An active noise control apparatus (100) includes a first active noise controller (11) for generating a first canceling signal (Sc1) for a first noise type, a second active noise controller (12) for generating a second canceling signal (Sc2) for a second noise type that is different from the first noise type, a mixer (20) for mixing the first canceling signal (Sc1) and the second canceling signal (Sc2) into a mixed canceling signal (Sc0), a canceling sound output unit (28) for outputting a canceling sound based on the mixed canceling signal (Sc0), and an amplitude suppressor (50) for suppressing the amplitude of the second canceling signal (Sc2) depending on the amplitude of the first canceling signal (Sc1).

Active noise control apparatus

A cosine wave over one period is stored as waveform data in a memory, and address shift values based on a phase lag in transfer characteristics from a speaker to a microphone are stored in a memory An address shift value is read from the memory by referring to the frequency, and waveform data are read from the memory at addresses that are produced by shifting the addresses from which the reference cosine wave signal and the reference sine wave signal are read, by the address shift value The read waveform data are used as a first reference signal and a second reference signal, which are applied to adaptive notch filters, to suppress vibratory noise

Active vibratory noise control apparatus

The disclosed active vibration noise control device is suitable for use in cancelling out vibration noise by outputting control noise from a plurality of speakers. When a vibration noise frequency is in a dip bandwidth, the active vibration noise control device alters the step size parameters used to update the filter coefficient at at least one filter coefficient update means from among a plurality of filter coefficient update means. Thus, the filter coefficient update speed can be retarded in unstable dip bandwidths, enabling loss in silencing effect which occurs during dip characteristics to be appropriately reduced.

Active vibration noise control device

An active noise control device detects composite vibration of a vibration transmitting route to which both vibration of a rotating body caused by generation or transmission of drive force of a vehicle and vibration of a wheel generated by contact between the wheel and a road surface are transmitted. A first reference signal for defining a reference waveform of a canceling sound for canceling vibration noise in a vehicle interior is generated based on the composite vibration. The component of the canceling sound for canceling vibration noise of the rotating body is removed from the first reference signal to generate a second reference signal for defining a reference waveform of the canceling sound for canceling vibration noise of the wheel. The canceling sound is outputted based on the second reference signal.

Active noise control device

An active noise control system generates an anti-noise signal to drive a first speaker group including at least one speaker to produce sound waves to destructively interfere with an undesired sound in at least one quiet zone The active noise control system receives error signals representative of a combination of undesired sound and destructively interfering sound waves produced by the first speaker group The active noise control system may select a second speaker group to replace the first speaker group based on the error signals

System for active noise control with adaptive speaker selection

PROBLEM TO BE SOLVED: To provide an active type vibration noise controller in which computational quantity required to obtain reference signals is reduced and which provides sufficient vibration noise control effect. SOLUTION: In the active type vibration noise controller, the filter coefficients of an adaptive notch filter 14 are successively updated so that error signals outputted by a microphone 18 are minimized based on the error signals and first reference signals, wherein the first reference signals are obtained by subtracting signals that are obtained by multiplying a sine correction value C1 based on the sine value of phase characteristics by reference sine wave signals of vibration noise frequencies from signals that are obtained by multiplying a cosine correction value C0 based on the cosine value of the phase characteristics in signal transmission characteristics from a loudspeaker 17 generating canceling vibration noise to the microphone 18 by reference cosine wave signals of vibration noise frequencies. Moreover, filter coefficients of an adaptive notch filter 15 are successively updated so that error signals are minimized based on the error signals and second reference signals, wherein the second reference signals are obtained by adding signals that are obtained by multiplying the reference sine wave signals by the cosine correction value C1 to signals that are obtained by multiplying the reference cosine wave signals by the sine correction value C0. COPYRIGHT: (C)2005,JPO&NCIPI

Active type vibration noise controller

PROBLEM TO BE SOLVED: To provide an active type noise reducing device in which stable operations are obtained even though acoustic transmission characteristics are fluctuated by the change with time and external noise is mixed much and an ideal noise reducing effect is provided by suppressing excessive compensation at the ear positions of a crew. SOLUTION: The active type noise reducing device cancels noise by radiated sound from a speaker 23 which is driven based on the output of an adaptive notch filter 4. It is constituted so that updating of filter coefficients of the adaptive notch filter 4 is conducted by simulated cosine wave signals r0 and simulated sine wave signals r1 which are output signals from adders 13 and 14, error signals e which are output signals from a microphone 24 and correction signals h from an adder 33 that are the output signals of the filter 4 being acoustically transmitted to the microphone 24 employing initial transmission characteristics. COPYRIGHT: (C)2005,JPO&NCIPI

Active type noise reducing device

PROBLEM TO BE SOLVED: To provide an active vibration noise control unit that can prevent a unpleasant noise from being generated when a cancel signal is cut off and obtain a sufficient cancel signal, and can be constituted with an inexpensive microcomputer and has rapid response. SOLUTION: An adaptive filter 2 generates the cancel signal according to a reference signal of frequency based upon a vibration noise frequency and a speaker 3 is driven with the cancel signal to generate a cancel sound; and an error signal based upon the difference between vibration noise in a cabin and the cancel sound is detected to generate a reference signal based upon the error signal and a 1st filter coefficient arithmetic circuit 6 finds a 1st filter coefficient according to the reference signal and error signal so that the error signal becomes minimum. According to a switching indication from a switching circuit 11, the 1st filter coefficient right before the switching indication is multiplied by a specified value which is smaller than 1 to obtain a 2nd filter coefficient, and the 1st filter coefficient or 2nd filter coefficient is selected as a filter coefficient of the adaptive filter 2 based upon the switching indication. COPYRIGHT: (C)2005,JPO&NCIPI

Active vibration noise control unit

PROBLEM TO BE SOLVED: To provide an active noise reduction apparatus which is low in cost and is high in practicality as an active noise reduction apparatus for reducing random noises like load noises. SOLUTION: Active noise reduction apparatus includes a sinusoidal wave generating means 102 for generating a sinusoidal wave of a prescribed frequency, a cosine wave generating means 103 for generating the cosine wave of the same frequency as that of the sinusoidal wave generating means 102, a processing circuit 101 having two coefficient updating means 106, 107 to update the respective coefficients of two 1-tap digital filters 104, 105 by determining the outputs obtained by adding the outputs from the 1-tap digital filters 104, 105 and a control signal of the phase opposite to the phase of the original noise is generated by an adjusting circuit 108 for adjusting the phase, amplitude from the processing circuit 101. COPYRIGHT: (C)2007,JPO&INPIT

Active noise reduction apparatus

PROBLEM TO BE SOLVED: To provide an active noise processing device which mixes an audio signal and a silencing signal and reproduces the mixed signals from a speaker at a vehicle and which allows the free exchanging with general audio head units, such exchanging being heretofore not possible. SOLUTION: The ANC unit (active noise processing unit) 2 is provided with a buffer amplifier 23 and is so constituted that the audio signal amplified by a power amplifier 13 of the audio head unit 1 is subjected to level regulation by the buffer amplifier 23 and is inputted to a mixer 22 and therefore the free exchanging is possible if the unit is the audio head unit containing the power amplifier. COPYRIGHT: (C)2001,JPO

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Papers

Active type vibration noise controller

Active type noise reducing device

Active vibration noise control unit

Active noise reduction apparatus

On-vehicle noise controller

由男 中村

Papers

Active type vibration noise controller

Active type noise reducing device

Active vibration noise control unit

Active noise reduction apparatus

On-vehicle noise controller

由男中村