U.S. patent application number 09/036833 was filed with the patent office on 2001-06-21 for display panel and projection type display apparatus.
Invention is credited to KOYAMA, OSAMU, KUREMATSU, KATSUMI.
Application Number | 20010004251 09/036833 |
Document ID | / |
Family ID | 13495369 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010004251 |
Kind Code |
A1 |
KUREMATSU, KATSUMI ; et
al. |
June 21, 2001 |
DISPLAY PANEL AND PROJECTION TYPE DISPLAY APPARATUS
Abstract
A display panel is characterized by a pixel unit array
comprising pixel units having a combination of two of, first,
second and third three color pixels disposed in a first direction
and a combination of two color pixels differing from the
combination of the two color pixels disposed in a second direction
differing from the first direction, so as to share a color pixel,
the pixel units being two-dimensionally arranged at a predetermined
pitch on a substrate, and a microlens array comprising a plurality
of microlenses in which the pitch of the two color pixels in the
first direction and the second direction is one pitch, the
plurality of microlenses being two-dimensionally arranged on the
pixel unit array on the substrate.
Inventors: |
KUREMATSU, KATSUMI;
(HIRATSUKA-SHI, JP) ; KOYAMA, OSAMU; (TOKYO,
JP) |
Correspondence
Address: |
MORGAN & FINNEGAN
345 PARK AVENUE
NEW YORK
NY
10154
|
Family ID: |
13495369 |
Appl. No.: |
09/036833 |
Filed: |
March 9, 1998 |
Current U.S.
Class: |
345/88 ;
348/E5.141; 348/E9.027 |
Current CPC
Class: |
G02F 1/133623 20210101;
G02F 1/133621 20130101; H04N 2005/745 20130101; G02F 1/133526
20130101; H04N 9/3108 20130101; H04N 9/3155 20130101; G02F 1/134336
20130101; H04N 5/7441 20130101 |
Class at
Publication: |
345/88 |
International
Class: |
G09G 003/36 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 1997 |
JP |
9-072646 |
Claims
What is claimed is:
1. A display panel characterized by a pixel unit array comprising
pixel units having a combination of two of, first, second and third
three color pixels disposed in a first direction and a combination
of two color pixels differing from said combination of said two
color pixels disposed in a second direction differing from said
first direction, so as to share a color pixel, said pixel units
being two-dimensionally arranged at a predetermined pitch on a
substrate, and a microlens array comprising a plurality of
microlenses in which the pitch of the two color pixels in said
first direction and said second direction is one pitch, said
plurality of microlenses being two-dimensionally arranged on the
pixel unit array on said substrate.
2. A display panel characterized by a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of said first and third color pixels
disposed in a second direction differing from said first direction,
so as to share said first color pixel, said pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in said first direction and
said second direction is one pitch, said plurality of microlenses
being two-dimensionally arranged on the pixel unit array on said
substrate.
3. A display panel according to claim 1, characterized in that said
first color pixels is located at a position corresponding to the
central portion of said microlenses, said second color pixel is
located at a position corresponding to the boundary portion between
the microlenses of said microlens array in said first direction,
and said third color pixel is located at a position corresponding
to the boundary portion between the microlenses of said microlens
array in said second direction.
4. A display panel according to claim 2, characterized in that said
first color pixels is located at a position corresponding to the
central portion of said microlenses, said second color pixel is
located at a position corresponding to the boundary portion between
the microlenses of said microlens array in said first direction,
and said third color pixel is located at a position corresponding
to the boundary portion between the microlenses of said microlens
array in said second direction.
5. A display panel according to claim 1, 2, 3 or 4, characterized
in that said three color pixels comprise reflection electrodes and
are comprised of liquid crystal of a reflection display mode.
6. A display panel according to claim 1, 2, 3 or 4, characterized
in that said three color pixels comprise reflection electrodes and
use the DMD operation of the reflection electrodes.
7. A display panel according to claim 1, 2, 3 or 4, characterized
in that said three color pixels utilize liquid crystal, and two
microlens arrays in the same state of arrangement are provided at
positions symmetrical with respect to a liquid crystal layer so as
to sandwich said liquid crystal layer therebetween.
8. A projection type display apparatus characterized by a display
panel having a pixel unit array comprising pixel units having a
combination of first and second color pixels of, first, second and
third three color pixels disposed in a first direction and a
combination of said first and third color pixels disposed in a
second direction differing from said first direction, so as to
share said first color pixel, said pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in said first direction and
said second direction is one pitch, said plurality of microlenses
being two-dimensionally arranged on the pixel unit array on said
substrate, said first color pixel being located at a position
corresponding to the central portion of said microlenses,
illuminating means for causing a first color light to enter said
display panel perpendicularly thereto, causing a second color light
to enter said display panel while being inclined in said first
direction, and causing a third color light to enter said display
panel while being inclined in said second direction, and projecting
means for projecting a light beam light-modulated by said display
panel onto a predetermined surface.
9. A projection type display apparatus according to claim 8,
characterized in that light beams from the three color pixels
constituting said pixel units pass through the same microlens and
enter said projecting means.
10. A projection type display apparatus characterized by a display
panel having a pixel unit array comprising pixel units having a
combination of first and second color pixels of, first, second and
third three color pixels disposed in a first direction and a
combination of said first and third color pixels disposed in a
second direction differing from said first direction, so as to
share said first color pixel, said pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in said first direction and
said second direction is one pitch, said plurality of microlenses
being two-dimensionally arranged on the pixel unit array on said
substrate, said first color pixel being located at a position
corresponding to the central portion of said microlenses,
illuminating means for causing a first color light to enter said
display panel perpendicularly thereto, causing a second color light
to enter said display panel while being inclined in said first
direction, and causing a third color light to enter said display
panel while being inclined in said second direction, and projecting
means for projecting a light beam light-modulated by said display
panel onto a predetermined surface, the reflected lights from the
three color pixels constituting the pixel units light-modulated by
said display panel passing through the same microlens and being
directed to said projecting means.
11. A projection type display apparatus according to claim 8 or 10,
characterized in that said illuminating means color-resolves white
light from a light source into a plurality of color lights by the
use of a plurality of dichroic mirrors so that by the disposition
of said plurality of dichroic mirrors, said plurality of color
lights may be applied to said three color pixels from different
directions for the respective color lights.
12. A projection type display apparatus according to claim 8 or 10,
characterized in that said projecting means projects the
disposition surface of said microlenses or the vicinity thereof
onto a predetermined surface.
13. A direct-view type display apparatus characterized by a display
panel having a pixel unit array comprising pixel units having a
combination of first and second color pixels of, first, second and
third three color pixels disposed in a first direction and a
combination of said first and third color pixels disposed in a
second direction differing from said first direction, so as to
share said first color pixel, said pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in said first direction and
said second direction is one pitch, said plurality of microlenses
being two-dimensionally arranged on the pixel unit array on said
substrate, said first color pixel being located at a position
corresponding to the central portion of said microlenses,
illuminating means for causing a first color light to enter said
display panel perpendicularly thereto, causing a second color light
to enter said display panel while being inclined in said first
direction, and causing a third color light to enter said display
panel while being inclined in said second direction, and an
eyepiece for directing a light beam light-modulated by said display
panel to an observer's eyeball so that image information based on
said light beam may be observed.
14. A display apparatus characterized by a display panel having a
pixel unit array comprising pixel units having a combination of
first and second color pixels of, first, second and third three
color pixels disposed in a first direction and a combination of
said first and third color pixels disposed in a second direction
differing from said first direction, so as to share said first
color pixel, said pixel units being two-dimensionally arranged at a
predetermined pitch on a substrate, and a microlens array
comprising a plurality of microlenses in which the pitch of the two
color pixels in said first direction and said second direction is
one pitch, said plurality of microlenses being two-dimensionally
arranged on the pixel unit array on said substrate, said first
color pixel being located at a position corresponding to the
central position of said microlenses, and illuminating means for
causing a first color light to enter said display panel
perpendicularly thereto, causing a second color light to enter said
display panel while being inclined in said first direction, and
causing a third color light to enter said display panel while being
inclined in said second direction.
15. A display apparatus characterized by a display panel having a
pixel unit array comprising pixel units having a combination of
first and second color pixels of, first, second and third three
color pixels disposed in a direction and a combination of said
first and third color pixels disposed in a second direction
differing from said first direction, so as to share said first
color pixel, said pixel units being two-dimensionally arranged at a
predetermined pitch on a substrate, and a microlens array
comprising a plurality of microlenses in which the pitch of the two
color pixels in said first direction and said second direction is
one pitch, said plurality of microlenses being two-dimensionally
arranged on the pixel unit array on said substrate, said first
color pixel being located at a position corresponding to the
central portion of said microlenses, and illuminating means for
causing a first color light to enter said display panel
perpendicularly thereto, causing a second color light to enter said
display panel while being inclined in said first direction, and
causing a third color light to enter said display panel while being
inclined in said second direction, the emergent lights from the
three color pixels constituting the pixel units light-modulated by
said display panel being designed to pass through the same
microlens.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a display panel and a projection
type display apparatus, and is suitable, for example, for a full
color display apparatus of the single plate type for effecting the
display of a full color image by the use of a display panel with a
microlens array like a microlens array provided on the light
incidence surface of a liquid crystal display element.
[0003] 2. Related Background Art
[0004] There have heretofore been proposed various projection type
display apparatuses using a display panel with a microlens array of
this kind. For example, Japanese Laid-Open Patent Application No.
8-114780 proposes a transmission type liquid crystal display
element as a display panel with a microlens array.
[0005] FIG. 13 of the accompanying drawings is a cross-sectional
view of the essential portions of a liquid crystal display element
LP proposed in the above-mentioned publication. In FIG. 13, the
reference numeral 16 designates a microlens array comprising a
plurality of microlenses 16a arranged at a predetermined pitch, the
reference numeral 17 denotes a liquid crystal layer, and the
reference numeral 18 designates R (red), G (green) and B (blue)
pixels.
[0006] This element LP is designed such that when red, green and
blue illuminating lights R, G and B are applied to the element LP
from different angles, the respective color lights enter only
corresponding color pixels 18 by the condensing action of the
microlenses 16a. By this design, color filters can be eliminated in
principle and accordingly, there is provided a display panel which
is high in light utilization efficiency.
[0007] However, in such a conventional projection type display
apparatus, R, G and B color pixels 18 are enlargedly projected onto
a screen and therefore, as shown in FIG. 14 of the accompanying
drawings, the mosaic structure of the R, G and B pixels becomes
conspicuous on the screen, and this has led to the disadvantage
that the quality of a displayed image is reduced.
SUMMARY OF THE INVENTION
[0008] The present invention has as its object the provision of a
display panel and a projection type display apparatus capable of
displaying an image of high quality.
[0009] The display panel of the present invention is characterized
by:
[0010] (1-1) a pixel unit array comprising pixel units having a
combination of two of, first, second and third three color pixels
disposed in a first direction and a combination of two color pixels
differing from the combination of the two color pixels disposed in
a second direction differing from the first direction, so as to
share a color pixel, the pixel units being two-dimensionally
arranged at a predetermined pitch on a substrate, and a microlens
array comprising a plurality of microlenses in which the pitch of
the two color pixels in the first direction and the second
direction is one pitch, the plurality of microlenses being
two-dimensionally arranged on the pixel unit array on the
substrate.
