A polarizing conversion device in accordance with the invention includes a first optical element for condensing an incident beam and forming a plurality of intermediate beams spatially separated from one another, and a second optical element for spatially separating each intermediate beam into two polarized beams and aligning the polarization directions of the polarized beams, thereby obtaining the same type of polarized beams. In the second optical element, a shading plate is placed to prevent light from directly entering a section corresponding to a reflecting plane of a polarizing separation unit array. Since the ability of separating the intermediate beam into two polarized beams is thereby enhanced, it is possible to perform conversion into the same type of polarized beams polarized in the same direction, with high efficiency.
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27. A polarizing conversion device, comprising:
means for separating P and s polarized beams, including a separation plane, a reflecting plane, a light incident side and a light emergent side, by transmitting one of the P and s polarized beams through the separation plane toward the light emergent side, reflecting the other of the P and s polarized beams with the separation plane, and reflecting the other of the P and s polarized beams reflected with the separation plane toward the light emergent side with the reflecting plane;
means for aligning a polarization direction of one of the P and s polarized beams separated by the means for separating with a polarization direction of the other of the P and s polarized beams; and
means for preventing light from directly entering the reflecting plane.
1. A polarizing conversion device, comprising:
a polarizing separation element having a light incident side, a light emergent side, a polarizing separation plane that separate P and s polarized beams by transmitting one of the P and s polarized beams therethrough toward the light emergent side of the polarizing separation element and reflecting the other of the P and s polarized beams, and a reflecting plane disposed substantially parallel with said polarizing separation plane that reflects the other of the P and s polarized beams reflected by said polarizing separation plane toward the light emergent side of the polarizing separation element;
a selective phase plate disposed at the light emergent side of said polarizing separation element that aligns a polarization direction of one of the P and s polarized beams separated by said polarizing separation element with a polarization direction of the other of the P and s polarized beams, and
a device for preventing light from directly entering said reflecting plane disposed at the light incident side of said polarizing separation element.
22. A method of converting randomly polarized beams into substantially one type of polarized beams, comprising the steps of:
separating P and s polarized beams with a polarizing separation element by transmitting one of the P and s polarized beams through a separation plane of the polarizing separation element toward a light emergent side of the polarizing separation element, reflecting the other of the P and s polarized beams with the separation plane, and reflecting the other of the P and s polarized beams reflected with the separation plane toward the light emergent side of the polarizing separation element with a reflecting plane that is disposed substantially parallel with the polarizing separation plane;
aligning a polarization direction of one of the P and s polarized beams separated by the polarizing separation element with a polarization direction of the other of the P and s polarized beams with a selective phase plate disposed at the light emergent side of the polarizing separation element; and
preventing light from directly entering the reflecting plane with at least one of a shading device and an optical attenuating device.
8. A polarizing illumination device, comprising:
a light source that emits a light beam;
a first optical element that separates the light beam emitted from said light source into a plurality of intermediate beams that converge at a converging position; and
a second optical element disposed at or near the converging position, the second optical element including:
a condenser lens array that includes a plurality of condenser lenses that respectively condense the intermediate beams;
a polarizing separation element that spatially separates each of the intermediate beams into an s polarized beam and a P polarized beam, the polarizing separation element including a light incident side, a light emergent side, a polarizing separation plane that separates P and s polarized beams by transmitting one of the P and s polarized beams therethrough toward the light emergent side of the polarizing separation element and reflecting the other of the P and s polarized beams, and a reflecting plane disposed substantially parallel with said polarizing separation plane that reflects the other of the P and s polarized beams reflected by said polarizing separation plane toward the light emergent side of the polarizing separation element;
a selective phase plate that aligns a polarization direction of one of the P and s polarized beams is separated by said polarizing separation element with a polarization direction of the other of the P and s polarized beams;
a superimposing lens that superimposes the polarized beams; and
a device for preventing each of the intermediate beams from directly entering said reflecting plane interposed between said first optical element and said polarizing separation element.
