Light valve apparatus, and projection display system and view-finder system employing said light valve apparatus

A light valve apparatus in which a first lens array, a second lens array, and a light valve are arranged sequentially from an incident light side, and a focal length of each of microlens elements for the first lens array is set to be shorter than a focal length of each of microlens elements for the second lens array, and the respective microlens elements of the second lens array are adapted to form real image corresponding to an imaginary object on a focal point of the respective microlens elements of the first lens array, on corresponding pixels of the light valve. By the first lens array, a plurality of very small light source images corresponding to the light source are formed, and light emitted from the plurality of very small light source images are incident upon the respective microlens elements of the second lens array so as to be projected onto the pixels of the light valve. Therefore, since the light incident upon openings of the light valve can be increased without thinning an incident side glass substrate of the light valve, substantial aperture ratio of the light valve apparatus may be improved. When the above light valve apparatus is used for a projection display system, projected images can be more brightened, while, if the above light valve apparats is applied to a view-finder system, it becomes possible to reduce the power consumption and also to improve brightness of the display images.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a light valve apparatus, and a projection 
display system and a view-finder system employing said light valve 
apparatus. 
Conventionally, there has been known a system in which optical images 
corresponding to video signals are formed on a light valve, and light is 
irradiated onto the optical images for projection thereof onto a large 
screen through magnification by a projection lens. Recently, there has 
been disclosed a projection display unit which employs a liquid crystal 
panel as a light valve, for example, in U.S. Pat. No. 5,042,929 to Tanaka 
et al., to which attention has been directed from the viewpoint that the 
projection unit may be made compact as a whole. 
In order to obtain a projection image at high image quality, it has been a 
main tendency that the liquid crystal panel employs twist nematic (TN) 
liquid crystal as the material, and TFT (thin film transistors) are used 
for respective pixels (i.e., picture elements) as switching elements so as 
to adopt an active matrix type, with three sheets of liquid crystal panels 
being used for red, green and blue respectively. 
FIG. 23 shows one example of conventional constructions of an optical 
system for a projection display system employing the liquid crystal panel. 
In the known arrangement of FIG. 23, light emitted from a light source 11 
is incident upon a color separating optical system constituted by dichroic 
mirrors 12 and 13, and a flat mirror 14 so as to be separated into light 
rays in three primary colors of red, green and blue. Each primary light 
color passes through incident side polarizing plates 18, 19 and 20 after 
having been transmitted through field lenses 15, 16 and 17 and is incident 
upon the liquid crystal panels 21, 22 and 23. The optical images formed as 
variations of rotatory polarization in the liquid crystal panels 21, 22 
and 23 according to video signals are formed into optical images varying 
in transmittance by the action of the incident side polarizing plates 18, 
19 and 20, and emitting side polarizing plates 24, 25 and 26. Light rays 
emitted from the liquid crystal panels 21, 22 and 23 are combined into one 
light by a color combining optical system constituted by dichroic mirrors 
27 and 28 and a flat mirror 29. The combined light is incident upon a 
projection lens 30, and the optical images on the three liquid crystal 
panels 21, 22 and 23 are projected onto a projection screen (not shown) 
through magnification by the lens 30. 
FIG. 24 shows the construction of a conventional TFT (thin film transistor: 
referred to as TFT hereinafter) liquid crystal panel. 
In FIG. 24, the TFT liquid crystal panel generally includes two sheets of 
glass substrates 41 and 42 disposed through a predetermined interval and 
sealed therearound by a sealing resin for defining a closed space 
therebetween, in which TN liquid crystal 43 is enclosed. 
At the side of the liquid crystal layer 43 of the incident side glass 
substrate 42, a common electrode 44 of a transparent conductive film is 
provided, while at the side of the liquid crystal layer 43 of the emitting 
side glass substrate 42, pixel electrode 45 by a transparent conductive 
film are formed in a matrix pattern, with TFT 46 being formed in the 
vicinity of the respective pixel electrodes 45 as switching elements. On 
the common electrode 44 and the pixel electrode 45, alignment films for 
orientating the TN liquid crystal in a predetermined state are formed. At 
the incident side and the emitting side of the liquid crystal panel, the 
polarizing plates 47 and 48 are disposed, with absorbing axes thereof 
directed in a predetermined direction. In order to prevent erroneous 
functions of the TFT 46 by the intense light incident upon the liquid 
crystal panel, black matrixes 49 of metallic thin films are formed at the 
side of the liquid crystal layer 43 of the incident side glass substrate 
41 for shielding the TFT 46 and wirings against light. Upon impression of 
signal voltages to the respective pixels through the TFT 46, the rotatory 
polarization of the liquid crystal layer for the respective pixels is 
varied, whereby the transmittance of each of the pixels can be controlled 
by the action of the two polarizing plates 47 and 48. Thus, the images as 
the variation of the transmittance are displayed on the liquid crystal 
panel. 
Incidentally, light to be utilized by the TFT liquid crystal panel in the 
construction as shown in FIG. 24 is limited to the light transmitted 
through the black matrix 49, and brightness of the projected images is 
proportional to the aperture ratio (i.e., ratio of the area for all the 
openings 50 of the black matrix 49 to a total area of the display region) 
of the liquid crystal panel. If light incident upon the non-opening 
portions 51 of the black matrix 49 can also be utilized, the projected 
images may be made brighter, with an improved energy utilizing efficiency. 
Accordingly, there has also been conventionally disclosed, for example, in 
U.S. Pat. No. 5,052,783 to Hamada et al., a method for brightening 
projected images by disposing a lens array plate close to the incident 
side of the liquid crystal panel. 
FIG. 25 shows an example of conventional light valve apparatuses in which a 
lens array plate is combined with the liquid crystal panel. 
In FIG. 25, a lens array plate 61 has a plurality of microlens elements 64 
formed in a matrix pattern on a surface of a transparent substrate 62 at 
the side of the liquid crystal panel 63. The lens array plate 61 is 
disposed close to the liquid crystal panel 63 so that the microlens 
elements 64 and the pixels 50 of the liquid crystal panel 63 correspond to 
each other. Light incident upon the lens array plate 61 is converted into 
a converged light by the microlens elements 64 and incident upon the pixel 
50. Since light incident upon the non-opening portions 51 of the black 
matrix 49 is also incident upon the opening portions 50, the substantial 
aperture ratio of the liquid crystal panel 63 is improved, and the 
projected images are further brightened. 
For obtaining very fine projected images by the construction as shown in 
FIG. 25, it may be so arranged to increase the number of pixels of the 
liquid crystal panel. If the dimensions of the display screens of the 
liquid crystal panels are the same, the pixel pitch is to be decreased, in 
which case, however, problems as described hereinbelow will take place. 
In the case where a lens array is employed, contracted real images of the 
light source are formed on the pixels 50 of the liquid crystal panel 63. 
When the size of such real images is larger than that of the pixel 50, 
although the substantial aperture ratio may be improved upon incidence of 
parallel light rays, the projected images will not be brightened. For 
reducing the size of the real image of the light source, a focal length of 
the microlens element 64 for the lens array plate 61 must be reduced, and 
for this purpose, it is necessary to make the glass substrate 41 at the 
incident side thinner. However, if the incident side glass substrate 41 is 
made thin, it becomes difficult to make the thickness of the liquid 
crystal layer 43 uniform. In order to overcome such an inconvenience, 
there has also been conventionally proposed, for example, in Japanese 
Patent Laid-Open Publication Tokkaihei No. 2-302726 by Ito et al., a 
method for disposing lens elements within an incident side glass substrate 
41. In connection with the above, however, in the case where a lens array 
of a refractive index distribution type is prepared by the ion exchange 
method, it is required to employ a glass material containing alkali ion as 
the glass substrate, and in this case, there is a problem that 
characteristics of the TFT are undesirably deteriorated by the elution of 
the alkali ion. Meanwhile, when the lens array is formed between two glass 
substrates, materials different in the refractive index must be combined, 
and in this case, due to a difference in the thermal expansion 
coefficient, it is also difficult to make the thickness of the liquid 
crystal layer uniform in a broad temperature range. Anyhow, by the 
practice to form the microlens elements within the incident side glass 
substrate, it is difficult to display images at high quality on the liquid 
crystal panel. Thus, there has been a problem that after all, fine and 
bright projection images at high quality can not be readily obtained. 
