U.S. patent application number 09/750710 was filed with the patent office on 2001-05-10 for optical device, and projection display device including the same.
This patent application is currently assigned to Seiko Epson Corporation. Invention is credited to Haba, Shinji, Takizawa, Takeshi.
Application Number | 20010000972 09/750710 |
Document ID | / |
Family ID | 13192308 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010000972 |
Kind Code |
A1 |
Haba, Shinji ; et
al. |
May 10, 2001 |
Optical device, and projection display device including the
same
Abstract
To increase the usage efficiency of the light of optical
elements used in a projection display device, a polarizing
conversion unit is provided. This polarizing conversion unit
consists of a unit frame, two polarizing conversion element arrays,
a light-shielding plate, a lens array, and clips. From the side of
one open surface of the unit frame, the two polarizing conversion
element arrays are inserted, and the light-shielding plate and the
lens array are inserted from the side of the other open surface in
this order. These optical elements are clamped by four clips from
the two directions of up and down in a state of being stored in the
unit frame. Since the clips are formed of an elastic body, the
clips can be easily attached and detached, and the respective parts
of the polarizing conversion unit can also be easily attached and
detached to and from the unit frame. In addition, these optical
elements may be sequentially inserted from the side of one open
surface.
Inventors: |
Haba, Shinji; (Shiojiri-shi,
JP) ; Takizawa, Takeshi; (Shiojiri-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
Seiko Epson Corporation
|
Family ID: |
13192308 |
Appl. No.: |
09/750710 |
Filed: |
January 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09750710 |
Jan 2, 2001 |
|
|
|
09247531 |
Feb 10, 1999 |
|
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|
6199987 |
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Current U.S.
Class: |
353/34 ;
348/E5.139; 348/E9.027 |
Current CPC
Class: |
G02B 27/285 20130101;
G02F 1/133526 20130101; G02B 27/283 20130101; G02F 1/133308
20130101; G02F 1/133536 20130101; G03B 21/26 20130101; G02F 1/13355
20210101; G02F 1/133548 20210101; G02F 2201/46 20130101; H04N
9/3102 20130101; H04N 5/7416 20130101 |
Class at
Publication: |
353/34 |
International
Class: |
G03B 021/26 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 1998 |
JP |
10-062167 |
Claims
What is claimed is:
1. An optical device, comprising: a lens array having a plurality
of small lenses; a polarizing conversion element array having a
plurality of polarization separating films that separate light
emitted from said small lenses into two kinds of polarized light
and a plurality of reflecting films that reflect one of said two
kinds of polarized light separated by said polarization separating
films, said polarizing conversion element array converting
non-polarized light into one kind of linearly polarized light; and
a jig that detachably incorporates said lens array and said
polarizing conversion element array.
2. The optical device as claimed in claim 1, said lens array and
said polarizing conversion element array having substantially
rectangular outer shapes, said jig including: a frame having a
substantially rectangular first open surface on one side of said
frame and a substantially rectangular second open surface on
another side of said frame, and having a hollow section inside said
frame; a partitioning projection provided on an inner peripheral
surface of said frame that partitions said hollow section into a
first storage section communicating with said first open surface
and second storage section communicating with said second open
surface; fixing members that detachably fix said lens array, said
polarizing conversion element array, and said frame in a state
where said lens array and said polarizing conversion element array
are stored in said frame; and said lens array being stored in said
first storage section from said first open surface and said
polarizing conversion element array being stored in said second
storage section from said second open surface.
3. The optical device as claimed in claim 2, further comprising a
light-shielding plate stored in said frame inserted between said
lens array and said polarizing conversion element array that
shields at least a part of a light incident surface of said
polarizing conversion element array.
4. The optical device as claimed in claim 2, said polarizing
conversion element array being divided into a first array unit and
a second array unit, each having substantially a rectangular outer
shape, and one of said first storage section and said second
storage section in which said first array unit and said second
array unit are stored including: positioning projections provided
between said first array unit and said second array unit that
define positions of said first array unit and said second array
unit; and elastic members provided on opposing inner surfaces of
said frame that press said first array unit and said second array
unit onto said positioning projections, respectively.
5. The optical device as claimed in claim 2, one of said first
storage section and said second storage section in which said lens
array is stored including an elastic member provided on one inner
surface of said frame that presses said lens array onto an opposite
inner surface of said frame.
6. The optical device as claimed in claim 1, said lens array and
said polarizing conversion element array having substantially
rectangular outer shapes, said jig including: a frame having a
substantially rectangular first open surface on one side of said
frame and a substantially rectangular second open surface on
another side of said frame, and having a hollow section inside said
frame; a projection provided close to said first open surface; a
step portion provided on an inner peripheral surface of said frame
that divides said hollow section into a relatively small first
storage section close to said first open surface and a relatively
large second storage section close to said second open surface;
fixing members that detachably fix said lens array, said polarizing
conversion element array, and said frame in a state where said lens
array and said polarizing conversion element array are stored in
said frame; and said lens array and said polarizing conversion
element array being stored in said first storage section and said
second storage section in a predetermined order from said second
open surface.
7. The optical device as claimed in claim 6, further comprising a
light-shielding plate stored in said frame inserted between said
lens array and said polarizing conversion element array that
shields at least a part of a light incident surface of said
polarizing conversion element array.
8. The optical device as claimed in claim 6, said polarizing
conversion element array being divided into a first array unit and
a second array unit, each having substantially a rectangular outer
shape, and one of said first storage section and said second
storage section in which said first array unit and said second
array unit are stored including: positioning projections provided
between said first array unit and said second array unit that
define positions of said first array unit and said second array
unit; and elastic members provided on opposing inner surfaces of
said frame that press said first array unit and said second array
unit onto said positioning projections, respectively.
9. The optical device as claimed in claim 6, said polarizing
conversion element array being divided into first array unit and
second array unit, each having substantially a rectangular outer
shape, one of said first storage section and said second storage
section in which said first array unit and said second array unit
are stored including positioning projections provided between said
first array unit and said second array unit that define positions
of said first array unit and said second array unit, and said first
array unit and said second array unit being pressed onto said
positioning projections by said fixing members.
10. The optical device as claimed in claim 6, one of said first
storage section and said second storage section in which said lens
array is stored including an elastic member provided on one inner
surface of said frame that presses said lens array onto an opposite
inner surface of said frame.
11. A projection display device that projects an image, comprising:
a light source; a first lens array having a plurality of small
lenses; an optical device including a second lens array having a
plurality of small lenses; a polarizing conversion element array
having a plurality of polarization separating films that separate
light emitted from said small lenses into two kinds of polarized
light and a plurality of reflecting films that reflect one of said
two kinds of polarized light separated by said polarization
separating films, said polarizing conversion element array
converting non-polarized light into one kind of linearly polarized
light; and a jig that detachably unites said second lens array and
said polarizing conversion element array; an optical modulation
device that modulates light emitted from said optical device based
on an image signal; and a projection optical system that projects
modulated light emitted from said optical modulation device.
