WO2013145227A1 - Magnetic circuit for speaker device and speaker device - Google Patents

Magnetic circuit for speaker device and speaker device Download PDF

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Publication number
WO2013145227A1
WO2013145227A1 PCT/JP2012/058432 JP2012058432W WO2013145227A1 WO 2013145227 A1 WO2013145227 A1 WO 2013145227A1 JP 2012058432 W JP2012058432 W JP 2012058432W WO 2013145227 A1 WO2013145227 A1 WO 2013145227A1
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WO
WIPO (PCT)
Prior art keywords
magnet
speaker device
magnetic circuit
plate
magnetic
Prior art date
Application number
PCT/JP2012/058432
Other languages
French (fr)
Japanese (ja)
Inventor
真祐 小沼
古頭　晶彦
Original Assignee
パイオニア株式会社
東北パイオニア株式会社
Priority date (The priority date 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 date listed.)
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Application filed by パイオニア株式会社, 東北パイオニア株式会社 filed Critical パイオニア株式会社
Priority to PCT/JP2012/058432 priority Critical patent/WO2013145227A1/en
Publication of WO2013145227A1 publication Critical patent/WO2013145227A1/en

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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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0273—Magnetic circuits with PM for magnetic field generation
    • H01F7/0289—Transducers, loudspeakers, moving coil arrangements
    • 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
    • H04R2209/022—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 circuit for a speaker device and a speaker device.
  • Current mainstream speaker devices emit sound by vibrating the diaphragm.
  • the vibration of the diaphragm is generated in conjunction with the vibration of the voice coil connected to the diaphragm.
  • the voice coil is disposed in a magnetic gap formed in a magnetic circuit for a speaker device (hereinafter also referred to as “magnetic circuit”).
  • magnetic circuit for a speaker device
  • a magnetic circuit that applies a driving force to a voice coil is required to increase the magnetic flux density Bg of the magnetic gap with a small amount of magnet (weight or volume).
  • a magnetic circuit is configured using two types of magnets: a ferrite magnet main magnet and a neodymium magnet first and second sub-magnet.
  • the magnetic circuit of Patent Document 1 combines the magnetic flux generated by the magnetomotive force of the main magnet and the magnetic flux repelled by the magnetomotive force of the first and second submagnets at the magnetic gap, thereby obtaining the magnetic flux density Bg in the magnetic gap. It is increasing.
  • Patent Document 1 it is difficult for the ferrite magnet used for the main magnet of Patent Document 1 to increase the magnetic flux density at the operating point from the demagnetization curve representing the performance of the magnet. For this reason, in a magnetic circuit using a ferrite magnet, the magnetic flux density Bg of the magnetic gap cannot be increased unless the cross-sectional area of the magnet is increased. Therefore, in patent document 1, the diameter of a main magnet must be enlarged, and the weight and cost of a main magnet will increase. In other words, in Patent Document 1, it is necessary to increase the amount (weight and volume) of a magnet necessary for obtaining a desired magnetic flux density Bg with a magnetic gap, and the use efficiency of the magnet is poor. Further, in Patent Document 1, as the diameter of the main magnet is increased, the magnetic circuit including the yoke and the plate is increased in size, weight, and cost.
  • Patent Document 1 Furthermore, the neodymium magnets used for the first and second submagnets of Patent Document 1 are very expensive. In addition, in Patent Document 1, a magnetic circuit is configured using a plurality of magnets. For this reason, in patent document 1, a cost increase will be caused with the use of an expensive member called a neodymium magnet and an increase in the number of parts.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-described problems. That is, the present invention provides an inexpensive magnetic circuit for a speaker device and a speaker device that are small in diameter and light in weight, and that can achieve both the efficiency of using a magnet and the magnetic flux density.
  • a magnetic circuit for a speaker device includes a Fe—Cr—Co based magnet, a plate provided on one pole side of the magnet, a yoke provided on the other pole side of the magnet, A magnetic circuit for a speaker device having at least a magnetic gap formed between the plate and the yoke.
  • a speaker device includes the magnetic circuit for a speaker device according to any one of the first to third aspects, wherein the voice coil disposed in the magnetic gap and the voice coil are wound. And a diaphragm connected to the voice coil bobbin.
  • FIG. 1 is a schematic diagram of a speaker device 1 according to an embodiment of the present invention.
  • the speaker device 1 of FIG. 1 has a low profile substantially truncated cone shape with the sound emission direction as a central axis.
  • the axial direction of the speaker device 1 is the vertical direction of the paper surface
  • the radial direction of the speaker device 1 is the horizontal direction of the paper surface, the near side, and the depth direction.
  • the sound emission direction of the speaker device 1 is assumed to be upward.
  • the speaker device 1 includes at least a diaphragm 10, a voice coil 20, a frame 30, and a magnetic circuit 100.
  • the diaphragm 10 radiates sound by mechanically vibrating in the axial direction.
  • the vibration of the diaphragm 10 is interlocked with the reciprocating motion of the voice coil 20 in the axial direction.
  • the diaphragm 10 is formed in a substantially disc shape using a metal material, a resin material, a fiber material, or a mixed material thereof.
  • the central axis of the substantially disc shape is substantially the same as the axial direction of the speaker device 1.
  • the diaphragm 10 in FIG. 1 includes a vibration part 11, a damper part 12, and an edge part 13.
  • the vibration part 11, the damper part 12, and the edge part 13 are integrally formed.
  • the vibration part 11 is a main body part of the diaphragm 10 and can vibrate in the axial direction.
  • the diaphragm 10 radiates a sound wave generated by the vibration of the vibration unit 11 upward.
  • the vibration part 11 has a dome shape convex upward, and is formed at the center of the vibration plate 10.
  • the vibration unit 11 in FIG. 1 has a substantially semicircular cross-sectional view, but may have a substantially parabolic shape, a substantially conical shape, a substantially multi-stage curve shape, or the like.
  • a voice coil bobbin 21 around which a voice coil 20 that drives the vibration of the diaphragm 10 is wound is connected to the back side of the outer periphery of the vibration unit 11 (opposite to the sound radiation direction) so as to vibrate in the axial direction. Yes.
  • the damper portion 12 regulates the radial vibration of the diaphragm 10 and holds the axial vibration center.
  • the damper portion 12 has a substantially arc shape that is convex upward in cross-sectional view, and is formed on the outer periphery of the vibration portion 11.
  • the edge portion 13 spans the diaphragm 10 to the frame 30.
  • the edge portion 13 regulates and controls the vibration of the diaphragm 10 together with the damper portion 12.
  • the edge portion 13 blocks sound on the back side of the diaphragm 10 (on the side opposite to the sound emission direction).
  • the edge portion 13 has a substantially linear shape with a cross-sectional view extending in the radial direction, is formed on the outer periphery of the damper portion 12, and is fixed to the frame 30.
  • the voice coil 20 is a driving source for vibration of the diaphragm 10.
  • the voice coil 20 is wound around the outer periphery of a voice coil bobbin 21 whose central axis has a substantially cylindrical shape in the axial direction.
  • the central axis of the voice coil 20 is the axial direction and is substantially the same as the central axis of the voice coil bobbin 21.
  • the place where the voice coil 20 is wound is the end of the voice coil bobbin 21 on the lower side (the direction opposite to the sound radiation direction).
  • the winding direction of the voice coil 20 is substantially orthogonal to the direction (axial direction) in which the central axis of the voice coil bobbin 21 formed in a substantially cylindrical shape extends.
  • the width direction of the winding width of the voice coil 20 (increase direction of the winding width) is substantially parallel to the direction (axial direction) in which the central axis of the voice coil bobbin 21 extends.
  • the diaphragm 10 is connected to the upper end (sound radiation direction side) of the voice coil bobbin 21.
  • the voice coil 20 is disposed in the magnetic gap G of the magnetic circuit 100.
  • the magnetic gap G is formed between a plate 110 (described later) of the magnetic circuit 100 and a yoke 120.
  • the voice coil 20 arranged in the magnetic gap G has the following positional relationship with the plate 110. Specifically, the central position in the axial direction of the winding width of the voice coil 20 and the central position of the thickness in the axial direction of the plate 110 have substantially the same positional relationship (see an enlarged view of the main part in FIG. 1). reference).
  • the axial direction is substantially parallel to the magnetization direction of the magnet 130 as will be described later. That is, the voice coil 20 is arranged so that the center position of the winding width in the magnetization direction is substantially the same as the center position of the thickness in the magnetization direction of the plate 110.
  • the voice coil 20 is connected to a speaker amplifier (not shown) via a lead wire.
  • a voice current is supplied to the voice coil 20 from the speaker amplifier.
  • the voice coil 20 receives an electromagnetic force due to the interaction between the magnetic flux of the magnetic gap G and the current.
  • the voice coil 20 receiving the electromagnetic force reciprocates in the axial direction within the magnetic gap G using the electromagnetic force as a driving force.
  • the voice coil 20 that reciprocates in the axial direction vibrates the diaphragm 10 connected to the voice coil bobbin 21 in the axial direction. In this way, the voice coil 20 converts the supplied audio current into mechanical vibration and gives the diaphragm 10 an axial driving force.
  • the frame 30 is a skeleton of the speaker device 1 and supports the diaphragm 10 and the magnetic circuit 100.
  • the frame 30 is formed of a metal material in a substantially annular shape with a central axis in the axial direction.
  • the frame 30 has a bent portion 31 having a lower portion as a base end and a distal end bent and extended radially inward.