Subsequently, with respect to a video camera, it is necessary to make the 
entire unit compact in size and light in weight for improving portability 
thereof, and employment of a liquid crystal panel for the view-finder is 
considered to reduce the size of the video camera as a whole. For making 
the view-finder compact and light weight, and displaying an image at high 
image quality on the liquid crystal panel, size of the display screen for 
the liquid crystal panel must be reduced, with an increase in the number 
of pixels. In other words, the pitch of the pixels for the liquid crystal 
panel must be decreased. In that case, however, the aperture ratio of the 
liquid crystal panel is made small, and thus, the displayed image is dark. 
Although a brighter light source may be employed for making the displayed 
image brighter, power consumption by the light source becomes large 
thereby, and continuous using time by one charging of a battery in 
undesirably reduced. 
2. Description of the Prior Art 
SUMMARY OF THE INVENTION 
Accordingly, an essential object of the present invention is to provide a 
light valve apparatus which is capable of displaying bright projection 
images without reducing thickness of a glass substrate, even in the case 
where pixel pitch for a liquid crystal panel is small, and a projection 
display system and a view-finder system providing a bright display image 
at, a low power consumption by employing the light valve apparatus as 
referred to above. 
Another object of the present invention is to provide a light valve 
apparatus, and a projection display system and a view-finder system 
employing said light valve apparatus, which are simple in construction and 
stable in functioning at high reliability, and can be readily manufactured 
at low cost. 
In accomplishing these and other objects, according to one aspect of the 
present invention, there is provided a light valve apparatus which 
includes a light valve in which a plurality of pixels are arranged in a 
matrix pattern, a first lens array means in which a plurality of microlens 
elements are arranged in a matrix pattern similar to the pixel arrangement 
of the light valve, and which is disposed at an incident side of said 
light valve, and a second lens array means in which a plurality of 
microlens elements are arranged in a matrix pattern similar to the pixel 
arrangement of said light valve, and which is disposed between said light 
valve and said first lens array means. A focal distance of each of the 
microlens elements of said first lens array means is equal to or shorter 
than a focal distance of each of the microlens elements of said second 
lens array means, and the respective microlens elements of said second 
lens array means are adapted to form real image of an imaginary object on 
a focal point of the plurality of the microlens elements of said first 
lens array means, on the corresponding pixels of said light valve. 
In another aspect of the present invention, the light valve apparatus 
further includes a third lens array means in which a plurality of 
microlens elements are arranged in a matrix pattern similar to that of the 
pixel arrangement of said light valve, and which is disposed between said 
first lens array means and said second lens array means. The respective 
microlens elements of said third lens array means are adapted to form 
imaginary objects on principal planes of the respective microlens elements 
of said first lens array, on principal planes of the plurality of the 
microlens elements of said second lens array means for said second lens 
array means. 
In still another aspect of the present invention, it is so arranged that an 
optical axis of each of the microlens elements of said second lens array 
means is aligned with an optical axis of the corresponding microlens 
element of said first lens array means. 
In a further aspect of the present invention, it is so arranged that said 
light valve has the pixels thereof subjected to a square arrangement, and 
an optical axis of each of said microlens elements of said first lens 
array means passes through a middle point of a line connecting centers of 
neighboring two microlens elements of said second lens array means or a 
center of a square constituted by centers of the neighboring four 
microlens elements of said second lens array means. 
In a still further aspect of the present invention, the arrangement is so 
made that said light valve has the pixels thereof subjected to a delta 
arrangement, and an optical axis of each of said microlens elements of 
said first lens array means passes through a middle point of a line 
connecting centers of neighboring two microlens elements of said second 
lens array means or a center of a triangle constituted by connecting 
centers of the neighboring three microlens elements of said second lens 
array means. 
In another aspect of the present invention, there is provided a projection 
display system which includes a light source, a light valve apparatus upon 
which light emitted from said light source is incident and in which 
optical images are formed according to video signals, and a projection 
lens for projecting said optical images onto a screen, with any one of the 
light valve apparatuses being employed as a light valve means. 
In still another aspect of the present invention, there is provided a 
view-finder system which includes a light source, a light valve apparatus 
upon which light emitted from said light source is incident and in which 
optical images are formed according to video signals, and a magnifying 
lens for magnifying said optical images, with any one of the above light 
valve apparatuses being employed as a light valve means. 
By the arrangements according to the present invention as described so far, 
an improved light valve apparatus with a large aperture ratio may be 
realized without any restriction to the light valve, and moreover, by 
employing this light valve apparatus, there are such favorable effects 
that a projection display system with bright projection images, and a 
view-finder system having bright display images at a low power consumption 
can be advantageously provided.

DETAILED DESCRIPTION OF THE INVENTION 
Before the description of the present invention proceeds, it is to be noted 
that like parts are designated by like reference numerals throughout the 
accompanying drawings. 
Before describing embodiments according to the present invention, principle 
for a light valve apparatus according to the present invention will be 
explained hereinbelow. 
Referring now to the drawings, there is shown in FIG. 1, a model of a light 
valve apparatus according to the present invention, in which a first lens 
array means 71, a second lens array means 72, and a light valve 73 are 
sequentially disposed in that order from a light incident side. Here, it 
is assumed that each of the light valve 73, the first lens array means 71, 
and the second lens array means 72 is very thin, with air present in 
spaces therebetween. The light valve 73 has its pixels 74 arranged in a 
square pattern. In the first lens array means 71 and the second lens array 
means 72, square microlens elements 75 and 76 are arranged also in a 
square pattern respectively, and there is no non-lens region in any of the 
lens array means 75 and 76. It is assumed that all of the microlens 
elements 75 and 76 are thin and ideal lenses without any aberration. It is 
also assumed that pitches of the microlens elements 75 and 76 for the 
first lens array means 71 and the second lens array means 72 are exactly 
the same as the pitch of the pixels 74 for the light valve 73, and an 
optical axis 77 of each of the microlens element 75 and an optical axis 78 
of the corresponding microlens element 76 are aligned with each other, and 
that each of the optical axes 77 and 78 passes through a center 79 of the 
pixel 74 for the light valve 73. 
An optical path diagram corresponding to FIG. 1 is shown in FIG. 2. Upon 
incidence of light 80 from a light source (not shown here) on the first 
lens array means 71, each of the microlens elements 75 of the first lens 
array means 71 forms a very small real image 82 corresponding to the light 
source on each focal point 81. In other words, a first very small light 
source group 83 is formed at the emitting side of the first lens array 
means 71. Each of the microlens elements 76 of the second lens array means 
72 forms an equal size real image 84 of the very small light source 82 
rotated through 180.degree.. In other words, a second very small light 
source group 85 is formed at the emitting side of the second lens array 
means 72. The pitch of the first very small light source group 83 and the 
pitch of the second very small light source group 85 are equal to each 
other. In the case where the optical axis 77 of each of the microlens 
elements 75 is aligned with the optical axis 78 of the corresponding 
microlens element 76, the second very small light source group 85 formed 
by the respective microlens elements 76 entirely overlaps the respective 
very small light sources 84. When the pixel pitch of the light valve 73 is 
equal to the pitch of the second very small light source group 85, the 
respective pixels 74 of the light valve 73 can be overlapped with the 
respective very small light sources 84 of the second very small light 
source group 85. 
If a distance from a focal point 81 to a principal point of the microlens 
element 76 is longer than a focal distance of the microlens element 75, 
light emitted from one microlens element 75a of the first lens array means 
71 is incident upon the plurality of microlens elements 76a, 76b and 76c 
of the second lens array means 72, and the light emitted therefrom is 
incident upon any of the pixels of the light valve 73. Thus, upon one 
pixel of the light valve 73, light is incident from the plurality of the 
microlens elements 76a, 76b and 76c of the second lens array means 72. 
A focal length of each of the microlens elements 75 for the first lens 
array means 71 is represented by f.sub.1, and that of each of the 
microlens elements 76 for the second lens array means 72, by f.sub.2. The 
respective very small light sources 84 of the secondary small light source 
group 85 may be all overlapped as represented by equations given below. 
