FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
& The Patent Rules, 2003
COMPLETE SPECIFICATION
1. TITLE OF THE INVENTION:
DISPLAYAND DISPLAY OBSERVATION METHOD
2. APPLICANT:
Name: TOPPAN PRINTING CO., LTD.
Nationality: Japan
Address: 5-1, Taito 1-chome, Taito-ku, Tokyo 1100016 Japan
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in
which it is to be performed:
2
DESCRIPTION
TECHNICAL FIELD
[0001] The present invention relates to a display body
that displays a plurality of pieces of information and a
method for observing the display body.
BACKGROUND ART
[0002] Objects such as securities, certificates, brandname
products, high-price products, electronic devices, and
identifications should be counterfeit-resistant to protect
their values and information from others. To this end, a
counterfeit-resistant display body or display section may be
attached to or integrated into such objects.
[0003] An example of an object including a counterfeitresistant
display section is a banknote having a paper carrier
and motifs printed on the surface of the carrier. A plurality
of minute holes extends through the carrier. In reflected
light observation of this banknote, the image information
formed by the motifs on the banknote is visible, while the
image information formed by the minute holes is invisible. In
transmitted light observation, however, the image information
formed by the minute holes is visible (see Patent Document 1,
for example).
PRIOR ART DOCUMENT
Patent Document
[0004] Patent Document 1: Japanese Laid-Open Patent
Publication No. 2000-501036
SUMMARY OF THE INVENTION
Problems that the Invention is to Solve
3
[0005] The motifs of the banknote are two-dimensional
print on the surface of the carrier, while the minute holes
are three-dimensional structures extending through the entire
thickness of the carrier. Two-dimensional print like the
motifs and three-dimensional structures like the minute holes
are formed on or in the carrier in different steps. Typically,
the motifs and the holes are positioned relative to the
carrier at different times with different methods due to their
differences in the dimensions and the techniques of processing.
This may result in the positions of motifs relative to the
holes shifted from the predetermined positions or varied among
banknotes.
[0006] Such a problem is not limited to a display body
that limits counterfeiting of an object and may occur in a
display body for decorating an object and a display body that
is observed for its own quality.
[0007] It is an objective of the present invention to
provide a display body that displays a plurality of pieces of
information in accurate positional relationship, and a method
for observing the display body.
Means for Solving the Problems
[0008] To achieve the foregoing objective and in
accordance with one aspect of the present invention, a display
body is provided that includes a first surface, a second
surface, a first optical component, and a second optical
component. The first surface includes a first optical surface
and a second optical surface. First light is incident on the
first surface from an observation side. The second surface is
located opposite to the observation side with respect to the
first surface. Second light is incident on the second surface
from a side opposite to the observation side with respect to
the second surface. The first optical component includes the
first optical surface. The first optical component forms
first information, which is displayed on the observation side,
4
from the first light received on the first optical surface.
The second optical component includes the second optical
surface. The second optical component receives the second
light transmitted through the second surface, forms second
information, which is displayed on the observation side, from
the second light, and emits the second information from the
second optical surface. The second optical component is an
uneven structure. The uneven structure includesan uneven
structure portion including a dielectric that transmits light,
anda metal layer covering at least a part of the uneven
structure portion. A surface of the metal layer that is
opposite to an interface between the uneven structure portion
and the metal layer is the second optical surface. The uneven
structure includes a plasmon structure that receives the
second light on the interface and excites surface plasmons on
the metal layer so that the second optical surface emits
transmitted light that forms the second information and
differs from the second light in color.
[0009] To achieve the foregoing objective and in
accordance with another aspect of the present invention, a
method for observing a display body is provided. The display
body includes a first surface, a second surface, a first
optical component, and a second optical component. The first
surface includes a first optical surface and a second optical
surface. First light is incident on the first surface from an
observation side. The second surface is located opposite to
the observation side with respect to the first surface.
Second light is incident on the second surface from a side
opposite to the observation side with respect to the second
surface. The first optical component includes the first
optical surface. The first optical component forms first
information, which is displayed on the observation side, from
the first light received on the first optical surface. The
second optical component includes the second optical surface.
The second optical component receives the second light
5
transmitted through the second surface, forms second
information, which is displayed on the observation side, from
the second light, and emits the second information from the
second optical surface. The second optical component is an
uneven structure. The uneven structure includesan uneven
structure portion including a dielectric that transmits light,
anda metal layer covering at least a part of the uneven
structure portion. A surface of the metal layer that is
opposite to an interface between the uneven structure portion
and the metal layer is the second optical surface. The uneven
structure includes a plasmon structure that receives the
second light on the interface and excites surface plasmons on
the metal layer so that the second optical surface emits
transmitted light that forms the second information and
differs from the second light in color. The method
includes:causing the first light to be incident on the first
surface;observing the first information formed by the first
optical component from the first light incident on the first
surface; causing the second light to be incident on the second
surface; andobserving the second information formed by the
second optical component from the second light incident on the
second surface.
[0010] Since both of the first optical component and the
second optical component include parts of the first surface as
optical surfaces, the first optical component and the second
optical component may be positioned relative to each other by
a common method. Alternatively, the first optical component
and the second optical component may be formed using the same
type of technique.
[0011] For example, the shape ofan original plate
including a die for shaping the first optical component and a
die for shaping the second optical component may be
transferred to a substrate, or a substrate may be etched using
a single mask that includes a mask for forming the first
optical component and a mask for forming the second optical
6
component.
[0012] Alternatively, the shape of an original plate for
forming the first optical component may be transferred to a
substrate, and then the shape of an original plate for forming
the second optical component may be transferred to the
substrate, or a substrate may be etched using a mask for
forming the first optical component and then etched using a
mask for forming the second optical component.
[0013] Such a method increases the accuracy of the
position of the second optical component relative to the first
optical component and thus the accuracy of the display
position of the second information relative to the display
position of the first information.
Effect of the Invention
[0014] The present invention sets a plurality of pieces
of informationin accurate positional relationship.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Fig. 1 is a perspective view showing the
perspective structure of a display body according to one
embodiment of the present invention.
Fig. 2 is a partial enlarged view of a region 2 in Fig.
1, which is a part of the display body.
Fig. 3 is an enlarged cross-sectional view showing a
part of the cross-sectional structure of a third component.
Fig. 4 is a partial perspective view showing a part of
the structure of the third component.
Fig. 5 is a partial perspective view showing a part of
the perspective structure of an example of a first component.
Fig. 6 is a partial perspective view showing a part of
the perspective structure of an example of a first component.
Fig. 7 is a partial perspective view showing a part of
the perspective structure of an example of a first component.
Fig. 8 is a partial perspective view showing a part of
7
the perspective structure of an example of a first component.
Fig. 9 is a partial perspective view showing a part of
the perspective structure of an example of a first component.
Fig. 10 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body.
Fig. 11 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body.
Fig. 12 is a diagram for illustrating the observation
method and operation of the display body.
Fig. 13 is a diagram for illustrating the observation
method and operation of the display body.
Fig. 14 is a diagram for illustrating the observation
method and operation of the display body.
Fig. 15 is a perspective view showing the perspective
structure of a display body of a modification.
Fig. 16 is a perspective view showing the perspective
structure of a display body of a modification.
Fig. 17 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 18 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 19 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 20 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 21 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 22 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
8
Fig. 23 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 24 is a partial cross-sectional view showing a part
of the cross-sectional structure of a display body of a
modification.
Fig. 25 is a plan view showing the planar structure of a
verification subject of a modification.
Fig. 26 is a perspective view showing the perspective
structure of a display body of a modification.
Fig. 27 is a diagram for illustrating the operation of
the display body of the modification.
Fig. 28 is a diagram for illustrating the operation of
the display body of the modification.
MODES FOR CARRYING OUT THE INVENTION
[0016] Referring to Figs. 1 to 14, one embodiment of a
display body and a method for observing the display body
according to the present invention is now described. In the
following descriptions, the overall structure of the display
body, the structure of the optical components of the display
body, the structures of the front surface of the display body,
and the method for observing the display body are described in
this order.
[0017] [Overall Structure of Display Body]
Referring to Figs. 1 and 2, the overall structure of a
display body is now described. Fig. 2 is an enlarged view of
a part of the display body shown in Fig. 1.
[0018] As shown in Fig. 1, a display body 10 has the
shape of a rectangular plate and includes a front surface 10a,
which is an example of the first surface. The front surface
10a of the display body 10 is a surface on which first light
is incident. The side from which the first light is incident
on the front surface 10a is an observation side. The display
9
body 10 includes a back surface 10b, which is an example of
the second surface located opposite to the observation side
with respect to the front surface 10a. Second light is
incident on the back surface 10b from the side opposite to the
observation side with respect to the back surface 10b.
The display body 10 may have the shape of a circular
plate or a rectangular solid, instead of a rectangular plate.
[0019] The display body 10 includes a plurality of
optical components including first optical components and
second optical components. Each first optical component
includes a part of the front surface 10a that functions as a
first optical surface for providing optical effects. That is,
the first optical component includes the first optical surface.
The first optical component forms first information from the
first light received on the first optical surface. The first
information is displayed on the observation side.
[0020] The display body 10 includes a first component 11
and a second component 12 as examples of first optical
components, but the display body 10 may include only one first
optical component or three or more first optical components.
[0021] The first component 11 includes a plurality of
first display elements 11a defined inside the first component
11. Each first display element 11a is a circular structure in
a plan view. The first display elements 11a are arranged at
predetermined intervals in the first component 11. The second
component 12 includes a plurality of second display elements
12a defined inside the second component 12. Each second
display element 12a is a circular structure in a plan view.
The second display elements 12a are arranged at predetermined
intervals in the second component 12.
[0022] Each of the first and second display elements 11a
and 12a may be a structure having a polygonal shape, such as a
triangular or tetragonal shape, instead of a circular shape.
In addition, display elements may be arranged in contact with
one another in each component.
10
[0023] The first component 11 and the second component 12
form different pieces of information. The first component 11
forms the letter A as first information, and the second
component 12 forms the letter B as first information.
[0024] The first and second components 11 and 12 may form
the same information. The first information is not limited to
a letter, such as the letter A or B, and may be a symbol, a
number, a graphic, such as an illustration or a pattern, and a
combination of two or more letters, symbols, numbers, and
graphics.
[0025] Each second optical component includes a part of
the front surface 10a that functions as a second optical
surface for providing optical effects. That is, the second
optical component includes the second optical surface. The
second optical component receives the second light transmitted
through the back surface 10b, forms second information
displayed on the observation side from the second light, and
emits the second information from the second optical surface.
[0026] The display body 10 includes a third component 13,
which functions as a second optical component and is located
in the front surface 10a independent of the first and second
components 11 and 12. The third component 13 includes a
plurality of third display elements 13a defined inside the
third component 13. Each third display element 13a is a
circular structure in a plan view. The third display elements
13a are arranged at predetermined intervals in the third
component 13.
