| 摘要 |
PURPOSE:To reduce the size of a battery by applying a strobe pulse and judging the load of a motor from the waveform of the induced voltage, thereby largely reducing the number of additional pulse outputs. CONSTITUTION:A strobe pulse forming circuit 71 which outputs a strobe pulse group formed of 2-phase half-period-displaced pulse group for several milli- seconds to several tens milli-seconds immediately after the motor drive pulse, a motor drive circuit 80 in which two output terminals alternately become high impedance state by the strobe pulse group are provided, the positive or negative of the polarity of the induced voltage is discriminated, patterned by a patterning circuit 72, and the continuing time of the positive or negative range of the induced voltage is measured. A pattern discriminator 73 divides the magnitudes of the motor load into three levels by the induced voltage pattern, and the pulse width of the motor drive pulse or the chopper ratio is controlled with the reference level set at the intermediate as a target pattern. |