EQU b=2f.sub.2 (1) 
EQU c=2f.sub.2 (2) 
where b is the distance from the focal point 81 of the first lens array 
means 71 to the principal point of the second lens array means 72, and c 
is the distance from the principal point of the second lens array means 72 
to the pixel 74 of the light valve 73. 
Moreover, when the distance from the principal point of the first lens 
array means 71 to the focal point 81 is represented by a, the relation as 
follows is established. 
EQU a=f.sub.1 (3) 
In a embodiment, the focal length f.sub.1 is equal to or shorter than the 
focal length f.sub.2, i.e., a.ltoreq.b/2. 
Furthermore, a model of the light valve apparatus in the case where a third 
lens array according to the present invention has been added is shown in 
FIG. 3, in which the first lens array means 71, the second lens array 
means 72, a third lens array means 91 and the light valve 73 are disposed 
in that order from an incident side. Here, it is also assumed that each of 
the light valve 73, the first lens array means 71, and the second lens 
array means 72 and the third lens array means 91 is very thin, with air 
present in the spaces therebetween. The constructions of the light valve 
73, the first lens array means 71, and the second lens array means 72, and 
the arrangements of the respective pixels 74, and the respective microlens 
elements 75 and 76 are the same as those in FIG. 1. In the third lens 
array means 91, square microlens elements 92 are arranged in a square form 
respectively, and there is no non-lens region therein. It is assumed that 
all of the microlens elements 92 are thin and ideal lenses without any 
aberration. It is also assumed that pitch of the microlens elements 92 for 
the third lens array means 91 is exactly the same as the pixel pitch of 
the light valve 73, and an optical axis 93 of each of the microlens 
elements 92 for the third lens array means 91, is aligned with the 
corresponding optical axis 77 of each of the microlens elements 75 for the 
first lens array means 71, and the corresponding optical axis 78 of each 
of the microlens elements 76 for the second lens array means 72. 
In an optical path diagram in FIG. 4 corresponding to FIG. 3, light 94 
incident from the light source forms, by each of the microlens elements 75 
of the first lens array means 71, a very small real image 82 corresponding 
to the light source on each focal point 81. The third lens array means 91 
is so disposed that the very small light source images 82 by the 
respective microlens elements 75 for the first lens array means 71 are 
formed on the principal plane of the respective microlens elements 92, and 
accordingly, the images of the very small light source 82 formed on the 
principal plane of each of the microlens elements 92 of the third lens 
array means 91 is formed on each of the pixels of the light valve 73 by 
each of the microlens elements 76 of the second lens array means 72. 
FIG. 5 shows an optical path diagram corresponding to FIGS. 3 and 4. Each 
of the microlens elements 92 of the third lens array means 91 forms the 
image of an imaginary object on the principal plane of each of the 
microlens elements 75 for the first leans array means 71, on the principal 
plane of each of the microlens elements 76 of the second lens array means 
72, whereby the light incident upon each of the microlens elements 75 of 
the first lens array 71 and passing through the end portion 96 of the very 
small light source 82 formed on the focal point 81 thereof, is incident 
upon the principal plane,of each of the microlens elements 76 for the 
second lens array means 72 by each of the microlens elements 92 from the 
third lens array means 91. Accordingly, the light rays from the first very 
small light source image group formed by each of the microlens elements 75 
of the first lens array 71 are incident upon the corresponding microlens 
element 76 for the second lens array means 72 so as to form a second very 
small light source image 84, and the light from the end portion 96 of the 
very small light source 82 can be incident upon each of the pixels 74 of 
the light valve 73. 
As shown in FIG. 4, when the third lens array means 91 is further added, 
the light 94 incident in a parallel relation with the optical axis passes 
through the focal point 81 of each of the microlens elements 75 for the 
first lens array means 71 which is on the principal plane of each of the 
microlens elements 92 for the third lens array means 91, and is incident 
upon each of the microlens elements 76 of the second lens array means 72. 
Accordingly, on the assumption that transmittance of the third lens array 
means 91 is at 100%, the light incident upon the first lens array means 71 
in a parallel relation with the optical axis 77 may be incident upon each 
of the corresponding microlens elements 76 of the second lens array means 
72 without any loss. 
On the other hand, in the absence of the third lens array means 91, light 
rays 98a and 98b (FIG. 5) which are part of the light not parallel with 
the optical axis 77 of the first lens array means 71 are not incident upon 
each of the corresponding microlens elements 76a and 76c of the second 
lens array means 72, but enter the microlens elements 76d and 76e to be a 
loss. Therefore, by disposing the third lens array means 91, the light not 
parallel with the optical axis 77 and incident upon each of the microlens 
elements 75 of the first lens array means 71 can be efficiently incident 
upon each of the corresponding microlens elements 76a, 76b and 76c of the 
second lens array means 72. Thus, the light rays emitted from the very 
small light source image group 83 formed by each of the microlens elements 
75 of the first lens array means 71 can be effectively utilized. 
The equations (1), (2) and (3) referred to earlier may be established even 
when the third lens array means 91 is provided. Moreover, when the focal 
length of each of the microlens elements 92 for the third lens array means 
91 is denoted by f.sub.3, the relation will be represented by an equation 
as follows. 
##EQU1## 
In the models as shown in FIGS. 1 and 3, although c is restricted by the 
light valve 73, there is no factor which will restrict a+b. Therefore, the 
focal length f.sub.1 of the first lens array means 71 can be shortened, as 
a result of which the size of each of the very small light sources 84 of 
the second very small light source group 85 is also reduced. Meanwhile, as 
described above, the light rays emitted from the first lens array means 71 
entirely reach all of the pixels 74 of the light valve 73 through the 
plurality of the microlens elements 76 of the second lens array means 72, 
and substantial aperture ratio of the light valve apparatus as shown in 
FIG. 1 may be improved. If all the light rays emitted from the respective 
pixels of the light valve are incident upon the projection lens, the 
projected image will become brighter. 
Subsequently, preferable conditions in the case where the substantial 
aperture ratio is to be improved by the arrangements shown in FIG. 1 to 
FIG. 5 will be explained. 
FIGS. 6 and 7 are optical path diagrams representing general cases in which 
light is incident upon one pixel of the light valve from the plurality of 
the microlens elements of the second lens array means. 
In the states as shown in FIGS. 6 and 7, although the lens element 76b is 
utilized in the entire effective region, only part of such effective 
regions is utilized in the microlens elements 76a and 76c. In this case, 
in the projection lens, since a middle region of its pupil is not 
utilized, there is a considerable wasteful portion. In order to reduce 
such wasteful portion to minimum, it may be so arranged that the light 
rays emitted from the edge portion 86 of one microlens element 75a of the 
first lens array means 71 pass through the edge portion 87 of the assembly 
of the plurality of the neighboring microlens elements 76a, 76b and 76c. 
Such conditions may be represented by an equation, 
##EQU2## 
wherein f.sub.1 is the focal length of each of the microlens elements 75 
of the first lens array means 71, f.sub.2 is the focal length of each of 
the microlens elements 76 of the second lens array means 72, and m is a 
positive integer. 
In FIGS. 2 and 4, although there is shown the case where, when the light 
emitted from one microlens element 75 of the first lens array means 71 is 
incident upon the second lens array means 72, it enters nine microlens 
elements 76, the number of the microlens elements is not limited to nine, 
but may be increased, for example, to twenty-five, forty-nine and so on, 
and in any case, it is desirable that the equation (5) ia satisfied. 
According to the present invention, even in the case where the distance 
from the incident side face of the light valve to the light valve layer 
can not be shortened, by employing the two lens array means as shown in 
the model of FIG. 1, or three lens array means as shown in the model of 
FIG. 3, the light valve apparatus with a high substantial aperture ratio 
can be realized. When this light valve apparatus is employed for a 
projection display system, bright projection images may be obtained. 
Moreover, if the light valve apparatus of the present invention is used 
for a view-finder system, bright display images can also be obtained. 
It is to be noted here that in the foregoing embodiments, although 
description given with respect to the case where the pixels of the light 
valve are arranged in the square shape, and the optical axis of each of 
the microlens elements for the first lens array means is aligned with that 
of each of the microlens elements for the second lens array means, and 
also, with that of each of the microlens elements for the third lens array 
means, the present invention is not limited in its application to the 
above case alone, but the intended effect of the present invention may be 
obtained even in the case where the pixels of the light valve are arranged 
for example, in a delta form or the relation of the optical axis is 
different from the above case, if the second very small light source group 
by each of the microlens elements for the second lens array means is 
entirely overlapped. 
