. The connecting
member 70 is mounted on a side facing the observer (that is, between the observer 20
and the frame 10) in a center portion 11' of a front portion 11 of the frame 10
(corresponding to a portion of a bridge in an ordinary pair of eyeglasses) located
30 between two pupils 21 of the observer 20 using screws (not illustrated). In addition,
nose pads 10' are mounted on a side facing the observer 20 in the connecting
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member 70. In FIGS. 17 and 20, the illustration of the nose pads 10' is omitted.
The frame 10 and the connecting member 70 are formed ofa metal or plastic, and the
shape of the connecting member 70 is a curved rod shape.
[0110]
5 Further, the projected image ofthe connecting member 70 is included within
the projected image of the frame 10. That is, when the HMD is viewed from the
front side of the observer 20, the connecting member 70 is hidden behind the frame
10, so that the connecting member 70 is not visible. In addition, although the two
image display devices 100 are connected by the connecting member 70, the image
10 generating devices lIlA and 111B can be specifically accommodated in the housing
113 and mounted on both end portions of the connecting member 70, respectively, so
that the mounting state is adjustable. Each of the image generating devices lIlA
and ll1B is located outside the pupil 21 of the observer 20. Specifically, a=O.1xL,
f3=0.5xL, and y=0.9xL, where a is the distance between a mounting-portion center
15 ll1Ae of the image generating device lIlA on one side and one end portion (one
end piece) lOA of the frame 10, f3 is the distance from a center 70e of the connecting
member 70 to the one end portion (one end piece) lOA of the frame, y is the distance
between a mounting-portion center 111Be of the image generating device 111B on
the other side and the one end portion (one end piece) lOA of the frame, and L is the
20 length ofthe frame.
[0111 ]
For the mounting of the image generating devices (specifically, the image
generating devices lIlA and ll1B) on the end portions of the connecting member 70,
specifically, the connecting member 70 is provided with through-holes (not
25 illustrated) at three positions in each end portion thereof, and the image generating
devices lIlA and 111B are provided with tapped holes (screw-engagement portions
(not illustrated)) corresponding to the through-holes. Screws (not illustrated) pass
through the through-holes, and are screw engaged with the holes formed in the image
generating devices 111A and 111 B. A spring is inserted between the screw and the
30 hole. Thus, the mounting state of each image generating device (the inclination of
each image generating device relative to the connecting member) can be adjusted
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according to the fastening states of the screws. After the mounting, the screws are
hidden by a cover (not illustrated). In FIGS. 16 and 19, connecting members 70
and 80 are hatched with diagonal lines so that the connecting members 70 and 80 are
clearly shown.
5 [0112]
As described above, in the HMD of Embodiment 7, the connecting member
70 connects the two image display devices 100. The connecting member 70 is
mounted on the center portion 11' of the frame 10 located between the two pupils 21
of the observer 20. That is, a structure in which the image display devices 100 are
10 directly mounted on the frame lOis not adopted here. Accordingly, a displacement
(positional change) of the image generating device 111A or 111B is not caused by
deformation of the frame 10 even when the temple portions 13 are expanded to the
outside when the frame lOis mounted on the head of the observer 20 and hence the
frame lOis deformed, or such displacement, if any, is very small. Therefore, it is
15 possible to reliably prevent angles of convergence of left and right images from
being changed. Moreover, because it is unnecessary to enhance the rigidity of the
front portion 11 of the frame 10, it is possible to avoid causing an increase in the
weight of the frame 10, a decrease in design quality, or an increase in cost. In
addition, because the image display devices 100 are not directly mounted on the
20 eyeglass type frame 10, the design, color and the like of the frame 10 can be freely
selected according to the observer's preference. Thus, there are few restrictions
imposed on the design of the frame 10, so that the degree of freedom in design is
high. In addition, the connecting member 70 is hidden behind the frame 10 when
the HMD is viewed from the front side of the observer. Accordingly, high design
25 quality can be given to the HMD.
[Embodiment 8]
[0113]
Embodiment 8 is a modification of Embodiment 7. A schematic diagram
of an HMD of Embodiment 8 viewed from the front is illustrated in FIG 18. A
30 schematic diagram of the HMD of Embodiment 8 (in a state in which a frame is
assumed to be removed) viewed from the front is illustrated in FIG 19. In addition,
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a schematic diagram of the HMD of Embodiment 8 viewed from above is illustrated
in FIG 20.
