COUNTER AND A REVOLUTION STOP DETECTION APPARATUS USING THE COUNTER

摘要

A counting device having an excellent fail-safe function. According to a first invention, a counter (1) counts pulse signals (P1) to be counted and then counts the cycles of a high-frequency signal (P2). When the frequency of the high-frequency signal (P2) is a predetermined value, a frequency judging circuit (30) generates a judgement signal representing that the counter is normal. According to a second invention, a counter (100) is preset by a preset signal, the counter resetting is confirmed based on the output of a self-hold circuit (102), and another self-hold circuit (104) generates a count output. According to a third invention, such a counting device is used as a timer circuit (203, 300, 400) to determine the rate of generation of the revolution detection pulse signal (Ip) generated based on a sensor signal, thereby detecting the stop of revolution of a rotating body.