12. The projection display device as claimed in claim 11, said
second lens array and said polarizing conversion element array
having substantially rectangular outer shapes, said jig including:
a frame having a substantially rectangular first open surface on
one side of said frame and a substantially rectangular second open
surface on another side of said frame, and having a hollow section
inside said frame; a partitioning projection provided on an inner
peripheral surface of said frame that partitions said hollow
section into a first storage section communicating with said first
open surface and second storage section communicating with said
second open surface; fixing members that detachably fix said second
lens array, said polarizing conversion element array, and said
frame in a state where said lens array and said polarizing
conversion element array are stored in said frame; and said second
lens array being stored in said first storage section from said
first open surface and said polarizing conversion element array
being stored in said second storage section from said second open
surface.
13. The projection display device as claimed in claim 12, further
comprising a light-shielding plate stored in said frame inserted
between said second lens array and said polarizing conversion
element array that shields at least a part of a light incident
surface of said polarizing conversion element array.
14. The projection display device as claimed in claim 12, said
polarizing conversion element array being divided into a first
array unit and a second array unit, each having substantially a
rectangular outer shape, and one of said first storage section and
said second storage section in which said first array unit and said
second array unit are stored including: positioning projections
provided between said first array unit and said second array unit
that define positions of said first array unit and said second
array unit; and elastic members provided on opposing inner surfaces
of said frame that press said first array unit and said second
array unit onto said positioning projections, respectively.
15. The projection display device as claimed in claim 12, one of
said first storage section and said second storage section in which
said second lens array is stored including an elastic member
provided on one inner surface of said frame that presses said
second lens array onto an opposite inner surface of said frame.
16. The projection display device as claimed in claim 11, said
second lens array and said polarizing conversion element array
having substantially rectangular outer shapes, said jig including:
a frame having a substantially rectangular first open surface on
one side of said frame and a substantially rectangular second open
surface on another side of said frame, and having a hollow section
inside said frame; a projection provided close to said first open
surface; a step portion provided on an inner peripheral surface of
said frame that divides said hollow section into a relatively small
first storage section close to said first open surface and a
relatively large second storage section close to said second open
surface; fixing members that detachably fix said second lens array,
said polarizing conversion element array, and said frame in a state
where said lens array and said polarizing conversion element array
are stored in said frame; and said second lens array and said
polarizing conversion element array being stored in said first
storage section and said second storage section in a predetermined
order from said second open surface.
17. The projection display device as claimed in claim 16, further
comprising a light-shielding plate stored in said frame inserted
between said second lens array and said polarizing conversion
element array that shields at least a part of a light incident
surface of said polarizing conversion element array.
18. The projection display device as claimed in claim 16, said
polarizing conversion element array being divided into a first
array unit and a second array unit, each having substantially a
rectangular outer shape, and one of said first storage section and
said second storage section in which said first array unit and said
second array unit are stored including: positioning projections
provided between said first array unit and said second array unit
that define positions of said first array unit and said second
array unit; and elastic members provided on opposing inner surfaces
of said frame that press said first array unit and said second
array unit onto said positioning projections, respectively.
19. The projection display device as claimed in claim 16, said
polarizing conversion element array being divided into first array
unit and second array unit, each having substantially a rectangular
outer shape, one of said first storage section and said second
storage section in which said first array unit and said second
array unit are stored including positioning projections provided
between said first array unit and said second array unit that
define positions of said first array unit and said second array
unit, and said first array unit and said second array unit being
pressed onto said positioning projections by said fixing
members.
20. The projection display device as claimed in claim 16, one of
said first storage section and said second storage section in which
said second lens array is stored including an elastic member
provided on one inner surface of said frame that presses said
second lens array onto an opposite inner surface of said frame.
21. A projection display device that projects an image, comprising:
a light source; a first lens array having a plurality of small
lenses; an optical device including a second lens array having a
plurality of small lenses; a polarizing conversion element array
having a plurality of polarization separating films that separate
light emitted from said small lenses into two kinds of polarized
light and a plurality of reflecting films that reflect one of said
two kinds of polarized light separated by said polarization
separating films, said polarizing conversion element array
converting non-polarized light into one kind of linearly polarized
light; and a jig that detachably unites said second lens array and
said polarizing conversion element array; a color light separating
optical system that separates light emitted from said optical
device into a plurality of color light; a plurality of optical
modulation devices that respectively modulate said plurality of
color light based on an image signal; a color light synthesizing
section that synthesizes modulated light emitted from said
plurality of optical modulation devices; and a projection optical
system that projects synthesized light emitted from said color
light synthesizing section.
22. The projection display device as claimed in claim 21, said
second lens array and said polarizing conversion element array
having substantially rectangular outer shapes, said jig including:
a frame having a substantially rectangular first open surface on
one side of said frame and a substantially rectangular second open
surface on another side of said frame, and having a hollow section
inside said frame; a partitioning projection provided on an inner
peripheral surface of said frame that partitions said hollow
section into a first storage section communicating with said first
open surface and second storage section communicating with said
second open surface; fixing members that detachably fix said second
lens array, said polarizing conversion element array, and said
frame in a state where said lens array and said polarizing
conversion element array are stored in said frame; and said second
lens array being stored in said first storage section from said
first open surface and said polarizing conversion element array
being stored in said second storage section from said second open
surface.
23. The projection display device as claimed in claim 22, further
comprising a light-shielding plate stored in said frame inserted
between said second lens array and said polarizing conversion
element array that shields at least a part of a light incident
surface of said polarizing conversion element array.
24. The projection display device as claimed in claim 22, said
polarizing conversion element array being divided into a first
array unit and a second array unit, each having substantially a
rectangular outer shape, and one of said first storage section and
said second storage section in which said first array unit and said
second array unit are stored including: positioning projections
provided between said first array unit and said second array unit
that define positions of said first array unit and said second
array unit; and elastic members provided on opposing inner surfaces
of said frame that press said first array unit and said second
array unit onto said positioning projections, respectively.
25. The projection display device as claimed in claim 22, one of
said first storage section and said second storage section in which
said second lens array is stored including an elastic member
provided on one inner surface of said frame that presses said
second lens array onto an opposite inner surface of said frame.
26. The projection display device as claimed in claim 21, said
second lens array and said polarizing conversion element array
having substantially rectangular outer shapes, said jig including:
a frame having a substantially rectangular first open surface on
one side of said frame and a substantially rectangular second open
surface on another side of said frame, and having a hollow section
inside said frame; a projection provided close to said first open
surface; a step portion provided on an inner peripheral surface of
said frame that divides said hollow section into a relatively small
first storage section close to said first open surface and a
relatively large second storage section close to said second open
surface; fixing members that detachably fix said second lens array,
said polarizing conversion element array, and said frame in a state
where said lens array and said polarizing conversion element array
are stored in said frame; and said second lens array and said
polarizing conversion element array being stored in said first
storage section and said second storage section in a predetermined
order from said second open surface.
