Optics: image projectors – Miscellaneous
Reexamination Certificate
2002-03-18
2003-09-23
Adams, Russell (Department: 2851)
Optics: image projectors
Miscellaneous
C353S020000, C353S030000, C353S031000, C353S057000, C353S061000, C349S005000
Reexamination Certificate
active
06623129
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a projector for projecting and displaying of an image, and in particular to an optical component used in a projector.
2. Description of the Related Art
Projectors display images by modulating light from an illumination optical system in response to image information (image signal) by means of a liquid crystal panel, and projecting the modulated light onto a screen.
Optical components in projectors typically have surfaces formed of glass, and thus have the drawback of being susceptible to soiling. This is because the surface of an insulator such as glass is susceptible to becoming statically charged. The charged surface of an insulator attracts dust by static electricity. Dust adhering to the surface of an optical component soils the surface of the optical component. Electrically driven optical components such as liquid crystal panels are especially susceptible to buildup of static charge on the surface, so the above problem is particularly severe in liquid crystal panels.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a technique for reducing surface soiling of optical components used in projectors and other devices.
At least part of the above and the other related objects is attained by an optical component as a first device of the present invention. The optical component comprises: a light transmissive member; and a light transmissive film formed on the light transmissive member. The light transmissive film includes: a semiconductor photocatalyst film constituting the outside surface of the optical component; and an antistatic film formed between the semiconductor photocatalyst film and the light transmissive member.
Herein, the term “antistatic film” includes not only films that prevent buildup of static charge, but also films that reduce static charge.
This optical component is provided with a light transmissive film including an antistatic film and a semiconductor photocatalyst film. It is accordingly possible to reduce static charge on the surface of the optical component, so as to reduce adhesion of dust to the surface of the optical component. When the optical component is illuminated with a light component capable of activating the semiconductor photocatalyst film, organic matter (dust) adhering to the surface of the optical component is decomposed, allowing organic matter (dust) adhering to the surface of the optical component to be cleared. As a result, it is possible to reduce soiling of the surface of the optical component.
In the above device, it is preferable that the semiconductor photocatalyst film contains TiO
2
.
By so doing, soiling of the optical component surface can be reduced more efficiently than is possible with semiconductor photocatalyst films containing other materials.
It is preferable that the TiO
2
is of anatase crystalline form.
In this case, soiling of the optical component surface can be reduced more efficiently than is possible with TiO
2
of rutile crystalline form.
In the above device, it is preferable that the antistatic film has surface resistivity of less than about 1.0×10
10
&OHgr;.
This arrangement affords effective functioning as an antistatic film.
In the above device, it is preferable that the semiconductor photocatalyst film is formed on the antistatic film, and the antistatic film includes an SiO
2
layer situated at the interface thereof with the semiconductor photocatalyst film.
SiO
2
is typically highly hydrophilic. Accordingly, with the above arrangement the SiO
2
layer can improve the hydrophilic function of the semiconductor photocatalyst film. Further, where the antistatic film contains organic matter, the SiO
2
layer can reduce deterioration of the antistatic film by activation of the semiconductor photocatalyst.
It is preferable that the antistatic film includes a transparent conductive layer.
In this case, the surface resistivity of the antistatic film can be brought to a relatively low level, and the transparency of the antistatic film is readily assured.
In the above device, it is preferable that the light transmissive film is formed at least in a specific region on which particular light designed to enter the optical component is to be incident.
By so doing, the light transmissive film can be formed over a relatively small area, thereby making fabrication of the optical component relatively easy.
The present invention is also directed to a second device that is a projector for projecting and displaying of an image. The projector comprises: an illumination optical system; an electro-optical device for modulating light from the illuminating optical system in response to image information; and a projection optical system for projecting the modulated light from the electro-optical device. At least one of a plurality of optical components arranged on the optical path from the illumination optical system to the projection optical system comprises: a light transmissive member; and a light transmissive film formed on the light transmissive member. The light transmissive film includes: a semiconductor photocatalyst film constituting the outside surface of the optical component; and an antistatic film formed between the semiconductor photocatalyst film and the light transmissive member.
This projector employs the first device of the present invention. It is accordingly possible to achieve functions and advantages similar to those obtained using the first device, and to reduce soiling of optical component surfaces. By incorporating the optical component herein into the projector, the efficiency of utilization of light in the projector can be improved.
In the above device, it is preferable that the illumination optical system includes a light source device for emitting light that includes a light component having a predetermined wavelength capable of activating the semiconductor photocatalyst film.
By so doing, light emitted from the light source device can be used to activate the semiconductor photocatalyst film formed on the surface of the optical component, obviating the need for a special light source device for this purpose.
In the above device, it is preferable that the electro-optical device is said optical component.
In this case, surface soiling of the electro-optical device, which is relatively more susceptible to becoming statically charged, can be reduced.
The above device may further comprises: an chassis for accommodating the plurality of optical components arranged on the optical path from the illumination optical system to the projection optical system; and at least one cooling fan for cooling interior of the chassis.
Where a cooling fan is provided, the optical component surface becomes more susceptible to static charge buildup due to the air flowing in proximity to the optical component surface. Accordingly, the advantages of the invention are particularly notable where a cooling fan is provided.
The above device may further comprises: a filter having a semiconductor photocatalyst affixed thereto, arranged at ventilation passage of the cooling fan.
By using a filter in this way, penetration of dust into the interior of the chassis can be reduced, thereby reducing soiling of optical component surfaces. Since the semiconductor photocatalyst affixed to the filter decomposes dust adhering to the filter, dust adhering to the filter can be cleared. As a result, clogging of the filter can be reduced, allowing the cooling fan to efficiently cool the interior of the chassis.
The present invention is also directed to a third device that is a projector for projecting and displaying of a color image. The projector comprises: an illumination optical system; a color separation optical system for separating light emitted from the illumination optical system into first through third colored lights; first through third electro-optical devices for modulating the first through third colored lights in response to image information to generate first through third modulated lights; a color combination optical
Adams Russell
Koval Melissa J
Oliff & Berridg,e PLC
Seiko Epson Corporation
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