Referring now to the drawings, embodiments according to the present 
invention will be described. 
There is shown in FIG. 8, the construction of a light valve apparatus 
according to a first embodiment of the present invention. 
In FIG. 8, the light valve apparatus of the present invention generally 
includes an incident side polarizing plate 101, a first lens array plate 
102, a second lens array plate 103, a liquid crystal panel 104, and an 
emitting side polarizing plate 105 sequentially arranged in that order 
from the incident side as shown. 
The liquid crystal panel 104 further includes two glass substrates 106 and 
107, and TN liquid crystal layer 108 enclosed between said glass 
substrates for being sealed. At the side of the liquid crystal layer 108 
of the emitting side glass substrate 107, pixel electrodes are formed by 
transparent conductive films in a matrix pattern, and in the vicinity of 
each of the pixel electrodes, TFT 110 is provided as a switching element. 
Between the neighboring pixel electrodes, signal lines and scanning lines 
are formed, and in each of the TFT 110, the source electrode is connected 
to the signal line, the gate electrode, to the scanning line, and the 
drain electrode, to the pixel electrode. At the side of the liquid crystal 
108 of the incident side glass substrate 106, a common electrode is formed 
by the transparent conductive film, and black matrix 112 of a metallic 
thin film are formed thereon so as to cover the TFT 110, signal lines and 
scanning lines. The opening portion of the black matrixes 112 serve as the 
pixels 113. Onto the pixel electrodes and the common electrode, an 
alignment film is applied, and rubbing is effected for orientating the 
liquid crystal molecules in the predetermined state. 
Upon impression of an electric filed to the liquid crystal layer of each of 
the pixels 113 by the signal feeding circuit and scanning circuit, the 
rotatory polarization of the liquid crystal layer is varied according to 
the electric field and, an optical image as the variation of the rotatory 
polarization corresponding to the video signals can be formed on the 
liquid crystal panel 104. This optical image will become an optical image 
based on the variation of transmittance by the action of the incident side 
polarizing plate 101 and the emitting side polarizing plate 105. 
The number of the pixels for the liquid crystal panel 104 is 480 
horizontally.times.460 vertically, the dimension of the display screen are 
44.64 mm horizontally.times.33.58 mm vertically, and the pixel pitch is 94 
.mu.m horizontally.times.73 .mu.m vertically. As shown in FIG. 9, the 
pixels 113 are arranged in the square form, with the size of the pixel 
being 53 .mu.m horizontally.times.32 .mu.m vertically, and aperture ratio 
at 25%. Each of the two glass substrates 106, and 107 has a thickness of 
1.1 mm and refractive index of 1.52. 
The first lens array plate 102 is prepared by overlapping a thin 
transparent resin 115 on the emitting side face of the glass substrate 
114, and a plurality of microlens elements 116 are formed in the matrix 
pattern on the surface thereof, while the second lens array plate 103 is 
prepared by also overlapping a thin transparent resin 118 on the emitting 
side face of the glass substrate 117, and a plurality of microlens 
elements 119 are formed in the matrix pattern on the surface thereof. The 
microlens elements 116 and 119 are respectively arranged in the square 
shape as shown in FIG. 9, and have effective regions in the rectangular 
shape, and arrangement pitch of 94 .mu.m horizontally.times.73 .mu.m 
vertically similar to the pixel pitch of the liquid crystal panel 104, 
with non-lens portions 120 and 121 of about 5 .mu.m in width being 
provided between the neighboring microlens elements as shown. The first 
lens array plate 102 has the thickness of its glass substrate 114 at 1.1 
mm, refractive index of 1.52 and a focal length of 240 .mu.m. The second 
lens array plate 103 has the thickness of its glass substrate 117 at 1.4 
mm, refractive index of 1.52, and a focal length of 360 .mu.m. The two 
lens array plates 102 and 103 are prepared in such a manner that an 
ultraviolet curing resin is applied over the glass plates 114 and 117, and 
molds having the surface shape of the predetermined lens array plates are 
overlapped thereon for irradiation of ultraviolet rays onto the 
ultraviolet curing resin through the glass plates 114 and 117. 
The first lens array plate 102, the second lens array plate 103, and the 
liquid crystal panel 104 are so overlapped that the optical axis 122 of 
each of the microlens elements 116 for the first lens array plate 102 is 
aligned with the optical axis 123 of each of the microlens elements 119 of 
the second lens array plate 103, and the optical axes 122 and 123 pass 
through the center 124 of each of the pixels 113 for the liquid crystal 
panel 104, with a peripheral portion being fixed by a bonding agent 
through thin air layers provided between the lens array plates 102 and 103 
and the liquid crystal panel 104. The incident side polarizing plate 101 
is separated from the first lens array plate 102, and the emitting side 
polarizing plate 105 is applied to the emitting side of the liquid crystal 
panel 104. 
Hereinafter, a first embodiment of a projection display system of the 
present invention will be explained with reference to FIG. 10 showing the 
general construction thereof. 
In FIG. 10, the projection display system generally includes a light source 
131, a field lens 135, a light valve apparatus 136, a projection lens 
assembly 137 having an auxiliary projection lens 139 and a main projection 
lens 140, and a projection screen 138. 
The light valve apparatus 136 is similar to that as shown in FIGS. 8 and 9, 
and includes the incident side polarizing plate 101, first lens array 
plate 102, second lens array plate 103, liquid crystal panel 104, and 
emitting side polarizing plate 105 sequentially disposed from the incident 
side. 
The light source 131 further includes a lamp 132, a concave mirror 133, and 
a filter 134. Light emitted from the lamp 132 which is a halogen lamp, is 
reflected by the concave mirror 133 and emitted in the form close to 
parallel light rays. The filter 134 constituted by a glass substrate on 
which multi-layered films transmitting visible light and reflecting 
infrared rays are deposited, eliminates infrared rays from the light 
emitted from the concave mirror 133. 
Light emitted from the light source 131 passes through the field lens 135 
so as to be incident on the light valve apparatus 136, and light outgoing 
therefrom is incident upon the projection lens assembly 137. Thus, the 
images formed on the liquid crystal panel 104 are magnified and projected 
onto the projection screen 138 by the projection lens assembly 137. The 
field lens 135 is used for directing light incident upon the pixels around 
the liquid crystal panel 104 from the light source 131, to be 
perpendicular to the liquid crystal layer 108 (FIG. 8). The projection 
lens assembly 137 constituted by the auxiliary lens 139 disposed at the 
emitting side of the liquid crystal panel 104 and the main projection lens 
140, has an aperture ratio of F3.5. The auxiliary lens 139 has for its 
object to make the principal light rays transmitted through all the pixels 
of the liquid crystal panel 104, perpendicular to the liquid crystal layer 
108. Thus, light advancing along the optical axis 122 of the microlens 
element 116 of the first lens array plate 102 passes through the optical 
axis 123 of the corresponding microlens element 119 of the second lens 
array plate 103, and is incident upon the center 124 of the corresponding 
pixel 113 of the liquid crystal panel 104. 
Subsequently, functions of the arrangement as shown in FIGS. 8 and 9 will 
be described. 
Referring back to FIG. 8, light rays 125 emitted from the light source 131 
(FIG. 10) are incident on the first lens array plate 102. On the focal 
point 126 of each of the microlens elements 116 of the first lens array 
plate 102, a very small real image corresponding to the opening portion of 
the concave mirror 133 is formed. The respective microlens elements 119 of 
the second lens array plate 103 form the plurality of very small light 
sources on the liquid crystal layer 108 of the liquid crystal panel 104 at 
an equal size. The focal length f.sub.1 of the microlens element 116 for 
the first lens array plate 102, and the focal length f.sub.2 of the 
microlens element 119 for the second lens array plate 103 are adapted to 
satisfy the conditions of the equation (5) referred to earlier. Therefore, 
light emitted from one microlens element 116a for the first lens array 
plate 102 is incident on nine microlens elements 119a, 119b and 119c for 
the second lens array plate 103, and light rays emitted from the nine 
microlens elements 119a, 119b and 119c are respectively incident upon the 
pixels, 113a, 113b and 113c of the liquid crystal panel 104. On one pixel 
113d of the liquid crystal panel 104, incident light rays from neighboring 
nine microlens elements 119d, 119e and 119f of the second lens array plate 
103 are incident. It is so arranged that light rays emitted from the 
liquid crystal panel 104 are all incident on the projection lens assembly 
137. On the light valve apparatus 136, optical images are formed as the 
variation of the transmittance according to the video signals. Such 
optical images are magnified and projected by the projection lens assembly 
137, whereby enlarged projection images in black and white are displayed 
on the projection screen. 
