| 摘要 |
PURPOSE:To improve measuring precision by adding an infrared ray detected output to an operation amplifier through a parallel circuit having a different time constant and providing a mono-directional diode and a feedback compression circuit in parallel at said amplifier. CONSTITUTION:An infrared ray output emitted from a human body is selectively fetched by means of a detector 4 to obtain only an output according to an incident infrared ray. Two time constant circuits, one tau1 consisting of C1, R1 and the other tau2 consisting of C2, R2, are provided at input circuit 5. These circuits erase a signal overshoot so that an erroneous action may be eliminated. In addition, at the operation amplifier 6, a mono-directional diode D1 and Zener diodes D2, D3 are provided in parallel with the feedback circuit 7. The D1 removes a reverse signal at the amplification stage, while the D2, D3 gradually compress a positive major signal and eliminates a ringing output to improve a count precision. Further, at a pulse generating circuit, a pulse generating circuit 11 which applies inhibit action is provided to remove a double count. Thus, it is possible to prevent a miscount and a double count so as to enhance a measuring precision. |
