JPH04366911A - Projection device - Google Patents

Abstract

PURPOSE:To make the brightness of an image, projected on a screen, high by effectively utilizing light which is emitted by a light source. CONSTITUTION:This projection device has a polarized light lighting device which converts the white light emitted by the light source 1 into P-polarized light Lp+Lp*, a liquid crystal light valve 10 which modulates the P-polarized light Lp+Lp* according to a color image signal and converts it into image light containing a P-polarized light component Lpo and an S-polarized component Lso, a projection lens 26 which projects the P-polarized light component Lpo of the image light on the screen, and a polarization beam splitter 25 for feedback which is interposed between the liquid crystal valve 10 and projection lens 26 and separates the P-polarized light component Lpo and S-polarized light component Lso and makes the P-polarized light component Lpo of the image light incident on the projection lens 26, and 1st, 2nd, and 3rd feedback reflecting mirrors 27, 28, and 29 which feed the S-polarized light component Lso of the image light back to the polarized light lighting device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device that projects an image onto a screen by illuminating a light modulator (hereinafter referred to as "modulator") such as a liquid crystal device.

0002

2. Description of the Related Art Conventionally, various systems have been proposed for this type of projection device.

FIG. 4 is a schematic diagram of a liquid crystal projection device disclosed in Japanese Patent Application Laid-Open No. 2-93580.

This liquid crystal projection device includes a light source 201, a mirror surface 202, a λ/4 optical phase plate 204,
Polarizing beam splitter 205 and plane reflector 217
a polarized illumination device consisting of a liquid crystal light valve 210;
, a polarizing plate 211 , and a projection lens 212 .

Parallel white light, which is undefined polarization light, emitted from the light source 201 passes through the λ/4 optical phase plate 204, and then enters the polarization beam splitter 205. The P-polarized light component is transmitted through the vapor-deposited film formed on the slopes where the prisms are bonded to each other, and the S-polarized light component is reflected at right angles to the lower side of the figure, thereby separating the P-polarized light component and the S-polarized light component. Ru.

The P-polarized light component transmitted through the working surface exits from the exit surface of the polarizing beam splitter 205,
The light enters the liquid crystal light valve 210, is modulated according to the color image signal, and is converted into image light containing a P-polarized light component and an S-polarized light component. The P-polarized component of the image light is transmitted through the polarizing plate 2.
After passing through the image light 11 , it is projected onto a screen (not shown) by a projection lens 212 , but the S-polarized component of the image light is absorbed by the polarizing plate 211 and converted into heat.

On the other hand, the S-polarized light component reflected by the working surface of the polarizing beam splitter 205 is reflected by the plane reflecting mirror 217.
The polarizing beam splitter 20 is reflected upward in the figure.
After being reflected perpendicularly to the left side in the figure from the action surface of 5, λ/
The light passes through the four optical phase plates 204 and returns to the light source 201 . The S polarized light component returned to the light source 201 is reflected on the mirror surface 202.
The light is reflected by the parallel white light emitted from the light source 201 and re-enters the polarizing beam splitter 205 along the aforementioned path. At this time, the S-polarized light component is reflected by the plane reflecting mirror 217 and outputted from the polarizing beam splitter 205, and then sent to the λ/4 optical phase plate 204.
By transmitting the light twice, the polarization direction is rotated by 90 degrees and converted into a P-polarized light component, so it is transmitted through the working surface of the polarizing beam splitter 205 and enters the liquid crystal light valve 210, and the color image is The light is modulated according to the signal and converted into image light including a P-polarized light component and an S-polarized light component. The P-polarized component of the image light passes through the polarizing plate 211 and is then projected onto the screen by the projection lens 212, while the S-polarized component of the image light passes through the polarizing plate 211.
is absorbed and converted into heat.

FIG. 5 is a schematic diagram of a liquid crystal type projection device disclosed in Japanese Patent Laid-Open No. 61-90584.

This liquid crystal projection device includes a light source 301 , a reflecting mirror 302 , an infrared cut filter 303 , a condenser lens 304 , a polarizing beam splitter 305 , a total reflection prism 321 , a λ/2 optical phase plate 322 and two wedge-shaped lenses 323 ，
A polarized illumination device consisting of 324 and a liquid crystal light valve 3
10, a polarizing plate 325, and a projection lens 326.

[0010] The white light, which is undefined polarized light, emitted from the light source 301 is converted into parallel white light LP+LS by the condenser lens 304 after the infrared light other than visible light is absorbed by the infrared cut filter 303. The parallel white light LP+LS enters the polarizing beam splitter 305, and the P-polarized light component LP is transmitted through the active surface 311a of the polarizing beam splitter 305 (deposited film formed on the slope where two right-angle prisms are bonded to each other). The S-polarized light component LS is reflected at right angles to the upper side in the drawing, thereby being separated into a P-polarized light component LP and an S-polarized light component LS.

