Patent ID: 7773760

Claim:
An active vibration noise control apparatus comprising: a control sound source for generating control sound in a space in which noise is transmitted from a noise source; frequency detecting means for detecting a noise generating state of said noise source and outputting a harmonic base frequency selected from frequencies of the noise generated by the noise source and a base period corresponding to said base frequency; residual noise detecting means for detecting residual noise at a predetermined position in said space; and active control means for driving said control sound source to reduce the noise in said space based on a base signal and said residual noise; said active control means comprising: a waveform data table for storing waveform data of a sine wave or a cosine wave discretized into a predetermined number of values; sampling period calculating means for calculating a sampling period based on said base period; and base signal generating means for reading the waveform data from said waveform data table and generating said base signal; wherein said sampling period calculating means: uses the base period of a particular base signal in a control range as an upper limit base period, and determines a division number which is a value produced when said upper limit base period is divided by an upper limit sampling period which is necessary for said active control means to provide a noise canceling capability; uses a period produced when a lower limit sampling period which is a limit of a processing capability of said active control means is multiplied by said division number, as an identical division number lower limit base period; and if the base period of said base signal is present in a range between said upper limit base period and said identical division number lower limit base period, outputs a value produced when the base period of the base signal is divided by said division number as said sampling period; and wherein said base signal generating means: uses the quotient produced when said predetermined number is divided by said division number or the sum of said quotient and 1 as a step number, and reads the waveform data from said waveform data table for each said step number in a sampling period which is of a value produced when said base period of said base signal is divided by said division number, thereby to generate said base signal.