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Claims  |
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What we claim is:
1. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array;
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light toward
an observer's eye, said optical means including:
first optical means for at least partially collimating said beams of light
emerging from said plurality of pixels into a plurality of at least
partially collimated diverging beams of light, and
second optical means for converting said plurality of at least partially
collimated diverging beams of light emerging from said first optical means
into said plurality of approximately parallel beams of light and
refracting said plurality of approximately parallel beams of light toward
said observer's eye; and
light-beam limiting means having apertures each having an optical axis
which corresponds to a respective optical axis of one of said plurality of
pixels, said light-beam limiting means being disposed in between said
image display means and said first optical means;
said first optical means being a diffraction optical element array having a
plurality of diffraction optical elements each having an optical axis
which corresponds to a respective optical axis of one of said plurality of
pixels of said image display means, and each of said plurality of
diffraction optical elements being disposed to overlap at least one of
said plurality of diffraction optical elements adjacent thereto; and
said image display means, said light-beam limiting means, and said
diffraction optical element array being disposed so that zero-order light
transmitted by said diffraction optical element array does not enter said
observer's eye.
2. An image display apparatus according to claim 1, wherein each of said
plurality of diffraction optical elements is a Fresnel zone plate.
3. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array; and
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a retina of an observer's eye, each of said plurality of
pixels having a conjugate relationship with said retina of said observer's
eye;
said apparatus being a spectacle-type image display apparatus; and
said apparatus projecting an image directly on both of said observer's
eyes.
4. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array;
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a pupil of an observer's eye; and
stop means having a plurality of apertures respectively corresponding to
said plurality of pixels, for limiting an angle of divergence of light
emerging from each of said plurality of pixels of said image display
means.
5. An image display apparatus according to claim 4, wherein said optical
means includes:
first optical means for at least partially collimating said beams of light
emerging from said plurality of pixels into a plurality of at least
partially collimated diverging beams of light; and
second optical means for converting said plurality of at least partially
collimated diverging beams of light emerging from said first optical means
into said plurality of approximately parallel beams of light and
refracting said approximately parallel beams of light toward said
observer's eye.
6. An image display apparatus according to claim 5, wherein said first
optical means is a diffraction optical element array having a plurality of
diffraction optical elements each having an optical axis which corresponds
to a respective optical axis of one of said plurality of pixels of said
image display means, each of said plurality of diffraction optical
elements being disposed to overlap at least one of said plurality of
diffraction optical elements adjacent thereto.
7. An image display apparatus according to claim 4, wherein said optical
means is a diffraction optical element array having a plurality of
diffraction optical elements each having an optical axis which corresponds
to a respective optical axis of one of said plurality of pixels of said
image display means, each of said diffraction optical elements being
disposed to overlap at least one of said plurality of diffraction optical
elements adjacent thereto.
8. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array, said image display means comprising:
a transmissive flat display panel having said plurality of pixels,
a first microlens array having a plurality of microlenses each having an
optical axis which corresponds to a respective optical axis of one of said
plurality of pixels,
a condenser lens, and
light source means having a minute light-emitting part, said light source
means including a surface illuminant, and a pinhole stop for passing beams
of light from said surface illuminant,
wherein beams of light emitted from said light source means are converged
on said plurality of pixels of said transmissive display panel by said
condenser lens and said first microlens array; and
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a pupil of an observer's eye, said optical means
including:
first optical means for at least partially collimating said beams of light
emerging from said plurality of pixels into a plurality of at least
partially collimated diverging beams of light, said first optical means
being a second microlens array having a plurality of microlenses each
having an optical axis which corresponds to a respective optical axis of
one of said plurality of pixels of said image display means, and
second optical means for converting said plurality of at least partially
collimated diverging beams of light emerging from said first optical means
into said plurality of approximately parallel beams of light and
refracting said plurality of approximately parallel beams of light toward
said observer's eye, said second optical means being a positive lens.
9. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array, said image display means comprising:
a transmissive flat display panel having said plurality of pixels,
a first microlens array having a plurality of microlenses each having an
optical axis which corresponds to a respective optical axis of one of said
plurality of pixels,
a condenser lens, and
light source means having a minute light-emitting part, said light source
means including a surface illuminant, and a pinhole stop for passing beams
of light from said surface illuminant,
wherein beams of light emitted from said light source means are converged
on said plurality of pixels of said transmissive display panel by said
condenser lens and said first microlens array; and
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a pupil of an observer's eye, said optical means being a
second microlens array having a plurality of microlenses each having an
optical axis which corresponds to a respective optical axis of one of said
plurality of pixels of said image display means, a plurality of optical
axes of said plurality of microlenses being eccentric with respect to
corresponding ones of said plurality of pixels of said image display means
at a peripheral part of said image display means.
10. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array, said image display means comprising:
a transmissive flat display panel having said plurality of pixels,
a first microlens array having a plurality of microlenses each having an
optical axis which corresponds to a respective optical axis of one of said
plurality of pixels,
a condenser lens, and
light source means having a minute light-emitting part, said light source
means including a surface illuminant, and a pinhole stop for passing beams
of light from said surface illuminant,
wherein beams of light emitted from said light source means are converged
on said plurality of pixels of said transmissive display panel by said
condenser lens and said first microlens array; and
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a pupil of an observer's eye, said optical means
including:
first optical means for at least partially collimating said beams of light
emerging from said plurality of pixels into a plurality of at least
partially collimated diverging beams of light, said first optical means
being a diffraction optical element array having a plurality of
diffraction optical elements each having an optical axis which corresponds
to a respective optical axis of one of said plurality of pixels of said
image display means, each of said plurality of diffraction optical
elements being disposed to overlap at least one of said plurality of
diffraction optical elements adjacent thereto, and
second optical means for converting said plurality of at least partially
collimated diverging beams of light emerging from said first optical means
into said plurality of approximately parallel beams of light and
refracting said plurality of approximately parallel beams of light toward
said observer's eye.
11. An image display apparatus comprising:
image display means having a plurality of pixels arranged in a
two-dimensional array, said image display means comprising:
a transmissive flat display panel having said plurality of pixels,
a first microlens array having a plurality of microlenses each having an
optical axis which corresponds to a respective optical axis of one of said
plurality of pixels,
a condenser lens, and
light source means having a minute light-emitting part, said light source
means including a surface illuminant, and a pinhole stop for passing beams
of light from said surface illuminant,
wherein beams of light emitted from said light source means are converged
on said plurality of pixels of said transmissive display panel by said
condenser lens and said first microlens array; and
optical means for converting beams of light emerging from said plurality of
pixels into a plurality of approximately parallel beams of light, and for
refracting said plurality of approximately parallel beams of light
directly toward a pupil of an observer's eye, said optical means being a
diffraction optical element array having a plurality of diffraction
optical elements each having an optical axis which corresponds to a
respective optical axis of one of said plurality of pixels of said image
display means, each of said diffraction optical elements being disposed to
overlap at least one of said plurality of diffraction optical elements
adjacent thereto. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to an image display apparatus and, more
particularly, to a spectacle-type image display apparatus which is
designed to project an image directly on the retinas in both the user's
eyes.
Most image information is generally projected on a monitor, a screen, etc.
However, spectacle-type image display apparatuses have also already been
proposed. One such display apparatus is disclosed in Japanese Patent
Application Laid-Open (KOKAI) No. 3-214872 (1991). In the
disclosed'display apparatus, an image of a transmissive image plate, which
is illuminated by a point source, is focused on an eyeball by an ocular
lens, thereby enabling the user to view the image formed directly on the
retina.
The prior art will be explained below with reference to FIG. 17. As shown
in the figure, the prior art image display apparatus comprises a point
source 111, an image plate 112 illuminated by the point source 111, and a
short-focus ocular lens 113 disposed substantially integral with the image
plate 112. A beam of light converges to a focus on a pupil 117 lying in
front of a crystalline lens 116 in an eyeball 114, and an image is formed
on a retina 115 through a pinhole defined by the point of focus. With this
arrangement, the frames of the spectacles can be made compact
advantageously.
