Optics: image projectors – Color filter
Reexamination Certificate
2003-02-05
2004-04-27
Adams, Russell (Department: 2851)
Optics: image projectors
Color filter
C353S031000, C353S038000, C359S891000
Reexamination Certificate
active
06726334
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an illuminator which emits trichromatic light including components whose wavelengths correspond to three primary colors: red, green and blue, respectively, and a projector type image display apparatus which projects the trichromatic light emitted from the illuminator to display a color image.
BACKGROUND ART
Heretofore, there have been proposed projector type image display apparatuses in which white light is separated by color separation mirrors (dichroic mirror) into components of three primary colors: red (R), green (G) and blue (B) and these R, G and B light components are incident upon three image display panels, such as liquid crystal display (LCD) panel, respectively, the light components having passed through the image display panels are combined to produce synthetic light, and the synthetic light is projected onto a screen.
In the above projector type image display apparatuses, it is possible to adjust the white chromaticity or white balance of the projected light by adjusting the ratio in amount among the primary-color light components. One of the methods of adjusting the ratio in amount among the primary-color light components is to vary the electrically driven level of the display device for each primary-color channel from one channel to another.
However, this method is not advantageous in that it is necessary to lower the electrically driven level of the display device for a channel to be attenuated and the contrast of the channel for which the driven level has been lowered will be lower.
To prevent the contrast from being lower, it has been proposed to provide a transmissive filter such as ND (neutral density) filter in the optical path of a channel to be attenuated. In this case, the contrast can be made higher than by the above-mentioned electrical adjustment since it is unnecessary to lower the electrically driven level of the display device for any channel not to be attenuated.
However, the above method needs as many optical attenuation means such as ND filters as the channels to be attenuated, which will result in a complicated construction of the apparatus, that is, in a larger number of parts and number of manufacturing steps. Also, it is not expectable that an image can be displayed with any higher contrast than that which can be assured when the electrically driven level of the liquid crystal panels is not lowered.
Therefore, there have not yet been implemented any illuminator and projector type image display apparatus, simply constructed and capable of adjusting the white chromaticity of a projected light and displaying an image with an improved contrast.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention has an object to overcome the above-mentioned drawbacks of the related art by providing an illuminator and projector type image display apparatus, simply constructed and capable of adjusting the white chromaticity of a projected light and displaying an image with an improved contrast.
The above object can be attained by providing an illuminator which emits trichromatic light including components whose wavelengths correspond to three primary colors, respectively, the apparatus including according to the present invention:
a light source to emit the trichromatic light; and
a wavelength-selective optical aperture filter formed from a plurality of lens elements, being provided at the side of the light source from which the trichromatic light goes out, and which consists of zones working as predetermined optical apertures, of which one selectively attenuates or shields a component of the trichromatic light, whose wavelength corresponds to at least one of the three primary colors, while the other zones allow the light components whose wavelengths correspond to the other primary colors to pass through.
The illuminator constructed as above uses the wavelength-selective optical aperture filter formed from a spectral filter such as a dichroic filter designed to have an optical aperture variable correspondingly to a wavelength of illumination light, and can thus limit a component of the illumination light, whose wavelength corresponds to a specific primary color, and freely adjust the intensity of that primary-color light.
Also the above object can be attained by providing an illuminator which emits trichromatic light including components whose wavelengths correspond to three primary colors, respectively, the apparatus including according to the present invention:
a light source to emit the trichromatic light;
a pair of fly-eye lenses each formed from a plurality of lens elements and which separates the trichromatic light emitted from the light source into primary-color light components and allows the separated primary-color light components to pass through the plurality of lens elements, thereby uniformizing the trichromatic light output; and
a wavelength-selective optical aperture filter provided adjacent to one of the fly-eye lenses that is farther from the light source and which consists of zones working as predetermined apertures, of which one selectively attenuates or shields a component of the trichromatic light, whose wavelength corresponds to at least one of the three primary colors, while the other zones allow the light components whose wavelengths correspond to the other primary colors to pass through.
The illuminator constructed as above uses the wavelength-selective optical aperture filter formed from a spectral filter such as a dichroic filter designed to have an optical aperture variable correspondingly to a wavelength of illumination light, and can thus limit a component of the illumination light, whose wavelength corresponds to a specific primary color, and freely adjust the intensity of that primary-color light.
Also the above object can be attained by providing a projector type image display apparatus including according to the present invention:
an illuminator including:
a light source to emit trichromatic light; and
a wavelength-selective optical aperture filter provided at the side of the light source from which the trichromatic light goes out and which consists of zones working as predetermined apertures, of which one selectively attenuates or shields a component of the trichromatic light, whose wavelength corresponds to at least one of the three primary colors, while the other zones allow the light components whose wavelengths correspond to the other primary colors to pass through; and
a color separation means for separating the trichromatic light output from the wavelength-selective optical aperture filter into components whose wavelengths correspond to the three primary colors, respectively;
three image display panels to modulate, according to a video signal, the light components separated by the color separation means and whose wavelengths correspond to the three primary colors, respectively;
a color synthesis means for combining together the light components modulated by the three image display panels and whose wavelengths correspond to the three primary colors, respectively, to produce synthetic light; and
a projection lens to project the synthetic light from the color synthesis means onto a screen.
In the projector type image display apparatus constructed as above, the illuminator uses the wavelength-selective optical aperture filter formed from a spectral filter such as a dichroic filter designed to have an optical aperture variable correspondingly to a wavelength of illumination light, and thus can limit a component of the illumination light, whose wavelength corresponds to a specific primary color, and freely adjust the intensity of that light.
Also the above object can be attained by providing a projector type image display apparatus including according to the present invention:
an illuminator including:
a light source to emit trichromatic light;
a pair of fly-eye lenses each formed from a plurality of lens elements and which separates the trichromatic light emitted from the light source into primary-color light components and allows the separated primary-color light com
Adams Russell
Frommer William S.
Frommer & Lawrence & Haug LLP
Sever Andrew
Sony Corporation
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