  • a flat portion 32 is provided on the upper surface side of the bent portion 31.
  • the edge portion 13 of the diaphragm 10 is fixed to the flat portion 32.
  • a yoke 120 described later of the magnetic circuit 100 is fixed to the tip of the bent portion 31.
  • FIG. 2 is a schematic diagram of a magnetic circuit 100 according to an embodiment of the present invention.
  • the magnetic circuit 100 forms a magnetic gap G that can accommodate the voice coil 20, and supplies magnetic flux necessary for vibration of the voice coil 20.
  • the magnetic circuit 100 is a so-called inner magnet type magnetic circuit for a speaker device.
  • the magnetic circuit 100 includes a plate 110, a yoke 120, and a magnet 130.
  • the magnetic circuit 100 has a structure in which a yoke 120, a magnet 130, and a plate 110 are stacked in order from the bottom to the top.
  • the thickness of the magnet 130 in the magnetization direction is expressed as Lm
  • the thickness of the plate 110 in the magnetization direction is expressed as Lp.
  • the plate 110 forms one end of the magnetic path of the magnetic circuit 100 and the magnetic gap G.
  • the plate 110 is made of a magnetic material such as iron and has a substantially cylindrical shape with a central axis in the axial direction.
  • the central axis of the substantially cylindrical plate 110 is substantially the same as the central axis of the voice coil 20 and the voice coil bobbin 21. That is, the plate 110 is substantially concentric with the voice coil 20 and the voice coil bobbin 21.
  • the outer diameter of the plate 110 is smaller than the inner diameter of the voice coil 20 and the voice coil bobbin 21.
  • the thickness Lp of the plate 110 is substantially uniform.
  • the bottom surface (lower surface) on the lower side of the plate 110 is magnetically bonded to one pole side (for example, the S pole side) of the magnet 130.
  • the magnetic flux supplied from the magnet 130 passes through the plate 110.
  • the outer peripheral surface 111 of the plate 110 is substantially parallel to the central axis of the voice coil 20 and the voice coil bobbin 21.
  • An outer peripheral surface 111 of the plate 110 faces an inner peripheral surface 123 of a yoke 120 described later, and forms one end of the magnetic gap G.
  • the yoke 120 forms one end of the magnetic path of the magnetic circuit 100 and the magnetic gap G.
  • the yoke 120 has a substantially disc-shaped bottom 121 having a central axis in the axial direction, and a substantially cylindrical side 122 having a distal end extending substantially parallel to the axial direction with the outer periphery of the bottom 121 as a base end. .
  • the central axes of the substantially disc-shaped bottom portion 121 and the substantially cylindrical side portion 122 are substantially the same as the central axes of the voice coil 20 and the voice coil bobbin 21.
  • the bottom part 121 and the side part 122 are formed using magnetic materials, such as iron, and are integrally molded.
  • the outer diameter of the bottom part 121 and the inner diameter of the side part 122 are larger than the outer diameters of the voice coil 20 and the voice coil bobbin 21.
  • the thickness of the bottom part 121 and the side part 122 is substantially uniform.
  • the upper surface of the bottom 121 is magnetically joined to the other pole side of the magnet 130 (the side different from the magnetic pole joined to the plate 110, for example, the N pole side).
  • the magnetic flux supplied from the magnet 130 passes through the yoke 120.
  • the end surface of the extending tip of the side portion 122 is substantially at the same height as the upper bottom surface (upper surface) of the plate 110. That is, the end surface of the extending tip of the side portion 122 is substantially on the same plane as the bottom surface of the plate 110 located on the side opposite to the magnet 130.
  • the extension length at the extension tip of the side portion 122 is substantially equal to the sum of the thickness Lm of the magnet 130 and the thickness Lp of the plate 110.
  • the inner peripheral surface 123 at the tip of the side portion 122 is substantially parallel to the central axis of the voice coil 20 and the voice coil bobbin 21.
  • An inner peripheral surface 123 at the tip of the side portion 122 faces the outer peripheral surface 111 of the plate 110 substantially in parallel, and forms one end of the magnetic gap G.
  • the magnetic gap G is formed between the outer peripheral surface 111 of the plate 110 and the inner peripheral surface 123 of the yoke 120 facing each other substantially parallel to each other, and has a substantially cylindrical shape whose central axis is the axial direction.
  • the inner diameter of the substantially cylindrical magnetic gap G corresponds to the outer diameter of the plate 110.
  • the outer diameter of the substantially cylindrical magnetic gap G corresponds to the inner diameter of the yoke 120.
  • the voice coil 20 wound around the voice coil bobbin 21 is disposed in the magnetic gap G.
  • the magnet 130 supplies magnetic flux to the magnetic circuit 100, particularly to the magnetic gap G.
  • the magnet 130 is formed in a substantially cylindrical shape whose central axis is the axial direction.
  • the central axis of the substantially cylindrical magnet 130 is substantially the same as the central axes of the voice coil 20, the voice coil bobbin 21, the plate 110, and the yoke 120 (the bottom 121 and the side 122). That is, the magnet 130 is substantially concentric with the voice coil 20, the voice coil bobbin 21, the plate 110, and the yoke 120 (the bottom portion 121 and the side portion 122).
  • the outer diameter of the magnet 130 is the same as or smaller than the outer diameter of the plate 110.
  • the side surface of the magnet 130 does not contact the voice coil 20 disposed in the magnetic gap G.
  • the thickness Lm of the magnet 130 is substantially uniform.
  • the upper bottom surface (upper surface) and the lower bottom surface (lower surface) of the magnet 130 have different magnetic poles to form a pair of magnetic poles.
  • the magnetization direction of the magnet 130 is a direction from one side to the other side of each bottom surface of the magnet 130 (a direction from the upper surface to the lower surface or from the lower surface to the upper surface), and is substantially parallel to the axial direction. That is, the magnetization direction of the magnet 130 is the thickness direction of the magnet 130, the thickness direction of the plate 110, the direction in which the side portion 122 of the yoke 120 extends, the direction in which the central axis of the voice coil bobbin 21 extends, and the voice It is substantially parallel to the width direction of the winding width of the coil 20 and the like.
  • the upper bottom surface (upper surface) of the magnet 130 having one magnetic pole (for example, the S pole) is magnetically joined to the lower bottom surface (lower surface) of the plate 110.
  • the bottom surface (lower surface) on the lower side of the magnet 130 having the other magnetic pole (for example, N pole) is magnetically joined to the upper surface of the bottom 121 constituting the yoke 120.
  • the magnetic circuit 100 is provided with the outer peripheral surface 111 forming the magnetic gap G and the inner peripheral surface 123 facing each other substantially in parallel.
  • the outer peripheral surface 111 and the inner peripheral surface 123 are substantially parallel to the direction of the audio current supplied to the voice coil 20 and the direction in which the voice coil 20 can reciprocate. Therefore, the direction of the magnetic flux supplied to the magnetic gap G is substantially orthogonal to the direction of the audio current supplied to the voice coil 20 and the direction in which the voice coil 20 can reciprocate. For this reason, in the magnetic circuit 100, the electromagnetic force generated by the interaction between the magnetic flux in the magnetic gap G and the sound current can be efficiently applied to the voice coil 20.
  • the magnetic circuit 100 is a so-called inner-magnet type speaker device magnetic circuit.
  • the magnetic circuit for the speaker device of the internal magnet type is a circuit in which the magnet is arranged radially inward from the magnetic gap.
  • the magnetic circuit for the speaker device of the outer magnet type is a magnetic circuit in which the magnet is arranged radially outside the magnetic gap.
  • the design specifications of the voice coil are often predetermined in order to achieve the desired sound range characteristics. Therefore, the inner and outer diameter dimensions of the magnetic gap are often restricted in advance. In this case, since the magnet circuit for the inner-magnet type speaker device has the magnet arranged radially inside the magnetic gap, the diameter of the magnet can be made smaller than that of the outer-magnet type.
  • the magnetic circuit 100 which is an internal magnet type speaker circuit magnetic circuit
  • the diameter of the magnet 130 can be reduced.
  • the whole magnetic circuit including the plate 110 and the yoke 120 can be reduced in size. Therefore, the magnetic circuit 100 can reduce the weight and cost of the magnetic circuit.
  • the speaker device 1 having the magnetic circuit 100 can also be reduced in size, weight, and cost.
  • an Fe—Cr—Co (iron-chromium-cobalt) -based magnet is used as the magnet 130 which is a main member of the magnetic circuit 100.
  • Fe-Cr-Co magnets have better reverse temperature characteristics than ferrite magnets, and the amount of demagnetization due to temperature rise is small.
  • FIG. 3 is a diagram for explaining the magnetic characteristics of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
  • the vertical axis in FIG. 3 is the magnetic flux density B of the magnet, and the horizontal axis in FIG. 3 is the magnetic field strength H.
  • the curve in FIG. 3 is a demagnetization curve of an Fe—Cr—Co based magnet that is a constituent material of the magnet 130.
  • the intercept with the vertical axis of the demagnetization curve indicates the residual magnetic flux density Br, and the intercept with the horizontal axis of the demagnetization curve indicates the coercive force Hcb.
  • the demagnetization curve is the second quadrant of the magnetization curve (BH curve) and indicates the magnetic characteristics of the magnet.
  • the magnetic flux density Bg of the magnetic gap G depends on the magnetic flux density Bd at the operating point d of the magnet 130 included in the magnetic circuit 100. In order to increase the magnetic flux density Bg of the magnetic gap G, it is necessary to increase the magnetic flux density Bd at the operating point d of the magnet 130.
