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Ultrasonic length measuring apparatus and method for coordinate input

  • US 20030144814A1
  • Filed: 01/30/2003
  • Published: 07/31/2003
  • Est. Priority Date: 01/31/2002
  • Status: Active Grant
First Claim
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1. An ultrasonic length measuring apparatus comprising:

  • a transmission unit for transmitting an ultrasonic wave;

    at least one receiving unit for receiving an ultrasonic wave and converting it into an electric signal;

    a timing detection unit for measuring the number of times of the crossing of the waveform of the received ultrasonic wave signal from the receiving unit over a predetermined threshold value and for detecting a crossing timing after predetermined times from a crossing point of a first crossing;

    a time measuring unit for measuring the time period from the start of transmission of the ultrasonic wave by the transmission unit to the crossing timing detected; and

    a length measuring unit for calculating a length based on the time measured.

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