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Carbon monoxide and smoke detection apparatus

  • US 6,426,703 B1
  • Filed: 04/09/1998
  • Issued: 07/30/2002
  • Est. Priority Date: 08/07/1997
  • Status: Expired due to Term
First Claim
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1. An apparatus to detect a condition in the environment comprising:

  • a sensing device having a light emitting source to direct light at a sensor and a light receiving device to detect the light passing through the sensor, the sensor changing color upon exposure to carbon monoxide;

    a smoke detector having a first electrode disposed between second and third electrodes;

    a comparator having a first terminal, a second terminal, and an output terminal, the first terminal electrically coupled to the first electrode and the second terminal being maintained at a reference voltage, the comparator producing a detection signal upon the voltage at the first terminal exceeding the reference voltage applied at the second terminal;

    control circuitry selectively activating the light emitting source to cause the voltage of the light receiving device to increase, the control circuitry determining the amount of time for the voltage of the light receiving device to reach a predetermined voltage level, the control circuitry computing a rate of change between a plurality of times for the light receiving device to reach the predetermined voltage level, the control circuitry also being responsive to the detection signal from the comparator wherein the control circuitry includes executable instructions to automatically and periodically test the operation of the sensing device and the smoke detector;

    an alarm energizable to reproduce a first prestored audible horn output pattern when the rate of change between the plurality of times reaches a predetermined value;

    to reproduce a second prestored audible horn output pattern when the first electrode reaches a preset voltage level; and

    an elongated multi-function, test initiating member movable from a first to a second position wherein in response to the member being moved to the second position, the control circuitry enters a test mode and generates audible and visible indicia thereof.

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