  • the operating point d of the magnet 130 can be obtained from the permeance coefficient Pc of the magnet 130 and the demagnetization curve.
  • the permeance coefficient Pc indicates the ease of supplying the magnetic flux from the magnet to the outside, and depends on the shape of the magnet 130 and the magnetic gap G.
  • the operating point d of the magnet 130 corresponds to the intersection of a permeance straight line (a straight line passing through the origin of the demagnetization curve with the product of the permeance coefficient Pc and the vacuum permeability ⁇ 0 as an inclination) and the demagnetization curve.
  • a permeance straight line a straight line passing through the origin of the demagnetization curve with the product of the permeance coefficient Pc and the vacuum permeability ⁇ 0 as an inclination
  • the permeance coefficient Pc increases, the slope of the permeance straight line increases.
  • the position of the operating point d approaches the residual magnetic flux density Br on the demagnetization curve.
  • the maximum value of the magnetic flux density Bd at the operating point d is the residual magnetic flux density Br of the demagnetization curve.
  • the constituent material of the magnet 130 needs to be a material having a demagnetization curve with a large residual magnetic flux density Br.
  • the shape of the magnet 130 and the magnetic gap G needs to be a shape having a high permeance coefficient Pc.
  • the residual magnetic flux density Br of the Fe—Cr—Co based magnet that is a constituent material of the magnet 130 is significantly larger than the residual magnetic flux density Br of the ferrite based magnet. Therefore, if the shape of the magnet 130 and the magnetic gap G is a shape having a high permeance coefficient Pc, the magnetic flux density Bd at the operating point d can be increased. If the magnetic flux density Bd at the operating point d can be increased, the magnetic flux density Bg at the magnetic gap G can be increased.
  • the relationship between the magnetic flux density B and the magnetic field strength H is not linear and has a bending point K as shown in FIG.
  • the bending point K is a point where the gradient of the demagnetization curve changes greatly.
  • the steep gradient is due to the great effect of reducing the magnetization M of the magnet 130 by the demagnetizing field Hd in the magnet 130.
  • the reason why the gradient is gentle is that the action of lowering the magnetization M of the magnet 130 by the demagnetizing field Hd in the magnet 130 is small.
  • the action of reducing the magnetization M by the demagnetizing field Hd is small, so that the magnetic flux density Bd can be increased.
  • the strength of the demagnetizing field Hd depends on the shape of the magnet 130 and the magnetic gap G.
  • the shape of the magnet 130 and the magnetic gap with a small demagnetizing field Hd is a shape with a high permeance coefficient Pc. Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a high permeance coefficient Pc so that the operating point d is positioned on the residual magnetic flux density Br side from the bending point K.
  • the magnet 130 is affected by an external magnetic field such as an alternating magnetic field generated by driving the voice coil 20.
  • the operating point d fluctuates.
  • the magnetic flux density Bd hardly changes even if the operating point d varies. If the magnetic flux density Bd hardly changes, the magnetic flux density Bg of the magnetic gap G is stabilized. Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a high permeance coefficient Pc so that the operating point d is positioned on the residual magnetic flux density Br side from the bending point K.
  • the energy product (Bd ⁇ Hd) at the operating point d of the magnet 130 is proportional to the magnetic energy per unit volume that the magnet 130 can supply to the outside.
  • the use efficiency of the magnet 130 is better when the energy product of the operating point d is larger.
  • the maximum energy product (BHmax) of the magnet 130 is an energy product near the bending point K. Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a permeance coefficient Pc such that the operating point d is positioned in the vicinity of the bending point K.
  • the shapes of the magnet 130 and the magnetic gap G are designed as follows. That's fine. That is, if the shapes of the magnet 130 and the magnetic gap G are designed so that the operating point d is located on the side of the residual magnetic flux density Br from the bending point K and in the vicinity of the bending point K, the permeance coefficient Pc. Good.
  • the permeance coefficient Pc increases as the thickness Lm in the magnetization direction of the magnet 130 and the cross-sectional area of the magnetic gap G are increased.
  • the magnetic flux density Bg of the magnetic gap G decreases.
  • the cross-sectional area of the magnetic gap G depends on the thickness Lp of the plate 110 and the diameter of the plate 110. The diameter of the plate 110 is often constrained in advance by the design specifications of the voice coil 20. For this reason, attention is paid to the thickness Lp of the plate 110 having a high degree of design freedom.
  • the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 should be optimized. Good.
  • FIG. 4 is a graph showing the magnetic flux density Bg of the magnetic gap G included in the magnetic circuit 100 according to the embodiment of the present invention.
  • the vertical axis in FIG. 4 is the magnetic flux density Bg of the magnetic gap G
  • the horizontal axis in FIG. 4 is the thickness Lm of the magnet 130.
  • the curve in FIG. 4 shows the relationship between the thickness Lm of the magnet 130 and the magnetic flux density Bg when the thickness Lm of the magnet 130 is changed for each thickness Lp of the plate 110.
  • the magnetic flux density Bg increases substantially linearly with the same transition regardless of the thickness Lp of the plate 110.
  • the magnetic flux density Bg shows different transitions for each thickness Lp of the plate 110. At this time, the transition of the magnetic flux density Bg becomes a lower transition as the thickness Lp of the plate 110 is larger.
  • the use efficiency of the magnet 130 is improved.
  • FIG. 5 is a graph showing the permeance coefficient Pc of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
  • the vertical axis in FIG. 5 is the permeance coefficient Pc of the magnet 130
  • the horizontal axis in FIG. 5 is the thickness Lm of the magnet 130.
  • the curve in FIG. 5 shows the relationship between the thickness Lm of the magnet 130 and the permeance coefficient Pc of the magnet 130 when the thickness Lm of the magnet 130 is changed for each thickness Lp of the plate 110.
  • the permeance coefficient Pc increases approximately linearly with different transitions for each thickness Lp of the plate 110.
  • the transition of the permeance coefficient Pc increases as the thickness Lp of the plate 110 increases.
  • the thickness Lm of the magnet 130 may be increased. However, as shown in FIG. 4, when the thickness Lm of the magnet 130 is larger than the points A to D at which the magnetic flux density Bg saturates, the increase in the thickness Lm of the magnet 130 increases the magnetic flux density Bg of the magnetic gap G. Hard to contribute.
  • FIG. 5 plots points A to D where the magnetic flux density Bg shown in FIG. 4 is saturated.
  • FIG. 6 is a diagram for explaining the operating point d of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
  • the curve in FIG. 6 is a demagnetization curve of an Fe—Cr—Co based magnet that is a constituent material of the magnet 130, and is the same as the demagnetization curve in FIG.
  • the curve in FIG. 6 shows the relationship between the permeance coefficient Pc shown in FIG. 5 and the demagnetization curve shown in FIG.
  • the operating point d of the magnet 130 is located on the residual magnetic flux density Br side from the bending point K, and It is located in the vicinity of the point K.
  • Pc 18 or more and 22 or less are suitable.
  • FIG. 7 is a graph showing the relationship between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 included in the magnetic circuit 100 according to the embodiment of the present invention.
  • the vertical axis in FIG. 7 is the thickness Lm of the magnet 130
  • the horizontal axis in FIG. 7 is the thickness Lp of the plate 110.
  • the relationship between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is substantially inversely proportional.
  • the possible range of the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is at least a range S (see FIG. 7).
  • the operating point d of the magnet 130 is closer to the residual magnetic flux density Br than the bending point K and the bending point. It can be located near K.
  • the magnetic flux density Bd is high and the use efficiency of the magnet is high. That is, when the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are at least points in the range S, the amount of magnets necessary to obtain the desired magnetic flux density Bg can be minimized. Therefore, in the magnetic circuit 100 having the magnet 130 having the above magnetic characteristics, in order to achieve both the use efficiency of the magnet and the magnetic flux density Bg, the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are set to at least the range S. What is necessary is just to be a point inside.
  • both the magnet use efficiency and the magnetic flux density Bg are compatible. Can be achieved.
  • Lm: Lp 1: 1 to 3: 1.
  • the inner-magnet-type magnetic circuit 100 is configured using the magnet 130 made of a Fe—Cr—Co-based magnet.
  • the ratio between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is optimized.
  • the magnetic circuit 100 of the present embodiment can reduce the diameter and weight of the magnet without using an expensive magnet such as a neodymium magnet, and can achieve a desired magnetic flux density with a magnet with high use efficiency. Bg can be obtained. Therefore, according to this embodiment, it is possible to provide an inexpensive magnetic circuit 100 that is small in diameter and light in weight, and that can achieve both the use efficiency of the magnet and the magnetic flux density.
  • the speaker apparatus 1 carrying such a small, high performance, and inexpensive magnetic circuit 100 can be provided.
  • the speaker device 1 is a so-called dome-shaped speaker device in which the diaphragm 10 has a shape.
  • the speaker device 1 may be a cone speaker device, a horn speaker device, a flat speaker device, a flat speaker device, or a Heil speaker device.
  • the diaphragm 10 is formed of a metal material, a resin material, a fiber material, or a mixed material thereof.
  • the metal material forming the diaphragm 10 is, for example, aluminum, titanium, beryllium, magnesium, boron, or an alloy thereof.
  • the resin material forming the diaphragm 10 is, for example, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, epoxy, or the like.
  • the fiber material forming the diaphragm 10 is, for example, a mixed fiber of sulfite pulp or kraft pulp.
