| 摘要 |
PURPOSE:To provide a control circuit of only a speed control loop and prevent an operation point from fluctuating due to the ambient temperature change or secure change, by comparing the outputs of a time difference pulse generation circuit and a reference time width generation circuit with each other by a pulse synthesis circuit. CONSTITUTION:The revolution speed of a motor 1 is detected by two detectors 13A, 13B to produce signals of different phases. The width of time difference between the signals is detected by a time difference pulse generation circuit 4. A reference frequency generation circuit 2 supplies clock pulses to a reference time width generation circuit 3. Both the outputs of the circuits 4, 3 are synthesized with each other by a pulse synthesis circuit 5, the output of which has three states of current outflow, current inflow and a high impedance and is applied to the motor 1. This results in providing a speed control system in which the time difference width becomes equal to a reference time width. The same load characteristic as in the case of phase control through only one speed control loop can be provided. |