[0114]
In the HMD of Embodiment 8, a rod-shaped connecting member 80 is
5 different from Embodiment 7, and connects two light guide units 120 instead of
connecting the two image generating devices lilA and IIIB. The two light guide
units 120 are manufactured in an integrated manner, and the connecting member 80
can be formed to be mounted on the light guide unit 120 manufactured in the
integrated manner.
10 [0115]
Here, even in the HMD of Embodiment 8, the connecting member 80 is
mounted on the center portion 11' of the frame 10 located between the two pupils 21
of the observer 20, for example, using screws, and each image generating device 111
is located outside the pupil 21 of the observer 20. Each image generating device
15 111 is mounted on the end portion of the light guide unit 120. When a distance
from a center 80c of the connecting member 80 to one end portion of the frame 10 is
set as (3 and a length of the frame lOis set as L, (3=0.5xL is satisfied. Even in
Embodiment 8, values of a' and y' are the same as values of a and y of Embodiment
7.
20 [0116]
The frame 10 and each image display device of Embodiment 8 have the
same configurations and structures as the frame 10 and the image display device of
Embodiment 7, and therefore detailed description thereof is omitted. In addition,
because the HMD of Embodiment 8 also has substantially the same configuration
25 and structure as the HMD of Embodiment 7 except for the differences described
above, detailed description thereof is omitted.
[0117]
Although the present disclosure has been described based on the preferred
embodiments, the present disclosure is not limited to these embodiments. The
30 configurations and structures of the image display device and the image generating
device described in the embodiments are merely exemplary, and can be changed
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appropriately. Although a Y direction is set as a direction generally horizontal to
the observer in Embodiment 1, the Y direction may be set as a direction generally
perpendicular to the observer depending upon arrangement states of the image
display device, the image generating device, and the light guide unit. In addition,
5 an angle 8y may be an angle other than zero degrees. In this case, light incident at a
point (0, YI, Zl) of the light guide unit penetrates the light guide unit in a direction
reverse to a light guide direction of light in the light guide unit. That is, the light
incident at a point (0, YI, Zl) of the light guide unit forms an acute angle as a whole
with the light guide direction of light in the light guide unit. Further, in other words,
10 it is preferable that an angle formed by a projected image for the XY plane of the
light incident at the point (0, Y1,ZI) of the light guide unit and the Y axis be an acute
angle.
[0118]
In addition, for example, a surface relief-type hologram (see U.S. Patent No.
15 20040062505 AI) may be arranged on the light guiding plate. In addition, in the
light guide unit of Embodiment 3 or 4, the first deflecting unit formed by a
transmissive hologram can be configured to be disposed on the first surface 332 of
the light guide plate 321, and the second deflecting unit formed by a reflective
hologram can be configured to be disposed on the second surface 323. In such a
20 configuration, light incident on the first deflecting unit is diffracted, satisfies a total
reflection condition within the light guide plate, and propagates to the second
deflecting unit. In the second deflecting unit, light is diffracted, reflected, and
output from the light guide plate. In the light guide unit of Embodiment 3 or 4, the
diffraction grating element can be formed by a transmissive diffraction grating
25 element. Alternatively, anyone of the first and second deflecting unit can be
formed by a reflective diffraction grating element and the other can be formed by the
transmissive diffraction grating element. Alternatively, the diffraction grating
element can be a reflective blazed grating element or a surface relief hologram.
Although a binocular type in which two image display devices are provided has been
30 described in the embodiment, a monocular type in which one image display device is
provided may be provided.
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[0119]
As a modification of an image generating device suitably for use in
Embodiments 1 and 3, for example, as illustrated in a conceptual view of FIG. 21, an
active matrix type of image generating device can include a light emitting panel in
5 which light emitting elements 501 formed by semiconductor light emitting elements
are arranged in a 20 matrix, and display an image by controlling a light
emitting/non-light-emitting state of each light emitting element 501 so that the light
emitting state of the light emitting element 501 is directly visible. Light output
from the image generating device is incident on a light guide plate 121 or 321 via a
10 light output angle control member (microlens array) 60 and a collimating optical
system 112.