[0027] The third display element 13a may be a structure
having a polygonal shape, such as a triangular or tetragonal
shape, instead of a circular shape. In addition, third
display elements 13a may be arranged in contact with one
another in the third component 13.
[0028] The third component 13 forms the letter C as
second information. However, the second information is not
limited to a letter, such as the letter C, and may be a symbol,
11
a number, a graphic, such as an illustration and a pattern,
and a combination of two or more letters, symbols, numbers,
and graphics. In addition, the second information formed by
the third component 13 is not limited to a letter, a symbol, a
number, or a graphic and may be color information, such as the
proportion of an area having a certain color in the third
component 13, coloration of the third component 13, or
presence or absence of a color, and positional information,
such as the position of a certain color or the position of a
section of the third component 13 that has a color.
[0029] As shown in Fig. 2, the display body 10 includes a
plurality of fourth components 14, which function as second
optical components. Each fourth component 14 is surrounded by
a first display element 11a. Each fourth component 14
includes a plurality of fourth display elements 14a defined
inside the fourth component 14. Each fourth display element
14a is a circular structure in a plan view. The fourth
display elements 14a are arranged at predetermined intervals
in the fourth component 14.
[0030] Each fourth component 14 forms the letter A as
second information. The information formed by the fourth
component 14 differs from the information formed by the second
component 12 and the information formed by the third component
13. Alternatively, the information formed by the fourth
component 14 may be the same as the information formed by the
second component 12 or the information formed by the third
component 13 but differ from the information formed by the
first component 11.
[0031] In the front surface 10a of the display body 10,
when the area occupied by the first component 11 is S1 and the
area occupied by the fourth component 14 is S2, the
relationship between the areas S1 and S2 satisfies Expression
(1) below.
0.01 S2/S1 0.4 (Expression 1)
[0032] When Expression (1) is satisfied, the size of the
12
fourth component 14 relative to the size of the first
component 11 is small enough so that the fourth component 14
surrounded by the first component 11 is likely to be
indiscernible when reflection light from the front surface 10a
of the display body 10 is observed as the effect of the first
component 11.
[0033] The area S1 is preferably between 0.16 mm2 and 1
mm2, inclusive, for example, and the area S2 is preferably
between 100 μm2 and 90,000 μm2, inclusive. The area S1 is
preferably large enough to be discernibleto the observer with
the naked eye, while the area S2 is preferably small enough to
be indiscernible to the observer with the naked eye.
[0034] The display body 10 may include two or more second
optical components that are independent of the first optical
components in the display body 10, like the third component 13
described above, or may include only one second optical
component surrounded by a first optical component, like the
fourth component 14 described above. The display body 10 may
include only one of a second optical component that is
independent of a first optical component in the display body
10 and a second optical component surrounded by a first
optical component.
[0035] [Structure of Optical Component]
Referring to Figs. 3 to 9, the structures of the optical
components of the display body 10 are now described in detail.
The structure of a second optical component is described
referring to Figs. 3 and 4, and the structures of first
optical component are described referring to Figs. 5 to 9.
For the sake of the convenience of explanation, the metal
layer of the second optical component is omitted in Fig. 4.
[0036] The third component 13 and the fourth components
14, which are second optical components, differ from each
other in the positions in the display body 10 but have the
same structure as optical components. Thus, the structure of
13
the third component 13 is described, and the structure of the
fourth component 14 is not described. In addition, the first
component 11 and the second component 12, which are first
optical components, differ from each other in the positions in
the display body 10 but have the same structure as optical
components. Thus, the structure of the first component 11 is
described, and the structure of the second component 12 is not
described.
[0037] As shown in Fig. 3, the third component 13, which
is an example of the second uneven structure, includes an
uneven structure portion 21 and a metal layer 22 partially
covering the uneven structure portion 21. The uneven
structure portion 21 is made of a light-transmitting
dielectric. The third component 13 includes a plasmon
structure, which includes an interface 23 between the uneven
structure portion 21 and the metal layer 22. The plasmon
structure receives the second light on the interface 23 and
excites surface plasmons on the metal layer 22, thereby
absorbing light of certain wavelengths in the second light and
converts the light into transmitted light that differs from
the second light in color.
[0038] The uneven structure portion 21 includes a plate
portion 31, which has a base surface 31a serving as one
surface, and a plurality of protrusions 32, which projects
from the base surface 31a. The base surface 31a is an example
of the second base surface, and the plate portion 31 is an
example of the second plate portion. The protrusions 32 are
examples of the second protrusions. Each protrusion 32
includes a top surface 32a, which is spaced apart from the
base surface 31a, and two side surfaces 32b connected to the
base surface 31a. The top surfaces 32a are in a single
imaginary plane S, which is substantially parallel with the
base surface 31a. The distance D between the base surface 31a
and the imaginary plane S is preferably between 30 nm and 500
nm, inclusive.
14
[0039] Each protrusion 32 has the shape of a rectangular
prism, but the protrusion 32 may have the shape of other
polygonal prism, such as a triangular prism or a pentagonal
prism, a cylinder, an elliptical prism, a cone, or a pyramid.
When the protrusion 32 has the shape of a polygonal prism,
each corner of the polygonal prism may have a curvature.
Further, each protrusion 32 may include a plurality of steps
in the side surfaces 32b connecting the top surface 32a to the
base surface 31a. When the protrusion 32 has steps in the
side surfaces 32b and is shaped so that the dimensions in the
width direction increase in steps from the top surface 32a to
the base surface 31a, the metal layer 22 may be formed on each
of the surfaces in the side surfaces 32b that are
substantially parallel with the imaginary plane S.
[0040] The metal layer 22 is formed on the top surfaces
32a of the protrusions 32 and the entire section of the base
surface 31a that is free of the protrusions 32. In the third
component 13, the side surfaces 32b of the protrusions 32, the
front surface 22a of the metal layer 22 formed on the base
surface 31a, and the front surface 22a of the metal layer 22
formed on the top surface 32a of eachprotrusion 32 form a part
of the front surface 10a of the display body 10. The front
surface 22a of the metal layer 22 of the third component 13
forms the second optical surface.
[0041] Themetal layer 22 may be formed only on the base
surface 31a or only on the top surfaces 32a. Alternatively,
the metal layer 22 may be formed on a part of the base surface
31a or only on some of the top surfaces 32a.
[0042] For example, the metal layer 22 has a
predetermined thickness M of between 20 nm and 100 nm,
inclusive, preferably between 40 nm and 60 nm, inclusive.
When the thickness M of the metal layer 22 is greater than or
equal to 40 nm, the difference between the transmittance of
the first optical component and the transmittance of the
second optical component will be more noticeable. The
15
thickness M of the metal layer 22 that is less than or equal
to 60 nm allows the metal layer 22 to resist cracks.
[0043] The metal layer 22 preferably includes a material
of which the real part of the complex dielectric constant is
negative over the ultraviolet to visible light range and thus
has a high reflectivity. Suitable materials for the metal
layer 22 include aluminum, gold, silver, and titanium nitride.
Aluminum and silver, which have high reflectivity, are
particularly suitable for the metal layer 22. Of the possible
materials for the metal layer 22, silver has the highest
reflectivity, and aluminum is less expensive. When the
complex dielectric constant of the material forming the metal
layer 22 is as described above, the light transmitted by
excitation of surface plasmons is in the visible light range.
This allows the observer to recognize the second information
emitted by the display body 10.
[0044] The metal layer 22 may be formed by physical vapor
deposition, such as vacuum deposition or sputtering. The
metal layer 22 that is formed by vacuum deposition includes a
minute uneven structure in the front surface 22a of the metal
layer 22. However, sucha minute uneven structure formed by
vacuum deposition is not large enough to affect excitation of
surface plasmons. Thus, the uneven structure formed by vacuum
deposition, or surface roughness, in the metal layer 22 is
acceptable.
[0045] The third component 13 may include a protective
layer, which transmits light and covers the metal layer 22.
The protective layer limits breaking of the minute uneven
structures of the third component 13. In addition, the
protective layer allows at least one of the selection of
wavelengths that cause surface plasmon resonances, or the
selection of wavelength width, and the light absorption amount
to differ from those of a structure that does not include a
protective layer.
[0046] Theprotective layer may be made of a light16
transmitting plastic or a dielectric material. The examples
of plastic that may be used for the protective layer include
polyethylene, polypropylene, polytetrafluoroethylene,
polymethyl methacrylate, and polystyrene.
[0047] The examples of a dielectric material that may be
used for the protective layer include Sb2O3, Fe2O3, TiO2, CdS,
CeO2, ZnS, PbCl2, CdO, WO3, SiO, Si2O3, In2O3, PbO, Ta2O3, ZnO,
ZrO2, MgO, Si2O2, MgF2, CeF3, CaF2, AlF3, Al2O3, and GaO.
[0048] When the protective layer is made of a plastic,
colorants may be added to the plastic. Depending on the
wavelengths the colorant absorbs, the protective layer allows
at least one of the selection of wavelengths that cause
surface plasmon resonances, or the selection of wavelength
width, and the light absorption amount to differ from those of
a structure that does not include a protective layer. In
addition, changing the colorant in the protective layer to
another colorant changes at least one of the selection of
wavelengths that cause surface plasmon resonances, or the
selection of wavelength width, and the light absorption amount,
depending on the difference between the wavelengths absorbed
by the colorants.
[0049] As shown in Fig. 4, the protrusions 32 on the base
surface 31a of the plate portion 31 are arranged at regular
intervals in the X direction, which is one direction, and also
arranged at regular intervals in the Y direction, which is
perpendicular to the X direction. The interval between two
protrusions 32 in the X direction is the same as that in the Y
direction. In other words, the protrusions 32 are arranged in
a square lattice pattern on the base surface 31a. The pitch
P1, which is the interval between twoprotrusions 32 in the X
direction, is preferably between 100 nm and 600 nm, inclusive,
for example.
[0050] The height of the protrusions 32 is preferably
between 50 nm and 600 nm, inclusive. When the height of the
protrusions 32 is greater than or equal to 50 nm, surface
17
plasmons are more likely to absorb certain wavelengths of the
incident light and convert the incident light into transmitted
light that differs from the incident light in color. The
height of the protrusions 32 that is less than or equal to 600
nm facilitates formation of the protrusions32.
[0051] In order for each third display element 13a
forming the third component 13 to emit transmitted light of a
predetermined color, the plasmon structure of the third
display element 13a preferably includes two or more
protrusions 32 and a metal layer 22 that covers at least the
top surface 32a of each protrusion 32.