In the above-described prior art, a transmissive liquid crystal plate with
a color filter is employed as the image plate 112. However, since the
image plate 112 is not in conjugate relation to the retina 115, it is
necessary in order to obtain a high-definition image to reduce the
diameter of the pinhole formed on the pupil 117 from the viewpoint of
geometrical optics. However, if the diameter of the pinhole is made
excessively small, the projected image becomes unsharp due to the
diffraction of light. Consequently, the above-described prior art cannot
provide a high-definition image.
SUMMARY OF THE INVENTION
In view of these circumstances, it is an object of the present invention to
solve the above-described problems and to provide an image display
apparatus, for example, a spectacle-type image display apparatus, which is
capable of reproducing a high-definition image by projecting pixels at a
proper pitch on the retina in the user's eye.
It is another object of the present invention to provide an image display
apparatus, e.g., a spectacle-type image display apparatus, which is
designed so that even if the number of pixels of an image display device
is increased, there is no lowering in the resolution due to diffraction,
but a high resolution is obtained correspondingly to the number of pixels.
To attain the above-described objects, the present invention provides an
image display apparatus including image display means having a plurality
of two-dimensionally disposed pixels, and optical means for converting a
beam of light emerging from each of the pixels into an approximately
parallel beam of light and for refracting each light beam toward an
observer's eye.
Preferably, the optical means includes first optical means for converging a
beam of light emerging from each of the pixels, and second optical means
for converting a beam of light emerging from the first optical means into
an approximately parallel beam of light and then refracting the light beam
toward the observer's eye. The arrangement may be such that the first
optical means is a microlens array having a plurality of microlenses
formed to correspond respectively to the pixels of the image display
means, and the second optical means is a positive lens. The arrangement
may also be such that the first optical means is a microlens array having
a plurality of microlenses formed to correspond respectively to the pixels
of the image display means, and the array pitch of the microlenses is
approximately equal to the array pitch of the pixels.
Further, the arrangement may be such that the optical means is a microlens
array having a plurality of microlenses formed to correspond respectively
to the pixels of the image display means, and the optical axes of the
microlenses are eccentric with respect to the corresponding pixels at the
peripheral part of the image display means. Alternatively, the array pitch
of the microlenses may be made smaller than the array pitch of the pixels.
When the optical means comprises the first and second optical means, the
first optical means may be a diffraction optical element array having a
plurality of diffraction optical elements formed to correspond
respectively to the pixels of the image display means. The diffraction
optical elements are each disposed to overlap at least one of diffraction
optical elements adjacent thereto. In this case, a light-beam limiting
means having apertures formed to correspond respectively to the pixels may
be disposed in between the image display means and the diffraction optical
element array, and the image display means, the light-beam limiting means
and the diffraction optical element array may be disposed so that
zero-order light transmitted by the diffraction optical element array does
not enter the observer's eye. It should be noted that the diffraction
optical elements are preferably Fresnel zone plates.
Further, the arrangement may be such that the optical means is a
diffraction optical element array having a plurality of diffraction
optical elements formed to correspond respectively to the pixels of the
image display means, and the diffraction optical elements are each
disposed to overlap at least one of diffraction optical elements adjacent
thereto.
When a diffraction optical element array having a plurality of diffraction
optical elements is used, it may comprise two diffraction grating element
surfaces each comprising an array of a plurality of minute diffraction
optical elements.
Further, the image display means may comprise a transmissive flat display
panel having a plurality of pixels, a second microlens array having a
plurality of microlenses formed to correspond respectively to the pixels,
a condenser lens, and light source means having a minute light-emitting
part, so that a beam of light emitted from the light source means is
converged on each pixel of the transmissive display panel by the condenser
lens and the second microlens array. In this case, the light source means
may comprise a surface illuminant, and a pinhole for passing a beam of
light from the surface illuminant.
In the present invention, the image display apparatus includes image
display means having a plurality of two-dimensionally disposed pixels, and
optical means for converting a beam of light emerging from each pixel into
an approximately parallel beam of light and for refracting each light beam
toward the observer's eye. Therefore, a beam of light emerging from each
pixel is converted into a parallel beam of light and led to the eyeball.
