| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a device for detecting the number of revolutions for detecting the number of revolutions of a rotator, capable of determining the presence of abnormal conditions of a filter circuit allowing a revolution pulse signal to pass therethrough in accordance with the revolution angle of the rotator. <P>SOLUTION: A revolution pulse signal (voltage V1 of a connection point 26) is compared with a threshold Vth by using a counter 23 counting the revolution pulse signal. A first time V1_H and a second time V1_L in which the revolution pulse signal does and does not exceed the threshold Vth, respectively, are thereby obtained. Further, it is determined whether the ratio of the first time V1_H to the second time V1_L is within a specific range by using a decision unit 24. Accordingly, the presence of abnormal conditions of one or both of a first filter circuit 15 and a second filter circuit 22 is determined. <P>COPYRIGHT: (C)2011,JPO&INPIT |
