Patent ID: 6549136
Filing Date: 2003-04-15
Classification: G01F,G01M,G01N

Abstract:
A sensing and switching circuit comprising:(a) a body of positive-temperature-coefficient material having a first conductive coating on a first surface thereof and a second conductive coating on a second surface thereof, said second conductive coating being divided into a first zone and a second zone which are not in direct electrical contact with each other, (b) a source of first electric potential connectable to said first conductive coating, (c) first resistive means for connecting said first zone of said second conductive coating to a source of second electric potential different from said first electric potential, said first resistive means having first and second terminals and a node intermediate said first and second terminals, (d) second resistive means for connecting said second zone of said second conductive coating to a source of electric potential different from said first electric potential, (e) first switching means for connecting said source of first electric potential to said first conductive coating, (f) means for thermally coupling said first zone of said second conductive coating, and the portion of said body of positive-temperature-coefficient material proximate thereto, to a heat receptor, and (g) output switching means coupled to said node.