27. The projection display device as claimed in claim 26, further
comprising a light-shielding plate stored in said frame inserted
between said second lens array and said polarizing conversion
element array that shields at least a part of a light incident
surface of said polarizing conversion element array.
28. The projection display device as claimed in claim 26, said
polarizing conversion element array being divided into a first
array unit and a second array unit, each having substantially a
rectangular outer shape, and one of said first storage section and
said second storage section in which said first array unit and said
second array unit are stored including: positioning projections
provided between said first array unit and said second array unit
that define positions of said first array unit and said second
array unit; and elastic members provided on opposing inner surfaces
of said frame that press said first array unit and said second
array unit onto said positioning projections, respectively.
29. The projection display device as claimed in claim 26, said
polarizing conversion element array being divided into first array
unit and second array unit, each having substantially a rectangular
outer shape, one of said first storage section and said second
storage section in which said first array unit and said second
array unit are stored including positioning projections provided
between said first array unit and said second array unit that
define positions of said first array unit and said second array
unit, and said first array unit and said second array unit being
pressed onto said positioning projections by said fixing
members.
30. The projection display device as claimed in claim 26, one of
said first storage section and said second storage section in which
said second lens array is stored including an elastic member
provided on one inner surface of said frame that presses said
second lens array onto an opposite inner surface of said frame.
Description
BACKGROUND OF THE INVENTION
1. 1. Field of Invention
2. This invention relates to an optical device incorporating a
plurality of optical parts (elements), and to a projection display
device including this optical device.
3. 2. Description of Related Art
4. In a projection display device, in order to increase the usage
efficiency of light and obtain a bright projected image, a
polarized light illumination optical system and an integrator
optical system are utilized. The polarized light illumination
optical system is an optical system which utilizes only polarized
light having one polarization direction as illuminating light. In
this polarized light illumination optical system, a polarizing
conversion element for converting non-polarized light (light having
random polarization directions) into light having one polarization
direction is employed. In addition, the integrator optical system
is an optical system which divides light source light into a
plurality of fine partial luminous fluxes, and which utilizes the
respective partial luminous fluxes as illuminating light. In this
integrator optical system, a lens array that includes a plurality
of small lenses and that divides light source light into a
plurality of partial luminous fluxes is employed. An illumination
optical system is normally constructed by a combination of the
polarized light illumination optical system and the integrator
optical system.
SUMMARY OF THE INVENTION
5. Hitherto, respective optical parts used in the projection
display device have been mounted in guides provided at respective
predetermined positions on a chassis for mounting respective
components of a projection display device thereon. Therefore, the
relative positional accuracy of the respective optical components
greatly depends on the relative positional accuracy of the
respective guides provided on the chassis. Since the chassis is
intended for mounting the respective components employed in the
projection display device thereon, a certain large size is
required, and the positional accuracy of the respective guides
provided on the chassis is not very good. However, in order to
increase the usage efficiency of the light by bringing out the
functions of the polarized light illumination optical system and
the integrator optical system, it is preferable to improve the
relative positional accuracy when the optical parts used in these
systems, especially, the polarizing conversion element and the lens
array mounted on the chassis.
6. This invention is made to solve the above problem in the
conventional art, and an object is to provide a technique for
increasing the usage efficiency of the light of optical elements
used in a projection display device.
7. In order to solve at least a part of the above problem, an
optical device of the present invention includes:
8. a lens array having a plurality of small lenses;
9. a polarizing conversion element array having a plurality of
polarization separating films that separate light emitted from the
small lenses into two kinds of polarized light and a plurality of
reflecting films that reflect one of the two kinds of polarized
light separated by the polarization separating films, the
polarizing conversion element array converting non-polarized light
into one kind of linearly polarized light; and
10. a jig that detachably incorporates the lens array and the
polarizing conversion element array.
11. This optical device can detachably combine the lens array and
the polarizing conversion element array in one. This can improve
the relative positional accuracy of the optical parts (elements)
included in this optical device. This can increase the usage
efficiency of the light of the optical elements included in this
optical device. In addition, since the optical device of the
present invention is detachable, the optical elements incorporated
into this optical device can easily be exchanged.
12. Here, in the above optical device, it is preferable that the
lens array and the polarizing conversion element array have
substantially rectangular outer shapes,
13. that the jig includes:
14. a frame having substantially a rectangular first open surface
and a rectangular second open surface on two sides of the frame,
and having a hollow section inside the frame;
15. a partitioning projection provided on an inner peripheral
surface of the frame that partitions the hollow section into a
first storage section and a second storage section communicating
with the first open surface and the second open surface;
16. fixing members that detachably fix the lens array, the
polarizing conversion element array, and the frame in a state where
the lens array and the polarizing conversion element array are
stored in the frame; and
17. that the lens array and the polarizing conversion element array
are stored in the first storage section and the second storage
section, respectively, from the first open surface and the second
open surface.
18. According to the above jig, since the lens array can be stored
in the first storage section from the first open surface, and the
polarizing conversion element array can be stored in the second
storage section from the second open surface, even if one of the
optical element is required to be exchanged, it can be exchanged
without removing the other optical element. Therefore, there is the
advantage of easy exchange of the parts.
19. In addition, in the above optical device, it is also preferable
that the lens array and the polarizing conversion element array
have substantially rectangular outer shapes,
20. that the jig includes:
21. a frame having substantially a rectangular first open surface
and a rectangular second open surface on two sides of the frame,
and having a hollow section inside the frame;
22. a projection provided close to the first open surface;
23. a step portion provided on an inner peripheral surface of the
frame that divides the hollow section into a relatively small first
storage section close to the first open surface and a relatively
large second storage section close to the second open surface;
24. fixing members that detachably fix the lens array, the
polarizing conversion element array, and the frame in a state where
the lens array and the polarizing conversion element array are
stored in said frame; and
25. that the lens array and the polarizing conversion element array
are stored in the first storage section and the second storage
section in a predetermined order from the second open surface.
26. According to the above jig, the lens array and the polarizing
conversion element array can be stored in the first storage section
and the second storage section in a predetermined order from the
second open surface. Therefore, there is the advantage of easy
assembly.
27. Incidentally, the above respective optical devices may consist
of a light-shielding plate stored in the frame inserted between the
lens array and the polarizing conversion element array that shields
at least a part of a light incident surface of the polarizing
conversion element array.
28. By shielding at least a part of a light incident surface of the
polarizing conversion element array, the purity (degree of
polarization) of one kind of linearly polarized light emitted from
the polarizing conversion element can be increased.
29. In addition, in the above respective optical devices, it is
preferable that the polarizing conversion element array is divided
into a first array unit and a second array unit, each having
substantially a rectangular outer shape, and that one of the first
storage section and the second storage section in which the first
array unit and the second array unit are stored includes:
positioning projections provided between the first array unit and
the second array unit that define positions of the first array unit
and the second array unit; and elastic members provided on opposing
inner surfaces of the frame to press the first array unit and the
second array unit onto the positioning projections,
respectively.