The P-polarized light component LP is emitted from the exit surface of the polarization beam splitter 305. Further, the S-polarized light component LS enters the total reflection prism 321, is reflected at right angles to the right side in the figure on the slope of the total reflection prism 321, and then exits from the output surface of the total reflection prism 321 in parallel with the P-polarized light component LP. do. At this time, the S-polarized light component LS is transmitted through the λ/2 optical phase plate 322 provided opposite to the output surface of the total reflection prism 321, so that the polarization direction is rotated by 90 degrees and the P-polarized light component Converted to LP*. Polarizing beam splitter 30
Wedge-shaped lenses 323 and 324 for changing the optical path are respectively disposed on the exit surface sides of the 5 and λ/2 optical phase plates 322, and the P polarized light components LP and λ emitted from the polarizing beam splitter 305 are The converted P-polarized light component LP emitted from the /2 optical phase plate 322
* is the point P0 on the incident surface of the liquid crystal light valve 310
The optical paths are changed by the wedge lenses 323 and 324 so that they intersect at the point P0, and are combined at the point P0. As a result, parallel white light LP+LS becomes P-polarized light LP+LP*
is converted to

[0012] The P-polarized light LP+LP* is modulated by the liquid crystal light valve 310 according to a color image signal, and converted into image light containing a P-polarized light component and an S-polarized light component. After the P-polarized component of the image light passes through the polarizing plate 325,
The image light is projected onto a screen (not shown) by the projection lens 326, and the S-polarized component of the image light is absorbed by the polarizing plate 325 and converted into heat.

[0013]

[Problems to be Solved by the Invention] However, in the liquid crystal type projection device shown in FIG.
Since both the P-polarized light component and the S-polarized light component of the parallel white light emitted from the screen are incident on the liquid crystal light valve 210, the screen The brightness of the color image enlarged and projected can be doubled, but
Generally, color images have many intermediate tones, so 50 to 70% of the parallel white light emitted from the light source 201 is transferred to the polarizing plate 211.
There is a problem that the parallel white light cannot be used effectively.

In the liquid crystal projection device shown in FIG. 5, the P-polarized light component LP emitted from the polarizing beam splitter 305 and the P-polarized light component LP* emitted from the λ/2 optical phase plate 322 are arranged at an angle θ shown in the figure. By intersecting at the point P0, the parallel white light L
A liquid crystal light valve 310 that converts P+LS into P-polarized light LP +LP* has large characteristic deterioration depending on the incident angle.
When using each wedge type lens 323, 32
4 to the liquid crystal light valve 310 and it is necessary to make the angle θ small (
For example, in order to make the angle θ within ±10°, each of the distances needs to be 30 to 60 cm), there is a problem that the entire device cannot be made smaller and lighter. Total reflection prism 32 composed of prisms
1 and the respective wedge-shaped lenses 323 and 324, there is a problem that the size becomes larger than that shown in FIG. 50-70% of light
There is a problem in that the white light is absorbed by the polarizing plate 325 and the white light cannot be used effectively.

An object of the present invention is to provide a projection device that can increase the brightness of an image projected onto a screen by effectively utilizing the light emitted from a light source.

[0016]

[Means for Solving the Problems] A projection device of the present invention includes a polarized illumination device that converts undefined polarized light emitted from a light source into linearly polarized light, and a polarized illumination device that converts the linearly polarized light emitted from the polarized illumination device into an image signal. A projection device comprising: a liquid crystal device that modulates the image light according to the P-polarized light component and converts it into image light containing a P-polarized light component and an S-polarized light component; and a projection lens that projects the P-polarized light component of the image light emitted from the liquid crystal device onto a screen. , a polarizing beam splitter interposed between the liquid crystal device and the projection lens, which separates the P-polarized light component and the S-polarized light component of the image light, and causes the P-polarized light component of the image light to enter the projection lens. and a reflecting means for returning the S-polarized component of the image light separated by the polarizing beam splitter to the polarizing illumination device.

[0017] Here, the reflecting means may reflect S of the image light.
It has a λ/2 optical phase plate that rotates the polarization direction of a polarized light component by 90 degrees and converts it into a P-polarized light component, and a polarizing plate into which the P-polarized light component converted by the λ/2 optical phase plate is incident. You can.

[0018] Alternatively, an illumination system, a modulator that partially modulates the plane of polarization of light from the illumination system to form light representing an image, and the light representing the image from the modulator are orthogonal to each other. A projection system comprising: a polarization separation means that reflects a first component of polarization components and transmits a second component; and a projection system that receives one of the first component and the second component from the polarization separation means and projects an image. In the apparatus, the device receives at least a portion of the other light of the first component and the second component from the polarization separation means and directs the other light to the modulator via the illumination system. A return means will be provided to allow the return.

