HELMET SYSTEM HAVING ADJUSTABLE LIGHT TRANSMISSION
FIELD OF THE DISCLOSED TECHNIQUE
The disclosed technique relates to head mounted display {HMD]
systems, in general, and to Ώ systems, which visor has an adjustable
light transmission, n particular.
BACKGROUND OF THE DISCLOSED TECHNIQUE
The visor of a helmet may be a tinted visor (i.e.. a shaded visor),
having lower light transmission than dear visor. Such tinted visor
reduces the brightness o the ambient light arriving a the user's eye, in
order to provide the user with a better view n bright conditions. The
degree of transmission or alternatively the transmission of certain
wavelengths ma vary fro visor t visor, Furthermore, th transmission
of the visor ma be adjustable an controllable, automatically or manually.
Additionally, the visor can include several areas, each having a respective
light transmission. Moreover, on or more areas o the visor can have
adjustable and controllable light transmission.
US Patent No. 8,487,23382 issued to Baudou e aL. entitled
"Vision Equipme Comprising an Optical Strip with a Controlled
Coefficient of Light Transmission" s directed t a vision system having a
controlled light transmission optical strip. This publication describes a
vision equipment system of a helmet of a pilot including a visor (40 , an
image projection device (45) an a plurality of UV LEDs (41 , 42, 43 and
44). Visor 4 includes several portions of adjustable light transmission
(48, 47 and 48). The adiustabie light transmission portions are activated
by the UV LEDs according t measured luminosity levels. The image
proiection device of this publication projects the image onto the inner side
o the visor such that the projected image does not pass v a the visor, but
is reflected therefrom toward the eye of the user.
US patent No 5.640,71 1 issued to Lefort et a entitled
"Head-mounted visor with variable transmission", is directed to a
head-mounted visor having at least two zones with different values of
absorption of light The visor inciudes two f r tionai!y different zones. One
zone has a higher absorption, and corresponds to the wearer's visual field
of the outside scene. Another has a lower absorption, and corresponds to
the view of the dashboard instruments.
US patent No. 7,893,890 issued to Ke iy et a . and entitled
"Electrically dimmable combiner optics for head-up display", is directed to
a system for providing head-up displays with variable light transmission.
The system includes a combiner and a projector, wherein the projector
projects an image onto the combiner. Alternatively, the combiner may
have an internally integrated display module. The system also inciudes a
light sensor, which detects the light intensi outside the cockpit portion.
The light senso transfers this information to an operative!y coupled
combiner control device coupled with the combiner. The control device
adjusts the transmission of the combiner after receiving information
relating to ambient the light intensity. Further alternatively, the operator
may manually control the transmission of the combiner.
The combiner may include one or more segments to provide varying
levels of transmission of light For example, the combiner may be divided
vertically, horizontally, or both, to create segments of the combiner.
Additionally, the combiner may be wearable, fo example in the form of a
visor attached to a helmet.
SUMMARY OF THE PRESENT DISCLOSED TECHNIQUE
It is an object of the disclosed technique to provide a novel
method a d system for displaying an image on a Helmet Mounted Display
(HMD) system while adjusting the Sight transmission properties of the visor
of the HMD system. n accordance with an embodiment of the disclosed
technique, there is thus provided an HMD system including a visor, a
luminosity sensor, and a UV activation radiation source. The visor s
mounted on a head of a user. The visor includes an adjustable light
transmission layer activated by activation radiation including at least a
visible activation waveband and an Ultra Violet (UV) activation waveband.
The visor defines a L ne Of sight (LOS) projecting from a point on the
visor, and defines a Field Of View (FOV) projecting from at least a section
of the visor that surrounds that point. The luminosity sensor is configured
to detect luminosity within the FOV. The UV activation radiation source is
configured to selectively irradiate activation UV light according to
luminosity detected by the luminosity sensor. The HMD system is located
in a UV-attenuated environment such that the adjustable ight
transmission layer is activated by activation ambient light in the visible
activation waveband, and can further be activated by activation U Iight
emitted from the UV activation radiation source.
In accordance with another embodiment of the disclosed
technique, there is thus provided a method for operating an HMD system.
The method includes the steps of determining a FOV of the HMD system,
measuring luminosity within the FOV, determining a desired light
transmission level, a d irradiating UV activation radiation on the visor of
the HMD. The luminosity is measured within the FOV of the visor of the
HMD by employing a luminosity sensor. The irradiated UV activation
radiation induces the desired Iight transmission level of the visor.