30. In addition, in the above optical device, when the lens array
and the polarizing conversion element array are stored in the first
storage section and the second storage section in a predetermined
order from the second open surface, the polarizing conversion
element array may be divided into first array unit and second array
unit, each having substantially a rectangular outer shape,
31. one of the first storage section and the second storage section
in which the first array unit and the second array unit are stored
may include positioning projections provided between the first
array unit and the second array unit that define positions of the
first array unit and the second array unit, and
32. the first array unit and the second array unit may be pressed
onto the positioning projections by the fixing members.
33. According to the above arrangements, when the polarizing
conversion element array is divided into the first array unit and
the second array unit, the first array unit and the second array
unit can be accurately stored with reference to the positioning
projections.
34. Furthermore, in the above respective optical devices, one of
the first storage section and the second storage section in which
the lens array is stored may preferably include an elastic member
used for the lens array provided on one inner surface of the frame
to press the lens array onto an opposite inner surface of the
frame.
35. According to the above arrangement, since the lens array is
pressed onto the inner surface of the frame opposite to the inner
surface onto which the elastic member used for the lens array is
bonded, the lens array can be accurately stored with reference to
this opposite inner surface.
36. A first projection display device of the present invention
includes:
37. a light source;
38. a first lens array having a plurality of small lenses;
39. an optical device including a second lens array corresponding
to the first lens array; a polarizing conversion element array
having a plurality of polarization separating films that separate
light emitted from the small lenses into two kinds of polarized
light and a plurality of reflecting films that reflect one of the
two kinds of polarized light separated by the polarization
separating films, the polarizing conversion element array
converting non-polarized light into one kind of linearly polarized
light; and a jig that detachably unites the second lens array and
the polarizing conversion element array;
40. a color light separation optical system that separates light
emitted from the optical device into a plurality of color
light;
41. a plurality of optical modulation devices that respectively
modulate the plurality of color light based on an image signal;
42. a color light synthesizing section that synthesizes modulated
light emitted from the plurality of optical modulation devices;
and
43. a projection optical system that projects synthesized light
emitted from the color light synthesizing section.
44. By employing the optical device of the present invention for
the above first and second projection display devices, the usage
efficiency of the light of the projection display devices can be
increased. In addition, since the optical elements included in this
optical device are easily detachable, the parts included in this
optical device can easily be exchanged.
BRIEF DESCRIPTION OF THE DRAWINGS
45. FIG. 1 is an illustration which schematically shows a
construction of a polarized light illumination optical system that
is applied to a projection display device.
46. FIGS. 2(A)-(B) include a front view and a side view each
showing the external appearance of a first lens array 20.
47. FIG. 3 is a perspective view showing the external appearance of
a polarizing conversion element array 131.
48. FIG. 4 is an illustration showing the function of the
polarizing conversion element array 131.
49. FIG. 5 is a plan view of a light-shielding plate 140.
50. FIGS. 6(A)-(C) are illustrations showing the external
appearance of an optical device as a first embodiment of the
present invention.
51. FIG. 7 is an exploded perspective view of the optical device as
the first embodiment of the present invention.
52. FIGS. 8(A)-(B) are illustrations showing the external
appearance of a unit frame 100 for assembling a polarizing
conversion unit 30.
53. FIGS. 9(A)-(B) are schematic cross-sectional views showing a
state in which the polarizing conversion unit 30 is incorporated
into the projection display device.
54. FIGS. 10(A)-(F) are illustrations showing the external
appearance of an optical device as a second embodiment of the
present invention.
55. FIG. 11 is an exploded perspective view of the optical device
as the second embodiment of the present invention.
56. FIGS. 12(A)-(G) are illustrations showing the external
appearance of a unit frame 500 for assembling a polarizing
conversion unit 30A.
57. FIG. 13 is a schematic plan view showing the construction of a
projection display device incorporating the optical device of the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
58. Next, the mode for carrying out the present invention will be
described on the basis of embodiments. Incidentally, in the
following explanation, unless otherwise specified, the direction in
which light travels is referred to as the z direction, the
direction of 12 o'clock as viewed from the z direction is referred
to as the y direction, and the direction of 3 o'clock is referred
to as the x direction. In addition, a surface of an optical part as
viewed from the z direction is referred to as a front surface, and
a surface as viewed from the y direction is referred to as a top
surface, and a description will be given by referring to the front
view, in general.
A. First Embodiment
59. FIG. 1 is an illustration which schematically shows a
construction of a polarized light illumination optical system that
is applied to a projection display device. This illumination
optical system is an integrator illumination optical system
consisting of a light source 10, a first lens array 20, a second
lens array 150, a light-shielding plate 140, two polarizing
conversion element arrays 131 and 132, and a superimposing lens 40.
As described later, the second lens array 150, the light-shielding
plate 140, and the two polarizing conversion element arrays 131 and
132 are combined as one polarizing conversion unit (optical device)
30.
60. FIGS. 2(A)-(B) include a front view and a side view, each
showing the external appearance of the first lens array 20. The
first lens array 20 has a construction such that minute and small
lenses 201 each having a rectangular outline are arranged in the
form of a matrix with M rows in the vertical direction and 2N
columns in the lateral direction. Therefore, from the center of the
lens in the lateral direction, the lenses are present in N columns
leftward and in N columns rightward. In this example, M=10, and
N=4. The second lens array 150 is a lens array having a
configuration similar to that of the first lens array 20.
Incidentally, the first lens array 20 and the second lens array 150
may face in either the +z direction or -z direction. In addition,
as shown in FIG. 1, they may face different directions from each
other.
61. FIG. 3 is a perspective view showing the external appearance of
a polarizing conversion element array 131. This polarizing
conversion element array 131 consists of a polarizing beam splitter
array 320 and .lambda./2 phase layers 381 arranged selectively at a
part of the light emitting surface of the polarizing beam splitter
array 320 (shown by oblique lines). The polarizing beam splitter
array 320 has a shape such that a plurality of columnar
transmissive plates 323, each having the shape of parallelogram in
cross section, are bonded sequentially. On the interfaces of the
transmissive plates 323, polarization separating films 331 and
reflecting films 332 are alternately formed. The .lambda./2 phase
layers 381 are selectively bonded onto image portions in the x
direction of light emitting surfaces of the polarization separating
films 331 or the reflecting films 332. In this example, the
.lambda./2 phase layers 381 are bonded onto the image portions in
the x direction of the light emitting surfaces of the polarization
separating films 331.
62. The polarizing conversion element array 131 has the function of
converting and emitting incident luminous fluxes into one kind of
linearly polarized light (for example, s-polarized light or
p-polarized light). FIG. 4 is an illustration showing the function
of the polarizing conversion element array 131. Non-polarized light
(incident light having random polarization directions) including an
s-polarized light component and a p-polarized light component is
incident on an incident surface of a polarizing conversion element.