  • the vibration part 11, the damper part 12, and the edge part 13 of the diaphragm 10 are integrally formed.
  • the damper portion 12 and the edge portion 13 may be formed of a separate material different from the vibrating portion 11.

Abstract

Provided are an inexpensive magnetic circuit for a speaker device and a speaker device, the magnetic circuit having a small diameter and a light weight and capable of achieving both the magnet use efficiency and the magnetic flux density. A magnetic circuit (100) used for a speaker device (1) comprises: a magnet (130), a plate (110) provided on one pole side of the magnet (130); a yoke (120) provided on the other pole side of the magnet (130); and a magnetic gap (G) formed between the plate (110) and the yoke (120). The magnet (130) is an Fe-Cr-Co-based magnet.

Description

スピーカー装置用磁気回路及びスピーカー装置Magnetic circuit for speaker device and speaker device
　本発明は、スピーカー装置用磁気回路及びスピーカー装置に関する。 The present invention relates to a magnetic circuit for a speaker device and a speaker device.
　現在主流のスピーカー装置は、振動板を振動させて音を放射する。振動板の振動は、振動板に接続されたボイスコイルの振動に連動して発生する。ボイスコイルは、スピーカー装置用磁気回路（以下、「磁気回路」ともいう）に形成された磁気ギャップ内に配置されている。磁気ギャップで磁束を得たボイスコイルは、電流が供給されると、発生する電磁力を駆動力として振動する。ボイスコイルに駆動力を与える磁気回路には、少ない磁石量（重量や体積）で磁気ギャップの磁束密度Ｂｇを高めることが求められている。 現在 Current mainstream speaker devices emit sound by vibrating the diaphragm. The vibration of the diaphragm is generated in conjunction with the vibration of the voice coil connected to the diaphragm. The voice coil is disposed in a magnetic gap formed in a magnetic circuit for a speaker device (hereinafter also referred to as “magnetic circuit”). When a current is supplied, the voice coil that has obtained magnetic flux through the magnetic gap vibrates using the generated electromagnetic force as a driving force. A magnetic circuit that applies a driving force to a voice coil is required to increase the magnetic flux density Bg of the magnetic gap with a small amount of magnet (weight or volume).
　例えば、特許文献１では、フェライト系磁石のメインマグネットと、ネオジム系磁石の第１及び第２サブマグネットとの２種類の磁石を用いて磁気回路を構成している。特許文献１の磁気回路は、メインマグネットの起磁力による磁束と、第１及び第２サブマグネットの起磁力で反発する磁束とを、磁気ギャップで合成することによって、磁気ギャップでの磁束密度Ｂｇを高めている。 For example, in Patent Document 1, a magnetic circuit is configured using two types of magnets: a ferrite magnet main magnet and a neodymium magnet first and second sub-magnet. The magnetic circuit of Patent Document 1 combines the magnetic flux generated by the magnetomotive force of the main magnet and the magnetic flux repelled by the magnetomotive force of the first and second submagnets at the magnetic gap, thereby obtaining the magnetic flux density Bg in the magnetic gap. It is increasing.
特開２００６－２０１３９号公報JP 2006-20139 A
　しかしながら、特許文献１のメインマグネットに用いるフェライト系磁石は、磁石の性能を表す減磁曲線から、動作点での磁束密度を高くすることが困難である。このため、フェライト系磁石を用いた磁気回路では、磁石の断面積を大きくしないと、磁気ギャップの磁束密度Ｂｇを高めることができない。
　ゆえに、特許文献１では、メインマグネットの直径を大径化せざるを得ず、メインマグネットの重量及びコストが増加してしまう。言い換えると、特許文献１では、磁気ギャップで所望の磁束密度Ｂｇを得るために必要な磁石の量（重量や体積）を多くせざるを得ず、磁石の使用効率が悪い。
　また、特許文献１では、メインマグネットの大径化に伴い、ヨーク及びプレートを含む磁気回路の大型化、重量化、及びコスト増加も招いてしまう。 However, it is difficult for the ferrite magnet used for the main magnet of Patent Document 1 to increase the magnetic flux density at the operating point from the demagnetization curve representing the performance of the magnet. For this reason, in a magnetic circuit using a ferrite magnet, the magnetic flux density Bg of the magnetic gap cannot be increased unless the cross-sectional area of the magnet is increased.
Therefore, in patent document 1, the diameter of a main magnet must be enlarged, and the weight and cost of a main magnet will increase. In other words, in Patent Document 1, it is necessary to increase the amount (weight and volume) of a magnet necessary for obtaining a desired magnetic flux density Bg with a magnetic gap, and the use efficiency of the magnet is poor.
Further, in Patent Document 1, as the diameter of the main magnet is increased, the magnetic circuit including the yoke and the plate is increased in size, weight, and cost.
　更に、特許文献１の第１及び第２サブマグネットに用いるネオジム系磁石は、非常に高価である。加えて、特許文献１では、複数の磁石を用いて磁気回路を構成している。
　このため、特許文献１では、ネオジム系磁石という高価な部材の使用、及び、部品点数の増加に伴って、コスト増加を招いてしまう。 Furthermore, the neodymium magnets used for the first and second submagnets of Patent Document 1 are very expensive. In addition, in Patent Document 1, a magnetic circuit is configured using a plurality of magnets.
For this reason, in patent document 1, a cost increase will be caused with the use of an expensive member called a neodymium magnet and an increase in the number of parts.
　本発明は、上記事情に鑑みてなされたものであり、上述のような問題点を解決することを課題の一例とするものである。すなわち、本発明は、小径且つ軽量であり、磁石の使用効率及び磁束密度の両立が可能である安価なスピーカー装置用磁気回路及びスピーカー装置を提供する。 The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-described problems. That is, the present invention provides an inexpensive magnetic circuit for a speaker device and a speaker device that are small in diameter and light in weight, and that can achieve both the efficiency of using a magnet and the magnetic flux density.
　本発明の請求項１に係るスピーカー装置用磁気回路は、Ｆｅ－Ｃｒ－Ｃｏ系磁石と、前記磁石の一極側に設けられたプレートと、前記磁石の他極側に設けられたヨークと、前記プレートと前記ヨークとの間に形成された磁気ギャップと、を少なくとも有するスピーカー装置用磁気回路である。 A magnetic circuit for a speaker device according to claim 1 of the present invention includes a Fe—Cr—Co based magnet, a plate provided on one pole side of the magnet, a yoke provided on the other pole side of the magnet, A magnetic circuit for a speaker device having at least a magnetic gap formed between the plate and the yoke.
　本発明の請求項１５に係るスピーカー装置は、請求項１乃至３のいずれかに記載のスピーカー装置用磁気回路を有し、前記磁気ギャップ内に配置されたボイスコイルと、前記ボイスコイルが巻回されたボイスコイルボビンと、前記ボイスコイルボビンに接続された振動板と、を有するスピーカー装置である。 A speaker device according to a fifteenth aspect of the present invention includes the magnetic circuit for a speaker device according to any one of the first to third aspects, wherein the voice coil disposed in the magnetic gap and the voice coil are wound. And a diaphragm connected to the voice coil bobbin.
本発明の一実施形態に係るスピーカー装置の概略図である。It is the schematic of the speaker apparatus which concerns on one Embodiment of this invention. 本発明の一実施形態に係る磁気回路の概略図である。It is the schematic of the magnetic circuit which concerns on one Embodiment of this invention. 本発明の一実施形態に係る磁気回路が有する磁石の磁気特性を説明するための図である。It is a figure for demonstrating the magnetic characteristic of the magnet which the magnetic circuit which concerns on one Embodiment of this invention has. 本発明の一実施形態に係る磁気回路が有する磁気ギャップの磁束密度を示すグラフである。It is a graph which shows the magnetic flux density of the magnetic gap which the magnetic circuit which concerns on one Embodiment of this invention has. 本発明の一実施形態に係る磁気回路が有する磁石のパーミアンス係数を示すグラフである。It is a graph which shows the permeance coefficient of the magnet which the magnetic circuit concerning one embodiment of the present invention has. 本発明の一実施形態に係る磁気回路が有する磁石の動作点を説明するための図である。It is a figure for demonstrating the operating point of the magnet which the magnetic circuit which concerns on one Embodiment of this invention has. 本発明の一実施形態に係る磁気回路が有する磁石の厚さとプレートの厚さとの関係を示すグラフである。It is a graph which shows the relationship between the thickness of the magnet which the magnetic circuit which concerns on one Embodiment of this invention has, and the thickness of a plate.
　以下、本発明を実施するための形態について、図面を参照しながら説明する。
　図１は、本発明の一実施形態に係るスピーカー装置１の概略図である。図１では、スピーカー装置１の音放射方向で破断した縦断面構造を示している。
　図１のスピーカー装置１は、音放射方向を中心軸とする低背の略円錐台形形状をしている。図１では、スピーカー装置１の軸方向を紙面の上下方向とし、スピーカー装置１の径方向を紙面の左右方向並びに手前及び奥行き方向とする。図１では、スピーカー装置１の音放射方向を上方とする。図２以降も同様とする。
　スピーカー装置１は、振動板１０と、ボイスコイル２０と、フレーム３０と、磁気回路１００とを少なくとも有する。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a speaker device 1 according to an embodiment of the present invention. In FIG. 1, the longitudinal cross-sectional structure fractured | ruptured in the sound radiation direction of the speaker apparatus 1 is shown.