Since an array of pixels is reconstructed at a proper pitch on the retina
in the eyeball, the observer can perceive an image. Further, since each
pixel and the retina in the eyeball are in conjugate relation to each
other, the image of each pixel is clearly formed on the retina.
Accordingly, an image that is composed of such pixel images is also clear.
Thus, the observer can perceive a high-definition image.
If a diffraction optical element array is used as at least a part of the
above-described optical means, since the diffraction optical elements can
be disposed to overlap each other, it is unnecessary to reduce the
effective aperture of each diffraction optical element even if the pixel
pitch is reduced. Accordingly, the pixel image becomes even more clear,
and a higher resolution can be obtained.
Still other objects and advantages of the invention will in part be obvious
and will in part be apparent from the specification.
The invention accordingly comprises the features of construction,
combinations of elements, and arrangement of parts which will be
exemplified in the construction hereinafter set forth, and the scope of
the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an optical path diagram showing a first embodiment of the image
display apparatus according to the present invention.
FIG. 2 is an optical path diagram showing a second embodiment of the image
display apparatus according to the present invention.
FIG. 3 is an optical path diagram showing a third embodiment of the image
display apparatus according to the present invention.
FIG. 4 is an optical path diagram showing a modification of the third
embodiment.
FIG. 5 is a plan view of one example of an optimized two-dimensional
display device.
FIG. 6 is an optical path diagram showing the whole optical system of a
fourth embodiment of the image display apparatus according to the present
invention.
FIG. 7 is an enlarged view of a two-dimensional display device and a
Fresnel zone plate block in the fourth embodiment.
FIG. 8 is a plan view of a Fresnel zone plate pattern formed on one of a
pair of substrates.
FIG. 9 is a plan view of a Fresnel zone plate pattern formed on the other
substrate.
FIG. 10 is a plan view of a Fresnel zone plate pattern formed on a single
substrate.
FIGS. 11(a) and 11(b) are an optical path diagram showing the whole optical
system of a fifth embodiment of the image display apparatus according to
the present invention.
FIG. 12 is an optical path diagram showing the whole optical system of a
sixth embodiment of the image display apparatus according to the present
invention.
FIG. 13 is an enlarged view of a two-dimensional display device and a
Fresnel zone plate block in the sixth embodiment.
FIG. 14 is an optical path diagram showing the whole optical system of a
seventh embodiment of the image display apparatus according to the present
invention.
FIG. 15 is an enlarged view of a two-dimensional display device and a
Fresnel zone plate block in the seventh embodiment.
FIGS. 16(a) to 16(d) show the arrangements of diffraction optical elements
employed in the fourth to seventh embodiments of the present invention.
FIG. 17 is an optical path diagram showing a prior art display apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Some embodiments of the image display apparatus according to the present
invention will be described below with reference to the accompanying
drawings.
A first embodiment of the present invention will be explained below with
reference to the optical path diagram of FIG. 1. Referring to FIG. 1, in
front of an eyeball 7 including a crystalline lens 5 and a retina 6, a
condenser lens 4 and a microlens array 3 are disposed in the mentioned
order from the eyeball side. Further, a substrate 1 which is provided with
an LED array 2 for displaying a character, an image, etc. is disposed in
front of the microlens array 3. Although in FIG. 1 the LED array 2 is
shown as a one-dimensional array extending within the plane of the paper,
it is actually a two-dimensional array which also extends in a direction
normal to the plane of FIG. 1. The same is the case with the microlens
array 3.
In the above-described arrangement, a character or an image is formed on
the LED array 2 provided on the substrate 1 by controlling the emission of
light from the LED array 2 by an LED array control means (not shown).
