JP2014059375A - Active type muffler device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active type muffler device capable of applying a controller without considering crosstalk, and capable of effectively reducing noise for occupants.SOLUTION: Each pair of speakers 21 and 31 and error microphones 22 and 32 are respectively provided at portions positioned on the sides of headrests 51a and 52a out of the headrests 51a and 52a and sheet backs 51c and 52c of corresponding sheets 51 and 52, or above the sheets 51 and 52 among the top board of a vehicle. Respective speakers 21 and 31 are a planar electrostatic speaker, and movable bodies of the speakers 21 and 31 are formed by an elastomer. Respective controllers 23 and 33 independently perform adaptive control, and control the speakers 21 and 31 corresponding to the respective controllers 23 and 33.

Description

  The present invention relates to an active silencer that actively reduces noise.

  The apparatus described in Patent Document 1 detects acceleration as a reference signal by an acceleration sensor attached to a suspension, detects vehicle interior sound pressure as an error signal by each microphone attached in the vicinity of each passenger's ear, Road noise is silenced by outputting a control sound (secondary sound) by speakers attached to the doors on both sides of the door.

  Patent Document 2 describes that a plurality of speakers and a plurality of error microphones are installed in a vehicle interior, and the speakers are controlled based on a reference signal synchronized with engine rotation and an error signal detected by the error microphone. ing. Thereby, the noise in the passenger compartment accompanying the drive of the engine is reduced. Furthermore, in Patent Document 2, when a plurality of speakers and a plurality of error microphones are installed, crosstalk is taken into consideration by selecting a combination that has a good noise reduction effect from the plurality of combinations. It is described that the adaptive control is performed without the control.

  Patent Document 3 aims to mute at both ears of human beings, and an algorithm that does not consider the cross term can be applied by bringing the corresponding error microphone and the control sound source unit close to each other.

JP-A-3-203792 Utility Model Registration No. 2590783 Japanese Patent No. 4742226

  Here, as described in Patent Document 1, when the control sound is output by the speaker attached to each of the doors, the occupant not only outputs by the speaker closest to the seated seat but also other speakers. Affected by output. So-called crosstalk occurs. Therefore, in order to reduce the influence of the crosstalk, the controller needs to perform a complicated calculation process considering the crosstalk. Therefore, the cost of the controller becomes high.

  Patent Document 2 describes that application control is performed without considering crosstalk. Specifically, when installing a plurality of speakers and a plurality of error microphones, a single system that does not consider crosstalk is selected from a plurality of combinations by selecting a combination that has a good noise reduction effect in the passenger compartment. Is going to apply. However, each selected single system simply ignores the crosstalk and does not solve the problem of the crosstalk. That is, a certain error microphone is affected by not only the sound generated from the corresponding speaker but also the sound generated from another speaker.

  According to Patent Document 3, an error microphone and a control sound source unit are installed at the ear. For example, it is considered that earphones or headphones are used. When this device is applied for the purpose of reducing road noise, an occupant wears earphones or headphones, but this is not practical.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an active silencer that can apply a controller that does not consider crosstalk and can more effectively reduce noise to an occupant. To do.

  The active silencer according to this means is an active silencer that actively and independently reduces noise felt by each occupant seated in each seat in a vehicle interior, and is a reference signal detection that detects a reference signal. And a plurality of sets of control sound generating speakers, error microphones, and controllers associated with each seat.

  Each speaker is a planar electrostatic speaker, and the movable body of the speaker is formed of an elastomer. Each pair of speakers and error microphones includes a headrest of a corresponding seat, a headrest side of a seatback, or a vehicle. Each controller is provided on any one of the top positions of the top plate of the sheet, and each controller converts a reference signal detected by a reference signal detector and an error signal detected by an error microphone corresponding to each controller. Based on this, adaptive control is performed independently so that the error signal becomes small, and the speaker corresponding to each controller is controlled.

  Here, the mute target position is an occupant's ear. And according to the said means, a speaker and an error microphone are provided in the site | part located above the seat among the headrest side of a seat headrest and a seat back, or the top plate of a vehicle. That is, the speaker and the error microphone are close to the mute target position.

