JPH10333687A - Noise reducing device in car interior - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise of a rear seat and eliminate the effect on a front seat, by setting a second correcting circuit to offset the sound pressure by the acoustic output from a rear speaker on the front seat side with the acoustic output of a front speaker. SOLUTION: The noise signal near a rear seat detected by a microphone 101 is amplified by the first amplifier 103 through the first correcting circuit 102, and it is radiated in a car interior as the acoustic output by the speaker 104 of a rear tray. The first correcting circuit 102 is set so that the acoustic output radiated from the speaker 104 becomes opposite in phase to the original noise at the position of the microphone 101 in the frequency range reduced in the noise. The signal of the microphone 101 is amplified by the second amplifier 106 through the second correcting circuit 107, and it is radiated as the acoustic output from a speaker 105 of a front door. The second correcting circuit 107 is set so that the sound pressure as the front seat from the speaker 105 negates the sound pressure as the front seat from the speaker 104 in the opposite phases with nearly the same sound pressure characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle interior noise reduction device, and more particularly to a vehicle interior noise reduction device for actively reducing a periodic sound of 100 Hz or less that causes a muffled feeling.

[0002]

2. Description of the Related Art It is considered that noise in a vehicle cabin is generated when the wall surface of the vehicle cabin which forms a closed space is vibrated by vibrating force due to rotation of an engine or force transmitted from a road during traveling.

Conventionally, to reduce such noise in the vehicle interior, passive (passive) means such as increasing the rigidity of various parts of the vehicle body and performing tuning on a transmission system have been mainly used. There were many problems such as increase and cost increase.

On the other hand, a speaker and a microphone are installed in the vehicle interior, and a noise signal in the vehicle interior detected by the microphone is fed back to an amplifier for driving the speaker, and a sound wave having a phase opposite to the noise is generated from the speaker, and a sound near the microphone is generated. Although an active device that reduces noise has been proposed, in the case of this conventional device, the noise near the microphone decreases, but the noise increases at a point farther from other microphones. However, it has not been put to practical use.

[0005]

With respect to the reduction of vehicle interior noise, there is a need for an active noise reduction device which is low cost and effective at both front and rear seats.

As described above, in a device in which a microphone and a speaker are installed in a vehicle cabin and the noise in the vehicle cabin detected by the microphone is fed back to an amplifier that drives the speaker, noise near the microphone is reduced. For example, when a microphone is placed near the rear seat and the noise near the rear seat is reduced, the sound output from the speaker affects the front seat, and conversely, the noise increases in the front seat. Was.

[0007] The present invention relates to such a vehicle interior noise reduction apparatus, and an object thereof is to reduce the interference between the front and rear seats so that the reduction effect can be obtained for all the seats at low cost.

[0008]

A vehicle interior noise reduction device according to the present invention is installed near a rear seat in a vehicle interior, detects a noise near the rear seat, and detects the phase and amplitude of a signal from the microphone. Correction circuit that appropriately corrects the signal, and a first circuit that amplifies a signal of the first correction circuit and drives a speaker.
And a rear speaker installed on a rear tray that is driven by an electric output from the first amplifier and emits an acoustic output into the vehicle cabin, and a second speaker that appropriately corrects the phase and amplitude of the signal from the microphone. Correction circuit and the second
A second amplifier that amplifies the signal of the correction circuit of the above and drives a speaker, and a front speaker that is driven by an electric output from the second amplifier and that is arranged at a front door that radiates as an acoustic output into the vehicle interior. And the second correction circuit is set so that the sound pressure generated by the sound output from the rear speaker on the front seat side is canceled by the sound output from the front speaker. In addition to the reduction, the adverse effect on the front seats is eliminated, and an effective vehicle interior noise reduction device can be realized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An invention according to claim 1 of the present invention is provided with a microphone installed near a rear seat in a vehicle cabin for detecting noise near the rear seat, and a phase and amplitude of a signal from the microphone. A first correction circuit for appropriately correcting
A first amplifier that amplifies the signal of the correction circuit and drives a speaker; a rear speaker that is driven by an electric output from the first amplifier and is installed on a rear tray that emits an acoustic output into a vehicle cabin; A second correction circuit for appropriately correcting the phase and amplitude of the signal from the second amplifier, a second amplifier for amplifying the signal of the second correction circuit and driving the speaker, and an electric output from the second amplifier. Driven,
A front speaker disposed at a front door that radiates as sound output into the vehicle interior, wherein the sound pressure generated by the sound output from the rear speaker on the front seat side is canceled by the sound output from the front speaker. A second correction circuit is provided, which has the effect of reducing noise in the rear seat and reducing the adverse effect of increasing noise in the front seat.

