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Projection type liquid-crystal video display device using a fresnel lens

  • US 4,936,657 A
  • Filed: 07/18/1986
  • Issued: 06/26/1990
  • Est. Priority Date: 07/18/1985
  • Status: Expired due to Term
First Claim
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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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