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Data input device with a pressure-sensitive input surface

  • US 5,369,228 A
  • Filed: 11/25/1992
  • Issued: 11/29/1994
  • Est. Priority Date: 11/30/1991
  • Status: Expired due to Fees
First Claim
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1. A pressure sensitive data input device, comprisingan input surface adapted to be locally exposed to an amount of pressure at a pressure point,a resistive layer comprising at least two pairs of mutually spaced electrodes, each of the at least two pairs of mutually spaced electrodes being arranged in opposed, spaced relationship,a deformable layer arranged between the input surface and the resistive layer, the deformable layer comprising at least one of an electrically insulating layer and a dielectric layer, the deformable layer having a thickness that, when an amount of pressure is applied to the input surface at the pressure point, is locally reducible to a non-zero thickness at the pressure point,an electrode layer spaced from the resistive layer by at least the deformable layer, the distance between the electrode layer and the resistive layer at the pressure point being reducible in relationship to the amount of pressure applied at the pressure point, wherein the deformable layer defines a local capacitance between the electrode layer and the resistive layer at the pressure point and wherein the resistive layer defines corresponding resistances between the pressure point and the at least two pairs of mutually spaced electrodes,evaluating means, electrically connected to the at least two pairs of mutually spaced electrodes and to the electrode layer, for receiving electric signals from the at least two pairs of mutually spaced electrodes, the electric signals representing the local capacitance and the corresponding electric resistances,the evaluating means further comprising:

  • means for evaluating the local capacitance and the corresponding electric resistances and for outputting data indicating the amount of pressure at the pressure point and the position of the pressure point relative to the input surface,a filtering circuit connected to the electrode layer and to at least one electrode of the at least two pairs of mutually spaced electrodes, andmeans for generating an output signal upon application of an input voltage to the filtering circuit, the output signal indicating the amount of pressure at the pressure point and the position of the pressure point relative to at least two electrodes of the at least two pairs of mutually spaced electrodes.

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