U.S. patent application number 12/401016 was filed with the patent office on 2009-09-17 for display apparatus, display method, goggle-type head-mounted display, and vehicle.
Invention is credited to Kakuya Yamamoto.
Application Number | 20090231687 12/401016 |
Document ID | / |
Family ID | 41062741 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090231687 |
Kind Code |
A1 |
Yamamoto; Kakuya |
September 17, 2009 |
DISPLAY APPARATUS, DISPLAY METHOD, GOGGLE-TYPE HEAD-MOUNTED
DISPLAY, AND VEHICLE
Abstract
A display apparatus includes a light source which emits a beam
including visible light forming an image and infrared rays, and a
transmissive deflection unit including a first surface facing the
eyes of a user and a second surface which is a rear surface of the
first surface. The transmissive deflection unit has transmissive
characteristics for transmitting the visible light from the second
surface side to the first surface side, deflection characteristics
for deflecting, toward the eyes of the user, the visible light
projected from the light source to the first surface side, and
infrared absorption characteristics for absorbing the infrared rays
projected from the light source to the first surface side.
Inventors: |
Yamamoto; Kakuya; (Hyogo,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK L.L.P.
1030 15th Street, N.W., Suite 400 East
Washington
DC
20005-1503
US
|
Family ID: |
41062741 |
Appl. No.: |
12/401016 |
Filed: |
March 10, 2009 |
Current U.S.
Class: |
359/359 ;
359/630 |
Current CPC
Class: |
G02B 27/017 20130101;
G02B 27/01 20130101; G02B 26/101 20130101 |
Class at
Publication: |
359/359 ;
359/630 |
International
Class: |
G02B 27/01 20060101
G02B027/01 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2008 |
JP |
2008-060654 |
Claims
1. A display apparatus which displays an image on a retina of a
user, said display apparatus comprising: a light source which emits
a beam including a visible light forming the image and an infrared
ray; and a transmissive deflection unit which includes a first
surface facing an eye of the user, and a second surface that is a
rear surface of said first surface, wherein said transmissive
deflection unit has: a transmissive characteristic for transmitting
the visible light from a second surface side to a first surface
side; a deflection characteristic for deflecting, toward the eye of
the user, the visible light projected from said light source to the
first surface side; and an infrared absorption characteristic for
absorbing the infrared ray projected from said light source to the
first surface side.
2. The display apparatus according to claim 1, further comprising:
a scan unit configured to perform two-dimensional scanning on said
first surface of said transmissive deflection unit, using the beam
emitted from said light source; and a control unit configured to
cause said light source to change an output intensity of the
infrared ray according to a position on said first surface onto
which the beam is projected for scanning by said scan unit.
3. The display apparatus according to claim 2, wherein said control
unit is configured to cause said light source to increase the
output intensity of the infrared ray as a position onto which the
beam is projected for scanning by said scan unit becomes closer to
a central part of said first surface.
4. The display apparatus according to claim 2, further comprising a
light detecting unit configured to detect a reflected light
intensity, on said transmissive deflection unit, of the beam
projected for scanning by said scan unit, wherein said control unit
is configured to cause said light source to change the output
intensity of the infrared ray according to a change of the
reflected light intensity detected by said light detecting
unit.
5. The display apparatus according to claim 2, further comprising a
line-of-sight detecting unit configured to detect a line-of-sight
of the user based on a reflected light, on the eye of the user, of
the visible beam deflected by said transmissive deflection unit,
wherein said control unit is configured to cause said light source
to increase the output intensity of the infrared ray as a position
onto which the beam is projected for scanning by said scan unit
becomes closer to a position where the line-of-sight of the user
detected by said line-of-sight detecting unit and said first
surface intersect with each other.
6. The display apparatus according to claim 1, wherein said
transmissive deflection unit includes: an infrared absorption layer
which is disposed on the first surface side, transmits the visible
light, and absorbs the infrared ray emitted from said light source;
a visible light deflection layer which is disposed on the second
surface side, transmits the visible light traveling from the second
surface side to the first surface side, and deflects, toward the
eye of the user, the visible light emitted from said light source;
and a heat insulation layer which is disposed between said infrared
absorption layer and said visible light deflection layer, transmits
the visible light, and blocks heat propagation between said
infrared absorption layer and said visible light deflection
layer.
7. The display apparatus according to claim 6, wherein said
infrared absorption layer has a different infrared absorptance
according to a position on said first surface.
8. The display apparatus according to claim 7, wherein said
infrared absorption layer has a higher infrared absorptance as a
position on said first surface becomes closer to the central part
of said first surface.
9. The display apparatus according to claim 2, wherein said scan
unit and said transmissive deflection unit are positioned such that
the infrared ray specularly reflected by said transmissive
deflection unit is projected onto a position that is different from
a position of the eye of the user.
10. The display apparatus according to claim 1, further comprising:
an electric power supply mode switching unit configured to switch
between a first electric power supply mode in which an electric
power from an external power source is supplied to said light
source, and a second electric power supply mode in which an
electric power from a battery included in said display apparatus is
supplied to said light source; and a control unit configured to
cause said light source to decrease the output intensity of the
infrared ray in response to the switching into the second electric
power supply mode by said electric power supply mode switching
unit.
11. The display apparatus according to claim 1, further comprising
a control unit configured to make a wavefront shape of the infrared
ray emitted from said light source different from a wavefront shape
of the visible light, so that a focal position of the infrared ray
that is deflected by said transmissive deflection unit toward the
eye of the user is a position that is out of the eye of the
user.
12. A display method for displaying an image on a retina of a user
via a transmissive deflection unit, wherein the transmissive
deflection unit includes: a first surface facing an eye of the
user, and a second surface that is a rear surface of the first
surface; a transmissive characteristic for transmitting a visible
light from a second surface side to a first surface side; a
deflection characteristic for deflecting, toward the eye of the
user, the visible light projected from a light source to the first
surface side; and an infrared absorption characteristic for
absorbing an infrared ray projected from the light source to the
first surface side, said display method comprising: emitting a beam
including the visible light forming the image and the infrared ray;
performing two-dimensional scanning on the first surface of the
transmissive deflection unit, using the beam emitted in the
emitting; and changing an output intensity of the infrared beam in
the emitting according to a position on the first surface onto
which the beam is projected for scanning in the scanning.
13. A goggle-type head-mounted display comprising: the display
apparatus according to claim 1; a pair of lenses provided in front
of the eyes of the user and each having said transmissive
deflection unit on a side facing the eyes of the user; and a pair
of temples each having one end connected to corresponding one of
said pair of lenses and the other end fixed to a lateral side of a
head of the user.
14. A vehicle comprising: the display apparatus according to claim
1; and a windshield having said transmissive deflection unit.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to apparatuses which perform
scanning using laser beams, and particularly to a display apparatus
such as a head-up display (HUD) and a head-mounted display
(HMD).