[0011] The display panel of the present invention is characterized
by:
[0012] (1-2) a pixel unit array comprising pixel units having a
combination of first and second color pixels of, first, second and
third three color pixels disposed in a first direction and a
combination of the first and third color pixels disposed in a
second direction differing from the first direction, so as to share
the first color pixel, the pixel units being two-dimensionally
arranged at a predetermined pitch on a substrate, and a microlens
array comprising a plurality of microlenses in which the pitch of
the two color pixels in the first direction and the second
direction is one pitch, the plurality of microlenses being
two-dimensionally arranged on the pixel unit array on the
substrate.
[0013] Particularly, in the construction (1-1) or (1-2), the
display panel of the present invention is characterized in
that:
[0014] (1-2-1) the first color pixel is located at a position
corresponding to the central portion of the microlenses, the second
color pixel is located at a position corresponding to the boundary
portion between the microlenses of the microlens array in the first
direction, and the third color pixel is located at a position
corresponding to the boundary portion between the microlenses of
the microlens array in the second direction;
[0015] (1-2-2) the three color pixels comprise reflection
electrodes and are comprised of liquid crystal of a reflection
display mode;
[0016] (1-2-3) the three color pixels comprise reflection
electrodes and use the DMD operation of the reflection electrodes;
and
[0017] (1-2-4) the three color pixels utilize liquid crystal, and
two microlens arrays in the same state of arrangement are provided
at positions symmetrical with respect to a liquid crystal layer so
as to sandwich the liquid crystal layer therebetween.
[0018] The projection type display apparatus of the present
invention is characterized by:
[0019] (2-1) a display panel having a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of the first and third color pixels
disposed in a second direction differing from the first direction,
so as to share the first color pixel, the pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in the first direction and
the second direction is one pitch, the plurality of microlenses
being two-dimensionally arranged on the pixel unit array on the
substrate, the first color pixel being located at a position
corresponding to the central portion of the microlenses,
illuminating means for causing a first color light to enter the
display panel perpendicularly thereto, causing a second color light
to enter the display panel while being inclined in the first
direction, and causing a third color light to enter the display
panel while being inclined in the second direction, and projecting
means for projecting a light beam light-modulated by the display
panel onto a predetermined surface.
[0020] Particularly, the projection type display apparatus of the
present invention is characterized in that
[0021] (2-1-1) light beams from the three color pixels constituting
the pixel units pass through the same microlens and enter the
projecting means.
[0022] The projection type display apparatus of the present
invention is characterized by:
[0023] (2-2) a display panel having a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of the first and third color pixels
disposed in a second direction differing from the first direction,
so as to share the first color pixel, the pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in the first direction and
the second direction is one pitch, the plurality of microlenses
being two-dimensionally arranged on the pixel unit array on the
substrate, the first color pixel being located at a position
corresponding to the central portion of the microlenses,
illuminating means for causing a first color light to enter the
display panel perpendicularly thereto, causing a second color light
to enter the display panel while being inclined in the first
direction, and causing a third color light to enter the display
panel while being inclined in the second direction, and projecting
means for projecting a light beam light-modulated by the display
panel onto a predetermined surface, the reflected lights from the
three color pixels constituting the pixel units light-modulated by
the display panel passing through the same microlens and being
directed to the projecting means.
[0024] Particularly, in the construction (2-1) or (2-2), the
projection type display apparatus of the present invention is
characterized in that (2-2-1) the illuminating means color-resolves
white light from a light source into a plurality of color lights by
the use of a plurality of dichroic mirrors so that by the
disposition of the plurality of dichroic mirrors, the plurality of
color lights may be applied to the three color pixels from
different directions for the respective color lights; and
[0025] (2-2-2) the projecting means projects the disposition
surface of the microlenses or the vicinity thereof onto a
predetermined surface.
[0026] The direct-view type display apparatus of the present
invention is characterized by:
[0027] (3-1) a display panel having a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of the first and third color pixels
disposed in a second direction differing from the first direction,
so as to share the first color pixel, the pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in the first direction and
the second direction is one pitch, the plurality of microlenses
being two-dimensionally arranged on the pixel unit array on the
substrate, the first color pixel being located at a position
corresponding to the central portion of the microlenses,
illuminating means for causing a first color light to enter the
display panel perpendicularly thereto, causing a second color light
to enter the display panel while being inclined in the first
direction, and causing a third color light to enter the display
panel while being inclined in the second direction, and an eyepiece
for directing a light beam light-modulated by the display panel to
an observer's eyeball so that image information based on the light
beam may be observed.
[0028] The display apparatus of the present invention is
characterized by:
[0029] (4-1) a display panel having a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of the first and third color pixels
disposed in a second direction differing from the first direction,
so as to share the first color pixel, the pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in the first direction and
the second direction is one pitch, the plurality of microlenses
being two-dimensionally arranged on the pixel unit array on the
substrate, the first color pixel being located at a position
corresponding to the central portion of the microlenses, and
illuminating means for causing a first color light to enter the
display panel perpendicularly thereto, causing a second color light
to enter the display panel while being inclined in the first
direction, and causing a third color light to enter the display
panel while being inclined in the second direction.
[0030] The display apparatus of the present invention is
characterized by:
[0031] (4-2) a display panel having a pixel unit array comprising
pixel units having a combination of first and second color pixels
of, first, second and third three color pixels disposed in a first
direction and a combination of the first and third color pixels
disposed in a second direction differing from the first direction,
so as to share the first color pixel, the pixel units being
two-dimensionally arranged at a predetermined pitch on a substrate,
and a microlens array comprising a plurality of microlenses in
which the pitch of the two color pixels in the first direction and
the second direction is one pitch, the plurality of microlenses
being two-dimensionally arranged on the pixel unit array on the
substrate, the first color pixel being located at a position
corresponding to the central portion of the microlenses, and
illuminating means for causing a first color light to enter the
display panel perpendicularly thereto, causing a second color light
to enter the display panel while being inclined in the first
direction, and causing a third color light to enter the display
panel while being inclined in the second direction, the emergent
lights from the three color pixels constituting the pixel units
light-modulated by the display panel being designed to pass through
the same microlens.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIGS. 1A, 1B and 1C are schematic views of the essential
portions of Embodiment 1 of the projection type display apparatus
of the present invention.
[0033] FIGS. 2A, 2B and 2C are graphs showing the spectral
reflection characteristics of dichroic mirrors used in the
projection type display apparatus of the present invention.
[0034] FIG. 3 is a perspective view of the color resolving and
illuminating portion of the projection type display apparatus of
the present invention.
[0035] FIG. 4 is a cross-sectional view showing Embodiment 1 of the
liquid crystal panel of the present invention.
[0036] FIGS. 5A, 5B and 5C illustrate the principle of color
resolution and color combination in the liquid crystal panel of the
present invention.
[0037] FIG. 6 is a fragmentary enlarged top plan view of the liquid
crystal panel according to Embodiment 1 of the present
invention.
[0038] FIG. 7 shows the construction of a portion of the projection
optical system of Embodiment 1 of the projection type display
apparatus of the present invention.
[0039] FIG. 8 is a block diagram showing the driving circuit of
Embodiment 1 of the projection type display apparatus of the
present invention.
[0040] FIG. 9 is a fragmentary enlarged view of a projected image
on a screen in Embodiment 1 of the projection type display
apparatus of the present invention.
[0041] FIG. 10 is a fragmentary enlarged top plan view of another
form of the liquid crystal panel according to Embodiment 1 of the
present invention.
[0042] FIG. 11 is a fragmentary enlarged cross-sectional view
showing Embodiment 2 of the liquid crystal panel of the present
invention.
[0043] FIGS. 12A and 12B are a fragmentary enlarged top plan view
and a fragmentary enlarged cross-sectional view, respectively, of
the liquid crystal panel according to Embodiment 2 of the present
invention.
[0044] FIG. 13 is an enlarged cross-sectional view of a portion of
a transmission type liquid crystal display element with a microlens
array according to the prior art.
[0045] FIG. 14 is a fragmentary enlarged view of an image
enlargedly projected onto a screen in a projection type display
apparatus according to the prior art.
[0046] FIG. 15 is a typical cross-sectional view of an active
matrix driving circuit portion in a liquid crystal panel according
to the present invention.
[0047] FIG. 16 is a circuit diagram of the active matrix driving
portion in the liquid crystal panel according to the present
invention.
[0048] FIG. 17 is a typical block diagram of the peripheral driving
circuit (another form) of the liquid crystal panel according to the
present invention.
[0049] FIG. 18 is a typical general plan view of the liquid crystal
panel according to the present invention.
[0050] FIGS. 19A and 19B are graphs showing the etching
characteristics of reflection electrodes in the liquid crystal
panel according to the present invention.
[0051] FIG. 20 is a typical view showing the general construction
of Embodiment 3 of the direct viewer type liquid crystal display
apparatus of the present invention.
[0052] FIG. 21 is a perspective view of the rear surfaces of the R,
G and B LED's of FIG. 20.
[0053] FIG. 22 is a perspective view of an illuminating system in
Embodiment 4 of the display apparatus of the present invention.
[0054] FIG. 23 is a fragmentary enlarged cross-sectional view of a
display panel using a DMD device with microlenses according to
Embodiment 5 of the present invention.
[0055] FIGS. 24A, 24B and 24C show the general construction of
Embodiment 6 of the projection type display apparatus using the
transmission type liquid crystal panel of the present
invention.
[0056] FIG. 25 is a cross-sectional view of the transmission type
liquid crystal panel according to Embodiment 6 of the present
invention.
[0057] FIGS. 26A, 26B and 26C illustrate the principle of color
resolution and color combination in the transmission type liquid
crystal panel according to Embodiment 6 of the present
invention.
[0058] FIG. 27 is a fragmentary enlarged top plan view of the
transmission type liquid crystal panel according to Embodiment 6 of
the present invention.
[0059] FIG. 28 is a fragmentary construction view showing the
projection optical system of a projection type display apparatus
using the transmission type liquid crystal panel according to
Embodiment 6 of the present invention.
[0060] FIG. 29 shows the layout of the TFT portion of the
transmission type liquid crystal panel according to Embodiment 6 of
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0061] FIGS. 1A, 1B and 1C are schematic views of the essential
portions of the optical system of Embodiment 1 of the display panel
and projection type liquid crystal display apparatus of the present
invention. FIG. 1A is a top plan view of this optical system, FIG.
1B is a front view of this optical system, and FIG. 1C is a side
view of this optical system.
