Automatic liquid-crystal light shutter

  • US 4,491,390 A
  • Filed: 05/06/1982
  • Issued: 01/01/1985
  • Est. Priority Date: 05/06/1982
  • Status: Expired due to Fees
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First Claim
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1. An automatic light-responsive light shutter comprising:

  • light shutter means responsive to application of a control signal at a first level for passing light therethrough along a first path and responsive to application of said control signal at a second level for highly attenuating light passing therethrough along said first path;

    first light responsive means for sensing intensity of direct light which strikes said light shutter means generally along said first path;

    second light responsive means for sensing intensity of side light which strikes said light shutter means generally perpendicular to said first path;

    circuit means for providing a comparison signal at a level which is a function of the relative intensities of direct and side light sensed at said first and second light responsive means, respectively; and

    control means responsive to said comparison signal for applying said control signal to said light shutter means at said first level when said comparison signal level is within a first predetermined range of levels, and for applying said control signal to said light shutter means at said second level when the comparison signal level is within a second predetermined range of levels, said first and second predetermined ranges of levels being substantially adjacent one another.

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