[0019] Here, the illumination system may include a light source and a conversion system that converts the light from the light source into polarized light, and the feedback means converts the other light into the conversion system. Alternatively, the conversion system may include a polarization splitter that splits the light from the light source into two lights whose polarization directions are orthogonal to each other, and a polarization splitter that splits the light from the light source into two lights whose polarization directions are orthogonal to each other. The polarizing element may include a polarizing element that modulates the plane of polarization of the one light so as to match the polarization direction of the light, and the polarizing element may include:
A 1/2 wavelength plate may be provided, and the polarizing element may include:
It may include a quarter wavelength plate and a reflecting mirror, or the
A /4 wave plate may be provided between the polarization splitter and the light source.

[0020] Also, the illumination system supplies red light, blue light, and green light, and the modulator includes a first liquid crystal panel that modulates the polarization plane of the red light. , a second liquid crystal panel that modulates the polarization plane of the blue light, and a third liquid crystal panel that modulates the polarization plane of the green light, and the polarization separation means and the projection system Color images may also be projected.

[0021]

[Operation] In the projection device of the present invention, the undefined polarized light emitted from the light source is converted into linearly polarized light by the polarization illumination device, and then enters the liquid crystal device, where it is modulated according to the image signal. It is converted into image light containing a polarized light component and an S-polarized light component. The image light is separated into a P-polarized component and an S-polarized component by a polarizing beam splitter, and the P-polarized component of the image light is projected onto a screen by a projection lens, while the S-polarized component of the image light is separated by a reflecting means. The light is returned to the polarized illumination device and used again to illuminate the liquid crystal device.

[0022] Also, in a projection device that does not use the polarized illumination device, the first component of the mutually orthogonal polarized components of the light representing the image from the modulator is provided between the modulator and the projection system. between the polarization separation means that reflects the light and transmits the second component, and the illumination system, directing at least a portion of the other light of the first component and the second component from the polarization separation means to the modulator via the illumination system. By providing a return means for receiving the other light and returning it to the illumination system,
Light that is not used as image light can be made incident on the modulator again.

[0023]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of a projection apparatus according to the present invention.

This projection device transforms the white light, which is undefined polarized light, emitted from the light source 1 into P, which is linearly polarized light.
Light source 1, reflection mirror 2, infrared cut filter 3, condenser lens 4, polarization beam splitter 5, total reflection prism 21, λ/2 optical phase plate 22, and two wedge-shaped lenses 23, 24, which convert into polarized light LP+LP* A polarized illumination device consisting of a polarized illumination device, and P emitted from the polarized illumination device
A liquid crystal light valve 1, which is a liquid crystal device, modulates polarized light LP+LP* according to a color image signal and converts it into image light including a P polarized light component LP0 and an S polarized light component LS0.
0 and a projection lens 26 that projects the P-polarized component LP0 of the image light emitted from the liquid crystal light valve 10 onto a screen (not shown). .

However, the P-polarized component L of the image light interposed between the liquid crystal light valve 10 and the projection lens 26
a feedback polarization beam splitter 25 that separates P0 and S polarization component LS0 and makes the P polarization component LP0 of the image light enter the projection lens 26; and feedback polarization beam splitter 2.
As shown in FIG. This is different from the one shown in 5.

Here, the first feedback reflection mirror 27 is
It is provided to reflect the S-polarized component LS0 of the image light separated by the feedback polarizing beam splitter 25 at right angles to the left side in the figure, and the second feedback reflection mirror 2
Reference numeral 8 is provided to reflect the S-polarized component LS0 of the image light reflected by the first feedback reflection mirror 27 at right angles to the lower side in the figure. , is provided so that the S-polarized component LS0 of the image light reflected by the second feedback reflection mirror 28 is reflected to the right side in the figure at a predetermined angle and made to enter the slope of the total reflection prism 21. Note that the predetermined angle is such that the optical axis of the S-polarized light component LS0 of the image light reflected by the third feedback reflection mirror 29 after entering the total reflection prism 21 is parallel to the optical axis of the image light. It is set to be. In addition,
The angle of incidence when the S-polarized component LS0 of the image light is incident on the slope of the total reflection prism 21 is about 45°, and the reflectance on the slope can be about 1%. The total reflection prism 21 reflects most of the S polarized light component LS0 of
It can be made to enter inside.

Next, the operation of this projection device will be explained.

The white light emitted from the light source 1 is converted into parallel white light LP+LS by the condenser lens 4 after the infrared light other than visible light is absorbed by the infrared cut filter 3. The parallel white light LP+LS enters the polarizing beam splitter 5, and the working surface of the polarizing beam splitter 5 (
The P-polarized light component LP is transmitted through the vapor-deposited film formed on the slope where the two right-angle prisms are bonded to each other (11a), and the S-polarized light component LS is reflected at right angles to the upper side of the drawing, so that the P-polarized light components LP and S are It is separated into a polarization component LS.