[0062] In FIGS. 1A to 1C, the reference numeral 1 designates a
projection lens which projects full color image (information)
displayed by a liquid crystal display panel (liquid crystal panel)
2 with a microlens array onto a screen or a wall. The reference
numeral 3 denotes a polarizing beam splitter (PBS). The PBS 3
transmits P-polarized light therethrough and reflects S-polarized
light. The reference numeral 40 designates a dichroic mirror which
reflects only red light (R), the reference numeral 41 denotes a
dichroic mirror which reflects only blue and green lights (B and
G), the reference numeral 42 designates a dichroic mirror which
reflects only blue light (B), the reference numeral 43 denotes a
high reflection mirror which reflects all color lights R, G and B,
the reference numeral 50 designates a Fresnel lens, the reference
numeral 51 denotes a convex lens (positive lens), the reference
numeral 6 designates a rod type (inner surface reflection type)
integrator, and the reference numeral 7 denotes an elliptical
reflector, at the center of which there is disposed the light
emitting portion of a light source 8 comprising an arc lamp such as
a metal halide lamp or a UHP lamp.
[0063] The R reflecting dichroic mirror 40, the B/G reflecting
dichroic mirror 41 and the B reflecting dichroic mirror 42 have
spectral reflection characteristics as shown in FIGS. 2A, 2B and
2C, respectively. These dichroic mirrors 40, 41 and 42, with the
high reflection mirror 43, are three-dimensionally disposed as
shown in the perspective view of FIG. 3, and the mirrors 40, 41, 42
and 43, as will be described later, are designed to color-resolve
the white light from the light source 8 into three R, G and B color
lights and such that the R, G and B primary color lights illuminate
the liquid crystal panel 2 from three-dimensionally different
directions relative to the liquid crystal panel 2.
[0064] Describing here in accordance with the travelling process of
the light beam from the light source 8, a white light beam emitted
from the lamp 8 is first reflected by the elliptical reflector 7
and is condensed on the entrance (light incidence surface) 6a of
the integrator 6 forward of the reflector 7, and as it travels
through this integrator 6 while repeating reflection on the inner
surface thereof, the spatial light intensity distribution thereof
(of the white light beam) is uninformized. The light beam emerging
from the exit (light emergence surface) of the integrator 6 is made
into a parallel light beam in the x-axis-direction (reference) by
the convex lens 51 and the Fresnel lens 50, and first comes to the
B reflecting dichroic mirror 42.
[0065] Only B (blue light) is reflected by this B reflecting
dichroic mirror 42 and travels toward the R reflecting dichroic
mirror 40 in the z-axis-direction, i.e., downwardly (reference in
FIG. 1B) at a predetermined angle with respect to the z-axis. On
the other hand, the other color lights (R/G) than B pass through
this B reflecting dichroic mirror 42, whereafter they are reflected
at a right angle in the z-axis-direction (downwardly) by the high
reflection mirror 43, and travel toward the R reflecting dichroic
mirror 40.
[0066] Explaining here on the basis of FIG. 1A, both of the B
reflecting dichroic mirror 42 and the high reflection mirror 43 are
disposed so as to reflect the x-axis-direction light beam from the
integrator 6 in the z-axis-direction (downwardly), and the high
reflection mirror 43 is inclined at just 45.degree. with respect to
xy plane with the y-axis direction as a rotational axis. In
contrast, the B reflecting dichroic mirror 42 is set to an angle
smaller than 45.degree. with respect to xy plane with the y-axis
direction as a rotational axis.
[0067] Accordingly, R/G reflected by the high reflection mirror 43
are reflected in the z-axis-direction, whereas B reflected by the B
reflecting dichroic mirror 42 travels downwardly at a predetermined
angle (inclined in xz plane) with respect to the z-axis. In order
to make the illumination ranges of the three B and R/G primary
color lights on the liquid crystal panel 2 coincident with one
another, the amounts of shift and the amounts of tilt of the high
reflection mirror 43 and the B reflecting dichroic mirror 42 are
set so that the principal rays (central rays) of the respective
color lights may intersect with one another on the liquid crystal
panel 2.
[0068] Next, the three R, G and B primary color lights travelling
downwardly (in the z-axis-direction) as previous described travel
toward the R reflecting dichroic mirror 40 and the B/G reflecting
dichroic mirror 41, but these are located under the B reflecting
dichroic mirror 42 and the high reflection mirror 43, and the B/G
reflecting dichroic mirror 41 is inclined at 45.degree. with
respect to xz plane with the x-axis as a rotational axis, and the R
reflecting dichroic mirror 40 is set to an angle smaller than
45.degree. with respect to xz plane with the x-axis direction as a
rotational axis.
[0069] Accordingly, of R, G and B incident on these, B/G pass
through the R reflecting dichroic mirror 40 and are reflected at a
right angle in the y-axis + direction by the B/G reflecting
dichroic mirror 41, and P-polarized lights alone are taken out by
the PBS 3. These blue and green P-polarized lights illuminate the
liquid crystal panel 2 horizontally disposed in xz plane.
[0070] The blue light B has already travelled at a predetermined
angle (inclined in xz plane) with respect to the x-axis as
previously described (see FIGS. 1A and 1B) and therefore, after it
is reflected by the B/G reflecting dichroic mirror 41, it maintains
a predetermined angle (inclined in xy plane) with respect to the
y-axis, and P-polarized light alone is taken out by the PBS 3. This
blue P-polarized light illuminates the liquid crystal panel 2 with
the angle with respect to the y-axis as an angle of incidence (the
direction of xy plane). The green light G is reflected at a right
angle by the B/G reflecting dichroic mirror 41 and travels in the
y-axis + direction, and P-polarized light alone is taken out by the
PBS 3. This green P-polarized light illuminates the liquid crystal
panel 2 at an angle of incidence of 0.degree., i.e., from a
perpendicular direction.
[0071] Also, the red light R is reflected in the y-axis + direction
by the R reflecting dichroic mirror 40 disposed short of the B/G
reflecting dichroic mirror 41, as previously described, and travels
in the y-axis + direction at a predetermined angle (inclined in yz
plane) with respect to the y-axis as shown in FIG. 1C (a side
view), and P-polarized light is taken out by the PBS 3. This red
P-polarized light illuminates the liquid crystal panel 2 with this
angle with respect to the y-axis as an angle of incidence (the
direction of yz plane).
[0072] Also, in order to make the illumination ranges of the R, G
and B color lights on the liquid crystal panel 2 coincident with
one another, the amounts of shift and the amounts of tilt of the
B/G reflecting dichroic mirror 41 and the R reflecting dichroic
mirror 40 are set so that the principal rays of the respective
color lights may intersect with one another on the liquid crystal
panel 2.
[0073] Further, as shown in FIGS. 2A to 2C, the cut wavelength of
the B/G reflecting dichroic mirror 41 is 570 nm and the cut
wavelength of the R reflecting dichroic mirror 40 is 600 nm and
therefore, unnecessary orange-colored light is transmitted through
the B/G reflecting dichroic mirror 41 and is discarded out of the
optical path. Thereby, optimum color balance is obtained.
[0074] Also, as will be described later, the three R, G and B
primary color lights are reflected and polarized by the liquid
crystal panel 2, and thereafter return to the PBS 3, and
S-polarized lights alone are reflected in the x-axis + direction by
the PBS surface 3a of the PBS 3. These S-polarized lights of the
respective colors enter the projection lens 1, which thus enlarges
and projects an image displayed on the liquid crystal panel 2 by
these S-polarized lights of the respective colors onto a screen or
a wall.
[0075] The R, G and B color lights illuminating the liquid crystal
panel 2 differ in the angle of incidence onto the panel from one
another and therefore, the R, G and B lights which are the lights
reflected from the panel also differ in the angle of emergence from
one another and thus, as the projection lens 1, use is made of one
having a lens diameter and aperture of sufficient size to introduce
these reflected lights of the respective colors. However, the
expanse of the whole of the light beam from the panel 2 which
enters the projection lens 1 maintains the expanse of the whole of
the light beam when it has entered the liquid crystal panel 2, by
each color light passing twice through the microlens.
[0076] However, in the transmission type liquid crystal display
element LP according to the prior art shown in FIG. 13, the whole
of a light beam emerging from the liquid crystal display element LP
expands more greatly with the aid of also the condensing action of
the microlens 16 and therefore, in order to take in this greatly
expanded light beam, a very great numerical aperture has been
required of the projection lens, and this has led to a bulky
projection lens.
[0077] In contrast, the expanse of the light beam from the liquid
crystal panel 2 in the present embodiment is small as compared with
that in the prior art of FIG. 13 and therefore, even a projection
lens of a numerical aperture smaller than that in the prior art can
enlarge and project a sufficiently bright image onto a wall or a
screen and thus, it becomes possible to use a more compact
projection lens.
[0078] The liquid crystal panel 2 will now be described in detail.
FIG. 4 is a typical enlarged cross-sectional view (corresponding to
the yz plane of FIG. 1C) of the liquid crystal panel 2 according to
the present embodiment.
[0079] The reference numeral 21 designates a microlens array
substrate (glass substrate), the reference characters 22, 22a and
22b denote microlenses, the reference numeral 23 designates sheet
glass, the reference numeral 24 denotes a transparent opposed
electrode, the reference numeral 25 designates a liquid crystal
layer, the reference numeral 26 denotes pixel electrodes, the
reference numeral 27 designates an active matrix driving circuit
portion, and the reference numeral 28 denotes a semiconductor
substrate formed of silicon. A number of microlenses 22 are formed
on the surface of the glass substrate (glass of the alkaline
origin) 21 by the so-called ion exchange method, and have fly-eye
lenses two-dimensionally arranged in xz plane at a pitch twice as
great as the pitch of the pixel electrodes 26, and form a so-called
microlens array.
[0080] The liquid crystal layer 25 adopts nematic liquid crystal of
ECB mode such as so-called DAP or HAN suited for the reflection
type, and has its predetermined orientation maintained by an
orientation layer, not shown, in a state in which an electric field
is not applied. The pixel electrodes 26 serving also as a
reflecting mirror are formed of Al (aluminum), and are subjected to
the so-called CMP processing at the final step after pattering to
make the surface property thereof good and improve the reflectance
thereof (the details of this will be described later).
[0081] The active matrix driving circuit portion 27 is a
semiconductor circuit provided on the silicon semiconductor
substrate 28, and serves to active-matrix-drive the pixel
electrodes 26. A gate line driver (a vertical register or the like)
and a signal line driver (a horizontal register or the like), not
shown, are provided around the circuit portion 27 (the details of
this will be described later).
[0082] These surrounding drivers and the active matrix driving
circuit portion 27 are designed to write R, G and B primary color
image signals into predetermined R, G and B pixels, and each pixel
electrode 26 does not have a color filter, but the pixel electrodes
26 are distinguished as R, G and B pixels by the primary color
image signals written in by the active matrix driving circuit 27,
and form a predetermined R, G and B pixel arrangement which will be
described later.
[0083] Description will first be made here of the green light G of
the illuminating lights to the liquid crystal panel 2. As
previously described, the green light G is made into P-polarized
light by the PBS 3, whereafter it enters the liquid crystal panel 2
perpendicularly thereto. An example of the light beam of this light
G which enters a microlens 22a is indicated by arrows G (in/out) in
FIG. 4.
