Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/02—Details
  • H04R9/025—Magnetic circuit
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R7/00—Diaphragms for electromechanical transducers; Cones
  • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
  • H04R7/04—Plane diaphragms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R7/00—Diaphragms for electromechanical transducers; Cones
  • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
  • H04R7/12—Non-planar diaphragms or cones
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R7/00—Diaphragms for electromechanical transducers; Cones
  • H04R7/16—Mounting or tensioning of diaphragms or cones
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/02—Details
  • H04R9/04—Construction, mounting, or centering of coil
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2209/00—Details of transducers of the moving-coil, moving-strip, or moving-wire type covered by H04R9/00 but not provided for in any of its subgroups
  • H04R2209/024—Manufacturing aspects of the magnetic circuit of loudspeaker or microphone transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
  • H04R2231/003—Manufacturing aspects of the outer suspension of loudspeaker or microphone diaphragms or of their connecting aspects to said diaphragms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
  • H04R2499/10—General applications
  • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles

Definitions

• the invention relates to the field of acoustic loudspeakers, and more particularly of small speakers. It relates more particularly to a new architecture of loudspeakers that allows to very strongly reduce their thickness, that is to say, their dimension measured perpendicularly to the direction of emission of sound.
• a loudspeaker comprises a mobile membrane mechanically associated with a winding traversed by a current representative of the acoustic signal to be generated.
• the loudspeaker also comprises a magnetic field source, generally constant, which interacts with the current flowing through the winding to allow movement of the winding and therefore of the membrane.
• the winding is disposed in a central zone of the membrane which is itself of generally conical shape, between polar parts that can channel the magnetic field generated by the magnetic field source, which is itself below of the membrane. It is understood that the stacking of these different elements is at the expense of the overall thickness of the speaker. In other words, when it is desired to make a conventional speaker of reduced thickness, it is necessary to reduce the angle of the cone of the membrane, or the dimensions of the magnetic field source, with inevitably a degradation. acoustic performance.
• the acoustic sources are the least thick possible.
• the integration of loudspeakers in vehicle doors or in various furniture elements can be mentioned.
• Such a loudspeaker comprises an annular magnetic assembly disposed at the periphery of the membrane. This set comprises several superimposed magnets, whose magnetizations are radial for the central layer, and axial for the peripheral layers. Such an arrangement makes it possible to concentrate the field lines towards the inside of the ring formed by the magnetic assembly, but has the major disadvantage of limiting the height over which the magnetic field is useful. In other words, the excursion of the membrane is limited, which prevents the speaker from being effective at low frequencies.
• the invention therefore relates to an acoustic loudspeaker which conventionally comprises:
• a source of constant magnetic field oriented in a plane substantially parallel to the membrane
• this loudspeaker is characterized in that the magnetic field source is formed of a set of magnetized elements disposed at the periphery of this membrane, around the winding. Each magnetized element has a cylindrical face facing the winding. The magnetic field generated by these magnetized elements has field lines that emerge from the full height of this inner face of the magnetic field source.
• the invention consists in producing a loudspeaker by arranging the winding around the periphery of the membrane, and positioning the magnetic field source around the membrane, facing the winding.
• the magnetic field generated by the magnetic elements arranged in a ring is therefore radial, and acts directly on the winding without the need for a pole piece.
• the field lines generated by the magnets produce a homogeneous force (in direction and amplitude), on the winding, over the potential excursion of the membrane.
• the outer contour of the membrane, the coil and the magnetic field source are in the same plane, which provides a particularly compact and thin.
• the speaker according to the invention sees the magnetic field close naturally in the surrounding environment.
• This apparent disadvantage is offset by the fact that the mass of magnetic material required is globally important, since it occupies the entire periphery of the membrane.
• the gains in compactness form a largely preponderant advantage.
• the shape of the membrane may be substantially flat, for example for applications in the low frequencies, or of more complex shape, for use at higher frequencies, where it is necessary to benefit from greater rigidity .
• This shape can for example be convex, concave, conical.
• the various magnetized elements are arranged in a ring on the periphery of the membrane in a regular angular distribution, to balance the forces exerted on the coil.
• Different geometries are possible for these magnetic elements. It is thus possible to have substantially rectilinear elements to form a polygonal global geometry. In this case, it is also possible for the winding to be wound into a polygonal shape corresponding to the shape of the magnetic field source, so as to maintain a substantially constant air gap. It is also possible to use magnetized elements having a curvature complementary to that of the winding, so as to provide a source which has a circular overall shape, and which is therefore at a quasi-constant distance from the winding.
• the magnetized elements may have a face oriented on the side of the coil which is cylindrical, so as to maintain a constant air gap regardless of the relative position of the coil.
• the magnetized elements can be mounted inside successive housings made in a frame, itself secured to a fixed point of the installation of the speaker.
• the loudspeaker comprises a suspension member connected on the one hand to the frame of the magnetic field source, and on the other hand to the periphery of the membrane.
• This suspension element allows the displacement of the membrane relative to a fixed point.
• the loudspeaker also comprises a second suspension member, also connected to the frame and the periphery of the membrane, but on the opposite side of the winding with respect to the first suspension member, so as to form a closed volume around the winding .
