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
  • 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
  • H04R7/127—Non-planar diaphragms or cones dome-shaped
• • 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
  • H04R9/04—Construction, mounting, or centering of coil
  • H04R9/045—Mounting
• • 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
  • H04R2209/021—Reduction of eddy currents in the magnetic circuit of electrodynamic loudspeaker transducer

Definitions

• the present invention relates to an electroacoustic transducer.
• an electroacoustic transducer of a headphone unit is provided with a magnetic circuit section as a component that forms a magnetic gap, which is a space in which a voice coil vibrates (see, for example, Patent Document 1).
• the magnetic circuit section includes a permanent magnet, a yoke on which the permanent magnet is arranged, and a pole piece arranged so as to cover the permanent magnet, and forms a magnetic closed loop circuit.
• the members constituting the magnetic circuit portion, such as the yoke and the pole piece are made of electromagnetic soft iron, for example.
• members having sufficient thickness are used to ensure driving force for driving the diaphragm.
• an object of the present invention is to provide an electroacoustic transducer that can reduce loss of driving force due to the influence of eddy current in a magnetic circuit section and improve sound quality. With the goal.
• One aspect of the present invention includes a diaphragm to which a voice coil is connected, and a magnetic circuit section that forms a magnetic gap that is a space in which the voice coil vibrates, and the magnetic circuit section is magnetized in a thickness direction.
• a permanent magnet a pole piece magnetically connected to one surface of the permanent magnet in the thickness direction, a bottom part on which the permanent magnet is arranged, and a part from the periphery of the bottom part to the bottom part.
• a yoke body including a peripheral wall portion extending away from the pole piece and the yoke body magnetically connected to the other surface in the thickness direction of the permanent magnet at the bottom surface portion; At least one of the bottom portions provides an electroacoustic transducer in which a plurality of magnetic metal plates are laminated in the thickness direction of the permanent magnet in a state where they are electrically insulated from each other.
• the electroacoustic transducer further includes a ring yoke disposed around the pole piece, the ring yoke being magnetically connected to the yoke body and forming the magnetic gap between the electroacoustic transducer and the pole piece,
• the ring yoke may be a laminate in which a plurality of magnetic metal plates are stacked in the thickness direction of the permanent magnet while being electrically insulated from each other.
• a recess to which the laminate of the bottom part is fixed is formed in the peripheral wall part, and the recess has a receiving surface for receiving one surface of the laminate of the bottom part, and a receiving surface for receiving one surface of the laminate of the bottom part, and a receiving surface for receiving the laminate of the bottom part. and an inner circumferential surface that supports the outer circumferential surface of the laminate.
• Both the bottom surface part and the peripheral wall part are laminated bodies in which the plurality of magnetic metal plates are stacked in a state where they are electrically insulated from each other, and in the peripheral wall part, the plurality of magnetic metal plates are stacked in the permanent state. They may be laminated in the thickness direction of the magnet.
• adjacent magnetic metal plates may be bonded together with an adhesive so that the magnetic metal plates are electrically insulated from each other.
• the permanent magnet is cylindrical or cylindrical
• the pole piece is a laminate in which a plurality of circular magnetic metal plates are laminated
• the bottom part of the yoke body is also formed of a plurality of circular magnetic metal plates.
• the number of laminated magnetic metal plates constituting the pole piece is the same as the number of laminated magnetic metal plates constituting the ring yoke, and the thickness of each magnetic metal plate of the pole piece and the ring yoke are the same.
• the thickness of each magnetic metal plate may be the same.