18. A display apparatus, comprising:
a light source that emits a light beam;
a first optical element that separates the light beam emitted from said light source into a plurality of intermediate beams that converge at a converging position;
a second optical element disposed at or near the converging position, the second optical element including:
a condenser lens array that includes a plurality of condenser lenses that respectively condense the intermediate beams;
a polarizing separation element that spatially separates each of the intermediate beams into an s polarized beam and a P polarized beam, the polarizing separation element including a light incident side, a light emergent side, a polarizing separation plane that separates P and s polarized beams by transmitting one of the P and s polarized beams therethrough toward the light emergent side of the polarizing separation element and reflecting the other of the P and s polarized beams, and a reflecting plane disposed substantially parallel with said polarizing separation plane that reflects the other of the P and s polarized beams reflected by said polarizing separation plane toward the light emergent side of the polarizing separation element;
a selective phase plate that aligns a polarization direction of one of the P and s polarized beams separated by said polarizing separation element with a polarization direction of the other of the P and s polarized beams,
a superimposing lens that superimposes the polarized beams; and
a device for preventing each of the intermediate beams from directly entering said reflecting plane interposed between said first optical element and said polarizing separation element; and
a modulating device for modulating a light beam emitted from said second optical element.
19. A projection display apparatus projector, comprising:
a light source that emits a light beam;
a first optical element that separates the light beam emitted from said light source into a plurality of intermediate beams that converge at a converging position
a second optical element disposed at or near the converging position, the second optical element including:
a condenser lens array that indicates a plurality of condenser lenses that respectively condense the intermediate beams;
a polarizing separation element that spatially separates each of the intermediate beams into an s polarized beam and a P polarized beam, the polarizing separation element including a light incident side, a light emergent side, a polarizing separation plane that separates P and s polarized beams by transmitting one of the P and s polarized beams therethrough toward the light emergent side of the polarizing separation element and reflecting the other of the P and s polarized beams, and a reflecting plane disposed substantially parallel with said polarizing separation plane that reflects the other of the P and s polarized beams reflected by said polarizing separation plane toward the light emergent side of the polarizing separation element;
a selective phase plate that aligns a polarization direction of one of the P and s polarized beams separated by said polarizing separation element with a polarization direction of the other of the P and s polarized beams;
a superimposing lens that superimposes the polarized beams; and
a device for preventing each of the intermediate beams from directly entering said reflecting plane interposed between said and first optical element and said polarizing separation element;
at least one modulating device for modulating a light beam emitted from said second optical element according to display information; and
a projection optical system for projecting the light beam modulated by said modulating device onto a projection plane.
2. The polarizing conversion device according to
3. The polarizing conversion device according to
4. The polarizing conversion device according to
5. The polarizing conversion device according to
6. The polarizing conversion device according to
7. The polarizing conversion device according to
9. The polarizing illumination device according to
10. The polarizing illumination device according to
11. The polarizing illumination device according to
12. The polarizing illumination device according to claim 9 47, wherein said shading device is a reflecting film and said reflecting film is formed on a light emergent surface of said condenser lens array.
13. The polarizing illumination device according to
14. The polarizing illumination device according to
15. The polarizing illumination device according to claim 9 47, wherein said optical attenuating device is a light diffusing surface formed on a light emergent surface of said condenser lens array.
16. The polarizing illumination device according to
17. The polarizing illumination device according to claim 8 46, wherein said device for preventing each of the intermediate beams from directly entering said reflecting plane is integrated with said condenser lens array.
20. The projection display apparatus projector according to
color light separation system for separating the light beam into a plurality of colored lights;
a plurality of said modulating devices for respectively modulating the colored lights; and
colored light synthesizing system for synthesizing the colored lights modulated by said plurality of modulating devices;
wherein a synthesized beam synthesized by said colored light synthesizing system is projected onto said projection plane through said projection optical system.
21. The projection display apparatus projector according to
23. The method according to
24. The method according to
25. The method according to
26. The method according to
0. 28. The display apparatus according to
0. 29. The display apparatus according to
0. 30. The display apparatus according to
0. 31. The display according to
0. 32. The display apparatus to
0. 33. The display apparatus according to
0. 34. The display apparatus according to
0. 35. The display apparatus according to
0. 36. The display apparatus according to
0. 37. The projector according to
0. 38. The projector according to
0. 39. The projector according to
0. 40. The projector according to
0. 41. The projector according to
0. 42. The projector according to
0. 43. The projector according to
0. 44. The projector according to
0. 45. The projector according to
0. 46. The polarizing illumination device according to
a condenser lens array that includes a plurality of condenser lenses that respectively condense the intermediate beams.