According to a second aspect of the present invention, there is provided a microphone installed near a front seat in a vehicle interior for detecting noise near the front seat, and adjusting the phase and amplitude of a signal from the microphone. , A first amplifier that amplifies the signal of the first correction circuit and drives a speaker, and is driven by an electrical output from the first amplifier, and is output as an acoustic output in the vehicle cabin. A front speaker installed at the front door that emits light, a second correction circuit that appropriately corrects the phase and amplitude of a signal from the microphone, and a second driver that amplifies the signal of the second correction circuit and drives the speaker. And a rear speaker that is driven by an electric output from the second amplifier and is disposed on a rear tray that emits an acoustic output into the vehicle interior. The second correction circuit is set so as to cancel the sound pressure generated by the sound output from the rear speaker, thereby reducing the noise in the front seat and increasing the noise in the rear seat. This has the effect of reducing the adverse effect of doing so.

According to a third aspect of the present invention, there is provided a first microphone installed near a rear seat in a vehicle compartment for detecting noise near the rear seat, and a first microphone installed near a front seat in the vehicle interior. A second microphone for detecting noise near the front seat,
A first correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone, a first amplifier for amplifying a signal of the first correction circuit and driving a speaker, and a first amplifier A rear speaker mounted on a rear tray that is driven by an electric output from the vehicle and emits an acoustic output into the vehicle interior, a second correction circuit that appropriately corrects the phase and amplitude of a signal from the second microphone, A third correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone, and a third driver for amplifying a signal obtained by adding the outputs of the second and third correction circuits to drive a speaker. And a front speaker disposed at a front door driven by an electric output from the second amplifier and radiated as an acoustic output into the vehicle interior, and a sound output from a rear speaker on a front seat side. To The third correction circuit is set so as to cancel the sound pressure generated by the sound output from the front speaker by the sound output from the front speaker, and thereby the rear seat, the rear seat generated when the noise near the front seat is reduced. This has the effect of reducing the adverse effect of increased noise on the front seat.

According to a fourth aspect of the present invention, there is provided a first microphone installed near a front seat in a vehicle interior for detecting noise near the front seat, and a first microphone installed near a rear seat in the vehicle interior. A second microphone installed to detect noise near the rear seat;
A first correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone, a first amplifier for amplifying a signal of the first correction circuit and driving a speaker, and a first amplifier And a second correction circuit for appropriately correcting the phase and amplitude of the signal from the front microphone and the second microphone installed on the front door that is driven by the electric output from and radiates as a sound output into the vehicle interior, A third correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone, and amplifying a signal obtained by adding outputs from the second and third correction circuits to drive a speaker. A second amplifier, and a rear speaker driven by an electric output from the second amplifier and arranged on a rear tray that radiates as an acoustic output into a vehicle interior; and a sound output from a front speaker on a rear seat side. Therefore, the third correction circuit is set so that the generated sound pressure is canceled by the sound output from the rear speaker, and thereby the front seat generated when the noise near the rear seat and the front seat is reduced. This has the effect of reducing the adverse effect of increased noise on the rear seats.

(First Embodiment) FIG. 1 is a structural view of a first embodiment of a vehicle interior noise reduction device according to the present invention. In FIG. 1, reference numeral 101 denotes a microphone that is disposed in a vehicle interior and detects noise, and 102 is a first microphone that corrects a signal from the microphone 101.
Is a first amplifier that amplifies the output from the first correction circuit 102 and drives a speaker. 1
Reference numeral 04 denotes a rear speaker that is arranged on the rear tray, is driven by the first amplifier 103, and emits an acoustic output into the vehicle interior. 105 is a front speaker arranged at the front door, and 106 is a second speaker for driving the front speaker 105.
Reference numeral 107 denotes a second correction circuit connected to a stage preceding the amplifier 106 and correcting a signal from the microphone 101. Reference numeral 108 denotes a point at the ear position of the person who gets on the front seat.