• the present invention it is possible to reduce the loss of driving force due to the influence of eddy currents in the magnetic circuit section, and to improve the sound quality.
• FIG. 1 is a cross-sectional view showing the configuration of an electroacoustic transducer according to a first embodiment. It is a sectional view showing a magnetic circuit part of an electroacoustic transducer.
• FIG. 3 is a perspective view showing the appearance of a magnetic circuit section.
• FIG. 3 is a schematic diagram for explaining eddy currents generated in a laminate.
• FIG. 3 is a cross-sectional view showing the configuration of an electroacoustic transducer according to a second embodiment.
• FIG. 6 is a cross-sectional view showing separated parts of the yoke body of the electroacoustic transducer of FIG. 5;
• FIG. 7 is a cross-sectional view showing the configuration of a modification of the second embodiment.
• FIG. 1 is a sectional view showing the configuration of the electroacoustic transducer 100 according to the first embodiment.
• FIG. 2 is a cross-sectional view showing the magnetic circuit section 20 of the electroacoustic transducer 100.
• FIG. 3 is a perspective view showing the appearance of the magnetic circuit section 20.
• terms indicating directions such as “top”, “bottom”, “right”, and “left” are used according to the orientation of objects depicted in the drawings, but these terms do not refer to the present invention. It is not intended to be used as a limitation.
• the “up” and “down” directions correspond to the thickness direction of the electroacoustic transducer 100.
• the electroacoustic transducer 100 is a dynamic electroacoustic transducer that includes a diaphragm 10, a unit holder 15, and a magnetic circuit section 20.
• the electroacoustic transducer 100 is used, for example, as a component of headphones or speakers.
• the magnetic circuit section 20 is made of a plurality of magnetic metals in order to reduce loss of driving force due to eddy currents generated in the magnetic circuit section 20. It is made up of a laminate of plates.
• the pole piece 25 and ring yoke 27 that constitute the magnetic circuit section 20 are a laminate.
• the components other than the magnetic circuit section 20 may have conventionally known configurations. Each part will be explained below.
• the diaphragm 10 is a vibrator that vibrates the surrounding air with its own vibration and outputs sound waves.
• the diaphragm 10 has a center dome 11, a sub-dome 12, and a voice coil section 13.
• the center dome 11 is a portion formed in a dome shape and is located near the center of the electroacoustic transducer 100.
• the sub-dome 12 is also called an edge and is located around the center dome 11.
• the sub-dome 12 is provided integrally with the center dome 11, and the outer peripheral portion of the sub-dome 12 is fixed to a unit holder 15.
• the voice coil section 13 is a member connected to the back surface (lower surface in FIG. 1) of the diaphragm 10.
• the voice coil section 13 includes a cylindrical support 13a and a voice coil 13b fixed to the support 13a.
• the voice coil 13b is located within the magnetic gap G, and when a current flows through the voice coil 13b, a driving force that vibrates the diaphragm 10 is generated.
• the unit holder 15 is a member to which the magnetic circuit section 20 and the diaphragm 10 are attached.
• the unit holder 15 is made of resin, for example, and includes a unit holding part 16 and a flange part 17.
• the unit holding portion 16 is, for example, a cup-shaped portion having a circular outline, and the magnetic circuit portion 20 is disposed therein.
• the flange portion 17 is a portion formed around the unit holding portion 16 and extends radially outward from the upper end of the unit holding portion 16.
• the magnetic circuit section 20 includes a yoke body 21, a permanent magnet 23, a pole piece 25, and a ring yoke 27, as shown in FIGS. 1 to 3.
• the magnetic circuit section 20 forms a magnetic gap G, which is a space in which the voice coil section 13 vibrates.
• a configuration in which a through hole 20h (see FIG. 3) is formed in the center of the magnetic circuit section 20 is illustrated, but the present invention is not limited to such a configuration.
• the yoke body 21 is a cup-shaped magnetic member that forms a space that accommodates the permanent magnet 23. Specifically, the yoke body 21 has a circular outline. As shown in FIG. 2, the yoke main body 21 has a bottom portion 21a and a peripheral wall portion 21b.
