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Pyroelectric infrared detector

  • US 5,468,960 A
  • Filed: 05/10/1994
  • Issued: 11/21/1995
  • Est. Priority Date: 05/12/1993
  • Status: Expired due to Fees
First Claim
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1. A pyroelectric infrared detector used in an intrusion detection system, the detector comprising:

  • a housing having an opening;

    a light transmissive filter covering the opening in the housing;

    a group of at least two infrared transmissive pyroelectric layers, each layer having a top surface and a bottom surface, the top surface of each layer facing the opening, and each layer in the group of layers disposed in layered relation with respect to each other layer;

    a substrate layer electrically connected to each pyroelectric layer in the group of layers, the substrate layer located such that the group of layers is between the substrate layer and the opening, the substrate layer comprising an electric circuit including a field-effect transistor for converting an impedance;

    a plurality of electrodes, at least one electrode formed on each of the top and bottom surfaces of each of the pyroelectric layers for transmitting electric charges occurring on each of the top surfaces caused by thermal changes due to infrared incidence on each top surface; and

    means for supporting the group of pyroelectric layers and the substrate layer at spaced intervals so that the substrate layer and the group of pyroelectric layers are free from mutual thermal influence.

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