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Infrared audio transmitter system

  • US 5,548,654 A
  • Filed: 04/07/1994
  • Issued: 08/20/1996
  • Est. Priority Date: 04/07/1994
  • Status: Expired due to Term
First Claim
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1. An assistive listening system for transmitting audio sound waves over an infrared signal, said system comprising:

  • means for converting said audio sound waves to an audio electrical signal, said audio electrical signal including upper and lower frequency signals;

    oscillator means for generating a base carrier electrical signal;

    means for modulating said base carrier electrical signal with said audio electrical signal so as to generate a modulated electrical signal, said modulated electrical signal having an associated duty cycle;

    emitter means for converting said modulated electrical signal into a corresponding infrared light signal, said emitter means having an associated power dissipation varying with the duty cycle of said modulated electrical signal; and

    means for adjusting the duty cycle of said modulated electrical signal so as to adjust the current through said emitter means and thereby limit the power dissipation of said emitter means.

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