| 摘要 |
PURPOSE:To enable analog outputting from the level 0 whenever an object to be measured enters an irradiation area, by turning a signal based on the results of comparison of signals forcibly to 0 when they are below the threshold while the signal is outputted as intact when they are above the threshold. CONSTITUTION:A peak holding circuit 40 introduces an output signal of a low-pass filter 22 thereinto and outputs the peak value thereof to a control pulse generator 41 at the next stage. The pulse generator 41 having the threshold Vs outputs a reset signal Sr and an inhibit signal Six to control a U/D counter 26. In other words, while the voltage Vp from the circuit 40 is smaller than the threshold Vs, the output of the U/D counter 26 turns to 00... with the inhibit signal Six ON and the output of an amplifier U2 turns to 0 as the output of an amplifier U1 is goes to 0. Then, when an object enters a laser light irradiation area, the signal S1 from an image sensor section gives a large amplitude making the output signal Vp of the circuit 40 exceed the threshold Vs. The pulse generator 41 detects this condition to turn OFF the inhibit signal Six. |
