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Cordless digitizer stylus status encoding and transmission scheme

  • US 5,247,138 A
  • Filed: 11/08/1991
  • Issued: 09/21/1993
  • Est. Priority Date: 11/08/1991
  • Status: Expired due to Fees
First Claim
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1. In a cordless digitizing system wherein a cordless stylus transmits positional pulses to a tablet at a carrier frequency, a method for transmitting status information about the stylus to the tablet comprising the steps of:

  • a) assigning a first unique and recognizable sequence of carrier frequency cycles to be a first binary state wherein said first sequence comprises a number of cycles of carrier signal, a contiguous portion of a predetermined length of said first sequence being suppressed;

    b) assigning a second unique and recognizable sequence of second binary state wherein said second sequence comprises said number of cycles of carrier signal, said second sequence being generally unsuppressed; and

    ,c) transmitting the status information in binary form employing said first unique and recognizable sequence of carrier frequency cycles as said first binary state and said second unique and recognizable sequence of carrier frequency cycles as said second binary state, and wherein said first and second sequences are transmitted in continuous succession whereby successive sequences of said second binary state comprise contiguous unsuppressed cycles of carrier signal.

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