Patent ID: 7536018

Claim:
An active noise cancellation system, comprising: a base signal generator that generates a base signal composed of a harmonic having a frequency selected from a frequency of vibration or noise produced from a vibration or noise source; an adaptive filter that outputs a control signal based on the base signal; a first canceling signal emitter that emits a canceling signal for canceling out the vibration or noise generated based on the control signal; an error signal detector that detects a residual vibration or noise at an evaluation point due to interference between the emitted canceling signal and the produced vibration or noise, as an error signal; a correction filter that corrects the base signal, by a correction value indicating a transfer characteristic of the produced vibration or noise that corresponds to the harmonic frequency of the base signal from the first canceling signal emitter to the error signal detector, to generate a reference signal; a filter coefficient updater that successively updates a filter coefficient of the adaptive filter based on the error signal and the reference signal such that the error signal is minimized; a compensation filter that corrects the control signal by a prescribed value; and a second canceling signal emitter that emits the canceling signal generated based on the corrected control signal; wherein the correction value of the correction filter is set to a sum obtained by adding the transfer characteristic from the first canceling signal emitter to the error signal detector, and a product obtained by multiplying the transfer characteristic from the second canceling signal emitter to the error signal detector by the prescribed value.