In the case where light rays emitted from the light source 131 and incident 
upon one microlens element 116 for the first lens array 102 are all 
incident upon the projection lens 137, and substantial aperture ratio of 
the light valve apparatus 136 may be represented by a ratio of areas on 
the lens face of all the microlens elements, to the area for the all 
region of the first lens array plate 102. The brightness at the image 
center of the projected image is increased by a ratio of the substantial 
aperture ratio, with respect to the actual aperture ratio of the liquid 
crystal panel. 
Upon experiments carried out by combining the two lens array plates 102 and 
103, brightness near the central portion of the projected image can be 
increased by 1.5 times that in the case where the lens array plate was not 
used, and thus, the effectiveness of the present invention could be 
ensured. It is to be noted here that, upon consideration that the aperture 
ratio of the liquid crystal panel 104 is 25%, and substantial aperture 
ratio of the lens array plates 102 and 103 neglecting the Surface 
reflection is theoretically 65%, the effect of the brightness improvement 
is considerably lower than the theoretical value, but this may be 
attributable to insufficient accuracy on the lens surfaces of said lens 
array plates 102 and 103. 
Although in the conventional arrangement referred to earlier in FIG. 25, it 
was necessary to make the incident side glass substrate of the liquid 
crystal panel thin in order to increase the brightness of the projected 
images, in the arrangement of the present invention as shown in FIG. 8, it 
is possible to improve the brightness of the projected image without 
thinning the incident side glass substrate 106 of the liquid crystal panel 
104. Thus, since it is not necessary to reduce the thickness of the 
incident side glass substrate 106, uniformity in the thickness of the 
liquid crystal layer 108 can be maintained, and images at high quality may 
be displayed on the liquid crystal panel 104. Accordingly, by adopting the 
arrangement as shown in FIG. 8, projected images at high image quality can 
be obtained with sufficient brightness. 
FIG. 11 shows a projection display system according to a second embodiment 
of the present invention. 
In FIG. 11, a light source 151 includes a lamp 152, a concave mirror 153, 
and a filter 154. The lamp 152 is of a metal halide lamp, and radiates 
light rays containing color components for three primary colors. The 
concave mirror 153 is made of glass having a reflecting face 155 in a 
parabolic form, on which a multi-layered film transmitting infrared rays 
and reflecting visible light is deposited. The filter 154 is made of a 
glass substrate on which a multi-layered film transmitting visible light 
and reflecting infrared rays and ultraviolet rays is deposited. An optical 
axis 156 of the concave mirror 153 is directed in a horizontal direction, 
and the lamp 152 is disposed with its lamp axis aligned with the optical 
axis 156. Radiation light of the lamp 152 is converted into light close to 
parallel light rays from which infrared rays are eliminated through 
reflection by the concave mirror 153, and is emitted as visible light, 
with infrared rays and ultraviolet rays being removed therefrom by being 
transmitted through the filter 154. Light emitted from the light source 
151 is separated into primary colors of red, green and blue by a color 
separation optical system constituted by two dichroic mirrors 157 and 158 
and a flat mirror 159. The respective primary colors are each transmitted 
through field lenses 160, 161 and 162 so as to be incident on light valve 
apparatuses 163, 164 and 165. 
The respective light valve apparatuses 163,164 and 165 have the 
constructions similar to those as described earlier with reference to FIG. 
8, and respectively include the incident side polarizing plates 166, 167 
and 168, first lens array plates 169, 170 and 171, second lens array 
plates 172, 173 and 174, liquid crystal panels 175, 176 and 177, and 
emitting side polarizing plates 178, 179 and 180 as combined sequentially 
from the side of the light source. On each of the light valve apparatuses 
163, 164 and 165, an optical image as variation of transmittance is formed 
according to the video signals respectively. Light rays emitted from the 
light valve apparatuses 163, 164 and 165 are composed into one light ray 
by a color combining optical system in which dichroic mirrors 184 and 185 
and a flat mirror 186 are combined, after having been transmitted through 
auxiliary lenses 181, 182 and 183 respectively, and the composed light is 
incident upon a main projection lens 187. 
The main projection lens 187 functions as a projection lens by being 
combined with the auxiliary lenses 181, 182 and 183, which are employed to 
allow the principal light rays of the projection lens 187 to pass through 
the liquid crystal layer perpendicularly, i.e., to improve so-called 
"telecentric" characteristic. Thus, the optical images formed on the three 
light valve apparatuses 163, 164 and 165 are magnified and projected by 
the main projection lens 187 onto a projection screen (not shown) located 
at a distant position. 
Upon experiments carried out on the projection display apparatus as shown 
in FIG. 11 trially produced, projection images brighter than those in the 
case where the lens array plates were not employed, could be obtained. The 
uniformity of the image quality was also favorable except for faulty 
portions clearly attributable to the light valve apparatuses. 
FIG. 12 shows a light valve apparatus according to a second embodiment of 
the present invention, which generally includes an incidence side 
polarizing plate 201, a lens array plate 202, a liquid crystal panel 203, 
and an emitting side polarizing plate 204 sequentially disposed in that 
order from the incident side. 
The liquid crystal panel 203 is of a TFT liquid crystal panel employing the 
TN liquid crystal similar to that described earlier with reference to FIG. 
8, and has a pixel arrangement as shown in FIG. 13. At the side of the 
liquid crystal layer 206 of the emitting side glass substrate 205, there 
are provided pixel electrodes 207 and TFT 208. Meanwhile, at the side, of 
the liquid crystal 206 of the incident side glass substrate 209, black 
matrix 210 is provided to shield the TFT against light, on which black 
matrix 210, a color filter 21 in a mosaic pattern is disposed, with a 
common electrode being further provided thereon. 
The number of pixels for the liquid crystal panel 203 is 480 
horizontally.times.460 vertically, the dimensions of the display screen 
are 30.7 mm horizontally.times.23.0 mm vertically, and the pixel pitch is 
64 .mu.m horizontally.times.50 .mu.m vertically. The size of the pixel is 
33 .mu.m horizontally.times.29 .mu.m vertically, and aperture ratio at 
25%. The incident side glass substrate has a thickness of 1.1 mm and 
refractive index of 1.52. 
The lens array plate 202 has a first lens array 213 formed on an incident 
side face of a glass substrate 212, and a second lens array 214 formed on 
an emitting side face thereof. The first lens array 213 and the second 
lens array 214 are respectively prepared by overlapping thin transparent 
layers 215 and 216 on the glass substrate 212, and forming convex lens 
surfaces 217 and 218thereon. As shown in FIG. 13, each of the microlens 
elements 217 and 218 has an effective region in a hexagonal shape, and 
these lens elements 217 and 218 are arranged in a delta form at a pitch 
equal to that of the liquid crystal panel 203, with non-lens portions 219 
and 220 of 5 .mu.m in width being provided between the neighboring 
microlens elements as shown. The optical axis 221 of each of the microlens 
elements 217 is aligned with the optical axis 222 of the corresponding 
microlens element 218. The glass substrate 212 has thickness of 1.4 mm and 
refractive index of 1.52, and the focal length of the first lens array 213 
is 240 .mu.m, and that of the second lens array 214 is 360 .mu.m. 
The lens array plate 202 and the incident side glass substrate 209 of the 
liquid crystal panel 203 are bonded at the peripheral edge portion 
thereof, with a thin air layer being held therebetween. In this case, it 
is so arranged that the optical axes 221 and 222 of the respective 
microlens elements 217 and 218 for the lens array plate 202 pass through 
the centers 224 of the corresponding pixels 223 of the liquid crystal 
panel 203. The arrangement as shown in FIG. 12 provides better 
transmittance, since the boundary face having a difference in the 
refractive index is smaller than in the arrangement which employs two lens 
array plates. 
