PYROELECTRIC INFRARED DETECTOR HAVING FREQUENCY TRANSFER FUNCTION AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a pyroelectric infrared detecting unit having a high response in a low frequency area. SOLUTION: A rectangular open window is provided in an upper surface of a main body case 1 made of metal, and an infrared ray filter 2 is fitted in this open window. The pyroelectric signal to be generated by the absorption of the infrared ray by a pyroelectric element 3 is transmitted to a support 4 made of the chrome plated material. Radiation of heat of the pyroelectric element 3 and dispersion of heat thereof due to the convection is prevented by the heat insulating material 12, which is coated on the inner wall surface of the main body case 1 and which is made of the synthetic resin. Since the material for the support 4 is changed from the conventional silver plated material to the chrome plated material at a low heat conductivity, dispersion of heat of the pyroelectric element 3 due to the heat conduction is lowered. Cut-off frequency of the pyroelectric infrared ray detecting unit can be deviated to a low frequency side, and the low frequency response of the pyroelectric infrared ray detecting unit is improved so as to enable the detection of an object, which moves at a low speed.