The P-polarized light component LP is emitted from the exit surface of the polarizing beam splitter 5. Further, the S polarized light component LS enters the total reflection prism 21, is reflected at right angles to the right side in the figure on the slope of the total reflection prism 21, and then is reflected at right angles to the right side in the figure.
The light is emitted from the exit surface of the total reflection prism 21 in parallel to the polarized light component LP. At this time, the S-polarized light component LS
By passing through the /2 optical phase plate 22, the polarization direction is rotated by 90 degrees and converted into a P-polarized light component LP*.

Wedge-shaped lenses 23 and 24 for changing the optical path are disposed on the exit surfaces of the polarizing beam splitter 5 and the λ/2 optical phase plate 22, respectively, so that the beams emitted from the polarizing beam splitter 5 P polarized light component LP and the converted P emitted from the λ/2 optical phase plate 22
The polarized light component LP* is transmitted through each wedge-shaped lens 23, 24 so as to intersect at a point P0 on the incident surface of the liquid crystal light valve 10.
The optical paths are respectively changed at the point P0 and combined at the point P0. As a result, parallel white light LP+LS becomes P-polarized light LP+L
Converted to P*.

The P-polarized light LP+LP* is modulated by the liquid crystal light valve 10 according to the color image signal, and converted into image light containing a P-polarized light component LP0 and an S-polarized light component LS0. After the P-polarized component LP0 of the image light passes through the active surface of the feedback polarizing beam splitter 25 (the vapor deposited film formed on the slope where the two right-angle prisms are bonded to each other),
The projection lens 26 projects the image onto the screen.

On the other hand, the S-polarized component LS0 of the image light is:
After being reflected perpendicularly upward in the drawing from the action surface of the feedback polarizing beam splitter 25, it is returned to the total reflection prism 21 by the first, second, and third feedback reflection mirrors 27, 28, and 29. Thereafter, the S-polarized component LS0 of the image light is emitted from the output surface of the total reflection prism 21, transmitted through the λ/2 optical phase plate 22, the polarization direction is rotated by 90 degrees, and the optical path is passed through the wedge-shaped lens 23. is changed and combined with the P-polarized light component LP of the parallel white light LP+LS at the point P0, and then enters the liquid crystal light valve 10 again.

Therefore, in this projection device, the polarizing plate 325 is different from the conventional one shown in FIG.
The S-polarized component L of the image light absorbed by and converted into heat
Since S0 can be made to enter the liquid crystal light valve 10 again, the white light emitted from the light source 1 can be effectively used, so that the color image enlarged and projected on the screen can be increased in brightness.

FIG. 2 is a schematic diagram showing a second embodiment of the projection apparatus of the present invention.

This projection device includes a polarized illumination device 30 and white P-polarized light PR+PG+PB emitted from the polarized illumination device 30 into red, green, and blue P-polarized light PR,
A color separation means for separating into PG and PB, and a color separation means for modulating the P-polarized light PR, PG, PB of each color separated by the color separation means according to the red component, green component, and blue component of the color image signal, Each color image light R including a polarized light component and an S-polarized light component
*, G*, B*, and each color image light R*, emitted from each liquid crystal device.
A color synthesis means for synthesizing G* and B* and converting it into image light R*+G**+B*, and a P polarization component and an S polarization component of the image light R*+G**+B* converted by the color synthesis means. a feedback polarizing beam splitter 95 that separates the image light R*+G*+B* and makes the P-polarized component of the image light R*+G*+B* enter the projection lens 90; S of image light R*+G*+B* separated by a projection lens 90 that projects the P-polarized component onto a screen (not shown) and a polarizing beam splitter 95 for feedback
It has a reflecting means for returning the polarized light component to the polarized illumination device 30.

Each component of the above-mentioned projection device will be explained in detail below.

(a) Polarized illumination device 30 As shown in FIG. 3, the polarized illumination device 30 includes a parabolic reflecting mirror 32 and an undefined polarized light disposed near the focal point of the parabolic reflecting mirror 32. a light source section having a light source 31 made of a metal halide lamp or the like that emits white light LP+LS; a λ/4 optical phase plate 34 provided perpendicularly to the optical axis of the white light LP+LS emitted from the light source section; An infrared cut filter 33 is provided between the light source section and the λ/4 optical phase plate 34 so as to face the λ/4 optical phase plate 34, and the λ/4 optical phase plate 34 faces the entrance surface 351. A polarizing beam splitter 35 having a right triangular cross-sectional shape in which one side of the incident surface 351 and one side of the exit surface 352 touch at an angle of 90 degrees, and a polarizing beam splitter 35 provided on the exit surface 352 side of the polarizing beam splitter 35. A condensing lens 36 is provided.