[0003] (2) Description of the Related Art
[0004] Conventional methods used for display apparatuses such as a
head-mounted display (HMD) and a head-up display (HUD) include a
method for performing direct drawing on the retinas of the eyes of
a user by performing two-dimensional scanning using a laser beam
(hereinafter, described as a laser-scanning method) (for example,
see Japanese Patent No. 2932636.) The display apparatus according
to the laser scanning method is also known as a: retinal scanning
display (RSD), retinal irradiation display, retinal direct-draw
display, laser scanning display, direct-view-type display, virtual
retinal display (VRD), and so on.
[0005] In general, in the HMD or HUD according to the laser
scanning method, a scan unit performs two-dimensional scanning
using a laser beam emitted from a laser light source, and a
deflection unit, such as a lens or a mirror, provided in front of
the eyes of the user deflects the beam toward the pupils. Then the
beam passed through the pupils forms an image on the retinas.
[0006] Since the deflection unit is provided in front of the eyes
of the user, there is a problem in that the user's breathing or
sweating cause condensation on the surface of the deflection unit,
resulting in fogging on the deflection unit. The fogging on the
deflection unit decreases efficiency and precision of deflecting
the beam projected by the scan unit toward the pupils of the user.
As a result, a problem of image degradation occurs. Further, in the
case where the deflection unit transmits visible light, such a
problem occurs where transmittance is decreased and viewing
external world becomes difficult.
[0007] Examples of common measures to remove fogging include a
method which uses an infrared heater (for example, see Japanese
Unexamined Utility Model Application Publication No. 4-65648) and a
method in which a heat conductive layer is formed on the rear
surface of a mirror (for example, see Japanese Patent No. 2908696).
There is also a method which uses a transparent resin which absorbs
infrared rays to reduce fogging (for example, see Japanese
Unexamined Patent Application Publication No. 2000-143842).
[0008] Furthermore, examples of methods for detecting a
line-of-sight includes a method in which infrared rays are
projected onto the eyes and the reflected light is used for the
line-of-sight detection (for example, see Japanese Patent No.
2995876), and a method in which a light, reflected from the eyes,
of a laser beam projected for scanning, is used for the
line-of-sight detection (for example, see Japanese Patent No.
3425818).
[0009] However, in the method using the infrared heater and the
like as in Japanese Unexamined Utility Model Application
Publication No. 4-65648, an infrared heater and the like is
necessary in addition to the light source and the scan unit for
displaying an image. Consequently, such problems occur that the
total volume and weight of the HMD and HUD increase or component
cost increases.
SUMMARY OF THE INVENTION
[0010] The present invention is conceived for solving the problems
described above, and it is an objective of the present invention to
obtain a display apparatus, such as a HMD and HUD, which can
reduce, remove and prevent fogging that occurs on a deflection unit
in front of the eyes of a user without addition of an apparatus
dedicated for preventing and removing fogging such as a heater and
a blower, while suppressing the increase in the volume, weight, and
component cost of the apparatus as a whole.
[0011] The display apparatus according to the present invention
displays an image on the retinas of the user. More specifically,
the display apparatus includes: a light source which emits a beam
including a visible light forming the image and an infrared ray;
and a transmissive deflection unit which includes a first surface
facing an eye of the user, and a second surface that is a rear
surface of the first surface. The transmissive deflection unit has:
a transmissive characteristic for transmitting the visible light
from a second surface side to a first surface side; a deflection
characteristic for deflecting, toward the eye of the user, the
visible light projected from the light source to the first surface
side; and an infrared absorption characteristic for absorbing the
infrared ray projected from the light source to the first surface
side.
[0012] This structure provides, in the display apparatus such as a
HMD and HUD, an advantageous effect of reducing, removing and
preventing fogging that occurs on the transmissive deflection unit
in front of the eyes without addition of an apparatus dedicated for
preventing and removing fogging such as a heater and a blower,
while suppressing the increase in the volume, weight, and component
cost of the apparatus as a whole. This structure also makes it
possible to take a fogging prevention measure and display images at
the same time.
[0013] Further, the display apparatus may include a scan unit which
performs two-dimensional scanning on the first surface of the
transmissive deflection unit, using the beam emitted from the light
source; and a control unit which causes said light source to change
an output intensity of the infrared ray according to a position on
the first surface onto which the beam is projected for scanning by
the scan unit. With this structure, the infrared rays can be
concentrated on a necessary area only; therefore, such advantageous
effects can be obtained where energy consumption efficiency of the
infrared rays is enhanced, and temperature rise of the light source
is suppressed, allowing extension of the life of the light
source.
[0014] Further, the control unit may cause the light source to
increase the output intensity of the infrared ray as a position
onto which the beam is projected for scanning by the scan unit
becomes closer to a central part of the first surface. This
structure provides an advantageous effect of preferentially
reducing the fogging on the central part, of the transmissive
deflection unit, where the line-of-sight is concentrated most.
[0015] Further, the display apparatus includes a light detecting
unit which detects a reflected light intensity, on the transmissive
deflection unit, of the beam projected for scanning by the scan
unit. The control unit may cause the light source to change the
output intensity of the infrared ray according to a change of the
reflected light intensity detected by the light detecting unit.
[0016] This structure provides an advantageous effect of reducing
the fogging efficiently in the case where the presence or level of
the fogging differs depending on the part of the transmissive
deflection unit. In addition, it is also possible to suppress the
temperature rise of the light source, which allows extension of the
life of the light source.
[0017] Further, the display apparatus includes a line-of-sight
detecting unit which detects a line-of-sight of the user based on a
reflected light, on the eye of the user, of the visible beam
deflected by the transmissive deflection unit. The control unit may
cause the light source to increase the output intensity of the
infrared ray as a position onto which the beam is projected for
scanning by the scan unit becomes closer to a position where the
line-of-sight of the user detected by the line-of-sight detecting
unit and the first surface intersect with each other. This
structure provides an advantageous effect of preferentially
reducing the fogging on the part where the user is gazing at. In
addition, it is also possible to suppress the temperature rise of
the light source, which allows extension of the life of the light
source.
[0018] Further, the transmissive deflection unit may include: an
infrared absorption layer which is disposed on the first surface
side, transmits the visible light, and absorbs the infrared ray
emitted from the light source; a visible light deflection layer
which is disposed on the second surface side, transmits the visible
light traveling from the second surface side to the first surface
side, and deflects, toward the eye of the user, the visible light
emitted from the light source; and a heat insulation layer which is
disposed between the infrared absorption layer and the visible
light deflection layer, transmits the visible light, and blocks
heat propagation between the infrared absorption layer and the
visible light deflection layer.
[0019] With this structure, it is possible to reduce the
temperature change of the visible light deflection layer even when
the temperature of the infrared absorption layer rises. As a
result, such effects can be obtained where the characteristic
change of the visible light deflection layer, such as decrease or
degradation of the deflection factor, due to the temperature change
can be reduced. Further, the temperature of the infrared absorption
layer can be efficiently raised; and thus, prevention and reduction
of condensation is possible with less laser output.
[0020] Further, the infrared absorption layer may have a different
infrared absorptance according to a position on the first surface.
This structure provides an advantageous effect of reducing
unnecessary removal of the fogging, and decreasing the area of the
infrared absorption layer, which contributes the cost
reduction.
