EP1094444A1 - Aktive Vorrichtung zur Abschwächung der Schallintensität - Google Patents

Aktive Vorrichtung zur Abschwächung der Schallintensität Download PDF

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Publication number
EP1094444A1
EP1094444A1 EP00420204A EP00420204A EP1094444A1 EP 1094444 A1 EP1094444 A1 EP 1094444A1 EP 00420204 A EP00420204 A EP 00420204A EP 00420204 A EP00420204 A EP 00420204A EP 1094444 A1 EP1094444 A1 EP 1094444A1
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EP
European Patent Office
Prior art keywords
sources
noise
waves
acoustic
counter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP00420204A
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English (en)
French (fr)
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EP1094444B1 (de
Inventor
Lionel Gaudriot
Jacques Martinat
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Comptoir de la Technologie
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Comptoir de la Technologie
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Publication of EP1094444A1 publication Critical patent/EP1094444A1/de
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Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01F—ADDITIONAL WORK, SUCH AS EQUIPPING ROADS OR THE CONSTRUCTION OF PLATFORMS, HELICOPTER LANDING STAGES, SIGNS, SNOW FENCES, OR THE LIKE
    • E01F8/00—Arrangements for absorbing or reflecting air-transmitted noise from road or railway traffic
    • E01F8/0094—Arrangements for absorbing or reflecting air-transmitted noise from road or railway traffic constructions for generation of phase shifting
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/12—Rooms, e.g. ANC inside a room, office, concert hall or automobile cabin
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/124—Traffic
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3212—Actuator details, e.g. composition or microstructure
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3215—Arrays, e.g. for beamforming