The polarizing beam splitter 35 has one side in contact with one side of the incident surface 351 at an angle of 45°, and the other side in contact with an inclined surface.
Transmits the polarized light component LP and transmits the S polarized light component LS.
a working surface 354 (deposited film formed on the slope where two right-angle prisms are bonded to each other) that reflects the light, and a reflective surface 35 formed by providing a reflective film (not shown) on the slope.
3.

The white light LP+LS (shown by a solid line in FIG. 3) emitted from the light source 31 toward the parabolic reflector 32 is reflected by the parabolic reflector 32 and converted into parallel light, and then is cut into infrared rays. The light enters the filter 33, and the infrared light other than visible light is absorbed by the infrared cut filter 33. After that, the white light LP+LS passes through the λ/4 optical phase plate 34 and then enters the polarizing beam splitter 35, where the P polarized light component LP
is transmitted, and the S-polarized light component LS is reflected at right angles to the right side in the drawing, thereby being separated into a P-polarized light component LP and an S-polarized light component LS.

The P-polarized light component LP transmitted through the working surface 354 is reflected at right angles to the left side in the figure by the reflective surface 353 formed on the slope of the polarizing beam splitter 35, and then exits from the output surface 352, and then passes through the condenser lens. The light is focused at 36.

On the other hand, the S reflected by the action surface 354
The polarization component LS (indicated by a broken line in the figure) is
53 and is reflected at right angles to the upper side in the drawing, exits from the incident surface 351 of the polarizing beam splitter 35, passes through the λ/4 optical phase plate 34 and the infrared cut filter 33, and enters the parabolic reflecting mirror 32. The S polarization component LS
is reflected toward the light source 31 by the parabolic reflector 32, and
After passing through the vicinity of 1, the light is reflected again by the parabolic reflector 32 and exits from the light source section as parallel light. The S-polarized light component LS emitted from the light source passes through the infrared cut filter 33 and the λ/4 optical phase plate 34 and enters the polarization beam splitter 35 again. At this time, the S-polarized light component LS is reflected by the reflective surface 353 and then transmitted twice through the λ/4 optical phase plate 34, thereby rotating the polarization direction by 90 degrees and converting it into a P-polarized light component LP*. Therefore, after passing through the working surface 354 , the light is reflected at right angles to the left side in the drawing by the reflecting surface 353 , exits from the output surface 352 , and is condensed by the condensing lens 36 .

Therefore, the light emitted from the polarized illumination device 30 becomes white P-polarized light PR+PG+PB in which the polarization direction of the white light LP+LS, which is undefined polarized light, is aligned.

(b) Color separation means The color separation means separates the yellow P-polarized light PR+ out of the white P-polarized light PR+PG+PB emitted from the polarized illumination device 30.
A first decomposing dichroic mirror 8 that transmits the PG and reflects the blue P-polarized light PB at right angles to the upper side in FIG.
1, red P-polarized light PR out of yellow P-polarized light PR+PG
a second decomposition dichroic mirror 82 that transmits the green P-polarized light PG and reflects the green P-polarized light PG at right angles to the upper side of the drawing;
It consists of a decomposition reflecting mirror 83 that reflects the blue P-polarized light PB at right angles to the left side in the figure.

(c) Each liquid crystal device Each liquid crystal device has a second disassembling dichroic mirror 5 whose output surface is supported by a transparent support plate 93R.
a red liquid crystal panel 84R that modulates the red P-polarized light PR transmitted by the second P-polarized light PR according to the red component of the color image signal;
The green color P reflected by the decomposition dichroic mirror 52
A green liquid crystal panel 84G that modulates the polarized light PG according to the green component of the color image signal, and a decomposition reflecting mirror 83 whose output surface is supported by a transparent support plate 93B.
a blue liquid crystal panel 84B that modulates the blue P-polarized light PB reflected by the blue color image signal according to the blue component of the color image signal;
It consists of

(d) Color synthesis means The color synthesis means reflects the green image light G* emitted from the green liquid crystal panel 84G at right angles to the left side in the drawing, and reflects the green image light G* emitted from the blue liquid crystal panel 84B into blue image light B* emitted from the blue liquid crystal panel 84B. By transmitting green image light G* and blue image light B
* The first to synthesize cyan image light G*+B*
a synthesis dichroic mirror 85, a synthesis reflection mirror 86 that reflects the red image light R* emitted from the red liquid crystal panel 84R at a right angle upward in the figure, and a synthesis reflection mirror 86 that reflects the red image light R* reflected by the synthesis reflection mirror 86. By reflecting the image light at a right angle to the left side in the figure and transmitting the cyan image light G*+B*, the red image light R* and the cyan image light G* +
A second synthesis dichroic mirror 87 synthesizes image light R*+G*+B* with image light R*+G*+B*.