[0084] As shown in FIG. 4, the light beam G is condensed by the
microlens 22a and illuminates a G pixel electrode 26g. It is
reflected by the pixel electrode 26g formed of aluminum, and again
emerges out of the liquid crystal panel 2 through the same
microlens 22a. When it thus reciprocally passes through the liquid
crystal layer 25, the light beam G is subjected to polarization
modulation by the liquid crystal having had its oriented state
changed by an electric field formed between it and the opposed
electrode 24 by a signal voltage applied to the pixel electrode
26g, and emerges from the liquid crystal panel 2 in a form
including S-polarized light and returns to the PBS 3. Here, the
quantity of image light (S-polarized light) reflected by the
surface 3a of the PBS depending on the degree of modulation thereof
and travelling toward the projection lens 1 changes and thus, the
so-called gradation harmony display of the G pixel is done.
[0085] On the other hand, the R light obliquely entering the panel
4 in the cross-section (yz plane) in FIG. 4 as described above is
also made into P-polarized light by the PBS 3, whereafter the light
beam R entering, for example, the microlens 22b is condensed by the
microlens 22b, as indicated by arrows R (in) in FIG. 4, and
illuminates an R pixel electrode 26r lying at a position shifted to
the left from just beneath it. It is then reflected by this pixel
electrode 26r formed of aluminum, and as shown, now emerges out of
the liquid crystal panel 2 through a microlens 22a neighboring in
-z direction (R (out)).
[0086] In this case, the light beam G is subjected to polarization
modulation by the liquid crystal having had its oriented state
changed by an electric field formed between it and the opposed
electrode 24 by a signal voltage also applied to the R pixel
electrode 26r, and emerges from the liquid crystal panel 2 in a
form including S-polarized light and returns to the PBS 3. The
process thereafter is entirely the same as in the case of the
aforedescribed light beam G, and the gradation harmony display of
the R pixel is done.
[0087] Now, in FIG. 4, the color lights G and R on the G pixel
electrode 26g and on the R pixel electrode 26r are depicted as
partly overlapping and interfering with each other, but this is
because typically the thickness of the liquid crystal layer 25 is
exaggerated by depicted, and actually the thickness of the liquid
crystal layer 25 is the order of 5.mu. at greatest, and this
thickness is very small as compared with the thickness of 50 to
100.mu. of the sheet glass and therefore, such interference does
not occur independently of the pixel size.
[0088] FIGS. 5A, 5B and 5C illustrate the principle of color
resolution and color combination in the liquid crystal panel in the
present embodiment. FIG. 5A is a typical top plan view of the
liquid crystal panel 2, and FIGS. 5B and 5C are typical
cross-sectional views of the liquid crystal panel taken along the
line 5B-5B (x-direction) and the line 5C-5C (z-direction),
respectively, of FIG. 5A.
[0089] FIG. 5C is a cross-sectional view corresponding to FIG. 4
representing yz cross-section, and shows the states of the
incidence and emergence of G and R color lights entering each
microlens 22. As can be seen from FIG. 5C, each G pixel electrode
as a first color pixel is disposed right beneath the center of each
microlens 22, and each R pixel electrode as a second color pixel is
disposed right beneath the boundary between the microlenses 22.
Accordingly, it is preferable that the angle of incidence .theta.
of R light be set so that tan .theta. may become equal to the ratio
between the pitch of the G and R pixels alternately arranged and
the distance in y-direction between the microlens 22 and the pixel
electrode 26.
[0090] On the other hand, FIG. 5B corresponds to the xy
cross-section of the liquid crystal panel 2. As regards this xy
cross-section, B pixel electrodes as third color pixels and G pixel
electrodes as first color pixels are alternately arranged as in
FIG. 5C, and each G pixel electrode is also disposed right beneath
the center of each microlens 22, and each B pixel electrode as the
third color pixel is disposed right beneath the boundary between
the microlenses 2.
[0091] Now, the light beam B illuminating the liquid crystal panel
2, as previously described, is made into P-polarized light by the
PBS 3, whereafter it obliquely enters the panel 2 in the
cross-section (xy plane) in FIG. 5B and therefore, just as in the
case of the light beam R, the light beam B which has entered each
microlens 22 is reflected by the B pixel electrode formed of
aluminum as shown, and emerges from a microlens adjacent to the
microlens 22 which is has entered in x-direction in a form
including S-polarized light. The polarization modulation by the
liquid crystal layer 25 on the B pixel electrode and the projection
of the emergent light from the liquid crystal panel 2 are similar
to those of the aforedescribed G and R lights.
[0092] Also, each B pixel electrode is disposed right beneath the
boundary between the microlenses 22, and it is preferable that the
angle of incidence .theta. of the blue light B onto the liquid
crystal panel 2 be set so that as in the case of the red light R,
tan .theta. may become equal to the ratio between the pitch of the
G and B pixels alternately arranged and the distance in y-direction
between the microlens 22 and the pixel electrode 26.
[0093] Now, in the liquid crystal panel 2 according to the present
embodiment, as described above, the arrangement of the R, G and B
pixels is RGRGRG . . . for z-direction (first direction), and
BGBGBG . . . for x-direction (second direction), and FIG. 5A shows
the planar arrangement thereof.
[0094] The size of the color pixels in the arrangement direction
thereof is about a half of the diameter of the microlenses 22 in a
corresponding direction, both vertically and horizontally, and the
pitch of the pixels is a half of the pitch of the microlenses 22 in
a corresponding direction, both vertically and horizontally. Also,
the G pixel is in terms of plane located right beneath the center
of the microlenses 22, and the R pixel is located between the G
pixels in z-direction and at the boundary between the microlenses
22, and the B pixel is located between the G pixels in x-direction
and at the boundary between the microlenses 22. Also, the shape of
a microlens is a square (the size of a side of which is twice as
great as that of a side of the pixel).
[0095] FIG. 6 is an enlarged top plan view of a portion of the
liquid crystal panel 2 according to the present embodiment. In FIG.
6, a broken line lattice 29 shows a pixel unit in which three R, G
and B color pixels constituting a picture element are brought
together.
[0096] Such pixel units 29 are two-dimensionally arranged in x-and
z-directions at a predetermined pitch on a substrate to thereby
constitute a pixel unit array. That is, when the R, G and B pixels
are driven by the active matrix driving circuit portion 27 of FIG.
4, the pixel units 29 are driven by R, G and B image signals
corresponding to the same picture element position.
[0097] Here, paying attention to a picture element comprising the R
pixel electrode 26r, the G pixel electrode 26g and the B pixel
electrode 26b, the R pixel electrode 26r is illuminated with the
red light R emerging from the microlens 22b and obliquely entering
it as indicated by arrow r1, and the red reflected light R emerges
through the microlens 22a as indicated by arrow r2. The B pixel
electrode 26b is illuminated with the blue light B emerging from
the microlens 22c and obliquely entering it as indicated by arrow
b1, and the blue reflected light B emerges also through the
microlens 22a as indicated by arrow b2.
[0098] Also, the G pixel electrode 26g is illuminated with the
green light G entering perpendicularly (in a direction toward the
back of the plane of the drawing sheet) from the microlens 22a, as
indicated by arrow g12 toward the front and rear, and the green
reflected light G emerges perpendicularly (in a direction going out
toward this side of the plane of the drawing sheet) through the
same microlens 22a.
[0099] As described above, in the liquid crystal panel 2, with
regard to the pixel unit 29 comprising the R, G and B color pixels
constituting a picture element, the incidence positions of the
illuminating lights of the three primary colors on the microlens
array differ from one another, but their emergence position is one
and the same microlens (in this case, the microlens 22a). This also
holds true of all the other picture elements (R, G and B pixel
units).
[0100] FIG. 7 is a schematic view when all the emergent lights from
the liquid crystal panel 2 in the present embodiment are projected
onto a screen 9 through the PBS 3 and the projection lens 1. When
as shown in FIG. 7, the liquid crystal panel 2 shown in FIG. 6 is
used and the optical system is adjusted so that the microlens array
22 in the liquid crystal panel 2 or the area near it may be imaged
on the screen 9, the image enlargedly projected onto the screen 9
comes to have as its constituent unit a picture element in a state
in which emergent lights from the R, G and B pixel units
constituting a picture element in a lattice comprising a number of
microlenses 22 as shown in FIG. 9 are mixed with one another in
colors, that is, a state in which the same pixels are mixed with
one another in colors.
[0101] In the present embodiment, the display panel 2 of the
construction shown in FIG. 6 is thus used and the microlens array
22 on the light emergence side of the panel 2 or the vicinity
thereof is made conjugate with the screen 9, whereby the display of
a full color image of high quality free of the so-called R, G and B
mosaic is made possible on the surface of the screen.
[0102] Detailed description will now be made of each pixel
electrode 26 and the active matrix driving circuit portion 27
provided on a silicon semiconductor substrate 28 for actively
driving the pixel electrodes 26.
[0103] FIG. 15 is a typical cross-sectional view of the active
matrix driving circuit portion 27 of the liquid crystal panel 2
according to the present invention. In FIG. 15, the reference
numeral 28 designates a silicon substrate (semiconductor
substrate), the reference numerals 102 and 102' denotes a p type
well and an n type well, respectively, the reference numerals 103
and 103' designate the drain areas of transistors, the reference
numeral 104 denotes a gate, and the reference numerals 105 and 105'
designate source areas.
[0104] As can be seen from FIG. 15, the transistor in the display
area is not formed with a source layer and a drain layer
self-adjustingly to the gate, but is endowed with an offset, and
therebetween, n-layers and p-layers of low density are provided as
indicated in the drain areas 103' and the gates 105'. The amount of
this offset is preferably 0.5 to 2.0 .mu.m.
[0105] On the other hand, some circuit portions of the peripheral
circuit are shown in FIG. 15, and some circuits of the peripheral
portion are formed with a source layer and a drain layer
self-adjustingly to the gate.
[0106] While the offset of the source and drain has been described
here, not only the presence or absence of the offset, but also a
change in the amount of the offset in conformity with the withstand
pressure or the optimization of the length of the gate is
effective. A portion of the peripheral circuit is a logic system
circuit, and this portion may be the above-mentioned 1.5 to 5V
system driving and therefore, the above-described self-adjusting
structure is provided to reduce the size of the transistors and
improve the driving force of the transistors.
[0107] The semiconductor substrate 28 comprises a p type
semiconductor, and the substrate 28 is of minimum potential
(usually the ground potential), and in the case of the display
area, the n type well requires a voltage applied to the pixels,
i.e., 10 to 15V, while on the other hand, the logic portion of the
peripheral circuit requires a logic driving voltage of 1.5 to 5V.
By this structure, optimum devices conforming to the respective
voltages can be constructed, and it becomes possible to realize not
only a reduction in chip size, but also high pixel display by an
improved driving speed.
[0108] The reference numeral 106 designates field oxidizes film,
the reference numeral 110 denotes source electrodes connected to
data wiring, the reference numeral 111 designates a drain electrode
connected to the pixel electrode 26. The reference numeral 107
denotes a light intercepting layer covering a display area and a
peripheral area, and Ti, TiN, W, Mo or the like is suitable as this
light intercepting layer 107.
