JPH0580781A - Noise controller for vehicle - Google Patents

Abstract

PURPOSE:To prevent abnormal control even when a large-amplitude noise signal is inputted by varying the gain of the amplifier of an input stage according to the amplitude of a microphone signal and also varying the gain of the amplifier of an output signal for a speaker signal with a reciprocal number gain. CONSTITUTION:A reference sensor amplifier 6 consists of a fixed-gain linear amplifier and respective microphone speakers 8 and speaker amplifiers 11 are all composed of variable gain linear amplifiers. Respective averaging filters 14 when inputting the microphone signals e1-eM rectify and smooth them to calculate the mean effective value of the amplitudes of the microphone signals. Further, respective speaker amplifiers 11 vary output gains from the respective microphones 1 to a speaker signal generation device 4 by alpha times corresponding to the maximum value of the amplitude detected by an amplitude detector 17 so that the maximum value of the amplitude becomes large. Further, the respective microphone amplifiers 8 vary output gains from the speaker signal generation device 4 to the speakers 2 to I/alpha which is the reciprocal number of the gains of the respective speaker amplifiers 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling a predetermined vehicle noise to be low in a vehicle cabin.

[0002]

2. Description of the Related Art Conventionally, as this type of noise control device, there is one disclosed in, for example, Japanese Patent Laid-Open No. 501501/1989. This is, for example, as shown in FIG.
The M microphones 1, 1, ..., Which are arranged at predetermined positions in the vehicle interior 22 to be subjected to noise control and detect sound, and the M microphones, which are arranged at predetermined positions in the vehicle interior 22, generate sound in the vehicle interior 22 L to generate
Each of the microphones 1 is provided with a plurality of speakers 2, 2, ..., And a synthesized sound of a noise in the vehicle interior 22 and a sound emitted from each speaker 2 is generated.
And the microphone signals e1 to eM are output from the microphone 1. Speaker signal y output to each speaker 2
1 to yL is a digital filter F1 that outputs a signal called a reference signal x output from the reference sensor 3.
It is obtained by passing it through FL. The reference signal x from the reference sensor 3 is a signal obtained from a vehicle noise source such as engine noise or running noise, and has a high correlation with the noise. For example, in the case of engine noise, by using the reference sensor 3 as an acceleration sensor of the engine and using the output thereof as the reference signal x, the engine noise that changes according to the operating state of the engine is controlled.

Reference numeral 4 denotes output signals y1 to yL to the speakers 2 by operating the digital filters F1 to FL.
Is a speaker signal generating device including a CPU for generating the digital signal so that the adaptive algorithm section 5 of the speaker signal generating device 4 minimizes the sum of squares of the synthetic sound signals detected by the microphones 1. The parameters of the filters F1 to FL are automatically adjusted. As an algorithm for this adjustment, Least Mean Squar
e Method (= LMS) is performed, and by this adjustment, the output signals y1 to yL to each speaker 2 are reduced so that the sound detected by each microphone 1 is reduced based on the reference signal x from the reference sensor 3. To generate. The reference signal x is a digital filter

[0004]

[Equation 1]

Is input to the adaptive algorithm section 5 via

[0006]

[Equation 2]

Is a modeled transfer characteristic between the Lth speaker 2 and the Mth microphone 1.

In the speaker signal generator 4, since the signal processing is performed by digital calculation, the reference sensor amplifier 6 and the A / D converter 7 which are linear amplifiers and the microphone signal e are provided at the input stage of the reference signal x.
Similar microphone amplifiers 108, 10 are provided at the input stages of 1 to eM.
, And A / D converters 9, 9, ..., Further, D / A converters 10, 10, at the output stages of the speaker signals y1 to yL.
... and speaker amplifiers 111 and 11 composed of linear amplifiers
1, ... Are provided respectively, and the reference signal x, which is an analog signal output from the reference sensor 3, is amplified by the reference sensor amplifier 6 and then digitally converted by the A / D converter 7 to generate a speaker signal. Input to the device 4. Further, the microphone signals e1 to eM, which are analog signals output from the microphones 1, are amplified by the microphone amplifier 108, respectively, and then A / A
The signal is digitally converted by the D converter 9 and input to the speaker signal generation device 4. Further, the speaker signal generation device 4
The digital signals output from the respective D / A converters 1
After being converted to analog speaker signals y1 to yL by 0, they are amplified by the speaker amplifier 111 and output to each speaker 2.

