Panasonic Intellectual Property Management Co., Ltd.

Panasonic Automotive Systems Co., Ltd.

Mitsuhiro Tani

Toshiyuki Funayama

Mitsuru Kaitou

Fumiyasu Konno

Kazuhisa Kotegawa

Shinnosuke Nagasawa

Yusuke Hiraga

A vehicle approach notification system includes a filter; a notification sound controller which generates a signal corresponding to a notification sound for notifying of approaching of a vehicle, based on a sound signal obtained from a notification-sound sound source; and a setter which obtains vehicle information of the vehicle, and sets, according to the vehicle information, at least one of the notification-sound sound source to be used in generation of the notification sound, a filter property to be applied to the filter, or a control parameter to be applied to the notification sound controller in generation of the notification sound. The notification sound controller outputs the signal generated, through the filter to an exterior loudspeaker provided to the vehicle.

Vehicle approach notification system and vehicle approach notification method

An active noise reduction device reduces noise in a space in an automobile. The active noise reduction device includes: a reference signal input terminal that receives a reference signal outputted by a reference signal source and having a correlation with the noise, the reference signal source being attached to the automobile; a compressor that compresses and outputs the reference signal received by the reference signal input terminal and having an amplitude greater than or equal to a threshold; an adaptive filter unit that applies an adaptive filter to the reference signal outputted from the compressor to generate a canceling signal to be used to output a canceling sound for reducing the noise; and a filter coefficient updater that updates a coefficient of the adaptive filter.

Active noise reduction device, vehicle, and active noise reduction method

An active noise reduction device includes: a reference signal input terminal that receives a reference signal from a reference signal source attached to an automobile; a simulated vibration transfer characteristics filter unit that generates a second signal by correcting, using simulated vibration transfer characteristics, a first signal for outputting, from a loudspeaker attached to the automobile, a sound different from a canceling sound, the simulated vibration transfer characteristics simulating vibration transfer characteristics from the loudspeaker to the reference signal source; a first subtracter that outputs a corrected reference signal obtained by subtracting the second signal generated, from the reference signal received by the reference signal input terminal; and an adaptive filter unit that applies an adaptive filter to the corrected reference signal outputted from the first subtracter to generate a canceling signal to be used to output the canceling sound.

An active noise reduction device includes a first adaptive filter, a first filter coefficient updater, and a controller that determines, based on a first parameter of the first adaptive filter, whether first noise control based on a first cancelling sound is in a stable state or an unstable state. The controller transitions the first filter coefficient updater to a restriction state in which an effect of reducing first noise is smaller than in a normal state when it is determined that the first noise control is in the unstable state while the first filter coefficient updater is updating a coefficient of the first adaptive filter in the normal state, and transitions the first filter coefficient updater back to the normal state when it is determined that the first noise control is in the stable state while the first filter coefficient updater is in the restriction state.

Noise reduction device, vehicle, and noise reduction method

An active noise reduction device includes: an adaptive filter that generates a cancelling signal by applying an adaptive filter to a reference signal that has a correlation with noise in a space in an automobile, the cancelling signal being used to output a cancelling sound for reducing the noise; and a filter coefficient updater that calculates a coefficient of the adaptive filter based on a predetermined update equation. At a first timing at which the output of the cancelling sound is started, the filter coefficient updater uses a first coefficient as an initial value of the update equation, the first coefficient being the coefficient of the adaptive filter calculated by the filter coefficient updater at a second timing that is prior to the first timing.

An active noise reduction device includes: a reference signal inputter; an adaptive filter; a &#x3bc; adjuster that calculates a step size parameter by multiplying a reference value for the step size parameter by a correction coefficient that is proportional to a reciprocal of a first representative input value that indicates a signal level of the reference signal in a first predetermined period; a filter coefficient updater that updates adaptive filter coefficient W by using the step size parameter calculated; and a determiner. When it is determined that a second representative input value is greater than a threshold value, at least one of the adaptive filter or the filter coefficient updater is transitioned from a normal state to a restriction state in which an effect of reducing noise is smaller than in the normal state.

An active noise control device includes: a reference signal source that outputs a reference signal having a correlation with noise; a reference signal input unit configured to receive the reference signal output from the reference signal source; a compressor that compresses the reference signal and outputs a compressed signal of the reference signal when an amplitude of the reference signal received by the reference signal input unit is greater than or equal to a threshold; and an adaptive filter unit configured to generate a canceling signal having a phase opposite to a phase of the compressed signal by multiplying the compressed signal using an adaptive filter having a coefficient that is updated successively. The coefficient of the adaptive filter is updated using a step size parameter for determining an amount of updating the coefficient of the adaptive filter based on a change in the amplitude of the reference signal.

Active noise control device, vehicle, and active noise control method

A combined reference signal generation unit included in an active noise reducing device has a plurality of filters that is applied on a one-on-one basis to the plurality of input reference signals and an adder that adds up the plurality of reference signals to which the plurality of filters is applied on a one-on-one basis to generate a combined reference signal.

Active noise reducing device, mobile device, and active noise reducing method

An active noise control device reduces noise inside a cabin of a car. The active noise control device includes: a controller that decreases a signal level of a canceling signal when a signal level of a received reference signal is lower than a threshold; and a threshold controller that changes the threshold based on at least one of a signal level of an error signal and information on the car.

Active noise control device, car, and active noise control method

According to an aspect, an active noise control device includes: a control frequency determinator that determines a frequency of the noise; a reference cosine-wave generator that generates a reference cosine-wave signal having the determined frequency; a reference sine-wave generator that generates a reference sine-wave signal having the frequency of a noise; a first one-tap adaptive filter to which the reference cosine-wave signal is input, the first one-tap adaptive filter having a first filter coefficient; a second one-tap adaptive filter to which the reference sine-wave signal is input, the second one-tap adaptive filter having a second filter coefficient; an adder that adds an output signal from the first one-tap adaptive filter and an output signal from the second one-tap adaptive filter to each other; a secondary noise generator that is driven by an output signal from the adder to generate a secondary noise; a residual sound detector that detects a residual sound generated by interference between the secondary noise and the noise; a simulation signal generator that outputs a simulation cosine-wave signal and a simulation sine-wave signal, the simulation cosine-wave signal and the simulation sine-wave signal being obtained by correcting the reference cosine-wave signal and the reference sine-wave signal using a characteristic in which a transfer characteristic from the secondary noise generator to the residual sound detector is simulated; and a filter coefficient updating unit that updates the first filter coefficient and the second filter coefficient based on an output signal from the residual sound detector, an output signal from the simulation signal generator, the reference cosine-wave signal, the reference sine-wave signal, and the output signal from the adder. The secondary noise is reduced in a space where the residual sound detector is installed.

Active noise control device

In an active noise reduction device, in order to solve this problem, a control block determines a level of a reference signal detected by a level detection unit. If determining that the level of the reference signal is small, the control block decreases a level of a cancel signal. This operation suppresses generation of an abnormal sound even if a level of a noise is small.

Active noise reduction device, instrument using same, and active noise reduction method

An active noise reduction device is used with a secondary noise source that generates a secondary noise and an error signal source that outputs an error signal corresponding to a residual sound caused by interference between the secondary noise and a noise. A &#x3bc;-adjustment unit calculates a step-size parameter for updating a filter coefficient of an adaptive filter by multiplying a standard step-size parameter by a ratio of a standard representative input value corresponding to amplitude of a signal to a representative input value corresponding to the amplitude of the signal.

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Osaka, Japan

Mitsuhiro Tani