[0109] As can be seen from FIG. 15, the light intercepting layer
covers the display area except the connecting portion between the
pixel electrode and the source electrode, but is designed in the
peripheral pixel area to cover the pixel electrode layer when the
illuminating light mixes into a portion from which the light
intercepting layer has been removed to thereby cause the
malfunctioning of the circuit, except for the light intercepting
layer in an area wherein wiring capacity such as some image signal
lines and a clock line becomes heavy, and is contrived so as to be
capable of transferring a high speed signal.
[0110] The reference numeral 108 designates an insulating layer in
the lower portion of the light intercepting layer, and a P-SiO
layer has been subjected to the flattening process by SOG, and that
layer has been further covered with P-SiO to thereby secure the
stability of the insulating layer. Of course, besides the
flattening by SOG, P-TEOS film may be formed and P-SiO is covered,
whereafter the insulating layer may be CMP-processed and
flattened.
[0111] The reference numeral 109 denotes an insulating layer
provided between a reflection electrode and the light intercepting
layer, and the charge holding capacity of the reflection electrode
is provided through this insulating layer. For the formation of a
great capacity, laminated film of P-SiN, Ta.sub.2O.sub.5 and
SiO.sub.2 of high dielectric constant is effective besides
SiO.sub.2. The light intercepting layer is provided on a flat metal
such as Ti, TiN, Mo or W, whereby a film thickness of the order of
500 to 5000 angstrom is suitable.
[0112] The reference numeral 25 designates a liquid crystal
material, the reference numerals 117 and 117' denote high density
impurity areas, and the reference numeral 119 designates a display
area.
[0113] As can be seen from FIG. 15, the high density impurity
layers 117 and 117' identical in polarity to the well formed in the
lower portion of the transistor are formed on the peripheral
portion and interior of the well, and even if a signal of high
amplitude is applied to the source, the potential of the well is
stable because it is fixed at desired potential in a low resistance
layer, and therefore image display of high quality can be realized.
Further, between the n type well and the p type well, the high
density impurity layers 117 and 117' are provided through field
oxidized film, whereby a channel stop layer right beneath the field
oxidized film usually used in the case of an MOS transistor is made
unnecessary.
[0114] These high density impurity layers can be formed at a time
by the source and drain layer forming process and therefore, the
number of masks and the number of steps in the manufacturing
process could be curtailed to thereby achieve a reduction in
cost.
[0115] FIG. 16 is a circuit diagram of the active matrix driving
portion 27 of the liquid crystal panel 2 in the present
embodiment.
[0116] In FIG. 16, the reference numeral 121 designates a
horizontal shift register, the reference numeral 122 denotes a
vertical shift register, the reference numeral 123 designates an n
channel MOSFET, the reference numeral 124 denotes a p channel
MOSFET, the reference numeral 125 designates a holding capacity,
the reference numeral 126 denotes a liquid crystal pixel capacity,
the reference numeral 127 designates a signal transfer switch, the
reference numeral 128 denotes a reset switch, the reference numeral
129 designates a reset pulse input terminal, the reference numeral
130 denotes a reset power source terminal, and the reference
numeral 131 designates R, G and B image signal input terminals.
[0117] While in FIG. 15, the silicon semiconductor substrate 28 is
of p type, it may be of n type. Also, the well area 102 is of an
electrically conductive type opposite to the semiconductor
substrate 28. Therefore, in FIG. 15, the well area 102 is of p
type. It is desirable the p type and n type well areas 102 and 102'
have impurities poured thereinto at higher density than the
semiconductor substrate 28, and it is desirable that when the
density of the impurities of the semiconductor substrate 28 is
10.sup.14 to 10.sup.15 (cm.sup.-3), the density of the impurities
of the well area 102 be 10.sup.15 to 10.sup.17 (cm.sup.-3).
[0118] The source electrode 110 is connected to data wiring to
which a signal for display is sent, and the drain electrode 111 is
connected to the pixel electrode 26. Al, AlSi, AlSiCu, AlGeCu or
AlCu wiring is usually used as these electrodes 110 and 111. When a
barrier metal layer formed of Ti and TiN is used in the lower
portions of these electrodes 110 and 111, contact can be realized
stably. Also, contact resistance can be reduced.
[0119] It is desirable that the pixel electrode 26 have a flat
surface and have a high reflectance, and it is possible to use a
material such as Cr, Au or Ag besides Al, AlSi, AlSiCu, AlGeCu and
AlCu which are ordinary metals for wiring. Also, to improve the
flatness of the pixel electrode 26, the ground insulating layer and
the surface of the pixel electrode 26 can preferably be processed
by the chemical mechanical polishing (CMP) method.
[0120] The holding capacity 125 shown in FIG. 16 is a capacity for
holding the signal between the pixel electrode 26 shown in FIG. 15
and the opposed transparent electrode 24. Substrate potential is
applied to the well area 102.
[0121] In the present embodiment, the transmission gate
construction in respective rows is made into a construction in
which the order is changed in adjacent rows so that in the first
row from above, an n channel MOSFET 123 may be upper and a p
channel MOSFET 124 may be lower and in the second row, a p channel
MOSFET 124 may be upper and an n channel MOSFET 123 may be lower.
As described above, not only in the stripe type well, the periphery
of the display area is in contact with a power source line, but
also in the display area, a thin power source line is provided and
contact is made therewith.
[0122] At this time, the stabilization of the resistance of the
well becomes a key. Accordingly, in the case of a p type substrate,
there has been adopted a construction in which the area of contact
or the number of contacts in the display area of the n well is
augmented more than the contact in the p well. The p well is a p
type substrate in which constant potential is adopted and
therefore, the substrate plays the role of a low resistance body.
Accordingly, the influence of the swing by the inputting and
outputting of a signal to the source and drain of the n type well
which becomes stripe-like is liable to become great, but it can be
prevented by augmenting the contact from the upper wiring layer,
whereby stable display of high quality can be realized.
[0123] R, G and B image signals (such as video signals and
pulse-modulated digital signals) are inputted from the image signal
input terminal 131, and are outputted to each data wiring with the
signal transfer switch 127 opened and closed in conformity with a
pulse from the horizontal shift register 121. From the vertical
shift register 122, a high pulse is applied to the gate of the n
channel MOSFET 123 in the selected row and a low pulse is applied
to the gate of the p channel MOSFET.
[0124] As described above, the switch of the pixel portion is
comprised of a CMOS transmission gate of single crystal, and has
the advantage that a signal written into the pixel electrode does
not depend on the therehold value of MOSFET, but the signal of the
source can be fully written in.
[0125] Also, the switch comprises a single crystal transistor and
is free of unstable behavior or the like in the grain boundary of
poly Si-TFT, and highly reliable high-speed driving free of
irregularity can be realized.
[0126] Also, the active matrix driving circuit portion 27 as
described above is present under each pixel electrode 26 and
therefore, in the circuit diagram of FIG. 16, the R, G and B pixels
constituting a picture element are simply depicted as being
laterally arranged, but the drain of each pixel FET is connected to
the two-dimensionally arranged R, G and B pixel electrodes 26 as
shown in FIG. 6.
[0127] Another example of the construction of the driving circuit
around the panel will now be described with reference to FIG.
17.
[0128] FIG. 17 is a typical block diagram showing another example
of the construction of the driving circuit around the panel. In
FIG. 17, the reference numeral 132 designates a level shifter
circuit, the reference numeral 133 denotes image signal sampling
switches, the reference numeral 134 designates a horizontal shift
register, the reference numeral 135 denotes R, G and B image signal
input terminals, the reference numeral 136 designates a vertical
shift register, and the reference numeral 137 denotes a display
area.
[0129] By the construction described above, the logic circuits such
as the H and V shift registers could be driven at a very low value
of the order of 1.5 to 5V, irrespective of the amplitude of the
video signal, and a higher speed and a lower consumption voltage
could be achieved. The horizontal and vertical shift registers here
can be scanned in both directions by a selection switch, and can
cope with a change in the disposition or the like of the optical
system without any change of the panel, and there is the merit that
the same panel can be used even in a different series of products
and a lower cost can be achieved.
[0130] Also, in FIG. 17, the image signal sampling switches 133
each have already been described as being comprised of a transistor
of one side polarity, whereas this is not restrictive, but of
course, each of them may be comprised of a CMOS transmission gate,
whereby all of input image signals can be written into the signal
line.
[0131] Also, when the CMOS transmission gate construction is
adopted, there is the problem that swing occurs to the image
signals due to the difference in area between an NMOS gate and a
PMOS gate and the difference in overlapping capacity between the
gate and the source or the drain. To prevent this, the source and
drain of an MOSFET of about 1/2of the gate length of the MOSFET's
of the sampling switches 133 of respective polarities are connected
to the signal line, and a pulse of the opposite phase is applied
thereto, whereby the swing could be prevented and a very good image
signal has been written into the signal line. Thus, display of
higher quality has become possible.
[0132] FIG. 18 is a typical plan view for illustrating the relation
between seal structure and panel structure. In FIG. 18, the
reference numeral 151 designates a seal material, the reference
numeral 152 denotes an electrode pad, the reference numeral 153
designates a clock buffer circuit, and the reference numeral 154
denotes an amplifier. This amplifier is used as an output amplifier
during the inspection of panel electricity. The reference numeral
155 designates an Ag paste portion for taking the potential of an
opposed substrate, the reference numeral 156 denotes a display
area, and the reference numeral 157 designates a peripheral driving
circuit portion such as SR.
[0133] As can be seen from FIG. 18, in the present embodiment,
circuits are provided in both the interior and exterior of the seal
so that the total chip size may be become small. In the present
embodiment, the drawing-out of the pad is concentrated in one of
the sides of the panel, but may be on the longer side, and the
taking-out not from a side but from a plurality of sides is also
effective when a high-speed clock is handled.
[0134] Further, the liquid crystal panel (panel) according to the
present embodiment uses an Si semiconductor substrate and
therefore, when as in a projection type display apparatus, strong
light is applied thereto and light also impinges on the side walls
of the substrate, the potential of the substrate may be fluctuated
to thereby cause the wrong operation of the liquid crystal panel.
Accordingly, the peripheral circuit portion of the display area on
the side walls and upper surface of the liquid crystal panel is a
substrate holder capable of intercepting light, and the back of the
Si substrate is holder structure to which a metal such as Cu having
high heat conductivity is connected through an adhesive agent
having high heat conductivity.
[0135] Description will now be made of a reflection electrode
structure in the present embodiment and a method of making it. The
completely flattened reflection electrode structure in the present
embodiment is made by a novel method, unlike an ordinary method of
patterning a metal, and then polishing it, of subjecting an
electrode pattern to the etching of a groove in advance, forming a
metal into film there, removing the metal on an area on which the
electrode pattern is not formed and also, flattening the metal on
the electrode pattern. Moreover, the width of wiring is much
greater than that of the other area than the wiring, and according
to the common knowledge of the conventional etching apparatus,
there arises the problem that when etching is done, polymer
accumulates during the etching and patterning becomes impossible
and thus, the structure in the present embodiment cannot be
made.
