Optical: systems and elements – Optical modulator – Light wave temporal modulation
Reexamination Certificate
2003-06-12
2004-11-16
Epps, Georgia (Department: 2873)
Optical: systems and elements
Optical modulator
Light wave temporal modulation
C359S249000, C359S259000, C349S008000, C349S058000, C349S161000, C353S052000
Reexamination Certificate
active
06819464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical modulator for modulating a light beam irradiated by a light source in accordance with image information, and an optical device and a projector having the optical modulator.
2. Description of Related Art
Conventionally, a projector having a light source, an optical device for modulating a light beam irradiated by the light source in accordance with image information and a projection optical system for enlarging and projecting the light beam modulated by the optical device has been known as an optical equipment using an optical device (see Japanese Patent Laid-Open Publication No. 2000-89364).
The optical device of the projector has three optical modulators for modulating color light in accordance with image information, and a color combining optical system for combining respective light beams modulated by the optical modulators to form an optical image.
The optical modulator has an optical modulator body having a pair of substrates sealing an electrooptic material such as liquid crystal therebetween and a holding frame for accommodating and holding the optical modulator body.
The pair of substrates of the optical modulator body includes a first substrate on which a data line, a scan line, a switching element, a picture electrode etc. for applying driving voltage to the electrooptic material are formed, and a second substrate on which a common electrode, a black mask, and a color filter as necessary are formed.
The holding frame has an accommodating portion for accommodating the optical modulator body, and a fixing plate for positioning the optical modulator body inside the accommodating portion. The optical modulator body is accommodated in the holding frame with one of the substrates facing to the side of the accommodating portion of the holding frame and, subsequently, the optical modulator body is pressed by the fixing plate from the side of the other substrate.
In such optical modulator, the data line and scan line formed on the first substrate and the black mask formed on the second substrate etc. absorbs the heat generated by irradiating the light beam from the light source, thereby raising the temperature of the first and the second substrates. Accordingly, the heat of the substrates has to be released.
The substrate disposed on the accommodating portion side contacts with the accommodating portion on a large area, the heat can be efficiently released by constructing the accommodating portion with a heat-conductive material such as metal.
However, heat of the substrate located on the side of the fixing plate cannot be efficiently released, because the fixing plate is constructed by a thin plate and therefore has small heat capacity and the fixing plate only partially contacts with the substrate to press and hold the substrate.
Though it is possible to thicken the fixing plate to increase the heat capacity of the fixing plate, such arrangement inevitably increases the thickness of the optical modulator and the size of the optical device provided with the optical modulator, so that size reduction cannot be achieved. Further, since the gap against an optical element disposed on the downstream of the optical modulator such as a polarization plate is enlarged, image quality such as color evenness and contrast may be deteriorated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical modulator without deteriorating image quality and capable of improving heat releasing ability of the substrate, an optical device and a projector having the optical modulator.
An optical modulator according to an aspect of the present invention modulates a light beam irradiated by a light source in accordance with image information, the optical modulator including: an optical modulator body having a pair of transparent substrates between which an electrooptic material is sealed; a holding frame having an accommodating portion that accommodates the optical modulator body and a fixing plate that presses and holds the optical modulator body within the accommodating portion; and a frame member made of a heat-conductive material and provided on an outer periphery of a first substrate of the pair of substrates disposed on the side of the fixing plate, the frame member being in contact with the accommodating portion and/or the fixing plate.
The frame member may only be in contact with the accommodating portion of the holding frame or may only be in contact with the fixing plate. Alternatively, the frame member may be in contact with both of the accommodating portion and the fixing plate.
According to the above arrangement, since the frame member made of heat-conductive material is disposed on the outer periphery of the fist substrate of the optical modulator, the heat of the first substrate can be efficiently transferred to the frame member. Since the frame member is in contact with the holding frame, the heat transferred to the frame member is released to the outside through the holding frame. The provision of the frame member made of heat-conductive material allows efficient heat releasing from the first substrate to the holding frame, thus enhancing heat-releasing ability of the first substrate.
Further, since excellent heat-releasing ability can be obtained by providing the frame member, there is no need for increasing the thickness of the fixing plate in order to increase the heat capacity of the fixing plate, thus avoiding deterioration of image quality.
In the optical modulator of the above aspect of the present invention, the fixing plate and the frame member may preferably be integrally formed.
The fixing plate and the frame member may be integrated after constructing separate components and bonding the components with an adhesive etc. or may be integrated by welding etc. Alternatively, the fixing plate and the frame member may be an integrated molding formed by injection molding process etc.
According to the above arrangement, since the frame member made of heat-conductive material is disposed on the outer periphery of the first substrate of the optical modulator, the heat generated on the first substrate can be efficiently transferred to the frame member. Further, since the frame member is formed integrally with the fixing plate, sufficient contact area between the frame member and the fixing plate can be secured, thus releasing the heat generated on the first substrate toward the outside through a heat conduction channel from the frame member to the fixing plate. Accordingly, heat-releasing ability of the optical modulator body can be improved, thus lengthening the life of the optical modulator. Further, since the heat-releasing ability of the optical modulator body can be enhanced, there is no need for increasing the thickness of the fixing plate to increase the heat capacity of the fixing plate, thus avoiding deterioration of image quality.
In the optical modulator of the above aspect of the present invention, the fixing plate and the frame member may preferably be made of a heat-conductive metal or a heat-conductive resin.
The heat-conductive metal may be steel-nickel alloy such as Invar and 42Ni—Fe, magnesium alloy and aluminum alloy.
The heat-conductive resin may be a resin (polycarbonate, polyphenylene sulfide, liquid crystal resin etc.) containing carbon filler such as carbon fiber and carbon nanotube.
According to the above arrangement, since the fixing plate and the frame member are made of heat-conductive metal or heat-conductive resin having excellent heat conductivity, the heat-releasing ability of the first substrate can be further enhanced by the heat conduction channel.
In the optical modulator according to the above aspect of the present invention, the thermal conductivity of the heat-conductive metal and the heat-conductive resin may preferably be not less than 10W/(m·K).
According to the above arrangement, the heat generated on the first substrate can be rapidly released through the heat conduction channel. Further, the material of the fixing plat
Fujimori Motoyuki
Yanagisawa Yoshiyuki
Dinh Jack
Epps Georgia
Oliff & Berridg,e PLC
Seiko Epson Corporation
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