Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
  • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
  • G01K7/003—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using pyroelectric elements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
  • G01J5/20—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
  • G01J5/22—Electrical features thereof
  • G01J5/24—Use of specially adapted circuits, e.g. bridge circuits

Definitions

• the present invention relates to a pyroelectric detector and to a method of improving the sensitivity of the pyroelectric material in the pyroelectric detector.
• a typical known pyroelectric detector is illustrated schematically in Figure 1, in which a temperature change in a pyroelectric material P will generate a voltage change on the gate of a junction field effect transistor J that can be measured at its output 2 with suitable circuitry.
• Line 3 is the supply voltage line to the transistor J and line 1 is at ground.
• a resistor R arranged in parallel with the pyroelectric material P has the dual function of controlling the electrical time constant of the device and of correctly biasing the gate of the transistor J.
• An objective of the present invention is to provide an improved pyroelectric detector to that illustrated in Figure 1.
• a method of improving the sensitivity of a pyroelectric material in a pyroelectric detector comprising applying a bias across the pyroelectric material to enhance the sensitivity of the pyroelectric material above that obtained when no bias is applied across the pyroelectric material.
• a pyroelectric detector comprising a circuit arrangement incorporating a pyroelectric material, the arrangement being such that when in operation the pyroelectric material is subjected to an applied bias potential, the output of the pyroelectric detector for a temperature change in the pyroelectric material being dependent upon the strength of the bias applied across the pyroelectric material.
• the pyroelectric material is electrically coupled to the gate of a junction field effect transistor whereby a temperature change in the pyroelectric material generates a voltage change at the gate of the junction field effect transistor.
• the junction field effect transistor can be omitted or replaced by an alternative component as for example a MOSFET, a bipolar transistor or a. resistor if a sufficiently high radiation level were being measured.
• a resistor is arranged in series with the pyroelectric material the resistor being provided between the pyroelectric material and a low or zero voltage line.
• Figure 1 is a schematic illustration of a known pyroelectric detector
• Figure 2 is a schematic illustration of a pyroelectric detector according to an embodiment of the present invention.
• FIG. 2 An improved radiation detector is shown in Figure 2.
• a non- signal side (lead 4) of the pyroelectric element P is taken to an external high voltage source (not shown) so that the pyroelectric material is operated under a bias field.
• the pyroelectric material used should be one having properties which are enhanced under these conditions and greater sensitivity is obtained.
• a detector structure may be fabricated, for example, in which the pyroelectric material P is a modified lead zirconate ceramic, J is a field effect transistor and R is 10 10 ohms.
• the device area can be approximately 1mm 2 and its thickness approximately 50 ⁇ m.
• the pyroelectric material element P may be only one of a multiplicity of similar elements arranged as a one or two dimensional array.
• the transistor J serves as a convenient impedance converter. It could be omitted or replaced by an alternative component eg. a MOSFET, a bipolar transistor or even a resistor if sufficiently high radiation level are to be measured.
• the resistor R may not be required or may be built into the material of P depending on the bias requirements of the transistor J.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=10644336

Family Applications (1)

Country Status (4)

Cited By (1)

Family Cites Families (2)

• 1988
  • 1988-09-28 GB GB8822693A patent/GB2223571B/en not_active Expired - Lifetime
• 1989
  • 1989-09-21 WO PCT/GB1989/001111 patent/WO1990003556A1/en not_active Application Discontinuation
  • 1989-09-21 EP EP89910879A patent/EP0419583A1/de not_active Withdrawn
  • 1989-09-21 JP JP1510010A patent/JPH03502735A/ja active Pending

Non-Patent Citations (1)

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