  A set of a speaker and an error microphone is provided on each of the plurality of sheets. Therefore, the distance between the same set of speakers and the error microphone is very short compared to the distance between the other set of error microphones of the speaker. Here, the sound pressure attenuates in inverse proportion to the square of the distance. Therefore, when the control sound generated by a certain set of speakers can be detected as a sufficient sound pressure by the same set of error microphones, it can be prevented from having a sound pressure that can be detected by another set of error microphones.

  That is, according to this means, there is no need to consider crosstalk. This means that the cross-talk is not ignored, and the silencing effect is almost the same regardless of whether or not the controller calculates in consideration of the cross-talk.

  Therefore, even if each controller performs control not considering crosstalk, that is, adaptive control independently based on the reference signal and each error signal, as in this means, a sufficient silencing effect can be exhibited.

  Here, according to this means, the speaker is arranged at the headrest or in the vicinity thereof. The reason why the speaker can be arranged in this position is that the speaker is a flat electrostatic speaker and the movable body of the speaker is made of an elastomer. In other words, since it is a flat speaker, it can be installed at the above site. Further, since the movable body of the speaker is formed of an elastomer, that is, a flexible material, no safety problem occurs even if it is installed on the head of the passenger. Further, since the occupant does not use headphones or the like, this can be realized.

  Preferably, the reference signal detector detects vibration or noise at a generation source of road noise generated in the vehicle interior as a reference signal, and the active silencer reduces road noise generated in the vehicle interior. Thereby, road noise can be silenced.

  When road noise is to be silenced, the reference signal detector is preferably disposed in the knuckle of the vehicle and detects vibration of the knuckle or noise in the knuckle as a reference signal. That is, the reference signal is the signal at the earliest position as the signal of the road noise generation source. Thereby, road noise can be reduced more effectively.

  Preferably, each set of speakers is arranged inside a headrest of a corresponding seat. A speaker can be installed at a position very close to the passenger's ear. Thereby, the high noise reduction effect in a passenger | crew's ear can be exhibited. In this case, each speaker is preferably provided within 8 cm from the ears of the passenger sitting on the corresponding seat.

  Preferably, each speaker is arranged inside the headrest of the corresponding seat so that the surface of the speaker faces the head of an occupant seated on the seat. When installed on the headrest, a control sound can be reliably generated with respect to the head of the occupant by doing as described above. Therefore, the high noise reduction effect in the passenger | crew's ear can be exhibited.

  When each pair of speakers is arranged inside the headrest, the error microphone may be arranged inside the same headrest as the corresponding speaker. That is, the same set of speakers and error microphones are arranged inside the headrest. As a result, the distance between the same pair of speakers and the error microphone can be made extremely short. Therefore, the influence of crosstalk can be reduced more reliably.

  Preferably, each set of speakers is arranged in a portion of the top plate of the vehicle located above the corresponding seat. A speaker can be installed at a position relatively close to the passenger's ear. Thereby, the sufficient noise reduction effect in a passenger | crew's ear can be exhibited.

  In this case, preferably, each speaker is arranged on the top plate of the vehicle so that the surface of the speaker faces the head of the passenger sitting on the seat. Thereby, a control sound can be reliably generated with respect to the head of the passenger. Each speaker may be provided within 30 cm from the ears of the passenger sitting on the corresponding seat.

  Preferably, each controller is formed separately from the corresponding speaker and error microphone, and is positioned above the seat on the headrest side of the corresponding seat, the headrest side of the seatback, and the top plate of the vehicle. It is provided in each part other than the part. By avoiding placing the controller near the head of the occupant, the safety for the occupant and the degree of freedom of installation can be increased. However, if the controller can be reduced in size, there is no problem even if the controller is arranged near the head of the passenger.

  Preferably, the movable body of the speaker includes first and second electrostatic electrode bodies, a first electrostatic electrode body, and a first electrostatic electrode body each having a dielectric layer formed of an elastomer between opposing electrode pairs. An intermediate formed by an elastomer or an elastomer foam is provided between the two electrostatic electrode bodies. As a result, the speaker can be planar, and the planar movable body can be formed of a flexible material. Therefore, even if the speaker is installed in the vicinity of the head of the occupant, no safety problem occurs.

