US Patent 7852228 Fan system and detector thereof

A fan system including a motor, a driving unit, and a detector is disclosed. The driving unit is electrically connected to the motor and generates a driving signal to drive the motor and a detection signal. The detector is electrically connected to an output terminal of the driving unit and receives a voltage signal and the detection signal. When the motor operates normally, the detector outputs an examined signal to the output terminal of the driving unit. When the motor operates abnormally, the driving unit asserts the detection signal, and the detector is controlled by the asserted detection signal to transform the examined signal to an alarm signal according to the voltage signal to detect the abnormal state.