[0009]

By the way, in the above-mentioned conventional device, the resolution of the A / D converters 7 and 9 and the width of the value after conversion, and the resolution of the D / A converter 10 and the value before conversion. Since the range of possible values is finite, it is required that the resolution and the dynamic range of the A / D converters 7 and 9 and the D / A converter 10 are compatible with each other. That is, if the gain of the speaker amplifier 111 is lowered and the gain of the microphone amplifier 108 is increased, assuming that only a signal of a noise of a small amplitude is input, the resolution is emphasized, and when a noise of a large amplitude is generated, the noise for the speaker D
Saturation occurs in both the A / A converter 10 and the microphone A / D converter 9, normal control is not performed, and the sound generated by the speaker 2 becomes abnormal.

On the contrary, if the gain of the speaker amplifier 111 is increased and the gain of the microphone amplifier 108 is decreased on the assumption of a large amplitude signal, the control for small amplitude noise becomes relatively rough. There arises a problem that the control accuracy is lowered and a good silencing performance cannot be obtained.

The present invention has been made in view of the above points, and an object thereof is to change the characteristics of the amplifiers provided at the input stage of the microphone signal and the output stage of the speaker signal, respectively, to thereby obtain the A / D converter. And maintaining the resolution of the D / A converter excellent, and preventing abnormal control by saturation even when a noise signal of large amplitude is input.

[0012]

In order to achieve the above object, the invention of claim 1 detects the amplitude of a microphone signal,
The gain of the amplifier at the input stage of the microphone signal is changed according to the magnitude of this amplitude, and the gain of the amplifier at the output stage of the speaker signal is changed by a reciprocal gain.

Specifically, in the present invention, a vehicle interior sound detecting means for detecting a sound in the vehicle interior, a speaker for producing a sound in the vehicle interior, and a reference signal related to vibration of a predetermined noise source in the vehicle are provided. Reference signal output means for outputting and speaker signal generation means for generating an output signal to the speaker based on the reference signal from the reference signal output means so as to reduce the sound detected by the vehicle interior sound detection means. A vehicle noise control device is a prerequisite.

On the basis of this premise, the amplitude detection means for detecting the amplitude of the output signal of the vehicle interior sound detection means and the output gain from the vehicle interior sound detection means to the speaker signal generation means are detected by the amplitude detection means. And a second gain changing means for changing the output gain from the speaker signal generating means to the speaker to a reciprocal gain of the first gain changing means.

According to the second aspect of the present invention, a plurality of the vehicle interior sound detecting means are provided, and the amplitude detecting means is configured to detect the maximum amplitude value of the output signals from the plurality of vehicle interior sound detecting means.

According to the third aspect of the present invention, a plurality of vehicle interior sound detecting means are provided in the same manner as described above, and the amplitude detecting means is configured to detect the average amplitude value of the output signals from the plurality of vehicle interior sound detecting means. ..

[0017]

With the above construction, in the first aspect of the invention, the sound signal from the vehicle interior sound detecting means is input to the speaker signal generating means after passing through the first gain changing means, and on the other hand, from the speaker signal generating means. The speaker signal output to the speaker is output to the speaker via the second gain changing means. In the first gain changing means, the output gain of the vehicle interior sound detecting means is changed according to the amplitude of the output signal of the vehicle interior sound detecting means. Higher control accuracy can be maintained by increasing the gain. On the other hand, when a large amplitude signal is generated,
By reducing the gain of the same first gain changing means,
It can prevent abnormal operation due to saturation. Also,
At this time, in the second gain changing means, the output gain of the speaker signal generating means is changed to a gain that is the reciprocal of the first gain changing means, so that the transfer characteristic from the speaker input stage to the output stage of the room sound detecting means. Can be kept constant. Therefore, by slightly increasing the calculation amount in the control device,
The controllable noise area can be expanded.