It is a figure which shows arrangement | positioning in the vehicle of the active silencer of 1st embodiment of this invention. It is a figure which shows arrangement | positioning of the speaker and error microphone in the sheet | seat of FIG. It is sectional drawing which shows the structure of the speaker shown in FIG. FIG. 4 is a front view of the speaker shown in FIG. 3. FIG. 4 is a cross-sectional view showing a state where the voltage applied to the AC power supply is positive in the speaker shown in FIG. 3. FIG. 4 is a cross-sectional view showing a state where the voltage applied to the AC power supply is a negative electrode in the speaker shown in FIG. 3. It is a control block diagram of the controller shown in FIGS. It is a figure which shows arrangement | positioning of a speaker and an error microphone in the active silencer of 2nd embodiment of this invention. It is a figure which shows arrangement | positioning of a speaker and an error microphone in the active silencer of 3rd embodiment of this invention. In the active silencer of 4th embodiment of this invention, the control block diagram of a controller is shown.

<First embodiment>
The active silencer of the first embodiment will be described. The active silencer actively reduces the noise felt by each occupant seated on each seat independently. In particular, the device according to the present embodiment is exemplified as a case of reducing road noise generated in the vehicle interior.

(Arrangement of each part of active silencer in vehicle)
As shown in FIG. 1, the active silencer includes four reference sensors 11 to 14 and two sets of system units 20 and 30. Each of the reference sensors 11 to 14 (corresponding to the “reference signal detector” of the present invention) detects vibration or noise at a road noise source. Each reference sensor 11-14 applies, for example, an acceleration sensor that detects vibration or a microphone that detects noise. Each reference sensor 11-14 is attached to the knuckle 41-44 which comprises the suspension apparatus which supports each wheel 31-34, and detects the vibration or noise of each knuckle 41-44 as a reference signal. Here, the vibration or noise of the knuckles 41 to 44 is a signal at the earliest position as a road noise generation source signal.

  Each system unit 20, 30 is provided on each sheet. Here, the system units 20 and 30 are provided in the front seats 51 and 52, respectively. The system unit may be provided in the rear seats 53 and 54.

  Each of the system units 20 and 30 includes control sound generating speakers 21 and 31, error microphones 22 and 32, and controllers 23 and 33, respectively. Each system unit 20, 30 reduces noise caused by the reference signal in each error microphone 22, 32 by independent adaptive control. The so-called system units 20 and 30 constitute a single system.

  Each speaker 21 and 31 is a planar electrostatic speaker. The speakers 21 and 31 and the error microphones 22 and 32 are disposed inside the headrests 51a and 52a of the corresponding sheets 51 and 52, respectively. The controllers 23 and 33 that perform adaptive control are formed separately from the speakers 21 and 31 and the error microphones 22 and 32, and are disposed below the seating surfaces 51 b and 52 b of the corresponding seats 51 and 52. In addition, you may arrange | position each controller 23 and 33 in the center of the width direction of a vehicle, for example.

  Here, the signal flow in each of the controllers 23 and 33 is as shown by the broken lines in FIG. Signals are input to the first controller 23 from all the reference sensors 11 to 14 and the first error microphone 22. The first controller 23 outputs a signal to the first speaker 21. Signals are input from all the reference sensors 11 to 14 and the second error microphone 32 to the second controller 33. The second controller 33 outputs a signal to the second speaker 31. That is, the first and second controllers 23 and 33 respectively control the corresponding speakers 21 and 31 independently. Each system unit 20, 30 constitutes a single system that does not consider crosstalk. Note that the two controllers 23 and 33 are independent as functions, and may be arranged in the same housing, for example.

(Speaker and error microphone placement)
Next, the details of the arrangement of the speaker 21 and the error microphone 22 in the seat 51 will be described with reference to FIG. Since the arrangement of the speaker 31 and the error microphone 32 in the seat 52 is the same, the description thereof is omitted.

  As shown in FIG. 2, the speaker 21 is disposed inside the headrest 51a. Here, the headrest 51a includes a resinous core material 51a1, a cushion material such as urethane foam (not shown), and a skin material 51a2 covering these. The cushion material has a role of improving the sitting comfort and mitigating the impact with respect to the head of the occupant. The speaker 21 is attached to the core member 51a1 and is disposed closer to the occupant's head (front of the vehicle) than the core member 51a1. The speaker 21 is disposed so as to be sandwiched between the core material 51a1 and the cushion material, for example.

