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Humidity and temperature responsive switch

  • US 3,936,793 A
  • Filed: 11/11/1974
  • Issued: 02/03/1976
  • Est. Priority Date: 11/11/1974
  • Status: Expired due to Term
First Claim
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1. A temperature and humidity responsive switch comprising:

  • a base member;

    an elongated stationary member with one end attached to said base member and a second end supporting a contact;

    an elongated bendable switch element having one end attached to said base member and a movable second end supporting a contact in alignment with the contact on said stationary member so as to cause engagement of said contacts when the second end of the switch element moves toward said stationary member during bending of the switch element;

    said switch element having a laminated structure with a metal portion and a plastic portion bonded together in a manner so that differences in their respective coefficients of thermal expansion affect the position of the movable second end of said switch element with respect to said second end of the stationary member;

    said elongated switch element being separated by slot means into side by side strip portions whose end portions adjacent said movable second end are joined and whose mid-portions are movable in the lateral direction with respect to one another;

    at least one of said strip portions being shortened in length, thereby causing the middle of the remaining strip portion to bend laterally in one direction from the general plane of the switch element during a low range of ambient temperatures and to cause the contact on the movable second end of the switch element to be positioned away from the contact on said second end of said stationary member and subsequently causing the middle portion to pass through the plane of the switch element and to bend in an opposite lateral direction with increasing ambient temperatures due to the differences in thermal coefficients of the metal and plastic so as to cause the contact on the second end of the switch element to engage the contact on the stationary member in a rapid and positive manner.

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