0. 47. The polarizing illumination device according to
0. 48. The polarizing illumination device according to
0. 49. The display apparatus according to
a condenser lens array that includes a plurality of condenser lenses that respectively condense the intermediate beams.
0. 50. The display apparatus according to
0. 51. The display apparatus according to
0. 52. The projector according to
a condenser lens array that includes a plurality of condenser lenses that respectively condense the intermediate beams.
0. 53. The projector according to
0. 54. The projector according to
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1. Field of the Invention
The present invention relates to a polarizing conversion device and a polarizing illumination device for generating, from incident light beams as randomly polarized beams, illuminating beams that have a more uniform light intensity distribution in an illumination region than that of the incident beams and are polarized in almost the same direction. Furthermore, the present invention relates to a display apparatus and a projection display apparatusprojection display apparatus projector in which the polarization illumination device 1 described in the first embodiment is incorporated. In this embodiment, a transmission-type liquid crystal device is used as a modulating device for modulating light beams emitted from the polarizing illumination device according to display information.
The polarizing illumination device 1 of this embodiment has a light source section 10 for emitting randomly polarized beams in one direction, and the randomly polarized beams emitted from the light source section 10 are converted into substantially the same type of polarized beams by a polarized light generating device 20.
First, the red light of the light emitted from the polarizing illumination device 1 transmits through a blue-green reflecting dichroic mirror 401 serving as the colored light separating means, and the blue light and the green light are reflected. The red light is reflected by a reflecting mirror 403 and reaches a liquid crystal device 411 for red light. On the other hand, the green light of the blue and green lights is reflected by a green reflecting dichroic mirror 402 that also serves as the colored light separating means, and reaches a liquid crystal device 412 for green light.
Since the blue light has the longest optical path of the colored lights, a light guide means 430 formed of a relay lens system comprising an incident lens 431, a relay lens 432, and an emergent lens 433 is provided for the blue light. That is, after transmitting through the green reflecting dichroic mirror 402 and the incident lens 431, the blue light is first reflected by a reflecting mirror 435, and directed to and focused onto the relay lens 432. After being focused onto the relay lens, the blue light is directed to the emergent lens 433 by a reflecting mirror 436, and then, reaches a liquid crystal device 413 for blue light. The liquid crystal devices 411, 412, and 413 located at three positions respectively modulate the colored lights so that the colored lights contain corresponding image information, and make the modulated colored lights enter a crossed dichroic prism 450 serving as the colored light synthesizing means. The crossed dichroic prism 450 includes a dielectric multilayer film for reflecting red light and a dielectric multilayer film for reflecting blue light which are crossed in the form of X, and synthesizing the modulated light beams, thereby forming a color image. The color image formed therein is enlarged and projected onto a screen 470 by a projection lens 460 serving as the projection optical system, so that a projection image is formed.
The projection display apparatus projector 3 having such a structure employs the liquid crystal devices each for modulating one type of polarized beam. Therefore, if randomly polarized beams are directed to the liquid crystal device by using a conventional illumination device, about half of them are absorbed by a polarizing plate (not shown) and turned into heat. Therefore, the light use efficiency is low, and there is a need for a large and noisy cooling device for minimizing heat generation of the polarizing plate. The projection display apparatus projector 3 of this embodiment, however, substantially improves such problems.
In the polarizing illumination device 1 of the projection display apparatus projector 3 according to this embodiment, only one type of polarized beam, for example, a P polarized beam is subjected to the rotary polarization action by a λ/2 phase plate, and the polarization direction thereof is made identical with that of the other type of polarized beam, for example, and S polarized beam. Since substantially the same type of polarized beams, which are polarized in the same direction, are directed to the liquid crystal devices 411, 412, and 413 located at three position, the amount of light to be absorbed by the polarizing plate is extremely small, which makes it possible to enhance the light use efficiency, and to thereby obtain a bright projection image.
