Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/06—Loudspeakers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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
  • H04R2209/022—Aspects regarding the stray flux internal or external to the magnetic circuit, e.g. shielding, shape of magnetic circuit, flux compensation coils

Definitions

• the present invention relates to a magnetic structure for a motor without an electrodynamic loudspeaker, motors comprising such a structure as well as loudspeakers. It has applications in the industrial field of sound reproduction and sound, including premises.
• Electrodynamic loudspeakers usually comprise a cylindrical coil mechanically secured to an emissive acoustic surface, also called a membrane.
• the spool is generally carried by a straight mandrel integral with the membrane.
• This emissive acoustic surface is usually conical (cone) or spherical (dome).
• the loudspeakers have a cylindrical axis of symmetry in general although there are elliptical loudspeakers. They also include a fixed magnetic circuit whose function is to create in a gap a radial magnetic field on the coil.
• the magnetic iron cores generally comprise an annular or discoidal magnet with axial magnetization and ferromagnetic parts intended to channel the magnetic flux through the coil.
• the application WO 96/04706 "Axially focused radial magnet voice coil actuator" of M. STRUGACH, proposes the use of radial magnets.
• the proposed magnetic element comprises iron or a soft ferromagnetic material.
• the high-speed engine has a superimposition of three magnets of the same remanent magnetization and polarizations of the magnetic fields alternated at 90 ° to each other and whose magnetic polarization orientations are such that the looping of the magnetic field outside the magnets is essentially on the side of the air gap as shown in Figure 4 of this document.
• the invention relates to a magnetic field generating magnetic field for an electrodynamic moving coil loudspeakerless motor, the magnetic structure generating a magnetic field in a gap in which the coil is disposed, said magnetic structure being formed of the stack of three magnets corresponding to an intermediate magnet and two top and bottom overlapping magnets, said magnets having their edges delimiting the air gap aligned and forming a right gap border, said magnets being furthermore contiguous, intermediate magnet having a radial magnetic polarization, the cover magnets having the same magnetic polarization and substantially identical remanent magnetizations.
• the covering magnets have a radial or axial magnetic polarization and when the magnetic polarization of the covering magnets is radial, the remanent magnetization of each covering magnet is greater than the remanent magnetization of the intermediate magnet, and when the magnetic polarization of the lap magnets is axial, the remanent magnetization of each lap magnet is less than the remanent magnetization of the intermediate magnet.
• magnet in the context of the invention covers both a single magnet (pellet, ring / crown), an assembly of magnets (including tiles) as will be explained.
• the residual magnetization of each covering magnet is greater or lesser than 1% of the remanent magnetization of the intermediate magnet, and preferably 5%,
• the residual magnetization of each covering magnet is greater than or less than 10% of the residual magnetization of the intermediate magnet
• the covering magnets are identical to one another in size
• the covering magnets are identical to one another in volume
• the covering magnets are identical to one another in shape
• the widths of the covering magnets are identical
• the width of each covering magnet is smaller than the width of the intermediate magnet
• the width of each covering magnet is equal to the width of the intermediate magnet
• the width of each covering magnet is greater than the width of the intermediate magnet
• edges on the air gap of each of the three magnets are on the same vertical generatrix, (the edges of each of the three magnets bordering the gap are aligned)
• the three magnets have the same magnetic polarization, the polarization being radial (horizontal), the polar faces of the same sign of the three magnets bordering the air gap, the remanent magnetization of each covering magnet being greater than the residual magnetization of the magnet; intermediate magnet,
• the intermediate magnet has a radial magnetic polarization (horizontal) and the two magnets cover a coaxial magnetic polarization (vertical because parallel to) to the axis of symmetry of the loudspeaker, the signs of the polar faces of the covering magnets at the contact of the intermediate magnet being identical and of the same sign than that of the polar face bordering the gap of the intermediate magnet, the remanent magnetization of each covering magnet being lower than the remanent magnetization of the intermediate magnet,
• At least one of the magnets with radial magnetic polarization consists of an assembly of elementary magnets (or tiles) juxtaposed on a circumference (or other suitable form) to form a ring or ring,
• magnets block crown (monolithic block / piece)
• magnets with magnetic polarization coaxial with the axis of symmetry of the loudspeaker are pellet block magnets (monolithic / one-piece block)
• the magnetic structure is internal
• the magnetic structure is external
• the magnetic structure is cylindrically symmetrical
• the dimensions and magnetizations of the internal magnetic structure are independent of those of the external magnetic structure (indeed, apart from the case of a cylindrical symmetry, more generally the internal structure creates its own uniform field with its own dimensions and the external structure creates its own uniform field with its own dimensions, the total field being the sum of the two, always uniform, in general the possible defects of one structure can be compensated by the other structure)
• the loudspeaker r is circular, elliptical, even square or substantially square.