[0052] Theprotrusions 32 may be arranged in a triangular
lattice pattern or a hexagonal lattice pattern on the base
surface 31a. The protrusions 32 that are arranged in a
triangle or hexagonal lattice pattern differ from the
protrusions 32 that are arranged in a square lattice pattern
in the number of pitches P1. Different arrangements of the
protrusions 32 result in different states of the surface
plasmon excitation on the metal layer 22.
[0053] When the protrusions 32 are arranged in a
hexagonal lattice pattern, a protrusion 32 is spaced apart
from the six protrusions 32 surrounding that protrusion 32 by
the same distance. That is, all of the protrusions 32 are
arranged such that adjacent ones of the protrusions 32 are
located at regular intervals, that is, at the same pitch P1.
The protrusions 32 that are arranged in a hexagonal lattice
pattern are all arranged at regular intervals, resulting in
substantially the same surface plasmon state over the metal
layer 22. This facilitates adjustment of the color of the
light transmitted through each third display element 13a as
compared with a structure in which the protrusions 32 are
arranged in a square lattice pattern.
[0054] Provided that the material of the uneven structure
portion 21 and the pitch P1 of the protrusions 32 remain
unchanged, a change in the fill factor, which is the ratio of
18
the dimension of the protrusions 32 in the X or Y direction to
the pitch P1, changes the color of light emitted by the
plasmon structure.
[0055] The uneven structure portion 21 may be made of
quartz, for example. The uneven structure portion 21 may be
made of other inorganic materials that transmit visible light,
such as titanium oxides or magnesium fluoride, or organic
materials that transmit visible light, such as acrylic resins
including urethane-modified acrylic resin and epoxy-modified
acrylic resin, epoxy resins, and other resins.
[0056] When the uneven structure portion 21, which
includes the plate portion 31 and the protrusions 32, is made
of an inorganic material, the uneven structure portion 21 may
be formed by chemically or physically etching a substrate of
the inorganic material. When the uneven structure portion 21
is made of a resin, the plate portion 31 and the protrusions
32 may be formed by transferring the shape of an original
plate to the resin before hardening.
[0057] Each third display element 13a in the third
component 13 includes the interface 23 between the uneven
structure portion 21 and the metal layer 22. The surface
plasmons excited on the metal layer 22 allow the third display
element 13a to emit light that differs from the irradiated
light in color. All third display elements 13a emit light of
the same color. The third display elements 13a display second
information by emitting the light having a predetermined color
resulting from the surface plasmon excitation. The light of
the predetermined color within the light emitted by the
display body 10 allows the observer of the display body 10 to
recognize the second information.
[0058] Referring to Figs. 5 to 9, five different examples
of the structure of the first component 11 are now described.
The first component 11 shown in Fig. 5 is an example of
the first uneven structure. The first component 11 may
include a plate portion 41, which is shaped like a plate and
19
made of a dielectric, and a metal layer 42 formed on a base
surface 41a, which is one surface of the plate portion 41.
The plate portion 41 is an example of the first plate portion.
The first component 11 is an uneven structure having
unevenness resulting from the step between the plate portion
41 and the metal layer 42. The front surface 42a of the metal
layer 42 and the section of the base surface 41a that is free
of the metal layer 42 form a part of the front surface 10a of
the display body 10.
[0059] In this first component 11, the front surface 42a
of the metal layer 42 functions as a reflection surface, which
is an example of the first optical surface. The first
component 11 forms first information, which is displayed on
the observation side, by reflecting the first light received
on the front surface 42a of the metal layer 42.
[0060] As shown in Fig. 6, the first component 11 may be
an uneven structure including a plate portion 41 and a
plurality of protrusions 43 projecting from the base surface
41a. The plate portion 41 is an example of the first plate
portion, and the base surface 41a is an example of the first
base surface. The protrusions 43 are examples of the first
protrusions. In this first component 11, the plate portion 41
and the protrusions 43 form an uneven structure portion 40.
Each protrusion 43 is shaped like a rectangular prism
extending in the X direction. The protrusions 43 are arranged
at regular intervals in the Y direction at a predetermined
pitch P2. The first component 11 has the shape of a square
wave in cross-section in the Z direction, which is parallel
with the thickness direction of the display body 10. The
first component 11 is a laminar grating.
[0061] In this first component 11, the surface of each
protrusion 43, which is a top surface 43a spaced apart from
the base surface 41a, two side surfaces 43b of each protrusion
43, which are connected to the base surface 41a, and the
section of the base surface 41a that is free of the
20
protrusions 43 form a part of the front surface 10a of the
display body 10. In this first component 11, a plurality of
top surfaces 43a functions as a diffraction surface, which is
an example of the first optical surface, and the first
component 11 forms first information on the observation side
by diffracting the first light received on the top surfaces
43a.
[0062] As shown in Fig. 7, when the first component 11 is
a reflective diffraction grating, the first component 11 may
have a sinusoidal cross-section in the Z direction. That is,
each protrusion 44 extends in the X direction and
substantially has the shape of a triangular prism having
curved side surfaces 44a extending in the X direction. The
protrusions 44 are arranged in the Y direction at a pitch P2.
[0063] In this first component 11, the surfaces of the
protrusions 44 form a part of the front surface 10a of the
display body 10 and function as a diffraction surface, which
is an example of the first optical surface. The surfaces of
the protrusions 44 are side surfaces 44a on opposite sides of
each of the tops 44b, which are located successively in the Y
direction.
[0064] When the first component 11 is a reflective
diffraction grating, the first component 11 may have a
sawtooth-shaped cross-section in the Z direction. That is,
the first component 11 may be a blazed grating. Further, when
the first component 11 is a reflective diffraction grating,
the protrusions of the first component 11 may each have the
shape of a polygonal prism other than the triangular or
rectangular prism described above.
[0065] The first component 11 may include multiple
diffraction gratings having different cross-sectional shapes
in the Z direction. Such diffraction gratings differ from
each other in the intensity of diffraction light, forming
first information using the multiple intensities of
diffraction light beams. The cross-section in the Z direction
21
of the first component 11 may be shaped such that interference
occurs between two light beams diffracted by the first
component 11. Such a first component 11 forms first
information using the interference fringes caused by the light
interference. Further, the first component 11 may include
multiple diffraction gratings having different cross-sectional
shapes in the Z direction and form first information using the
multiple intensities of diffraction light beams and the light
interference.
[0066] When the first component 11 is a reflective
diffraction grating, the pitch P2 is preferably between 200 nm
and 2,000 nm, inclusive, more preferably between 500 nm and
1,000 nm, inclusive. The pitch P2 that is between 500 nm and
1,000 nm, inclusive facilitates diffraction of visible
wavelengths in the first light incident on the first component
11, allowing for easier visual perception of the first
information formed by the first component 11.
[0067] When the first component 11 is a diffraction
grating, the depth of the depressions in the diffraction
grating is preferably between 50 nm and 600 nm, inclusive.
When the depth of the depressions in the diffraction grating
is greater than or equal to 50 nm, the diffraction grating
effectively diffracts light. A depth of 600 nm or less
facilitates formation of the diffraction grating.
[0068] The depth of the depressions in the first
component 11 is substantially equal to the height of the
protrusions 32 in the third component 13, which is the depth
of the depressions formed between the protrusions 32. This
facilitates simultaneous formation of the first and third
components 11 and 13.
[0069] As shown in Fig. 8, the first component 11 may be
an uneven structure including a plate portion 41 and a
plurality of protrusions 45 projecting from the base surface
41a. The protrusions 45 are arranged irregularly on the base
surface 41a. In this first component 11, the plate portion 41
22
and the protrusions 45 form an uneven structure portion 40.
Each protrusion 45 may be semielliptical and has a dimension
in the Z direction that is greater than the dimension in the X
direction. The protrusions 45 have the same shape.
[0070] In this first component 11, the surface of each
protrusion 45 and the section of the base surface 41a that is
free of the protrusions 45 form a part of the front surface
10a of the display body 10. In the first component 11, the
surface of each protrusion 45 and the section of the base
surface 41a that is free of the protrusions 45 function as a
scattering surface, which is an example of the first optical
surface, and the first component 11 forms first information,
which is displayed on the observation side, by scattering the
first light received on the scattering surface.
[0071] When the first optical surface of the first
component 11 is a light scattering surface, the base surface
41a may include a plurality of depressions arranged
irregularly. The depressions may extend from the base surface
41a toward a non-base surface, which is the surface of the
plate portion 41 opposite to the base surface 41a. The nonbase
surface may form a part of the back surface 10b of the
display body 10. Alternatively, the non-base surface may be
adhered to an additional substrate, and the surface of the
additional substrate that is opposite to the non-base surface
may serve as the back surface 10b of the display body 10.
[0072] In addition, the protrusions 45 on the base
surface 41a may differ from one another in shape and the ratio
between the dimension in the Z direction and the dimension in
the X direction. Further, the depressions in the base surface
41a may be identical in shape, or may differ from one another
in the ratio between the dimension in the Z direction and the
dimension in the X direction.
[0073] As shown in Fig. 9, the first component 11 may be
an uneven structure including a plate portion 41 and a
plurality of protrusions 46 projecting from the base surface
23
41a. The plate portion 41 includes a plurality of depressions
47, which extends from the base surface 41a toward a non-base
surface 41b. The non-base surface 41b may be a part of the
back surface 10b of the display body 10. Alternatively, the
non-base surface 41b of the plate portion 41 may be adhered to
an additional substrate, and the surface of the additional
substrate that is opposite to the non-base surface 41b may
serve as the back surface 10b of the display body 10.
[0074] In this first component 11, the plate portion 41,
the protrusions 46, and the depressions 47 form an uneven
structure portion 40. Each protrusion 46 may be
semielliptical and have a dimension in the Z direction that is
greater than the dimension in the X direction. Each
depression 47 is defined by a curved surface.
[0075] Theprotrusions 46 and the depressions 47 of the
first component 11 are arranged alternately in both X and Y
directions. In the first component 11, the distance between
the tops of two protrusions 46 that are adjacent to each other
in the X direction is uniform, and the distance between the
tops is a pitch P3. The protrusions 46 are arranged at
regular intervals in a direction intersecting the X direction,
and the depressions 47 are arranged at regular intervals in
the direction intersecting the X direction.
[0076] In this first component 11, the surface of each
protrusion 46, the curved surface defining each depression 47,
and the section of the base surface 41a that is free of the
protrusions 46 and the depressions 47 form a part of the front
surface 10a of the display body 10. In the first component 11,
the surfaces of the protrusions 46 and the curved surfaces
defining the depressions 47 form the first optical surface.
[0077] When the pitch P3 of the first component 11 is
greater than or equal to the visible light range, the
protrusions 46 arranged at regular intervals and the
depressions 47 arranged at regular intervals diffract the
light incident on the front surface 10a of the display body 10.