This incident light is first separated into s-polarization light
and p-polarization light by the polarization separating film 331.
The s-polarized light is reflected almost perpendicularly by the
polarization separating film 331, and emitted after being further
reflected perpendicularly by the reflecting film 332. On the other
hand, the p-polarized light is transmitted through the polarization
separating film 331 as is. The .lambda./2 phase layer 381 is
arranged on the emitting surface of the p-polarized light
transmitted through the polarization separating film, and this
p-polarized light is converted into s-polarized light and then is
emitted. Therefore, almost all of the light passing through the
polarizing conversion element is emitted as s-polarized light. In
addition, when the light emitted from the polarizing conversion
element is to be converted into p-polarized light, the .lambda./2
phase layer 381 may be arranged on an emitting surface from which
the s-polarized light reflected by the reflecting film 332 is
emitted.
63. Incidentally, one polarization separating film 331 and one
reflecting film 332 that are adjacent to each other and one
.lambda./2 phase layer 381 may together form a block which may be
regarded as one polarizing conversion element 325. The polarizing
conversion element array 131 has such polarizing conversion
elements 325 arranged in a plurality of columns in the x direction.
In this embodiment, the polarizing conversion element array 131 is
formed by 4 columns of polarizing conversion elements 325.
64. Since the polarizing conversion element array 132 is exactly
the same as the polarizing conversion element array 131, an
explanation thereof is omitted.
65. The two polarizing conversion element arrays 131 and 132 are,
as shown in FIG. 1, arranged symmetrically with respect to an
optical axis of the illumination optical system.
66. FIG. 5 is a plan view of the light-shielding plate 140. The
light-shielding plate 140 has a construction such that openings 141
are formed in a substantially rectangular plate member so that of
the light incident surfaces of the two polarizing conversion
element arrays 131 and 132, light is incident only on the light
incident surface corresponding to the polarization separating film
331.
67. The non-polarized light emitted from the light source 10 shown
in FIG. 1 is divided into a plurality of partial luminous fluxes
202 by a plurality of small lenses of the first lens array 20 and
the second lens array 150, and is collected in the vicinity of the
polarization separating films 331 of the two polarizing conversion
element arrays 131 and 132. In particular, the second lens array
150 has the function of guiding a plurality of partial luminous
fluxes emitted from the first lens array 20 so as to be collected
on the polarization separating films 331 of the two polarizing
conversion element arrays 131 and 132. The plurality of partial
luminous fluxes incident on the two polarizing conversion element
arrays 131 and 132 are converted into one kind of linearly
polarized light and then are emitted, as described above. The
plurality of partial luminous fluxes emitted from the two
polarizing conversion element arrays 131 and 132 are superimposed
on a predetermined illumination area 80 by the superimposing lens
40. This allows the illumination optical system to uniformly
illuminate a predetermined illumination area.
68. As is understood from the foregoing explanation, in this
illumination optical system, the second lens array 150, the
light-shielding plate 140, and the two polarizing conversion
element arrays 131 and 132 are important optical elements for
efficiently converting the light emitted from a light source into
one kind of linearly polarized light. Therefore, it is preferable
to precisely arrange these optical elements. Thus, the polarizing
conversion unit 30 of the present invention assembles these second
lens array 150, light-shielding plate 140, and two polarizing
conversion element arrays 131 and 132 together for the precise
arrangement.
69. FIGS. 6(A)-(C) are illustrations showing the external
appearance of a polarizing conversion unit (optical device) as the
first embodiment of the present invention. FIG. 7 is an exploded
perspective view of this polarizing conversion unit. This
polarizing conversion unit 30 consists of a unit frame 100, two
polarizing conversion element arrays 131 and 132, a light-shielding
plate 140, a lens array 150, and clips 160. From the side of one
open surface (lower surface in FIG. 7) of the unit frame 100, the
two polarizing conversion element arrays 131 and 132 are inserted,
and the light-shielding plate 140 and the lens array 150 are
inserted from the side of the other open surface (top surface in
FIG. 7) in this order. These optical elements 131, 132, 140, and
150 are clamped by four clips 160 from the two directions of up and
down in a state of being stored in the unit frame 100. Since the
clips 160 are formed of an elastic body, the clips 160 can be
easily attached and detached, and the respective parts of the
optical device 30 can also be easily attached and detached to and
from the unit frame.
70. FIGS. 8(A)-(G) are illustrations showing the external
appearance of the unit frame 100 for assembling the polarizing
conversion unit 30. FIG. 8(A) shows a front view, FIG. 8(B) shows a
top view, FIG. 8(C) shows a bottom view, FIG. 8(D) shows a left
side view, FIG. 8(E) shows a right side view, FIG. 8(F) shows a
rear view, and FIG. 8(G) shows a cross-sectional view taken along
AA' of FIG. 8(F). Incidentally, the front surface shows a light
emitting surface, and the rear surface shows a light incident
surface. As shown in FIG. 8(G), the unit frame 100 has
substantially an H shape in cross section, and has a recess 102 on
the side of the light emitting surface (front surface) and a recess
112 on the side of the light incident surface (rear surface). The
unit frame 100 is made by, for example, a resin molding.
71. The unit frame 100 has the substantially rectangular recess 102
on the side of the light emitting surface, as shown in FIGS. 8(A)
and 8(G). This recess 102 functions as a storage section for
storing the two polarizing conversion element arrays 131 and 132. A
partition 102b for partitioning a hollow section of the unit frame
100 into the recess 102 on the side of the light emitting surface
and the recess 112 on the side of the light incident surface is
provided on the inner surface of the recess 102, and the partition
102b has an opening 102a in the center thereof.
72. As shown in FIG. 8(A), projections 104 each having
substantially the shape of a rectangular parallelepiped are
provided on the center positions of the upper and lower inner
surfaces of the recess 102 on the side of the light emitting
surface, and small grooves 106 are provided on the two sides of
each of the projections 104. In addition, grooves 108 are also
provided on the left and right inner surfaces of the recess 102,
and cushion materials 110 thicker than the grooves 108 are bonded
to the grooves 108. The cushion materials 110 slightly project
inward from the left and right inner surfaces of the recess 102. As
shown in FIG. 6(C), the two polarizing conversion element arrays
131 and 132 are inserted into the recess 102 in such a manner that
they sandwich the projections 104. At this time, the two polarizing
conversion element arrays 131 and 132 are pressed toward the inside
by the cushion materials 110, and are arranged on both left and
right sides with reference to the projections 104. Therefore, a gap
between the two polarizing conversion element arrays 131 and 132 is
defined by the thickness of the projections 104. As the cushion
materials, an elastic material such as porous rubber may be
employed. Incidentally, the grooves 106 (FIG. 8(A)) provided on
both sides of each of the projections 104 are provided so that,
even if roots of the projections 104 protrude, the two polarizing
conversion element arrays 131 and 132 do not contact the protruded
portions.
