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Light-emitting device having a phosphor particle layer with specific thickness

  • US 7,176,647 B2
  • Filed: 03/11/2003
  • Issued: 02/13/2007
  • Est. Priority Date: 03/11/2003
  • Status: Expired due to Fees
First Claim
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1. A barrier movement control apparatus, the apparatus comprising:

  • an ultrasonic measurement device positioned on the movement control apparatus to measure a length of a barrier;

    an analysis unit in communicative connection with the ultrasonic measurement device to determine the length of the barrier and to generate a state signal based on length information obtained from said ultrasonic measurement unit; and

    a barrier control unit responsive to a state signal from said analysis unit to control the barrier operational characteristics based on said state signal.

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