Particularly, in the polarizing illumination device 1 used as an illumination device, since the shading plate 370 is placed inside the second optical element 300, other polarized beams which are unnecessary for display on the liquid crystal device rarely mix into the illumination light emitted from the polarizing illumination device 1. As a result, the amount of light absorbed by polarizing plates (not shown) respectively placed on the light incident sides of the liquid crystal devices 411, 412, and 413 located at three positions is extremely small, and therefore, the amount of heat generated in light absorption is extremely small. Consequently, it is possible to substantially reduce the size of a cooling device for minimizing the increase in temperature of the polarizing plates and the liquid crystal devices. As mentioned above, a small cooling device will do for a projection display apparatus projector capable of displaying a considerably bright projection image with a considerably high-power light source lamp, which makes it possible to reduce noise of the cooling device, and to thereby achieve a quiet and high-performance projection display apparatus projector.
Furthermore, the polarizing illumination device 1 spatially separates two types of polarized beams in the lateral direction (the X direction) by the second optical element 300. Therefore, the polarizing illumination device 1 does not waste the light, and is convenient for illuminating a liquid crystal device shaped like a laterally extended rectangle.
As described in connection with the above described first embodiment, the widening of light beams emitted from the polarizing separation unit array 320 is restricted although the polarizing illumination device 1 of this embodiment incorporates polarizing conversion optical elements therein. This means that minimal light enters the liquid crystal device at a large angle in illuminating the liquid crystal device. Accordingly, it is possible to achieve a bright projection image without using a projection lens system having a small F-number and an extremely large aperture, and to thereby achieve a compact projection display apparatus projector.
Since the crossed dichroic prism 450 is used as the colored light synthesizing means in this embodiment, it is possible to reduce the size of the apparatus. Furthermore, since the optical paths between the liquid crystal devices 411, 412, and 413, and the projection lens system are short, even if the projection lens system has a relatively small aperture, it is possible to achieve a bright projection image. Still furthermore, though only one of the three optical paths of the colored lights is difficult in length from the others, since the light guide means 430 formed of a relay lens system comprising the incident lens 431, the relay lens 432, and the emergent lens 433 is provided for the blue light having the longest optical path, no color inconsistency arises.
The projection display apparatus projector may comprise a mirror optical system using two dichroic mirrors as the colored light synthesizing means. Of course, it is also possible in that case to incorporate the polarizing illumination device of this embodiment, and to form a high-quality bright projection image having a high light use efficiency, similarly to this embodiment.
Another embodiment of a projection display apparatus projector in which the polarizing illumination device 1 described in the first embodiment is incorporated will be described. In this embodiment, reflection-type liquid crystal devices are used as modulating devices for modulating light beams emitted from the polarizing illumination device according to display information.
The polarizing illumination device 1 has a light source section 10 for emitting randomly polarized beams in one direction, and the randomly polarized beams emitted from the light source section 10 are converted into substantially the same type of polarized beams (S polarized beams in this embodiment) by a polarized light generating device 20.
The light beams emitted from the polarizing illumination device 1 enter into the polarizing beam splitter 480, and are reflected by a polarizing separation plane 418. Then, the traveling direction of the light beams is changed by approximately 90°. Then, the light beams enter the adjoining crossed dichroic prism 450. Although most of the light beams emitted from the polarizing illumination device 1 are S polarized beams, a few polarized beams polarized in a different direction from the S polarized beams (P polarized beams in this embodiment) sometimes mix, and the light beams polarized in the different direction (the P polarized beams) transmit through the polarizing separation plane 481 unchanged, and are emitted from the polarizing beam splitter 480 (these P polarized beams do not serve as illumination light for illuminating the liquid crystal devices.)
The S polarized beams that are incident on the crossed dichroic prism 450 are separated into three light beams of red, green, and blue by the crossed dichroic prism 450 in accordance with the wavelength, and the light beams respectively reach the reflection liquid crystal device 414 for red light, the reflection liquid crystal device 415 for green light, and the reflection liquid crystal device 416 for blue light, thereby illuminating the liquid crystal devices. That is, the crossed dichroic prism 450 acts as the colored light separation means for illumination light for illuminating the liquid crystal devices.