FIG. 3 is a characteristic diagram of vehicle interior noise during traveling. Numeral 301 indicates noise in the front seat, and numeral 302 indicates noise in the rear seat. FIG. 4A is a characteristic diagram showing the effect of reducing vehicle interior noise in the rear seats according to the first embodiment.
(B) is a characteristic diagram showing the effect of reducing vehicle interior noise at the front seat in the first embodiment. 4A and 4B, reference numeral 401 denotes a vehicle interior noise in a rear seat, 402 denotes noise when only the speaker 104 is operated, and 403 denotes a noise.
Indicates noise when both speakers 104 and 105 are operated. 404 indicates the vehicle interior noise at the front seat,
05 indicates the noise when only the speaker 104 is operated, and 406 indicates the noise when both the speakers 104 and 105 are operated. 407 indicates the sound pressure generated by the speaker 104 at the point 108, and 408 indicates the sound pressure generated by the speaker 105 at the point 108 as well.

Next, the operation of the first embodiment of the present invention will be described below. A noise signal in the vicinity of the rear seat detected by the microphone 101 passes through a first correction circuit 102, is amplified by a first amplifier 103, and is emitted as acoustic output into a vehicle interior by a speaker 104 arranged on a rear tray. The first correction circuit 102 is set so that the acoustic output radiated from the speaker 104 in the frequency range to be reduced in the noise has a phase opposite to that of the original noise at the position of the microphone 101. At this time, the microphone 101
(Rear seat), the noise decreases as indicated by 402 in FIG. 4A, but the noise increases in the front seat, as indicated by 405 in FIG. 4B. This causes sound output from the speaker 104 to be radiated so as to reduce noise in the rear seat, and this is transmitted to the front seat as indicated by 407 in FIG. 4B and overlaps with the original noise. It is considered that the noise in the front seat increases.

On the other hand, at the same time as the above operation, the signal of the microphone 101 is passed through the second correction circuit 107 and
Amplified at 6, and radiated as sound output from a speaker 105 installed at the front door. At this time, the second correction circuit 10
7 shows the sound pressure at the front seat from the speaker 105 as shown in FIG.
In order to cancel the sound pressure at the front seat from the speaker 104 shown by 407 in FIG. 4B, the sound pressure characteristics are set to be almost the same as 408 in FIG. I do.

By doing so, 40 in FIG.
As shown in FIG. 3, the noise reduction effect at the rear seat is shown in FIG.
Although slightly reduced from 402 in (a), the sound pressure from the speaker 104 is canceled in the front seat to reduce noise in the rear seat, and as can be seen from comparison with 405 in FIG. As shown by 406 in FIG. 4B, the increase in noise at the front seat is very small.

As described above, according to this embodiment, an advantageous effect can be obtained in that an increase in noise at the front seat, which is caused to reduce noise at the rear seat, can be suppressed.

In the first embodiment, the case where the microphone 101 is arranged near the rear seat has been described.
It is needless to say that the present invention can be similarly applied to a case where 01 is arranged near the front seat.

(Embodiment 2) FIG. 2 is a structural view of a vehicle interior noise reduction apparatus according to Embodiment 2 of the present invention. In FIG. 2, reference numeral 201 denotes a first microphone arranged near the rear seat of the vehicle cabin and detecting noise near the rear seat; 202, a first correction circuit for correcting a signal from the first microphone 201; Is a first amplifier that amplifies a signal from the first correction circuit 202 and drives a speaker. Reference numeral 204 denotes a rear speaker arranged on a rear tray which is driven by the first amplifier 203 and emits an acoustic output into the vehicle interior. 20
Reference numeral 5 denotes a second microphone arranged near the front seat in the vehicle interior and detecting noise near the front seat, and reference numeral 206 denotes a second correction circuit for correcting a signal from the second microphone 205.
Reference numeral 207 denotes a third correction circuit that corrects the signal of the first microphone 201, and reference numeral 208 denotes a second amplifier that adds and amplifies the outputs from the second correction circuit 206 and the third correction circuit 207. Reference numeral 209 denotes a front speaker arranged at the front door, which is driven by the second amplifier 208. 210
Indicates a point at the ear position of the person in the front seat.

