| 摘要 |
PROBLEM TO BE SOLVED: To appropriately detect induced voltage of field winding of a step motor by lengthening the update time of an AC signal applying to the step motor for causing an indication action to the pointer in the detection of a zero-returning position of a pointer in an indicating instrument of a vehicle for using the step motor as a driving source. SOLUTION: A phase and B phase driving voltage is applied to the step motor in two times longer update time t2 (correspond to pulse width W1) than the update time t1 corresponding to pulse width W1 in usual driving. Therefore, since the induced voltage producing in field winding of the step motor sufficiently builds up in the update time t2, a step 130 is judged with the induced voltage, and adjustment of the zero-returning position and stop of applying the driving voltage are conducted in the engaging of the pointer with a stopper. |