BRIEF DESCRIPTION OF THE DRAWINGS
The disclosed technique will be understood and appreciated
more fully from the following detailed description taken in conjunction ith
the drawings i which:
Figure 1 is a schematic illustration of block diagram of an
adjustable light transmission HMD system, constructed and operative in
accord cewith a embodiment of th disclosed technique;
Figure 2 s a schematic illustration of an adjustable ig ht
transmission system, depicted from a sid view, constructed and
operative n accordance with another embodiment of th disclosed
technique;
Figure 3 a schematic Illustration of an adjustable ight
transmission HMD system, depicted from a sid view, constructed and
operative in accordance with a furthe embodiment of the disclosed
technique
Figure 4 i a schematic illustration of an adjustable light
transmission D system, constructed and operative in accordance with
yet another embodiment of th disclosed technique;
Figure is a schematic illustration of method for controlling
the light transmission of visor o HMD system, operative in accordance
with yet further embodiment of the disclosed technique; and
Figure 6 is a schematic illustration of a method for controlling
the light transmission of a visor of a HMD system, operative in accordance
with yet another embodiment of the disclosed technique.
DETAILED DESCRIPTION OF TH EMBODIMENTS
The disclosed technique overcomes the disadvantages of the
prior art by providing a HMD system with a visor including a layer of
adjustable an controllable light transmission. The adjustable light
transmission layer (also referred to herein simply as the adjustable layer)
of the visor o the disclosed technique can be activated at least by light
wavelengths within the U spect r .
The HMD system of th disclosed technique can be employed,
for example, by pilots In aircr s . n many a r rafis, the windows- the
cockpit include a Ultra Violet (UV) blocking layer, for blocking, or at least
attenuating, UV portions of the ambient ig ht entering the cockpit. Thus,
the cockpit can b considered as a UV-free environment or at least a
UV-attenuated environment). The U wavelengths employed for
controlling the light transmission of the adjustable layer are within the
attenuated UV spectrum. Additionally, the adjustable iayer may further beactivated
by un a nuated l wavelengths (e.g., visible light
wavelengths) included in ambient light t is noted that the HM system
can be employed in other UV attenuated environmefits besides aircraft
cockpits.
ft is noted that the visor of the HMD system is associated with a
Field of View (FOV) of the HMD, projecting from an area of th visor (i.e.,
the FOV area). The visor is further associated with a Line of Site (LOS) of
the projecting from a respective point of the visor, located within the
FO area of the visor. Thus, one ca determine the FOV of the HMD by
determining the LOS of the HMD, and vice versa. Therefore, the terms
LOS and FOV may be interchangeably used throughout the application.
Generally, the LOS i determined by a respective sensor (e.g. an
orientation sensor), and the FOV derived therefrom.
n accordance with an embodiment of the disclosed technique,
the adjustable transmission HMD system furthe includes a UV radiation
-ssource,
a controller a LOS sensor, a a luminosity sensor. The
controller is coupled with each of the UV radiation source, the LOS sensor
and the luminosity sensor, for controlling and coordinating the operation
thereof. The LOS sensor determines the LOS of the HMD The
luminosity sensor determines the luminosity levels within the FOV of the
D The controller controls the UV radiation source for activating the
adjustable layer according to th determined lu i osity within the FOV of
th HMD In case the luminosity sensor and the UV radiation source are
mounted on the HMD, and ar aligned with the FOV of the HMD, the LOS
sensor can be omitted from the adjustable transmission HMD system.
In accordance with another embodiment of the disclosed
technique, the adjustable layer is controlled by tw activation light
wavebands (dual activation). In particular, one of the activation
wavebands is visible, and the other activation waveband is within the U
spectrum, As mentioned above, visible light can penetrate the cockpit,
while UV light cannot (or a least is attenuated when penetrating th
cockpit). Thus, ambient light can serve as th visible light activation
source. n this manner, the light transmission of the adjustable layer of
the visor i automatically and uncontrollably adjusted according to the
ambient light impinging on the visor. That s, the adjustable layer s
automatically activated, and the light transmission thereof s adjusted, by
the ambient light without intervention of the controller component or the
user. A itionally in case o a special need, the adjustable layer can
furt he be activated by the adjustable transmission HMD system via the
U radiation source. For instance, In case the user provides appropriate
instructions via an input interface.
The dual activation wavebands ca be, for example, two
adjacent wavebands (i.e., adjacent along the electromagnetic radiation
spectrum) lying on either sid of the UV/ is e ligh border. That is, the
activation wavebands are a deep blue waveband i.e., located at the end
of the visible spectrum close to the UV spectrum}, and a near UV
waveband located at the end of the UV spectrum close to the visible
spectrum. Deep blue ambient light can penetrate the cockpit and serve as
the visible Sight activation source. Near UV ambient light cannot penetrate
the cockpit {or at least is attenuated when penetrating the cockpit), and
the near UV radiation source is employed for activating the adjustabie
layer in case of a special need. Alternatively, any two other wavebands,
one visible and one UV can be employed for activation of the adjustable
layer. Further alternatively, the visor includes two adjustable layers, one
activated by visible radiation and th other b UV radiation.