FIG. 5A is a characteristic diagram showing the effect of reducing the interior noise of the rear seat in the second embodiment, and FIG. 5B is a diagram showing the effect of reducing the interior noise of the front seat in the second embodiment. FIG. 5A and 5B, 5
01 indicates the noise in the passenger compartment at the rear seat, 502 indicates the noise when operated without the third correction circuit 207, and 503 indicates the noise with the third correction circuit 207. Reference numeral 504 denotes the vehicle interior noise at the front seat,
Reference numeral 5 denotes noise when the apparatus is operated without the third correction circuit 207, and reference numeral 506 denotes noise when the third correction circuit 207 is provided. 507 indicates a sound pressure generated by the rear speaker 204 at a point 210,
Is the third correction circuit 20 at the same 210 point.
7 shows the sound pressure generated by the front speaker 209 when there is no 7;
Speaker 209 when there is a correction circuit 207 of
Indicates the sound pressure generated by

Next, the operation of the second embodiment of the present invention will be described below. In the second embodiment, the noise signal in the vicinity of the rear seat detected by the first microphone 201 is passed through the first correction circuit 202 and the first amplifier 2
The signal is amplified at 03 and radiated into the vehicle interior as acoustic output by the rear speaker 204. The first correction circuit 202 outputs the sound output radiated from the rear speaker 204 in the frequency range to be reduced in the noise of the rear seat,
The microphone 201 is set so as to have a phase opposite to that of the original noise at the position of the microphone 201. Further, a noise signal near the front seat detected by the second microphone 205 is passed through a second correction circuit 206,
Amplified by the second amplifier 208, the front speaker 20
9 radiates into the vehicle interior as acoustic output. In the second correction circuit 206, in the front seat noise, the sound output radiated from the front speaker 209 in the frequency range to be reduced has a phase opposite to that of the original noise at the position of the second microphone 205. It is set as follows. At this time, in the rear seat, noise is reduced as indicated by 502 in FIG. In the front seat, as shown by 505 in FIG. 5B, a noise reduction effect is obtained in a band set to be effective by the second correction circuit 206, but a band in which noise increases is also generated. This is to reduce the rear seat noise
04 emits sound output, which is
It is considered that the noise is transmitted as indicated by 507 in (b) and overlaps with the original noise, so that the noise increases in the front seat. On the other hand, at the same time as the above operation, the signal of the first microphone 201 is passed through the third correction circuit 207, added to the output of the second correction circuit 206, amplified by the second amplifier 208, and installed at the front door. The sound is radiated from the front speaker 209 as an acoustic output. At this time, the third correction circuit 207 adjusts the sound pressure at the front seat from the front speaker 209 to 5 in FIG.
In order to cancel out the sound pressure at the front seat from the rear speaker 204 indicated by reference numeral 07, the sound pressure characteristics are set so as to be opposite in phase with almost the same sound pressure characteristics as indicated by 509 in FIG. 5B.

Note that reference numeral 508 in FIG. 5B denotes the sound pressure at the front seat by the front speaker 209 when the third correction circuit 207 is not provided, and the signal from the third correction circuit 207 is added. The result is as shown by 509 in FIG. By doing so, as shown by 503 in FIG. 5A, the noise reduction effect in the rear seat is slightly reduced as compared with 502 in FIG. 5A, but the noise in the rear seat is reduced in the front seat. As a result, the sound pressure at the front seat due to the acoustic output radiated from the rear speaker 204 is canceled out, and as can be seen from the comparison with 505 in FIG.
The increase in noise in the front seats, as in 506, is negligible.

As described above, according to the present embodiment, an advantageous effect can be obtained in that an increase in noise at the front seat, which is caused by reducing noise at the rear seat, can be reduced.

In the second embodiment, the third correction circuit 20
7 is a description of the case where the signal of the first microphone 101 is corrected and added to the signal of the second correction circuit 206 to drive the front speaker 209. The third correction circuit 207 outputs the signal of the second microphone 205. , And is added to the signal of the first correction circuit 202 to drive the rear speaker 204.

[0026]

As described above, according to the present invention, it is possible to reduce the interference between the front seat and the rear seat, which is caused when the noise in the vehicle interior is reduced. An improved vehicle interior noise reduction device can be realized.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a vehicle interior noise reduction device according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a vehicle interior noise reduction device according to a second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing an example of vehicle interior noise when the vehicle is running.