(E) Feedback polarizing beam splitter 95 The feedback polarizing beam splitter 95 is interposed between the second combining dichroic mirror 87 and the projection lens 90, which is between the liquid crystal device and the projection lens. The image light R*+G*+B* is separated into a P-polarized component LP0 and an S-polarized component LS0, and the P-polarized component LP0 of the image light R*+G*+B* is made to enter the projection lens 90.

(f) Reflection means The reflection means reflects the S polarization component LS0 of the image light R*+G*+B* separated by the feedback polarization beam splitter 95.
The first, second and third
It consists of feedback reflection mirrors 97, 98, 99, and a λ/2 optical phase plate 72 and a polarizing plate 73 interposed between the second feedback reflection mirror 98 and the third feedback reflection mirror 99. .

Here, the first feedback mirror 97 is
Image light R separated by feedback polarizing beam splitter 95
The second feedback reflection mirror 98 is provided to reflect the S-polarized component LS0 of *+G*+B* at right angles to the right side in the figure, and the second feedback reflection mirror 98 reflects the image light R reflected by the first feedback reflection mirror 97. It is provided so as to reflect the S-polarized light component LS0 of *+G*+B* at right angles to the upper side in the figure. Also,
The λ/2 optical phase plate 72 and the polarizing plate 73 receive the image light R*+G*+B* reflected by the second feedback reflection mirror 98.
The polarization direction of the S-polarized light component LS0 is rotated by 90 degrees, and the polarization direction is rotated by 90 degrees, and
54 (see FIG. 3) to selectively transmit the P-polarized light component LP0*. Further, the third feedback reflection mirror 99 is configured to receive the P-polarized light component LP0 selectively transmitted by the λ/2 optical phase plate 72 and the polarizing plate 73.
* is reflected to the left side in the figure at a predetermined angle, and the reflecting surface 353 (
(see FIG. 3). In addition,
The predetermined angle is such that the optical axis within the polarizing beam splitter 35 (see FIG. 3) of the P-polarized light component LP0* that enters the center of the reflective surface 353 after being reflected by the third feedback reflection mirror 99 is determined by the predetermined angle. , are set to be parallel to the optical axis of the image light R*+G*+B*.

Next, the operation of this projection device will be explained.

The white light, which is undefined polarized light, emitted from the light source 31 shown in FIG.
(linearly polarized light) and is emitted from the polarized illumination device 30.

As shown in FIG. 2, white P-polarized light PR+P
G+PB is the first disassembling dichroic mirror 81
The yellow P-polarized light PR + PG is separated into the blue P-polarized light PR + PG and the yellow P-polarized light PR + PG is separated into the red P-polarized light PR and the green P-polarized light PG by the second splitting dichroic mirror 82. By doing so, it is decomposed into red, green, and blue P-polarized light PR, PG, and PB.

The red P-polarized light PR is modulated by rotating the polarization direction in accordance with the red component of the color image signal in the red liquid crystal panel 84R, and is divided into the P-polarized light PR and the S-polarized light PR.
The red image light R* is converted into red image light R* containing a polarized component, and is transmitted through the transparent support plate 93R and emitted.

Similarly, the green P-polarized light PG is modulated by the green liquid crystal panel 84G according to the green component of the color image signal, and converted into green image light G* containing the P-polarized component and the S-polarized component. The light passes through the transparent support plate 93G and is emitted. Further, the blue P-polarized light PB is reflected by the decomposition reflecting mirror 83 and then reflected by the blue liquid crystal panel 84.
B is modulated according to the blue component of the color image signal, converted into blue image light B* containing a P polarization component and an S polarization component, and transmitted through the transparent support plate 93B and emitted.

The red image light R* is transmitted to the combining reflection mirror 8.
After being reflected at right angles to the upper side in the drawing at 6, the light enters a second synthesis dichroic mirror 87. Further, the green image light G* and the blue image light B* are combined by the first combining dichroic mirror 85, and the cyan image light G*+B
After being converted into *, the light enters the second synthesis dichroic mirror 87 .

The second synthesis dichroic mirror 87 reflects the red image light R* at right angles to the left side in the drawing, and transmits the cyan image light G*+B*, thereby combining the red image light R* and the cyan image light. G*+B* are synthesized, and image light R*+G*+B* corresponding to the color image signal is emitted from the second synthesis dichroic mirror 87.

The image light R*+G*+B* is separated into a P-polarized component LP0 and an S-polarized component LS0 by the feedback polarizing beam splitter 95, and the P-polarized component LP0 of the image light R*+G*+B* is sent to the projection lens. The color image is projected onto a screen (not shown) by 90, and the color image is enlarged and displayed on the screen.

