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Liquid crystal position determining system and wand device

  • US 4,977,315 A
  • Filed: 10/06/1989
  • Issued: 12/11/1990
  • Est. Priority Date: 10/06/1989
  • Status: Expired due to Fees
First Claim
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1. A position determining system comprising:

  • a tablet having a plurality of coplanar spaced substantially transparent first conductor strips, a plurality of coplanar spaced substantially transparent second conductor strips, the plane of said first strips being parallel to and spaced from the plane of said second strips, and a liquid crystal material between said first and second strips;

    means for scanning said conductor strips to cause a dark line to propagate across the tablet surface;

    said tablet being at least partially light transmissive substantially throughout its extent such that objects on one side of said tablet are visible from its opposite side;

    a wand-type device connected to the system and positionable by a user over its opposite side;

    p1 means connected to the wand-type device for detecting when a dark line crosses under the wand-type device.

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