• the invention also relates to an electrodynamic loudspeaker motor such that it comprises a single magnetic structure according to one or more of the described characteristics, said magnetic structure being able to be internal (towards the center of the motor) or external with respect to the coil.
• the invention also relates to a motor for an electrodynamic loudspeaker such that it comprises in opposite and same level (height) two internal and external magnetic structures with respect to the coil, each of the structures being according to one or
• the magnetic polarizations of similar magnets are identical in two magnetic structures.
• the magnetic structures are symmetrical geometrically and by revolution with respect to the coil. In another, they are not, or only partly.
• the invention finally relates to a loudspeaker comprising a motor according to one or more of the characteristics described.
• one of the aims of the invention is to obtain, in the air gap along the generatrix carrying the coil, a substantially constant induction (magnetic field) and, preferably, a height corresponding at least substantially to the height. of the external magnet.
• An induction is considered to be substantially constant if it does not vary more than 1% and, preferably, even better, if it does not vary by more than 0.5%, over the height considered.
• Figure 1 which shows a schematic vertical section of a voice coil loudspeaker, the section passing through the vertical anteroposterior axis of cylindrical symmetry of said loudspeaker and showing a first type of electrodynamic motor with external magnetic structure and even magnetic radial polarization of magnets
• Figure 2 which shows a schematic vertical section of a voice coil loudspeaker, the cut passing through the vertical anteroposterior axis of cylindrical symmetry of said loudspeaker and showing a second type of electrodynamic motor with external magnetic structure and even radial magnetic polarization of magnets
• FIG. 1 shows a schematic vertical section of a voice coil loudspeaker, the section passing through the vertical anteroposterior axis of cylindrical symmetry of said loudspeaker and showing a first type of electrodynamic motor with external magnetic structure and even magnetic radial polarization of magnets
• Figure 2 which shows a schematic vertical section of a voice coil loudspeaker, the cut passing through the vertical anteroposterior axis of cylindrical symmetry
• FIG. 3 which represents a schematic vertical section of a voice coil loudspeaker, the section passing through the antero-posterior axis vertical plane of cylindrical symmetry of said loudspeaker and showing a third type of electrodynamic motor with external magnetic structure and even magnetic radial polarization of magnets
• Figure 4 which shows a schematic vertical section of a voice coil loudspeaker, the section passing through the vertical anteroposterior axis of cylindrical symmetry of said loudspeaker and showing a fourth type of electrodynamic motor with external magnetic structure and magnetic cross-polarizations of magnets
• Figure 5 which shows a schematic vertical section of a top voice coil loudspeaker, the section passing through the vertical anteroposterior axis of cylindrical symmetry of said loudspeaker and showing a fifth type of electrodynamic motor with external and internal magnetic structures of the same magnetic radial polarization of magnets and with symmetry of revolution in magnetization and size between the internal and external structures
• Figure 6 which represents a schematic vertical section of a loudspeaker
• the loudspeaker 1 in Figure 1 comprises a coil 2 carried by a mandrel 3 secured to a membrane 4 and 4 'which is not detailed here and which are movable elements of the top speaker.
• the coil is immersed in a static magnetic field in an air gap (the term gap is used generically even if there is no iron for looping of the magnetic field outside the gap in the engine of the invention which is without iron).
• the magnetic field of the gap is created by a fixed magnetic structure 5 generating said magnetic field and which is here external.
• a force is generated which causes displacements called excurations of the coil, mandrel and membrane.
• the other elements of the speaker such as the salad bowl or the / the mechanical suspensions ("spider" in particular) are not shown for reasons of simplification.
• the magnetic structure is in this external example because to the outside of the mandrel 3 door coil 2 (the axis 6 of cylindrical symmetry of the loudspeaker 1 is considered central and is inward relative to the mandrel / coil).
• the magnetic structure comprises a stack of three magnets, an intermediate 8 and two top cover 7 and bottom 9, of the same radial magnetic polarization (horizontal in Figure 1): the signs of the polar faces on the air gap are identical (either North, be south).
• the width (horizontal measurement in Figure 1) of all these magnets is identical.
• the intermediate magnet 8 has a remanent magnetization less than that of each of the two overlapping magnets 5 and 9.
