WO2015101915A2 - Dispositif à réseau de transducteurs acoustiques - Google Patents

Dispositif à réseau de transducteurs acoustiques Download PDF

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Publication number
WO2015101915A2
WO2015101915A2 PCT/IB2014/067378 IB2014067378W WO2015101915A2 WO 2015101915 A2 WO2015101915 A2 WO 2015101915A2 IB 2014067378 W IB2014067378 W IB 2014067378W WO 2015101915 A2 WO2015101915 A2 WO 2015101915A2
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WO
WIPO (PCT)
Prior art keywords
sub
acoustic transducer
transducer array
structures
connector
Prior art date
Application number
PCT/IB2014/067378
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English (en)
Other versions
WO2015101915A3 (fr
Inventor
Florian Perrodin
Joël Busset
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Distran Gmbh
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Filing date
Publication date
Application filed by Distran Gmbh filed Critical Distran Gmbh
Publication of WO2015101915A2 publication Critical patent/WO2015101915A2/fr
Publication of WO2015101915A3 publication Critical patent/WO2015101915A3/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
    • H04R1/406—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
    • H04R1/04—Structural association of microphone with electric circuitry therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/08—Mouthpieces; Microphones; Attachments therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/003—Mems transducers or their use
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/40—Details of arrangements for obtaining desired directional characteristic by combining a number of identical transducers covered by H04R1/40 but not provided for in any of its subgroups
    • H04R2201/401—2D or 3D arrays of transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2420/00—Details of connection covered by H04R, not provided for in its groups
    • H04R2420/09—Applications of special connectors, e.g. USB, XLR, in loudspeakers, microphones or headphones