4A is a characteristic diagram showing a noise reduction effect in a rear seat of the vehicle interior noise reduction device according to the first embodiment of the present invention. FIG. 4B is a front view of the vehicle interior noise reduction device according to the first embodiment of the present invention. Diagram showing the noise reduction effect of

FIG. 5 (a) is a characteristic diagram showing a noise reduction effect in a rear seat of the vehicle interior noise reduction device according to the second embodiment of the present invention. (B) A front seat of the vehicle interior noise reduction device according to the second embodiment of the present invention. Diagram showing the noise reduction effect of

[Explanation of symbols]

 101 microphone 102 correction circuit 103 amplifier 104 speaker 105 speaker 105 speaker 106 amplifier 107 correction circuit 201 microphone 202 correction circuit 203 amplifier 204 speaker 206 correction circuit 207 correction circuit 208 amplifier 209 speaker

Claims (4)

[Claims] 1. A microphone installed near a rear seat of a vehicle interior for detecting noise near the rear seat, a first correction circuit for appropriately correcting the phase and amplitude of a signal from the microphone, A first amplifier for amplifying a signal of the first correction circuit to drive a speaker, a rear speaker mounted on a rear tray driven by an electric output from the first amplifier, and radiating as an acoustic output into a vehicle cabin; A second correction circuit for appropriately correcting the phase and amplitude of the signal from the microphone, a second amplifier for amplifying the signal of the second correction circuit and driving the speaker, and an electric output from the second amplifier And a front speaker disposed at a front door that is driven by the front speaker and radiates as sound output into the vehicle interior. The sound pressure generated by the sound output from the rear speaker on the front seat side is output from the front speaker. Wherein the second correction circuit is set so as to be canceled by the acoustic output of the vehicle interior. 2. A microphone installed near a front seat in a vehicle interior for detecting noise near the front seat, a first correction circuit for appropriately correcting the phase and amplitude of a signal from the microphone, A first amplifier for amplifying a signal of the first correction circuit and driving a speaker, and a front amplifier mounted on a front door driven by an electric output from the first amplifier and radiating as an acoustic output into a passenger compartment. A speaker, a second correction circuit for appropriately correcting the phase and amplitude of the signal from the microphone,
A second amplifier that amplifies the signal of the second correction circuit and drives a speaker; and a rear speaker that is driven by an electric output from the second amplifier and that is disposed on a rear tray that emits an acoustic output into a vehicle cabin. Wherein the second correction circuit is set such that sound pressure generated by sound output from a front speaker on the rear seat side is canceled by sound output from a rear speaker. 3. A first microphone installed near the rear seat of the vehicle interior to detect noise near the rear seat, and a first microphone installed near the front seat in the interior of the vehicle to detect noise near the front seat. A second microphone, a first correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone,
A first amplifier for amplifying the signal of the correction circuit of the above, and driving a speaker; a rear speaker mounted on a rear tray driven by an electric output from the first amplifier and radiating as an acoustic output into the vehicle cabin; A second correction circuit for appropriately correcting the phase and amplitude of the signal from the microphone of
To properly correct the phase and amplitude of the signal from the microphone
, A second amplifier for amplifying a signal obtained by adding the outputs from the second and third correction circuits and driving the speaker, and an electric output from the second amplifier, A front speaker disposed at a front door that radiates as sound output into the vehicle interior, wherein the sound pressure generated by the sound output from the rear speaker on the front seat side is canceled by the sound output from the front speaker. A vehicle interior noise reduction device, wherein a third correction circuit is set. 4. A first microphone installed near a front seat in a vehicle interior and detecting noise near the front seat, and a first microphone installed near a rear seat in the vehicle interior and detecting noise near the rear seat. A second microphone, a first correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone,
A first amplifier for amplifying a signal of the correction circuit of the above and driving a speaker; a front speaker mounted on a front door driven by an electric output from the first amplifier and radiating as an acoustic output into a vehicle interior; A second correction circuit for appropriately correcting the phase and amplitude of the signal from the second microphone; a third correction circuit for appropriately correcting the phase and amplitude of the signal from the first microphone; A second amplifier for amplifying a signal obtained by adding the outputs from the third and third correction circuits to drive a speaker, and is driven by the electric output from the second amplifier and radiates as an acoustic output into the vehicle interior. A rear speaker disposed on a rear tray, wherein the sound pressure generated by the sound output from the front speaker on the rear seat side is canceled by the sound output from the rear speaker. Interior noise reduction apparatus characterized by setting the positive circuit.