• the upper (upper) and lower (lower) (lower) ) sandwich the intermediate magnet 8, all these magnets being contiguous to each other.
• the loudspeaker of FIG. 1 implements two rings with radial magnetic polarizations (covering magnets 7 and 9), one above and one below the magnetic biasing intermediate magnet 8. radial.
• the magnets constituting these two rings 7 and 9 have a remanent magnetization greater than the remanent magnetization of the intermediate magnet 8.
• magnet in the context of the invention covers both a single magnet and a magnet formed of the assembly of several elementary magnets. This last case is essentially considered for magnets with radial magnetic polarization (horizontal in the Figure) for which we can implement assemblies of elementary magnets (also called tiles) juxtaposed on a conference (or ellipse or other depending on the type loudspeaker).
• the magnetic structure 5 is internal to the mandrel, that is to say disposed towards the center of the speaker relative to the mandrel.
• two identical magnetic structures are implemented on either side of the mandrel. In the latter case, it is understood that since the diameters are different between the structure magnetic internal and external, the own magnetic fields generated can be different between the two structures.
• the volumes of the magnets are adjusted to equalize these magnetic fields between the internal and external structures.
• Figures 2 and 3 show variants in which the high covering magnets 7 ', 7 “and low 9', 9” have identical widths but width which is however lower ( Figure 2) or greater ( Figure 3) to that of the intermediate magnet 8 ', 8 "In the magnetic structures 5' and 5" of Figures 2 and 3, the cover magnets 7 ', 7 “and 9', 9” are arranged so that their polar faces the air gap are on the same plane as that of the intermediate magnet 8 ', 8 ".It is understood that this is valid for both an internal magnetic structure and external (with respect to the spool mandrel) so that the edge of gap be straight.
• the intermediate magnet is N48 10mm high and 12mm wide and the cover magnets are N52 and each have a height of 3mm and a width of 10mm.
• This configuration makes it possible to obtain a uniform magnetic field of 0.77 Tesla in a 2 mm wide gap at the coil-carrying mandrel (which is then approximately 1 mm from the edge of the gap).
• the intermediate magnet 8 has a radial magnetic polarization (horizontal in the FIG.)
• the magnetic polarizations of the high 11 and the low 12 overlapping magnets are, when they are axial (vertical on the Figure and therefore parallel to the axis of symmetry 6 of the speaker).
• these magnetic polarizations of the covering magnets 11, 12 are opposed to each other. The signs of the polar faces of these three magnets are such that the generated magnetic field is preferentially directed towards the gap.
• the looping (loopback) of the generated magnetic field is quoted air gap since the polar side of the air gap of the intermediate magnet 8 is of sign opposite to the sign of the free polar faces (high and low in the Figure) 11 and 12 overlapping magnets.
• the remanent magnetization of the intermediate magnet 8 is greater than the remanent magnetization of each of the covering magnets 1 1 or 1 2.
• a configuration according to FIG 4 with intermediate magnet 8 of 1, 4 Tesla and cover magnets 1 1, 1 2 of 1, 1 Tesla each, could be calculated and it generates a magnetic induction of 0.62 Tesla on 65% of the height of the intermediate magnet.
• the dimensions and / or magnetizations of the internal magnetic structure are independent of those of the external magnetic structure. Two embodiments of this type have been shown in FIGS. 6 and 7. It will therefore be understood that all the combinations of size difference and / or magnetization between the internal and external structures are envisaged within the scope of the invention.
• the global organizations of the magnetic polarization of the internal and external magnetic structures remain identical, ie all radial internally and externally (see FIG. 5 and 6) or both in axial + radial combination (see Fig. 7).

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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• 2007
  • 2007-09-18 FR FR0757657A patent/FR2921224B1/fr not_active Expired - Fee Related
• 2008
  • 2008-09-18 US US12/300,883 patent/US8055010B2/en active Active
  • 2008-09-18 AU AU2008309455A patent/AU2008309455B2/en not_active Ceased
  • 2008-09-18 JP JP2010525406A patent/JP5535917B2/ja active Active
  • 2008-09-18 CN CN200880112019A patent/CN101828408A/zh active Pending
  • 2008-09-18 WO PCT/FR2008/051678 patent/WO2009047455A2/fr not_active Ceased
  • 2008-09-18 EP EP08836843.6A patent/EP2204048B1/de active Active
  • 2008-09-18 CA CA2700031A patent/CA2700031C/fr not_active Expired - Fee Related

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