Beams of light emitted from LEDs, which constitute the LED array 2, are
converted into parallel beams of light through the respective microlenses
of the microlens array 3, which are arranged at a pitch approximately
equal to the pitch of the LEDs of the LED array 2, and through the
condenser lens 4, which is common to the LEDs. Then, the parallel light
beams enter the crystalline lens 5. The microlens array 3 mainly functions
to convert a light beam from each LED into an approximately parallel beam
of light, while the condenser lens 4 mainly functions to converge each
parallel light beam on the pupil of the eyeball 7. The light beams
transmitted by the crystalline lens 5 converge on the retina 6 to form the
image of the LED array 2. If the effective aperture of each microlens in
the microlens array 3, that is, the pitch of the LEDS constituting the LED
array 2, is excessively large, the image of the LED array 2 is formed on
the retina 6 as an image composed of points which are unfavorably spread
apart from each other. Conversely, if the effective aperture of the
microlens array 3 is reduced, a diffraction image is formed on the retina
6. Accordingly, the resolution is deteriorated.
Therefore, the optimal pitch of the microlens array 3 (i.e., the optimal
pitch of the LED array 2) is obtained as follows. The resolving power R of
the LED image formed on the retina 6 may be expressed by
R=(0.61.times..lambda.)/NA (.mu.m)
where .lambda. represents the wavelength of incident light, and NA
represents the numerical aperture on the image side. If the F-number on
the image side is represented by F.sub.e,
NA=1/(2F.sub.e)
Since
F.sub.e =f.sub.e /P
the resolving power R is given by
##EQU1##
where f.sub.e represents the focal length (.mu.m) of the eye (it should be
noted that the focal length is defined as the distance from the nodal
point to the focal point), and P represents the cell pitch of the display
device 2, which is approximately equal to the effective aperture of the
microlens array 3. The wavelength of the incident light beam is assumed to
be 0.5 .mu.m.
Assuming that the half field angle is .THETA. and the effective aperture of
the display device 2 is L (.mu.m) and the number of pixels as seen on a
straight line is N, since L=NP, the cell pitch p in the eye is given by
p=2f.sub.e tan.THETA./N=2Ptan.THETA./L.times.f.sub.e
Assuming that the optimal pitch is P.sub.o, p and R are made equal to each
other from the expression of the resolving power R and the expression of
the cell pitch p in the eye as follows:
0.61/P.sub.o =2P.sub.o tan.THETA./L
P.sub.o.sup.2 =0.61L/(2tan.THETA.)=0.31L/tan.THETA.
.thrfore.P.sub.o =0.55(L/tan.THETA.).sup.1/2
If the display device 2 is formed by arranging LEDs respectively emitting
red, blue and green light in a mosaic configuration in order to display a
color image, P.sub.o represents the pitch between each pair of adjacent
cells of the same color.
The number N.sub.o of pixels which is determined when the pitch of the
display device 2 is optimized is given by
N.sub.o =L/P.sub.o =1.82(L.multidot.tan.THETA.).sup.1/2
If the half field angle 8 in the horizontal direction and the effective
aperture L of the display device 2 are assumed to be .THETA.=15.degree.
and L=30.times.10.sup.3 .mu.m, respectively,
the number of cells in the horizontal direction=1.82(30.times.10.sup.3
.multidot.tan15.degree.).sup.1/2 =163
the pitch in the horizontal direction=184 .mu.m
If the effective aperture of the display device 2 in the vertical direction
is assumed to be 20.times.10.sup.3 .mu.m,
the number of cells in the vertical direction=1.82(20.times.10.sup.3
.multidot.tan10.1.degree.).sup.1/2 =108
the pitch in the vertical direction=185 .mu.m
Accordingly, the total number of pixels is 163.times.108=17,604 (pixels).