Definitions

  • the present invention relates to audio engineering and acoustic transducer assembly.
  • the invention further relates to an acoustic transducer array.
  • 3D shaped acoustic transducer arrays offer the ability to capture a three-dimensional sound field without ambiguity as opposed to using a planar acoustic transducer array. With a planar array, it is often difficult to distinguish sounds coming from one side of the array plane with sounds coming the other side. 3D shaped acoustic transducer arrays also enable better properties such as isotropic properties in the case of spherical acoustic transducer arrays that in particular allow algorithms such as beamforming to have similar performances in every directions.
  • 3D shaped acoustic transducer arrays are however complicated to build because the mechanical structure influences the acoustic properties of the array.
  • CN201369806Y discloses a spheroidal array made of thin rods onto which the microphones are placed. The microphones are still connected to the acquisition unit by individual wires which leads to a high number of wires. No method is disclosed to manage this high number of wires. In reality, such a high number of wires will take up considerable space and thereby have a substantial influence on acoustic properties. Furthermore, the assembly of the mechanical structure remains difficult and expensive with at least 90 rods of at least 2 different lengths to mount together.
  • either the engineer can choose to control exactly the acoustic properties of the structure such as described in EP2592846 by e.g. placing the acoustic transducers on a rigid baffled sphere (a sphere with a rigid surface that prevents the air from going through).
  • the acoustic properties of the baffled sphere have then to be taken into account in the computation of the acoustic field, limiting the classes of algorithms that could be used with the array. It further requires ensuring that no resonances occur inside the sphere.
  • the engineer can choose to limit the acoustic effects of the structure by designing an acoustically transparent structure at the operating frequencies (this property is described hereinafter).
  • the engineer When designing an acoustically transparent structure, the engineer will choose thin tubes or acoustically transparent material.
  • US2012275621 proposes to use flexible printed circuit boards (‘flexprints’) for wiring.
  • Flexprints flexible printed circuit boards
  • PCB printed circuit board
  • a specific problem to be solved by the invention is to reduce the distortion of the sound waves by the cables and the overall electrical and mechanical structure.
  • the mechanical structure instead of having the wires external to the mechanical structure that constitutes a framework to which the transducers are mounted and that defines the position of the transducers, they are included into it or put along the structure (for example by running on their surface) such that the mechanical structure has a double use: first it maintains the acoustic transducers at a fixed place and second it maintains the wires avoiding mechanical stresses and possibly protecting the electrical wires from external ingress.
  • This also improves the overall aspect of the acoustic transducer array, and confers a sense of robustness and sobriety to the structure.
  • the acoustic transducer array comprises a substantial acoustical transparency. This means that in contrast to prior art approaches relying on a rigid sphere, the transducer array in accordance with approaches according to the present invention is of the acoustically transparent type.
  • the acoustic transducer array may be substantially transparent. In an example, this may be achieved by an opacity ratio that is at most 50%, preferably at most 40% or at most 30% or even at most 20% or at most 15%.
  • the electrical conductors are electrical conductors of the wiring of the transducers, i.e. they are operatively connected to the conductors. This of course does not imply that necessarily all conductors are connected to every one of the transducers, rather, the wiring is merely such that transducers of the sub-structures can be contacted from outside of the sub-structure, especially for example from another sub-structure.
  • the electrical conductors are either inside the elements (beams etc.) of the framework, or they are contiguous with them in that they are applied to their surface, for example if parts of the framework itself are constituted by a rigid PCB. In this way, the conductors running between the sub-structures do not contribute to the opacity (that influences the acoustical transparency) and may be largely invisible.
  • All the cables that connect the acoustic transducer array to any external device e.g. an acquisition board, a power unit, an amplifier, an analog to digital converter unit, a computing unit, is denoted hereafter as external connection cable. It comprises all kind of electrical connections e.g. ground wires, power wires, analog signal wires, digital signal wires, differential pairs, flat cables.
  • the transducer array may especially be a 3D transducer array, i.e., an array in which the transducers are arranged in a manner substantially deviating from a 2-dimensional arrangement (arrangement in a plane).
  • the sub-structures themselves may be essentially 2-dimensional (2D).
  • the characteristic for a sub-structure to be essentially 2D is defined by its thickness-to-width ratio.
  • the thickness-to-width ratio is defined as follows: Let B be an enclosing rectangular cuboid of minimal volume of a said sub-structure. Let a x b x c be the dimensions of the said cuboid with a ⁇ b ⁇ c (commonly designated as a the thickness, b the width and c the length). The thickness-to-width ratio is defined as a / b ( a divided by b ). It is thus a number between 0 and 1.
  • Sub-structures that have a maximum thickness-to-width ratio of at most 1/3 are called substantially 2D sub-structures.
  • Acoustic transducers are transducers sensitive to mechanical waves e.g. microphones, particle velocity probes, or devices that measure a combination of pressure and particle velocity. Acoustic sensitivity of such transducers can go below one hertz up to hundreds of gigahertz. In embodiments, however, the operating frequencies (to which the definitions used in this text relate) are below 100 kHz.
  • the invention is especially advantageous to array with a large number of acoustic transducers e.g more than 30 but can also be applied for array with only few acoustic transducers, for example at least 6 or at least 10.
  • the wire connections constituted by the electrical conductors are directly made on at least one PCB. It enables higher track density than classical wires as well as easily sharing some of the cable for the several microphones.
  • MEMS micro-electro-mechanical systems
  • a sub-structure contains at least one flexible or rigid PCB that is connected to at least one other sub-structure.
  • This connection is preferably done using a flexible flat cable and a flat cable connector mounted to said PCB, for example by soldering.
  • PCBs offer many advantages over direct wiring of the elements. As already mentioned, it offers a high density of tracks, possibly on multiple layers.
  • the PCB can be either rigid, or flexible or partly rigid, party flexible, thus offering many possibility in terms of shape. It also speed up the assembly process because it can be assembled by automatized means such as pick-and-place machines.
  • a topology of track wiring is used that brings about a reduction of the number of different PCB layouts.
  • it can be reduced up to having only one common PCB layout for all PCBs. This results in dramatically reduced production costs. It also eases the maintenance of the device by having fewer types of parts.
  • Substantially identical PCB layout has to be understood in the way that the manufacturer of the PCBs produces the PCB with the same topology file.
  • the PCBs could however be populated differently for example not populating some of the connectors or some of the sensing elements, and could be marked differently by e.g. distinct numbers, marks, or symbols.
  • PCB layout can be divided in types, e.g two different types of PCB layout can be used in a design. This helps to keep the number of different part low compared to having only different PCB layout.
  • Acoustic transparency is a property that is relative to the operating frequency.
  • a structure is said acoustically transparent at a given frequency f if sound waves at this frequency f are only slightly perturbed when propagating through the structure in comparison to a free-field propagation.
  • the structure may also be designed in its shape to avoid annoying reflection, refraction, or diffraction.
  • the structure may also have a special structure like the one described in “Experimental Acoustic Ground Cloak in Air” Phys. Rev. Lett. 106, 253901 (2011).
  • the opacity ratio for a substantially 2D sub-structure is defined as follow: Let B be the enclosing rectangular cuboid of minimal volume. Let v be an unitary vector collinear to the smallest edge of B also designated as a thickness vector. P is denoted as the projection of the said sub-structure along vector v .
