JP2001051685A - On-vehicle noise controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate only noise component from a sound signal containing noise signal. SOLUTION: This noise controller eliminates only the noise component from a mixed sound signal containing a sound signal S from a car stereo 29 and a noise signal N from an engine 18, and takes in the noise signal N, the sound signal S, and a prescribed control signal C through a microphone 32 arranged at a driver's seat 24, and takes out sound signal component S' which may contain slight noise component from these noise signal N, sound signal S and control signal C, and outputs an error signal E according to the difference between the sound signal component S' and the sound signal S. On the other hand, the control signal C is generated based on a prescribed reference signal R extracted from the noise source, and has almost the same amplitude as and opposite phase to the noise signal N, and this control signal C is continuously updated by an update device 40 until the error signal E is nearer to 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle noise controller, and more particularly, to an on-vehicle noise controller capable of eliminating only a noise component from a noise signal and a voice signal.

[0002]

2. Description of the Related Art In general, noise such as an engine sound enters a driver's seat space of a passenger car or the like in addition to a sound signal from a car stereo or the like, and it is difficult for the operator to hear the sound signal. That is, FIG.
As shown in (a), a noise signal N (low-frequency sine wave) such as an engine sound or a running sound enters, and these various noise signals and an audio signal S (high-frequency sine wave) from an in-vehicle audio device or the like are mixed. It is in a superimposed hybrid signal state, and it is difficult to hear the audio signal S from the in-vehicle audio equipment or the like.

[0003] For this reason, attempts have conventionally been made to eliminate only various noise signals by, for example, an active noise controller for a vehicle to make it easier to hear a sound signal from a vehicle-mounted audio device.

[0004]

However, according to the conventional noise controller, no consideration is given to the type of sound in the control space, and all sounds are to be reduced. For example, FIG. As shown in the figure, a control signal C having substantially the same amplitude and opposite phase as that of the hybrid signal obtained by superimposing the noise signal N and the audio signal S is created, and these hybrid signals and the control signal C are simply added. Therefore, as shown in FIG. 5C, there is a problem that even the necessary audio signal S is erased.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a vehicle-mounted noise controller capable of eliminating only a noise component from an audio signal including a noise signal. Is to provide.

[0006]

In order to achieve the above-mentioned object, the present invention according to claim 1 is directed to an in-vehicle audio device (2).
9) and the engine (1)
8) A vehicle-mounted noise controller capable of eliminating only a noise component from a mixed signal including a noise signal (N) generated from a noise source such as 8) extracts a predetermined reference signal (R) from the noise source. Based on the signal extracting means (36) and the reference signal (R) extracted by the signal extracting means (36), a control signal (C) having substantially the same amplitude and opposite phase as the noise signal (N) is generated. A control signal generating means (38) to be generated;
It is characterized by having.

According to a second aspect of the present invention, there is provided a mixed signal including a voice signal (S) generated from a vehicle-mounted audio device (29) and a noise signal (N) generated from a noise source such as an engine (18). In a vehicle-mounted noise controller capable of eliminating only a noise component from among the above, the noise signal (N) and the voice signal (S) are arranged in a predetermined space of a driver's seat (24).
Signal detection means (32) capable of detecting a predetermined control signal (C) and the noise signal (N) and sound signal (S) detected by the signal detection means (32); ), An audio signal component (S ′) that may include a minute noise component is extracted, and a true error corresponding to a difference between the audio signal component (S ′) that may include the minute noise component and the audio signal (S). An adder (34) for outputting a signal (E); and a control signal (R) having substantially the same amplitude and opposite phase as the noise signal (N) based on a predetermined reference signal (R) extracted from the noise source. C), and an updating means (4) capable of sequentially updating the content of the control signal (C) based on the reference signal (R) and the true error signal (E).
0).

