PYROELECTRIC INFRARED SENSOR AND SYSTEM THEREOF

摘要

PURPOSE:To obtain an output which does not depend upon the temperature difference of a chopper. CONSTITUTION:A three-blade chopper is chopped. Since a temperature difference occurs among the three choppers at the time of stopping in the state before a measuring space sensing, an abnormal sensor output (b) is, because the third chopper becomes higher temperature than those of the other two choppers, obtained. The signal of the state that the chopper is closed is the temperature of the chopper itself. Then, the sensor signal (c) when a heat generating object of a predetermined temperature for sensing a measuring space indicate an abnormal value at each three since the temperature of the third chopper is different from those of the other two choppers. Therefore, the temperature of the chopper immediately before the measuring space sensing is fed back to the sensor output during the space sensing thereby to obtain an accurate sensor measurement output signal (d) which has no unevenness and no error without depending upon the temperature difference among the choppers and the temperature of the chopper.