| 摘要 |
PURPOSE:To eliminate the vibrating noise of a pulse motor by selecting one of two types of pulses exceeding audible frequency in response to the level of a current flowing through a circuit and applying it as a switching pulse, thereby maintaining the effective current value flowing through the circuit constant. CONSTITUTION:An oscillator 11 generates two types of pulses (a), (b) of duty ratio exceeding the audible frequency. The pulses (a), (b) are selected by a selector 12, and are outputted as a switching pulse (d). The current flowing through a circuit is smoothed and detected by an integration circuit 13, the output of the integration circuit 13 is applied to level detectors 14, 15, which compares the output with the set value. The selector 12 is controlled by the output signals of the detectors 14, 15 to select any of the pulses (a), (b). The duty ratio of the pulses (a), (b) is alternately selected by the selector 12 for the pulses (a), (b), thereby maintaining the effective current value flowing through the circuit constant. |
