Patent ID: 8259955

Claim:
A fan noise canceling system, consisting of a loudspeaker, a sensor, and a digital signal microprocessor; the digital signal microprocessor including: a signal amplifying unit consisting of a pre-amplifier and a power amplifier; the pre-amplifier being electrically connected to the sensor and a fan, and the power amplifier being electrically connected to the loudspeaker; a signal converting unit consisting of an analog to digital converter (ADC) and a digital to analog converter (DAC); the ADC being electrically connected to the pre-amplifier, and the DAC being electrically connected to the power amplifier; and a hybrid controller being electrically connected to the ADC and the DAC; whereby when the fan operates and a feedforward signal is generated due to a speed change of the fan, and the sensor detects a feedback signal that feeds back an error, the feedforward signal and the feedback signal are sent to the pre-amplifier for signal amplification; the amplified signals are then sent to the ADC for converting into a digital signal; the hybrid controller receives and corrects the digital signals, and conducts rapid convergence algorithm to derive a reverse digital signal, which is then sent to the DAC for converting into a reverse analog signal; and the reverse analog signal is sent to the power amplifier for power amplification to generate a control signal, so that the loudspeaker is driven by the control signal to produce a reverse acoustic wave for canceling out noise produced by the fan to thereby achieve the purpose of canceling wide-frequency noise.