  • the opacity ratio is defined as the ratio of the area of P divided by the area enclosed by the convex hull of P.
  • the opacity ratio would be the ratio of the dark area on a surface parallel to the main plane of the sub-structure, over the area of the main plane of the sub-structure.
  • An example of opacity computation is drawn figure 3 (see the drawing section).
  • a said sub-structure with an opacity ratio below 50%, preferably below 20% is substantially acoustically transparent, but it is not a necessary condition.
  • the electrical conductors e.g. power wires, signal wires (in each case possibly constituted by electrical conductors of a PCB), of a first said sub-structure may contain at least one conductor that transmit data signal from an acoustic transducer placed on an adjacent second said sub-structure to either an adjacent third said sub-structure or an external connection of the said device.
  • the number of external connection cables to the acoustic transducer array can be dramatically reduced in comparison to the case where each acoustic transducer is directly connected to an external device.
  • At least one sub-structure comprises at least a first connector for connection to a first further sub-structure or an external connection and a second connector for connection to a second further sub-structure or an external connection, each of said connectors comprising a plurality of dedicated contacts with defined contact positions, wherein at least one contact of the first connector is in electrical communication with a contact of the second connector that corresponds to a different contact position.
  • the connectors each may comprise a plurality of groups of contacts, and wherein the groups of contacts may be numbered consistently (so that the numbers of all connectors correspond to each other) so that the contacts of group N+1 of contacts of a first connector (“output connector”) of a sub-structure is in electrical communication with the contacts of group N of contacts of a second connector (“input connector”) for all N.
  • the first group of the first connector may be in communication with the transducers.
  • the acoustic transducers are microphones placed on a printed circuit board, especially the PCB that comprises the electrical conductors.
  • each printed circuit board carries 6 microphones.
  • the printed circuit boards may be protected by the framework and/or a separate cover, such as an aluminum cover, to strengthen the mechanical structure.
  • the sub-structures are mechanically interconnected. This mechanical interconnection may be done by various means, for example by adding mechanical parts not belonging to the frameworks, by coupling members of the frameworks or by gluing.
  • 3D shaped microphone arrays composed of e.g. several planar rigid printed circuit boards possibly electrically connected together, with only a few external connection cable.
  • the acoustic transducer array may be spheroidal.
  • the term spheroidal covers spheres but also every structure approximating a sphere e.g. regular polyhedrons such as an icosahedron, or sufficiently regular spherical structures e.g. a Goldberg polyhedron, for example a “football”- (or fullerene, C60)-like structure.
  • Another geometry of particular interest is cylindrical structures, which may be approximated by an assembly of essentially 2D sub-structures.
  • FIG. 1 shows an exemplary embodiment with an icosahedron shaped structure.
  • FIG. 1 shows an exploded view of one of the sub-structure of the exemplary embodiment already shown Fig. 1.
  • FIG. 1 shows how the opacity ratio of the exemplary embodiment sub-structure presented in Fig 1 and 2 could be computed.
  • FIG. 1 shows a possible electrical schematic of a sub-structure with two connectors.
  • FIG. 1 An exemplary embodiment with an icosahedron shaped structure with 6 microphones on each face for a total of 120 microphones is shown Fig. 1.
  • Five external connection cables 103 concentrate all the signals and required conductors such as ground or power.
  • the 20 sub-structures 101 (only two of them are marked for the sake of clarity) represented as the faces of the icosahedron are mechanically connected to their three nearest neighboring sub-structures using mechanical fastener 102 (only some of them are marked). Most of them are electrically connected to two neighboring sub-structures in a similar manner as shown Fig. 5. Some of the sub-structures are connected to external connection cable 103.
  • the sensors (not shown in this figure) are in communication with the ambient air through the holes 104 (only some of them are marked).
  • the spheroidal structure diameter is in this exemplary embodiment of about 60cm.
  • Figure 2 represents an exploded view of one of the sub-structure 101 of the exemplary embodiment shown fig. 1.
  • the sensors 202 are MEMS microphones and are protected by an upper aluminum cover 201 and a bottom cover 204.
  • the structure is electrically connected to other structures using two of the three flat cable connectors 203.
  • the characteristic size of the obstacles formed by the thin sticks of the mechanical structure 201 and 204 are about six millimeters resulting in an acceptable acoustic transparency for frequency well below 68kHz, e.g. 10kHz, for an array in the air in standard ambient temperature and pressure.
  • Figure 3 represents how the opacity ratio is calculated for the sub-structure of the exemplary embodiment of figures 1 and 2.
  • the hatched area 301 represents the projection of the sub-structure on the plane (denoted as P is the description) perpendicular to the thickness vector.
  • the dotted area represent the interior area of the convex hull 302 of the projection where the area 301 has been removed.
  • the opacity ratio is thus the ratio of the hatched area 301 over the sum of the dotted area and the hatched area 301. In this embodiment, it is about equal to 20%.
  • FIG. 4 An exemplary embodiment of an electrical schematic of a sub-structure is shown Fig. 4; Fig. 5 shows a detail illustrating how the sub-structures may be electrically connected.
  • Each of the solid rectangles denotes a sub-structure 403 with a plurality of transducers (also denoted “sensors (S)” in this text; reference number 405 in Fig. 5).
  • S sensors
  • the electrical conductors within the sub-unit are illustrated by thick solid lines (the lines contacting the sensors 405; through-going conductors 406); in reality each thick solid line represents an electrical bus, which is a plurality of electrical conductors.
  • Vertical thick solid lines present in Fig. 4 and 5 are graphical elements used to represent the contents of the bus; for illustration purposes, each group 404 contains 5 conductors.
  • the sub-structure 403 contains two main connectors 401 and 402.
  • the two connectors 401 and 402 may be of different size and structure e.g. different component references.
  • Each connector 401 and 402 has several groups of electrical contacts 404; each group 404 includes at least one conductor, and is characterized by being finally connected to the electronic components of one given board. All groups have the same number of contacts. In this drawing, all groups 404 have five contacts and the connectors 401 and 402 may be 20-pin connectors.
  • the first group 404 named A is connected to the electronic components and to the sensors 405 of the board 403. In this example embodiment, two sensors 405 are represented. Conductors may also be shared within groups e.g. grounds, powers or signal buses.
  • the second group 404 B of the connector 401 is connected through a group of electrical conductors 406 to the first group 404 of connector 402.
  • the third group 404 of connector 401 is connected through a group of electrical conductors 406 to the second group 404 of the connector 402.
  • the general formula is to connect the group 404 (N+1) of connector 401 to the group 404 (N) on connector 402.
  • the sensors of the first sub-structure can be contacted via group A of the connector 401 of the first sub-structure, the sensors of the second sub-structure via group B of the connector 401 of the first sub-structure, the sensors of the third sub-structure via group C of the connector 401 of the first sub-structure, etc.
  • connectors 401 and 402 of the different sub-structures are that 401 can be mated with 402 using preferably a flexible flat cable 501.
  • a person skilled in the art will be able to conceive boards with different number of connectors and with arbitrary number of conductors and in particular, for 3D shaped array built from a 2D manifold e.g. a sphere, a cylinder... will probably choose to use more than two types of different connectors. Additional wires may also be added that does not follow the preceding rules e.g shared wiring for LED control.
  • each sub-structure 403 is identical while all the four groups 404 A, B, C and D are connected to sensors 405 of different boards 403.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Transducers For Ultrasonic Waves (AREA)