[Operation] Based on the above-mentioned specific features of the invention, the vehicle-mounted noise controller of the present invention provides a sound signal (S) generated from an audio device such as a car radio or a car stereo (29) and an engine (18). And the like, so that only the noise component (N) can be eliminated from the mixed signal including the noise signal (N) generated from the noise source such as the above. Therefore, the noise component (N) is disposed in a predetermined space of the driver's seat (24). The noise signal (N), the audio signal (S), and a control signal (C) to be described later are detected and captured by the detected signal detection means (32).
From the noise signal (N), the audio signal (S), and the control signal (C), an audio signal component (S ′) that can include a minute noise component is extracted. Then, the audio signal component (S ′) which may include the minute noise component and the audio signal (S) are input to an adding means (34), and the adding means (34)
A true error signal (E) corresponding to these differences is output, and control is performed such that the error signal (E) approaches zero as much as possible.

The control signal (C) has substantially the same amplitude as the noise signal (N) generated by the control signal generating means (38) based on a predetermined reference signal (R) extracted from the noise source. The control signal (C) is output to the driver's seat space, and the control signal (C) is superimposed on the noise signal (N) and the audio signal (S). An audio signal component (S ′) that may include a minute noise component is extracted. And the control signal (C)
Is generated by the control signal generating means (38), and is continuously calculated by an evaluation amount obtained by the updating means (40) based on the reference signal (R) and the true error signal (E). This update control is performed until the true error signal (E) approaches zero as much as possible. In this way, it is possible to obtain a clean audio signal (S) by eliminating only the noise component from the mixed signal.

The reference numerals in parentheses described above are for the purpose of comparing the drawings, and do not limit the present invention in any way.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an agricultural tractor to which the present invention is applied. The agricultural tractor T includes a front wheel 12 and a rear wheel 14.
The engine 18 is mounted on a front part of the traveling body 16 and a driver's seat 24 having a steering wheel 20, a seat 22 and the like is arranged on a rear part. . A cabin 26 is mounted so as to cover the driver's seat 24.

As shown in FIG. 2, in the space around the operator 27 in the driver's seat 24, an audio signal output from a speaker 28 of
Active noise controller (hereafter referred to as the "active noise controller") that outputs a control signal that can eliminate only noise components in order to reduce noise while reducing the noise , "Noise controller") 10 speakers 30 are provided.

Here, according to the present invention, a signal detecting means which is arranged in a predetermined space of the driver's seat 24 and which can detect a noise signal, a voice signal, and a predetermined control signal, and which is detected by the signal detecting means. The noise signal and the audio signal, and an audio signal component that may include a minute noise component is extracted from the control signal, and a true error signal corresponding to a difference between the audio signal component and the audio signal that may include the minute noise component is extracted. It has an adding means for outputting.

For example, in FIG. 2, if C0 and C1 are transfer characteristics, y is an output signal from a control signal generation circuit 38, x is an output signal from the car stereo 29, and N is a noise signal, the noise will be described. The sound S 'observed at the operator's ear during the operation of the controller 10 is S' = N + C0.y + C1.x. Since the sound C1 · x from the car stereo 29 is a sound that does not need to be controlled, a value obtained by subtracting C1 · x from the sound S ′ immediately after being observed at the ear of the operator is regarded as a true error signal E, = 0 is performed. As a result, when E is 0, S ′ = C1 ·
x is observed, and only the noise component is eliminated.

FIG. 3 shows a control block diagram of the noise controller 10 according to the present embodiment based on feed-forward control.
A car stereo 29 is described as an audio signal source. The noise (vibration) of the engine 18 is provided on the top surface (control point) of the cabin 26 covering the driver's seat 24.
A noise signal N formed via a predetermined transfer characteristic P,
A microphone (hereinafter, referred to as “microphone”) capable of taking in an audio signal S output from the speaker 28 via a predetermined transfer characteristic C1 and a control signal C from the speaker 30 provided in the noise controller 10 to an output from the car stereo 29. ) (Signal detection means) 32 is disposed.

The noise controller 10 extracts an audio signal component S 'which may include a minute noise component from the noise signal N and the audio signal S taken by the microphone 32 and the control signal C. The difference between the audio signal component S ′ which may include the minute noise component and the audio signal S obtained by multiplying the output x from the car stereo 29 by C1 ′ (C1 is replaced by a filter) is obtained. An adder (adding means) 34 for outputting a true error signal E is provided.

