Liquid crystal projector including a polaration rotating element
First Claim
1. An image projector comprising:
- at least one source of light;
a liquid crystal matrix screen;
a polarization direction rotating element;
a polarization separator separating the light into first and second polarized beams having directions of polarization that are orthogonal with respect to each other, the first and second polarized beams being modulated by the liquid crystal matrix screen after one of said first and second polarized beams has passed through the polarization direction rotating element;
first means for achieving at least two reflections for each of said first and second polarized beams, said first means including first and second reflectors for reflecting the first and second polarized beams, respectively, toward an optical axis on which the liquid crystal matrix screen is centered and third and fourth reflectors for reflecting the first and second polarized beams, respectively, toward the liquid crystal matrix screen; and
second means for converging the first and second polarized beams on at least a part of the paths of the first and second polarized means between the polarization separator and the liquid crystal matrix screen, so that each of said first and second polarized beams forms an image of the light source between the third and fourth reflectors and the liquid crystal matrix screen.
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Accused Products
Abstract
Disclosed is an image projector of the type in which an LCD matrix screen is illuminated by two polarized beams after 90° rotation of the direction of polarization of one of these two beams. Each of the two polarized beams is reflected at least once towards an optical axis on which the matrix screen is centered and at least once again towards the matrix screen. Furthermore, the image projector has means to make each beam polarized, so that each polarized beam forms an image of the light source before illuminating the matrix screen. The two polarized beams may thus be oriented towards the matrix screen in forming a small angle with one another, thus enabling the use of a projection objective with a small aperture.
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Citations
21 Claims
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1. An image projector comprising:
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at least one source of light; a liquid crystal matrix screen; a polarization direction rotating element; a polarization separator separating the light into first and second polarized beams having directions of polarization that are orthogonal with respect to each other, the first and second polarized beams being modulated by the liquid crystal matrix screen after one of said first and second polarized beams has passed through the polarization direction rotating element; first means for achieving at least two reflections for each of said first and second polarized beams, said first means including first and second reflectors for reflecting the first and second polarized beams, respectively, toward an optical axis on which the liquid crystal matrix screen is centered and third and fourth reflectors for reflecting the first and second polarized beams, respectively, toward the liquid crystal matrix screen; and second means for converging the first and second polarized beams on at least a part of the paths of the first and second polarized means between the polarization separator and the liquid crystal matrix screen, so that each of said first and second polarized beams forms an image of the light source between the third and fourth reflectors and the liquid crystal matrix screen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An image projector comprising:
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a light source; a plurality of monochromatic devices, wherein each of said monochromatic devices includes; a liquid crystal matrix screen; a polarization direction rotating element; a polarization separator separating the light into first and second polarized beams having directions of polarization that are orthogonal with respect to each other, the first and second polarized beams being modulated by the liquid crystal matrix screen after one of said first and second polarized beams has passed through the polarization direction rotating element; first means for achieving at least two reflections for each of said first and second polarized beams, said first means including first and second reflectors for reflecting the first and second polarized beams toward an optical axis on which the liquid crystal matrix screen is centered and third and fourth reflectors for reflecting the respective first and second polarized beams toward the liquid crystal matrix screen; and second means for converging the first and second polarized beams on at least a part of the paths of the first and second polarized beams between the polarization separator and the liquid crystal matrix screen, so that each of said first and second polarized beams forms an image of the light source between the third and fourth reflectors and the liquid crystal matrix screen. - View Dependent Claims (13, 14, 17, 18, 19, 20)
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15. An image projector comprising:
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a light source; a plurality of modulator units, each including a liquid crystal matrix screen; and a separating-orienting unit including; a polarization direction rotating element; a polarization separator separating the light into first and second polarized beams having directions of polarization that are orthogonal with respect to each other, first and second polarized beams being modulated by the liquid crystal matrix screen after one of said first and second polarized beams has passed through the polarization direction rotating element; first means for achieving at least two reflections for each of said first and second polarized beams, said first means including first and second reflectors for reflecting the first and second polarized beams toward an optical axis on which the liquid crystal matrix screen is centered and third and fourth reflectors for reflecting the respective first and second polarized beams toward the liquid crystal matrix screen; and second means for converging the first and second polarized beams on at least a part of the paths of the first and second polarized beams between the polarization separator and the liquid crystal matrix screen, so that each of said first and second polarized beams forms an image of the light source between the third and fourth reflectors and the liquid crystal matrix screen. - View Dependent Claims (16, 21)
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Specification