Definitions

  • the invention relates to the field of acoustics. More specifically, it targets fixed devices for reducing noise generated by mobile sources, such as especially means of transport in general, and airplanes or land transport in particular.
  • the invention constitutes an improvement of the device described in the patent EP 0 787 340 to the Applicant.
  • the Applicant described in the aforementioned patent a device for attenuation of the sound intensity operating on the principle of the emission of a counter-noise wave generated from information from sensors, and emitted by electro-acoustic sources arranged in such a way that the counter-noise waves combine with the noise waves they admit as an envelope.
  • the different sources against noise are associated by sub-assemblies mounted on vertical masts, that is to say in a direction substantially perpendicular to the direction of average incidence noise waves.
  • the different masts are arranged around the area to be protect, and preferably at the periphery of the area to be protected.
  • the spacing of the masts as described in this document does not not sufficiently attenuate the sound waves having a frequency relatively large, and in particular greater than 500 Hz (Hertz).
  • a problem which the invention proposes to solve is that of attenuation effective sound waves in a range up to kiloHertz, or even up to 2 kHz (kiloHertz).
  • This device is characterized in that the electro-acoustic sources are arranged on a continuous surface, and according to a regular mesh.
  • the invention consists in associating the different sources of such so that they constitute a sufficiently tight mesh to allow a attenuation of high frequency waves, i.e. in application to treatment sound waves on the order of a kiloHertz.
  • the sources are spaced from each other areas with a distance between one and two meters.
  • the incident waves are no longer only reflected by the screen, but also diffracted upstream and downstream of the screen, with for effect of inducing a pressure level twice the level of the incident wave, which makes then said screen not inoperative, but disruptive.
  • the different sources are arranged according to surfaces which can be produced by a trellis which is itself raised, arranged above the area to be covered or above the buildings adjoining it.
  • continuous surface is meant a surface which has geometric regularity such that all sources can be considered, with respect to a noise wave, as equivalent in their contribution to mitigation, to the effect near their orientation.
  • Such surfaces can be flat, or for example belong to the family quadrics, and in particular cylinders.
  • the device according to the invention comprises several sets of electro-acoustic sources arranged in several surfaces offset relative to each other by translation normal to their surface, of so as to form complex, multi-layered electroacoustic sources, which allows to increase their transverse spacing, with equal bandwidth.
  • several devices can be combined so that these devices are juxtaposed next to each other in the space of the area to protect, to cover a particular geometry area, such as a intersection of streets.
  • These devices can be combined, in continuity with surfaces of the same nature constituting passive screens, in particular glazed structures, for architectural and functional reasons.
  • the different screens are controlled by a microphonic capture system located upstream near the screen.
  • This noise wave capture system has the ability to separate and characterize these waves respectively in direction and in signal, so as to allow the counter-noise sources to counteract them additively.
  • the control means are able, using the appropriate algorithms, to extract the common reference signal as well as the amplitude and delay parameters specific to each echo signal, from a set or base of sensors microphones placed upstream of the screens.
  • the minimum number of sensors to be used in the microphone base is at least equal to the number of signals to be discriminated, but practically greater for get rid of the effect of parasitic noise of near origin.
  • the sources of noise are multiple and independent, such as for noise generated by means of transport on land, such as vehicles, cars or wagons.
  • the number of eigen signals, independent sources is greater than the ten.
  • the microphone bases can be arranged along the roadway or railway track so as to selectively acquire, by proximity, the various reference signals specific to independent sources, such as wheel sets, bogies, and air boundary layers.
  • the correlation coefficient of the counter-noise signal to the noise signal is 0.995, value which reflects the very great similarity to be obtained between noise signals, with large bandaged.
  • Figure 1 is a summary perspective view of a residential area equipped with several screens according to the invention.
  • Figure 2 is a summary perspective representation of a house located near a traffic lane, and fitted with screens in accordance with the invention.
  • Figure 3 is a schematic representation of a screen according to the invention as well as different control blocks for each of the active elements of the screen.
  • Figure 4 is a schematic representation of an electro-acoustic source monolayer used in a screen according to the invention, in a mesh of the network.
  • Figure 5 is a schematic view illustrating a two-layer association of sources. In these last two figures, we have drawn the lines tangent to the main axis most along acoustic particulate hodographs.
  • Figure 6 shows a window frame protected by a plurality of electroacoustic sources arranged in accordance with the invention.
  • Figure 7 is a schematic perspective view of a set of sources associated in three parallel planes.
  • the invention relates to an improvement of the device noise reduction as described in patent EP 0 787 340.