• the membrane is connected to the chassis of the loudspeaker by a set of two sheets defining an overall volume of substantially toroidal shape, inside which are enclosed the winding and the magnetic field source. Moisture tightness is thus ensured in particular vis-à-vis the winding.
• the presence of the second suspension member also makes it possible to improve the power handling by increasing the return force applied to the moving element. This second suspension member improves the guidance of the coil by creating a deformable parallelogram structure.
• this double suspension makes it possible to balance the mechanical forces with respect to the two directions of movement of the moving equipment, as opposed to single suspension systems.
• this second suspension member is not mandatory because it adds weight to the moving equipment. This second suspension may therefore be omitted for loudspeakers in the ranges where the displaced mass considerations are preponderant.
• Figure 1 is a top view of a speaker according to the invention, wherein a portion of one of the suspension members has been masked to reveal the magnetic field source and the winding;
• Figure 2 is a detail view of a portion of the frame accommodating the magnetized elements.
• Figure 3 is a cross-sectional view, in slight perspective, of the loudspeaker of Figure 1.
• Figure 4 is a cross-sectional detail view of a magnet and facing winding, on which the field lines have been shown.
• the invention therefore relates to a loudspeaker which, as illustrated in FIG. 1, consists essentially of a membrane 2 of circular shape and of substantially flat geometry.
• This membrane also comprises a winding 3 of circular shape which is mechanically secured to the membrane.
• the magnetic field source 4 which comprises a frame 5 supporting different magnetized elements 6.
• the membrane 2 is made in a traditional manner with materials such as, among which may be mentioned, at examples: composite materials (combining glass, aramid or similar fibers, or carbon fibers), metals (especially aluminum, titanium and beryllium), cellulose pulp, polymers such as polypropylene, polyethylene terephthalate (Mylar ® ), or acrylonitrile butadiene styrene (ABS), or even synthetic textiles.
• the shape of the membrane may be flat for use in the low frequencies, or even more complex (concave, convex, conical) to have a superior rigidity appreciable for operations at higher frequency.
• the membrane 2 is peripherally extended by a zone 8 accommodating the coil 3 which is wound circularly around the periphery of the membrane 2.
• the wire used for the winding is of conventional characteristics, and for example based on various electrically conductive materials, and in particular copper, aluminum, and other alloys.
• the wire section can be optimized to minimize the overall resistance of the coil.
• the magnetic source 4 consists essentially of magnetized elements 6 in the form of segments angularly distributed on the periphery of the coil 3.
• these elements 6 may be based on very strong magnetization materials, to compensate the absence of pole piece, and the fact that it is the creepage of these magnetized elements 6 which pass through the coil 3.
• the magnetization of these elements 6 is therefore chosen so that it is oriented radially, and passes through the winding 3 perpendicularly substantially along the plane of the membrane 2. Materials such as neodymium or the like have a magnetization compatible with these applications.
• each of the segments may have a face 10 which is curved, more precisely cylindrical, to be at a constant distance from the winding.
• This face is cylindrical, that is to say that the distance to the coil 3 remains the same regardless of the position of the latter when moving with the membrane.
• the field lines 20 emerge from the plane face 10 of the magnetized element. These field lines are oriented towards the inside of the loudspeaker, towards the winding 3. In this way, during its movements, the winding 3 positively undergoes the influence of the magnetic field, including in its extreme positions. one of which is illustrated by the dotted winding. Over the entire height of the face 10, the field lines 20 have an overall orientation in the direction of the winding, with a sufficiently homogeneous distribution, which helps to limit the phenomena of distortions.
• these curved magnetized elements 6 are disposed inside a chassis 4, which has appropriate housings 12. These housings 12 are formed between radial partitions 15 extending between two adjacent magnet elements 6. Means for holding the magnetized elements may be arranged, for example in the form of a bulge 16 located at the end of the partition 15, and of complementary shape to a recess 17 formed on the short sides of the magnetized elements 6. In this way, a quasi-continuity of the magnetic field generated by the magnetized elements 6 is maintained at the boundary between two successive elements.
• the rear face 19 of the magnetized elements may be flat or curved depending on the type of material used. A wall 18 facing the rear face 19 of the magnetized elements, can advantageously improve the maintenance of these elements 6 on the frame 4.
• the frame 4 has a peripheral portion 20 for fixing the loudspeaker on its support.
• the loudspeaker also comprises suspension members 30, 31 illustrated in FIG. 3.
• Each suspension member 30, 31 has an inner portion 32, 33 which is substantially circular in shape, and secured to one of the faces 34,35 of the membrane 2.
• the opposite end 36,37 forming the outer periphery of the suspension member 30,31 is itself secured to the frame 4 by various appropriate means as a commitment in a throat made for this purpose or a collage, or any other suitable mechanical device.
• the portion 38,39 of the suspension member 30,31 located between its two ends 32,33; 36,37 adopts a curved shape, to generate a space 40 encompassing the magnetic field source and the winding.
• the shape of this central portion 38,39 is chosen to allow the maximum deflection of the membrane 2 without generating mechanical stress.
• Other forms, for example rectangular, can also give satisfaction.
• Materials conventionally used to make the suspensions may be employed, such as coated textiles or the like.
• the loudspeaker according to the invention has multiple advantages, and in particular that of having a particularly reduced thickness with respect to its diameter. It can therefore be advantageously used for applications where congestion constraints are important, and while maintaining good acoustic performance, especially in low frequencies, thanks to the ability to move a relatively large volume of air.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

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• 2010
  • 2010-05-28 FR FR1054130A patent/FR2960738B1/fr active Active
• 2011
  • 2011-05-27 US US13/699,180 patent/US9071898B2/en active Active
  • 2011-05-27 WO PCT/FR2011/051207 patent/WO2011148109A1/fr active Application Filing
  • 2011-05-27 EP EP11726910.0A patent/EP2577992B1/de active Active

Non-Patent Citations (1)

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