According to the second aspect of the present invention, since the amplitude detecting means detects the maximum amplitude value of the output signals from the plurality of vehicle interior sound detecting means, it is possible to stably prevent saturation with respect to noise of large amplitude.

According to the invention of claim 3, the amplitude detecting means detects the average value of the amplitudes of the output signals from the plurality of vehicle interior sound detecting means, so that the signal processing becomes simpler than that of the invention of claim 2.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Since the basic configuration of the vehicle noise control device according to this embodiment is the same as that of the conventional example, the same parts as those in FIG. 5 are designated by the same reference numerals and the detailed description thereof will be omitted.

(Embodiment 1) That is, this control device
As shown in FIG. 1, M microphones 1, 1, ..., L speakers 2, 2, ..., A reference sensor 3 for outputting a reference signal x related to vibration of a predetermined noise source in the vehicle, Based on the reference signal x from the reference sensor 3, the output signal y1 to each speaker 2 is reduced so that the sound detected by each of the microphones 1, 1, ... Is reduced.
A speaker signal generating device 4 including a CPU for generating yL.

FIG. 3 concretely exemplifies a layout of the above-mentioned devices 1 to 4 in an automobile, in which 21 is a vehicle body, 22 is a vehicle compartment provided in a central portion of the vehicle body 21, and 23 to 26 are opening and closing the vehicle compartment 22. As a door, a pair of left and right front seats 27 and 28 are installed on the front side in the vehicle compartment 22, and one rear seat 29 is installed on the rear side. 30 is a steering wheel. Headrests 27a, 2 in the front seats 27, 28
Left and right sides of 8a (positions near the ears of passengers seated in the front seats 27 and 28) and left and right headrests 29 of the rear seat 29.
A total of four microphones (when M = 4) are attached to the left and right sides of a and 29a (positions near the ears of the occupants seated on the left and right sides of the rear seat 29). The sound in the passenger compartment 22 of the automobile is detected by 1, ... Near the ears of the passenger.

Further, the number of speakers 2 for producing a sound in the vehicle compartment 22 is five (when L = 5), and the left and right front doors 2 of the instrument panel at the front end of the vehicle compartment 22 are arranged in the left-right center.
The speakers 3 and 24 are disposed on the inner side surfaces of the vehicle compartment and on the left and right sides of the package tray portion at the rear end of the vehicle compartment 22, and these speakers 2, 2, ... Are also used for audio.

The reference sensor 3 is arranged in the engine room and is composed of an acceleration sensor for detecting the operating state of the engine. By using the output of the acceleration sensor as the reference signal x, the reference sensor 3 changes according to the operating state of the engine. Control engine noise as noise.

The controller 12 for controlling the audio output of the speakers 2, 2, ... Is a left front seat 28 on the passenger side.
It is located inside the instrument panel in the front. In the controller 12, the speaker signal generation device 4 is provided.
, A reference sensor amplifier 6 for amplifying the reference signal x from the reference sensor 3, an A / D converter 7 for converting the signal x into a digital signal, and a microphone amplifier 8 for amplifying the microphone signals e1 to eM from the microphones 1, respectively. , 8, ... and A for digitally converting the signals e1 to eM
./D converters 9, 9, ..., and digital filters F1 to FL
D / A converters 10 and 10 for converting the reference signal x passing through to the analog speaker signals y1 to yL.
, And speaker amplifiers 11, 11, ... Which amplify the same signals y1 to yL and output them to each speaker 2.

Further, in the controller 12, an operation switch 13 for switching the operation of the noise control system and the audio system by the speaker signal generating device 4 is arranged on the roof portion of the passenger compartment.

