Matsushita Electric Works, Ltd.

Toshio Fujimura

Yuji Takada

Teruki Hatatani

Shinji Sakamoto

A pyroelectric infrared ray sensor is constituted with a current-voltage converting circuit utilizing an impedance of feedback capacity, obtained by adding the feedback capacity to an operational amplifier receiving as an input an element current from a pyroelectric element, whereby the current-voltage converting circuit can be improved in S/N ratio without altering characteristics of the pyroelectric element.

Pyroelectric infrared ray sensor

A pyroelectric infrared ray sensor includes a voltage amplifying circuit provided with a signal amplifying part having a non-inverting amplifier, with an integrating circuit, and with voltage dividing resistors connected at a position where an input V.sub.IN to the voltage amplifying circuit and an output V.sub.B of the integrating circuit are resistance-divided to a non-inverting input terminal of the signal amplifying part which is practically formed by an operating amplifier, wherein the signal amplifying part includes a low-pass filter formed by a resistor and a capacitor, whereby the electrostatic capacity of the required capacitor can be minimized, and the entire circuit can be minimized in size and also in manufacturing costs.

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Kadoma, Japan

Toshio Fujimura