Abstract

La présente invention se rapporte à un réseau de transducteurs acoustiques qui comprend une pluralité de sous-structures interconnectées mécaniquement. Chaque sous-structure comporte un cadre mécanique et au moins un transducteur acoustique monté sur le cadre. Chaque sous-structure inclut une pluralité de conducteurs électriques connectés fonctionnellement aux transducteurs. Le réseau de transducteurs possède une transparence acoustique importante, et les conducteurs électriques se trouvent à l'intérieur du cadre ou sont contigus au cadre.
PCT/IB2014/067378 2013-12-31 2014-12-29 Dispositif à réseau de transducteurs acoustiques WO2015101915A2 (fr)

Applications Claiming Priority (2)

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CH21662013 2013-12-31
CH02166/13 2013-12-31

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WO2015101915A2 true WO2015101915A2 (fr) 2015-07-09
WO2015101915A3 WO2015101915A3 (fr) 2015-11-12

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201369806Y (zh) 2009-02-02 2009-12-23 中国科学院声学研究所 一种球形传声器阵列
US20120275621A1 (en) 2009-12-22 2012-11-01 Mh Acoustics,Llc Surface-Mounted Microphone Arrays on Flexible Printed Circuit Boards
EP2592846A1 (fr) 2011-11-11 2013-05-15 Thomson Licensing Procédé et appareil pour traiter des signaux d'un réseau de microphones sphériques sur une sphère rigide utilisée pour générer une représentation d'ambiophonie du champ sonore

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7365476B2 (en) * 2004-02-27 2008-04-29 The Boeing Company Methods and systems for supporting acoustical transducers

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201369806Y (zh) 2009-02-02 2009-12-23 中国科学院声学研究所 一种球形传声器阵列
US20120275621A1 (en) 2009-12-22 2012-11-01 Mh Acoustics,Llc Surface-Mounted Microphone Arrays on Flexible Printed Circuit Boards
EP2592846A1 (fr) 2011-11-11 2013-05-15 Thomson Licensing Procédé et appareil pour traiter des signaux d'un réseau de microphones sphériques sur une sphère rigide utilisée pour générer une représentation d'ambiophonie du champ sonore

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Experimental Acoustic Ground Cloak in Air", PHYS. REV. LETT., vol. 106, 2011, pages 253901

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