| 摘要 |
PURPOSE:To effectively prevent the occurrence of abnormal sound during operation without installing interphase capacitors. CONSTITUTION:A comparator 52 is provided, and this judges whether a voltage corresponding to an input signal from a vehicle speed sensor 46, which changes with the vehicle speed, is higher or lower as compared with a predetermined voltage VA and outputs different signals (with setting voltage VA) according to respective conditions. Also provided is a first drive means for driving a pulse motor by stages by increasing an excitation current to respective phase coils 1A to 1D of the pulse motor stepwise by means of signals from the comparator 52 which are outputted in response to a low voltage. Moreover, a second drive means is provided, which drives the pulse motor in one stage by the signals from the comparator 52 which are outputted in response to a high voltage. |