  And the speaker 21 is arrange | positioned inside the headrest 51a so that the surface of the speaker 21 may oppose the passenger | crew's head seated on a sheet | seat. That is, the speaker 21 generates a control sound directly toward the head of the passenger. At this time, the speaker 21 sets the distance L from the passenger's ear within 8 cm. In FIG. 2, the occupant's head and ears are indicated by a two-dot chain line.

  Further, the error microphone 22 is arranged inside a headrest 51 a similar to the speaker 21. Similar to the speaker 21, the error microphone 22 is attached to the core material 51a1 of the headrest 51a. That is, the error microphone 22 detects the sound at the position where it is placed.

(Structure of speaker and drive circuit)
Next, the structure of the speaker 21 and the drive circuit will be described with reference to FIGS. The speaker 31 in the seat 52 is the same and will not be described. The speaker 21 is a planar electrostatic speaker.

  As shown in FIGS. 3 and 4, the speaker 21 includes first and second rectangular frames 21 b and 21 c and a rectangular movable body 21 a sandwiched between the rectangular frames 21 b and 21 c. The rectangular frames 21b and 21c are fixed to the core material 51a1. The movable body 21a of the speaker 21 has flexibility as a whole, and is formed of an elastomer, that is, a flexible material. Hereinafter, the movable body 21a will be described in detail.

  The movable body 21 a includes first and second electrostatic electrode bodies 110 and 120 and an intermediate body 130. Each of the electrostatic electrode bodies 110 and 120 includes a rectangular dielectric layer 113 formed of an elastomer between the opposed rectangular electrode pairs 111, 112, 121, and 122 and the opposed electrode pairs 111,. , 123. The electrode pairs 111, 112, 121, and 122 are formed of a flexible material such as an elastomer. Here, the thicknesses of the electrode pairs 111,... And the dielectric layers 113, 123 are formed to be substantially uniform. In addition, each electrostatic electrode body 110, 120 is covered with an insulating layer (not shown) on both surfaces.

  The intermediate body 130 is formed of an elastomer or an elastomer foam, and is sandwiched between the first electrostatic electrode body 110 and the second electrostatic electrode body 120. The intermediate body 130 is formed so that the thickness at the center becomes thicker and becomes thinner toward the periphery. Accordingly, the peripheral edge of the movable body 21a is thin, and the peripheral edge is sandwiched between the rectangular frames 21b and 21c. The center of the surface of the movable body 21a is raised on each of both surfaces.

  The driving circuit of the speaker 21 includes an AC power source 141, a positive side circuit 142, a negative side circuit 143, and a ground circuit 144. The positive-side circuit 142 is a circuit that is connected so that current flows from the AC power source 141 to the outer electrode 111 of the first electrostatic electrode body 110 when the voltage of the AC power source 141 is positive. The negative electrode side circuit 143 is a circuit that is connected so that current flows from the outer electrode 121 of the second electrostatic electrode body 120 to the AC power source 141 when the voltage of the AC power source 141 is negative. The ground circuit 144 is connected to the ground terminal of the AC power supply 141 and is electrically connected to the inner electrode 112 of the first electrostatic electrode body 110 and the inner electrode 122 of the second electrostatic electrode body 120. The

  The operation of the speaker 21 will be described with reference to FIGS. As shown in FIG. 5, when the voltage of the AC power supply 141 is positive, a current flows through the positive circuit 142 and a potential difference is generated between the electrodes 111 and 112 of the first electrostatic electrode body 110. Then, a force that reduces the distance between the electrodes 111 and 112 of the first electrostatic electrode body 110 acts, the dielectric layer 113 becomes thin, and the first electrostatic electrode body 110 The electrodes 111 and 112 are deformed so as to extend. At this time, the intermediate body 130 follows the deformation of the first and second electrostatic electrode bodies 110 and 120.