24
The first component 11 thus emits diffraction light in
predetermined directions, which differ from the direction of
the normal to the plate portion 41, for example. When the
pitch P3 is less than the visible light range, the first
component 11 absorbs the light incident on the first optical
surface. Such absorption by the first component 11 reduces
the light reflectivity of the first component 11 as compared
with a structure that does not have protrusions or depressions.
[0078] When the first light incident on the first optical
surface enters the uneven structure portion 40 having the
pitch P3 that is less than the visible light range, the
refractive indices for visible light vary continuously over
the first component 11, typically providing impedance matching
at the interface between the uneven structure portion 40 and
the air. This reduces reflections of light. The reflectivity
of the first light is thus reduced.
[0079] In a similar manner as the third component 13, the
first component 11 may include a protective layer covering the
uneven structure portion 40. The protective layer may be made
of a light-transmitting plastic or a dielectric material.
Such a first component 11 provides impedance matching at the
interface between the uneven structure portion 40 and the
protective layer, reducing reflections of light. In addition,
a structure in which the display body 10 is adhered to another
member using an adhesive resin layer covering the first
component 11 still provides impedance matching at the
interface between the uneven structure portion 40 and the
adhesive layer, thereby reducing reflections of light.
[0080] Accordingly, when the first light is incident on
the front surface 10a of the display body 10 and the first
component 11 is viewed in the direction of the normal to the
plate portion 41, the first component 11 displays first
information in black or dark gray on the observation side.
The first component 11 thus forms the first information using
the diffraction light and the absorption of the incident light.
25
[0081] Theprotrusions 46 and the depressions 47 are
arranged alternately in both X and Y directions, forming a
square lattice. However, the protrusions 46 and the
depressions 47 may be arranged to form a triangle or hexagonal
lattice. For a structure that absorbs the first light
incident on the first optical surface but does not emit
diffraction light, the protrusions 46 and the depressions 47
may be arranged irregularly on the base surface 41a.
[0082] Theprotrusions 46 of the uneven structure portion
40 are semielliptical. Alternatively, the protrusions 46 may
have the shape of a rectangular prism or other polygonal prism.
Further, the depressions 47 of the uneven structure portion 40
are defined by curved surfaces but may be defined by circular
or polygonal surfaces.
[0083] In order for the first component 11 to diffract or
absorb the first light, the pitch P3 is preferably between 200
nm and 2,000 nm, inclusive, more preferably between 200 nm and
600 nm, inclusive. The pitch P3 that is less than or equal to
the visible light region facilitates absorption of the first
light by the first component 11. This allows the section of
the display body 10 including the first component 11 to have a
lower reflectivity than the section surrounding the first
component 11, increasing the visibility of the first
information formed by the first component 11.
[0084] The first components 11 described referring to
Figs. 6, 7 and 9 are uneven structures having protrusions
arranged at the predetermined pitch. However, as long as the
average value of the pitch P2 and the average value of the
pitch P3 are within the respective preferable ranges described
above, the minute uneven structures do not have be strictly
uniform and may be irregular.
[0085] Theplate portion 41 shown in Fig. 5 and the uneven
structure portions 40 shown in Figs. 6 to 9 may be made of
quartz. However, other inorganic materials that transmit
visible light or organic materials that transmit visible light
26
may be used. The inorganic material may be titanium oxide or
magnesium fluoride, and the organic material may be acrylic
resins including urethane-modified acrylic resin and epoxymodified
acrylic resin, epoxy resins, and other resins. The
plate portion 41 shown in Fig. 5, the uneven structure
portions 40 shown in Figs. 6 to 9, and the uneven structure
portion 21 of the third component 13 may be made of the same
material or different materials.
[0086] When the uneven structure portion 40 is made of an
inorganic material, the uneven structure portion 40 may be
formed by chemically or physically etching a substrate of the
inorganic material. When the uneven structure portion 40 is
made of a resin, the uneven structure portion 40 may be formed
by transferring the shape of an original plate to the resin
before hardening. The plate portion 41 shown in Fig. 5 may be
the substrate itself, or may be formed by chemically or
physically etching the substrate. Alternatively, the plate
portion 41 shown in Fig. 5 may be formed simply by applying a
resin, or may be formed by transferring the shape of an
original plate to the applied resin before hardening.
[0087] The first components 11 described referring to
Figs. 6 to 9 may have a metal layer that is entirely or partly
formed on the section of the first component 11 that forms the
front surface 10a of the display body 10. For example, the
first component 11 described referring to Fig. 6 may have a
metal layer that at least partially covering the section of
the base surface 41a that is free of the protrusions 43, the
top surfaces 43a of allprotrusions 43, and the side surfaces
43b of allprotrusions 43. The first component 11 described
referring to Fig. 7 may include a metal layer that at least
partially covers the surfaces of the protrusions 44.
[0088] The first component 11 described referring to Fig.
8 may have a metal layer that at least partially covers the
surfaces of the protrusions 45 and the section of the base
surface 41a that is free of the protrusions 45. The first
27
component 11 described referring to Fig. 9 may have a metal
layer that at least partially covers the section of the base
surface 41a that is free of protrusions 46 and the depressions
47, the surfaces of allprotrusions 46, and all surfaces
defining the depressions 47. When the first components 11
described referring to Figs. 6 to 9 each include a metal layer,
the surface of the metal layer forms a part of the front
surface 10a of the display body 10.
[0089] Forming a metal layer increases the light
reflectivity of the first optical surface, allowing the first
information formed by the first component 11 to be easily
perceived by the observer of the display body 10.
[0090] In order for the first component 11 to cause
reflection, diffraction, scattering, absorption, or
interference of light, the thickness of the metal layer of the
first component 11 is preferably between 20 nm and 100 nm,
inclusive, more preferably between 40 nm and 60 nm, inclusive.
The metal layer may be made of aluminum, for example. Further,
the metal layer may be made of gold, silver, or titanium
nitride.
[0091] The metal layer may be formed by physical vapor
deposition, such as vacuum deposition or sputtering. When the
metal layer is made of the same material as the metal layer 22
of the third component 13, the metal layer 22 of the third
component 13 and the metal layer of the first component 11 may
be formed simultaneously by physical vapor deposition.
In a similar manner as the first component 11 described
referring Fig. 9, the first components 11 described referring
to Figs. 6 to 8 may have a protective layer covering the
uneven structure portion 40.
[0092] The first component 11 may be an optical component
that forms first information using light reflection, an
optical component that forms first information using light
diffraction, or an optical component that forms first
information using scattering of light. Further, the first
28
component 11 may be an optical component that forms first
information using light absorption, or an optical component
that forms first information using light interference. In
addition, the first component 11 may include two or more of
such optical components.
[0093] The first component 11 forms first information
through reflection, diffraction, scattering, absorption, or
interference of the first light. Such reflection, diffraction,
scattering, absorption, or interference caused by the first
component 11 converts the first light into the light having
modified intensity, wavelengths, and observation angle. The
difference between this light and the light that is created by
the optical effect of the other section allows the observer of
the display body 10 to recognize the first information. On
the other hand, the third display elements 13a display second
information using the light having a certain color resulting
from the surface plasmon excitation caused by the second light.
This facilitates recognizing the difference between the first
information and the second information, helping the observer
of the display body 10 to correctly recognize multiple pieces
of information displayed by the display body 10.
[0094] [Front Surface of Display Body]
Referring to Figs. 10 and 11, the front surface 10a of
the display body 10 is now described. An example of the
display body 10 is described below in which the first
component 11 is the optical component described referring to
Fig. 7, and the second component 12 is the optical component
described referring to Fig. 8. Fig. 10 shows a part of the
cross-sectional structure of the second component 12 and a
part of the cross-sectional structure of the third component
13 in the cross-sectional structure of the display body 10.
Fig. 11 shows the cross-sectional structure of a section of
the first component 11 that includes a fourth component 14 in
the cross-sectional structure of the display body 10.
29
[0095] As shown in Fig. 10, the second component 12 of
the display body 10 includes a plate portion 41 and
protrusions 45 projecting from the base surface 41a of the
plate portion 41. The plate portion 41 and the protrusions 45
form an uneven structure portion 40. The second component 12
also includes a metal layer 48 covering the surfaces of all
protrusions 45 and the section of the base surface 41a that is
free of the protrusions 45. The front surface 48a of the
metal layer 48 forms a part of the front surface 10a of the
display body 10 and also forms the first optical surface of
the second component 12.
[0096] The third component 13 of the display body 10
includes an uneven structure portion 21 and a metal layer 22.
The uneven structure portion 21 includes a plate portion 31
and a plurality of protrusions 32, and the metal layer 22
covers top surfaces 32a of the protrusions 32 and the section
of a base surface 31a of the plate portion 31 that is free of
the protrusions 32. In the third component 13, the front
surface 22a of the metal layer 22 and the side surfaces 32b of
the protrusions 32 form the front surface 10a of the display
body 10. The front surface 22a of the metal layer 22 on the
top surface 32a of eachprotrusion 32 and the front surface 22a
of the metal layer 22 on the base surface 31a form the second
optical surface that emits second information.
[0097] In the display body 10, the uneven structure
portion 21 of the third component 13 and the uneven structure
portion 40 of the second component 12 are formed by a single
substrate. In addition, the metal layer 22 of the third
component 13 and the metal layer 48 of the second component 12
are made of the same material.
[0098] Since the second component 12 and the third
component 13 each include a part of the front surface 10a of
the display body 10 as the optical surface, the relative
positioning between the second component 12 and the third
component 13 may be achieved by positioning the second
30
component 12 in the substrate and positioning the third
component 13 in the substrate using a common method.
Alternatively, the second and third components 12 and 13 may
be formed using the same type of technique.
[0099] For example, the shape of an original plate
including a die for shaping the second component 12 and a die
for shaping the third component 13 may be transferred to a
substrate, or a substrate may be etched using a single mask
that includes a mask for forming the second component 12 and a
mask for forming the third component 13.
[0100] Alternatively, the shape of an original plate for
forming the second component 12 may be transferred to a
substrate, and then the shape of an original plate for forming
the third component 13 may be transferred to the substrate, or
a substrate may be etched using a mask for forming the second
component 12 and then etched using a mask for forming the
third component 13.
[0101] Such a method increases the accuracy of the
position of the third component 13 relative to the second
component 12 and thus the accuracy of the display position of
the second information relative to the display position of the
first information.
[0102] When the second component 12 and the third
component 13 are formed simultaneously, the number of steps
required to manufacture the display body 10 including the
second and third components 12 and 13 is the same as the
number of steps required to manufacture a display body having
only the second component 12. The display body 10 including
the second and third components 12 and 13 is manufactured
without increasing the number of manufacturing steps or the
manufacturing costs.
[0103] The display body 10 does not include through-holes
extending through the front surface 10a and the back surface
10b of the display body 10 to function as an optical component
for displaying information. The display body 10 thus has a
31
higher mechanical strength than a display body having throughholes.