[0136] So, an attempt has been made to write a condition in the
conventional oxidized film origin etching (CF.sub.4/CHF.sub.3
system).
[0137] FIGS. 19A and 19B are graphs showing the quality of the
etching process in the manufacture of the liquid crystal panel
according to the present invention. FIG. 19A shows a conventional
case where the total pressure is 1.7 torr, and FIG. 19B shows the
case of the present embodiment where the total pressure is 1.0
torr.
[0138] It can be seen that when gas CFH.sub.3 of a deposition
property is decreased under the conventional condition, the volume
of polymer certainly decreases, but the dimensional difference
between a pattern near the resist and a pattern far from the resist
(the loading effect) becomes very great and this gas cannot be
used.
[0139] It has been found this time that as the pressure is
gradually reduced to suppress the loading effect, the loading
effect is considerably suppressed when the pressure becomes equal
to or less than 1 torr, and the etching by CF.sub.4 alone in which
CHF.sub.3 is made zero is effective.
[0140] Further, little or no resist is present in the pixel
electrode area, and the peripheral portion is occupied by resist.
Accordingly, it has been found that it is difficult to form a
structure and it is effective to provide as the structure a shape
equal to the pixel electrode up to the peripheral portion of the
display area.
[0141] By adopting the present structure, there has been obtained
the effect that the level difference with respect to the display
portion and the peripheral portion or the seal portion which has
heretofore been present becomes null and gap accuracy becomes high
and not only the uniform pressure in the surface becomes high, but
also the irregularity during pouring decreases and images of high
quality can be formed with a good yield.
[0142] FIG. 8 is a general block diagram of the driving circuit
system of a projection type liquid crystal display apparatus
according to the present invention.
[0143] In FIG. 8, there reference numeral 10 designates a panel
driver which reverses the polarity of R, G and B image signals and
forms a liquid crystal driving signal subjected to predetermined
voltage amplification, and also forms a driving signal for the
opposed electrode 24, and various timing signals or the like. The
reference numeral 12 denotes an interface which decodes various
image and control transmission signals into standard image signals
or the like. The reference numeral 11 designates a decoder which
decodes the standard image signals from the interface 12 into R, G
and B primary color image signals and synchronous signals. The
reference numeral 14 denotes ballast which drives and turns on an
arc lamp 8. The reference numeral 15 designates a power supply
circuit which supplies a power source to each circuit block. The
reference numeral 13 denotes a controller containing an operating
portion, not shown, therein, which synthetically control each of
the above-mentioned circuit blocks.
[0144] As described above, the driving circuit system of the
projection type liquid crystal display apparatus according to the
present embodiment is very popular as a single plate type projector
and a burden is not particularly applied to the driving circuit
system, and a color image of good quality free of the R, G, B
mosaic as previously described can be displayed.
[0145] FIG. 10 is a fragmentary enlarged plan view of another form
of the liquid crystal panel in the present invention. Here, blue B
pixels are arranged as first color pixels right beneath the centers
of the microlenses 22, and green G pixels are arranged as second
color pixels alternately with the B pixels in the left and right
direction of the B pixels, and R pixels are arranged as third color
pixels alternately with the B pixels in the vertical direction of
the G pixels.
[0146] By such an arrangement, an effect entirely similar to that
of the previous example can be obtained by causing the blue light B
to enter the liquid crystal panel perpendicularly thereto and
causing the red light R and the green light G to enter the liquid
crystal panel obliquely thereto so that the reflected light from a
unit of R, G and B pixels constituting a picture element may emerge
a common microlens. Further, R pixels may be arranged as first
color pixels right beneath the centers of the microlenses 22, and
one of G and B color pixels may be arranged alternately with R
pixels in the left to right direction and the other of G and B
color pixels may be arranged alternately with R pixels in the
vertical direction.
[0147] FIG. 11 is a schematic view of the essential portions of a
liquid crystal panel 20 according to Embodiment 2 of the present
invention. FIG. 11 shows a fragmentary enlarged cross-sectional
view of the liquid crystal panel 20. The differences of Embodiment
2 from Embodiment 1 are that sheet glass 23 is used as the opposed
glass substrate and that microlenses 220 are formed on the sheet
glass 23 by the so-called reflow method using thermoplastic resin.
Further, spacer ports 251 are formed on non-pixel portions by the
photolithography of photo-sensitive resin.
[0148] FIG. 12A is a fragmentary top plan view of the liquid
crystal panel 20. As can be seen from this figure, the spacer posts
251 are formed in the non-pixel areas at the corners of the
microlenses 220 at a predetermined pitch. A cross-section 12B-12B
passing through these spacer posts 251 is shown in FIG. 12B. It is
preferable that these spacer posts 251 be provided in a matrix form
at 10 to 100 pixel pitch and it is necessary that the formation
density thereof be set so as to satisfy both of the parameters of
the planarity of the sheet glass 23 and the pourability of liquid
crystal which are contrary to the number of spacer posts.
[0149] Also, in the present embodiment, there is provided a light
intercepting layer 221 formed by a pattern comprising metallic
film, and it prevents the entry of any leaking light from the
boundary portions among the microlenses. Thereby, a reduction in
the chromaticness of a projected image by such leaking light (due
to the mixing of the three primary color image lights R, G and B)
and a reduction in contrast are prevented. Accordingly, by using
the present liquid crystal panel 220 to construct a projection type
display apparatus as in Embodiment 1, there are obtained more
modulated good images.
[0150] FIG. 20 is a schematic view of the essential portions of
Embodiment 3 of the projection type liquid crystal display
apparatus of the present invention. FIG. 20 typically shows the
general construction of a direct viewer type display apparatus
using a reflection type liquid crystal panel.
[0151] In FIG. 20, the reference numeral 101 designates an
eyepiece, the reference numeral 20 denotes the liquid crystal panel
shown in the aforedescribed Embodiment 2, the reference numeral 31
designates a PBS (polarizing beam splitter), the reference numeral
52 denotes a field lens, the reference numeral 44 designates a
total reflection mirror, and the reference numerals 81, 82 and 83
denote an R-LED (red light emitting diode), a G-LED (green light
emitting diode) and a B-LED (blue light emitting diode),
respectively, and these are laid out as shown.
[0152] First, R, G and B light beams emitted from the LED's 81, 82
and 83 corresponding to the three primary colors are reflected by
the mirror 44, whereafter they illuminate the liquid crystal panel
20 through the field lens 52 and the PBS 31. The field lens 52
collimates the widened light beams (divergent light beams) from the
LED's 81, 82 and 83, and the PBS 31 takes out only P-polarized
lights from the primary color illuminating lights. Further, the
liquid crystal panel 20 is such that the direction in which the
two-dimensional arrangement of a plurality of R, G and B pixels is
RGRG is the y-axis direction and the direction in which the
two-dimensional arrangement of the plurality of R, G and B pixels
is BGBG is the x-axis direction.
[0153] FIG. 21 illustrates the disposition of the LED's 81, 82 and
83. FIG. 21 shows a rear surface perspective view from the
direction of arrow A in FIG. 20. As can be seen from this figure,
the R-LED 81 is located at a position adjacent in the
z-axis-direction to the G-LED 82, and the B-LED 83 is located at a
position adjacent in the x-axis-direction to the G-LED 82, and the
directions of the respective LED's are set so that the principal
rays r, g and b (arrows in FIG. 21) of the emergent lights from the
LED's may travel toward the central position of the liquid crystal
panel 20 via the respective optical parts.
[0154] Further, the G-LED 82 is disposed so that after the emergent
light beam therefrom has been collimated by the field lens 52, it
may enter and illuminate the liquid crystal panel 20
perpendicularly thereto with the principal ray g (arrow g in FIG.
21). Also, the emergent light (blue) from the B-LED 81, as
indicated by the principal ray b (arrow b in FIG. 21), illuminates
the liquid crystal panel 20 in a state collimated by the field lens
52, from an oblique direction inclined by an angle .theta.1 in the
x-axis direction with respect to the G light entering the liquid
crystal panel 20 perpendicularly thereto.
[0155] The emergent light (red) from the R-LED 83, as indicated by
the principal ray r (arrow in FIG. 21), emerges at first from a
direction inclined by an angle .theta.2 in the z-axis direction
with respect to the G light, but after it has been reflected by the
mirror 44, it illuminates the liquid crystal panel 20 in a state
collimated by the field lens 52, from an oblique direction inclined
by an angle .theta.2 in the y-axis direction with respect to the G
light entering the liquid crystal panel 20 perpendicularly
thereto.
[0156] The reflected light having polarization-modulated image
information (reflected image light) from the liquid crystal panel
20 has its S-polarized light reflected by the PBS surface 31a of
the PBS 31, whereafter the image thereof is directly observed
through the eyepiece 101 and the iris of an eye 30.
[0157] Accordingly, the focus position at that time is adjusted to
the microlens position in the liquid crystal panel 20, whereby a
modulated good full color view image of identical mixed color
pixels free of mosaic is obtained by a principle entirely similar
to that of the aforedescribed Embodiment 1.
[0158] Also, in the present embodiment, as indicated by arrow Pa in
FIG. 20, external light can be made to come into the eyepiece
through the PBS 31 and therefore, it is possible to endow the
embodiment with the see-through function.
[0159] Now, in the present embodiment as well as in the previous
embodiment, the PBS 31 is used as a polarizing element, but in
order to reduce the cost and weight, use may be made of reflection
type polarizable film such as DBEF produced by 3M Inc. disposed
obliquely so as to correspond to the PBS surface, instead of the
PBS 31. Further, in that case, in order to improve the degree of
polarization (the purity of linear polarization), polarizing plates
may be provided at positions corresponding to the incidence plane
and emergence plane of the PBS 31.
[0160] FIG. 22 is a schematic view of the essential portions of
Embodiment 4 of the projection type liquid crystal display
apparatus of the present invention. In FIG. 22, the reference
numeral 8 designates a lamp emitting a white light beam, the
reference numeral 70 denotes a parabolic reflector, the reference
numeral 45 designates a light intercepting mask with a color filter
having openings comprising R, G and B color filters, and the
reference numeral 53 denotes a condensing lens. The G filter
opening portion 45g of the light intercepting mask 45 is located at
the center of the circular opening of the reflector 70, i.e., on
the optical axis of an illuminating system, the R filter opening
portion 45r of the mask 45 is located upwardly adjacent thereto
(y-direction), and the B filter opening portion 45b of the mask 45
is located rightwardly adjacent thereto (x-direction).
[0161] Also, the condensing lens 53 has its power set so as to
condense parallel light beams emerging from the openings 45g, 45r
and 45b on the liquid crystal panel to be illuminated, as indicated
by arrows r, g and b. However, the green light G from the opening
45g passes on the optical axis and therefore rectilinearly passes
through the lens 53, while the red light R is bent by an angle
.theta.1 in the y-axis direction by the lens 53, and the blue light
B is bent by an angle .theta.2 in the x-axis direction. Here,
.theta.1 and .theta.2 are equal to .theta. described in Embodiment
1.