73. As will be understood from FIG. 7, the two polarizing
conversion element arrays 131 and 132 are stored in the recess 102
so that they face in opposite direction from each other across the
projections 104, and the sides of the emitting surfaces of the
polarizing conversion element arrays 131 and 132 (the side of the
surface shown in FIG. 3 onto which the .lambda./2 phase layers 381
are bonded) face outward. Incidentally, in order not to mistake the
direction of insertion of the polarizing conversion element arrays
131 and 132, the outermost transmissive member constituting the
polarizing conversion element arrays 131 and 132 may be preferably
colored in a color different from that of the other transmissive
members. For example, the outermost transmissive member may be a
blue plate glass, and the other transmissive members may be white
plate glasses. In addition, it is effective to provide a notch as a
mark on the outermost transmissive member.
74. On the side of the light incident surface of the unit frame
100, a substantially rectangular recess 112a slightly smaller than
the outer shape of the substantially rectangular unit frame 100 is
formed, as shown in FIGS. 8(F) and 8(G). Furthermore, a step
portion is provided on the bottom of the recess 112a, whereby a
recess 112b even more slightly smaller than the recess 112a is
formed. This recess 112b is partitioned from the recess 102 by the
partition 102b.
75. This recess 112b is a storage section for storing the
above-described light-shielding plate 140. Since the recess 112b
has a size substantially the same as that of the light-shielding
plate 140, by inserting the light-shielding plate 140 into this
recess 112b, the light-shielding plate 140 can be accurately
arranged with respect to the two polarizing conversion element
arrays 131 and 132.
76. The recess 112a is a storage section for storing the lens array
150. As shown in FIG. 8(F), two projections 116 are provided on the
right inner surface of the recess 112a for the positioning of the
lens array 150. In addition, the cushion material 110 is bonded
onto the left inner surface. When inserting the lens array 150, the
lens array 150 is inserted into the recess 112a in such a manner as
to press the cushion material 110 leftward. The lens array 150 is
pressed by the cushion material 110 in the direction of the
projections 116, and is accurately arranged in a lateral direction
with reference to the projections 116.
77. At both left-hand upper and lower ends and right-hand upper and
lower ends on the side of the front surface of the unit frame 100,
projection-like clipping portions 118 are provided, as shown in
FIGS. 8(A) to 8(E). Each of the clips 160 having substantially a U
shape (FIG. 7) and a hole 162 corresponding to the clipping portion
118 is provided therein. By these clips 160, the two polarizing
conversion element arrays 131 and 132 inserted into the unit frame
100 and the lens array 150 can be sandwiched from both sides and
fixed to the unit frame 100.
78. Three projections 120 are formed on the top surface of the unit
frame 100, as will be understood from FIGS. 8(A) and 8(B). In
addition, on the left and right outer frames of the unit frame 100,
guide insertion portions 122 that are inserted into holding grooves
(to be described later) in the projection display device are
provided. On the side of the light emitting surface (front) of
these guide insertion portions 122, the cushion materials 110 are
bonded. FIGS. 9(A)-(B) are schematic sectional views showing a
state in which the polarizing conversion unit 30 is incorporated in
the projection display device. FIG. 9(B) shows a schematic
cross-sectional view taken along BB' of FIG. 9(A). The optical
parts (elements) to be incorporated into the projection display
device are normally sandwiched and incorporated by a chassis 600D
called a lower light guide, and a cover 600U called an upper light
guide. The upper and lower light guides 600U and 600D form a pair
of left and right vertical walls 911 and 912 vertically extending
along the plane perpendicular to the optical axis LC, a bottom wall
913 connecting lower ends of these vertical walls 911 and 912, and
an upper wall 914 connecting upper ends of these vertical walls 911
and 912. The polarizing conversion unit 30 is arranged in a portion
surrounded by the respective walls 911 to 914. On both the left and
right side walls 911 and 912, holding grooves 915 are provided. The
polarizing conversion unit 30 is incorporated by inserting left and
right guide insertion portions 122 into these holding grooves 915.
Since the cushion materials 110 are bonded on the front surface
side of the guide insertion portions 122, as described above, the
guide insertion portions 122 are pressed to the side of the rear
surface by the cushion materials 110, whereby the polarizing
conversion unit 30 can be fixed with reference to surfaces of the
holding grooves 915 contacting the rear surfaces of the guide
insertion portions 122.
79. The projections 120 provided on the top surface of the unit
frame 100 are intended for pressing the upper wall 914, as shown in
FIG. 9(A). This can prevent the polarizing conversion unit 30 from
rattling up and down. In addition, the lower light guide 600D is
provided with a ventilation opening (not shown). Cooling air fed
through the ventilation opening flows along the plane of the
polarizing conversion unit 30, and is exhausted after flowing
between the projections 120 and the upper light guide 600U. This
can cool the polarizing conversion unit 30 with efficiency.
80. As described above, the two polarizing conversion element
arrays 131 and 132 are inserted from the side of one open surface
of the unit frame 100, the light-shielding plate 140 and the lens
array 150 are sequentially inserted from the side of the other open
surface, whereby the polarizing conversion unit 30 combined in one
piece can be constructed (FIG. 7). This can accurately arrange the
respective components in relation to each other, and increase the
usage efficiency of the light. In addition, this polarizing
conversion unit 30 has a simple structure such that the respective
components 131, 132, 140, and 150 are inserted into the unit frame
100 and are merely fixed by the clips 160, so that the polarizing
conversion unit 30 can be easily attached and detached. This allows
the respective components to be easily exchanged.
81. Incidentally, projections similar to the projections 104 shown
in FIG. 8(A) may be formed in the centers of upper and lower inner
surfaces of the recess 112b. At this time, grooves corresponding to
these projections may be provided in the centers of upper and lower
ends of the light-shielding plate 140. Conversely, grooves may be
provided in the centers of upper and lower inner surfaces of the
recess 112b, and projections corresponding to the light-shielding
plate 140 may be provided. This allows the light-shielding plate
140 to be arranged with reference to the center projections,
similarly to the two polarizing conversion element arrays 131 and
132.
82. In addition, projections similar to the projections 104 may
also be provided in the centers of the upper and lower inner
surfaces of the recess 112a. At this time, grooves corresponding to
these projections may be provided in the centers of upper and lower
ends of the lens array 150. Conversely, grooves may be provided in
the centers of upper and lower side surface of the recess 112a, and
projections corresponding to these grooves may be provided on the
lens array 150. This allows the lens array 150 to be arranged with
reference to the center projections, similarly to the two
polarizing conversion element arrays 131 and 132.
83. Furthermore, the two polarizing conversion element arrays 131
and 132 may be united in one polarizing conversion element array.
