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Digitale, an indicating device containing liquid crystals

  • US 4,104,627 A
  • Filed: 05/02/1975
  • Issued: 08/01/1978
  • Est. Priority Date: 05/03/1974
  • Status: Expired due to Term
First Claim
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1. A digital indicating device comprising:

  • a liquid crystal cell having first and second planar, approximately parallel, spaced-apart faces between which a liquid crystal showing optical rotary power is disposed, and a plurality of light transmissive, electrically conductive electrode pairs on opposite sides of the liquid crystal corresponding to character regions to be displayed, the first face of the cell being exposed to ambient light;

    first and second light polarizing means having directions of polarization at right angles to each other, the first and second light polarizing means being disposed adjacent to opposite sides of the liquid crystal cell parallel to the first and second planar faces thereof, respectively;

    light emitting means disposed adjacent to the second polarizing means on the side thereof opposite the second face of the cell to direct light through the cell toward the first face;

    a reflector disposed between the light emitting means and the second polarizing means, the reflector being light transmissive on the areas corresponding to the character regions;

    means for generating electrical control signals corresponding to the different characters to be displayed to impress an electrical potential difference across certain combinations of the electrode pairs to deactivate the liquid crystal between such electrode pairs;

    first means responsive to the control signals for displaying the corresponding characters as dark characters on a light background at the first face of the cell in the presence of ambient light incident upon the first face of the cell; and

    second means responsive to the control signals for displaying the same corresponding characters as light characters on a dark background at the first face of the cell in the absence of ambient light incident upon the first face of the cell.

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