The speaker device 1 of FIG. 1 has a low profile substantially truncated cone shape with the sound emission direction as a central axis. In FIG. 1, the axial direction of the speaker device 1 is the vertical direction of the paper surface, and the radial direction of the speaker device 1 is the horizontal direction of the paper surface, the near side, and the depth direction. In FIG. 1, the sound emission direction of the speaker device 1 is assumed to be upward. The same applies to FIG.
The speaker device 1 includes at least a diaphragm 10, a voice coil 20, a frame 30, and a magnetic circuit 100.
　振動板１０は、軸方向に機械的に振動して音を放射する。振動板１０の振動は、ボイスコイル２０の軸方向の往復運動に連動する。
　振動板１０は、金属材料、樹脂材料、繊維材料、又はこれらの混合材料等を用いて、略円板形状に形成されている。略円板形状の中心軸は、スピーカー装置１の軸方向と略同一である。
　図１の振動板１０は、振動部１１と、ダンパ部１２と、エッジ部１３とを有する。振動部１１、ダンパ部１２、及びエッジ部１３は、一体成形されている。 The diaphragm 10 radiates sound by mechanically vibrating in the axial direction. The vibration of the diaphragm 10 is interlocked with the reciprocating motion of the voice coil 20 in the axial direction.
The diaphragm 10 is formed in a substantially disc shape using a metal material, a resin material, a fiber material, or a mixed material thereof. The central axis of the substantially disc shape is substantially the same as the axial direction of the speaker device 1.
The diaphragm 10 in FIG. 1 includes a vibration part 11, a damper part 12, and an edge part 13. The vibration part 11, the damper part 12, and the edge part 13 are integrally formed.
　振動部１１は、振動板１０の本体部分であり、軸方向に振動自在である。振動板１０は、振動部１１の振動によって発生した音波を上方に放射する。
　振動部１１は、上方に凸のドーム形状を有し、振動板１０の中央に形成されている。図１の振動部１１は、断面視が略半円形状であるが、略放物線形状、略円錐形状、略多段曲線形状等でもよい。
　振動部１１の外周の背面側（音放射方向とは反対側）には、振動板１０の振動を駆動するボイスコイル２０が巻回されたボイスコイルボビン２１が、軸方向で振動自在に接続されている。 The vibration part 11 is a main body part of the diaphragm 10 and can vibrate in the axial direction. The diaphragm 10 radiates a sound wave generated by the vibration of the vibration unit 11 upward.
The vibration part 11 has a dome shape convex upward, and is formed at the center of the vibration plate 10. The vibration unit 11 in FIG. 1 has a substantially semicircular cross-sectional view, but may have a substantially parabolic shape, a substantially conical shape, a substantially multi-stage curve shape, or the like.
A voice coil bobbin 21 around which a voice coil 20 that drives the vibration of the diaphragm 10 is wound is connected to the back side of the outer periphery of the vibration unit 11 (opposite to the sound radiation direction) so as to vibrate in the axial direction. Yes.
　ダンパ部１２は、振動板１０の径方向の振動を規制すると共に、軸方向の振動中心を保持する。
　ダンパ部１２は、断面視が上方に凸の略円弧形状を有し、振動部１１の外周に形成されている。 The damper portion 12 regulates the radial vibration of the diaphragm 10 and holds the axial vibration center.
The damper portion 12 has a substantially arc shape that is convex upward in cross-sectional view, and is formed on the outer periphery of the vibration portion 11.
　エッジ部１３は、振動板１０をフレーム３０へ掛け渡す。エッジ部１３は、ダンパ部１２と共に振動板１０の振動を規制・制御する。エッジ部１３は、振動板１０の背面側（音放射方向とは反対側）の音を遮断する。
　エッジ部１３は、断面視が径方向に延出する略直線形状を有し、ダンパ部１２の外周に形成され、フレーム３０に固定されている。 The edge portion 13 spans the diaphragm 10 to the frame 30. The edge portion 13 regulates and controls the vibration of the diaphragm 10 together with the damper portion 12. The edge portion 13 blocks sound on the back side of the diaphragm 10 (on the side opposite to the sound emission direction).
The edge portion 13 has a substantially linear shape with a cross-sectional view extending in the radial direction, is formed on the outer periphery of the damper portion 12, and is fixed to the frame 30.
　ボイスコイル２０は、振動板１０の振動の駆動源である。
　ボイスコイル２０は、中心軸が軸方向の略円筒形状を有するボイスコイルボビン２１の外周に巻回されている。ボイスコイル２０の中心軸は、軸方向であり、ボイスコイルボビン２１の中心軸と略同一である。ボイスコイル２０が巻回される場所は、ボイスコイルボビン２１の下方側（音放射方向とは反対方向側）の端部である。ボイスコイル２０の巻回方向は、略円筒形状に形成されたボイスコイルボビン２１の中心軸が延出する方向（軸方向）と略直交する。ボイスコイル２０の巻幅の幅方向（巻幅の増加方向）は、ボイスコイルボビン２１の中心軸が延出する方向（軸方向）と略平行である。
　ボイスコイルボビン２１の上方側（音放射方向側）の端部には、振動板１０が接続されている。 The voice coil 20 is a driving source for vibration of the diaphragm 10.
The voice coil 20 is wound around the outer periphery of a voice coil bobbin 21 whose central axis has a substantially cylindrical shape in the axial direction. The central axis of the voice coil 20 is the axial direction and is substantially the same as the central axis of the voice coil bobbin 21. The place where the voice coil 20 is wound is the end of the voice coil bobbin 21 on the lower side (the direction opposite to the sound radiation direction). The winding direction of the voice coil 20 is substantially orthogonal to the direction (axial direction) in which the central axis of the voice coil bobbin 21 formed in a substantially cylindrical shape extends. The width direction of the winding width of the voice coil 20 (increase direction of the winding width) is substantially parallel to the direction (axial direction) in which the central axis of the voice coil bobbin 21 extends.
The diaphragm 10 is connected to the upper end (sound radiation direction side) of the voice coil bobbin 21.
　ボイスコイル２０は、磁気回路１００の磁気ギャップＧ内に配置される。磁気ギャップＧは、磁気回路１００の後述するプレート１１０とヨーク１２０との間に形成されている。磁気ギャップＧ内に配置されたボイスコイル２０は、プレート１１０と次のような位置関係にある。具体的には、ボイスコイル２０の巻幅の軸方向での中央位置と、プレート１１０の軸方向の厚さの中央位置とが、略同一の位置関係にある（図１の要部拡大図を参照）。軸方向は、後述するように磁石１３０の磁化方向と略平行である。すなわち、ボイスコイル２０は、その巻幅の磁化方向での中央位置が、プレート１１０の磁化方向での厚さの中央位置と略同一となるように配置されている。 The voice coil 20 is disposed in the magnetic gap G of the magnetic circuit 100. The magnetic gap G is formed between a plate 110 (described later) of the magnetic circuit 100 and a yoke 120. The voice coil 20 arranged in the magnetic gap G has the following positional relationship with the plate 110. Specifically, the central position in the axial direction of the winding width of the voice coil 20 and the central position of the thickness in the axial direction of the plate 110 have substantially the same positional relationship (see an enlarged view of the main part in FIG. 1). reference). The axial direction is substantially parallel to the magnetization direction of the magnet 130 as will be described later. That is, the voice coil 20 is arranged so that the center position of the winding width in the magnetization direction is substantially the same as the center position of the thickness in the magnetization direction of the plate 110.
　ボイスコイル２０には、図示しないスピーカーアンプとリード線を介して接続されている。ボイスコイル２０には、当該スピーカーアンプから音声電流が供給される。ボイスコイル２０は、音声電流が供給されると、磁気ギャップＧの磁束と当該電流との相互作用によって電磁力を受ける。電磁力を受けたボイスコイル２０は、当該電磁力を駆動力として、磁気ギャップＧ内で軸方向に往復運動する。軸方向に往復運動するボイスコイル２０は、ボイスコイルボビン２１に接続された振動板１０を軸方向に振動させる。
　このようにして、ボイスコイル２０は、供給された音声電流を機械的振動に変換して、振動板１０に軸方向の駆動力を与える。 The voice coil 20 is connected to a speaker amplifier (not shown) via a lead wire. A voice current is supplied to the voice coil 20 from the speaker amplifier. When an audio current is supplied, the voice coil 20 receives an electromagnetic force due to the interaction between the magnetic flux of the magnetic gap G and the current. The voice coil 20 receiving the electromagnetic force reciprocates in the axial direction within the magnetic gap G using the electromagnetic force as a driving force. The voice coil 20 that reciprocates in the axial direction vibrates the diaphragm 10 connected to the voice coil bobbin 21 in the axial direction.
In this way, the voice coil 20 converts the supplied audio current into mechanical vibration and gives the diaphragm 10 an axial driving force.
　フレーム３０は、スピーカー装置１の骨格であり、振動板１０及び磁気回路１００を支持する。
　フレーム３０は、金属材料を用いて、中心軸が軸方向の略円環形状に形成されている。フレーム３０は、その下方部を基端とし先端が径方向内側へ屈曲して延出した屈曲部３１を有する。屈曲部３１の上面側には、平坦部３２を有する。平坦部３２には、振動板１０のエッジ部１３が固定されている。屈曲部３１の先端には、磁気回路１００の後述するヨーク１２０が固定されている。 The frame 30 is a skeleton of the speaker device 1 and supports the diaphragm 10 and the magnetic circuit 100.
