| 摘要 |
PURPOSE:To reduce the size of a battery by applying a strobe pulse to judge the motor load from the induced voltage waveform, thereby largely reducing the output times of an additional pulse. CONSTITUTION:A strobe pulse forming circuit 71 for outputting strobe pulse group formed of pulse groups of two phases displaced by half period from each other for several milliseconds several tens milliseconds immediately after a motor drive pulse, and a motor driver 80 in which two output terminals alternately become high impedance state by the strobe pulse group are provided. The polarity of the induced electromotive force is discriminated by an induced voltage patterning circuit 72, and patterned, compared with a reference pattern by a pattern discriminator 73, and the output signals of the circuits 72, 73 are inputted to a control signal forming circuit 74. Then, signals UP, DN, HRY for controlling the pulse width of a motor drive pulse Pm and a chopper ratio are formed by the circuit 74. |