• the bottom surface portion 21a is disc-shaped, and in this example, an opening portion 21h is formed in the center portion.
• a permanent magnet 23 is arranged on the bottom surface portion 21a.
• the peripheral wall portion 21b extends from the periphery of the bottom portion 21a in a direction away from the bottom portion 21a (upward in the drawing). Specifically, the peripheral wall portion 21b extends perpendicularly to the bottom surface portion 21a.
• a ring yoke 27 is arranged at the upper end of the peripheral wall portion 21b.
• the permanent magnet 23 is arranged on the bottom surface part 21a, and the ring yoke 27 is arranged on the upper end of the peripheral wall part 21b.
• the yoke body 21 is magnetically connected to the permanent magnet 23 and also to the ring yoke 27.
• the permanent magnet 23 has a cylindrical shape, for example, and is magnetized in the thickness direction. Specifically, the permanent magnet 23 is magnetized, for example, so that the side closer to the diaphragm 10 has a north pole and the opposite side has a south pole.
• the permanent magnet 23 has a flat upper surface 23a and a flat lower surface 23b (see FIG. 1).
• the upper surface 23a corresponds to one surface of the permanent magnet in the thickness direction
• the lower surface 23b corresponds to the other surface of the permanent magnet in the thickness direction.
• the permanent magnet may have a cylindrical shape.
• the pole piece 25 is a magnetic material placed on the upper surface 23a of the permanent magnet 23.
• the pole piece 25 has a disc-like shape with an open center.
• the ring yoke 27 is also made of a magnetic material and is arranged around the pole piece 25 to form a magnetic gap G between it and the pole piece 25.
• FIG. 20 Since the magnetic circuit section 20 has the above structure, as shown in FIG. A closed loop circuit is formed. In this circuit, a magnetic field is generated in the direction shown by the arrow in FIG.
• pole piece 25 and the ring yoke 27 are each configured as a laminate consisting of a plurality of magnetic metal plates instead of a single plate.
• the pole piece 25 and the ring yoke 27 are each composed of three magnetic metal plates.
• the number of magnetic metal plates may be two or four or more.
• the pole piece 25 includes a first magnetic metal plate 26-1, a second magnetic metal plate 26-2, and a third magnetic metal plate 26-3 (hereinafter simply referred to as (Also referred to as "magnetic metal plate 26").
• the magnetic metal plate 26 is a circular thin plate with a circular opening formed in the center.
• the magnetic metal plate 26 has a diameter larger than the diameter of the permanent magnet 23 in this example.
• the material of the magnetic metal plate 26 is preferably a high magnetic flux density soft magnetic material that has high saturation magnetic flux density and magnetic permeability.
• the magnetic metal plate 26 is, for example, an alloy of iron and cobalt. More specifically, the material of the magnetic metal plate 26 is, for example, permendur.
• the thickness of the magnetic metal plate 26 is, for example, 0.1 mm or more and 1 mm or less.
• the pole piece 25 of this embodiment has a structure in which three 0.4 mm magnetic metal plates 26 are laminated.
• the plurality of magnetic metal plates 26 are stacked such that adjacent magnetic metal plates 26 are electrically insulated from each other.
• the magnetic metal plates 26 are bonded to each other using an insulating adhesive, for example, and the magnetic metal plates 26 are electrically insulated from each other by the adhesive.
• the adhesive for example, an anaerobic adhesive is used.
• the pole piece 25 is arranged on the upper surface 23a of the permanent magnet 23.
• the pole piece 25 may be arranged in such a manner that it is magnetically connected to the permanent magnet 23, and may be arranged directly on the upper surface 23a or with another member (not shown) interposed therebetween. may be done.
• the ring yoke 27 is also a laminate made of a plurality of magnetic metal plates.
• the ring yoke 27 includes a first magnetic metal plate 28-1, a second magnetic metal plate 28-2, and a third magnetic metal plate 28-3 (hereinafter simply referred to as "magnetic metal plate 28").
• the number of laminated magnetic metal plates 26 constituting the pole piece 25 and the number of laminated magnetic metal plates 28 constituting the ring yoke 27 are, for example, the same.