[0162] Accordingly, by the optical axis of the illuminating system
being designed to extend perpendicularly through the surface of the
liquid crystal panel to be illuminated, the green light G can
illuminate the liquid crystal panel at an angle of incidence which
is perpendicular thereto, the red light R can illuminate the liquid
crystal panel at an angle of incidence inclined by .theta.1 in the
y-axis direction with respect to the perpendicular direction, and
the blue light B can illuminate the liquid crystal panel at an
angle of incidence inclined by .theta.2 in the x-axis direction
with respect to the perpendicular direction, and it becomes
possible to construct a display apparatus using a liquid crystal
panel as in Embodiment 1 or Embodiment 3. According to such an
illuminating system, desired illumination can be effected by a
relatively simple construction.
[0163] FIG. 23 is a cross-sectional view of the essential portions
of Embodiment 5 of the display panel of the present invention. FIG.
23 shows a fragmentary enlarged cross-sectional view of a display
panel 300 using a so-called DMD (deformable mirror device). In FIG.
23, the reference numeral 21 designates a microlens array
substrate, the reference numeral 22 denotes microlenses, the
reference numeral 23 designates sheet glass, the reference numeral
231 denotes a reflection preventing coat layer, the reference
numeral 261 designates pixel electrodes, the reference numeral 271
denotes an active matrix driving circuit portion, and the reference
numeral 281 designates a silicon semiconductor substrate.
[0164] The microlenses 22 are formed on the surface of the glass
substrate 21 formed of alkaline origin glass by the so-called ion
exchange method, and form array structure in which they are
two-dimensionally arranged at a pitch twice as great as the pitch
of the pixel electrodes 261. The pixel electrodes 261 are formed of
aluminum and serve also as reflecting mirrors, and perform a
flexing operation in conformity with a writing-in signal by the
active matrix driving circuit portion 271, as indicated by arrow a
in FIG. 23.
[0165] The active matrix driving circuit portion 271 is a
semiconductor circuit provided on the so-called silicon
semiconductor substrate 281, and serves to active-matrix-drive the
pixel electrodes 261, and gate line drivers (such as vertical
registers) and signal line drivers (such as horizontal registers),
not shown, are provided around this circuit matrix (the details
will be described later).
[0166] These peripheral drivers and the active matrix driving
circuit portion 271 are designed to write R, G and B primary color
image signals into a plurality of R, G and B color pixels, and the
pixel electrodes 261 do not have color filters, but yet are
distinguished as R, G and B color pixels by primary color image
signals written in by the active matrix driving circuit, and form
the same arrangement of R, G and B pixels as that in FIG. 6. Also,
the pitch of the microlenses and the pitch and disposition of the
pixel electrodes and the distance or the like thereof are entirely
similar to those in Embodiment 1.
[0167] Accordingly, when a display apparatus is formed with the
panel of Embodiment 5 combined with the illuminating system as
previously described as in Embodiment 2, the optical paths of R, G
and B color lights as exemplarily shown by G1 and R1 in FIG. 23 are
assumed, whereby identical pixel color mixed display similar to
that in Embodiment 2 becomes possible. Also, as the ray of the
green light G2 indicates, the black display of a certain pixel is
due to the pixel electrodes 261 being flexed, whereby the reflected
light thereof deviates from the openings in the projection lens,
the eyepiece, etc.
[0168] Splendid color image display of high quality free of the
so-called R, G, B mosaic as in the prior art previously described
also becomes possible.
[0169] FIGS. 24A, 24B and 24C are schematic views showing the
construction of Embodiment 6 of the present invention showing a
projection type liquid crystal display apparatus using a
transmission type liquid crystal panel. FIG. 24A is a top plan view
of Embodiment 6, FIG. 24B is a front view thereof, and FIG. 24C is
a side view.
[0170] In FIGS. 24A to 24C, the reference numeral 1 designates a
projection lens, the reference numeral 200 denotes a transmission
type liquid crystal panel with a microlens array, the reference
numeral 40 designates an R reflecting dichroic mirror reflecting
only red light, the reference numeral 41 denotes a B/G reflecting
dichroic mirror reflecting only blue and green lights, the
reference numeral 42 designates a B reflecting dichroic mirror
reflecting only blue light, the reference numeral 43 denotes a high
reflection mirror reflecting all color lights, the reference
numeral 50 designates a Fresnel lens, the reference numeral 51
denotes a convex lens, the reference numeral 6 designates a rod
type integrator, the reference numeral 7 denotes an elliptical
reflector, and the reference numeral 8 designates an arc lamp such
as a metal halide lamp or a UHP.
[0171] Here, the R reflecting dichroic mirror 40, the B/G
reflecting dichroic mirror 41 and the B reflecting dichroic mirror
42 have the spectral reflection characteristics as shown in FIGS.
2A to 2C. These dichroic mirrors, with the high reflection mirror
43, are three-dimensionally disposed like those shown in the
perspective view of FIG. 3, and are adapted to color-resolve white
illuminating light into R, G and B and are designed such that the
primary color lights R, G and B illuminate the liquid crystal panel
three-dimensionally from different directions.
[0172] Describing here in accordance with the travelling process of
the light beam, the white light beam from the lamp 8 is first
condensed on the light incidence surface 6a of the integrator 6
forward of the elliptical reflector 7 by the elliptical reflector
7, and has its cross-sectional light intensity distribution
uniformized as it travels through the integrator 6 while being
repetitively reflected by the inner surface thereof. The light beam
having emerged from the light emergence surface 6b of the
integrator 6 is collimated by the convex lens 51 and the Fresnel
lens 50 and is directed in the x-axis-direction (the reference in
FIG. 24B), and comes to the B reflecting dichroic mirror 42.
[0173] In this B reflecting dichroic mirror 42, only the blue light
B is reflected in the z-axis-direction, i.e., downwardly (the
reference in FIG. 24B) and travels toward the R reflecting dichroic
mirror 40 at a predetermined angle with respect to the z-axis.
[0174] On the other hand, the other red and green lights R/G than
the blue light B pass through the B reflecting dichroic mirror 42
and are reflected at a right angle in the z-axis-direction
(downwardly) by the high reflection mirror 43, and travel toward
the R reflecting dichroic mirror 40. Speaking here on the basis of
FIG. 24A, both of the B reflecting dichroic mirror 42 and the high
reflection mirror 43 are disposed so as to reflect the light beam
(the x-axis-direction) from the integrator 6 in the
z-axis-direction (downwardly), and the high reflection mirror 43
has been rotated by just 45.degree. from the x- and z-axes in x z
plane with its axis parallel to the y-axis as a rotational
axis.
[0175] Also, the B reflecting dichroic mirror 42 is set as having
been rotated by an angle smaller than 45.degree. in x z plane with
its axis parallel to the y-axis as a rotational axis. Accordingly,
the red and green lights R/G reflected by the high reflection
mirror 43 are reflected at a right angle in the z-axis-direction,
whereas the blue light B reflected by the B reflecting dichroic
mirror 42 travels downwardly in a state inclined at a predetermined
angle in x z plane with respect to the z-axis.
[0176] In order to make the illumination ranges of the blue light B
and the red and green lights R/G on the liquid crystal panel 2
coincident with each other, the amounts of shift and the amounts of
tilt of the high reflection mirror 43 and the B reflecting dichroic
mirror 42 are selected so that the principal rays of the respective
color lights may intersect with one another on the liquid crystal
panel 200.
[0177] Next, the three primary color lights R, G and B directed
downwardly (in the z-axis-direction) travel toward the R reflecting
dichroic mirror 40 and the B/G reflecting dichroic mirror 41. These
mirrors 40 and 41 are located under the B reflecting dichroic
mirror 42 and the high reflection mirror 43, and the B/G reflecting
dichroic mirror 41 is inclined by 45.degree. in y z plane with
respect to the y- and z-axes with its axis parallel to the x-axis
as a rotational axis and the R reflecting dichroic mirror 40 is
also set to an angle smaller than 45.degree. in y z plane with its
axis parallel to the x-axis as a rotational axis.
[0178] Accordingly, of the color lights R, G and B entering these
mirrors, the blue and green lights B/G pass through the R
reflecting dichroic mirror 40, are reflected at a right angle in
the y-axis + direction by the B/G reflecting dichroic mirror 41 and
illuminate the liquid crystal panel 2 horizontally disposed in x z
plane. The blue light B, as previously described (see FIGS. 24A and
24B), travels at a predetermined angle (tilted in x z plane) with
respect to the x-axis and therefore, after the reflection by the
B/G reflecting dichroic mirror 41, it maintains a predetermined
angle (tilted in x y plane) with respect to the y-axis, and
illuminates the liquid crystal panel 200 with that angle as the
angle of incidence (the direction of x y plane).
[0179] The green light G is reflected at a right angle by the B/G
reflecting dichroic mirror 41 and travels in the y-axis +
direction, and illuminates the liquid crystal panel 200 at an angle
of incidence of 0.degree., i.e., perpendicularly thereto. Also, the
red light R, as previously described, is reflected in the y-axis +
direction by the R reflecting dichroic mirror 40 disposed short of
the B/G reflecting dichroic mirror 41, but travels in the y-axis +
direction at a predetermined angle (tilted in y z plane) with
respect to the y-axis, as shown in FIG. 24C (a side view), and
illuminates the liquid crystal panel 200 with this angle with
respect to the y-axis as the angle of incidence (the direction of y
z plane).
[0180] Also, in order to make the illumination ranges of the
respective color lights R, G and B on the liquid crystal panel 200
coincident with one another as previously described, the amounts of
shift and the amounts of tilt of the B/G reflecting dichroic mirror
41 and the R reflecting dichroic mirror 40 are selected so that the
principal rays of the respective color lights may intersect with
one another on the liquid crystal panel 200. Further, as shown in
FIGS. 2A, 2B and 2C, the cut wavelength of the B/G reflecting
dichroic mirror 41 is 570 nm and the cut wavelength of the R
reflecting dichroic mirror 40 is 600 nm and therefore, unnecessary
orange-colored light is transmitted through the B/G reflecting
dichroic mirror 41 and discarded. Thereby, optimum color balance
can be obtained.
[0181] As will be described later, the color lights R, G and B are
polarization-modulated by the liquid crystal panel 200 and become
image lights, and travel in the y-axis + direction, and are
enlargedly projected onto a screen (not shown) through the
projection lens 1. Now, the color lights R, G and B illuminating
the liquid crystal panel 200 differ in the angle of incidence onto
the panel from one another and therefore, the lights R, G and B
transmitted therethrough and modulated thereby also differ in the
angle of emergence from the panel from one another and thus, a lens
having a large lens diameter and aperture sufficient to introduce
all of these lights is used as the projection lens 1. However, the
expause of the whole light beam incident on the projection lens 4
is the sam as the expause of the whole light beam when it enters
the liquid crystal panel 200 because each color light passes twice
through the microlens and thereby becomes parallel light.
