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Dual mode digitizer tablet system

  • US 6,180,894 B1
  • Filed: 05/07/1998
  • Issued: 01/30/2001
  • Est. Priority Date: 05/07/1998
  • Status: Expired due to Fees
First Claim
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1. A digitizer tablet system comprising:

  • a tablet and a first cordless pointing device, said first cordless pointing device generating an electromagnetic wave;

    a detection loop sensing circuit for detecting an electromagnetic wave;

    a signal processing circuit for processing the detected electromagnetic wave and generating a filtered signal;

    a signal shaping circuit for shaping said filtered signal into a square wave signal;

    a frequency divider for dividing the frequency of said square wave signal and generating a lower frequency square wave signal;

    a micro-controller having an analog to digital converter;

    a frequency counter for counting the frequency of said lower frequency square wave and sending the frequency count to said micro-controller; and

    a half-wave rectifier for rectifying said filtered signal and sending a rectified signal to said analog to digital converter, said rectified signal being digitized and said micro-controller determining the location of said pointing device by processing said digitized signal.

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