  • Such a device includes a number of surfaces grouping sources electroacoustics. According to a characteristic of the invention, these surfaces are continuous from so as to cover an area of up to several hundred meters square, these surfaces are arranged at altitudes of the order of 10 to 15 m, or even more, above places to protect.
  • These surfaces are produced for example by trellis of tubes or cables to the intersection of which the sources of counter-noise are fixed.
  • the area to be protected may include a number flat screens A, B, C, D, intended to ensure this protection.
  • the screens A, B, C are arranged above the street to protect R1 while the screen D is placed high, across the street R1, and is intended to block the guided waves, by multiple reflections on the facades along the street.
  • the device makes it possible to protect part of the metropolitan area adjacent to an airport, with regard to aircraft noise on takeoff and landing along a trajectory substantially parallel to the street R1 illustrated in FIG. 1, at a horizontal distance of the order of half a kilometer.
  • screens A and C are placed immediately above the building facades, in front of the area to be protected. They are arranged in such a way as to be inclined to the vertical.
  • Screen B is placed across a street perpendicular R2 to the street main R1 parallel to the path of the aircraft. This screen B closes the gap offered to aircraft noise, when this one overlooks this perpendicular street R2.
  • Screen D is placed in the same way, across street R1 so to reflect the noise which reaches the area to be protected in a guided way, by reflection preliminary and multiple along the facades in the street R1.
  • Screens B and D are also tilted to improve the efficiency of the device mitigation.
  • the device is intended to protect an isolated dwelling (10) located at the edge of a motorway (11) with regard to traffic noise.
  • the device consists of a cylindrical screen (12) adapted to the protection of the main facade of the house (10) exposed to noise.
  • the signals generated by the microphones (15) are routed to the control of the screen (12) by an appropriate means and in particular by wire connection (not shown).
  • the screens consist of pylons (20-22) of form suitable supporting panels (24) of regular lattice with triangular, square meshes or preferably hexagonal, in the center of which are fixed the sources (25) of noise counter.
  • These sources can be single-layers, or preferably multi-layers, that is to say made up of the association of several speakers offset one compared to the others, and according to the normal to the reference surface.
  • the block (41) for characterizing noise waves makes it possible to determine the main characteristics of the direct incident waves reflected by the ground and various obstacles.
  • This characterization block (41) determines the respective directions of the normals to these waves, the acoustic signals specific to each of them as well as their positions relative in time.
  • the delay of each of these signals with respect to the direct wave signal is determined with respect to a single reference point Oi, called “reference point of the microphone base ", generally located at its barycenter.
  • the counter-noise source control block (42) provides linear filtering identical for each of the characteristic signals of the noise waves coming from the blocks (41) of the aforementioned characterization.
  • the purpose of this filtering is to equalize the group times of the electroacoustic sources. over the range of the screen action frequency band.
  • Each of the filtered signals is then routed, for example by multiplexing, over a common bus (44) to the integrated control blocks (43) of the noise reduction sources.
  • the sources of noise control around the edges of the screens are subject to orders similar to the whole, but adjusted in a specific way in level and time to regularize the side effects.
  • the non-linear distortion rate must be less than 2.10 -3 , at the maximum level delivered.
  • the effect of the physical parameters of the environment such as temperature, atmospheric pressure, humidity rate, are compensated so as not to affect the linearity of the response. beyond the rate of 2.10 -3 required.
  • the precision and the extraction of the signals must be of the order of 10 -3 , which implies in particular a rate of crosstalk less than this value, and thus fixes the overall performance of the algorithms designed to ensure, in real time, this discrimination.
  • the correlation coefficient of the counter-noise signal to the noise signal was greater than 0.995, which implies a maximum phase shift between their spectral components of 6 °, or 1/60 th of the period.
  • the temporal resolution of the signals must typically be better than 17 micro seconds for the frequency of one kiloHertz.
  • the cadence of the clock which fixes the timing step of the signals in the speaker control blocks will be greater than 60 kiloHertz.
  • this temporal resolution corresponds to a resolution in position geometric of the sixtieth of the maximum wavelength, i.e. 5 mm for a maximum frequency of 1 kiloHertz.
  • This value corresponds to the rigidity requirement of the support structure, which links the microphone base on the noise reduction sources panel.
  • the action of the counter-noise sources with respect to this front consists, for each source, in interacting with this front at the exact moment of its passage, and in such a way that this front does not propagate beyond the source, in direction of the downstream area to be protected.
  • the sources of counter-noise therefore simultaneously create boundary conditions adapted to reflect or absorb the incident wavefront.
  • Sources of noise control thus constitute screens realizing, in acoustic terms, boundary conditions particular.
  • the pressure is indeed zero on the screen surface, and the acoustic load is therefore zero at the source.