Assuming that the cell aperture of the display device is .0., the aperture
of the cell image formed in the eye is .psi. and f.sub.o represents the
composite focal length of the microlens array 3 and the condenser lens 4,
since the magnification M of projection of the LED cell on the fundus
oculi is M=f.sub.e /f.sub.o, the following relationship is given:
.psi.=M.0.=f.sub.e .psi./f.sub.o
In order to arrange cells so that the boundaries of the cell images lie in
contact with each other on the fundus oculi, the following condition must
be satisfied:
.psi.=p
f.sub.e .psi.f.sub.o =p=2f.sub.e tan.THETA./N
.thrfore..psi.=2f.sub.o tan.THETA./N
If f.sub.o is assumed to be 2,000 .mu.m,
.psi..sub.x =2.times.2,000.times.tan15.degree./163=6.5 .mu.m (horizontal
direction)
.psi..sub.y =2.times.2,000.times.tan10.1.degree./108=6.5 .mu.m (vertical
direction)
If the cell aperture is larger than the above, the resolution lowers,
whereas, if the cell aperture is smaller than the above, the resolution
does not rise substantially, and the cell boundaries become conspicuous.
In a case where the display device 2 is formed by arranging LEDs
respectively emitting red, blue and green light in a mosaic configuration,
the resolution will not lower even if cell images of different colors
overlap each other. In such a case, therefore, .psi. may be from two to
four times that represented by the above expression.
It will be clear from the above examination that an optimal image can be
obtained by arranging two-dimensional display cells as shown in the plan
view of FIG. 5.
Next, a second embodiment of the present invention will be explained with
reference to the optical path diagram of FIG. 2. Referring to the figure,
in front of an eyeball 7 including a crystalline lens 5 and a retina 6,
microlens arrays 16 and 13 are disposed in the mentioned order from the
eyeball side. Between the microlens arrays 16 and 13 is provided a liquid
crystal layer 15 that is sandwiched between parallel flat plates 14a and
14b for displaying a character or an image. Although in FIG. 2 the array
of liquid crystal cells 15-l to 15-n is shown as a one-dimensional array
extending within the plane of the paper, it is actually a two-dimensional
array which also extends in a direction normal to the plane of FIG. 2. The
same is the case with the microlens arrays 16 and 13. A condenser lens 12
is provided in front of the microlens array 13. Further, a pinhole 11 and
a surface illuminant 10 are disposed in front of the condenser lens 12.
In the above-described arrangement, a character or an image is formed on
the liquid crystal layer 15, which is sandwiched between the parallel flat
plates 14a and 14b, by controlling the applied voltage for each of the
cells 15-l to 15-n by a liquid crystal control means (not shown). Beams of
light emitted from the external light source and transmitted by the liquid
crystal cells 15-l to 15-n are converted into parallel beams of light
through the microlens array 16 having a somewhat smaller pitch than the
pitch of the liquid crystal cells 15-l to 15-n, and the parallel light
beams enter the crystalline lens 5. The light beams transmitted by the
crystalline lens 5 converge on the retina 6 to form images of the liquid
crystal cells. A parallel light beam that is transmitted by the m-th
microlens counted from the center of the microlens array 16 has an
inclination with respect to the optical axis, as shown in the figure. If
the focal length of the microlens array 16 is assumed to be f.sub.o, the
angle of inclination is tan.sup.-1 {(.xi..times.m)/f.sub.o }, where .xi.
represents the difference in pitch between the liquid crystal cells 15-l
to 15-n and the microlens array 16. Thus, the condenser lens 4 that is
employed in the first embodiment is unnecessary in this embodiment.
The liquid crystal cell aperture (the aperture of the display part in the
cell) is preferably (2f.sub.o tan.THETA.)/N, as described in the first
embodiment. The numerical value of the cell aperture is likely to be as
small as several .mu.m. However, it is theoretically difficult to make the
liquid crystal cell aperture smaller than the thickness (about 10 .mu.m)
of the liquid crystal layer. If the cell aperture is excessively large,
the cell images formed on the retina 6 overlap each other, so that the
resolution is deteriorated. Therefore, an external light source that
comprises the surface illuminant 10, the pinhole 11, the condenser lens 12
and the microlens array 13 is provided, as shown in the figure. Light
beams emitted from the surface illuminant 10 enter the condenser lens 12
through the pinhole 11. The light beams incident on the condenser lens 12
are converged on the respective liquid crystal cells 15-l to 15-n by the
condenser lens 12 and the microlens array 13. The diameter of a spot that
illuminates each liquid crystal cell is determined by the | | |
