| 摘要 |
PURPOSE:To detect the time of a moving body with substantial accuracy by determining the peak timing of the differential signal of the signal detected in the positions differing along the passage direction of the moving body when said body passes through a prescribed position. CONSTITUTION:The forward end of the image of a mark M for printing paper arrives at the photodetection part Pa of a photoelectric detector 10A, then said end arrives at the photodetection part Pb of a photoelectric detector 10B at a time t2; thereafter, the rear end passes through said parts respectively at t3 and t4. The respective detection signals are inputted with amplifiers 20A, 20B to a differential signal detection circuit 30, from which a differential signal C is inputted to a differentiation circuit 40 and a gate signal generation circuit 50. The differentiation signal from the circuit 40 is inputted to a zero cross detection circuit 60. The zero cross signal therefrom is inputted through a gate circuit 70 operated by the gate signal from the circuit 50 to a pulse shaping circuit 80, which outputs a time detection signal T. The time is thus detected with substantial accuracy. |