[0182] However, as shown in FIG. 13, in the transmission type
according to the prior art, the light beam which has emerged from
the liquid crystal panel widens more greatly with the condensing
action of the microlenses also added and therefore, a still greater
numerical aperture has been required of a projection lens for
introducing this light beam thereinto and thus, the projection lens
has become expensive. In the present embodiment, however, the
expause of the whole light beam from the liquid crystal panel 2 is
smaller than in the example of the prior art and therefore, even a
projection lens having a smaller numerical aperture can obtain a
sufficiently bright projected image on the screen and thus, a more
inexpensive projection lens can be used.
[0183] Description will now be made of the liquid crystal panel 200
according to the present invention used here. FIG. 25 shows an
enlarged typical cross-sectional view (corresponding to the y z
plane of FIGS. 24A to 24C) of the liquid crystal panel 200. The
reference numerals 21 and 21' designate microlens substrates, the
reference numerals 22 and 22' denote microlenses, the reference
numerals 23 and 23' designate sheet glass, the reference numeral 24
denotes a transparent opposed electrode, the reference numeral 225
designates a TN liquid crystal layer, the reference numeral 226
denotes transparent pixel electrodes, and the reference numeral 227
designates an active matrix driving circuit portion. The reference
numerals 47 and 46 denote a pair of polarizing plates which are in
a cross nicol relation.
[0184] The microlenses 22 and 22' are formed on the surfaces of the
glass substrates 21 and 21' formed of glass of the alkaline origin
by the so-called ion exchange method, and form array structure in
which they are two-dimensionally arranged at a pitch double the
pitch of the pixel electrodes 226. The sheet glass 23 and 23' is
adhesively secured onto the microlens arrays on the light incidence
and emergence sides. The liquid crystal layer 225 adopts nematic
liquid crystal of the so-called TN mode adapted for the
transmission type, and in a state in which no electric field is
applied thereto, predetermined orientation is maintained by an
oriented layer, not shown. The pixel electrodes 226 comprise TTO
and are formed on the sheet glass 23.
[0185] The active matrix driving circuit portion 227 is a so-called
TFT circuit having so-called amorphous or polysilicon thin film as
a base, and active-matrix-drives the pixel electrodes 226, and is
formed on the sheet glass 23' and has such a layout as shown in
FIG. 29. The reference numerals 301, 302 and 303 designate B, G and
R signal image lines, respectively, the reference numeral 310
denotes a gate line, the reference numerals 321 to 323 designate
TFT's, and the reference characters 226r, 226g and 226b denote R, G
and B transparent pixel electrodes, respectively.
[0186] Also, gate line drivers (such as vertical resisters) and
signal line drivers (such as horizontal registers), not shown, are
provided in the peripheral portion of the circuit matrix (the
details of which will be described later). These peripheral drivers
and the active matrix driving circuit are constructed to write R, G
and B primary color image signals into predetermined respective R,
G and B pixels, and the respective pixel electrodes 226 do not have
color filters, but yet are distinguished as R, G and B pixels by
the primary color image signals written in by the active matrix
driving circuit portion 227, and form a predetermined R, G, B pixel
arrangement which will be described later.
[0187] The green light G illuminating the liquid crystal panel 200
enters the liquid crystal panel 200 perpendicularly thereto as
previously described. Of these rays of light, an example of the
light beam entering a microlens 22a is indicated by arrows G (in)
in FIG. 25. As shown there, this G light beam is condensed by the
microlens and illuminates the G (green) pixel electrode 226g. It
then passes through the liquid crystal layer 225, whereafter it
emerges out of the liquid crystal panel through the microlens 22'a
on the TFT side. When it thus passes through the liquid crystal
layer 225, the green light G having had its linearly polarized
light taken out by the polarizer 46 is subjected to polarization
modulation by the liquid crystal having its oriented state changed
by an electric field formed between the pixel electrode 226g and
the opposed electrode 24 by a signal voltage applied to the pixel
electrode 226g, and emerges from the liquid crystal panel.
[0188] Here, the quantity of the polarized light passing through an
analyzer 47 and travelling toward the projection lens 1 is varied
by the degree of this polarization modulation and thus, so-called
gradation harmony display about the pixels is done. On the other
hand, as described above, the red light R entering from an oblique
direction in a cross-section (y z plane) in the figure also has its
linearly polarized light taken out by the polarizer 46. The red
light beam R entering the microlens 22b, as indicated by arrows R
(in) in FIG. 25, is condensed by the microlens 22b and illuminates
the R (red) pixel electrode 226r at a position downwardly shifted
from right beneath the microlens 22b. It then passes through this R
pixel electrode 226r and as shown, it emerges out of the panel also
through the microlens 22'a on the TFT side (G/R (out)).
[0189] At this time, the red polarized light beam R is subjected to
polarization modulation by the liquid crystal having its oriented
state changed by an electric field formed also between the R pixel
electrode 226r and the opposed electrode 24 by a signal voltage
applied to the R pixel electrode 226r and emerges from the liquid
crystal panel. Thereafter, just as in the case of the
aforedescribed green light G, the red light R becomes image light
which effects the gradation harmony display of the R pixel.
[0190] Now, in FIG. 25, the color lights G and R on the G pixel
electrode 226g and the R pixel electrode 226r, respectively, are
depicted as partly overlapping each other and interfering with each
other, but this is because they are depicted with the thickness of
the liquid crystal layer typically exaggerated, and actually the
thickness of the liquid crystal layer is of the order of 5.mu. at
greatest, and this thickness is very small as compared with the
thickness 50 to 100.mu. of the sheet glass, and independently of
the pixel size, such interference does not occur.
[0191] FIGS. 26A, 26B and 26C show the principle of color
resolution and color combination in the present embodiment. FIG.
26A is a typical top plan view of the liquid crystal panel 200, and
FIGS. 26B and 26C are typical cross-sectional views along the line
26C-26C (x direction) and the line 26B-26B (z direction),
respectively, in FIG. 26A.
[0192] FIG. 26C corresponds to FIG. 25 showing y z cross-section,
and represents the manners of incidence and emergence of the green
light G and the red light R entering the microlenses 22. As can be
seen from this, each G (green) pixel electrode is disposed right
beneath the center of each microlens, and each R (red) pixel
electrode is disposed right beneath the boundary between the
microlenses 22.
[0193] Accordingly, it is preferable to set the angle of incidence
.theta. of the red light R onto the R pixel electrode so that the
tan .theta. thereof may become equal to the ratio between the pixel
pitch of the alternately arranged G and R pixels and the distance
between the microlens and the pixel electrode. On the other hand,
FIG. 26B corresponds to the x y cross-section of the liquid crystal
panel 200. With regard to this x y cross-section, the B (blue)
pixel electrodes and the G (green) pixel electrodes are alternately
disposed as in FIG. 26C, and each G pixel electrode is disposed
right beneath the center of each microlens 22, and each B pixel
electrode is disposed right beneath the boundary between the
microlenses 22.
[0194] Now, the blue light B illuminating the liquid crystal panel
200, as previously described, enters from an oblique direction with
respect to the cross-section (x y plane) in the figure and
therefore, just as in the case of the red light R, the blue light B
having emerged from each microlens 22 passes through the B (blue)
pixel electrode, as shown, and emerges from the microlens (22')
adjacent in x direction to the microlens (22') at a position right
beneath the microlens 22 which the blue light has entered.
[0195] The modulation by the liquid crystal on the B pixel
electrode and the projection of the blue light beam B from the
liquid crystal panel are similar to those of the aforedescribed
green light G and red light R. Also, each B pixel electrode is
disposed right beneath the boundary between the microlenses 22, and
it is preferable that the angle of incidence .theta. of the blue
light B onto the liquid crystal panel be also set so that the tan
.theta. thereof, as in the case of the red light R, may become
equal to the ratio between the pixel pitch of the alternately
arranged G and B pixels and the distance in y-direction between the
microlens and the pixel electrode.
[0196] In the liquid crystal panel described above, the arrangement
of R, G and B color pixels is RGRGRG . . . with respect to
z-direction, and BGBGBG . . . with respect to x-direction. FIG. 26A
shows the planar arrangement thereof.
[0197] As shown in FIG. 26A, the size of each pixel is about a half
of that of each microlens in both length and breadth, i.e., in both
x- and z-directions, and the pitch of the pixels also is a half of
that of the microlenses. Also, each G pixel, also in plane, is
located right beneath the center of each microlens 22, each R pixel
is located at the boundary between the G pixels in z-direction and
between the microlenses arranged in z-direction, and each B pixel
is located at the boundary between the G pixels in x-direction and
between the microlenses arranged in x-direction. Also, the shape of
a microlens unit is a square (the size of a side of which is double
the size of a side of the pixel).
[0198] FIG. 27 is a fragmentary enlarged top plan view of the
liquid crystal panel 200 according to the present embodiment. In
FIG. 27, a broken line lattice 29 indicates an aggregate of three
R, G and B color pixels constituting a picture element. That is,
when the R, G and B pixels are driven by the active matrix driving
circuit portion 227 of FIG. 25, the three R, G and B color pixels
indicated by the broken line lattice 29 are driven by R, G and B
image signals corresponding to the same picture element
position.
[0199] Here, paying attention to a picture element comprising an R
pixel electrode 226r, a G pixel electrode 226g and a B pixel
electrode 226b, the R pixel electrode 262r is illuminated by the
red light R emerging from the microlens 22b and obliquely entering
it, as indicated by arrow r1, and the passing red light R thereof
emerges through a microlens 22'a (not shown) right beneath the
microlens 22a, as indicated by broken line arrow r2. The B pixel
electrode 226b is illuminated by the blue light B emerging from the
microlens 22c and obliquely entering it, as indicated by arrow b1,
and the passing blue light B thereof also emerges through the
microlens 22'a (not shown light beneath the microlens 22a, as
indicated by broken line arrow b2. Also, the G pixel electrode 226g
is illuminated by the green light G entering perpendicularly (in a
direction toward the back of the plane of the drawing sheet) from
the microlens 22a, as indicated by arrow g1 toward the front and
rear, and the transmitted light G thereof also emerges
perpendicularly in a direction toward the back of the plane of the
drawing sheet through the microlens 22'a (not shown) right beneath
the microlens 22a.
[0200] Thus, in the liquid crystal panel according to the present
embodiment, with regard to the R, G and B color pixels constituting
a picture element, the positions of incidence of the three primary
color illuminating lights onto the surface of the microlens array
differ from one another, but the emergence of those lights is
effected from a common microlens (in this case, the microlens
22'a). This also holds true of all the other picture elements (R,
G, B pixel unit).
[0201] Accordingly, if the microlens array of the liquid crystal
panel 200 is adjusted so as to be imaged on the screen 9 when as
shown in FIG. 28, all the emergent lights from the liquid crystal
panel 200 are projected onto the screen 9 or a wall through the
projection lens 1, the projected image becomes one as shown in FIG.
9 wherein a picture element in a state in which the emergent lights
from the R, G, B pixel unit constituting a picture element are
color-mixed, that is, the same pixels are color-mixed, is
constructed in the lattice of microlenses. As in the aforedescribed
plurality of embodiments, good color image display of high quality
free of the so-called R, G, B mosaic becomes possible.
* * * * *