The frame 30 is formed of a metal material in a substantially annular shape with a central axis in the axial direction. The frame 30 has a bent portion 31 having a lower portion as a base end and a distal end bent and extended radially inward. A flat portion 32 is provided on the upper surface side of the bent portion 31. The edge portion 13 of the diaphragm 10 is fixed to the flat portion 32. A yoke 120 described later of the magnetic circuit 100 is fixed to the tip of the bent portion 31.
　図２は、本発明の一実施形態に係る磁気回路１００の概略図である。
　磁気回路１００は、ボイスコイル２０を収容可能な磁気ギャップＧを形成し、ボイスコイル２０の振動に必要な磁束を供給する。
　磁気回路１００は、いわゆる内磁型のスピーカー装置用磁気回路である。
　磁気回路１００は、プレート１１０と、ヨーク１２０と、磁石１３０とを有する。磁気回路１００は、ヨーク１２０、磁石１３０、及びプレート１１０を、下方から上方に向かって順に積層させた構造を有する。
　図２では、磁石１３０の磁化方向の厚さをＬｍ、プレート１１０の磁化方向での厚さをＬｐと表記している。 FIG. 2 is a schematic diagram of a magnetic circuit 100 according to an embodiment of the present invention.
The magnetic circuit 100 forms a magnetic gap G that can accommodate the voice coil 20, and supplies magnetic flux necessary for vibration of the voice coil 20.
The magnetic circuit 100 is a so-called inner magnet type magnetic circuit for a speaker device.
The magnetic circuit 100 includes a plate 110, a yoke 120, and a magnet 130. The magnetic circuit 100 has a structure in which a yoke 120, a magnet 130, and a plate 110 are stacked in order from the bottom to the top.
In FIG. 2, the thickness of the magnet 130 in the magnetization direction is expressed as Lm, and the thickness of the plate 110 in the magnetization direction is expressed as Lp.
　プレート１１０は、磁気回路１００の磁路及び磁気ギャップＧの一端を形成する。
　プレート１１０は、鉄等の磁性材料を用いて、中心軸が軸方向の略円柱形状に形成されている。略円柱形状のプレート１１０の中心軸は、ボイスコイル２０及びボイスコイルボビン２１の中心軸と略同一である。すなわち、プレート１１０は、ボイスコイル２０及びボイスコイルボビン２１と略同心円にある。
　プレート１１０の外径は、ボイスコイル２０及びボイスコイルボビン２１の内径より小さい。プレート１１０の厚さＬｐは、略均一である。 The plate 110 forms one end of the magnetic path of the magnetic circuit 100 and the magnetic gap G.
The plate 110 is made of a magnetic material such as iron and has a substantially cylindrical shape with a central axis in the axial direction. The central axis of the substantially cylindrical plate 110 is substantially the same as the central axis of the voice coil 20 and the voice coil bobbin 21. That is, the plate 110 is substantially concentric with the voice coil 20 and the voice coil bobbin 21.
The outer diameter of the plate 110 is smaller than the inner diameter of the voice coil 20 and the voice coil bobbin 21. The thickness Lp of the plate 110 is substantially uniform.
　プレート１１０の下方側の底面（下面）は、磁石１３０の一極側（例えば、Ｓ極側）と磁気的に接合している。プレート１１０内には、磁石１３０が供給する磁束が通過する。
　プレート１１０の外周面１１１は、ボイスコイル２０及びボイスコイルボビン２１の中心軸と略平行である。プレート１１０の外周面１１１は、後述するヨーク１２０の内周面１２３と対向しており、磁気ギャップＧの一端を形成する。 The bottom surface (lower surface) on the lower side of the plate 110 is magnetically bonded to one pole side (for example, the S pole side) of the magnet 130. The magnetic flux supplied from the magnet 130 passes through the plate 110.
The outer peripheral surface 111 of the plate 110 is substantially parallel to the central axis of the voice coil 20 and the voice coil bobbin 21. An outer peripheral surface 111 of the plate 110 faces an inner peripheral surface 123 of a yoke 120 described later, and forms one end of the magnetic gap G.
　ヨーク１２０は、磁気回路１００の磁路及び磁気ギャップＧの一端を形成する。
　ヨーク１２０は、中心軸が軸方向の略円板形状の底部１２１と、底部１２１の外周を基端として先端が軸方向と略平行に上方へ延出する略円筒形状の側部１２２とを有する。略円板形状の底部１２１及び略円筒形状の側部１２２の中心軸は、ボイスコイル２０及びボイスコイルボビン２１の中心軸と略同一である。
　底部１２１及び側部１２２は、鉄等の磁性材料を用いて形成されており、一体成形されている。底部１２１の外径及び側部１２２の内径は、ボイスコイル２０及びボイスコイルボビン２１の外径より大きい。底部１２１及び側部１２２の厚さは、略均一である。 The yoke 120 forms one end of the magnetic path of the magnetic circuit 100 and the magnetic gap G.
The yoke 120 has a substantially disc-shaped bottom 121 having a central axis in the axial direction, and a substantially cylindrical side 122 having a distal end extending substantially parallel to the axial direction with the outer periphery of the bottom 121 as a base end. . The central axes of the substantially disc-shaped bottom portion 121 and the substantially cylindrical side portion 122 are substantially the same as the central axes of the voice coil 20 and the voice coil bobbin 21.
The bottom part 121 and the side part 122 are formed using magnetic materials, such as iron, and are integrally molded. The outer diameter of the bottom part 121 and the inner diameter of the side part 122 are larger than the outer diameters of the voice coil 20 and the voice coil bobbin 21. The thickness of the bottom part 121 and the side part 122 is substantially uniform.
　底部１２１の上面は、磁石１３０の他極側（プレート１１０と接合する磁極とは異なる側であり、例えば、Ｎ極側）と磁気的に接合している。ヨーク１２０内には、磁石１３０が供給する磁束が通過する。
　側部１２２の延出先端の端面は、プレート１１０の上方側の底面（上面）と略同一の高さにある。すなわち、側部１２２の延出先端の端面は、プレート１１０の磁石１３０とは反対側に位置する底面と、略同一平面上にある。言い換えると、側部１２２の延出先端における延出長さは、磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの和に、略等しい。
　側部１２２の先端の内周面１２３は、ボイスコイル２０及びボイスコイルボビン２１の中心軸と略平行である。側部１２２の先端の内周面１２３は、プレート１１０の外周面１１１と略平行に対向しており、磁気ギャップＧの一端を形成する。 The upper surface of the bottom 121 is magnetically joined to the other pole side of the magnet 130 (the side different from the magnetic pole joined to the plate 110, for example, the N pole side). The magnetic flux supplied from the magnet 130 passes through the yoke 120.
The end surface of the extending tip of the side portion 122 is substantially at the same height as the upper bottom surface (upper surface) of the plate 110. That is, the end surface of the extending tip of the side portion 122 is substantially on the same plane as the bottom surface of the plate 110 located on the side opposite to the magnet 130. In other words, the extension length at the extension tip of the side portion 122 is substantially equal to the sum of the thickness Lm of the magnet 130 and the thickness Lp of the plate 110.
The inner peripheral surface 123 at the tip of the side portion 122 is substantially parallel to the central axis of the voice coil 20 and the voice coil bobbin 21. An inner peripheral surface 123 at the tip of the side portion 122 faces the outer peripheral surface 111 of the plate 110 substantially in parallel, and forms one end of the magnetic gap G.
　磁気ギャップＧは、互いに略平行に対向するプレート１１０の外周面１１１とヨーク１２０の内周面１２３との間に形成され、中心軸が軸方向の略円筒形状を有する。略円筒形状の磁気ギャップＧの内径は、プレート１１０の外径に相当する。略円筒形状の磁気ギャップＧの外径はヨーク１２０の内径に相当する。磁気回路１００は、この磁気ギャップＧ内に、ボイスコイルボビン２１に巻回されたボイスコイル２０を配置する。 The magnetic gap G is formed between the outer peripheral surface 111 of the plate 110 and the inner peripheral surface 123 of the yoke 120 facing each other substantially parallel to each other, and has a substantially cylindrical shape whose central axis is the axial direction. The inner diameter of the substantially cylindrical magnetic gap G corresponds to the outer diameter of the plate 110. The outer diameter of the substantially cylindrical magnetic gap G corresponds to the inner diameter of the yoke 120. In the magnetic circuit 100, the voice coil 20 wound around the voice coil bobbin 21 is disposed in the magnetic gap G.
　磁石１３０は、磁気回路１００内、特に、磁気ギャップＧに磁束を供給する。
　磁石１３０は、中心軸が軸方向の略円柱形状に形成されている。略円柱形状の磁石１３０の中心軸は、ボイスコイル２０、ボイスコイルボビン２１、プレート１１０、及びヨーク１２０（底部１２１及び側部１２２）の中心軸と略同一である。すなわち、磁石１３０は、ボイスコイル２０、ボイスコイルボビン２１、プレート１１０、ヨーク１２０（底部１２１及び側部１２２）と、略同心円にある。
　磁石１３０の外径は、プレート１１０の外径と同程度か小さい。磁石１３０の側面は、磁気ギャップＧ内に配置されたボイスコイル２０と接触しない。磁石１３０の厚さＬｍは、略均一である。 The magnet 130 supplies magnetic flux to the magnetic circuit 100, particularly to the magnetic gap G.