[0021] More particularly, the infrared absorption layer may have a
higher infrared absorptance as a position on the first surface
becomes closer to the central part of the first surface. This
structure provides an advantageous effect of preferentially
reducing the fogging on the central part, of the transmissive
deflection unit, where the line-of-sight is concentrated most.
[0022] Further, the scan unit and the transmissive deflection unit
may be positioned such that the infrared ray specularly reflected
by the transmissive deflection unit is projected onto a position
that is different from a position of the eye of the user. With this
structure, it is possible to reduce the amount of infrared rays
entering the eyes of the user even when the specular reflectance of
the beam on the transmissive deflection unit is high. As a result,
influences of the infrared rays on the eyes can be reduced. In
addition, it is possible to increase the amount of infrared rays
projected onto the transmissive deflection unit without increasing
the influences on the eyes; and thus condensation can be further
reduced.
[0023] Further, the display apparatus may include: an electric
power supply mode switching unit which switches between a first
electric power supply mode in which an electric power from an
external power source is supplied to the light source, and a second
electric power supply mode in which an electric power from a
battery included in the display apparatus is supplied to the light
source; and a control unit which causes the light source to
decrease the output intensity of the infrared ray in response to
the switching into the second electric power supply mode by the
electric power supply mode switching unit. With this structure,
fogging can be strongly reduced when there are plenty of electric
power. Even when there is not enough surplus electric power, the
fogging can be appropriately reduced.
[0024] Further, the display apparatus may include a control unit
which makes a wavefront shape of the infrared ray emitted from the
light source different from a wavefront shape of the visible light,
so that a focal position of the infrared ray that is deflected by
said transmissive deflection unit toward the eye of the user is a
position that is out of the eye of the user. With this structure,
the infrared rays are not focused on the user's eyes; therefore,
the influences of the infrared rays on the eyes can be reduced even
when a part of the infrared rays enters the user's eyes. In
addition, it is also possible to increase the amount of infrared
rays projected onto the transmissive deflection unit without
increasing the influences on the eyes; and thus condensation can be
further reduced.
[0025] The display method according to the present invention
displays an image on a retina of a user via a transmissive
deflection unit. The transmissive deflection unit includes: a first
surface facing an eye of the user, and a second surface that is a
rear surface of the first surface; a transmissive characteristic
for transmitting a visible light from a second surface side to a
first surface side; a deflection characteristic for deflecting,
toward the eye of the user, the visible light projected from a
light source to the first surface side; and an infrared absorption
characteristic for absorbing an infrared ray projected from the
light source to the first surface side. More specifically, the
display method includes: emitting a beam including the visible
light forming the image and the infrared ray; performing
two-dimensional scanning on the first surface of the transmissive
deflection unit, using the beam emitted in the emitting; and
changing an output intensity of the infrared beam in the emitting
according to a position on the first surface onto which the beam is
projected for scanning in the scanning.
[0026] Note that the present invention can be implemented not only
as a display apparatus as described above, but also as an
integrated circuit which implements the functions of the display
apparatus, and as a program causing a computer to execute such
functions. As a matter of course, such a program can be distributed
through a recording medium such as a CD-ROM and a transmission
medium such as the Internet. In addition, the present invention can
also be implemented as an integrated circuit which implements the
functions of such a display apparatus.
[0027] The goggle-type head-mounted display according to the
present invention includes the display apparatus; a pair of lenses
provided in front of the eyes of the user and each having the
transmissive deflection unit on a side facing the eyes of the user;
and a pair of temples each having one end connected to
corresponding one of the pair of lenses and the other end fixed to
a lateral side of a head of the user.
[0028] The vehicle according to the present invention includes the
display apparatus and a windshield having the transmissive
deflection unit.
FURTHER INFORMATION ABOUT TECHNICAL BACKGROUND TO THIS
APPLICATION
[0029] The disclosure of Japanese Patent Application No.
2008-060654 filed on Mar. 11, 2008 including specification,
drawings and claims is incorporated herein by reference in its
entirety.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] These and other objects, advantages and features of the
invention will become apparent from the following description
thereof taken in conjunction with the accompanying drawings that
illustrate a specific embodiment of the invention. In the
Drawings:
[0031] FIG. 1A is a plan view of a display apparatus in Embodiment
1 according to the present invention.
[0032] FIG. 1B is a side view of the display apparatus in
Embodiment 1 according to the present invention.
[0033] FIG. 2 is a diagram showing a detailed structure of the
display apparatus in Embodiment 1 according to the present
invention.
[0034] FIG. 3 is a diagram showing a structure of a transmissive
deflection unit.
[0035] FIG. 4 is a functional block diagram of a control unit.
[0036] FIG. 5A is a diagram showing an example of fogging caused on
the transmissive deflection unit.
[0037] FIG. 5B is a diagram showing a state where the fogging on
the central part has been removed from the state of FIG. 5A.
[0038] FIG. 5C is a diagram showing a state where the fogging on
the is left and central parts have been removed from the state of
FIG. 5A.
[0039] FIG. 5D is a diagram showing a state where the fogging on
the left part has been removed from the state of FIG. SA.
[0040] FIG. 6 is a structural diagram of a display apparatus in
Embodiment 2 according to the present invention.
[0041] FIG. 7 is a diagram showing an example of a vehicle equipped
with a display apparatus according to the present invention.
[0042] FIG. 8 is a diagram showing another example of a vehicle
equipped with a display apparatus according to the present
invention.
[0043] FIG. 9 is a diagram showing an example of a chair equipped
with a display apparatus according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] Hereinafter, embodiments of the present invention shall be
described with reference to the drawings.
Embodiment 1
[0045] With reference to FIGS. 1A to 4, a goggle-type head-mounted
display (HMD) that is a display apparatus in Embodiment 1 according
to the present invention shall be described. Note that: FIG. 1A is
a plan view of the goggle-type HMD; FIG. 1B is a side view of the
goggle-type HMD; FIG. 2 is a detailed view of a portion of FIG. 1A;
FIG. 3 is a diagram showing an example of a specific structure of a
transmissive deflection unit; and FIG. 4 is a functional block
diagram of the goggle-type HMD.
[0046] The goggle-type HMD according to Embodiment 1 of the present
invention includes: a display apparatus, a pair of lenses 11 and 12
provided in front of the user's eyes, and a pair of temples 13 and
14 each having one end connected to a corresponding one of the
lenses 11 and 12 and the other end fixed to each lateral side of
the user's head.
[0047] As shown in FIGS. 1A, 1B, and 2, the display apparatus
includes: light sources 101 and 110; wavefront shape changing units
102 and 109; scan units 103 and 108, transmissive deflection units
104 and 107, control units 105 and 111, and headphone units 106 and
112.
[0048] Note that in this embodiment, the temples 13 and 14 hold the
light sources 101 and 110, the wavefront shape changing units 102
and 109, the scan units 103 and 108, the control units 105 and 111,
and the headphone units 106 and 112, with the transmissive
deflection units 104 and 107 being provided on the lenses 11 and 12
respectively at a side facing the user's eyes.