Reference is now made to Figure 1, which s a schematic
illustration of a block diagram of an adjustable light transmission HMD
system, generally referenced 100, constructed and operative in
accordance with an embodiment of the disclosed technique. Adjustable
light transmission HMD system 100 (i.e., HMD system 100) includes a
visor 102 including an adjustable light transmission laye (not shown), an
Ultra Violet (UV) radiation source 104, a controller 108, a Line of Site
(LOS) sensor 108, and a luminosity sensor 110. UV radiation source is
optically coupled with visor 102. That is, UV radiation source can project
UV radiation onto at least a portion of visor 2 for activating the
adjustable layer thereof. Controller 106 s coupled with UV radiation
source 4 , LOS sensor 108 an with luminosity sensor 1 .
System 100 is mounted on the head of a user (i.e., a head
mounted system), for example, by a head strip, a helmet or any other
head mount. Alternatively only some of the components of system 1 0
are mounted o the head of the user, while other components are
positioned in the surrounding vicinity. For example, the visor, the radiation
source and the luminosity sensor are mounted on a helmet of a pilot, while
the processor is positioned in a cockpit of an airplane.
In accordance with an embodiment of the disclosed technique,
HMD system 100 is located within a cockpit of an aircraft (both not
shown). The windows of the cockpit block (or at least attenuate) UV
radiation. Visor 10.2 includes an adjustable light transmission layer that
can be controlled via electromagnetic radiation (e.g., photochrome layer
activated by light). For example, visor 102 can be coated with a
photochromic layer, can be coupled to a photochromic layer or can be
made entirely from a photochromic material Other examples of a
photochromic visor are visors at which the photochromic material is
embedded into or otherwise integrated into. For example, the visor can
include liquid crystal bubbles containing photochromic particles. The
adjustable layer of visor 102 is activated by at least one activation
waveband of light, including at least some wavelengths lying in the UV
portion of the spectrum (i.e., UV light). Additionally, the activation
wavebands of the adjustable layer can inciude visible wavelengths.
it is noted that the adjustable layer of visor 102 can be made to
occupy only a portion of v sor 2 (e.g., a portion or a patch of visor 102).
In this manner, the light transmission of some portions of the visor 2 is
constant and cannot be adjusted, while the light transmission of the patch
including the adjustable layer, can be adjusted and controlled. Moreover,
visor 102 can include several patches, each including a respective
adjustable layer, such that the light transmission of different portions of
visor of 2 can be controlled separately. Each such adjustable patch can
be activated by the same wavebands, or by unique wavebands. In such
cases, HMD system 1 0 can include several UV radiation sources 1 4 for
activating each of the adjustable patches.
UV radiation source 104 can be an light source producing UV
light (i.e., UV radiation). For example, UV radiation source 104 is a UV
LED 104, or a plurality of UV LEDs 104. Controller 6 can be any device
that can coordinate the operation of the sensors of HMD system 100,
receive data from the sensors, and that can accordingly control the
operation of UV radiation source 4 , For example, controller 10 is a
processing device or a network of processing devices,
LOS sensor can be any device that can determine the LOS
of the HMD, or that can acquire readings that would allow controiier 106 to
determine the LOS of the HMD, LOS sensor 108 can he mechanical
sensor, optical sensor, electromagnetic sensor, ultrasonic sensor, or any
other LOS sensor, o orientation sensor, known in th art. Luminosity
sensor 110 can be any device that ca determine luminosity levels, or
light intensity, a a respective FOV. Luminosity sensor 110 measures th
luminosity at a respective ligh spectrum. In accordance with an
embodiment of the disclosed technique, the luminosity sensor spectrum
includes at least the visible activaiion wavebands of th adjustable layer of
visor 102. Alternatively; the luminosity detection spectrum can include
any w av ebands, whether incl uding the activation wavebands or not.
During operation of HMD system 100, LOS sensor 8 acquires
readings respective of the LOS of the HMD on which v iso 2 is installed.
LOS sensor 108 either determines the LOS ot the HMD and provides the
LOS to controller 106, or provides the acquired readings to controller 106
that determines the LOS of the HMD by itself. Controller 106 determines
the FOV of the HMD according to the LOS of the HMD. Controller 106
instructs luminosity sensor to measure the luminosity within the FOV
o the HMD Luminosity sensor 1 measures th luminosity and
provides the readings back to controller 1 6.
n accordance with one embodiment of the disclosed technique,
the adjustable layer of visor 2 is activated solely y U radiation.