The magnet 130 is formed in a substantially cylindrical shape whose central axis is the axial direction. The central axis of the substantially cylindrical magnet 130 is substantially the same as the central axes of the voice coil 20, the voice coil bobbin 21, the plate 110, and the yoke 120 (the bottom 121 and the side 122). That is, the magnet 130 is substantially concentric with the voice coil 20, the voice coil bobbin 21, the plate 110, and the yoke 120 (the bottom portion 121 and the side portion 122).
The outer diameter of the magnet 130 is the same as or smaller than the outer diameter of the plate 110. The side surface of the magnet 130 does not contact the voice coil 20 disposed in the magnetic gap G. The thickness Lm of the magnet 130 is substantially uniform.
　磁石１３０の上方側の底面（上面）及び下方側の底面（下面）は、互いに異なる磁極を有し、一対の磁極を形成している。磁石１３０の磁化方向は、磁石１３０の各底面の一方側から他方側へ向かう方向（上面から下面、又は下面から上面へ向かう方向）であり、軸方向に略平行である。すなわち、磁石１３０の磁化方向は、磁石１３０の厚さ方向、プレート１１０の厚さ方向、ヨーク１２０の側部１２２が延出する方向、及びボイスコイルボビン２１の中心軸が延出する方向、及びボイスコイル２０の巻幅の幅方向等と、略平行である。
　一方の磁極（例えば、Ｓ極）を有する磁石１３０の上方側の底面（上面）は、プレート１１０の下方側の底面（下面）と磁気的に接合している。他方の磁極（例えば、Ｎ極）を有する磁石１３０の下方側の底面（下面）は、ヨーク１２０を構成する底部１２１の上面と磁気的に接合している。 The upper bottom surface (upper surface) and the lower bottom surface (lower surface) of the magnet 130 have different magnetic poles to form a pair of magnetic poles. The magnetization direction of the magnet 130 is a direction from one side to the other side of each bottom surface of the magnet 130 (a direction from the upper surface to the lower surface or from the lower surface to the upper surface), and is substantially parallel to the axial direction. That is, the magnetization direction of the magnet 130 is the thickness direction of the magnet 130, the thickness direction of the plate 110, the direction in which the side portion 122 of the yoke 120 extends, the direction in which the central axis of the voice coil bobbin 21 extends, and the voice It is substantially parallel to the width direction of the winding width of the coil 20 and the like.
The upper bottom surface (upper surface) of the magnet 130 having one magnetic pole (for example, the S pole) is magnetically joined to the lower bottom surface (lower surface) of the plate 110. The bottom surface (lower surface) on the lower side of the magnet 130 having the other magnetic pole (for example, N pole) is magnetically joined to the upper surface of the bottom 121 constituting the yoke 120.
　本実施形態では、磁気回路１００は、磁気ギャップＧを形成する外周面１１１と、内周面１２３とを、略平行に対向して設けている。そして、外周面１１１及び内周面１２３は、ボイスコイル２０に供給される音声電流の方向及びボイスコイル２０の往復運動可能な方向と略平行である。よって、磁気ギャップＧに供給される磁束の方向は、ボイスコイル２０に供給される音声電流の方向及びボイスコイル２０の往復運動可能な方向と略直交する。このため、磁気回路１００では、磁気ギャップＧ内の磁束及び音声電流の相互作用によって発生する電磁力を、効率的にボイスコイル２０へ与えることができる。 In the present embodiment, the magnetic circuit 100 is provided with the outer peripheral surface 111 forming the magnetic gap G and the inner peripheral surface 123 facing each other substantially in parallel. The outer peripheral surface 111 and the inner peripheral surface 123 are substantially parallel to the direction of the audio current supplied to the voice coil 20 and the direction in which the voice coil 20 can reciprocate. Therefore, the direction of the magnetic flux supplied to the magnetic gap G is substantially orthogonal to the direction of the audio current supplied to the voice coil 20 and the direction in which the voice coil 20 can reciprocate. For this reason, in the magnetic circuit 100, the electromagnetic force generated by the interaction between the magnetic flux in the magnetic gap G and the sound current can be efficiently applied to the voice coil 20.
　また、磁気回路１００は、いわゆる内磁型のスピーカー装置用磁気回路である。内磁型のスピーカー装置用磁気回路は、磁石を磁気ギャップよりも径方向内側に配置した回路である。一方、外磁型のスピーカー装置用磁気回路は、磁石を磁気ギャップよりも径方向外側に配置した磁気回路である。 Further, the magnetic circuit 100 is a so-called inner-magnet type speaker device magnetic circuit. The magnetic circuit for the speaker device of the internal magnet type is a circuit in which the magnet is arranged radially inward from the magnetic gap. On the other hand, the magnetic circuit for the speaker device of the outer magnet type is a magnetic circuit in which the magnet is arranged radially outside the magnetic gap.
　スピーカー装置では、所望の音域特性を達成するためにボイスコイルの設計仕様が予め決まっていることが多い。よって、磁気ギャップの内径及び外径寸法は、予め制約されることが多い。この場合、内磁型のスピーカー装置用磁気回路は、磁気ギャップよりも径方向内側に磁石を配置するため、外磁型よりも磁石の直径を小さくすることができる。 In speaker devices, the design specifications of the voice coil are often predetermined in order to achieve the desired sound range characteristics. Therefore, the inner and outer diameter dimensions of the magnetic gap are often restricted in advance. In this case, since the magnet circuit for the inner-magnet type speaker device has the magnet arranged radially inside the magnetic gap, the diameter of the magnet can be made smaller than that of the outer-magnet type.
　よって、内磁型のスピーカー装置用磁気回路である磁気回路１００では、磁石１３０を小径化することができる。このため、磁気回路１００では、プレート１１０及びヨーク１２０を含む磁気回路全体を小型化することができる。ゆえに、磁気回路１００では、磁気回路の軽量化及び低コスト化が可能である。磁気回路１００を有するスピーカー装置１も、小型化、軽量化、及び低コスト化が可能である。 Therefore, in the magnetic circuit 100 which is an internal magnet type speaker circuit magnetic circuit, the diameter of the magnet 130 can be reduced. For this reason, in the magnetic circuit 100, the whole magnetic circuit including the plate 110 and the yoke 120 can be reduced in size. Therefore, the magnetic circuit 100 can reduce the weight and cost of the magnetic circuit. The speaker device 1 having the magnetic circuit 100 can also be reduced in size, weight, and cost.
　上記構造の磁気回路１００では、磁気回路１００の主要部材である磁石１３０に、Ｆｅ－Ｃｒ－Ｃｏ（鉄－クロム－コバルト）系磁石を用いている。Ｆｅ－Ｃｒ－Ｃｏ系磁石は、逆温度特性がフェライト系磁石よりも優れており、温度上昇による減磁量が小さい。 In the magnetic circuit 100 having the above structure, an Fe—Cr—Co (iron-chromium-cobalt) -based magnet is used as the magnet 130 which is a main member of the magnetic circuit 100. Fe-Cr-Co magnets have better reverse temperature characteristics than ferrite magnets, and the amount of demagnetization due to temperature rise is small.
　図３は、本発明の一実施形態に係る磁気回路１００が有する磁石１３０の磁気特性を説明するための図である。
　図３の縦軸は、磁石の磁束密度Ｂであり、図３の横軸は、磁界の強さＨである。
　図３の曲線は、磁石１３０の構成材料であるＦｅ－Ｃｒ－Ｃｏ系磁石の減磁曲線である。減磁曲線の縦軸との切片は、残留磁束密度Ｂｒを示し、減磁曲線の横軸との切片は、保磁力Ｈｃｂを示している。減磁曲線は、磁化曲線（Ｂ－Ｈ曲線）の第二象限であり、磁石の磁気特性を示している。 FIG. 3 is a diagram for explaining the magnetic characteristics of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
The vertical axis in FIG. 3 is the magnetic flux density B of the magnet, and the horizontal axis in FIG. 3 is the magnetic field strength H.
The curve in FIG. 3 is a demagnetization curve of an Fe—Cr—Co based magnet that is a constituent material of the magnet 130. The intercept with the vertical axis of the demagnetization curve indicates the residual magnetic flux density Br, and the intercept with the horizontal axis of the demagnetization curve indicates the coercive force Hcb. The demagnetization curve is the second quadrant of the magnetization curve (BH curve) and indicates the magnetic characteristics of the magnet.
　磁気ギャップＧの磁束密度Ｂｇは、磁気回路１００が有する磁石１３０の動作点ｄの磁束密度Ｂｄに依存する。磁気ギャップＧの磁束密度Ｂｇを高めるためには、磁石１３０の動作点ｄの磁束密度Ｂｄを高める必要がある。 The magnetic flux density Bg of the magnetic gap G depends on the magnetic flux density Bd at the operating point d of the magnet 130 included in the magnetic circuit 100. In order to increase the magnetic flux density Bg of the magnetic gap G, it is necessary to increase the magnetic flux density Bd at the operating point d of the magnet 130.
　磁石１３０の動作点ｄは、磁石１３０のパーミアンス係数Ｐｃと、減磁曲線とによって求めることができる。パーミアンス係数Ｐｃは、磁石から外部に向かっての磁束の供給し易さを示し、磁石１３０及び磁気ギャップＧの形状に依存する。 The operating point d of the magnet 130 can be obtained from the permeance coefficient Pc of the magnet 130 and the demagnetization curve. The permeance coefficient Pc indicates the ease of supplying the magnetic flux from the magnet to the outside, and depends on the shape of the magnet 130 and the magnetic gap G.