[0049] Hereinafter, each element of the goggle-type HMD shall be
described in detail. Since each element provided respectively at
the left side and the right side of the user is common, the
description is given below of the light source 101, the wavefront
shape changing unit 102, the scan unit 103, the transmissive
deflection unit 104, the control unit 105 and the headphone unit
106, which are provided at the left side of the user.
[0050] The light source 101 emits a beam including visible light
forming an image and infrared rays. As shown in FIG. 2, the visible
light is a laser light obtained by synthesizing laser lights
emitted from a red laser light source 211, a blue laser light
source 212, and a green laser light source 213. A proper modulation
of the outputs from the respective laser light sources 211, 212,
and 213 makes it possible to emit a laser light having an arbitrary
color. Furthermore, modulation implemented by causing a
later-described wavefront shape changing unit 102 and scan unit 103
to cooperate with each other makes it possible to form an image on
the retina of the user's eye. On the other hand, the infrared rays
are emitted from an infrared laser light source 215.
[0051] Note that the green laser light source 213 in the present
embodiment emits a green laser by combining a semiconductor laser
light source 213L that emits infrared rays and a second-harmonic
generation (SHG) element 213S that converts the infrared rays into
green light. In addition, the infrared laser light source 215
includes a half mirror (optical branching unit) that branches a
part of the infrared rays emitted from the semiconductor laser
light source 213L included in the green laser light source 213. In
other words, the green laser light source 213 and the infrared
laser light source 215 share the same semiconductor laser light
source 213L that emits infrared rays, thereby allowing reduction in
the number of components and costs. Further, examples of the
respective light sources 211, 212, and 213 include a solid-state
laser, a liquid laser, a gas laser, and a light-emitting diode.
[0052] The structure, however, is not limited to the above. A beam,
in which the infrared rays and the green laser are synthesized, may
be emitted from the green laser light source 213 by converting only
a part of the infrared rays emitted from the semiconductor laser
light source 213L into green light using the SHG element 213S.
Further, a unique semiconductor laser light source may also be
adopted for the infrared laser light source 215.
[0053] Note that each of the laser light sources 211, 212, and 213
in FIG. 2 is equipped with a function to modulate laser beams;
however, for modulating the laser beams, a unit which modulates
beams emitted from one of the laser light sources 211, 212, and 213
may also be used in combination with each corresponding one of the
laser light sources 211, 212, and 213.
[0054] The red laser light source 211, the blue laser light source
212, and the green laser light source 213 represent colors,
chrominance, and luminance of pixels to be displayed on the retina
by properly modulating the intensities of the beams respectively
emitted from the red laser light source 211, the blue laser light
source 212, and the green laser light source 213. In addition to
the modulation control, correction control may be performed in
which influence of an optical system from the light source 101 to a
user's eye is taking into account. The optical system includes the
scan unit 103 and the transmissive deflection unit 104. For
example, since the beam projected by the scan unit 103 enters
obliquely to the transmissive deflection unit 104, the rectangle
shape of the display area becomes distorted into a non-rectangle
shape, such as trapezium. The output control of the laser may be
performed in combination with the scan unit 103, so that the
display area becomes a rectangular shape on which an inverse
correction has been performed in advance.
[0055] In addition, the light source 101 in Embodiment 1 includes a
light detecting unit 214 as shown in FIG. 2. The light detecting
unit 214 in Embodiment 1 detects the intensity of the reflected
light, on the transmissive deflection unit 104, of the beam
projected for scanning by the scan unit 103. The light detecting
unit 214 may be a semiconductor imaging element such as a charge
coupled device (CCD), or may also be a photodetection element such
as a photomultiplier and a photodiode.
[0056] The wavefront shape changing unit 102 controls, within a
predetermined range, the spot size of the beams deflected by the
transmissive deflection unit 104 that are to be described below, by
changing the wavefront shapes of the beams emitted from the light
source 101. A "spot size" of a beam, which is hereinafter described
as a spot size on the retina of the user's eye, may be a spot size
on the pupil or cornea, or a spot size on the transmissive
deflection unit 104. The spot size on the retina is the same as the
size of a pixel to be displayed.
[0057] The "wavefront shape" is a three-dimensional shape of a beam
wavefront, and may be a flat surface, spherical surface, or
non-spherical surface.
[0058] As shown in FIG. 2, the wavefront shape changing unit 102
includes a focal-length horizontal component changing unit 201 and
a focal-length vertical component changing unit 202 arranged in
series on an optical path. Therefore, the wavefront shape changing
unit 102 can change curvature radiuses of the wavefront shape in
the horizontal direction and the vertical direction separately.
[0059] The focal-length horizontal component changing unit 201
changes curvature radiuses in the horizontal direction by changing
the distance between a cylindrical lens and a mirror. The
focal-length vertical component changing unit 202 changes curvature
radiuses in the vertical direction by using a cylindrical lens
disposed perpendicular to the cylindrical lens of the focal length
horizontal component changing unit 201. In addition, both the focal
length horizontal component changing unit 201 and the focal length
vertical component changing unit 202 change a beam diameter along
with changing of the curvature.
[0060] Note that it is possible to respond to the horizontal change
more largely by changing the horizontal curvature more largely than
the vertical curvature. This is particularly effective in the case
where the horizontal view angle of the screen is intended to be
made larger than the vertical view angle, or where the horizontal
incident angle of the beam that is incident on the transmissive
deflection unit 104 (to be described later) from the scan unit 103
is larger than the vertical incident angle, as in the case of
having the scan unit 103 on the lateral side of the head.
[0061] Note that in FIG. 2, of the items representing wavefront
shapes, only part of the wavefront shapes, that is, the horizontal
curvature, vertical curvature, and the respective diameters thereof
are changed; however, it is also applicable to provide a unit which
changes, as other items, the distribution of curvatures within the
wavefront, or the shape or the size of the wavefront edge. This
provides an advantageous effect of correcting aberration of the
beams reaching the retina and changing the beam shape.
[0062] In addition, the wavefront shape changing unit 102 in FIG. 2
changes the wavefront shape using a cylindrical lens and a mirror;
however, a variable shape lens such as a liquid crystal lens and a
liquid lens, a diffraction element, or an electro-optic element (EO
element) may also be used. With this, it is possible to reduce the
movable parts in the apparatus as a whole, and also to reduce the
movable range. As a result, reliability of the apparatus can be
improved.
[0063] The scan unit 103 performs two-dimensional scanning on the
transmissive deflection unit 104, using beams outputted from the
wavefront shape changing unit 102. The scan unit 103 is a
single-plate small mirror which can change angles
two-dimensionally, and more specifically is a
micro-electronic-mechanical-system (MEMS) mirror.
[0064] Note that the scan unit 103 may be implemented as a
combination of two or more types of scan units, such as a
combination of a horizontal scan unit and a vertical scan unit. By
having the horizontal scan unit and the vertical scan unit
separately, such advantageous effects can be obtained where they
are not easily influenced by the oscillation of the other scan
unit, and the mechanism can be simplified.
[0065] In addition, the use of the scan unit 103 is not limited to
a method in which a mirror is physically tilted. The scan unit 103
may also be applied in a method in which lenses are moved or
diffraction elements are rotated, and a method in which variable
shape lenses such as liquid lenses, or diffraction elements such as
acoustooptic (AO) elements and electro-optic conversion (EO)
elements are used.