In the above case also, the image of an imaginary object located on the 
focal point 225 of the microlens element 217 for the first lens array 213 
is formed on the pixel 223 of the liquid crystal panel 203 by the second 
lens array 214. Light emitted from one microlens element 217 of the first 
lens array 213 is incident upon seven normal lens elements 218 for the 
second lens array 214, and light emitted from the seven microlens elements 
for the second lens array 214 is incident on one pixel 223 of the liquid 
crystal panel 203. Thus, in the similar manner as in the previous 
embodiment, the substantial aperture ratio may be improved by the lens 
array plate 202. 
When the light valve apparatus for the projection display system described 
earlier with reference to FIG. 10 is replaced by the light valve apparatus 
of FIG. 12, a projection image in full color can be obtained. As a result 
of experiments, brightness in the vicinity of the central portion of the 
projected image became about 1.5 times that in the case where the lens 
array plate was not provided. 
Subsequently, an embodiment in which the light valve apparatus of the 
present invention has been applied to a view-finder system will be 
explained with reference to FIG. 14. 
In FIG. 14, the view-finder system generally includes a casing 240, and a 
light valve apparatus 231, light source 236, and an eye-piece 239 which 
are accommodated in said casing 240 as described hereinbelow. 
Although different in the dimensions of respective parts, the light valve 
apparatus 231 has the construction similar to that described earlier with 
reference to FIG. 12, and is constituted by an incident side polarizing 
plate 232, a lens array plate 233, a liquid crystal panel 234, and an 
emitting side polarizing plate 235 sequentially disposed in that order 
from the incident side. The liquid crystal panel 234 is of a TFT liquid 
crystal panel employing the TN liquid crystal similar to that described 
earlier with reference to FIG. 12, and incorporated with a color filter in 
a mosaic form. The display size is of 0.7 inch, and an image in full color 
is displayed. 
The number of pixels for the liquid crystal panel 234 is 372 
horizontally.times.238 vertically, and the pixel pitch is 38 .mu.m 
horizontally.times.44 .mu.m vertically. The size of the pixel is 18 .mu.m 
horizontally.times.24 .mu.m vertically, with aperture ratio at 25%. Each 
of the glass substrates for the liquid crystal panel has a thickness of 
1.1 mm and refractive index of 1.52. The lens array substrate has a 
thickness of 1.3 mm, and the focal length of the first lens array is 100 
.mu.m, and that of the second lens array is 360 .mu.m. 
The light source 236 is constituted by a lamp 237 and a condenser lens 238. 
The lamp 237 is of a fluorescent lamp with a diameter of 7 mm and a length 
of 20 mm to be turned on by D.C., and light irradiated from the lamp 237 
is converted into a light ray with a narrow directivity by the condenser 
lens 238 so as to be incident upon the light valve apparatus 231, and 
light emitting therefrom is further incident on the eye-piece 239. When an 
observer (not shown) looks into the eye-piece 239, a magnified virtual 
image of the image on the light valve apparatus 231 can be seen. For the 
lamp 237, a light source of a high brightness with a small light emitting 
member such as an LED, halogen lamp, cathode ray tube or the like may be 
employed. 
In the view-finder system as shown in FIG. 14, by employing the lens array, 
the substantial aperture ratio of the light valve apparatus is increased, 
and consequently, light utilizing efficiency can also be raised. 
Accordingly, power consumption of the lamp may be reduced, and the 
continuous using time in one charging of a battery is prolonged as 
compared with the case where the lens array is not employed. 
Reference is made to FIG. 15 showing the construction of a light valve 
apparatus according to a third embodiment of the present invention. 
In FIG. 15, the light valve apparatus of the present invention generally 
includes an incident side polarizing plate 301, a first lens array plate 
307, second lens array plate 308, a liquid crystal panel 305, and an 
emitting side polarizing plate 306 sequentially arranged in that order 
from the incident side as shown. 
The liquid crystal panel 305 has the construction similar to that described 
earlier with reference to FIG. 8. 
The first lens array plate 307 is prepared by overlapping a thin 
transparent resin 316 on the emitting side face of the glass substrate 
315, and a plurality of microlens elements 316 are formed in the matrix 
pattern on the surface thereof, while the second lens array plate 308 is 
prepared also by overlapping a thin transparent resin 319, and 320 on the 
emitting side face and incident side face of the glass substrate 318, and 
a plurality of microlens elements 321 and 322 are formed in the matrix 
pattern on the surface thereof. The microlens elements 317, 321 and 322 
are respectively arranged in the square shape as shown in FIG. 16, and 
have effective area in the rectangular shape, and arrangement pitch of 94 
.mu.m horizontally.times.73 .mu.m vertically similar to the pixel pitch of 
the liquid crystal panel 305, with non-lens portions 323, 324 and 325 of 
about 5 .mu.m in width being provided between the neighboring microlens 
elements as shown. The first lens array plate 307 has the thickness of its 
glass substrate 315 at 1.1 mm, refractive index of 1.52 and a focal length 
of each of the microlens elements 317 of the first lens array 302 at 240 
.mu.m. The second lens array plate 308 has the thickness of its glass 
substrate 318 at 1.1 mm, refractive index of 1.52, and a focal distance of 
each of the microlens elements 321 of the second lens array 303 at 360 
.mu.m. The focal length of each of the microlens elements 322 for the 
third lens array 304 is 120 .mu.m. The three lens arrays 302, 303 and 304 
are each prepared in such a manner that an ultraviolet curing resin is 
applied over the glass substrates 315 and 318, and molds having the 
surface shape of the predetermined lens array plates are overlapped 
thereon for irradiation of ultraviolet rays onto the ultraviolet curing 
resin through the glass substrates 315 and 318. 
The first lens array 302, the second lens array 303, the third lens array 
304 and the liquid crystal panel 205 are so disposed that the optical axis 
326 of each of the microlens elements 317 for the first lens array 302, 
the optical axis 327 of each of the microlens elements 327 for the third 
lens array 304, and the optical axis 328 of each of the microlens elements 
321 of the second lens array 303 are aligned, and the optical axes 326, 
327 and 328 pass through the center 329 of each of the pixels 314 for the 
liquid crystal panel 305, with the peripheral portion being fixed by an 
bonding agent through thin air layers provided between the incident side 
glass substrate 309 of the liquid crystal panel 305 and the second lens 
array plate 308. The first lens array plate 307 and the second lens array 
plate 308 are provided with a spacer of 0.32 mm at edge potions, which are 
fixed by a bonding agent. The incident side polarizing plate 301 is 
separated from the first lens array plate 307, and the emitting side 
polarizing plate 306 is applied to the emitting side of the liquid crystal 
panel 305. 
When the light valve apparatus of the projection display system referred to 
earlier with reference to FIG. 10 is replaced by the light valve apparatus 
as shown in FIG. 15, projection images may be obtained. 
Subsequently, functions of the arrangement as shown in FIGS. 15 and 16 will 
be described. 
As shown in FIG. 15, light rays 330 emitted from the light source are 
incident on the first lens array plate 302. On the focal point 331 of each 
of the microlens elements 317 of the first lens array plate 302, a very 
small real image corresponding to the opening of the concave mirror of the 
light source is formed. The respective microlens elements 321 of the 
second lens array plate 303 form the plurality of very small light sources 
on the liquid crystal layer 311 of the liquid crystal panel 305 at an 
equal size. The focal length f.sub.1 of the microlens element 317 for the 
first lens array plate 302, and the focal length f.sub.2 of the lens 
element 321 for the second lens array plate 303 are adapted to satisfy the 
conditions of the equation (5) referred to earlier. Therefore, light 
emitted from one lens element 317a for the first lens array plate 302 is 
incident on nine lens elements 321a, 321b and 321c for the second lens 
array plate 303, and light rays emitted form the nine lens elements 321a, 
321b and 321c are respectively incident upon the pixels 314a, 314b and 
314c of the liquid crystal panel 305. On one pixel 314d of the liquid 
crystal panel 305, incident light rays from neighboring nine microlens 
elements 321d, 321e and 321f of the second lens array plate 303 are 
incident. It is so arranged that light rays emitted from the liquid 
crystal panel 305 are all incident on the projection lens. On the light 
valve apparatus, optical images are formed as the variation of the 
transmittance according to the video signals. Such optical images are 
magnified and projected by the projection lens assembly, whereby enlarged 
projection images in black and white are displayed on the projection 
screen. 
