| 摘要 |
PROBLEM TO BE SOLVED: To realize highly reliable control with no stepping of a pointer by supplying first and second field detection pulses having different polarity to a drive coil prior to a drive pulse thereby eliminating the effect of an external field and the field from a power generating unit. SOLUTION: At step ST 21, a decision is made whether an auxiliary pulse has been outputted during the preceding cycle. If the auxiliary pulse has been outputted, a demagnetization pulse is outputted immediately at step ST 25 followed by output of a drive pulse at step ST 26. The demagnetization pulse has a polarity reverse to that of the auxiliary pulse and the effective power of drive pulse can be increased by supplying a next cycle drive pulse following to the demagnetization pulse. Since a rotor can be turned surely even when power generation is sustained and a field is present or when a residual field is present, detection of rotation is omitted and the possibility of erroneous detection is eliminated resulting in reliable stepping of a pointer. |