• the magnetic metal plate 28 has an annular shape with a larger diameter than the magnetic metal plate 26 of the pole piece 25.
• the material and thickness of the magnetic metal plate 28 are, for example, the same as the magnetic metal plate 26 of the pole piece 25. In this way, when the material and thickness of the magnetic metal plate 28 are the same as those of the magnetic metal plate 26 of the pole piece 25, when manufacturing the magnetic metal plate 26 and the magnetic metal plate 28, a high yield can be obtained from a single steel plate. There is an advantage that the magnetic metal plate 26 and the magnetic metal plate 28 can be manufactured.
• the plurality of magnetic metal plates 28 are laminated by pressing using, for example, an anaerobic adhesive.
• the ring yoke 27 which is a laminate, is manufactured.
• the thickness of the pole piece 25 and the thickness of the ring yoke 27 are, for example, the same.
• the present invention is not limited to such a configuration.
• the magnetic metal plates may be electrically insulated from each other by an insulating film formed on the surface of the magnetic metal plates.
• FIG. 4 is a schematic diagram for explaining eddy currents generated in the laminate.
• a part of the cross section of the pole piece 25 is shown as an example of a laminate.
• the eddy current generated in the cross section of each magnetic metal plate 26 of the pole piece 25 is reduced compared to the case where the pole piece 25 is configured of a single member.
• the pole piece 25 is a single member having a thickness comparable to that of the three magnetic metal plates 26 in FIG. 4
• the eddy current flowing inside the member is large, and the driving force is accordingly The loss will be large.
• the eddy current generated in the cross section of the magnetic metal plate 26 is reduced, so the loss of driving force is reduced.
• the electroacoustic transducer 100 of the present embodiment since the pole piece 25 and the ring yoke 27 are configured as a laminate, the electroacoustic transducer 100 generates noise within these members when the electroacoustic transducer 100 operates. Eddy currents are reduced and loss of driving force can be reduced. As a result, the sound quality of the electroacoustic transducer 100 is improved.
• the electroacoustic transducer of one form of the present invention may not include the ring yoke 27 and only the pole piece 25 may be structured as a laminate. good.
• FIG. 5 is a sectional view showing the configuration of an electroacoustic transducer 101 according to the second embodiment.
• FIG. 6 is a cross-sectional view showing parts of the yoke body 121 of the electroacoustic transducer 101 of FIG. 5 in isolation.
• the configuration of the yoke body 121 is different from the yoke body 21 of the first embodiment.
• the other configurations are the same as those of the first embodiment, so common explanations will be omitted.
• the yoke main body 121 of the electroacoustic transducer 101 has a bottom portion 121a and a peripheral wall portion 121b.
• the shape of the yoke body 121 is, for example, the same as the yoke body 21 of the first embodiment.
• the bottom surface portion 121a is a laminate in which a plurality of magnetic metal plates are laminated.
• the material of the magnetic metal plate of the bottom portion 121a is, for example, the same as the material of the pole piece 25 and the ring yoke 27.
• the bottom portion 121a includes a first magnetic metal plate 122-1, a second magnetic metal plate 122-2, and a third magnetic metal plate 122-3 (hereinafter referred to as (also simply referred to as "magnetic metal plate 122").
• the magnetic metal plate 122 is formed to have a larger diameter than the diameter of the permanent magnet 23.
• the diameter of the magnetic metal plate 122 is larger than the diameter of the pole piece 25 and smaller than the diameter of the ring yoke 27.
• the diameter of the magnetic metal plate 122 may be the same as the diameter of the pole piece 25 or the diameter of the ring yoke 27.
• the three magnetic metal plates 122 are laminated by press working, for example, using an anaerobic adhesive, like the magnetic metal plates of the pole piece 25 and ring yoke 27, for example.
• the bottom surface portion 121a which is a laminate of three magnetic metal plates 122, is fitted into a recess 121c formed in the peripheral wall portion 121b.
• the recess 121c is a recess with a circular outline to which the bottom surface 121a is fixed, and has a receiving surface 121d and an inner circumferential surface 121e.