Controiier 6 determines a desired light transmission level of th
adjustable layer (i.e.. of visor 2} according to the measured luminosity
level. Accordingly, controller 106 operates UV radiation source 104 to
project UV radiation onto visor 102 for inducing the desired ig ht
transmission levels in visor 02 . A the cockpit can b considered as a
UV-free environment, the adjustable layer is only activated when UV
radiation source irradiates visor 2,
In accordance w th another embodiment of the disclosed
technique, the adjustable layer i activated by two activation wavebands,
a visible waveband a d UV waveband. For example, th adjustable
layer is activated by a waveband located on the border between the
visible spectrum an th UV spectrum, which includes both visible
wavelengths ., dee blue wavelengths), and UV wavelengths (near
UV wavelengths). Thereby, the adjustable layer is affected by the deep
blue wavelengths of th ambient light penetrating the cockpit. Th
adjustable layer is adapted to reach a predetermined desired level of light
transmission by the ambient light deep blue wavelengths. In this manner,
th adjustable layer automatically and uncontrollably activated without
interference of controller 16 or of the user.
Additionally, controller 108 ca complement (or replace) the
activation o the adjustable layer by ambient light wit activation by UV
light. Controller 1 operates UV radiation source 4 to activate th
adjustable layer when activation by ambient light is insufficient. For
example, in case the pilot Is not comfortable with induced light
transmission levels, the pilot can control the Sight transmission via
controller and UV radiation source 104 (i.e., via a user interfac
coupled with controller 106). Alternatively, controller 106 can further
activate the adjustable layer according to other conditions, such as data
the time of da (day/night), the weather (e.g., temperature, precipitation,
cloudiness), background of outside scene (e.g., a bright desert sand or a
dark forest), and the like. Controller 8 receives data respective of such
conditions from externa! systems, such as the navigation systems of the
aircraft, meteorological systems of th aircraft and other sensory systems
of the aircraft.
Controller 108 monitors the luminosity levels within the HMD
FOV (via LOS sensor 0 and luminosity sensor 1 0) Controller can
also monitor the light transmission level of the adjustable !ayer. For
example, controller 106 can determine th light transmission b
calculating it according to the measured luminosity levels. Alternatively,
HMD system 100 can include an additional luminosity sensor located
behind the adjustable layer, and controller 108 can calculate the light
transmission b comparing the readings of the two sensors. In case
controller 106 determines tha th transmission leve of th adjustable
layer does not correspond to the desired level, controller 06 operates UV
radiation source to further activate the ad ustabl layer t Induce the
desired fight transmission level.
I noted that th adjustable layer can activated by other
pairs of visible and UV activation wavebands. Alternatively, visor 1 2
includes tw overlapping adjustable light transmission layers, one
activated by a visible waveband, and th othe by a UV waveband.
Thereby, the light transmission of visor 02 can be automatically an
uncontrollably adjusted b ambien light penetrating the cockpit, and can
be further activated by the UV radiation source according to instructions of
controller 8 or of the user.
Reference is now made to Figure 2 which is a schematic
illustration of an adjustable light transmission HMD system, generally
referenced 200, constructed and operative in accordance with another
embodiment of the disclosed technique. HMD system 200 includes
visor 202, a UV radiation source 204, a controller 20 a luminosity sensor
210, a helmet 21 and a support arm 214. Each of visor 202, UV
radiation source 204, controller 206 and luminosity sensor 210 is
substantially similar is construction and operation to visor 102, UV
radiation source 104, controller 1 6 and luminosity sensor 110, of Figure
.
The components of H system 200 are mounted on a helmet
2 2, via support arm 214 or via another support mechanism 2 14 . U
radiation source 204 and luminosity sensor 21 are mechanically aligned
with a LOS 218 and with a FOV 220 of helmet 212 by being connected to
helmet 212 via support ar 214. Therefore, LOS sensor can be omitted
from HMD system 2.00. Alternatively, in case a least one o UV radiation
source 204 and luminosity sensor 2 1 is not mounted on helmet 2 1 , and
aligned therewith, HMD system 20 further includes a LOS sensor for
determining LOS 2 , and thereby, FOV 22 of helmet 212,
Controller 20 determines the desired luminosity !evei for visor
202. Accordingly, controller 20 operates UV radiation source 204 to
induce the desired luminosity level in the adjustable layer (not shown of
visor 202. I s noted that the adjustable layer ca either e activated o ly
by UV radiation, or can be activated by UV radiation as well as by visible
radiation. In the latter case (i.e., dual activation), the adjustable layer i
automatically an uncontrollably activated by ambient light - without
intervention- of controller 20 or of th user. In case of special need,
controller 206 operates UV radiation source 204 to complement the
activation of the adjustable layer by the ambient light to induce a desired
light transmission In visor 202.