  • This field is spatially organized in a network, by tubular cells which repeat themselves periodically according to the meshes of the screen, as soon as these meshes are sufficient numerous, so that the organization of the interference field is practically invariant from one stitch to another.
  • the "current lines” allow you to define acoustic current which converges on the active surface of the counter-noise source, that is to say the diaphragm of the speaker (25).
  • These tubes constitute as many fictitious waveguides inside which is established the interference field.
  • the difference of guided wave walk increases as the tubes move away from the axis of revolution to become practically equal to the diameter "a" of the cell.
  • the cut-off frequency f o is therefore close to c / a , as stated above.
  • the incident traveling progressive wave guided in the extreme tube can no longer be controlled by the noise reduction source, and crosses the screen giving birth of refracted, oblique waves, which obstruct the protective role conferred on the screen.
  • the sources can be advantageously arranged in sub-assemblies according to screens parallel to one another others, and the operation is then illustrated in FIG. 5.
  • the operation of multi-layer sources makes it possible to increase the cut-off frequency of the system for a given dimension of the mesh of the network. More precisely, and according to the diagram illustrated in FIG. 5, the different sources (27, 28) of the same mesh are controlled, with a determined phase offset, to act on the end tube (51) so as to avoid it to escape above the frequency f 0 , continuing to keep the "current lines" channeled towards the source of the appropriate layer.
  • a series of secondary sources (28), ordered with the desired phases and modules makes it possible to capture and reflect the acoustic flow of the incident wave, for the current lines which escape the primary source (27), in respecting the interference structure of the sound field, close to the loudspeaker, such as previously described.
  • FIG. 5 represents a single secondary source.
  • this running delay is compensated by the control device, which supplies this second source (28) with a signal delayed substantially by d + a / c , this value being able to be adjusted with more precision: so as to ensure strictly the orthogonality of the source field to the oblique modes of the network.
  • the cutoff frequency is thus brought to twice the initial frequency, itself close to c / a.
  • the flow rates of the sources are adjusted in proportion to the surfaces of the controlled current tubes.
  • the sources as represented in FIG. 5, by axis loudspeakers can be advantageously carried out by contiguous sets of sources smaller dimensions, properly assembled and ordered with delays appropriate to ensure the best regularity in the acoustic flow field.
  • the device according to the invention provides a noise attenuation in a frequency band covering the majority of the spectrum noise waves from means of transport such as airplanes or railways.
  • the operation of the screen described is an active reflector operation with respect to against incident noise waves, it is nevertheless possible to envisage an operation as a perfect absorber of these waves insofar as the reflected waves could present, in certain situations, a harmful effect with respect to the surrounding site.
  • the downstream source is acoustically discharged and it is the upstream source which absorbs the power of noise.
  • the active reflective acoustic screens described can be combined in their operation on contiguous passive screens.
  • These passive screens can be constituted by pre-existing built surfaces (roofs and facades of buildings according to the figure 1). They can also be installed for acoustic reasons, in complementarity of active screens, and produced using architectural techniques adapted, in particular using glazed surfaces of suitable thickness, according to arguments of use or aesthetics, specific to the development of particular sites.
  • Such passive screens then cause a reflection of the dual type of the type described.
  • active screens namely that acoustically "hard”, they create the conditions for limits approaching the cancellation of the normal acoustic speed, and the doubling of the sound pressure on their surface.
  • sources with variation control are used. pressure. These are sources that we do not have a priori, the various types of speakers on the contrary approach sources of flow variation, and their delay response makes their control in pressure variation illusory.
  • Such sources are produced by association, by pair of sources of variation of opposite flow rates, mounted back to back, constituting an acoustic dipole.
  • Such sources are in particular to be used for producing active screens on openings in front of buildings, windows or bays, so as to ensure the condition reflection in an "open window” situation, thus preventing external noise from entering the interior of dwellings.
  • multiple sources of bipolar type are produced, for example four sources (26) at the four corners of the doorway, according to the assembly described in FIG. 6.
  • Such multiple sources can be realized, as illustrated in FIG. 7, by the association of several elementary sources (27) deposited in parallel planes.
  • Each elementary source (27) is a bipolar source having two speaking faces in opposition.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Architecture (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Fittings On The Vehicle Exterior For Carrying Loads, And Devices For Holding Or Mounting Articles (AREA)
  • Electrophonic Musical Instruments (AREA)
  • Amplifiers (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
EP00420204A 1999-10-18 2000-10-10 Aktive Vorrichtung zur Abschwächung der Schallintensität Expired - Lifetime EP1094444B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9913164 1999-10-18
FR9913164A FR2799873B1 (fr) 1999-10-18 1999-10-18 Dispositif actif d'attenuation de l'intensite sonore