• the receiving surface 121d is a surface that receives one surface (the surface on the top side in the figure) of the laminate of the bottom surface portion 121a.
• the receiving surface 121d is, for example, a plane perpendicular to the thickness direction of the yoke main body 121.
• the inner circumferential surface 121e is the inner surface of a cylinder, and has an inner diameter slightly larger than the diameter of the bottom surface portion 121a.
• the inner peripheral surface 121e supports the outer peripheral surface of the bottom part 121a with the bottom part 121a disposed in the recess 121c, thereby defining the position of the bottom part 121a.
• the depth of the recessed portion 121c is, for example, the same as the thickness of the laminate of the bottom portion 121a.
• the bottom surface portion 121a which is a part of the yoke main body 121, is also configured as a laminate in which a plurality of magnetic metal plates are laminated. Therefore, compared to the configuration of the first embodiment, the eddy current is further reduced, and the loss of driving force can be reduced.
• the bottom portion 121a may not be constructed entirely as a laminate, but only a portion thereof may be constructed as a laminate. However, according to the configuration in which the entire bottom surface portion 121a is configured as a laminate as in this embodiment, and the bottom surface portion 121a is arranged in the recess 121c of the peripheral wall portion 121b, the structure of the bottom surface portion 121a becomes complicated. Moreover, the bottom surface portion 121a and the peripheral wall portion 121b can be fixed with high positional accuracy.
• the number of magnetic metal plates 122 on the bottom surface portion 121a can be changed as appropriate.
• the thickness of the bottom portion 121a does not necessarily have to be the same as that of the pole piece 25 and the ring yoke 27.
• FIG. 7 is a sectional view showing the configuration of a modification of the second embodiment.
• the yoke main body 121' has a bottom part 121a and a peripheral wall part 121b', and both of the bottom part 121a and the peripheral wall part 121b' have a plurality of magnetic metal plates mutually connected to each other. It is provided as a laminate that is stacked in an electrically insulated state.
• the bottom portion 121a is basically the same as the configuration shown in FIGS. 5 and 6, but in the configuration of FIG. 7, the diameter of the bottom portion 121a is slightly larger than that of the configuration shown in FIGS. 5 and 6. It is formed.
• the peripheral wall portion 121b has a structure in which a plurality of annular magnetic metal plates are laminated in the thickness direction of the permanent magnet 23. The magnetic metal plates of the peripheral wall portion 121b are fixed to each other using, for example, an anaerobic adhesive, as in the embodiment described above.
• peripheral wall portion 121b' is also constituted by a laminate in which magnetic metal plates are laminated, the eddy current is further reduced compared to the configuration of the above embodiment, and the loss of driving force is reduced. be able to.
• the present invention requires that all members of the pole piece, ring yoke, and yoke body be configured as a laminate. There isn't.
• at least one of the pole piece, the ring yoke, and the yoke body is composed of a laminate in which a plurality of magnetic metal plates are laminated in the thickness direction of the permanent magnet while being electrically insulated from each other. That's fine.

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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)

Priority Applications (4)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (1)

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ID=88518324

Family Applications (1)

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Citations (4)

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• 2023
  • 2023-01-11 JP JP2024517834A patent/JPWO2023210065A1/ja active Pending
  • 2023-01-11 CN CN202380021139.1A patent/CN118679758A/zh active Pending
  • 2023-01-11 EP EP23795814.5A patent/EP4472237A4/en active Pending
  • 2023-01-11 WO PCT/JP2023/000375 patent/WO2023210065A1/ja not_active Ceased
• 2024
  • 2024-08-09 US US18/799,279 patent/US20240406637A1/en active Pending

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