The liquid crystal devices 414, 415, and 416 used in this embodiment are of the reflection-type. They modulate respective colored lights, and provide the colored lights with corresponding external display information. At the same time, they respectively change the polarization directions of the light beams emitted from the liquid crystal devices, and almost reverse the direction of travel of the light beams. Therefore, the light beams respectively reflected from the liquid crystal devices are partially brought to a P polarized state according to display information, and then emitted. The modulated light beams emitted from the liquid crystal devices 414, 415, and 416 (mainly P polarized beams) enter the crossed dichroic prism 450 again, are synthesized into one optical image, and enter the adjoining polarizing beam splitter 480 again. That is, the crossed dichroic prism 450 acts as the colored light synthesizing means for the modulated light beams emitted from the liquid crystal devices.
Since the light beams modulated by the liquid crystal devices 414, 415, and 416 of the light beams that are incident on the polarizing beam splitter 480 are P polarized beams, they transmit through the polarizing separation plane 481 of the polarizing beam splitter 480 unchanged, and form an image on a screen 470 through the projection lens 460.
The projection display apparatus projector 4 having such a structure also employs liquid crystal devices that each modulate one type of polarized beam, similarly to the above described projection display apparatus projector 3. Therefore, when a conventional illumination device for using randomly polarized beams as illumination light is employed, light beams separated by the polarizing beam splitter 480 and directed to the reflection-type liquid crystal devices are reduced to approximately half the number of the randomly polarized beams, the light use efficiency is low and a bright projection image is difficult to obtain. In the projection display apparatus projector 4 of this embodiment, however, such a problem is substantially improved.
That is, the projection display apparatus projector 4 of this embodiment can efficiently generate substantially the same type of polarized beams, they are polarized in the same direction, by using the polarizing illumination device 1 of the present invention instead of the conventional illumination device, and therefore, almost all light beams that are incident on the polarizing beam splitter 480 are directed as illumination light beams to the reflection-type liquid crystal devices 414, 415, and 416 located at three positions. As a result, it is possible to obtain a bright projection image that is uniform in brightness and color.
Particularly, in the polarizing illumination device 1 used as an illumination device, since the shading plate 370 is placed inside the second optical element 300, other polarized beams that are unnecessary for display on the liquid crystal apparatus hardly mix into the illumination light emitted from the polarizing illumination device 1. Therefore, it is possible to obtain high-quality illumination light beams polarized in the same direction, and to thereby succeed in obtaining a high-quality bright projection image.
Moreover, the second optical element 300 in the polarizing illumination device 1 spatially separates two types of polarized beams in the lateral direction (the X direction). Therefore, the polarizing illumination device 1 does not waste the light and is convenient for illuminating a liquid crystal device shaped like a laterally extended rectangle.
As described in connection with the above described first embodiment, the widening of light beams emitted from the polarizing separation unit array 320 is restricted although the polarizing illumination device 1 of this embodiment incorporates polarizing conversion optical elements therein. This means that minimal light enters the liquid crystal device at a large angle in illuminating the liquid crystal device. Accordingly, it is possible to achieve a bright projection image without using a projection lens system having a small F-number and an extremely large aperture, and to thereby achieve a compact projection display apparatus projector .
Condenser lenses 417 may be respectively interposed between the crossed dichroic prism 450 and the liquid crystal devices 414, 415, and 416 located at three positions in the projection display apparatus projector 4 of this embodiment.
Although S polarized beams are used as illumination light in the projection display apparatus projector 4 of this embodiment. P polarized beams may be used as illumination light. In this case, the polarizing illumination device 1 and the crossed dichroic prism 450 are placed opposed to each other through the polarizing beam splitter 480.
Furthermore, though the crossed dichroic prism is used as the colored light separation means and the colored light synthesizing means in the embodiment, the projection display apparatus projector may comprise two dichroic mirrors instead. Of course, it is also possible in that case to incorporate the polarizing illumination device of this embodiment, and to form a high-quality bright projection image having a high light use efficiency, similarly to this embodiment.
As described above, according to the present invention, it is possible to achieve a polarizing conversion device and a polarizing illumination device capable of generating with high efficiency only the same type of polarized beams that have a more uniform light intensity distribution in a illumination region than incident light beams, and, at the same, that are polarized in the same direction. Furthermore, it is possible to easily achieve a display apparatus and a projection display apparatus projector capable of displaying a high-quality bright image through the use of the polarizing conversion device and the polarizing illumination device of the present invention.
Itoh, Yoshitaka, Hashizume, Toshiaki
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