On the other hand, a signal extractor (signal extracting means) 36 extracts a reference signal R which is closely related to noise such as engine vibration or engine noise or engine rotation pulse from the engine 18 as a noise source. Based on the signal R, a control signal generating circuit (control signal generating means) 38 outputs the control signal C having substantially the same amplitude and opposite phase as the noise signal N via a transfer characteristic C0. Furthermore, an updater (update means) (Leas
t Mean Square) 40, the transfer characteristics C0 ′ (C
A signal taking into account the signal obtained by replacing 0 with a filter is taken in, and a predetermined calculation (for example, a calculation of a root-mean-square value of the error signal E) is performed based on these signals, and the result is used as an evaluation amount to generate the control signal. The contents of the circuit 38 are sequentially updated.

That is, if complete control is not performed,
Since the noise is not canceled out, the content of the control signal generation circuit 38 is continuously updated by the updater 40 so that the remaining noise becomes zero.

In this embodiment, as shown in FIGS. 4A to 4C, for example, a low-frequency sine signal (see a broken line in FIG. 4A) is used as a noise signal N, and a sound signal S is used as a sound signal S. Assuming a high-frequency sine signal (see the solid line in FIG. 4A),
From the microphone 32, these noise signal N and audio signal S
And a control signal C (see FIG. 4B) from the speaker 30 of the noise controller 10 is superimposed on the hybrid signal H, and the signal H may include a minute noise component. The audio signal component S 'can be output. In addition, as the control signal C,
A signal having substantially the same amplitude and opposite phase as the noise signal N is used.

As described above, according to the present embodiment, the necessary audio signal S can be excluded from the control target and only the noise component can be eliminated from the mixed signal.

[0022]

As described above, according to the first aspect of the present invention, a control signal having substantially the same amplitude and opposite phase as a noise signal such as an engine sound is generated from a vehicle-mounted audio device. From the audio signal and the noise signal, only the noise component can be eliminated without reducing the audio signal.

According to the second aspect of the present invention, it is possible to eliminate only a noise component from a sound signal generated from an on-vehicle audio device and a noise signal such as an engine sound by excluding a necessary sound signal from a control target. Therefore, a clean audio signal can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of an agricultural tractor to which the present invention is applied.

FIG. 2 is a diagram schematically illustrating a sound observed at an ear of an operator in a driver's seat.

FIG. 3 is a control block diagram according to the present embodiment.

4A is a diagram showing a hybrid signal in which a noise signal and a sound signal are superimposed, FIG. 4B is a diagram showing a control signal, and FIG. 4C is a diagram obtained by adding these signals; FIG. 3 is a diagram showing a waveform of an audio signal obtained.

5A and 5B are diagrams showing signal waveforms by a conventional noise controller. FIG. 5A is a diagram showing a hybrid signal in which a noise signal and an audio signal are superimposed, and FIG. 5B is a diagram showing a control signal. (C) is a diagram showing a signal waveform obtained by adding these signals.

[Explanation of symbols]

 T agricultural tractor 10 noise controller 18 engine 24 driver's seat 27 operator 28 speaker (car stereo) 29 car stereo 30 speaker (noise controller) 32 microphone 34 adder 36 signal extractor 38 control signal generation circuit 40 updater

Claims (2)

[Claims] An in-vehicle noise controller capable of eliminating only a noise component from a mixed signal including a voice signal generated from a vehicle-mounted audio device and a noise signal generated from a noise source such as an engine. Signal extraction means for extracting a predetermined reference signal from a source, based on the reference signal extracted by the signal extraction means,
And a control signal generation means for generating a control signal having substantially the same amplitude and opposite phase as the noise signal. 2. An in-vehicle noise controller capable of eliminating only a noise component from a mixed signal including a voice signal generated from a vehicle-mounted audio device and a noise signal generated from a noise source such as an engine. Signal detection means that is arranged in a predetermined space and is capable of detecting the noise signal, the audio signal, and a predetermined control signal; and from the noise signal, the audio signal, and the control signal detected by the signal detection means. Adding means for extracting an audio signal component which may include a minute noise component, outputting a true error signal corresponding to a difference between the audio signal component which may include the minute noise component and the audio signal, and extracting from the noise source Control signal generating means for outputting the control signal having substantially the same amplitude and opposite phase as the noise signal based on a predetermined reference signal; and controlling the control based on the reference signal and a true error signal. Automotive noise controller, wherein sequential and updatable updating means, and a, that the contents of the issue.