Optics: image projectors – Housing
Reexamination Certificate
2000-03-14
2002-08-06
Adams, Russell (Department: 2851)
Optics: image projectors
Housing
C353S056000, C353S057000, C353S060000, C349S005000
Reexamination Certificate
active
06428170
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a projector including an electrooptical device for forming an optical image according to image information, and a projection lens for enlarging and projecting the image formed by the electrooptical device.
2. Description of Related Art
Hitherto, projectors have been used which include a light source, an optical system for modulating light emitted from the light source according to image information to form an optical image, and a projection lens for enlarging and projecting the modulated light. The optical system includes an illuminating optical system for producing a uniform inplane illumination distribution of light emitted from the light source, a color separation optical system for separating the light from the illuminating optical system into three primary colors of red, blue, and green, an electrooptical device for modulating color lights according to image information, and a color-synthesizing optical system for synthesizing the modulated color lights. The electrooptical device includes three optical modulation devices for modulating each of a red light, a blue light, and a green light separated by the color separation optical system according to image information.
As such an optical modulation device, for example, a liquid crystal panel or the like using a polysilicon TFT as a switching element is used. Since the optical modulation devices are important portions for forming an optical image according to image information, if dust or oil mist adheres to the surface of the liquid crystal panel or the like, the image quality of the projector will deteriorate. For this reason, a projector including an enclosing structure for enclosing an optical path from the electrooptical device to the projection lens may be adopted. Since such a projector including the enclosing structure can prevent the entry of dust or oil mist from the outside by the enclosing structure, dust or oil mist does not adhere to the surface of the liquid crystal panel, the image quality of the projector can be stably secured over a long period of time, and the projector is suitably used as a stationary projector device, such as a hanging-type projector.
However, since the optical modulation device, such as the liquid crystal panel, is easily affected by heat, if the optical path from the electrooptical device to the projection lens is enclosed by the enclosing structure as described above, it is difficult to efficiently cool the optical modulation device, i.e., the electrooptical device by introducing cooling air from the outside of the device. In particular, in a recent trend toward an increase in brightness and a reduction in size of the projector, efficiently cooling the electrooptical device is an important problem.
It is an object of the present invention to provide a projector that is able to efficiently cool an electrooptical device, and to stably secure the image quality over a long period of time.
SUMMARY OF THE INVENTION
The present invention provides a projector which may consist of an electrooptical device for forming an optical image according to image information; and a projection lens for enlarging and projecting the image formed by the electrooptical device; wherein the projector includes an enclosing structure that encloses an optical path from the electrooptical device to the projection lens with a heat insulating member, and a cooling element for cooling the air inside the enclosing structure.
As the heat insulating member, a member formed of plastic, glass fiber, asbestos, or suberin may be employed.
In the present invention as described above, the optical path from the electrooptical device to the projection lens is enclosed by the enclosing structure, and the air inside the enclosing structure is cooled by the cooling element, whereby the electrooptical device can be efficiently cooled. In addition, since the entry of dust or oil mist from the outside is prevented by the enclosing structure, the dust or oil mist does not adhere to the electrooptical device and the like, and the image quality of the projector can be stably secured over a long period of time.
Furthermore, since the enclosing structure is formed by the heat insulating member, the inside and the outside of the enclosing structure are thermally blocked, whereby cooling efficiency of the cooling element is further improved, and dew condensation or the like does not occur.
In the foregoing, a circulating fan for circulating the air inside the enclosing structure may preferably be provided inside the enclosing structure.
This allows the circulating fan to forcibly circulate the air inside the enclosing structure, whereby the electrooptical device can be cooled more efficiently.
In addition, the above-described cooling element may preferably be a thermoelectric transducer including a heat absorption surface facing the inside of the enclosing structure and a heat radiation surface facing the outside of the enclosing structure.
As the thermoelectric transducer, a Peltier element may be adopted by which a phenomenon occurs such that, if two different types of metal or semiconductors are electrically joined in series and a direct current is passed therethrough, heat absorption and heat radiation other than Joule heat occur on the joint thereof.
With this configuration, by exposing the heat absorption surface of the thermoelectric transducer to the inside of the enclosing structure and exposing the heat radiation surface to the outside of the enclosing structure, heat included in the air inside the enclosing structure can be easily radiated to the outside of the enclosing structure, whereby the structure of the cooling element can be simplified and reduced in size.
Furthermore, the heat absorption surface and/or the heat radiation surface may preferably be provided with heat transfer members, each having heat transference.
As the heat transfer member provided on the heat absorption surface, a plate-like member made of aluminum or the like can be employed, and as the heat transfer member provided on the heat radiation surface, a heat radiating fin made of aluminum or the like can be employed.
If the heat absorption surface is provided with the transfer member in this way, by disposing the heat transfer member in an airflow inside the enclosing structure, heat exchange between the internal air and the heat transfer member is smoothly affected, and the heat inside the enclosing structure can be efficiently transferred to the heat absorption surface.
If the heat radiation surface is provided with the heat transfer member, heat can be efficiently radiated from the heat transfer member when the heat is radiated to the outside of the enclosing structure from the heat radiation surface. That is, by providing the heat transfer members on the heat absorption surface and the heat radiation surface, heat absorption operation and heat radiation operation of the thermoelectric transducer can be efficiently affected.
In addition, a cooling fan for cooling the heat transfer members may preferably be provided at a position opposing the heat transfer member provided on the heat radiation surface.
This allows a heat transfer member to be forcibly cooled. Therefore, the temperature rise inside the device due to the heat radiation from the heat transfer member can be prevented. In addition, since the heat transfer member is forcibly cooled, heat is efficiently transferred from the heat radiation surface to the heat transfer member, and heat radiation operation of the thermoelectric transducer is efficiently affected also in this respect.
REFERENCES:
patent: 5676442 (1997-10-01), Fujimori
patent: 5803566 (1998-09-01), Ogino
patent: 6085055 (2000-07-01), Shin et al.
patent: 6231191 (2001-05-01), Shiraishi et al.
Adams Russell
Koval Melissa J
Seiko Epson Corporation
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