In the case where light rays emitted from the light source and incident 
upon one lens element 317 for the first lens array 302 are all incident 
upon the projection lens, substantial aperture ratio of the light valve 
apparatus may be represented by a ratio of areas on the lens face of all 
the microlens elements, to the area for the all region of the first lens 
array plate 302. The brightness at the image center of the projected image 
is increased by a ratio of the substantial aperture ratio, with respect to 
the actual aperture ratio of the liquid crystal panel. Furthermore, high 
quality image may be displayed on the projection screen, since it is not 
necessary to reduce the thickness of the incident side glass substrate 309 
of the liquid crystal panel 305, as the same case of FIG. 8. 
Upon experiments carried out by combining the two lens array plates 307 and 
308, brightness near the central portion of the projected image can be 
increased in comparison with the case where the lens array plate was not 
used, and thus, the effectiveness of the present invention could be 
ensured. 
Projected image in full color may also be obtained when the light valve 
apparatus for the projection display system in FIG. 11 is replaced by the 
light valve apparatus of FIG. 15. In this case, projected images brighter 
than those in the case where two lens array plates are not employed, could 
be obtained. 
In FIG. 17, there is shown the construction of a light valve apparatus 
according to a fourth embodiment of the present invention. 
In FIG. 17, the light valve apparatus of the present invention generally 
includes an incident side polarizing plate 351, a first lens array plate 
352, a second lens array plate 353, a liquid crystal panel 354, and an 
emitting side polarizing plate 355 sequentially arranged in that order 
from the incident side as shown. The liquid crystal panel 354 is similar 
in construction, to that described earlier with reference to FIG. 12. 
The first lens array plate 352 has a first lens array 357 formed on an 
emitting side face of a glass substrate 356, and a second lens array plate 
353 has a third lens array 359 formed on an incident side face of a glass 
substrate 358. The second lens array 360 is formed on an incident side 
face of an incident side glass substrate 361 of the liquid crystal panel 
354. The first lens array 357 and the third lens array 359 are 
respectively prepared by overlapping thin transparent layers 362 and 363 
on the glass substrates 356 and 358, and forming convex lens surfaces 364 
and 365 thereon. The second lens array 360 is prepared by overlapping a 
thin transparent resin 366 on the incident side glass substrate 361, and 
forming convex lens surfaces 367 thereon. As shown in FIG. 18, each of the 
microlens elements 364, 365, and 367 has an effective region in a 
hexagonal shape, and these lens elements 363, 364, and 366 are arranged in 
a delta form at a pitch equal to that of the liquid crystal panel 354, 
with non-lens portions 368, 369 and 370 of 5 .mu.m in width being provided 
between the neighboring microlens elements as shown. The optical axis 377 
of each of the microlens elements 364 of the first lens array 357 is 
aligned with the optical axis 378 of the corresponding microlens elements 
365 of the third lens array 359, and also, with the optical axis 379 of 
each of the microlens elements 367 of the second lens array 360. 
Each of the glass substrates 356 and 358 has a thickness of 1.1 mm and 
refractive index of 1.52, and the focal length of the first lens array 357 
is 240 .mu.m, that of the second lens array 360 is 360 .mu.m, and that of 
the third lens array 359 is 120 .mu.m. 
The second lens array plate 353 and the incident side glass substrate 361 
of the liquid crystal panel 354 are bonded by a bonding agent at the 
peripheral edge portion thereof, with a thin air layer being held 
therebetween. The second lens array plate 353 and the first lens array 
plate 352 are provided with a spacer of 0.35 mm in thickness around 
peripheral portions thereof for fixing by a bonding agent. In this case, 
it is so arranged that the optical axis 377 of each of the microlens 
elements 364 for the first lens array 357 is aligned with the optical axis 
378 of each of the microlens elements 365 for the third lens array 359, 
and further, with the optical axis 379 of each of the microlens elements 
367 of the second lens array 360, with the optical axes 377, 378 and 379 
passing through centers 381 of the corresponding pixels 380 of the liquid 
crystal panel 354. 
In the above case also, the image of an imaginary object located on the 
focal point 382 of the microlens elements 364 for the first lens array 357 
is formed on the pixel 380 of the liquid crystal panel 354 by the second 
lens array 360. Light emitted from one microlens element 364 of the first 
lens array 357 is incident upon seven microlens elements 366 for the 
second lens array 360, and light emitted from the seven microlens elements 
for the second lens array 360 is incident on one pixel 380 of the liquid 
crystal panel 354. Moreover, light rays passing through the edge portion 
of the very small light sources formed by the respective microlens 
elements 364 for the first lens array 357 are also incident upon the 
respective corresponding microlens elements 367 for the second lens array 
360 by the respective microlens elements 365 for the third lens array 359, 
whereby utilization efficiency of the light rays is improved, and brighter 
projection images can be obtained. Thus, in the similar manner as in the 
previous embodiment, the substantial aperture ratio may be improved by the 
three sets of the lens arrays 357, 359 and 360. 
When the light valve apparatus for the projection display system described 
earlier with reference to FIG. 10 is replaced by the light valve apparatus 
of FIG. 17, a projection image in full color can be obtained. 
Hereinbelow, a further embodiment in which the light valve apparatus of the 
present invention has been applied to the view-finder system will be 
described with reference to FIG. 14. Although different in the dimensions 
of each parts, the light valve apparatus generally has the construction 
similar to that in FIG. 17, and includes the incident side polarizing 
plate 351, the first lens array plate 352, the second lens array plate 
353, a liquid crystal panel 354, and an emitting side polarizing plate 355 
sequentially arranged in that order from the incident side as shown 
(indicated by numerals in parentheses). The liquid crystal panel 354 is 
similar to that of the light valve apparatus described earlier with 
reference to FIG. 14. 
Each of the glass substrates for the lens array plates has a thickness of 
1.1 mm and refractive index of 1.52, and the focal length of the first 
lens array is 240 .mu.m, that of the second lens array is 360 .mu.m, and 
that of the third lens array is 120 .mu.m. 
In the case where the light valve apparatus of the view finder system as 
shown in FIG. 14, is replaced by the above light valve apparatus, 
magnified images in full color may be observed. 
In the view-finder system, since the substantial aperture ratio is 
increased by the employment of the lens array, the light utilizing 
efficiency can be raised, and consequently, power consumption for the lamp 
can be decreased, and as compared with the case where the lens array is 
not employed, continuous using time by one charging of the battery can be 
prolonged. 
Subsequently, other embodiments of the light valve apparatus according to 
the present invention will be described. 
In FIGS. 8 and 12, although there has been shown the arrangement in which 
the optical axis of each of the microlens elements for the first lens 
array is aligned with the optical axis of each of the corresponding 
microlens elements for the second lens array, it is possible to adopt the 
arrangements other than the above. 
By way of example, a shown in FIG. 19(a), it may be so arranged that an 
optical axis 403 of the microlens element 402 for a first lens array 401 
passes through a center point 407 of a straight line connecting centers 
406a and 406b of neighboring two microlens elements 405a and 405b for a 
second lens array 404. However, in this case, the optical axis 403 is 
required to pass through the pixel 409 of the liquid crystal panel 408. 
In the case where the pixels of the liquid crystal panel are of the delta 
disposition, the arrangement may be so made as shown in FIG. 19(b) that an 
optical axis 413 of the microlens element 412 for a first lens array 411 
passes through a center point 417 of a straight line connecting centers 
416a and 416b of neighboring two microlens elements 415a and 415b for a 
second lens array 414 and also passes through the pixel 419 of the liquid 
crystal panel 418. 
In the case where the pixels of the liquid crystal panel are of the square 
disposition, it may be so arranged as shown in FIG. 20(a) that an optical 
axis 423 of the microlens element 422 for a first lens array 421 passes 
through a center 427 of a rectangle 426 formed by lines, connecting 
centers of neighboring four microlens elements 425a, 425b, 425c, and 425d 
of the second lens array 424, and also, through the pixel 429 of the 
liquid crystal panel 428. 
