Importance

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Abstract

A counting apparatus having excellent fail-safe characteristics can be used in a rotation-stopped detection apparatus. As a first feature, timing of a high-frequency signal P.sub.2 is carried out by a counter 1 after completion of a counting of pulse signals P.sub.1. When the frequency of the timing output for the high-frequency signal is a predetermined value, a judgment signal, indicating that the counting is normal, is generated by a frequency discriminating circuit 30. As a second feature, a counter 100 is preset using a preset signal. Then, after verifying by an output from a self hold circuit 102 that the counter 100 has been reset, a counting output is generated from a self hold circuit 104. As a third feature, the counting apparatus is used as timer circuits 203, 300, 400, and the generation frequency of a rotation detection pulse signal I.sub.P based on a sensor signal, is obtained to thereby detect a rotation-stopped condition of a rotating body.

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First Claim