HMD system 200 can further include an image source mounted
on arm 214. The image source projects a image towards the eyes of the
pilot. The projected mage s overlaid on the outside scene as seen
through the visor.
in the example detailed herein above with reference to Figure 2,
the HMD system was mounted on a helmet of a pilot. Alternatively, HMD
system can he any head mounted system and not necessarily a helmet
mounted system. For instance, HMD system can be mounted o a strap,
or a glasses-like frame.
Additionally in the example detailed herein above with reference
to Figure 2 , the HMD system was located within a cockpit of an aircraft.
Alternatively, the HMD system oan e employed other environments.
For example, the HMD system can be employed in other vehicles having
UV attenuating windows, such as land- or marin vehicles. The HMD
system ca foe employed in stationary environments such in-door
simulators withi buildings (or rooms) having UV attenuating windows.
Generally, HMO system ca be employed within any U attenuated
environment, and can fo mounted on the head of the user by any
; mounting means.
Further additionally, n the example detailed herein above with
reference to Figure 2 the HM syste has front projection
configuration, in which the UV radiatio source and the image source are
mounted outside the visor and are project light onto the externa} side of
the visor, Alternatively, HMD system ca b bae i projection system
which at least o e of the UV radiation source and the mage source
positioned on the inner side f the visor, and irradiate the inner side of the
visor.
is noted that the UV radiation source and the image source
can h positioned on opposite sides of the visor. For example, the image
source projects the image on the exterior side of the visor and the UV
radiation source irradiates the interior side of the visor. n th s manner, the
user is not irradiated with the UV activation radiation (i.e., as the visor i
not reflecting visor).
Reference is now made to Figure 3 , which is a schematic
illustration o an adjustable light transmission HMD system, generally
referenced 300, constructed an operative in accordance with another
embodiment of the disclosed technique. HMD system 300 includes a
visor 302, a UV radiation sourc 304, a luminosity sensor 3 10, a head
strap 3 2 and an mage source 314 HMD system further includes a
controller (not shown) coupled with th other components of system 300
for controlling and coordinating their operation; Visor 302, UV source 304
and luminosity sensor 3 0 are mounted on hea strap 312 Alternatively,
head strap 3 ca e replaced by any other head mount, such as an
eyeglasses frame, a helmet, and the like.
Visor 302 cludes (or is coupled with) a adjustable light
transmission layer. Visor 30 or at least a portion thereof) s a sem
reflective visor that reflects a portion of the light irradiated onto and admits
the other portion f the Sight. Thereby, visor 30 operates as an image
combiner . combining an image projected onto t interior surface by image
source 31 and th outside scene.
Image source 3 generates and projects an image onto visor
302. The generated i age is, for example, a data mage detailing data for
the user. For instance, the data image can detail flight parameters, and
other indicative of the status of various systems of the aircrafts, or
data detected by the sensory systems of the aircraft. At least a portion of
the image i reflected by visor 302 toward the eye of the user (e.g., visor
302 back reflects half of the light intensity of the image). Additionally,
visor 302 admits a portion o the outside scen (e g,, half of the light
intensity of the outside scene). Thus, the user receives the outside scene
overlaid by the image generated by image source 3 14
UV radiation source 304 can adjust the light transmission of
visor 302 by irradiating it with UV radiation. n accordance with an
embodiment of the disclosed technique, the light of the outside scene also
activates the adjustable layer of the visor (i.e., dual activation). n this
case, the outside light automatically adjusts the light transmission of the
adjaustab!e layer, and in case that the controller (or the user) determines
that further activation is required, UV radiation source is employed.
Luminosity sensor 3 1 determines the light luminosity levels of
the outside scen mage impinging on visor 302, and provides the
measurements to he controller. The controller employs the measured
luminosity levels for determining whether activation of the adjustable layer
by UV source 31 s required. The controller can further receive other
data for determining the desired Sight transmission level of the adjustable
layer of the visor, such as the time of da y. the weather conditions, the
background of the outside scene, and the like.
The example detailed herein above w th reference to Figure 2
relates t a helmet. It is noted however, that th disclosed technique ca
implemented by an HMD system, as exemplified in Figure 3.
Furthermore, the example set forth with reference to Figure 2, relates to
a external projection system, and that of Figure relates to an interna!
projection syste However, the disclosed technique can be implemented
in any of the two configurations (i.e., internal and external projections).
Alternatively, the disclosed technique can be implemented without an
image source component at all ( e., the user receives only the outside
scene image without any image overlaid thereon).
