Projection type liquid-crystal video display device using a fresnel lens
First Claim
Patent Images
1. A projection-type liquid-crystal video display device, comprising:
- an illuminating light source;
a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel;
a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and
an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof of Fresnel lens having an optical axis offset from an optical axis of said optical system.
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Abstract
A projection-type liquid-crystal display in which a Fresnel lens in placed on the exit side of the liquid crystal panel to focus the image toward a projection lens. Preferably, the Fresnel lens has a non-symmetric pattern so as to efficiently gather light propagating through the display panel at an oblique angle coinciding with a reorientation angle of the liquid crystal. Additional optics on the incident side of the panel, perhaps including another non-symmetric Fresnel lens, collimates the light at the oblique angle.
133 Citations
25 Claims
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1. A projection-type liquid-crystal video display device, comprising:
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an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof of Fresnel lens having an optical axis offset from an optical axis of said optical system. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A projection-type liquid-crystal video display device, comprising:
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an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of light crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; and an optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other. - View Dependent Claims (9, 10)
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11. A projection-type liquid-crystal video display device, comprising:
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an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals of said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed adjacent on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having on at least one surface thereof a Fresnel lens having an optical axis offset from an optical axis of said optical system; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A projection-type liquid-crystal video display device, comprising:
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an illuminating light source; a nematic liquid-crystal display panel for transmitting said illuminating light, a reorientation angle of axes of liquid crystals in said display panel being inclined at a predetermined angle with respect to electrodes when a voltage is applied to said display panel; a projection optical system for projecting said transmitted light onto a screen, said optical system having an entrance pupil; a first optical element disposed on an emergence side of said liquid crystal panel for refracting the light emitted obliquely relative to said liquid crystal display in accordance with said reorientation angle of said liquid crystals, to optically converge the light in close proximity of said entrance pupil of said optical system, said optical element having a circular Fresnel lens on one surface and a stepped prism with a saw-toothed cross-section on the other; and a second optical element disposed on incident side of said liquid crystal panel for introducing the light, emitted from said illuminating light source, into said crystal display panel substantially in parallel with the reorientation angle of axes of the liquid crystals.
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Specification