[0066] Further, scanning with visible light and scanning with
infrared rays may be performed by the single scan unit 103.
Further, the scanning with the visible light and the scanning with
the infrared rays can be performed by separate scan units.
[0067] The transmissive deflection unit 104 is a part onto which
the beam is projected for scanning by the scan unit 103. The
transmissive deflection unit 104 includes transmissive
characteristics for transmitting visible light traveling from the
external world (the upper side of FIG. 1A) to the eye of the user,
deflection characteristics for deflecting visible light projected
for scanning by the scan unit 103 toward the pupil of the user's
eye, and infrared absorption characteristics for absorbing
projected infrared rays.
[0068] Hereinafter, in the present embodiment, the description is
given of the case where the whole surface of the transmissive
deflection unit 104 includes the transmissive characteristics, the
deflection characteristics and the infrared absorption
characteristics; however, it may be that only a part of the
transmissive deflection unit 104 includes the transmissive
characteristics, the deflection characteristics and the infrared
absorption characteristics.
[0069] As shown in FIG. 3, the transmissive deflection unit 104 is
disposed on the inner side of the lens 11 (the side facing the
user's eye) in such a manner that a visible light deflection layer
104a, a heat insulation layer 104b and an infrared absorption layer
104c are laminated. More specifically, the infrared absorption
layer 104c is positioned on the surface side facing the user's eye
(hereinafter, referred to as a "first surface"), the visible light
deflection layer 104a is positioned on the rear surface side of the
first surface (hereinafter referred to as a "second surface"), and
the heat insulation layer 104b is positioned between the visible
light deflection layer 104a and the infrared absorption layer
104c.
[0070] The visible light deflection layer 104a transmits visible
light traveling from the second surface side to the first surface
side, and also deflects the visible light emitted form the light
source 101 toward the user's eye. More specifically, the visible
light deflection layer 104a is designed so as to diffract the beams
projected by the scan unit 103, toward the user's eye, by forming,
for example, a photopolymer layer on the internal surface of the
goggle lens 11 and then forming a Lippmann volumetric hologram on
the photopolymer layer.
[0071] On the photopolymer layer, three holograms may be
multiply-formed which reflect lights emitted from the red, green,
and blue light sources 211, 212 and 213, or a trilayer hologram
corresponding to lights of the respective colors may also be
laminated. In addition, it is possible to provide a transmissive
display by manufacturing such that: only the lights having the
wavelength of the light source is diffracted by using the
wavelength selectivity of holograms, and the lights accounting for
the major part of the light from the external world and having
wavelengths other than the wavelength of the light source are not
diffracted. Further, it is also possible to reduce the amount of
infrared rays entering the eye, which provides an advantageous
effect of reducing the influences of the infrared rays on the eye.
Further, deflecting the beams by the diffraction of the hologram
makes it possible to make the transmissive deflection unit 104
thinner.
[0072] The infrared absorption layer 104c transmits the visible
light bidirectionally (from the first surface side toward the
second surface side, and from the second surface side toward the
first surface side), and also includes light absorption
characteristics (infrared absorption characteristics) for absorbing
infrared rays included in the scanning light projected by the scan
unit 103. The part having the light absorption characteristics may
be a polycarbonate resin or equivalent resin which includes
transparency and selectively absorbs infrared rays, as shown in
Japanese Unexamined Patent Publication Application No.
2000-143842.
[0073] The heat insulation layer 104b transmits the visible light
bidirectionally (from the first surface side toward the second
surface side, and from the second surface side toward the first
surface side), and also blocks heat propagation between the visible
light deflection layer 104a and the infrared absorption layer 104c.
More specifically, the heat insulation layer 104b may be a
transparent resin such as a polycarbonate and polyethylene
terephthalate. By having the heat insulation layer 104b, the
temperature change of the visible light deflection layer 104a can
be reduced even when the temperature of the infrared absorption
layer 104c rises. As a result, such an advantageous effect can be
obtained where the characteristic change of the visible light
deflection layer 104a, such as decrease or degradation of the
deflection factor, due to the temperature change can be reduced.
Further, the temperature of the infrared absorption layer 104a can
be efficiently increased; and thus, prevention and reduction of
condensation is possible with less laser output.
[0074] The control unit 105 includes an integrated circuit that
controls each unit of the HMD. As shown in FIG. 4, the control unit
105 may include a central processing unit 501, a memory unit 502,
an input and output control unit 503, and a communication unit 520.
The memory unit 502 stores data used by the control unit 105.
[0075] The input and output control unit 503 controls outputs of
control signals to units as control targets and inputs of signals
from the units. The units include the light source 101, the
wavefront shape changing unit 102, the scan unit 103, the
transmissive deflection unit 104, the headphone unit 106, an
electric power supply (not shown), and the communication unit 520.
The input and output control unit 503 may include, for each kind of
objects to be controlled, a light source input and output control
unit 510, a wavefront-shape-change information input and output
control unit 511, a scanning information input and output control
unit 512, a deflection information input and output control unit
513, a headphone information input and output control unit 514, an
electric power supply information input and output control unit
515, and a communication information input and output control unit
516. The input and output control unit 503 causes execution of
input and output processing, which provides an advantageous effect
of lowering the processing load on the central processing unit 501.
The central processing unit 501 executes information processing by
exchanging signals with the memory unit 502 and the input and
output control unit 503.
[0076] Note that the control unit 105 may include the communication
unit 520 which receives video and audio signals when a wireless
connection is established with peripheral apparatuses such as a
mobile phone. The wireless connection between the HMD and a
peripheral apparatus provides an advantageous effect of improving
wearability when the HMD is mounted.
[0077] The headphone unit 106 includes a speaker which outputs
audio.
[0078] The headphone unit 106 may include a battery for supplying
electric power to the respective units of the display
apparatus.
[0079] The control unit 105 may control the light source 101 so as
to change the output intensity of the infrared rays to be emitted,
according to the position on the first surface of the transmissive
reflection unit 104 onto which the beam is projected for scanning
by the scan unit 103. With this, the infrared rays can be
concentrated only on a necessary area; therefore, such advantageous
effects can be obtained where energy consumption efficiency of the
infrared rays is enhanced, and temperature rise of the light source
101 is suppressed, allowing extension of the life of the light
source 101.
[0080] For example, the control unit 105 may cause the light source
101 to increase the output intensity of the infrared rays as the
position of the beam projected for scanning by the scan unit 103
becomes closer to the central part of the first surface of the
transmissive deflection unit 104. Here, the "central part of the
transmissive deflection unit 104" refers to the central part of the
case where the transmissive deflection unit 104 is divided into
three directionally from left to right defining each as left part,
central part and right part, as shown in FIG. 5A. It may also be
the central part of the case where the transmissive deflection unit
104 is similarly divided into three directionally from up to down.
Further, it may be the central part of the case where the
transmissive deflection unit 104 is divided into three
directionally both from left to right and from up to down,
respectively.
[0081] This provides an advantageous effect of preferentially
reducing the fogging on the central part, of the transmissive
deflection unit 104, where the line-of-sight is concentrated most.
