ApplicationNo. 06/137028 filed on 04/03/1980
US Classes:250/338.3Pyroelectric type
ExaminersPrimary: Smith, Alfred E.
Assistant: Fields, Carolyn E.
Attorney, Agent or Firm
International ClassesG01J 5/10 (20060101)
G01J 5/34 (20060101)
G08B 13/191 (20060101)
H01L 37/02 (20060101)
H01L 37/00 (20060101)
G08B 13/189 (20060101)
Foreign Application Priority Data1979-04-12 GB
AbstractIn a pyroelectric detector circuit arrangement in which a pair of capacitive detector elements (C1 and C2) formed of polarized pyroelectric material are electrically connected in series with the directions of polarization of the elements being such that the normally produced signal voltages are in opposition, means are provided for inhibiting the depoling of the elements under conditions of cooling or excessive temperature cycling. These depoling inhibiting means comprise a pair of ultra-low leakage diode elements (D1 and D2) in series opposition connection and arranged in parallel connection with the capacitive detector elements. Connections are present between the common points in the diode series and the capacitive detector element series. The diode elements are arranged with respect to the directions of polarization of the detector elements so that under conditions of large decreases in temperature of the detector elements the voltages generated across the detector elements are effective to forward bias the diode elements into conduction and thereby inhibit depoling of the detector elements. The diode elements, under normal conditions of irradiation of the detector elements, present a high impedance path between the input of FET amplifier means and a point of constant potential.In one embodiment the capacitive detectors (C1 and C2), the ultra-low leakage diode elements (D1 and D2), and FET amplifier means are present in a common envelope in the form of a hybrid microcircuit having only three external terminal connections.