Reference is no made to Figure 4 which is a schematic
illustration of m adjustable light transmission H D system, generally
referenced 400, constructed and operative in accordance with a further
embodiment o the disclosed technique HMD system 400 includes a
visor 402 of a HMD 412, a plurality o UV radiation sources 404, a
controller 408, a LOS sensor H u it 4 A, LOS sensor cockpit unit
408B, and a plurality of luminosity sensors 410. HMD system 400 is
installed within a cockpit having UV blocking windows ,
Visor 402 includes a adjustable light transmission layer (not
shown) which lig t transmission can be controlled by specific activation
wavebands of electromagnetic radiation. UV radiation sources 404
produce UV radiation including activating wavelengths that activate the
adjustable laye of visor 402. Controller 406 is coupled with the othe
components of HMD system 400 for controlling and coordinating the
operation thereof. LOS HMD unit 408A is positioned on HMD 412 and is
wirelessly connected to LOS cockpit unit 4G8B, fo determining a LOS 4 1
of HMD 412, For example, the LOS sensor s an optical sensor,
electromagnetic sensor, ultrasonic sensor, or any other sensor for
determining LOS 4 1 of HMD 412, or the orientation of HMD 412.
Luminosity sensors 410 measure luminosity levels within a respective
FOV.
¥ radiation source are spread across the cockpit of the aircraft
(i.e., across the windows of he cockpit). Each of UV radiation sources
4 4 is paired with a respective one of Iuminosity sensors 4 , such that
bot sit on the same axis facing opposite directions. In particular, the
luminosity senso of each pair faces the exterior environment surrounding
the cockpit, and th radiation source faces the interior of the cockpit n
this manner, the UV radiation source of each pair can irradiate activation
Sight at a intensity determined according to the measured ambient light
(i.e., measured by th respective luminosity sensor). Tha is, the UV
radiation sources ca either be controlled b controller 406, or can be
operated automatically according to the iuminosity measured by the
respective sensor, without intervention of controller 408,
Controlier 406 is coupled with UV radiation sources 404, LOS
sensor units 4 08A and 408B (or at least with one of the LOS sensor units),
and with luminosity sensors 410. Controller 40 receives LOS 418 of
HMD 4 12 from LOS sensor units 408 Ά and 408B. Controller 406
determines according t LO 418 a FOV 420 of HMO 4 , Controller 406
operates luminosity sensors 4 1 located within FOV 420 (marked in
Figure 4 b diagonal lines for convenience of the viewer), fo determining
the luminosity of ambient light within FOV 420. Accordingly controller 408
determines a desired light transmission leve for visor 402 (i.e . for the
adjustable layer of visor 402)
n accordance with one embodiment of the disclosed technique,
th adjustable layer s activated onl y UV radiation. Controller 40
Qperaies UV radiatiori sources 404 located within FOV 420 (marked
Figure 4 by diagonal lines for convenience of the viewer), for irradiating
visor 402, for adjusting the light transmission level of visor 402
Alternatively, controller 40 determines FO 420, and operates those of
luminosity sensors 410 that are within FOV 420. Th UV radiation
sources 404 within FOV 420 emit UV light according to the luminosity
measured by the paired one of luminosity sensors 4 1 Further
alternatively, HMD syste 400 does not include controller and a LOS
sensor, instead, each of UV radiation sources 404 emits UV light
according to the luminosity measured by the respective luminosity sensor,
regardless of the LOS of the HMD.
In accordance with anothe embodiment of the disclosed
technique ., the adjustable laye can be dually activated by a visible
waveband, and by a UV waveband. The visible activating wavelengths,
which are part of the ambient light, penetrate cockpit windows 418 and
automatically an uncontrollably activate th adjustable layer. The
adjustable layer of visor 402 s adapted to reach a predetermined desired
level of light transmission via activation by ambient light. Controller 400
can further activate the adjustable layer (e.g., according to respective
nput o a pilo wearing HlvlD 412 via an input interface) by operating UV
radiation sources 404.
Reference is now made to Figure 5, whic is a schematic
illustration of a method for controlling the ig ht transmission of a visor of a
Hlv D system, operative in accordance with yet another embodiment of the
disclosed technique in procedure 500, a Field of View (FOV) of a HlvlD is
determined. The FOV can he determined according to a na of Site
(LOS) of the HMD, which i determined by a LOS sensor. For example,
the LOS sensor can be an optical sensor, an electromagnetic sensor or an
ultrasonic sensor for determining the orientation of the HMD. it is noted
that in case the components o a Hfv D system are installed on the HMD,
and are mechanically aligned with the FOV of th HMD, procedure 500
may he omitted from the method. With reference to Figure LOS sensor
108 determines the LOS of th HMD. Accordingly, controller 10
determines the FOV of the H .
procedure 502, the luminosity levels within the FOV of the
HMD are measured. Th luminosity measured by luminosity sensor
or sensors. Th measured luminosity ca e limited to selected
wavebands (e.g., measuring only visible ig ht luminosity, or measuring
some wavebands within th UV and spectru a wel as the
luminosity o visible light). With reference to Figure controller 10
operates luminosity sensor 110 for determining th luminosity within the
FOV f the--HMD.
n procedure 5 4 a desired light transmission level of a visor o
the HMD i determined. The desired ligh transmission level s
determined according to the measured luminosity within the FOV of the
HMD, for exa ple to prevent blinding of the pilot f y bright ambient light.