Meanwhile, in the case of the delta disposition, such arrangement as shown 
in FIG. 20(b) may be adopted in which an optical axis 432 of the microlens 
element 431 for a first lens array 430 passes through an outer center 437 
of a triangle 436 constituted by lines connecting centers of neighboring 
three microlens elements 435a, 435b and 435c for the second lens array 
433, and also, passes through a center point 441 of a line connecting 
centers 440a and 440b of the pixels 439a and 439b of the liquid crystal 
panel 438. In any of the above case, by the second lens array, the real 
image of the very small light source formed on the focal point of each of 
the microlens element for the first lens array can be formed on each of 
the pixels of the liquid crystal panel. 
In FIGS. 15 and 17, although there has been shown the arrangement in which 
the optical axis of each of the microlens elements for the first lens 
array is aligned with the optical axes of the corresponding microlens 
elements for the second and third lens arrays, it is possible to adopt the 
arrangements other than the above. 
By way of example, as shown in FIG. 21(a), it may be so arranged that an 
optical axis 453 of the microlens element 452 for a first lens array 451 
is aligned with an optical axis 456 of the microlens element 455 for the 
third lens array 454 and passes through a center point 460 of a straight 
line connecting centers 459a and 459b of neighboring two lens elements 
458a and 458b of the second lens array 457. However, in this case, the 
optical axis 453 is required to pass through the pixel 562 of the liquid 
crystal panel 461. Also, in the case where the pixels of the liquid 
crystal panel are of the delta disposition, the arrangement may be so made 
as shown in FIG. 21(b) that an optical axis 468 of the microlens element 
467 for a first lens array 466 is aligned with an optical axis 471 of the 
microlens element 470 of the third lens array 469 and passes through a 
center point 475 of a straight line connecting centers 474a and 474b of 
neighboring two microlens elements 473a and 473b of the second lens array 
472, and also passes through the pixels 477 of the liquid crystal panel 
476. 
In the case where the pixels of the liquid crystal panel are of the square 
disposition, it may be so arranged as shown in FIG. 22(a) that an optical 
axis 483 of the microlens element 482 for a first lens array 481 is 
aligned with an optical axis 486 of the lens element 485 for the third 
lens array 484, and passes through the center 491 of a rectangle formed by 
lines connecting centers of the neighboring four microlens elements 488a, 
488b, 488c and 488d of the second lens array 487, and also passes through 
the center 494 of the pixel 493 of the liquid crystal panel 492. 
Meanwhile, in the case of the delta disposition, such arrangement as shown 
in FIG. 22(b) may be adopted in which an optical axis 498 of the microlens 
element 497 for a first lens array 496 is aligned with an optical axis 501 
of each of the lens element 500 of a third lens array 499, and further 
passes through an outer center 505 of a triangle 504 constituted by lines 
connecting centers of neighboring three microlens elements 503a, 503b, and 
503c for the second lens array 502, and also, passes through a center 
point 509 of a line connecting centers 508a and 508b of the pixels 507a 
and 507b for the liquid crystal panel 506. In any of the above case, by 
the second lens array, the real image of the very small light source 
formed on the focal point of each of the microlens elements for the first 
lens array can be formed on each of the pixels of the liquid crystal 
panel. 
In the case of the arrangements as shown in FIGS. 19(a), 19(b), 20(a), 
20(b), 21(a), 21(b), 22(a) and 22(b), the conditions without any wasteful 
function of the projection lens are represented by an equation as follows, 
different from the condition represented by the equation (5) referred to 
earlier. 
EQU f.sub.2 =mf.sub.1 (6) 
where f.sub.1 is a focal length of the first lens array, and f.sub.2 is a 
focal length of the second lens array. 
The lens arrays which play an important part in the light valve apparatus 
according to the present invention require supporting means, therefor. 
Besides the embodiments as described so far, there may be adopted an 
arrangement in which a glass substrate is disposed close to the incident 
side of the liquid crystal panel, and a first lens array is formed on the 
incident side face of said glass substrate, with a second lens array being 
formed on an incident side face of an incident side glass substrate of the 
liquid crystal panel. Meanwhile, in the case where a third lens array is 
to be employed, it may be, for example, so arranged that, a third glass 
substrate is disposed at an incident side glass substrate of a liquid 
crystal panel, and a second glass substrate is disposed at an incident 
side of a third glass substrate, while a first glass substrate is disposed 
at an incident side of a second glass substrate, and a first lens array is 
formed at an emitting side face of the first glass substrate, and a third 
lens array is formed on an emitting side face of the second glass 
substrate, with a second lens array being formed on the emitting side face 
of the third glass substrate. Moreover, it is also possible to employ an 
arrangement in which a second lens array is formed at an incident side 
face of an incident side glass substrate of liquid crystal panel, and a 
second glass substrate is disposed at an incident side of a second lens 
array, while a first glass substrate is disposed at an incident side of a 
second glass substrate, while a third lens array is formed at an incident 
side of a second glass substrate, and a first lens array is formed at any 
of the incident side or emitting side face of the first glass substrate. 
Similarly, another arrangement which may be employed is such that a second 
glass substrate is disposed at an incident side of an incident side glass 
substrate of a liquid crystal panel, and a first glass substrate is 
disposed at an incident side of a second glass substrate, while a first 
lens array is formed on an incident side face of the first glass 
substrate, with a third lens array formed on an emitting side face 
thereof, and a second lens array is formed on an emitting side face of the 
second glass substrate. Moveover, it may be so arranged that a second lens 
array is formed on an incident side face of an incident side glass 
substrate of the liquid crystal panel, and a glass substrate is disposed 
at an incident side of the second lens array, while a first lens array is 
formed on the incident side face of the glass substrate, and the third 
lens array is formed on the emitting side face thereof. 
The pitch of the microlens elements for the first lens array may be made 
slightly larger than that of the pixels for the liquid crystal panel. When 
the pitches and disposition of the second lens array and the third lens 
array are properly selected by a simple drawing of an optical path 
diagram, it will be seen that the real images of the very small light 
sources formed on the focal points of the respective lens elements for the 
first lens array can be formed on the pixels of the liquid crystal panel 
by the second lens array through reduction of loss by the microlens 
elements for the third lens array. By such an arrangement, since principal 
light rays passing through the pixels at the peripheral portions of the 
liquid crystal panel can be directed inwards, an auxiliary lens 139 
employed in the arrangement as shown in FIG. 10 may be dispensed with. 
In the liquid crystal panel employing the TN liquid crystal, favorable 
contrast may be obtained in a direction slightly inclined from a normal 
line of the liquid crystal layer, and therefore, in order to obtain a 
projection image at high contrast, it may be so arranged to direct light 
to be incident upon the liquid crystal panel slantwise. In this case, the 
arrangement may be so made as to subject the microlens element group for 
the first lens array, that for the second lens array, and that for the 
third lens array, to slight parallel displacement with respect to the 
liquid crystal panel, so that the real images of the very small-light 
sources to be formed on the respective focal points of the first lens 
array are formed on the respective pixels of the liquid crystal panel. 
In both of the light valve apparatus and the light valve, besides the 
manufacturing method of the lens array plates as described earlier with 
reference to the first embodiment, there has been conventionally proposed 
a method in which refractive index distribution lens is formed on the 
surface of a glass substrate by the ion exchange, selective diffusion or 
the like as disclosed, for example, in Japanese Patent Laid-Open 
Publication Tokkaihei No. 2-302726 or a method in which transparent 
thermoplastic resin is overlapped on a glass substrate for forming lenses 
by heat molding. 
It is to be noted here that in the foregoing embodiments, although the TFT 
liquid crystal panel using TN liquid crystal has been described as used 
for the light valve, liquid crystal panels of other systems or panels 
using electro-optical crystals, etc. may also be used so far as they can 
form optical images as variation of optical characteristics. 
Although the present invention has been fully described by way of example 
with reference to the accompanying drawings, it is to be noted here that 
various changes and modifications will be apparent to those skilled in the 
art. Therefore, unless otherwise such changes and modifications depart 
from the scope of the present invention, they should be construed as 
included therein.