On the other hand, the S-polarized component LS0 of the image light R*+G*+B* is transmitted to the first and second feedback reflection mirrors 97.
, 98 to the λ/2 optical phase plate 72.
The polarization direction becomes 90 by passing through the 2 optical phase plate 72.
After being rotated by °, the polarizing beam splitter 3 of the polarizing illumination device 30 is selectively transmitted through the polarizing plate 73.
P polarized light component L with respect to the action surface 354 of 5 (see FIG. 3)
P0* and returns to the polarized illumination device 30. Thereafter, the image light R* converted into the P polarized light component LP0*
The S polarization component LS0 of +G*+B* is the polarization illumination device 3.
0, each of the liquid crystal panels 84R, 84G, 84
Used for B lighting.

Therefore, in this projection device, the polarizing plate 325 is
Image light R*+G*+B* absorbed by and converted into heat
The S polarized light component LS0 of each of the liquid crystal panels 84R, 84
G, 84B can be input again, so the light source 3
Since the white light LP+LS emitted from the screen can be effectively used, the color image enlarged and projected onto the screen can be increased in brightness.

Furthermore, this projection device does not require the wedge-shaped lenses 23 and 24 shown in FIG.
Moreover, as shown in FIG. 3, each liquid crystal panel 84R, 84G, 84B can be illuminated by the polarized illumination device 30, which is smaller and lighter than the polarized illumination device shown in FIG. 1, so the entire device can be made smaller and lighter. I can figure it out.

Note that in this projection device, λ
The /2 optical phase plate 72 and the polarizing plate 73 were interposed between the second feedback reflection mirror 98 and the third feedback reflection mirror 99, but the feedback polarization beam splitter 95 and the first
or between the first feedback mirror 97 and the second feedback mirror 98.

In the above explanation, the linearly polarized light irradiated to the liquid crystal device was assumed to be P polarized light, but for example, as shown in FIG.
In the projection device shown in FIG. 1, the λ/2 optical phase plate 22 may be disposed on the exit surface side of the polarizing beam splitter 5 to irradiate the S-polarized light onto the liquid crystal light valve 10.

[0063]Although the projection device was designed to enlarge and project a color image onto a screen, it is now possible to enlarge and project a black and white image onto a screen by using a liquid crystal device that modulates white light according to the black and white of the image signal. You can do it like this.

Furthermore, as a projection device,
It may be possible to reduce a color image or a monochrome image and project it onto a screen, or it may be possible to project only a blue image by using a light source section that emits blue light, for example.

The present invention is also applicable to a projection device that does not use a polarized illumination device.

That is, an illumination system, a modulator that partially modulates the plane of polarization of light from the illumination system to form light representing an image, and a light beam representing the image from the modulator that is orthogonal to each other. A projection system comprising: a polarization separation means that reflects a first component of polarization components and transmits a second component; and a projection system that receives one of the first component and the second component from the polarization separation means and projects an image. In the apparatus, the device receives at least a portion of the other light of the first component and the second component from the polarization separation means and directs the other light to the modulator via the illumination system. By providing a feedback means for making a return, the same effect as the projection device shown in FIG. 1 can be obtained.

[0067] Here, the illumination system may include a light source and a conversion system such as a polarizing plate that converts the light from the light source into polarized light, and the feedback means converts the other light into polarized light. A similar effect can be obtained even if the light is made incident on the conversion system.

[0068] The conversion system also includes a polarization splitter that splits the light from the light source into two lights whose polarization directions are orthogonal to each other, and a polarization splitter that splits the light from the light source into two lights whose polarization directions are orthogonal to each other; A similar effect can be obtained even if the light beam includes a polarizing element that modulates the plane of polarization of one of the lights so as to match the direction. At this time, the polarizing element may be provided with a 1/2 wavelength plate, or may be provided with a 1/4 wavelength plate and a reflecting mirror, and the 1/4 wavelength plate may be It may be provided between the polarization splitter and the light source.

Furthermore, the illumination system supplies red light, blue light, and green light, and the modulator includes:
a first liquid crystal panel that modulates the polarization plane of the red light;
a second liquid crystal panel that modulates the polarization plane of the blue light;
Similar effects can be obtained even if the device includes a third liquid crystal panel that modulates the polarization plane of the green light and projects a color image via the polarization separation means and the projection system.

[0070]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

The projection apparatus according to claims 1 and 2 separates the P-polarized light component and the S-polarized light component of the image light, which are interposed between the liquid crystal device and the projection lens,
By including a polarizing beam splitter that makes the P-polarized component of the image light enter the projection lens, and a reflecting means that returns the S-polarized component of the image light separated by the polarized beam splitter to the polarizing illumination device, In this projection device, the S-polarized component of the image light, which was converted into heat as unnecessary light, can be used again to illuminate the liquid crystal device, so the undefined polarized light emitted from the light source can be effectively used. Therefore, there is an effect that the brightness of the image projected on the screen can be increased.