The first component 11 and the third component 13 have
similar advantages as the second component 12 and the third
component 13.
[0104] As shown in Fig. 11, the first component 11 of the
display body 10 includes aplate portion 41 and a plurality of
protrusions 44 projecting from the base surface 41a of the
plate portion 41. The plate portion 41 and the protrusions 44
form an uneven structure portion 40. The first component 11
includes a metal layer 49 covering the surfaces of all
protrusions 44. The front surface 49a of the metal layer 49
forms a part of the front surface 10a of the display body 10
and also forms the first optical surface of the first
component 11.
[0105] Each fourth component 14 of the display body 10
includes an uneven structure portion 21 and a metal layer 22.
The uneven structure portion 21 includes a plate portion 31
and a plurality of protrusions 32, and the metal layer 22
covers the top surfaces 32a of the protrusions 32 and the
section of the base surface 31a of the plate portion 31 that
is free of the protrusions 32. In the fourth component 14,
the front surface 22a of the metal layer 22 and the side
surfaces 32b of the protrusions 32 form the front surface 10a
of the display body 10. The front surface 22a of the metal
layer 22 on the top surface 32a of each protrusion 32 and the
front surface 22a of the metal layer 22 on the base surface
31a form the second optical surface that emits second
information.
[0106] In the display body 10, the uneven structure
portion 21 of the fourth component 14 and the uneven structure
portion 40 of the first component 11 are formed by a single
substrate. In addition, the metal layer 22 of the fourth
component 14 and the metal layer 49 of the first component 11
are made of the same material.
32
[0107] The first component 11 and the fourth component 14
in the display body 10 have similar advantages as the second
component 12 and the third component 13 described above. The
first component 11 surrounds the fourth component 14, which is
small enough to be indiscernible to the observer of the
display body 10 with the naked eye. Thus, unless the observer
of the display body 10 knows that the display body 10 has the
fourth component 14, the observer is unlikely to notice the
fourth component 14 in the display body 10.
[0108] Moreover, the first component 11 forms the first
information on the observation side by converting the light
incident on the front surface 10a into diffraction light.
Such optical effect of the first component 11 helps to keep
the observer who does not know the presence of the fourth
component 14 in the display body 10 from noticing the fourth
component 14 in the display body 10.The structure of the
display body 10 increases the difficulty of counterfeiting the
display body 10 for a person who attempts to counterfeit,
while allowing a person who knows the presence of the fourth
component 14 to easily authenticate the display body 10 by
checking for the fourth component 14.
[0109] [Display Body Observation Method]
Referring to Figs. 12 to 14, the method for observing
the display body 10 is now described. In the following
example, the display body 10 to be observed is attached to a
verification subject of which the authenticity requires
verification. The first component 11 may be the optical
component described referring to Fig. 7, and the second
component 12 may be the optical component described referring
to Fig. 8.
[0110] As shown in Fig. 12, the display body 10 is
attached to a verification subject 50. The verification
subject 50 may be a substrate through which light passes to
the display body 10. Alternatively, a section of the
33
verification subject 50 including at least the section to
which the display body 10 is attached may be formed by a
substrate that transmits light to the display body 10.
Further, the display body 10 may be attached to the
verification subject 50 such that light is directly incident
on the display body 10.
[0111] The method for observing the display body 10
includes a step of causing first light to be incident on the
front surface 10a of the display body 10 and a step of
observing first information formed by the first optical
component from the first light incident on the front surface
10a. The method for observing the display body 10 also
includes a step of causing second light to be incident on the
back surface 10b of the display body 10 and a step of
observing second information formed by the second optical
component from the second light incident on the back surface
10b. The step of observing first information and the step of
observing second information are performed by an observer.
However, these steps may be performed by an apparatus that is
capable of detecting the first information and the second
information formed by the display body 10.
[0112] In the step of causing the first light to be
incident, a light source LS located on the observation side
emits white light as first light IL1. The first light IL1 is
incident on the front surface 10a of the display body 10 from
the observation side. The first component 11 of the display
body 10 diffracts the first light IL1 incident on the front
surface 10a of the display body 10 toward the observation side,
thereby emitting diffraction light as reflection light RL.
That is, the first component 11 forms first information by
diffracting the first light IL1. The second component 12
scatters the first light IL1 incident on the front surface 10a
of the display body 10 toward the observation side, thereby
emitting scattered light as reflection light RL. That is, the
second component 12 forms first information by scattering the
34
first light IL1.
In contrast, the third component 13 does not form
predetermined second information on the observation side when
the first light IL1 is incident on the front surface 10a of
the display body 10.
[0113] Consequently, in the step of observing first
information, the observer OB visually perceives the first
information formed by the first component 11 and the first
information formed by the second component 12 but does not
perceive the second information of the third component 13.
[0114] As shown in Fig. 13, in the step of causing second
light to be incident, the light source LS is located on the
side opposite to the observation side with respect to the back
surface 10b of the display body 10, and second light IL2 is
incident on the back surface 10b from the side opposite to the
observation side with respect to the back surface 10b. The
second light IL2 transmitted through the back surface 10b
excites surface plasmons on the third component 13 so that the
third component 13 emits transmitted light TL having a
predetermined color that differs from the color of the second
light IL2. In other words, the third component 13 forms
second information by converting the second light IL2 into the
transmitted light TL that differs from the second light IL2 in
color.
[0115] The first component 11 includes the metal layer 48,
which forms a part of the front surface 10a of the display
body 10, and the second component 12 includes the metal layer
49, which forms a part of the front surface 10a of the display
body 10. Thus, the first and second components 11 and 12 do
not transmit the second light IL2 incident on the back surface
10b of the display body 10 to the front surface 10a of the
display body 10. Alternatively, the first and second
components 11 and 12 may transmit part of the second light IL2
but still do not form the predetermined first information.
[0116] Consequently, in the step of observing second
35
information, the observer OB visually perceives the second
information formed by the third component 13 but does not
perceive the first information of the first component 11 or
the first information of the second component 12.
[0117] As shown in Fig. 14, in the step of observing
second information, the display body 10 may be observed under
magnification. The observer OB may observe the second
information formed by the display body 10 by magnifying the
display body 10 using an optical microscope LM. Of the pieces
of second information formed by the display body 10, the piece
of second information formed by a fourth component 14 may be
magnified to the size that is visible by the observer OB.
This allows the observer OB to observe the second information
formed by the fourth component 14.
[0118] The advantages of the embodiments described above
are now described.
(1) Since both the first and second optical components
include parts of the front surface 10a as optical surfaces,
relative positioning between the first optical components and
the second optical componentscan be set by positioning the
first components in the substrate and positioning the second
optical components in the substrate using a common method.
Alternatively, the first and second optical components can be
formed using the same type of technique. Such a structure
increases the accuracy of the position of the second optical
components relative to the first optical components and thus
the accuracy of the display position of the second information
relative to the display position of the first information.
[0119] (2) The size of each fourth component 14 relative
to the size of the first component 11 is small enough so that
the fourth component 14 is likely to be indiscernible when the
reflection light from the front surface 10a of the display
body 10 is observed.
[0120] (3) Since the third component 13 and the fourth
components 14 each form second information having a
36
predetermined color, the difference between the light having
the predetermined color and the other section allows the
observer OB of the display body 10 to recognize the second
information. Thus, the difference between the section of the
second information and the other section is easily recognized.
[0121] (4) The protrusions of the first optical
components and the protrusions of the second optical
components form parts of the front surface 10a of the display
body 10. Thus, even when the first and second optical
components each have a complex structure of protrusions, the
display position of the second information relative to the
display position of the first information is set with high
accuracy.
[0122] The embodiments described above may be modified as
follows.
[Print Layer]
As will be described below referring to Figs. 15 to 20,
the display body 10 may include a print layer.
[0123] As shown in Fig. 15, the display body 10 may
include a print layer 60, which has a plurality of print
portions 61 and forms third information displayed on the
observation side of the display body 10. Each print portion
61 is undulated and has at least one curve. In a plan view of
the front surface 10a of the display body 10, the print
portions 61 are arranged at predetermined intervals in one
direction.
[0124] In a plan view of the front surface 10a of the
display body 10, the print portions 61 include print portions
61 that overlap with first display elements 11a of the first
component 11, print portions 61 that overlap with second
display elements 12a of the second component 12, and print
portions 61 that overlap with third display elements 13a of
the third component 13. In a plan view of the front surface
10a of the display body 10, the print portions 61 that overlap
37
with first display elements 11a may include a section that
overlaps with a fourth element surrounded by a first display
element 11a.
[0125] In a plan view of the front surface 10a of the
display body 10, the print portions 61 include print portions
61 that do not overlap with any of the first to third
components 11 to 13. Alternatively, all of the print portions
61 may overlap with one of the first to third components 11 to
13.
[0126] The print layer 60 forms a pattern of undulated
shapes, which is an example of a guilloche pattern.
Alternatively, the print layer 60 may form a guilloche pattern
of arcuate shapes or a guilloche pattern of circular shapes.
Further, the print layer 60 may form a guilloche pattern in
which two or more of an undulated shape, an arcuate shape, and
a circular shape are combined. The print layer 60 may form a
pattern of geometric shapes other than undulated, arcuate, or
circular shapes. That is, the image displayed by the print
layer 60 as third information may be any predetermined pattern.
[0127] As shown in Fig. 16, the display body 10 may
include a print layer 70 that forms information including at
least a letter or a number, instead of the predetermined
pattern as described above. Such information may be
identification information, such as a card number or a lot
number. That is, the print layer 70 displays information as
an image that includes at least a predetermined letter ora
predetermined number.
[0128] The print layer 70 has a plurality of print
portions 71 including a first section 71a, a second section
71b, and a third section 71c. In a plan view of the front
surface 10a of the display body 10, the print portions 71 are
arranged side by side in a predetermined direction in the
display body 10. Each print portion 71 may represent one
number. Of the print portions 71, the first section 71a
represents the number 1, the second section 71b represents the
38
number 2, and the third section 71c represents the number 3.
[0129] In a plan view of the front surface 10a of the
display body 10, of the three print portions 71, the first
section 71a overlaps with first display elements 11a of the
first component 11, the second section 71b overlaps with
second display elements 12a of the second component 12, and
the third section 71c overlaps with third display elements 13a
of the third component 13. In a plan view of the front
surface 10a of the display body 10, the section of the first
section 71a that overlaps with a first display element 11a may
overlap with a fourth component inside the first display
element 11a.
[0130] In a plan view of the front surface 10a of the
display body 10, the print portions 71 may include a print
portion 71 that does not overlap with any of the first to
third components 11 to 13.
[0131] The image displayed by the print layer 60 or 70 as
third information is not limited to the illustration,
letter,or number described above, and may be a graphic, a
symbol, and a combination of at least two or more of an
illustration, a letter, a number, a graphic, and a symbol.
