| 摘要 |
PURPOSE:To detect an object even when the time of an open signal is very short by outputting a signal representing the object detecting state when an interruption signal obtained from a photodetection section of an optical modulation type photo interrupter is inputted consecutively for n-time and returning an output signal into the non-detection state when the open signal is inputted from the photodetection section. CONSTITUTION:When two objects are accessed to a degree of in contact with each other as shown in periods b, c, Q outputs of D flip-flop circuits 1-3 all go to a high level at a point of time when a low level of 3-pulse is inputted from a time t3 as to the object shown in the period (b). Thus, an output of a NAND circuit 5 goes to a low level and an output of a latch circuit 8 goes to a high level to obtain a detection output (f) corresponding to the period (b). Furthermore, the period of the clock pulse is set to a time equal to the minimum time or a gas when two objects pass continuously or shorter than that thereby causing a clock pulse without fail in a period (e). Thus, even when the time of the open signal generated between the objects is very short, mis- detection of the object is not caused. |