[0120]
Alternatively, as illustrated in a conceptual diagram of FIG. 22, a colordisplay
image generating device can include:
15 (a) a red light emitting panel 511R in which red light emitting elements
501R for emitting red light are arranged in a 2D matrix;
(f3) a green light emitting panel 511G in which green light emitting elements
501G for emitting green light are arranged in a 20 matrix;
(y) a blue light emitting panel 511B in which blue light emitting elements
20 501B for emitting blue light are arranged in a 20 matrix; and
(8) a unit (e.g., a dichroic prism 503) for integrating light output from the
red, green, and blue light emitting panels 511 R, 511 G, and 511B into one optical path.
Light emitting/non-light-emitting states of the red, green, and blue light emitting
elements 501R, 501G, and 501B are controlled independently. Light output from
25 this image generating device is also incident on the light guide plate 121 or 321 via
the light output angle control member (microlens array) 60 and the collimating
optical system 112. Reference numeral 512 denotes microlenses for condensing
light output from the light emitting elements.
[0121]
30 Alternatively, a conceptual view of an image generating device including
light emitting panels 511R, 511G, and 511B in which light emitting elements 501R,
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5010, and 501B are arranged in a 20 matrix is illustrated in FIG 23. Light output
from the light emitting panels 511R, 5110, and 511B is incident on a dichroic prism
503 after passage/non-passage thereof is controlled by light passage control devices
504R, 5040, and 504B. The optical paths of the light beams are integrated into one
5 optical path, and the light beams are incident on the light guide plate 121 or 321 via
the light output angle control member (microlens array) 60 and the collimating
optical system 112.
[0122]
Alternatively, a conceptual view of an image generating device including
10 light emitting panels 511R, 5110, and 511B and the like in which light emitting
elements 501R, 5010, and 501B are arranged in a 20 matrix is illustrated in FIG 24.
Light output from the light emitting panels 511 R, 511 0, and 511B is incident on a
dichroic prism 503 and optical paths thereof are integrated into one optical path.
Passage/non-passage of the light output from the dichroic prism 503 is controlled by
15 a light passage control device 504, and the light is incident on the light guide plate
121 or 321 via the light output angle control member (microlens array) 60 and the
collimating optical system 112.
[0123]
Alternatively, as illustrated in FIG 25, an image generating device can
20 include a light emitting element 501R for emitting red light, a light passage control
device (e.g., an LCD device 504R), which is a type of light valve for controlling
passage/non-passage of the red light output from the light emitting element 501R, a
light emitting element 501G for emitting green light, a light passage control device
(e.g., an LCD device 504G), which is a type of light valve for controlling
25 passage/non-passage of the green light output from the light emitting element 5010,
a light emitting element 501B for emitting blue light, a light passage control device
(e.g., an LCD device 504B), which is a type of light valve for controlling
passage/non-passage of the blue light output from the light emitting element 501B,
light guide members 502 for guiding the light output from the light emitting elements
30 501R, 5010, and 501B formed by GaN semiconductors, and a unit (e.g., a dichroic
prism 503) for integrating the optical paths of the light into one optical path. The
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light output from the dichroic prism 503 is incident on the light guide plate 121 or
321 via the light output angle control member (microlens array) 60 and the
collimating optical system 112.
[0124]
5 Additionally, the present technology may also be configured as below.
(l) An image display device including:
(A) an image generating device; and
(B) a light guide unit on which light from the image generating device is
incident, through which the light is guided, and from which the light is output toward
10 a pupil of an observer,
wherein when a point at which light output from a center of the image
generating device is incident on the light guide unit is set as a point 0, a normal line
passing through the point 0 in a portion of the light guide unit is set as an X axis, an
axis of the light guide unit passing through the point 0 in a portion of the light guide
15 unit is set as a Y axis, an optical axis of light incident at the point 0 of the light guide
unit among light beams output from a center of the image generating device is set as
a Saxis, and a virtual plane including the ~ axis and the Y axis is set as a sY plane,
light output from the image generating device and incident at a point (0, V), ZI)
forms an angle 8z with the sY plane and forms an angle 8y with an XZ plane, and
20 wherein when ZI';t:O, 8z:;t:8y is satisfied.
(2) The image display device according to (l),
wherein a value of8y is constant regardless ofa value ofY), and
wherein an absolute value of8z is increased when an absolute value of ZI is
increased.
25 (3) The image display device according to (2),
wherein the absolute value of 8z can be increased monotonically or stepwise
when the absolute value of ZI is increased.