It is noted that different pilots might have different desired light
transmission levels, an thud the HMD system ca he calibrated for each
pilot. Additionally, the desired light transmission levels can be affected y
other conditions, such as weather conditions clear or cloudy sky, raining
or snowing conditions}, the day/night cycle and th angle of th sun, the
background o the outside scene (e.g., a white building, a b gh desert
sand or a dark forest), and the like. With reference to Figure 1, controller
6 determines a desired light transmission level of visor 2 according to
the measured luminosity within the FOV of the HMD.
In procedure 506, the visor of the HMD i Irradiated with UV
radiation for inducing the desired light transmission level. The viso of the
HMD Includes a adjustable ig ht transmission layer, which light
transmission properties can be adjusted and controlled. For example, the
visor includes a phofochromic layer activated b UV light it Is noted that
only a selected area (or areas) of the visor includes the adjustable layer
(i.e. , an adjustable patch or patches). The adjustable layer (or patch) is
irradiated with activating radiation to induce the desired light transmission
levels the visor. Alternatively, the adjustable layer covers the entire
surface of the visor. With reference t Figure controller 6 operates
UV rad a on source 104 to activate the adjustable layer of visor 102,
thereby controlling the light transmission properties of visor 102. It i
noted that the HMD system is installed within cockpit which usually
includes UV blocking windows, such that the interior of the cockpit ca b
considered as a UV-free environment.
Reference is now made t Figure 6, which is a schematic
illustration of a method for controlling th light transmission of a visor of
HM system, operative in accordance with ye a further embodiment of
the disclosed technique. Procedures 600, 602 and 604 of the method are
substantially similar to procedure 500, 5 2 and 504, of the method Figure
5 , respectively. However, the adjustable layer of the visor of a HMD
system controlled according to the method of Figure 5 is activated solely
by UV radiation, while the adjustable layer of th visor of a H D system
controlled according t the method of Figure 6 can be dually activated b
both a visible waveband and a U waveband. For example, the
photochromic layer is activated by a waveband located on the border
between th visible spectrum and the UV spectrum, such that a portion of
the activating wavelengths are visible (e.g., deep blue wavelengths) and a
portion of the activating wavelengths are UV (e.g. , near-UV wavelengths).
In this manner, the visible activating wavelengths that are a part of the
ambient light and that penetrate the cockpit windows irradiate the visor,
and activate the adjustable layer. The adjustable layer is adapted to
reach a predetermined level of light transmission in response to the visible
activating ambient light Thus the light transmission of the visor is
automatically and uncontrollably activated without intervention of the
controller of the HMD system, or of the pilot-
In procedure 608, current light transmission level of the visor of
the HMD determined. Th current light transmission level ca be
calculated according to the measured luminosity levels within the FOV of
the HMD as measured n procedure 602. That is, by knowing the intensity
of the activating visible light, and knowing th operational characteristics
of th adjustable layer, the induced light transmission levels can be
calculated. Alternatively, the current light transmission ca be measured
by employing a luminosity sensor positioned behin the visor, and
measuring the luminosity levels thai penetrate th visor. The luminosity
levels i front of the visor and behind the visor are compared and the figh
transmission ca thus h determined. Additionally, the desired light
transmission ieveis can be affected by other conditions, such a weather
conditions (clear or cloudy sky, raining or snowing conditions), the
day/night cycle and th angle of the sun, the background of the outside
scene (e.g., a whit building, bright desert sand o a dark forest), and
the like. With reference to Figure 1, controller 1 6 determines a desired
ig ht transmission level of visor according to the measured luminosity
within the FOV of the HMD.
In procedure 608, in case the current light transmission of the
visor of the HMD differs from the desired light transmission, the visor is
irradiated with UV radiation for inducing the desired light transmission
level, n this manner, th HMD system can complement the ambient light
activation of the adjustable layer o the visor with UV activation for
inducing the desired light transmission. It is noted that the desired light
transmission might differ from the predetermined desired light
transmission, employed for producing the adjustable layer, and therefore
the U activation Is required to complement th ambient light activation.