At this time, the direction of the polarization separating film 331
and the reflecting film 332 may not be symmetrical with respect to
the center, but be parallel to each other. When one polarizing
conversion element array is employed, a projection is provided on
the right or left inner surface of the recess 102, and the cushion
material may be bonded onto the inner surface of the side opposite
thereto, similarly to the recess 112a. This allows the polarizing
conversion element array to be arranged with reference to the
projection provided on the right or left inner surface.
B. Second Embodiment
84. FIGS. 10(A)-(F) are illustrations showing the external
appearance of a polarizing conversion unit (optical device) as a
second embodiment of the present invention. FIG. 11 is an exploded
perspective view of this polarizing conversion unit. As shown in
FIG. 11, this polarizing conversion unit 30A consists of a unit
frame 500, a lens array 550, a light-shielding plate 540, and two
polarizing conversion element arrays 531 and 532. From the side of
one open surface (top surface in FIG. 11) of the unit frame 500,
the lens array 550, the light-shielding plate 540, and the two
polarizing conversion element arrays 531 and 532 are sequentially
inserted. These optical elements 531, 532, 540, and 550 are clamped
by a clip 560 from the three directions of above, left and right in
a state of being stored in the unit frame 500. The clip 560 has
first connecting portions 562 for laterally connecting engagement
portions 561, each engagement portion 561 having substantially a U
shape that is caught by projections 512 provided at four corners of
the unit frame 500, and second connecting portions 563 for
vertically connecting the engagement portions 561. Since the clip
560 is formed of an elastic body, the clip 560 can be easily
attached and detached, and the respective components of the optical
device 30A can also be easily attached and detached to and from the
unit frame.
85. The lens array 550, light-shielding plate 540 and the
polarizing conversion element arrays 531 and 532 have the same
functions as those of the lens array 150, light-shielding plate 140
and polarizing conversion element arrays 131 and 132 in the first
example, respectively. The polarizing conversion element arrays 531
and 532, shown in FIG. 11, are constructed by three columns of
polarizing conversion elements 350, the lens array 550 is
constructed by 8 rows and 6 columns corresponding thereto, and an
opening of the light-shielding plate 540 is also formed
corresponding thereto. The constructions of the respective optical
elements merely show an example, and they may be similar to those
of the first embodiment. Incidentally, an explanation of the
functions of the respective optical elements is omitted.
86. FIGS. 12(A)-(G) are illustrations showing the external
appearance of the unit frame 500 for assembling the polarizing
conversion unit 30A. FIG. 12(A) shows a front view, FIG. 12(B)
shows a top view, FIG. 12(C) shows a bottom view, FIG. 12(D) shows
a left side view, FIG. 12(E) shows a right side view, FIG. 12(F)
shows a rear view, and FIG. 12(G) shows a cross-sectional view
taken along CC' of FIG. 12(A). Incidentally, similarly to FIGS.
8(A)-(G), the front surface shows a light emitting surface, and the
rear surface shows a light incident surface.
87. The unit frame 500 has a substantially rectangular recess 502a
on the side of the light emitting surface, as shown in FIG. 12(G).
Furthermore, a step portion is provided on the bottom of the recess
502a, whereby a recess 502b even more slightly smaller than the
recess 502a is formed. The bottom of this recess 502b functions as
a partition 504b for partitioning the recess 502b and the light
incident surface side. The partition 504b has an opening 504a
formed in the center thereof. This opening 504a corresponds to the
light incident surface of the polarizing conversion unit 30A.
88. The lower recess 502b of FIG. 12(G) is a storage section for
storing the lens array 550. As shown in FIG. 12(A), two projections
506 are respectively provided on the right and lower inner surfaces
of the recess 502b for the positioning of the lens array 550. In
addition, a cushion material 110 is bent and bonded from the
leftward upper end to the upward left end of the recess 502b. By
inserting the lens array 550 into the recess 502b in such a manner
as to press an upper left corner of the lens array 550 to the
cushion material 110, the lens array 550 is pressed downward and
rightward by the cushion material 110, and is accurately arranged
in the lateral and vertical directions with reference to the right
and lower projections 506. Incidentally, spacers 551 are bonded to
the upper and lower ends of the lens array 550 on the side of the
light-shielding plate for providing a space between the
light-shielding plate 540 and the lens array 550, as shown in FIG.
11.
89. The recess 502a is a storage section for storing the
light-shielding plate 540 and the two polarizing conversion element
arrays 531 and 532. As shown in FIG. 12(A), projections 508, each
having substantially the shape of a rectangular parallelepiped, are
provided on the center positions of the upper and lower inner
surfaces of the recess 502a. In addition, grooves 510 similar to
the grooves 106 provided on both sides of each of the projections
104 in the first embodiment are provided on the two sides of each
of the projections 508. Furthermore, clipping portions 512 are
provided on both upper and lower portions of the left and right
outer side surfaces of the unit frame 500.
90. The light-shielding plate 540 is provided with grooves 541,
which correspond to the projections 508, on the upper and lower
central ends, as shown in FIG. 11. The light-shielding plate 540 is
inserted into the recess 502a in such a manner that the projections
508 fit into the grooves 541 of the light-shielding plate 540. This
allows the light-shielding plate 540 to be accurately arranged in
the recess 502a with reference to the projections 508.
91. To the upper (light emitting surface) side of the
light-shielding plate 540 of the recess 502a, the two polarizing
conversion element arrays 531 and 532 are further inserted in such
a manner that they sandwich the projections 508, as shown in FIG.
11. Thereafter, holes of the engagement portions 561 of four
corners of the clip 560 are fitted to the clipping projections 512
of the unit frame 500 while the polarizing conversion element
arrays 531 and 532 are pressed downward by the upper and lower
connecting portions 562 of the clip 560, whereby the respective
components 550, 540, 531, and 532 are fixed to the unit frame 500.
Since the clip 560 is formed of an elastic body (plate spring), the
two polarizing conversion element arrays 531 and 532 are pressed
from the light emitting surface to the direction of the light
incident surface by the clip 560, and are fixed in a state of being
pressed from the left side surface and right side surface to the
direction of the projections 508. This allows the polarizing
conversion element arrays 531 and 532 to be accurately arranged on
both left and right sides with reference to the projections 508. In
addition, the respective components (parts) of the polarizing
conversion unit 30A can be fixed in the unit frame 500. A gap
between the two polarizing conversion element arrays 531 and 532 is
defined by the thickness of the projections 508, similarly to the
first embodiment.
92. On the left and right side surfaces of the unit frame 500,
guide insertion portions 522 to be inserted into holding grooves in
the projection display device are provided. On the side of the
front surfaces of these guide insertion portions 522, the cushion
materials 110 are bonded. This allows the polarizing conversion
unit 30A to be fixed with reference to surfaces of the holding
grooves contacting the rear surfaces of the guide insertion
portions 522, just as described in the first embodiment.
