| 摘要 |
PROBLEM TO BE SOLVED: To prevent a rotation signal error from being output being caused by a rattling object to be detected in a rotational direction. SOLUTION: When a code of a differential output s4 between outputs A and B of Hall elements 2a and 2b reverses, a holding circuit 6 takes an output C of a middle Hall element 2c. A level of the output C is different depending on a rotational direction of a gear (object to be detected) 1, and therefore an output prohibiting circuit 8 detects a change in rotational direction on the basis of the level of the output C held by the holding circuit 6. The output prohibiting circuit 8 shuts a power source of an output transistor 7 for an estimated time when detecting the change in rotational direction, thus prohibiting a rotational signal from being output. Only a normal rotation is output as a detect signal and a rotation resulting from rattling is prevented from being detected and output.
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