  On the other hand, as shown in FIG. 6, when the voltage of the AC power supply 141 is negative, a current flows through the negative circuit 143 and a potential difference is generated between the electrodes 121 and 122 of the second electrostatic electrode body 120. Then, a force that reduces the separation distance between the electrodes 121 and 122 of the second electrostatic electrode body 120 acts, the dielectric layer 123 becomes thin, and the second electrostatic electrode body 120 The electrodes 121 and 122 are deformed so as to extend.

  On the other hand, as shown in FIG. 6, when the voltage of the AC power supply 141 is negative, no current flows through the positive circuit 142, so that the potential difference between the electrodes 111 and 112 of the first electrostatic electrode body 110 is Get smaller. Then, a force that returns the separation distance between the electrodes 111 and 112 of the first electrostatic electrode body 110 acts, and the thinly deformed dielectric layer 113 is thickened and stretched. The electrodes 111 and 112 of one electrostatic electrode body 110 are deformed so as to shrink. At this time, the intermediate body 130 follows the deformation of the first and second electrostatic electrode bodies 110 and 120.

  The movable body 21a vibrates by repeating the state of FIG. 5 and the state of FIG. This vibration generates a control sound. By configuring the speaker 21 as described above, the speaker 21 can be planar. Furthermore, as described above, since the movable body 21a is formed of an elastomer or a foam, it has flexibility. Therefore, even if the speaker 21 is installed in the vicinity of the passenger's head, no safety problem occurs.

(Adaptive control by controller)
Next, adaptive control by the controllers 23 and 33 will be described with reference to FIG. The first controller 23 performs adaptive control based on the reference signals r1 to r4 detected by the reference sensors 11 to 14 and the error signal e1 detected by the first error microphone 22. In this embodiment, the Filtered-X LMS algorithm is applied as adaptive control.

  That is, the first controller 23 calculates the output values u1 to u4 by each adaptive control. In each adaptive control, the output values u1 to u4 are calculated so as to reduce the error signal e1. Here, in the case of adaptive control by the Filtered-X LMS algorithm, identification values G1h to G4h of transfer characteristics in each secondary path are used in advance. In the drawings, “^” attached to a symbol is called a hat and means an identification value. However, for the convenience of description, “^” is described as “h” in the text.

Further, the first controller 23 calculates a control signal usum1 obtained by adding all the output values u1 to _u4 . This control signal _usum1 becomes a control signal for driving the speaker 21. Since the speaker 21 is driven based on the control signal _usum1 , the influence of the reference signals r1 to r4 in the error signal e1 is reduced.

  The second controller 33 adapts the Filtered-X LMS algorithm based on the reference signals r1 to r4 detected by the reference sensors 11 to 14 and the error signal e2 detected by the second error microphone 32. Take control. That is, the second controller 33 calculates the output values u5 to u8 by each adaptive control. Here, in the case of adaptive control by the Filtered-X LMS algorithm, identification values G5h to G8h of transfer characteristics in each secondary path are used in advance.

Further, the second controller 33 calculates a control signal u _sum2 obtained by adding all the output values U5～u8. This control signal _usum2 is a control signal for driving the speaker 31. By the speaker 31 is driven based on the control signal u _sum2, influence caused by the reference signal r1~r4 of the error signal e2 is smaller. That is, the road noise felt by each occupant can be silenced.

  Here, the first controller 23 does not consider the error signal e2 detected by the second error microphone 32. Further, the second controller 33 does not consider the error signal e1 detected by the first error microphone 22. That is, the controllers 23 and 33 are independently controlled and do not consider crosstalk.

  According to the active silencer of this embodiment, the speakers 21 and 31 and the error microphones 22 and 32 are provided inside the headrests 51a and 52a of the respective sheets 51 and 52 as the same member. That is, the speakers 21 and 31 and the error microphones 22 and 32 are very close to the occupant's ears, which are the positions to be silenced.

  Therefore, the distance between the speakers 21 and 31 and the error microphones 22 and 32 of the same set can be extremely shortened. Furthermore, the distance between the speaker 21 and the error microphone 22 in the same group is very short compared to the distance between the speaker 21 and the error microphone 32 in another group. The reverse is also true.