Further, the projection device according to claims 3 to 10 is arranged so that at least a part of the other light of the first component and the second component from the polarization separation means is directed to the modulator via the illumination system. By providing a feedback means that receives the light and returns it to the illumination system, the light emitted from the illumination system can be effectively used, which has the effect of increasing the brightness of the image projected on the screen.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a projection device of the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the projection device of the present invention.

FIG. 3 is a schematic configuration diagram of the polarized illumination device shown in FIG. 2.

FIG. 4 is a schematic configuration diagram of a liquid crystal projection device described in Japanese Patent Application Laid-Open No. 2-93580.

FIG. 5 is a schematic configuration diagram of a liquid crystal projection device described in Japanese Patent Application Laid-Open No. 61-90584.

[Explanation of symbols]

1, 31 light source 2, reflective mirror 3, 33
Infrared cut filter 4
Condenser lens 5, 35
Polarizing beam splitter 10
Liquid crystal light valve 11a Working surface 21 Total reflection prisms 22, 7
2 λ/2 optical phase plate 23, 24
Wedge-shaped lens 25, 95 Return polarizing beam splitter 26, 90 Projection lens 27, 97 First return reflection mirror 28,
98 Second feedback reflection mirror 29, 99
Third return reflection mirror 30
Polarized illumination device 32
Parabolic reflecting mirror 34 λ/4 optical phase plate 351 Incident surface 352 Output surface 353 Reflecting surface 354 Working surface 36 Condensing lens 73
Polarizing plate 81 First dichroic mirror for decomposition 82 Second dichroic mirror for decomposition 83 Reflective mirror for decomposition 84R Red liquid crystal panel 84G Green liquid crystal panel 84B Blue liquid crystal panel 85
First dichroic mirror for synthesis 86 Reflection mirror for synthesis 87 Second dichroic mirror for synthesis 93R, 93G, 93B Transparent support plate LP+LS
White light LP, LP*, LP0, LP0* P polarized light component LS, LS0
S-polarized light component PR Red P-polarized light PG Green P-polarized light PB
Blue P polarized light PR+PG
Yellow P-polarized light PR+PG+PB White P-polarized light

Claims (10)

[Claims] 1. A polarized illumination device that converts undefined polarized light emitted from a light source into linearly polarized light, and a polarized illumination device that modulates the linearly polarized light emitted from the polarized illumination device according to an image signal,
a liquid crystal device that converts the image light into image light including a polarized light component and an S-polarized light component;
In a projection device having a projection lens that projects a polarized component onto a screen, the image light is separated into a P polarized component and an S polarized component, which are interposed between the liquid crystal device and the projection lens. a polarizing beam splitter that makes the P-polarized light component of the P-polarized light component enter the projection lens;
A projection device comprising: a reflecting means for returning the S-polarized component of the image light separated by the polarizing beam splitter to the polarizing illumination device. 2. The reflecting means rotates the polarization direction of the S-polarized component of the image light by 90 degrees and converts it into a P-polarized component.
2. The projection device according to claim 1, further comprising a 2-optical phase plate and a polarizing plate into which the P-polarized light component converted by the λ/2 optical phase plate is incident. 3. An illumination system; a modulator that partially modulates the plane of polarization of light from the illumination system to form light indicative of an image;
polarization separation means for reflecting a first component and transmitting a second component of mutually orthogonal polarization components of the light representing the image from the modulator; a projection system that receives one of the lights and projects an image thereon, at least a part of the other light of the first component and the second component from the polarization separation means is transmitted to the modulator via the illumination system; A projection apparatus comprising a feedback means for receiving the other light and returning it to the illumination system. 4. The projection apparatus according to claim 3, wherein the illumination system includes a light source and a conversion system that converts light from the light source into polarized light. 5. The projection apparatus according to claim 4, wherein the feedback means causes the other light to enter the conversion system. 6. The conversion system includes a polarization splitter that splits the light from the light source into two lights whose polarization directions are orthogonal to each other; 5. The projection device according to claim 4, further comprising a polarizing element that modulates the plane of polarization of the one light so as to match the direction. 7. The projection device according to claim 6, wherein the polarizing element includes a 1/2 wavelength plate. 8. The projection device according to claim 6, wherein the polarizing element includes a quarter wavelength plate and a reflecting mirror. 9. The projection device according to claim 8, wherein the quarter-wave plate is provided between the polarization splitter and the light source. 10. The illumination system supplies red light, blue light, and green light, and the modulator comprises a first liquid crystal panel that modulates the polarization plane of the red light. , a second liquid crystal panel that modulates the polarization plane of the blue light, and a third liquid crystal panel that modulates the polarization plane of the green light, and the polarization separation means and the projection system 4. The projection device according to claim 3, wherein the projection device projects a color image.