Publications (2)

Publication Number Publication Date
EP1094444A1 true EP1094444A1 (de) 2001-04-25
EP1094444B1 EP1094444B1 (de) 2004-11-17

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EP00420204A Expired - Lifetime EP1094444B1 (de) 1999-10-18 2000-10-10 Aktive Vorrichtung zur Abschwächung der Schallintensität

Country Status (5)

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US (1) US6463156B1 (de)
EP (1) EP1094444B1 (de)
AT (1) ATE282878T1 (de)
DE (1) DE60015902T2 (de)
FR (1) FR2799873B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8526654B2 (en) 2009-05-20 2013-09-03 Didson Acoustic wave generation device and equipment including a plurality of such devices

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US7352870B2 (en) * 2002-03-29 2008-04-01 Kabushiki Kaisha Toshiba Active sound muffler and active sound muffling method
JP2004177419A (ja) * 2002-11-22 2004-06-24 Toshiba Corp 能動回折音制御装置
JP2004361938A (ja) * 2003-05-15 2004-12-24 Takenaka Komuten Co Ltd 騒音低減装置
JP2008213547A (ja) * 2007-02-28 2008-09-18 Nissan Motor Co Ltd 騒音制御装置
JP4311487B2 (ja) * 2007-10-23 2009-08-12 トヨタ自動車株式会社 車室内構造
US8737634B2 (en) * 2011-03-18 2014-05-27 The United States Of America As Represented By The Secretary Of The Navy Wide area noise cancellation system and method
DE102012005814B4 (de) 2011-03-19 2014-11-20 Hochschule Mittweida (Fh) Aktive Lärmminderungseinrichtung für sich bewegende Lärmquellen
CN106469551A (zh) * 2015-08-19 2017-03-01 中兴通讯股份有限公司 一种管道降噪系统及方法

Citations (6)

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Publication number Priority date Publication date Assignee Title
DE2139941A1 (de) * 1971-08-10 1973-03-01 Messerschmitt Boelkow Blohm Laermabschirmung durch schallgitter
JPS60150399A (ja) * 1984-01-18 1985-08-08 Matsushita Electric Ind Co Ltd パラメトリツクアレイスピ−カ
DE3922185A1 (de) * 1989-07-06 1991-01-17 Telefonbau & Normalzeit Gmbh Anordnung einer lautsprechergruppe fuer fernsprechkonferenzen
US5315661A (en) * 1992-08-12 1994-05-24 Noise Cancellation Technologies, Inc. Active high transmission loss panel
US5438624A (en) * 1992-12-11 1995-08-01 Jean-Claude Decaux Processes and devices for protecting a given volume, preferably arranged inside a room, from outside noises
EP0787340A1 (de) * 1994-10-20 1997-08-06 Le Comptoir De La Technologie Aktive vorrichtung zur schallintensitätsdämpfung

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2139941A1 (de) * 1971-08-10 1973-03-01 Messerschmitt Boelkow Blohm Laermabschirmung durch schallgitter
JPS60150399A (ja) * 1984-01-18 1985-08-08 Matsushita Electric Ind Co Ltd パラメトリツクアレイスピ−カ
DE3922185A1 (de) * 1989-07-06 1991-01-17 Telefonbau & Normalzeit Gmbh Anordnung einer lautsprechergruppe fuer fernsprechkonferenzen
US5315661A (en) * 1992-08-12 1994-05-24 Noise Cancellation Technologies, Inc. Active high transmission loss panel
US5438624A (en) * 1992-12-11 1995-08-01 Jean-Claude Decaux Processes and devices for protecting a given volume, preferably arranged inside a room, from outside noises
EP0787340A1 (de) * 1994-10-20 1997-08-06 Le Comptoir De La Technologie Aktive vorrichtung zur schallintensitätsdämpfung

Non-Patent Citations (2)

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Title
BOLTON J S ET AL: "SOUND CANCELLATION BY THE USE OF SECONDARY MULTIPOLES", JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA,US,AMERICAN INSTITUTE OF PHYSICS. NEW YORK, vol. 98, no. 4, 1 October 1995 (1995-10-01), pages 2343 - 2362, XP000538051, ISSN: 0001-4966 *
PATENT ABSTRACTS OF JAPAN vol. 009, no. 318 (E - 366) 13 December 1985 (1985-12-13) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8526654B2 (en) 2009-05-20 2013-09-03 Didson Acoustic wave generation device and equipment including a plurality of such devices

Also Published As

Publication number Publication date
US6463156B1 (en) 2002-10-08
FR2799873B1 (fr) 2002-02-08
DE60015902D1 (de) 2004-12-23
FR2799873A1 (fr) 2001-04-20
EP1094444B1 (de) 2004-11-17
ATE282878T1 (de) 2004-12-15
DE60015902T2 (de) 2005-11-24

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