As a feature of the present invention different from the conventional one, the reference sensor amplifier 6 is composed of a linear amplifier with a fixed gain as in the conventional one, but each microphone amplifier 8 and speaker amplifier 11 are variable. It consists of a linear gain amplifier. The output signal of each microphone 1 is also input to the averaging filter 14 in addition to the microphone amplifier 8. Each averaging filter 1
4 is the microphone signals e1 to eM as shown in FIG.
When is input, it is rectified as shown in FIG. 2 (b), further smoothed as shown in FIG.
The average effective value of the amplitudes of the microphone signals e1 to eM is calculated. The output signal of each averaging filter 14 is input to the maximum value detector 15, and this detector 15 detects the maximum value of the average effective values of the M signal amplitudes. The output signal of the maximum value detector 15 is a gain adjuster 1 for adjusting the gains of the microphone amplifiers 8 and speaker amplifiers 11 described above.
6, the gain adjuster 16 increases the gain of each speaker amplifier 11 by, for example, α times as the maximum value of the amplitude detected by the maximum value detector 15 increases, and the gain of each microphone amplifier 8 increases. The gain is reduced to 1 / α times.

In this embodiment, each averaging filter 1 described above is used.
4 and the maximum value detector 15 constitute an amplitude detecting means 17 for detecting the maximum value as the amplitude of the output signals e1 to eM of each microphone 1.

Further, by the above speaker amplifiers 11,
The output gain from each microphone 1 to the speaker signal generation device 4 is changed to α times according to the maximum value of the amplitude detected by the amplitude detector 17, and is changed so as to increase as the maximum value of the amplitude increases. Gain changing means is configured.

Further, each microphone amplifier 8 changes the output gain from the speaker signal generating device 4 to the speaker 2 to a gain that is 1 / α times the reciprocal of the gain of each speaker amplifier 11 (first gain changing means). The second gain changing means is configured. Others are the same as the conventional example (see FIG. 5).

Therefore, in the above embodiment, when the noise control system is operated by the operation switch 13, the reference signal x which is an analog signal output from the reference sensor 3 is amplified by the reference sensor amplifier 6 and then The signal is digitally converted by the A / D converter 7 and input to the speaker signal generation device 4.
Similarly, the microphone signals e1 to eM, which are analog signals output from the microphones 1, are similarly amplified by the microphone amplifiers 8, 8, ... As the first gain changing means, and then the A / D converters 9, Are converted into digital signals by 9, ... And inputted to the speaker signal generation device 4. Further, the digital signal generated by passing the reference signal x through the digital filters F1 to FL in the speaker signal generator 4 is converted into analog speaker signals y1 to yL by the D / A converters 10, 10, .... The speaker signals y1 to yL are amplified by the speaker amplifiers 11, 11, ... As the second gain changing means and output to the speakers 2.

The gain of each microphone amplifier 8 is changed according to the maximum amplitude value of the output signals e1 to eM of each microphone 1. When the maximum value is small, the gain of the microphone amplifier 8 is increased, and when it is large, the gain is increased. Microphone amplifier 8
The gain of is changed to a small value. Therefore, it is possible to improve and maintain the control accuracy for a small amplitude noise signal, and at the same time, prevent abnormal operation due to saturation when a large amplitude signal is generated.

Further, the gain of each speaker amplifier 11 is changed to a gain which is 1 / α times the reciprocal of the gain of the microphone amplifier 8 which is α times. The transfer characteristic up to the output stage of the microphone amplifier 8 can be maintained constant. Therefore, the controllable noise region can be expanded by slightly increasing the calculation amount of the entire control device.

Further, in this embodiment, since the speaker 2 in the existing audio device is used, it is only necessary to add the microphone 1, the reference sensor 3, the speaker signal generating device 4, etc. to the audio device, which is inexpensive. it can.

(Embodiment 2) FIG. 4 shows Embodiment 2 in which the maximum value detector 15 in Embodiment 1 is used to calculate the average value of the output signals of a plurality of averaging filters 14, 14 ,. It replaces with the average value detector 18 for detecting, and in this average value detector 18, the averaging filters 14, 14, ...
The average value of the average effective values of the signal amplitudes passing through is detected.
In other words, the amplitude detecting means 17 'composed of each averaging filter 14 and average value detector 18 detects the average value as the amplitude of the output signals e1 to eM of each microphone 1.