(4) The image display device according to (2) or (3),
wherein the image generating device has a light emitting unit arranged in a
30 two-dimensional (2D) matrix,
wherein a microlens array in which a plurality of microlenses are arranged
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in a 2D matrix is disposed in the image generating device,
wherein light output from each light emitting unit is output from the image
generating device through a microlens facing the light emitting unit, and
wherein shift amounts of an optical axis of the light emitting unit and an
5 optical axis of the microlens facing the light emitting unit are defined based on a
value of (0, VI, ZI).
(5) The image display device according to (4),
wherein the microlens is formed by a cylindrical lens or an anamorphic lens.
(6) The image display device according to (4) or (5),
10 wherein a radiation angle of light output from the microlens is less than a
radiation angle of light output from the light emitting unit.
(7) The image display device according to anyone of(1) to (3),
wherein an image generating device has a light output angle control member,
and
15 wherein light is output from the image generating device to a light guide
unit through the light output angle control member.
(8) The image display device according to (7),
wherein the image generating device has light emitting units arranged in a
2D matrix,
20 wherein the light output angle control member is formed by a microlens
array in which a plurality of microlenses are arranged in a 2D matrix, and
wherein light output from each light emitting unit is output from the image
generating device through a microlens facing the light emitting unit.
(9) The image display device according to (8),
25 wherein shift amounts of an optical axis of the light emitting unit and an
optical axis of the microlens facing the light emitting unit are defined based on a
value of(O, VI, ZI).
(10) The image display device according to (8) or (9),
wherein the microlens is formed by a cylindrical lens or an anamorphic lens.
30 (11) The image display device according to anyone of (8) to (10),
wherein a radiation angle of light output from the microlens is less than a
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radiation angle of light output from the light emitting unit.
(12) The image display device according to anyone of (1) to (11),
wherein the light guide unit includes
(B-1) a light guide plate from which the incident light is output after the
5 incident light propagates through an inside according to total reflection,
(B-2) a first deflecting unit configured to deflect the light incident on the
light guide plate so that the light incident on the light guide plate is totally reflected
inside the light guide plate, and
(B-3) a second deflecting unit configured to deflect the light propagating
10 through the inside of the light guide plate according to the total reflection a plurality
of times so that the light propagating through the inside of the light guide plate
according to the total reflection is output from the light guide plate.
(13) The image display device according to anyone of(1) to (12),
wherein the image generating device is formed by a liquid crystal display
15 device, an organic electro luminescence display device, or a light emitting element
array.
(14) An image generating device for outputting light to a light guide unit including a
light guide plate from which incident light is output after the incident light
propagates through an inside according to total reflection, a first deflecting unit
20 configured to deflect light incident on the light guide plate so that the light incident
on the light guide plate is totally reflected inside the light guide plate, and a second
deflecting unit configured to deflect light propagating through the inside of the light
guide plate according to the total reflection a plurality of times so that the light
propagating through the inside of the light guide plate according to the total
25 reflection is output from the light guide plate,
wherein, when a point at which light output from a center of the image
generating device is incident on the light guide unit is set as a point 0, a normal line
passing through the point 0 in a portion of the light guide unit is set as an X axis, an
axis of the light guide unit passing through the point 0 in a portion of the light guide
30 unit is set as a Y axis, an optical axis of light incident at the point 0 ofthe light guide
unit among light beams output from a center of the image generating device is set as
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a Saxis, and a virtual plane including the ~ axis and the Y axis is set as a sY plane,
light output from the image generating device and incident at a point (0, Y\, ll)
forms an angle 8z with the sY plane and forms an angle 8y with an Xl plane, and
wherein when ll';t:O, 8z:;t:8y is satisfied.
5 [0125]
It should be appreciated from the foregoing that some embodiments of the
invention provide an image display device, comprising: a plurality of light emitting
units, arranged in an array comprising a plurality of rows extending in a first
direction, each of the plurality of light emitting units having an optical axis; and a
10 plurality of microlenses, arranged in an array so that light emitted from each of the
plurality of light emitting units passes through a corresponding one of the plurality of
microlenses, each of the plurality of microlenses having an optical axis; wherein the
optical axis of light emitting units in at least one of the plurality of rows is offset
from the optical axis of the corresponding microlenses in the at least one of the
15 plurality of rows.
