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Heat detector including device for detecting abnormality of external temperature sensor

  • US 5,448,224 A
  • Filed: 03/25/1994
  • Issued: 09/05/1995
  • Est. Priority Date: 03/31/1993
  • Status: Expired due to Term
First Claim
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1. A heat detector comprising:

  • a casing;

    an external temperature detector located outside said casing for detecting an external temperature outside said casing;

    an internal temperature detector located within said casing for detecting an internal temperature inside said casing;

    processing means, operatively coupled to said external and internal temperature detectors, for calculating a temperature difference between the external temperature detected by said external temperature detector and the internal temperature detected by said internal temperature detector, for detecting when the thus calculated temperature difference has remained greater than a predetermined value for at least a predetermined duration, and for outputting an abnormality signal indicating that said external temperature detector is abnormal upon detecting that the calculated temperature difference has remained greater than the predetermined value for at least the predetermined duration.

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