Graphics input tablet with three-dimensional data

  • US 4,798,919 A
  • Filed: 03/11/1988
  • Issued: 01/17/1989
  • Est. Priority Date: 04/28/1987
  • Status: Expired due to Term
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First Claim
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1. A graphics input tablet comprising a layer of electrically resistive material (10) supported co-extensively with a layer of electrically conductive material (11) to provide a flat tablet surface, the resistive material having the property that the electrical resistance between the layers in the region of localized pressure applied thereto changes monotonically with the applied pressure, first and second conductors (14,15) connected respectively to first and second portions of the resistive layer (18,19), said portions being spaced apart on a first notional line across the tablet surface, the construction and arrangement being such that with an electrical potential applied between the resistive layer and the conductive layer substantially no current flows through said first and second conductors, but with said localized pressure applied to said tablet surface currents flow through said first and second conductors, the relative magnitudes of the currents being related to the respective distances of the region of applied pressure from the first and second portions and the total current flowing between the resistive sheet and the conductive sheet being related to the magnitude of the applied pressure.

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