[0126]
The plurality of rows of light emitting units may comprise at least one first
row, and an offset between the optical axis of a light emitting unit in a particular row
and the optical axis of a corresponding microlens may vary as function of a distance
20 between the particular row and the at least one first row. For example, an offset
between the optical axis of a light emitting unit in the particular row and the optical
axis of a corresponding microlens increases as the distance between the particular
row and the at least one first row increases. The at least one first row may, for
example, reside substantially in a center ofthe plurality of rows.
25 [0127]
The plurality of rows of light emitting units may comprise rows below the at
least one first row in the array, and the optical axes of light emitting units in the rows
below the at least one first row may reside at an offset above the optical axis of
corresponding microlenses. The plurality of rows of light emitting units may
30 comprise rows above the at least one first row in the array, and the optical axes of
light emitting units in the rows above the at least one first row may reside at an offset
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below the optical axis of corresponding microlenses.
[0128]
The plurality of rows of light emitting units may comprise a first row, a
second row adjacent the first row in the array, and a third row adjacent the second
5 row in the array, and a first distance between an optical axis of light emitting units in
the first row and an optical axis of light emitting units in the second row is greater
than a second distance between an optical axis of light emitting units in the second
row and an optical axis of light emitting units in the third row. The first row may,
for example, reside substantially in a center of the plurality of rows. In some
10 embodiments, the second row may reside above the first row in the array, and the
third row may reside above the second row in the array. In other embodiments, the
second row may reside below the first row in the array, and the third row may reside
below the second row in the array.
[0129]
15 The plurality of rows may comprise at least one edge row farthest away
from the at least one first row in the array, and the at least one ofthe plurality ofrows
in which the optical axis of light emitting units is different than the optical axis of the
corresponding microlenses may comprise the at least one edge row. In some
embodiments, the at least one edge row may comprise a row below the at least one
20 first row in the array, and the optical axis of light emitting units in the at least one
edge row may reside above the optical axis of the corresponding microlenses. In
other embodiments, the at least one edge row may comprise a row above the at least
one first row in the array, and the optical axis of light emitting units in the at least
one edge row may reside below the optical axis ofthe corresponding microlenses.
25 [0130]
In some embodiments, the array in which the plurality of light emitting units
are arranged may comprise a plurality of columns.
[0131]
Some embodiments of the invention provide a head-mounted display,
30 comprising: an eyeglass type frame configured for mounting on a head; and an image
display device, affixed to the eyeglass type frame. The head-mounted display may
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comprise an optical waveguide configured to propagate light from the light emitting
unit along the first direction. In some embodiments, the image display device may be
affixed to the eyeglass type frame so that, when the eyeglass type frame is mounted
on a head, the first direction in which the plurality of rows extends is substantially
5 horizontal. In other embodiments, the image display device may be affixed to the
eyeglass type frame so that, when the eyeglass type frame is mounted on a head, the
first direction in which the plurality of rows extends is substantially vertical.
[0132]
Some embodiments of the invention provide a head-mounted display,
10 comprising: an optical system; an optical waveguide; a first diffraction grating and a
second diffraction grating, each residing on a portion of the optical waveguide;
a frame, configured for mounting on a head; and an image display device, affixed to
the frame.
[0133]
15 Some embodiments of the invention provide an image display device,
comprising: a plurality of light emitting units, arranged in an array comprising a
plurality of rows, the plurality of rows comprising at least one first row; and a
plurality of microlenses, arranged in an array so that light emitted from each of the
plurality of light emitting units passes through a corresponding one of the plurality of
20 microlenses, each of the plurality of microlenses having an optical axis; wherein light
from a light emitting unit in a particular row passes through a corresponding
microlens at an angle to the optical axis, and the angle varies as a function of a
distance between the particular row and the at least one first row.
[0134]
25 It should be understood by those skilled in the art that various modifications,
combinations, sub-combinations and alterations may occur depending on design
requirements and other factors insofar as they are within the scope of the appended
claims or the equivalents thereof.
[0135]
30 The present disclosure contains subject matter related to that disclosed in
Japanese Priority Patent Application JP 2012-057452 filed in the Japan Patent Office
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on March 14,2012, the entire content of which is hereby incorporated by reference.

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What is claimed is:
1. An image display device, comprising:
a plurality of light emitting units, arranged in an array comprising a plurality
of rows extending in a first direction, each of the plurality of light emitting units
5 having an optical axis; and
a plurality of microlenses, arranged in an array so that light emitted from each
of the plurality of light emitting units passes through a corresponding one of the
plurality of microlenses, each ofthe plurality of microlenses having an optical axis;
wherein the optical axis of light emitting units in at least one of the plurality
10 of rows is offset from the optical axis of the corresponding microlenses in the at least
one ofthe plurality of rows.