For example, in order to remove the fogging on the central part in
FIG. 5A, output of the infrared rays may be increased only when the
infrared rays are being projected by the scan unit 103 onto the
central part of the transmissive deflection unit 104. By performing
scanning using the infrared rays onto the central part only, or
preferentially onto the central part, it is possible to remove the
fogging on the central part preferentially.
[0082] Note that "the output onto the central part is higher than
the output onto the parts other than the central part" may be the
case where the average output onto the central part is higher than
the average output onto the parts other than the central part, or
the case where the output onto a part of the central part is higher
than the output onto a part of the parts other than the central
part.
[0083] Further, the control unit 105 may determine the level of
fogging on the transmissive deflection unit 104 based on the
detection result of the light detecting unit 214, and control the
light source 101 so as to change the output intensity of the
infrared rays according to the determination result.
[0084] The light detecting unit 214 detects the intensity of the
reflected light, on the transmissive deflection unit 104, of the
beam projected for scanning by the scan unit 103. Condensation on
the surface of the transmissive deflection unit 104 causes the
beams be scattered, which results in the decrease in the intensity
of the reflected light detected by the light detecting unit 214. In
addition, the part of the transmissive deflection unit 104 that the
beam is being projected onto can be specified based on information
such as the angle of the scan unit 103.
[0085] For example, the control unit 105 determines the area in
which the intensity of the reflected light is equal to or less than
a threshold as a "fogging area", and causes the light source 101 to
increase the output intensity of the infrared rays to be projected
for scanning onto the fogging area. This provides an advantageous
effect of reducing the fogging efficiently even when the level of
the fogging or presence of the fogging differs depending on the
area of the transmissive deflection unit 104. In addition, it is
also possible to obtain such an advantageous effect where the
temperature rise of the light source 101 can be suppressed which
allows extension of the life of the light source 101. For example,
in FIG. 5A, it can be presumed based on the detection result of the
light detecting unit 214 that fogging is occurring on the left and
central parts of the transmissive deflection unit 104, and not
occurring on the right part. Hence, as shown in FIG. 5C, it is
possible to reduce the fogging on the left and central parts by
selectively increasing the output intensity of the infrared rays
projected onto the left part and the central part.
[0086] Note that the above case is established when the "diffusion
rate", which is one of the characteristics of the transmissive
deflection unit 104, is high. On the other hand, when the diffusion
rate of the transmissive deflection unit 104 is lower than a
predetermined threshold, the tendency opposite to the above occurs.
In other words, when the level of fogging on the transmissive
deflection unit 104 becomes higher, the intensity of the reflected
light detected by the light detecting unit 214 becomes lower. Thus,
it is necessary to change the determining conditions in the control
unit 105 according to the characteristics of the transmissive
deflection unit 104. Furthermore, it is also known that when the
level of the fogging becomes equal to or greater than the
predetermined value, the above tendency (the correlation between
the level of fogging and the intensity of the reflected light)
becomes inverse.
[0087] As a variation, the light detecting unit 214 may be a
line-of-sight detecting unit which detects the intensity of a
reflected light from the user's eye and detects the line-of-sight
direction of the user based on the detected intensity of the
reflected light. The intensity of the reflected light from the
user's cornea changes depending on the incidence angle on the
surface of the cornea. More specifically, the reflectance of a beam
entering vertically on the surface of the cornea is relatively
high, and the reflectance of a beam entering obliquely on the
surface of the cornea is relatively low. Hence, the line-of-sight
detecting unit can determine the line-of-sight direction of the
user based on the intensity of the reflected light from the user's
cornea.
[0088] The control unit 105 may control the light source 101 so as
to change the output intensity of the infrared rays, according to
the line-of-sight direction of the user. More particularly, the
control unit 105 causes the light source 101 to increase the output
intensity of the infrared rays as the position onto which the beam
is projected for scanning by the scan unit 103 becomes closer to
the position where the user's line-of-sight and the first surface
intersect with each other.
[0089] This provides an advantageous effect of preferentially
reducing the fogging on the area where the user is gazing at. In
addition, it is also possible to obtain such an advantageous effect
where the temperature rise of the light source 101 can be
suppressed, which allows extension of the life of the light source
101. For example, in FIG. 5A, when it can be presumed that the
point of gaze of the user is on the left part, it is possible to
preferentially reduce the fogging on the left part as shown in FIG.
5D.
[0090] Further, as another variation, the open or closed state of
the user's eyelid may be determined based on the reflected light
from the user's eye which is detected by the light detecting unit
214. Eyelids have a lower reflectance of beams than retinas.
Furthermore, since the eyelid gradually closes from the top of the
eyeball toward the bottom, and opens from the bottom toward the
top, the open or closed state of the eyelid can be determined based
on the intensity detection of the reflected light and its change
over time. Based on the determination result, in the case of the
state where the eye is closed (the state where the user is not
looking at anything), the output intensity of the infrared rays may
be decreased.
[0091] Note that the method for detecting a line-of-sight direction
may be a method using a reflected light of a beam projected for
scanning by the scan unit 103, or a method using a reflected light
of a beam emitted from a light source other than the scan unit 103.
For example, in Japanese Patent No. 2995876, the line-of-sight
detection is performed by detecting, with an image sensor, the
infrared rays emitted from an infrared light-emitting diode and
reflected on the eye. Further, in Japanese Patent No. 3425818, the
line-of-sight detection is performed by detecting, with an image
sensor, a reflected light, on the eye, of the beam projected for
scanning by the scan unit 103.
[0092] Further, the intensity of detection when a reflected light
is detected may be represented as a ratio between the intensity of
the emitted light modulated by the light source 101 and the
intensity of the reflected light detected by the light detecting
unit 214. This provides an advantageous effect of reducing
influences of the intensity change of the emitted light according
to the change of the displayed image. Further, it may be that while
scanning is performed, at a constant intensity, using light such as
infrared rays which are not perceived by the eye, and the reflected
light is detected. This makes it possible to provide an
advantageous effect of detecting the reflected light independently
from lightness or color change of the displayed image.
[0093] As described, by the transmissive deflection unit 104 having
the beam absorption characteristics for absorbing infrared rays,
the transmissive deflection unit 104 absorbs the infrared rays
included in the scanning light projected by the scan unit 103, and
the energy of the absorbed infrared rays can reduce, remove, and
prevent condensation that occurs on the surface of the transmissive
deflection unit 104.
[0094] Note that the infrared absorption layer 104c may include the
beam absorption characteristics for making the infrared absorptance
higher than the visible light absorptance. As a result, it is
possible to remove fogging by using infrared rays, and also improve
the luminance of the display at the same time. Further, it is also
possible to obtain such advantageous effects where the amount of
infrared rays entering the eyes can be reduced, and the degradation
of the luminance of the display can be reduced.
[0095] Further, the focal position of the infrared rays emitted
from the light source 101 may be the position different from the
eye of the user such as the retina and the crystalline body. As a
result, the infrared rays are not focused on the user's eye;
therefore, the influences of the infrared rays on the eye can be
reduced even when a part of the infrared rays enters the user's
eye. In addition, it is possible to increase the amount of infrared
rays projected onto the transmissive deflection unit 104 without
increasing the influences on the eye; and thus condensation can be
further reduced.