[0132] In the structure described above, the display body
10 includes the print layer, which forms third information,
and thus achieves intricate representation of the pieces of
informationand overlapping between pieces of information.
[0133] Referring to Figs. 17 to 20, the cross-sectional
structure of the display body 10 is now described.
The print layer of the display body 10 described
referring to Fig. 15 and the print layer of the display body
10 described referring to Fig. 16 display different images but
are located at the same position in the thickness direction in
the display bodies 10.
[0134] Thus, the cross-sectional structure of the display
body 10 of Fig. 15 is described below, and the cross-sectional
structure of the display body 10 of Fig. 16 is not described.
39
In the following example, the second component 12, which is an
example of the first optical component, is the reflective
diffraction grating described referring to Fig. 7.
[0135] Figs. 17 to 20 each show a cross-sectional
structure in which the back surface 10b of the display body 10
and the observation side of the display body 10 are located on
opposite sides of the front surface 10a. In the following
description, the effects of the display bodies 10 that are
achieved when white light is incident on the display bodies 10
are described.
[0136] As shown in Fig. 17, the second component 12 of
the display body 10 includes an uneven structure portion 40
formed by a plate portion 41 and a plurality of protrusions 44.
The second component 12 also includes a metal layer 81
covering the surfaces of all protrusions 44. The front
surface 81a of the metal layer 81 forms a part of the front
surface 10a of the display body 10 and also forms the first
optical surface of the second component 12.
[0137] The third component 13 of the display body 10
includes an uneven structure portion 21 and a metal layer 22.
The uneven structure portion 21 includes a plate portion 31
and a plurality of protrusions 32, and the metal layer 22
covers the top surfaces 32a of the protrusions 32 and the
section of the base surface 31a of the plate portion 31 that
is free of the protrusions 32.
[0138] In the third component 13, the front surface 22a
of the metal layer 22 and the side surfaces 32b of the
protrusions 32 form the front surface 10a of the display body
10. The front surface 22a of the metal layer 22 on the top
surface 32a of each protrusion 32 and the front surface 22a of
the metal layer 22 on the base surface 31a form the second
optical surface of the third component 13.
[0139] In the display body 10, the uneven structure
portion 21 of the third component 13 and the uneven structure
portion 40 of the second component 12 are formed by a single
40
substrate 10c. In the uneven structure portion 21 of the
third component 13, the surface opposite to the base surface
31a forms a part of the back surface 10b of the display body
10. In the uneven structure portion 40 of the second
component 12, the surface opposite to the front surfaces of
the protrusions 44 forms a part of the back surface 10b of the
display body 10. The metal layer 22 of the third component 13
and the metal layer 81 of the second component 12 are
preferably made of the same material but may be made of
different materials.
[0140] A plurality of print portions 61, which forms a
print layer 60, is formed on the back surface 10b of the
display body 10. That is, the print layer 60 is located on
the side of the back surface 10b of the display body 10 on
which the second light is incident. The print portions 61 do
not transmit visible light and include print portions 61 that
overlap with the second component 12 and print portions 61
that overlap with the third component 13 as viewed in the
thickness direction of the display body 10.
[0141] The print layer 60 may be made of ink including
predetermined pigment or dye and formed using various printing
methods, such as gravure printing, offset printing, and screen
printing.
[0142] In the section of the second component 12 that
overlaps with the print portions 61 as viewed in the thickness
direction of the display body 10, the print portion 61 limits
transmission of the second light from the back surface 10b to
the front surface 10a of the display body 10. Accordingly,
when the metal layer 81 of the second component 12 transmits
light, the section of the second component 12 that overlaps
with the print portions 61 and the section of the second
component 12 that does not overlap with the print portion 61
provide high contrast in the image perceived by the observer
of the display body 10 . This facilitates recognizing the
information displayed by the print portions 61 in the
41
information displayed by the second component 12.
[0143] In the section of the third component 13 that
overlaps withprint portions 61 as viewed in the thickness
direction of the display body 10, the print portions 61 limit
transmission of the second light from the back surface 10b to
the front surface 10a of the display body 10. Thus, in the
sections of the third component 13 that overlapwith the print
portions 61, a lower amount of light is created by surface
plasmon excitation, reducing the likelihood of visual
perception of the light from the third component 13.
Accordingly, the section of the third component 13 that
overlaps with the print portions 61 and the section of the
third component 13 that does not overlap with the print
portions 61 provide high contrast in the image perceived by
the observer of the display body 10. This facilitates
recognizing the information displayed by the print portions 61
in the information displayed by the third component 13.
[0144] When the observer directly faces the front side of
the display body 10, the section that overlaps with the print
portions 61 emits the smallest amount of light in the third
component 13, facilitating the visual perception of the print
portions 61.
[0145] The print layer 60 may be located on the side of
the front surface 10a of the display body 10 on which the
first light is incident. As shown in Fig. 18, the display
body 10 may include a covered surface 10d, which corresponds
to the front surface 10a of the display body 10. A
transparent plastic layer 82 is formed over the entire covered
surface 10d, covering the second component 12 and the third
component 13. The transparent plastic layer 82 is made of a
plastic capable of transmitting light. The surface of the
transparent plastic layer 82 that is opposite to the surface
in contact with the covered surface 10d of the display body 10
is a front surface 82a, on which a plurality of print portions
61 are formed.
42
[0146] The transparent plastic layer 82 may have
adhesiveness for attaching the display body 10 to an object
such as a verification subject. When the transparent plastic
layer 82 does not have adhesiveness, another layer having
adhesiveness may be formed on the front surface 82a of the
transparent plastic layer 82 or the back surface 10b of the
display body 10.
[0147] Theprint portions 61 include print portions 61
that overlap with the second component 12 and print portions
61 that overlap with the third component 13 as viewed in the
thickness direction of the display body 10.
In the sections of the second component 12 that extend
under print portions 61 as viewed in the thickness direction
of the display body 10, the print portions 61 limit the first
light incident on the second component 12. In the diffraction
light emitted by the second component 12, the diffraction
light directed toward the print portions 61 is less likely to
be emitted to the observation side of the display body 10 due
to the print portions 61.
[0148] Such a structure reduces the area on the
observation side to which the diffraction light is emitted
from the second component 12 as compared with a structure that
does not include print portions 61 overlapping with the second
component 12 as viewed in the thickness direction of the
display body 10. This limits visual perception of the
diffraction light that is emitted at predetermined angles.
[0149] In the section of the third component 13 that
overlaps withprint portions 61 as viewed in the thickness
direction of the display body 10, the print portions 61 reduce
the likelihood that the light emitted from the third component
13 by surface plasmon excitation will be emitted to the
observation side. This reduces the amount of light emitted
from the section of the third component 13 extending under the
print portions 61, hindering visual perception of the section
extending under the print portions 61.
43
[0150] Theprint portions of the print layer 60 are not
limited to the print portions that do not transmit visible
light as described above, and may be print portions that
transmit part of visible light.
[0151] As shown in Fig. 19, in the structure described
referring to Fig. 17, the print layer 60 may include a
plurality of print portions 62 that transmits part of visible
light. The print portions 62 include print portions 62 that
overlap with the second component 12 and print portions 62
that overlap with the third component 13 as viewed in the
thickness direction of the display body 10.
[0152] When the metal layer 81 of the second component 12
transmits light, the sections of the second component 12 that
overlapwithprint portions 62 as viewed in the thickness
direction of the display body 10 emit the light that is
transmitted through the print portions 62 and has
predetermined wavelengths and the diffraction light that is
diffracted by the second component 12. Consequently, the
light transmitted through the print portions 62 and the
diffraction light arevisually perceived. This structure
allows the pattern of the print portions 62 and the pattern of
the diffraction light to be viewed superimposed.
[0153] In the section of the third component 13 that
overlaps withprint portion 62 as viewed in the thickness
direction of the display body 10, part of the light
transmitted through the print portions 62 is used for plasmon
excitation on the third component 13, and the remaining part
of the light is transmitted through the third component 13.
[0154] When the light transmitted through the print
portions 62 differs in color from the light emitted by plasmon
excitation on the third component 13, the emitted light has a
mixed color of the color of the light transmitted through the
print portions 62 and the color of the light transmitted
through the third component 13.
[0155] Further, a print layer 60 including print portions
44
62 that transmit visible light may be used in the structure
described referring to Fig. 18. That is, as shown in Fig. 20,
a print layer 60 including a plurality of print portions 62
may be formed on the front surface 82a of the transparent
plastic layer 82. As viewed in the thickness direction of the
display body 10, the print portions 62 include print portions
62 that overlap with the second component 12 and print
portions 62 that overlap with the third component 13.
[0156] Part of the diffraction light emitted by the
second component 12 is directed toward print portions 62.
When the diffraction light directed toward the print portions
62 has wavelengths that can pass through the print portions 62,
the diffraction light is transmitted through the print
portions 62 and emitted to the observation side. In contrast,
when the diffraction light directed toward the print portions
62 has wavelengths that cannot pass through the print portions
62, the diffraction light is not emitted to the observation
side.
[0157] In the sections of the third component 13 that
overlaps withprint portions 62 as viewed in the thickness
direction of the display body 10, part of the incident light
is used for surface plasmon excitation, and the remaining part
of the light is transmitted through the third component 13.
[0158] When the wavelength of the light that can pass
through the print portions 62 is the same as the wavelength of
the light created by surface plasmon excitation on the third
component 13, the light created by surface plasmon excitation
is not absorbed by the print portions 62 and transmitted.
Thus, the print portions 62 emit light having the same
wavelength as the light created by surface plasmon excitation.
In contrast, when the wavelength of the light that can pass
through the print portions 62 differs from the wavelength of
the light created by surface plasmon excitation on the third
component 13, the print portions 62 absorb certain wavelengths
in the light incident on the third component 13 and transmit
45
the other wavelengths to the observation side.
The display body 10 of Fig. 16 that includes the print
layer 70 has similar advantages as the display body 10 that
includes the print layer 60.
[0159] In a structure in which the display body 10
includes the transparent plastic layer 82, that is, the
structure described referring to Fig. 18 and the structure
described referring to Fig. 20, print layers may be formed on
both of the front surface 82a of the transparent plastic layer
82 and the back surface 10b of the substrate 10c.
[0160] For the display body 10 described referring to Fig.
17, the side on the back surface 10b of the display body 10
that is opposite to the front surface 10a may serve as the
observation side of the display body 10.
That is, as shown in Fig. 21, the second component 12
may include a metal layer 81 having a back surface 81b, which
is in contact with the substrate 10c, and a front surface 81a,
which is opposite to the back surface 81b. The back surface
81b of the metal layer 81 forms a part of the first surface on
which the first light is incident and also forms the first
optical surface of the second component 12.
