| 摘要 |
PURPOSE:To fluctuate the flow rate of wind of the fan of a vehicle with a fluctuation width corresponding to a wind flow rate set by the driver of the vehicle, by providing a fluctuating circuit, a triagnular wave generation circuit and a drive circuit. CONSTITUTION:A fan controller comprises a fluctuating circuitIwhich generates a fluctuating signal, a pulse width modulation circuit II consisting of a triangluar wave generation circuit TC which produces a triangular wave signal of constant amplitude and period and a comparator circuit C connected to the circuitsI, TC, and a drive circuit III including a switching power transistor PT. The transistor PT is controlled to be on and off, by the duty factor of a pulse signal modulated by a pulse width determined by the fluctuating signal and the triangular wave signal, so that the rotational frequency of a motor M corresponds to the duty factor of the pulse signal. This results in fluctuating the flow rate of wind of a fan.
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