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Pen position and tilt estimators for a digitizer tablet

  • US 5,239,489 A
  • Filed: 05/06/1991
  • Issued: 08/24/1993
  • Est. Priority Date: 05/06/1991
  • Status: Expired due to Fees
First Claim
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1. A digitizer tablet comprising a fixed array of inductors for use with an external moveable inductor and including means for determining a magnitude of a mutual inductance between the array of inductors and the moveable inductor, the digitizer tablet further including means, coupled to an output of the determining means and responsive to the determined magnitude, for deriving an estimate of the position of the moveable inductor relative to a coordinate system associated with the fixed array of inductors, wherein the determining means includes measurement means for measuring a magnitude of an induced electrical signal from individual ones of the fixed array of inductors, and wherein the estimating means includes means for weighting a plurality of the measurements in accordance with a first weighting function for determining an estimated position of the moveable inductor in accordance with a least squares line fit of the plurality of weighted measurements.

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