For example, case the pilot wants the further shade the visor, the pilot
provides respective input to the controller of the HMD system via a input
interface. The controller operates the UV radiation source for activating
the adjustable layer, thereby controlling the light transmission of th visor
Wit reference t Figure 1, controller 106 operates U radiation source
1 4 for controlling the light transmission of v sor 2
t will be appreciated by persons ski e in the ar that the
disclosed technique is not limited to what has been particularly shown and
described hereinabove. Rather the scope of the disclosed technique is
defined onl by the claims, which follow.
CLAIMS
A HMD system comprising:
a visor mounted on a head of a user, said visor including an
adjustable light transmission layer activated by activation radiation
including at least a visible activation waveband and an Ultra Violet
(UV) activation waveband, sai visor defining a Lin Of sigh (LOS)
projecting from point on said visor, said visor defining a Field Of
View (FOV) projecting from a least a section of said visor that
surrounds- sai point on said visor, said visor configured t admit an
outside scene image;
luminosity sensor configured to detect luminosity within said
FOV; and
a U activation radiation source configured to selectively
irradiate a leas a portion of said visor with activation UV light
included i sa d UV activation waveband according to luminosity
detected by said luminosity sensor, thereby activating said adjustable
ight transmission layer;
wherein, sai HMD system being located In a UV-attenuated
environment such that said adjustable light transmission ayer being
activated by activation ambient light in said visible activation
waveband, and can further be activated by activation UV light emitted
from said UV activation radiation source.
The HMD system of claim 1 further comprising a controller coupled
with said luminosity sensor and with said UV activation radiation
source, sai controller configured t receive luminosity detected bysaid
luminosity sensor, to determine a current light transmission level
according to luminosity detected by said luminosity sensor, to
determine desired light transmission level for said visor, and to
operate said UV activation radiation source for inducing said desired
light transmission level.
3 . The HMD system of claim 2 , further comprising a Line o Site (LOS)
sensor coupled with said controller, said LOS sensor configured to
determine sa d LOS defined by said visor, said controller configured
to determining said OV defined by said visor according to said LOS,
sa d controiier configured to operate said luminosity sensor to
measure luminosity in said FOV,
4. The HMD system of claim 2, wherein said controiier is configured to
determine said desired light transmission level of said visor at least
according to luminosity measured by said luminosity sensor.
5 . The system of claim 4 , wherein said controller is configured to
determine said desired Sight transmission level further according to at
least one of the list consisting of:
an input from a user;
the time of day;
the angle of the sun;
the weather conditions; and
a back o d of an outside scene.
8. The HMD system of claim 1, further comprising an image source
configured to generate a data image and to project said data image
onto said visor.
The HMD system of claim 6, wherein said image source is configured
to project said data image onto an interior side of said visor, and
wherein said visor being a semi-reflecting visor configured to reflect
sa d data image a d to admit said outside scene image.
8 . The HMD system of claim 8 , wherein said image sourc is configured
to project said data i age onto a exterior side f said visor, and
wherein said visor is configured to admit said data image and said
outside scene image.
9. The HMD system of claim 1 wherein said UV activation radiation
source s configured to irradiate an interior side o sai visor.
1 Th D system of claim 1, wherein said UV activation radiation
source i configured to irradiate an exterior side of said visor.
1 . The HMD system of claim , wherein said luminosity sensor consists
of a plurality of luminosity sensors an wherein sa UV radiation
activation source consists of a plurality of radiation sources, eac of
said radiation sources being associated with a respective one of said
luminosity sensors and is positioned on an axis of said respective
one of said luminosity sensors facing opposite directions,
wherein said plurality of luminosity sensors and said plurality of
radiation sources are spread across said UV attenuated environment,
and
wherein a selected one of plurality of radiation sources is
configured to irradiate activation radiation according to luminosity
detected by a respective one of said plurality of luminosity sensors
12, The HMD system of claim , further comprising a LOS sensor and a
controller, wherein said controller is configured t determine said
LOS of sai visor according to LOS readings of sa d LOS sensor, an
wherein sa controller is configured o operate selected ones of said
plurality of luminosity sensors and of sa d plurality of radiation
sources according to said LOS of said visor.
13. A method for operating an HMD system, comprising the following
procedures:
determining a FOV defined by a visor of sai HMD system;
measuring luminosity within said FOV by employing- luminosity
sensor;
determining a desired light transmission level of said visor; and
irradiating said visor with UV radiation for inducing said desired
ight transmission level
14. Th method of claim , further comprising the procedure of
determining current light transmission level o said visor according to
luminosity detected said luminosity sensor, and wherein said
procedure of irradiating said visor with UV radiation being performed
according to a difference between said current light transmission
level and said desired ig ht transmission level.