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Composite fire sensor

  • US 4,640,628 A
  • Filed: 07/11/1985
  • Issued: 02/03/1987
  • Est. Priority Date: 07/11/1984
  • Status: Expired due to Fees
First Claim
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1. A composite fire sensor comprising a first sensor element sensitive to a change in incident infrared rays, a second sensor element having a variable electric conductivity according to gas absorption/desorption, said first sensor element being sensitive to heat and flame, said second sensor element being sensitive to smoke and gas and both producing outputs, at least one comparator means for combining the outputs of said first and second sensor elements, said at least one comparator means adapted to change its sensitivity to produce an alarm output in response to said outputs of said first and second sensor elements, and a delay circuit for delaying said alarn output of said at least one comparator means, wherein predetermined reference voltages along with the output of the first and second sensor elements are fed to said comparator means to produce said alarm output.

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