  Here, the sound pressure attenuates in inverse proportion to the square of the distance. Therefore, when the control sound generated by the speaker 21 can be detected as a sufficient sound pressure by the same set of error microphones 22, it can be prevented from having a sound pressure that can be detected by another set of error microphones 32. The reverse is also true. That is, it is not necessary to consider crosstalk by arranging the speakers 21 and 31 and the error microphones 22 and 32 as described above. This means that the crosstalk is not ignored, and the silencing effect is almost the same regardless of whether the controllers 23 and 33 perform the calculation in consideration of the crosstalk or not.

  Therefore, even if the controllers 23 and 33 perform control that does not consider crosstalk, that is, perform adaptive control independently based on the reference signals r1 to r4 and the error signals e1 and e2, a sufficient silencing effect is exhibited. it can.

  Here, the speakers 21 and 31 are arranged on the headrests 51a and 52a. The reason why the speaker 21 and 31 can be arranged in this position is that the speakers 21 and 31 are flat electrostatic speakers and the movable body 21a of the speaker 21 is formed of an elastomer. That is, since the planar speakers 21 and 31 are installed, the speaker can be installed at the above-mentioned site. Furthermore, even if it installs in the passenger | crew's head by forming the movable body of the speakers 21 and 31 with an elastomer, ie, a flexible material, no problem arises on safety. Further, since the occupant does not use headphones or the like, this can be realized.

  The controllers 23 and 33 are formed separately from the corresponding speakers 21 and 31 and the error microphones 22 and 32, and are disposed below the seating surfaces 51b and 52b of the corresponding seats 51 and 52, respectively. By avoiding the placement of the controllers 23 and 33 near the head of the occupant, safety for the occupant and freedom of installation can be increased. If the controllers 23 and 33 can be reduced in size, there is no problem even if the controllers 23 and 33 are arranged in the vicinity of the occupant's head.

<Second embodiment>
The active silencer of the second embodiment will be described with reference to FIG. In the present embodiment, the installation positions of the speakers 21 and 31 are different from those of the above embodiment.

  As shown in FIG. 8, the speaker 21 constituting the first system unit 20 is disposed inside the seat back 51 c of the corresponding seat 51. In particular, the speaker 21 and the error microphone 22 are arranged on the headrest 51a side of the seat back 51c. Moreover, the error microphone 22 is arranged inside the headrest 51a, as in the first embodiment.

  Furthermore, the speaker 21 is disposed in the seat back 51 c of the corresponding seat 51 so that the surface of the speaker 21 faces the head of the passenger sitting on the seat 51. Thereby, a control sound can be reliably generated with respect to the head of the passenger. Therefore, the high noise reduction effect in the passenger | crew's ear can be exhibited.

  Further, although not shown, the speaker 31 constituting the second system unit 30 is disposed inside the seat back 52c (shown in FIG. 1) of the corresponding seat 52. The details are the same as those of the first system unit 20. According to the present embodiment, there are substantially the same effects as the first embodiment. The error microphones 22 and 32 may be disposed inside the seat backs 51c and 52c of the corresponding seats 51 and 52, respectively.

<Third embodiment>
The active silencer of the third embodiment will be described with reference to FIG. In the present embodiment, the installation positions of the speakers 21 and 31 are different from those of the above embodiment.

  As shown in FIG. 9, the speaker 21 constituting the first system unit 20 is disposed in a portion of the top plate 70 of the vehicle that is located above the corresponding seat 51. Furthermore, the speaker 21 is disposed so that the surface of the speaker 21 faces the head of an occupant seated on the seat 51. Moreover, the error microphone 22 is arranged inside the headrest 51a, as in the first embodiment. Thereby, a control sound can be reliably generated with respect to the head of the passenger. Therefore, the high noise reduction effect in the passenger | crew's ear can be exhibited. Here, the speaker 21 is provided with a distance L from the ears of the passenger sitting on the corresponding seat 51 within 30 cm.

  Moreover, the speaker 31 which comprises the 2nd system unit 30 is arrange | positioned above the corresponding sheet | seat 52 (shown in FIG. 1) among the top plates 70 of a vehicle similarly to the above. The details are the same as those of the first system unit 20. According to the present embodiment, there are substantially the same effects as the first embodiment. The error microphones 22 and 32 may be arranged above the corresponding seats 51 and 52 on the top plate 70 of the vehicle.