2. The image display device of claim 1, wherein the plurality of rows of light
emitting units comprises at least one first row, and an offset between the optical axis
15 of a light emitting unit in a particular row and the optical axis of a corresponding
microlens varies as function of a distance between the particular row and the at least
one first row.
3. The image display device of claim 2, wherein an offset between the optical
20 aXIS of a light emitting unit in the particular row and the optical axis of a
corresponding microlens increases as the distance between the particular row and the
at least one first row increases.
4. The image display device of claim 3, wherein the plurality of rows of light
25 emitting units comprises rows below the at least one first row in the array, and the
optical axes of light emitting units in the rows below the at least one first row reside
at an offset above the optical axis ofcorresponding microlenses.
5. The image display device of claim 3, wherein the plurality of rows of light
30 emitting units comprises rows above the at least one first row in the array, and the
optical axes of light emitting units in the rows above the at least one first row reside
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at an offset below the optical axis of corresponding microlenses.
6. The image display device of claim 2, wherein the at least one first row
resides substantially in a center ofthe plurality ofrows.
5
7. The image display device of claim 1, wherein the plurality of rows of light
emitting units comprises a first row, a second row adjacent the first row in the array,
and a third row adjacent the second row in the array, and a first distance between an
optical axis of light emitting units in the first row and an optical axis of light emitting
10 units in the second row is greater than a second distance between an optical axis of
light emitting units in the second row and an optical axis of light emitting units in the
third row.
8. The image display device of claim 7, wherein the first row resides
15 substantially in a center of the plurality of rows.
9. The image display device of claim 7, wherein the second row resides above
the first row in the array, and the third row resides above the second row in the array.
20 10. The image display device of claim 7, wherein the second row resides below
the first row in the array, and the third row resides below the second row in the array.
11. The image display device of claim 1, wherein the plurality of rows
comprises at least one edge row farthest away from the at least one first row in the
25 array, and the at least one of the plurality of rows in which the optical axis of light
emitting units is different than the optical axis of the corresponding microlenses
comprises the at least one edge row.
12. The image display device of claim 11, wherein the at least one edge row
30 comprises a row below the at least one first row in the array, and wherein the optical
axis of light emitting units in the at least one edge row resides above the optical axis
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ofthe corresponding microlenses.
13. The image display device of claim 11, wherein the at least one edge row
comprises a row above the at least one first row in the array, and wherein the optical
5 axis of light emitting units in the at least one edge row resides below the optical axis
ofthe corresponding microlenses.
14. The image display device of claim 1, wherein the array in which the
plurality of light emitting units are arranged comprises a plurality of columns.
10
15. A head-mounted display, comprising:
an eyeglass type frame configured for mounting on a head; and
the image display device ofclaim 1, affixed to the eyeglass type frame.
15 16. The head-mounted display of claim 15, further comprising an optical
waveguide configured to propagate light from the light emitting unit along the first
direction.
20 17. The head-mounted display of claim 15, wherein the image display device is
affixed to the eyeglass type frame so that, when the eyeglass type frame is mounted
on a head, the first direction in which the plurality of rows extends is substantially
horizontal.
25 18. The head-mounted display of claim 15, wherein the image display device is
affixed to the eyeglass type frame so that, when the eyeglass type frame is mounted
on a head, the first direction in which the plurality of rows extends is substantially
vertical.
30 19. A head-mounted display, comprising:
an optical system;
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an optical waveguide;
~t a first diffraction grating and a second diffraction grating, each residing on a
portion ofthe optical waveguide;
a frame, configured for mounting on a head; and
5 the image display device of claim 1, affixed to the frame.
20. An image display device, comprising:
a plurality of light emitting units, arranged in an array comprising a plurality
of rows, the plurality of rows comprising at least one first row; and
10 a plurality of microlenses, arranged in an array so that light emitted from each
of the plurality of light emitting units passes through a corresponding one of the
plurality of microlenses, each ofthe plurality of microlenses having an optical axis;
wherein light from a light emitting unit in a particular row passes through a
corresponding microlens at an angle to the optical axis, and the angle varies as a
15 function of a distance between the particular row and the at least one first row.