[0161] The third component 13 includes a metal layer 22
having a back surface 22b, which is in contact with the
substrate 10c, and a front surface 22a, which is opposite to
the back surface 22b. The front surface 22a of the metal
layer 22 forms a part of the second surface on which the
second light is incident, and the back surface 22b of the
metal layer 22 forms the second optical surface of the third
component 13.
[0162] A plurality of print portions 63, which forms a
print layer 60, is formed on the back surface 10b of the
display body 10. That is, the print layer 60 is located on
the side of the back surface 10b of the display body 10 on
which the first light is incident. The print portions 63 do
not transmit visible light and include print portions 63 that
46
overlap with the second component 12 and print portions 63
that overlap with the third component 13 as viewed in the
thickness direction of the display body 10.
[0163] Such a print layer 60 has similar advantages as
the print layer 60 of the display body 10 described referring
to Fig. 18.
[0164] For the display body 10 described referring to Fig.
18, the side on the back surface 10b of the display body 10
that is opposite to the front surface 10a may serve as the
observation side of the display body 10.
[0165] That is, as shown in Fig. 22, the display body 10
may include a transparent plastic layer 82 having a front
surface 82a, on which a plurality of print portions 63 of a
print layer 60 is formed. In the same manner as the display
body 10 described referring to Fig. 21, the back surface 81b
of the metal layer 81 of the display body 10 forms a part of
the first surface and also forms the first optical surface of
the second component 12. The front surface 22a of the metal
layer 22 of the display body 10 forms a part of the second
surface, and the back surface 22b of the metal layer 22 forms
the second optical surface of the third component 13.
[0166] Such a print layer 60 has similar advantages as
the print layer 60 of the display body 10 described referring
to Fig. 17.
[0167] In the display body 10 described referring to Fig.
21, the print portions of the print layer 60 may transmit part
of visible light.
[0168] That is, as shown in Fig. 23, the print layer 60
may include a plurality of print portions 64, which transmits
part of visible light and is formed on the back surface 10b of
the display body 10. The print portions 64 include print
portions 64 that overlap with the second component 12 and
print portions 64 that overlap with the third component 13 as
viewed in the thickness direction of the display body 10.
[0169] Such a print layer 60 has similar advantages as
47
the print layer 60 of the display body 10 described referring
to Fig. 20.
[0170] In the display body 10 described referring to Fig.
22, the print portions of print layer 60 may transmit part of
visible light.
[0171] That is, as shown in Fig. 24, the print layer 60
may include a plurality of print portions 64, which transmits
part of visible light and is formed on the front surface 82a
of the transparent plastic layer 82. As viewed in the
thickness direction of the display body 10, the print portions
64 include print portions 64 that overlap withthe second
component 12 and print portions 64 that overlap withthe third
component 13.
[0172] Such a print layer 60 has similar advantages as
the print layer 60 of the display body 10 described referring
to Fig. 19.
[0173] In each structure having a print layer 60, the
second component 12 is not limited to the reflective
diffraction grating described above, and may be one of the
structures described referring to Figs. 5, 6, 8 and 9.
[0174] The print portions forming one print layer 60 may
include print portions that transmit part of visible light and
print portions that do not transmit visible light.
[0175] As shown in Fig. 25, when the display body 10
includes a print layer 60 that displays a pattern of geometric
shapes, such as a guilloche pattern described above, a
verification subject 50 to which the display body 10 is
attached may include a print layer 51. The print layer 51
includes a plurality of print portions 52, and in a plan view
of the front surface 10a of the display body 10, each print
portion 52 is preferably connected to one of the print
portions formed on the display body 10. In this case, the
print layer 60 of the display body 10 and the print layer 51
of the verification subject 50 form a common guilloche pattern.
Alternatively, the print layer 60 of the display body 10 and
48
the print layer 51 of the verification subject 50 may display
a common guilloche pattern without being connected. Further,
the print layer 60 of the display body 10 and the print layer
51 of the verification subject 50 may be disconnected and
display different guilloche patterns.
[0176] [Other Modifications]
In the step of causing the first light to be incident,
the light incident on the display body 10 does not have to be
white light as long as the light incident on the display body
10 includes light that causes optical effects of the first
component 11 and the second component 12.
[0177] In the step of causing the second light to be
incident, the light incident on the display body 10 does not
have to be white light as long as the light incident on the
display body 10 includes light of which the color is
changeable by the plasmon structures of the third component 13
and the fourth component 14.
[0178] As long as the section of the first component 11
that forms the front surface 10a of the display body 10 is
capable of forming first information using the first light,
the pitch P2 may be a predetermined length that is less than
200 nm, or a predetermined length that is greater than 2,000
nm.
[0179] As long as the section of the first component 11
that forms the front surface 10a of the display body 10 is
capable of forming first information using the first light,
the pitch P3 may be a predetermined length that is less than
200 nm, or a predetermined length that is greater than 2,000
nm.
[0180] The first component 11 does not have to include an
uneven structure. For example, the first component 11 may
consist only of a plate portion having a substantially flat
surface that reflects the first light toward the observation
side. That is, the first component 11 described referring to
49
Fig. 5 may be a structure that includes only the plate
portion41 and forms first information by reflecting the first
light received on the base surface 41a.
[0181] The third display elements 13a of the third
component 13 may include two types of display elements, first
display elements and second display elements. The first
display elements differ from the second display elements in
the color of transmitted light. The color of transmitted
light depends on the state of surface plasmons formed on the
plasmon structure in each display element. A change in at
least one of the following conditions changes the state of
surface plasmons formed on the metal layer 22.
[0182] Each first display element includes a first
plasmon structure, and each second display element includes a
second plasmon structure. The first plasmon structure differs
from the second plasmon structure in at least one of the pitch
P1 of the protrusions 32 on the base surface 31a of the plate
portion 31, the distance D between the base surface 31a and
the imaginary plane S, the arrangement of the protrusions 32
on the base surface 31a, the thickness M of the metal layer 22,
the refractive index of the transparent plastic layer 82, and
the material forming the metal layer 22. The difference
causes the state of the surface plasmons excited by the first
plasmon structure to differ from the state of the surface
plasmons excited by the second plasmon structure.
[0183] The third component 13 including the first plasmon
structures that emit light having a first color and the second
plasmon structures that emit light having a second color has
the following advantages.
[0184] (5) Since the third component 13 displays a mixed
color of the first and second colors, the third component 13
can display a wider variety of colors than a component that
includes either the first plasmon structuresor the second
plasmon structures. In addition, the first display elements
differ from the second display elements in the state of
50
surface plasmon excitation, allowing the second optical
component to display intricate second information as compared
with a structure only including elements that are identical in
the state of surface plasmon excitation.
[0185] The third display elements 13a of the third
component 13 may include three or more types of display
elements that differ from one another in the color of
transmitted light.
Further, each third display element 13a of the third
component 13 may include two or more sections that transmit
light of different colors.
[0186] The third component 13 and the fourth components
14 may transmit white light. In each of the third component
13 and the fourth components 14, when the protrusions 32 are
at random pitches P1 or vary in height, for example, the state
of surface plasmons on an interface 23, which is the minimum
unit of the plasmon structure, differs from the state on
another interface 23. Consequently, the light transmitted
through the third component 13 and the fourth components 14
will be white in color.
[0187] As compared withprotrusions that are arranged
regularly, protrusions 32 that are arranged irregularly tend
to provide various states of surface plasmon excitation in
each of the third component 13 and the fourth component 14.
Each of the light transmitted through the third component 13
and the light transmitted through the fourth component 14
tends to be a mixture of multiple light beams of different
wavelengths.
[0188] As long as surface plasmon excitation occurs on
the metal layer 22, the pitch P1 may be a predetermined length
that is less than 100 nm, or a predetermined length that is
greater than 600 nm.
[0189] As long as surface plasmon excitation occurs on
the metal layer 22, the thickness of the metal layer 22 may be
a predetermined thickness that is less than 20 nm, or a
51
predetermined thickness that is greater than 100 nm.
[0190] As long as surface plasmon excitation occurs on
the metal layer 22, the distance between the base surface 31a
and the imaginary plane S may be a predetermined distance that
is less than 30 nm, or a predetermined distance that is
greater than 500 nm.
As long as surface plasmon excitation occurs on the
metal layer 22, the base surface 31a and the imaginary plane S
may form a predetermined angle.
[0191] The third component 13 and the fourth components
14 may emit transmitted light to the observation side. The
transmitted light has substantially the same wavelengths as
the second light that is incident on the back surface 10b of
the display body10, that is, the transmitted light has the
same color as the second light. Further, each of the third
component 13 and the fourth components 14 may include a
section that transmits the second light incident on the back
surface 10b of the display body 10, such as a section in which
the thickness of the metal layer 22 is small enough to
transmit the second light.
[0192] The uneven structure of the third component 13 and
the fourth components 14 may include a single plasmon
structure or two or more plasmon structures.
[0193] As shown in Fig. 26, a display body 90 may include
a first component 91 and a second component 92, which is
entirely surrounded by the first component 91. The second
component 92 includes parts of the front surface 90a of the
display body 90 as the second optical surface, and the first
component 91 includes the other part of the front surface 90a
of the display body 90 as the first optical surface.
[0194] The first component 91 is the optical component
that is described referring to Fig. 9 and forms first
information on the observation side by absorbing the first
light received on the first optical surface. The first
component 91 forms first information that is a black or dark
52
gray section of a rectangular shape excluding the second
component 92.
[0195] The second component 92 is the optical component
described referring to Figs. 3 and 4 and includes plasmon
structures. The second component 92 receives second light
transmitted through the back surface 90b of the display body
90, forms second information displayed on the observation side
from the second light, and emits the second information from
the second optical surface, which is a part of the front
surface 90a. The second information is the light transmitted
through the back surface 90b of the display body 90 and
differs from the second light in color.
[0196] In addition, the second component 92 absorbs the
first light received on the second optical surface to emit the
light that mimics the first information to the observation
side. The absorption by the second component 92 results in a
reduction in the light reflectivity of the second component 92
as compared with a structure that does not include protrusions
or depressions.
[0197] Accordingly, when the first light is incident on
the front surface 90a of the display body 90 and the second
component 92 is viewed in the direction of the normal to the
plate portion 31, the first component 91 displays third
information in black or dark gray on the observation side.
[0198] The second component 92 includes a plurality of
second display elements 92a. When the second light is
incident on the display body 90, the second display elements
92a form information of a predetermined color as the second
information, which is a combination of the letters O and
K.When the first light is incident on the display body 90, the
second component 92 emits light that has a black or dark gray
color and mimics the first information formed by the first
component 91.