<Fourth embodiment>
An active silencer according to a fourth embodiment will be described with reference to FIG. In the present embodiment, the application control of the controllers 23 and 33 is different from the first embodiment. In the present embodiment, the controllers 23 and 33 apply a direct adaptive algorithm (DAA) instead of the Filtered-X LMS algorithm. For example, the direct LMS algorithm is applied.

  As shown in FIG. 10, the first controller 23 performs adaptive control based on the reference signals r1 to r4, the first error signal e1, and the output values u1 to u4 of the respective adaptive filters. The second controller 33 performs adaptive control based on the reference signals r1 to r4, the second error signal e2, and the output values u5 to u8 of the respective adaptive filters. By applying the direct method, the identification of the secondary path G becomes unnecessary. According to the present embodiment, there are substantially the same effects as the first embodiment.

  The RLS algorithm, the FDA algorithm, the direct method RLS algorithm, and the direct method FDA algorithm can be applied as other adaptive control of the Filtered-X LMS algorithm and the direct method LMS algorithm described in the above embodiment.

11-14: Reference sensor 41-44: Knuckle 21, 31: Speaker 21a: Movable body 22, 32: Error microphone 23, 33: Controller 51-54: Seat 51a, 52a: Headrest 51c , 52c: seat back, 70: top plate, 110: first electrostatic electrode body, 120: second electrostatic electrode body, 111, 112, 121, 122: electrode pair, 113, 123: dielectric layer 130: Intermediate

Claims (12)

An active silencer that actively and independently reduces noise felt by each occupant seated in each seat in a vehicle interior,
A reference signal detector for detecting the reference signal;
A plurality of sets of control sound generating speakers, error microphones, and controllers associated with each of the sheets;
With
Each speaker is a flat electrostatic speaker, and the movable body of the speaker is formed of an elastomer,
Each set of the speaker and the error microphone is provided at either the headrest of the corresponding seat, the headrest side of the seatback, or the portion of the top plate of the vehicle located above the seat. And
Each of the controllers can independently reduce the error signal based on the reference signal detected by the reference signal detector and the error signal detected by the error microphone corresponding to the controller. An active silencer that performs adaptive control and controls the speaker corresponding to each controller. The reference signal detector detects vibration or noise at a road noise source generated in the vehicle room as the reference signal,
The active silencer according to claim 1, wherein the active silencer reduces road noise generated in a room of the vehicle.   The active silencer according to claim 2, wherein the reference signal detector is disposed on a knuckle of the vehicle and detects vibration of the knuckle or noise in the knuckle as the reference signal.   4. The active silencer according to claim 1, wherein each pair of the speakers is disposed inside the headrest of the corresponding seat. 5.   5. The active silencer according to claim 4, wherein each speaker is disposed inside the headrest of the corresponding seat so that a surface of the speaker faces a head of an occupant seated on the seat.   6. The active silencer according to claim 4, wherein each speaker is provided within 8 cm from an ear of a passenger sitting on the corresponding seat.   Each of the error microphones is an active silencer according to any one of claims 4 to 6, which is disposed inside the headrest of the corresponding seat.   The active silencer according to any one of claims 1 to 3, wherein the speakers of each set are disposed in a portion of the top plate of the vehicle positioned above the corresponding seat.   9. The active silencer according to claim 8, wherein each of the speakers is disposed on a top plate of the vehicle so that a surface of the speaker faces a head of an occupant seated on the seat.   10. The active silencer according to claim 8, wherein each speaker is provided within 30 cm from an ear of a passenger sitting on the corresponding seat.   Each of the controllers is formed separately from the corresponding speaker and the error microphone, and the corresponding headrest of the seat, the headrest side of the seatback, and the seat of the top plate of the vehicle. The active silencer according to any one of claims 1 to 10, which is provided in a portion other than the portion located above. The movable body of the speaker includes first and second electrostatic electrode bodies each including a dielectric layer formed of an elastomer between opposing electrode pairs, the first electrostatic electrode body, and the second electrostatic electrode body. An active silencer according to any one of claims 1 to 11, further comprising an intermediate formed by an elastomer or an elastomer foam between the electrostatic electrode body.