Therefore, also in this embodiment, the same operational effect as that of the first embodiment can be obtained. Comparing the first and second embodiments, since the maximum value of the signal amplitude is detected in the first embodiment,
Saturation can be reliably and stably prevented even if the noise has a large amplitude. On the other hand, in the second embodiment, since the average value of the signal amplitude is detected, there is an advantage that the signal processing is simplified.

In each of the above embodiments, engine noise is controlled as a concrete example of vehicle noise.
For example, traveling noise can be targeted. In that case,
An acceleration sensor arranged on the suspension is used as a reference sensor, and its output signal can be used as a reference signal.

The present invention can of course be applied to vehicles other than automobiles.

[0039]

As described above, according to the invention of claim 1, the vehicle interior sound detecting means for detecting the sound in the vehicle interior and the speaker for generating the sound in the vehicle interior are provided, and the predetermined noise in the vehicle is provided. The noise detection device for a vehicle is configured to generate an output signal to a speaker so that the sound detected by the vehicle interior sound detection unit is reduced based on a reference signal related to the source vibration. The amplitude of the output signal of the means is detected by the amplitude detection means, the output gain from the vehicle interior sound detection means to the speaker signal generation means is changed according to the amplitude of the output signal of the vehicle interior sound detection means, and the speaker signal generation means is also provided. Since the output gain from the speaker to the speaker is changed to the reciprocal gain from the above, the output gain from the vehicle interior sound detection means to the speaker signal generation means for a small amplitude signal. While capable of maintaining emissions increased to a high-precision control accuracy, when the signal of large amplitude is generated, by reducing the same gain can prevent the abnormal operation of the saturation can highly achieve both resolution and dynamic range. Further, since the output gain from the speaker signal generating means to the speaker is changed to the reciprocal of the gain of the output signal from the vehicle interior sound detecting means to the speaker signal generating means, the output from the speaker input stage to the indoor sound detecting means. The transfer characteristic up to the stage can be maintained constant, so that the controllable noise region can be expanded by slightly increasing the amount of calculation in the entire device.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric circuit showing an overall configuration of a noise control device according to a first embodiment of the present invention.

FIG. 2 is an operating characteristic diagram of an averaging filter.

FIG. 3 is a plan view showing a layout of devices for an automobile.

FIG. 4 is a view corresponding to FIG. 1 showing a second embodiment.

FIG. 5 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microphone (vehicle interior sound detection means) 2 ... Speaker 3 ... Reference sensor (reference signal output means) 4 ... Speaker signal generation device 6 ... Reference sensor amplifier 7, 9 ... A / D converter 8 ... Microphone amplifier (1st) Gain changing means) 10 ... D / A converter 11 ... Speaker amplifier (second gain changing means) 12 ... Controller 14 ... Averaging filter 16 ... Gain adjuster 17, 17 '... Amplitude detecting means 22 ... Vehicle compartment x ... Reference Signals e1 to eM ... Microphone signals y1 to yL ... Speaker signals

Claims (3)

[Claims] 1. A vehicle interior sound detecting means for detecting a sound in the vehicle interior, a speaker for producing a sound in the vehicle interior, and a reference signal output means for outputting a reference signal related to vibration of a predetermined noise source in the vehicle. A vehicle noise control device comprising: a speaker signal generation unit that generates an output signal to a speaker based on a reference signal from the reference signal output unit so that a sound detected by the vehicle interior sound detection unit is reduced. An amplitude detection means for detecting the amplitude of the output signal of the vehicle interior sound detection means, and an output gain from the vehicle interior sound detection means to the speaker signal generation means are changed according to the amplitude detected by the amplitude detection means. The first gain changing means and the output gain from the speaker signal generating means to the speaker are the reciprocal gains of the first gain changing means. Second to change to
A vehicle noise control device comprising: a gain changing unit. 2. A plurality of vehicle interior sound detecting means are provided, and the amplitude detecting means is configured to detect an amplitude maximum value of output signals from the plurality of vehicle interior sound detecting means. Item 1. The vehicle noise control device according to item 1. 3. A plurality of vehicle interior sound detecting means are provided, and the amplitude detecting means is configured to detect an average amplitude value of output signals from the plurality of vehicle interior sound detecting means. Item 1. The vehicle noise control device according to item 1.