[0199] The reflectivity of the second optical surface of
the second component 92 is substantially equal to the
53
reflectivity of the first optical surface of the first
component 91. The reflectivities are considered to be
substantially equal when the reflectivity of the second
optical surface is equal to the reflectivity of the first
optical surface and also when the difference between the
reflectivity of the second optical surface and the
reflectivity of the first optical surface is such that the
first information and the light emitted by the second optical
component are recognized as a single piece of information when
the reflected light from the front surface 90a is viewed.
[0200] As shown in Fig. 27, the display body 90 is
attached to a verification subject 100. The verification
subject 100 includes a substrate through which light passes to
the display body 90. Alternatively, a section of the
verification subject 100 including at least the section to
which the display body 90 is attached may be formed by a
substrate that transmits light to the display body 90.
Further, the display body 90 may be attached to the
verification subject 100 such that light is directly incident
on the display body 90.
[0201] In the step of causingthe first light to be
incident on the display body 90, a light source LS located on
the observation side emits white light as first light IL1.
The first light IL1 is incident on the front surface 90a of
the display body 90 from the observation side. Part of the
first light IL1 incident on the front surface 90a of the
display body 90 is received on the first optical surface and
absorbed by the first component 91 of the display body 90.
Other part of the first light IL1 incident on the front
surface 90a of the display body 90 is received on the second
optical surface and absorbed by the second component 92.
[0202] Consequently, in the step of observing first
information, the observer OB visually perceives, in reflection
light RL, one piece of information that is formed by the first
information displayed by the first component 91 and the light
54
emitted by the second component 92. The light emitted by the
second component 92 is indistinguishable by itself to the
observer OB. In addition, since the light emitted by the
second component 92 mimics the first information formed by the
first component 91, the light emitted by the second component
92 is unlikely to hinder the perception of the first
information.
[0203] As shown in Fig. 28, in the step of causing the
second light to be incident on the display body 90, the light
source LS is located on the side opposite to the observation
side with respect to the back surface 90b of the display body
90, and second light IL2 is incident on the back surface 90b
of the display body 90 from the side opposite to the
observation side with respect to the back surface 90b. The
second light IL2 transmitted through the back surface 90b
excites surface plasmons so that the second component 92 emits
transmitted light TL that differs from the second light IL2 in
color. In other words, the second component 92 forms
transmitted light as second information from the second light
IL2 and emits the transmitted light to the observation side.
The first component 91 does not display the first
information on the observation side when the second light IL2
is incident on the back surface 90b of the display body 90.
[0204] Consequently, in the step of observing second
information, the observer OB visually perceives the second
information formed by the second component 92 but does not
perceive the first information of the first component 91.
[0205] The display body 90 displays a single piece of
information formed by the first information and the light
emitted by the second component 92 when the first light IL1 is
incident, and displays the second information when the second
light IL2 is incident. This allows the observer OB to
authenticate the verification subject 100 by determining
whether the display body 90 has the second information, for
example.
55
[0206] The structure described above has the following
advantages.
(6) When the second optical surface receives the first
light, the second component 92 emits the light that mimics the
first information to the observation side. Thus, the light
emitted by the second component 92 is unlikely to hinder the
perception of the first information.
[0207] In each of the embodiments described above, the
section of the front surface 10a of the display body 10 other
than the first component 11, the second component 12, and the
third component 13 preferably functions as a fifth component,
in a similar manner as the display body 90 described referring
to Fig. 26. The fifth component forms first information, and
the light emitted by the third component 13 when the third
component 13 receives the first light preferably mimics the
first information.
[0208] The display body 90 may be structured such that,
when the first light is incident on the front surface 90a of
the display body 90, the color of the light emitted by the
first component 91 is substantially the same as the color of
the light emitted by the second component 92. Such a
structure still allows the light emitted by the second
component 92 to mimic the first information. The display body
90 may have any structure as long as the color of the
diffraction light emitted by the first component 91 is
substantially the same as the color of the diffraction light
emitted by the second component 92, for example.
[0209] The surface of the display body may include the
first optical surface, the second optical surface, and a
surface other than the first and second optical surfaces, as
is the case in the display body 10 of the embodiments.
Alternatively, the surface of the display body may include
only the first optical surface and the second optical surface,
as is the case in the display body 90 of the modification.
[0210] When a first optical component surrounds a second
56
optical component in the front surface 10a of the display
body10, the relationship between the area S1 and the area S2
may satisfy one of Expressions (2) and (3) below.
0.01 > S2/S1(Expression 2)
S2/S1 >0.4(Expression 3)
[0211] A first optical component may surround only a part
of a second optical component in the front surface 10a of the
display body 10.
[0212] The display body described above does not have to
be a display body that limits counterfeiting of a verification
subject by allowing authentication of the verification subject,
and may be a display body that is attached to an object for
decoration and a display body that is appreciated as an art
piece on its own.
57
We claim:
1. A display body comprising:
a first surface including a first optical surface and a
second optical surface, wherein first light is incident on the
first surface from an observation side;
a second surface located opposite to the observation
side with respect to the first surface, wherein second light
is incident on the second surface from a side opposite to the
observation side with respect to the second surface;
a first optical component including the first optical
surface, wherein the first optical component forms first
information, which is displayed on the observation side, from
the first light received on the first optical surface; and
a second optical component including the second optical
surface, wherein the second optical component receives the
second light transmitted through the second surface, forms
second information, which is displayed on the observation side,
from the second light, and emits the second information from
the second optical surface, wherein
the second optical component is an uneven structure,
the uneven structure includes
an uneven structure portion including a dielectric
that transmits light, and
a metal layer covering at least a part of the
uneven structure portion,
one of an interface between the uneven structure portion
and the metal layer and a surface of the metal layer that is
opposite to the interface is the second optical surface, and
the uneven structure includes a plasmon structure that
receives the second light on the interface and excites surface
plasmons on the metal layer so that the second optical surface
emits transmitted light that forms the second information and
differs from the second light in color.
58
2. The display body according to claim 1, wherein the
first optical component surrounds the second optical component
in the first surface, and
the first surface is described by Expression (1):
0.01 ≤ S2/S1 ≤ 0.4 (Expression 1)
where S1 represents an area of the first surface that is
occupied by the first optical component, and S2 represents an
area of the first surface that is occupied by the second
optical component.
3. The display body according to claim 1, whereinthe
second optical component is configured to receive the first
light on the second optical surface and emit light that mimics
the first information.
4. The display body according to any one of claims 1
to 3, wherein
the second optical component includes
a first plasmon structure that emits the
transmitted light in a first color, and
a second plasmon structure that emits the
transmitted light in a second color that differs from the
first color.
5. The display body according to any one of claims 1
to 4, wherein
the uneven structure portion includes a plate portion,
which has a base surface serving as one surface, and a
plurality of protrusions, which projects from the base surface,
and
the base surface is substantially parallel with an
imaginary plane including top surfaces of the protrusions.
6. The display body according to claim 5, wherein a
distance between the base surface and the imaginary plane of
59
the uneven structure portion is between 30 nm and 500 nm,
inclusive.
7. The display body according to any one of claims 1
to 6, wherein
the metal layer has a thickness of between 20 nm and 100
nm, inclusive, and
the metal layer includes a material of which the real
part of the complex dielectric constant is negative ina
visible light range.
8. The display body according to claim 5, wherein
theprotrusions are arranged in one of a triangular
lattice pattern, a square lattice pattern, and a hexagonal
lattice pattern on the base surface, and
theprotrusions arranged on the base surface have a pitch
of between 100 nm and 600 nm, inclusive.
9. The display body according to claim 5, wherein the
protrusions are arranged irregularly on the base surface.
10. The display body according to claim 5, wherein
the second optical component includes a first display
element and a second display element,
the first display element and the second display element
each include a part of the plate portion and at least one of
the protrusions, and
the first display element differs from the second
display element in at least one of a pitch of the protrusions
arranged on the base surface, a distance between the base
surface and the imaginary plane, an arrangement state of the
protrusions on the base surface, a thickness of the metal
layer, and a material forming the metal layer.
11. The display body according to claim 5, wherein
60
the uneven structure is a second uneven structure,
the base surface is a second base surface,
theplate portion is a second plate portion,
theprotrusions are second protrusions,
the first optical component is a first uneven structure,
and
the first uneven structure includes:
a first plate portion including a first base
surface serving as one surface; and
a plurality of first protrusions projecting from
the first base surface.
12. The display body according to claim 11, whereinthe
first protrusions arranged on the first base surface have an
average pitch of between 200 nm and 2000 nm, inclusive.
13. The display body according to claim 11 or 12,
wherein
surfaces of the first protrusions and a section of the
first base surface that is free of the first protrusions form
the first optical surface,
the first optical surface is a reflection surface that
reflects the first light to the observation side, and
the first protrusions are arranged irregularly on the
first base surface.
14. The display body according to any one of claims 1
to 13, further comprisinga print layer located on at least one
of a side of the first surface on which the first light is
incident and a side of the second surface on which the second
light is incident, wherein the print layer does not transmit
at least part of visible light such that the print layer forms
third information on the observation side,
wherein, in a plan view of the first surface, the print
layer overlaps with at least one of a part of the first
61
optical component and a part of the second optical component.
15. A method for observing a display body, wherein
the display body includes:
a first surface including a first optical surface
and a second optical surface, wherein first light is incident
on the first surface from an observation side;
a second surface located opposite to the
observation side with respect to the first surface, wherein
second light is incident on the second surface from a side
opposite to the observation side with respect to the second
surface;
a first optical component including the first
optical surface, wherein the first optical component forms
first information, which is displayed on the observation side,
from the first light received on the first optical surface;
and
a second optical component including the second
optical surface, wherein the second optical component receives
the second light transmitted through the second surface, forms
second information, which is displayed on the observation side,
from the second light, and emits the second information from
the second optical surface,
the second optical component is an uneven structure,
the uneven structure includes
an uneven structure portion including a dielectric
that transmits light, and
a metal layer covering at least a part of the
uneven structure portion,
one of an interface between the uneven structure portion
and the metal layer and a surface of the metal layer that is
opposite to the interface is the second optical surface, and
the uneven structure includes a plasmon structure that
receives the second light on the interface and excites surface
plasmons on the metal layer so that the second optical surface
62
emits transmitted light that forms the second information and
differs from the second light in color,
the method comprising:
causing the first light to be incident on the first
surface;
observing the first information formed by the first
optical component from the first light incident on the first
surface;
causing the second light to be incident on the second
surface; and
observing the second information formed by the second
optical component from the second light incident on the second
surface.
16. The method for observing a display body according
to claim 15, wherein
the first optical component surrounds the second optical
component in the first surface,
the first surface is described as 0.01 S2/S1 0.4,
where S1 represents an area of the first surface that is
occupied by the first optical component, and S2 represents an
area of the first surface that is occupied by the second
optical component, and
the observing the second information includes observing
the second information with the display body magnified.