Optics: image projectors – Miscellaneous
Patent
1992-10-21
1995-05-23
Cuchlinski, Jr., William A.
Optics: image projectors
Miscellaneous
353 34, 353 58, G03B 2100
Patent
active
054185866
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a projection type liquid crystal projector for separating white light obtained from for example a video tape into three primary colors, forming images with liquid crystal panels (liquid crystal light valves), mixing the images, and projecting an enlarged picture with a projection lens.
RELATED ARTS
In a conventional projection type liquid crystal projector as disclosed in Japanese Patent Laid-Open Publication Serial No. SHO 63-247720, white light is separated into three primary colors with dichroic mirrors. With liquid crystal light valves respective images of these colors are formed. Thereafter, with an image mixing mirror, these images are mixed. Next, with a projection lens, the mixed image is enlarged and then projected.
With the above-mentioned projection type liquid crystal projector, pixel positions of the liquid crystal light valves, which form blue, green, and red images, cannot be relatively adjusted. In addition, due to deviation of the mounting angles of reflection mirrors disposed in the respective optical paths to the projection lens, the optical axis is deviated. Moreover, due to deviation of the mounting angles of the liquid crystal light valves to their optical axes, when the three primary colors are mixed, the resultant image is deviated. The deviations of positions of the liquid crystal light valves for blue, green, and red colors to the projection lens result in an out-of-focus image. As a result, the quality of picture being projected is deteriorated.
To solve these problems, the mounting position and the mounting angle of the liquid crystal light valve for each color should be adjusted. Nevertheless, in the conventional apparatuses, only a means for moving the mounting positions with eccentric pins or adjustment screws is provided. However, in the apparatus where the positions of the liquid crystal light valves are adjusted with the eccentric pins, the rotating direction of the eccentric pin and the moving direction of each liquid crystal light valve are not uniformly determined. Thus, the adjustment of movement to a desired direction is very difficult to do. In addition, the eccentric pins are not easy to machine. Moreover, E rings, nuts, and so forth are required to secure the eccentric pins. Consequently, the number of parts increases and the assembling work takes a long time, resulting in raising the production cost of the apparatus.
On the other hand, so far, the conventional liquid crystal light valves are designed and produced for use in designated colors. In particular, the specifications of the liquid crystal light valves for forming a green image whose relative visibility is high are severe. In contrast, the specifications of the liquid crystal light valve for forming a blue image whose specific visibility is low are comparatively less severe. Thus, even if a liquid crystal light valve which can be satisfactorily used for blue color cannot be used for green color. Therefore, in this situation, this valve should be treated as an unacceptable item. Consequently, the yield of these liquid crystal light valves is low, thereby raising the production cost.
In addition, the conventional projection type liquid crystal projector is provided with two fans which are an air intake fan and an air exhaust fan as cooling means. With these fans, the interior of the apparatus is cooled. However, lacking sufficient analysis of the air flow paths and so forth, the spherical portion of a light source (metal halide lamp), an UV and IR filter portion, a polarizing plate, a liquid crystal panel, electric parts for an exhaust opening, electric devices, and so forth are not satisfactorily cooled. Thus, these constructional parts are heated to temperatures close to their limit values. On the other hand, there are demands of brighter projectors of low-noise in the marketplace. However, the conventional cooling means cannot satisfy such demands. Unless the above-mentioned constructional parts are satisfactorily cooled, problems such as deteriorating
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patent: 5092671 (1992-03-01), Van Os
patent: 5231431 (1993-07-01), Yano et al.
patent: 5237399 (1993-08-01), Inada et al.
Fujimori Motoyuki
Hashizume Toshiaki
Iguchi Kenji
Okumura Kiichi
Sakagami Keisuke
Cuchlinski Jr. William A.
Dowling William C.
Seiko Epson Corporation
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