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Security systems

  • US 4,196,347 A
  • Filed: 07/10/1978
  • Issued: 04/01/1980
  • Est. Priority Date: 07/10/1978
  • Status: Expired due to Term
First Claim
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1. A security system comprising:

  • light-source means;

    key means for responding to light emitted by said light-source means, said key means including oscillator means adapted to be powered electrically to emit electromagnetic radiation, means for converting light energy received from said light-source means to electrical energy, and means for supplying said electrical energy to power said oscillator means to emit said electromagnetic radiation; and

    receiver means for receiving electromagnetic radiation emitted by said oscillator means, said receiver means including means responsive to the said received electromagnetic radiation to provide manifestation thereof.

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