93. As described above, in the second embodiment, the lens array
550, the light-shielding plate 540 and two polarizing conversion
element arrays 531 and 532 are sequentially inserted from the side
of one open surface of the unit frame 500, whereby the polarizing
conversion unit 30A combined in one piece can be constructed (FIG.
11). This can accurately arrange the respective components in
relation to each other, and increase the usage efficiency of the
light. In addition, since this polarizing conversion unit 30A has a
simple structure such that the respective components 550, 540, 531,
and 532 are inserted into the unit frame 500 and are fixed by the
clip 560, the polarizing conversion unit 30A can be easily attached
and detached. This allows the respective components to be easily
exchanged.
94. Incidentally, just as described in the first embodiment,
projections may be provided in the centers of the upper and lower
inner surfaces of the recess 502b, and grooves corresponding to the
projections may be provided in the centers of upper and lower ends
of the lens array 550. Conversely, grooves may be provided in the
centers of upper and lower side surfaces of the recess 502b, and
projections corresponding to the grooves may be provided on the
lens array 550. This allows the lens array 550 to be arranged with
reference to the center projections.
95. In addition, while an example has been shown in this embodiment
in which the lens array 550, the light-shielding plate 540, and the
polarizing conversion element arrays 531 and 532 are inserted into
the unit frame 500 in this order, they may be inserted in reverse
order.
96. In addition, while a construction including the light-shielding
plate has been described in the first and second embodiments, a
construction that does not include the light-shielding plate may be
employed.
C. Construction of Projection Display Device
97. FIG. 13 is a schematic plan view showing a construction of a
projection display device incorporating the optical device of the
present invention, and shows a state where respective components
are mounted on the lower light guide 600D. This projection display
device 1000 consists of an illumination optical system composed of
a light source 10, a first lens array 20, an optical device
(polarizing conversion unit) 30 of the present invention, and a
superimposing lens 40. In addition, the projection display device
1000 consists of a reflecting mirror 42, a color light separation
optical system 50 including dichroic mirrors 52 and 56, and a
reflecting mirror 54. Furthermore, the projection display device
1000 consists of a light guide optical system including an
incident-side lens 62, a relay lens 66, and reflecting mirrors 64
and 68. In addition, the projection display device 1000 consists of
three sheets of field lenses 70, 72, and 74, three sheets of liquid
crystal light valves 80R, 80G, and 80B, a cross-dichroic prism 88,
and a projection lens 90.
98. Since the light source 10, the first lens array 20, the optical
device 30 and the superimposing lens 40 are the same as those of
the illumination optical system shown in FIG. 3, an explanation
thereof is omitted. The reflecting mirror 42 has the function of
reflecting light emitted from the superimposing lens 40 in the
direction of the color light separation optical system 50. The
color light separation optical system 50 has the function of
separating light emitted from the superimposing lens 40 into color
light of three colors, i.e., red, green, and blue. The first
dichroic mirror 52 transmits a red light component of the light
emitted from the superimposing lens 40, and reflects a blue light
component and a green light component. The red light transmitted by
the first dichroic mirror 52 is reflected from the reflecting
mirror 54, and passes through the field lens 70 to reach the red
light liquid crystal light valve 80R. This field lens 70 converts
respective partial luminous fluxes emitted from the superimposing
lens 40 into luminous fluxes parallel to the center axes (main
light beam) thereof. Similar descriptions apply to the field lenses
72 and 74 provided in front of other liquid crystal light
valves.
99. Of the blue light and the green light reflected from the first
dichroic mirror 52, the green light is reflected by the second
dichroic mirror 56, and passes through the field lens 72 to reach
the green light liquid crystal light valve 80G. On the other hand,
the blue light is transmitted through the second dichroic mirror
56, and passes through the light guide optical system 60, i.e., the
incident-side lens 62, the reflecting mirror 64, the relay lens 66,
and the reflecting mirror 68 and further, passes through the field
lens 74 to reach the blue light liquid crystal light valve 80B.
Incidentally, since the length of the optical path of the blue
light is longer than that of other color light, the light guide
optical system 60 is employed for the blue light in order to
prevent deterioration of the usage efficiency of the light due to
diffusion of light or the like. That is, the luminous flux incident
on the incident-side lens 62 is propagated to the field lens 74
without deterioration.
100. Three liquid crystal light valves 80R, 80G, and 80B function
as an optical modulation device for modulating the incident light
in accordance with given image information (image signal). This
allows each of the color light incident on the three liquid crystal
light valves 80R, 80G, and 80B to be modulated in accordance with
given image information to form images of each of the color light.
Incidentally, the illumination area 80 shown in FIG. 1 corresponds
to the liquid crystal light valves 80R, 80G, and 80B.
101. The modulated light of the three colors emitted from the three
liquid crystal light valves 80R, 80G, and 80B is incident on the
cross-dichroic prism 88. The cross-dichroic prism 88 functions as a
color light synthesizing section which forms a color image by
synthesizing modulated light of three colors. In the cross-dichroic
prism 88, a dielectric multilayer film for reflecting the red light
and a dielectric multilayer film for reflecting the blue light are
formed on the interfaces of four rectangular prisms in
substantially an X shape. The modulated light of three colors is
synthesized by these dielectric multilayer films, and synthesized
light for projecting a color image is formed. The synthesized light
formed in the cross-dichroic prism 88 is emitted to the direction
of the projection lens 90. The projection lens 90 has the functions
of projecting the synthesized light onto a projection screen, and
displays the color image on the projection screen.
102. Since the optical device (polarizing conversion unit) 30
described in the first embodiment is employed in the projection
display device of the present invention, the relative positional
accuracy of the optical elements (parts) included in this optical
device can be improved. This can increase the usage efficiency of
the light in the projection display device. In addition, the
components of this optical device are easily attachable and
detachable, even if a fault occurs in the projection display device
due to a fault of this optical device, faulty components included
in this optical device can be easily exchanged, so that the fault
of the projection display device can be easily solved. Even if the
optical device described in the second embodiment is employed,
similar effects can be obtained.
103. Incidentally, this invention is not limited to the above
embodiments and modes for carrying out the invention, and can be
carried out in various forms without departing from the spirit and
scope thereof. For example, the following modifications may be
made.
104. (1) The respective constructions of the lens array, the
light-shielding plate, and polarizing conversion element array
included in the optical device explained in the above first and
second embodiments show one example. That is, the respective
constructions of these lens array, light-shielding plate, and
polarizing conversion element array, for example, the number of
columns of the polarizing conversion element in the polarizing
conversion element array, the number of rows and columns of the
lens array, the presence of the light-shielding plate, and the
shape of the small lens constituting the lens array, should be
executed in various modes in response to the characteristics of the
respective components such as the light source and the like, and
the specifications of the projection display device.
105. (2) While the above projection display device employing the
light valves that utilizes transmissive liquid crystal panels as
the optical modulation device has been described, the light valves
may utilize reflective liquid crystal panels. In addition, the
projection display device may employ an optical modulation device
utilizing mirror elements.
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