[0096] Note that as a method for controlling the focal position of
the infrared rays, the infrared laser light source 215 may perform
a modulation control that is different from the modulation control
in the respective laser light sources 211, 212, and 213 (dynamic
control). Alternatively, it may be that the modulation control is
performed by the respective laser light sources 211, 212, and 213
in synchronization with the infrared laser light source 215, and
providing further, for example, a lens on the infrared laser light
source 215 so that the wavefront shape of the infrared rays to be
emitted is always different from that of the visible light (static
control).
[0097] Further, the scan unit 103 and the transmissive deflection
unit 104 may be positioned such that the infrared rays specularly
reflected on the transmissive deflection unit 104 do not enter the
user's eye. This makes it possible to reduce the amount of infrared
rays entering the user's eye even when the specular reflectance of
the beam on the transmissive deflection unit 104 is high, thereby
allowing the reduction of the influences of the infrared rays on
the eye. In addition, it is possible to increase the amount of
infrared rays projected onto the transmissive deflection unit 104
without increasing the influences on the eye; and thus condensation
can be further reduced.
[0098] Furthermore, the infrared absorption layer 104c may include
such beam absorption characteristics that the infrared absorptance
varies depending on the part of the transmissive deflection unit
104 (position on the first surface). As a result, such advantageous
effects can be obtained where unnecessary removal of fogging can be
reduced, and cost can be reduced by decreasing the area of the beam
absorption characteristic part.
[0099] For example, the infrared absorption layer 104c may be made
so as to have a higher infrared absorptance, the closer it is to
the central part of the transmissive deflection unit 104. More
particularly, the thickness of the infrared absorption layer 104c
is made to be thicker, the closer it is to the central part of the
transmissive deflection unit 104. Here, the central part of the
transmissive deflection unit 104 refers to the central part of the
case where the transmissive deflection unit 104 is divided into
three directionally from left to right defining each as left part,
central part and right part, as shown in FIG. 5A. It may also be
the central part of the case where the transmissive deflection unit
104 is similarly divided into three directionally from up to down.
Further, it may be the central part of the case where the
transmissive direction unit 104 is divided into three directionally
both from left to right and from up to down, respectively.
[0100] By the central part having an infrared absorptance higher
than the parts other than the central part, it is possible to
obtain an advantageous effect of preferentially reducing the
fogging on the central part, of the transmissive deflection unit
104, where the line-of-sight is concentrated most. Note that "the
infrared absorptance of the central part is higher than the parts
other than the central part" may be the case where the average
absorptance of the central part is higher than that of the parts
other than the central part, or the case where the absorptance of a
part of the central part is higher than that of a part of the parts
other than the central part.
[0101] In addition, the display apparatus according to the present
invention can obtain electric power for driving units, such as the
light source 101, the wavefront shape changing unit 102, the scan
unit 103, the control unit 105 and the headphone unit 106, from an
external electric power supply (AC power source), or can also
obtain from a battery included in the display apparatus.
[0102] The electric power information input and output control unit
515 (electric power supply mode switching unit) sets a first
electric power supply mode for supplying electric power from an
external power source to each unit when the display apparatus is
connected to the external power source. On the other hand, when the
display apparatus is not connected to the external power source,
the electric power information input and output control unit 515
sets a second electric power supply mode for supplying electric
power from a battery to each unit. Then, the control unit 105
causes the light source 101 to decrease the output intensity of the
infrared rays in response to the switching into the second electric
power supply mode by the electric power information input and
output control unit 515. This makes it possible to strongly reduce
fogging in the case where there are plenty of electric power (first
electric power supply mode), and perform appropriate reduction of
the fogging even in the case where there is not enough surplus
electric power (second electric supply mode).
[0103] As an example of the display apparatus, the description is
given of the case of the goggle-type HMD; however, the HMD may be
other than the goggle-type. Examples of the HMD include a monocular
HMD and a helmet-type HMD. Further, the display apparatus may be
for conveyances such as a vehicle, motorbike, train, airplane,
helicopter, and ship.
[0104] Note that each unit in FIG. 1A through FIG. 4 may be
included in a single case, or in several cases. For example, the
light sources 101 and 110 may be included in separate cases other
than the scan units 103 and 108, or the headphone units 106 and 112
need not to be included. Further, each unit may be arranged
dispersedly. For example, some parts of the control units 105 and
111 may be included in the light sources 101 and 110, or scan units
103 and 108. In addition, each unit may be plural. For example, two
scan units may be included for each of the left eye and the right
eye. Further, each unit may be shared by plural apparatuses. For
example, the light sources 101 and 110 may be shared by two display
apparatuses.
[0105] As described, in the display apparatus according to the
present invention, the transmissive deflection units 104 and 107
include beam absorption characteristics for absorbing beams
projected by the scan units 103 and 108. As a result, it is
possible for the display apparatus such as a HMD and HUD to reduce,
remove, and prevent fogging that occurs on the transmissive
deflection units 104 and 107 in front of the eyes, while
suppressing the increase in the volume, weight and component cost
of the apparatus as a whole.
Embodiment 2
[0106] FIG. 6 is a structural diagram of a display apparatus in
Embodiment 2 according to the present invention. The display
apparatus in Embodiment 2 includes a display element 301, a beam
splitter 302, a projection lens 303, an imaging element 304, and a
transmissive deflection unit 104.
[0107] In the display element 301, a plurality of light sources
each corresponding to respective pixels are arranged
two-dimentionally (arranged in a matrix state). Further, the light
sources respectively emit red light, green light, blue light and
infrared rays. Examples of the display element 301 include a liquid
crystal display apparatus.
[0108] The beam splitter 302 controls the output intensity of the
beams emitted from the display element 301 for each pixel (light
source). The projection lens 303 projects, onto the transmissive
deflection unit 104, the beam emitted from the display element 301
and passed through the beam splitter 302.
[0109] The beam, projected onto the transmissive deflection unit
104 from the display element 301 via the beam splitter 302 and the
projection lens 303, is reflected by the transmissive deflection
unit 104 and enters the imaging element 304 via the projection lens
303 and the beam splitter 302. The imaging element 304 detects, for
example, the level of fogging on the transmissive deflection unit
104 based on the incident light.
[0110] In Embodiment 1, the example has been described where the
beams emitted from the light sources 101 and 110 are projected for
scanning by the scan units 103 and 108 and projected onto the
transmissive deflection units 104 and 107. In Embodiment 2, display
light from the display element 301 that is a two-dimensional
spatial modulation element such as liquid crystal, is projected
onto the transmissive deflection unit 104 through the beam splitter
302, the projection lens 303 and the like. The reflected light from
the transmissive deflection unit 104 follows the optical path again
in a reverse direction, and is detected at the imaging element 304
after passing through the projection lens 303, the beam splitter
302 and the like.
