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Transparent coordinate input apparatus for electrostatic capacity coupling system

  • US 5,083,118 A
  • Filed: 04/16/1990
  • Issued: 01/21/1992
  • Est. Priority Date: 04/16/1990
  • Status: Expired due to Term
First Claim
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1. A transparent coordinate input apparatus mounted on a display surface of a CRT, an LCD or the like to effect an input comprising:

  • a tablet composed of a first set of wider parallel electrode wires spaced apart from one another with narrow gaps therebetween and arranged close to the display surface and a second set of narrower parallel electrode wires arranged at an intersecting angle with and in front of the first set so that the wider electrode wires are closer to the display surface than the narrower electrode wires;

    a control section for sequentially applying pulse signals to said electrode wires of said tablet;

    coordinate indication means electrostatic-capacity coupled to the pulse signals applied to said electrode wires of said tablet to effect signal detection;

    calculation means for calculating a positional coordinate from the pulse signals detected by said coordinate indication means; and

    noise preventive means for relieving a noise from the display surface, the noise preventive means comprising a plurality of resistors each equivalently grounded to one end of one of said wider parallel electrode wires of said tablet;

    whereby the wider parallel electrode wires that are not applied with the pulse signals act as a shield to reduce the effects of noise emanating from the display surface on the coordinate indication means.

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