[0111] With this, it is possible to detect the distribution of the
fogging strength on the transmissive deflection unit 104. Then,
projection of the infrared rays onto the part which is detected as
a heavy fogging area allows preferential removal of a part of the
fogging on the transmissive deflection unit 104. As a result,
unnecessary removal of the fogging can be reduced, which provides
an advantageous effect of reducing power consumption, and
suppressing the temperature change of the transmissive deflection
unit 104 as a whole.
[0112] Note that such a display imaging element may be used that
includes functions of both the display element 301 and the imaging
element 304. This provides an advantageous effect of reducing the
number of components and simplifying the optical system.
Embodiment 3
[0113] FIG. 7 is a structural diagram of a head-up display (HUD)
for vehicles in Embodiment 3 according to the present
invention.
[0114] The HUD includes a light source 101, a wavefront shape
changing unit 102, a scan unit 103, a transmissive deflection unit
104, a control unit 105, and a headphone unit 106 which have the
same basic structures as those in Embodiment 1, and thus operate
similarly.
[0115] In Embodiment 3, a video is displayed to a user in a
vehicle. More specifically, the light source 101, the wavefront
shape changing unit 102, and the scan unit 103 are disposed on the
ceiling, and the transmissive deflection unit 104 is disposed
between the driver and the windshield. Note that the transmissive
deflection unit 104 according to Embodiment 3 is hung from the
ceiling in such a manner that the angle can be changed by a holding
part 401.
[0116] As in Embodiment 1, the transmissive deflection unit 104 has
characteristics for transmitting visible light from outside the
vehicle, which allows the user to watch display according to the
present invention while seeing landscape outside the vehicle. This
provides an advantageous effect of allowing the user to watch
information relating to driving actions and a current location such
as a vehicle speed, a caution and alert, navigation guidance.
[0117] As shown in FIG. 7, the light source 101, the wavefront
shape changing unit 102, and the scan unit 103 may be arranged at
positions around the ceiling of the vehicle. This provides an
advantageous effect of not shielding the user's visual field from
outside the window. Further, since they are arranged at the
positions close to the user's eyes, the optical path becomes
shorter, which provides an advantageous effect of increasing
display precision. In addition, the HUD may be structured such that
the light source 101 is disposed at a position, such as a position
below the vehicle body, which is distant from the wavefront shape
changing unit 102, and beams are transmitted from the light source
101 to the wavefront shape changing unit 102 via an optical fiber.
This provides an advantageous effect of decreasing the dimensions
of an area, on the ceiling part, on which the light source 101 is
disposed.
[0118] The control unit 105 may be disposed inside a dashboard of
the vehicle. The control unit 105 may be integrated into a control
apparatus which is not the display apparatus according to the
present invention. For example, the control apparatus may be a
vehicle speed management apparatus, or a guidance control apparatus
(vehicle navigation system). This makes it possible to provide an
advantageous effect of decreasing the total number of control
apparatuses.
[0119] It is not necessary that the headphone unit 106 is in
contact with an ear of the user, and the headphone unit 106 may be
a speaker mounted on the inner surface of the vehicle around the
user, for example, on the inside of a door or the front dashboard
of the vehicle.
[0120] These structures provide, in the display apparatus such as a
HUD, an advantageous effect of reducing, removing, and preventing
fogging that occurs on the transmissive deflection unit 104 in
front of the user's eye, while suppressing the increase in the
volume, weight and component cost of the apparatus as a whole.
Compared to a conventional method for preventing fogging by blowing
air, the present invention does not rely on blowing air; therefore,
it is possible to obtain such advantageous effects of reducing a
problem of air blowback, where air blows back from the window glass
to the face of a passenger, or a problem of dry skin or eyes of the
passenger by the dry air being blown out.
[0121] As an arrangement variation different from FIG. 7, the
structure may be, as in FIG. 8, that the transmissive deflection
unit 104 is integrated into the window glass (attached directly to
the inner surface of the windshield) and beams are projected for
scanning by the scan unit 103 arranged in a lower position. This
allows the transmissive deflection unit 104 and the scan unit 103
to be integrated with the window glass or dashboard, which provides
an advantageous effect that a vehicle can be equipped with the
display apparatus according to the present invention without making
major changes on the appearance of the inside the vehicle.
Embodiment 4
[0122] FIG. 9 is a structural diagram of a chair-type display
apparatus in Embodiment 4 according to the present invention.
[0123] The display apparatus includes a light source 101, a
wavefront shape changing unit 102, a scan unit 103, a transmissive
deflection unit 104, a control unit 105, and a headphone unit 106
which have the same basic structures as those in Embodiment 1, and
thus operate similarly.
[0124] In Embodiment 4, a video is displayed to a user sitting on a
chair.
[0125] As shown in FIG. 9, the light source 101, the wavefront
shape changing unit 102, and the scan unit 103 may be arranged at
positions toward the transmissive deflection unit 104 in front of
the eyes of the user from the chair back. In FIG. 9, those units
are arranged above the user's head, but they may be arranged near
the lateral side of the user's head or below the head.
[0126] The control unit 105 may be disposed below the chair. The
control unit 105 may be integrated into a control apparatus which
is not the display apparatus according to the present invention.
For example, the control apparatus may be a massage control
apparatus. This makes it possible to provide an advantageous effect
of decreasing the total number of control apparatuses.
[0127] The headphone unit 106 may be a headphone in contact with an
ear of the user, or a speaker arranged at a position near a back or
side of the user's head.
[0128] Such structures provide, in the display apparatus mounted on
the chair such as a massage chair, an advantageous effect of
reducing, removing or preventing fogging that occurs on the
transmissive deflection unit 104 in front of the user's eyes
without addition of an apparatus dedicated for preventing and
removing fogging such as a heater and a blower, while suppressing
the increase in the volume, weight and component cost of the
apparatus as a whole.
[0129] Furthermore, the present invention can be implemented not
only as a display apparatus, but also as a program causing a
computer to execute a display method. Further, the display
apparatus according to the embodiments may be implemented by using
an LSI which is a typical integrated circuit. In this case, the LSI
may be integrated into one chip, or may be integrated into plural
chips. For example, the functional blocks other than a memory may
be integrated into one chip LSI. Here, it is called LSI, but it may
also be called IC, system LSI, super LSI, or ultra LSI depending on
the degree of integration.
[0130] Moreover, ways to achieve an integrated circuit are not
limited to the use of the LSI. A special circuit or a general
purpose processor and so forth may also be used for achieving the
integration. A field programmable gate array (FPGA) that can be
programmed or a reconfigurable processor that allows
re-configuration of the connection or configuration of LSI may be
used after LSI is manufactured.
[0131] Further, when a technology for the integrated circuit
replacing LSI is developed with the advance of semiconductor
technology or relevant technology, functional blocks can be
integrated using the technology. Possible field of technology to be
applicable include, for example, biotechnology.
[0132] In addition, the embodiments described above are only
examples. Of course, many modifications are possible in the
exemplary embodiments without materially departing from the novel
teachings and advantages of this invention.
INDUSTRIAL APPLICABILITY
[0133] The display apparatus according to the present invention can
reduce, remove and prevent fogging on the transmissive deflection
unit, and can be applied to a display system, a display method and
the like.
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