　磁石１３０の動作点ｄは、パーミアンス直線（パーミアンス係数Ｐｃと真空透磁率μ０との積を傾きとし、減磁曲線の原点を通る直線）と、減磁曲線との交点に相当する。
　パーミアンス係数Ｐｃが高くなると、パーミアンス直線の傾きが大きくなる。パーミアンス直線の傾きが大きくなると、動作点ｄの位置は、減磁曲線上の残留磁束密度Ｂｒに近付く。動作点ｄの磁束密度Ｂｄの取り得る値は、最大でも、減磁曲線の残留磁束密度Ｂｒとなる。 The operating point d of the magnet 130 corresponds to the intersection of a permeance straight line (a straight line passing through the origin of the demagnetization curve with the product of the permeance coefficient Pc and the vacuum permeability μ 0 as an inclination) and the demagnetization curve.
As the permeance coefficient Pc increases, the slope of the permeance straight line increases. When the inclination of the permeance line increases, the position of the operating point d approaches the residual magnetic flux density Br on the demagnetization curve. The maximum value of the magnetic flux density Bd at the operating point d is the residual magnetic flux density Br of the demagnetization curve.
　動作点ｄの磁束密度Ｂｄを高めるためには、磁石１３０の構成材料を、残留磁束密度Ｂｒが大きな減磁曲線を有する材料とする必要がある。また、動作点ｄの磁束密度Ｂｄを高めるためには、磁石１３０及び磁気ギャップＧの形状を、パーミアンス係数Ｐｃが高い形状とする必要がある。 In order to increase the magnetic flux density Bd at the operating point d, the constituent material of the magnet 130 needs to be a material having a demagnetization curve with a large residual magnetic flux density Br. Further, in order to increase the magnetic flux density Bd at the operating point d, the shape of the magnet 130 and the magnetic gap G needs to be a shape having a high permeance coefficient Pc.
　磁石１３０の構成材料であるＦｅ－Ｃｒ－Ｃｏ系磁石は、その残留磁束密度Ｂｒが、フェライト系磁石の残留磁束密度Ｂｒよりも著しく大きい。よって、磁石１３０及び磁気ギャップＧの形状を、パーミアンス係数Ｐｃが高い形状とすれば、動作点ｄの磁束密度Ｂｄを高めることができる。動作点ｄの磁束密度Ｂｄを高めることができれば、磁気ギャップＧでの磁束密度Ｂｇを高めることができる。 The residual magnetic flux density Br of the Fe—Cr—Co based magnet that is a constituent material of the magnet 130 is significantly larger than the residual magnetic flux density Br of the ferrite based magnet. Therefore, if the shape of the magnet 130 and the magnetic gap G is a shape having a high permeance coefficient Pc, the magnetic flux density Bd at the operating point d can be increased. If the magnetic flux density Bd at the operating point d can be increased, the magnetic flux density Bg at the magnetic gap G can be increased.
　Ｆｅ－Ｃｒ－Ｃｏ系磁石の減磁曲線は、図３に示すように、磁束密度Ｂと磁界の強さＨとの関係が線形ではなく、屈曲点Ｋを有する。屈曲点Ｋは、減磁曲線の勾配が大きく変化する点である。 In the demagnetization curve of the Fe—Cr—Co magnet, the relationship between the magnetic flux density B and the magnetic field strength H is not linear and has a bending point K as shown in FIG. The bending point K is a point where the gradient of the demagnetization curve changes greatly.
　Ｆｅ－Ｃｒ－Ｃｏ系磁石の減磁曲線の勾配は、屈曲点Ｋよりも保磁力Ｈｃｂ側（例えば、図３のＰｃ＝Ｐｃ１との交点ｄ１）では、急峻である。勾配が急峻であるのは、磁石１３０内の反磁界Ｈｄによって磁石１３０の磁化Ｍを低下させる作用が大きいことに起因する。 The gradient of the demagnetization curve of the Fe—Cr—Co magnet is steep on the coercive force Hcb side of the bending point K (for example, the intersection d1 with Pc = Pc1 in FIG. 3). The steep gradient is due to the great effect of reducing the magnetization M of the magnet 130 by the demagnetizing field Hd in the magnet 130.
　Ｆｅ－Ｃｒ－Ｃｏ系磁石の減磁曲線の勾配は、屈曲点Ｋよりも残留磁束密度Ｂｒ側（例えば、図３のＰｃ＝Ｐｃ２との交点ｄ２）では、緩やかである。勾配が緩やかであるのは、磁石１３０内の反磁界Ｈｄによって磁石１３０の磁化Ｍを低下させる作用が小さいことに起因する。 The gradient of the demagnetization curve of the Fe—Cr—Co magnet is gentler on the side of the residual magnetic flux density Br than the bending point K (for example, the intersection d2 with Pc = Pc2 in FIG. 3). The reason why the gradient is gentle is that the action of lowering the magnetization M of the magnet 130 by the demagnetizing field Hd in the magnet 130 is small.
　動作点ｄが屈曲点Ｋより残留磁束密度Ｂｒ側に位置する場合、反磁界Ｈｄによって磁化Ｍを低下させる作用は小さいため、磁束密度Ｂｄを高めることができる。
　反磁界Ｈｄの強さは、磁石１３０及び磁気ギャップＧの形状に依存する。反磁界Ｈｄが小さい磁石１３０及び磁気ギャップの形状は、パーミアンス係数Ｐｃが高い形状である。
　よって、磁石１３０及び磁気ギャップＧの形状は、動作点ｄが屈曲点Ｋより残留磁束密度Ｂｒ側に位置する程度に、高いパーミアンス係数Ｐｃを有する形状であることが好ましい。 When the operating point d is located on the side of the residual magnetic flux density Br with respect to the bending point K, the action of reducing the magnetization M by the demagnetizing field Hd is small, so that the magnetic flux density Bd can be increased.
The strength of the demagnetizing field Hd depends on the shape of the magnet 130 and the magnetic gap G. The shape of the magnet 130 and the magnetic gap with a small demagnetizing field Hd is a shape with a high permeance coefficient Pc.
Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a high permeance coefficient Pc so that the operating point d is positioned on the residual magnetic flux density Br side from the bending point K.
　また、磁石１３０は、ボイスコイル２０の駆動により発生する交流磁界等の外部磁界の影響を受ける。磁石１３０は、外部磁界の影響を受けると、動作点ｄが変動する。磁石１３０の動作点ｄが、屈曲点Ｋより残留磁束密度Ｂｒ側に位置する場合は、動作点ｄが変動しても磁束密度Ｂｄが変動し難い。磁束密度Ｂｄが変動し難いと、磁気ギャップＧの磁束密度Ｂｇが安定する。
　よって、磁石１３０及び磁気ギャップＧの形状は、動作点ｄが屈曲点Ｋより残留磁束密度Ｂｒ側に位置する程度に、高いパーミアンス係数Ｐｃを有する形状であることが好ましい。 Further, the magnet 130 is affected by an external magnetic field such as an alternating magnetic field generated by driving the voice coil 20. When the magnet 130 is affected by an external magnetic field, the operating point d fluctuates. When the operating point d of the magnet 130 is located on the side of the residual magnetic flux density Br from the bending point K, the magnetic flux density Bd hardly changes even if the operating point d varies. If the magnetic flux density Bd hardly changes, the magnetic flux density Bg of the magnetic gap G is stabilized.
Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a high permeance coefficient Pc so that the operating point d is positioned on the residual magnetic flux density Br side from the bending point K.
　また、磁石１３０の動作点ｄのエネルギー積（Ｂｄ×Ｈｄ）は、磁石１３０が外部へ供給可能な単位体積当たりの磁気エネルギーに比例する。エネルギー積が大きいほど、所望の磁気エネルギーを得るために必要な磁石体積を小さくすることができる。動作点ｄのエネルギー積が大きい方が、磁石１３０の使用効率がよい。図３に示すように、磁石１３０の最大エネルギー積（ＢＨｍａｘ）は、屈曲点Ｋ近傍でのエネルギー積である。
　よって、磁石１３０及び磁気ギャップＧの形状は、動作点ｄが屈曲点Ｋ近傍に位置するようなパーミアンス係数Ｐｃを有する形状であることが好ましい。 The energy product (Bd × Hd) at the operating point d of the magnet 130 is proportional to the magnetic energy per unit volume that the magnet 130 can supply to the outside. The larger the energy product, the smaller the magnet volume required to obtain the desired magnetic energy. The use efficiency of the magnet 130 is better when the energy product of the operating point d is larger. As shown in FIG. 3, the maximum energy product (BHmax) of the magnet 130 is an energy product near the bending point K.
Therefore, the shape of the magnet 130 and the magnetic gap G is preferably a shape having a permeance coefficient Pc such that the operating point d is positioned in the vicinity of the bending point K.
　このように、上記磁気特性の磁石１３０を有する磁気回路１００において、磁石の使用効率と磁束密度Ｂｇとの両立を図るためには、磁石１３０及び磁気ギャップＧの形状を、次のように設計すればよい。すなわち、磁石１３０及び磁気ギャップＧの形状を、動作点ｄが屈曲点Ｋより残留磁束密度Ｂｒ側で、且つ、屈曲点Ｋ近傍に位置するようなパーミアンス係数Ｐｃの形状であるように設計すればよい。 As described above, in the magnetic circuit 100 having the magnet 130 having the above magnetic characteristics, in order to achieve both the use efficiency of the magnet and the magnetic flux density Bg, the shapes of the magnet 130 and the magnetic gap G are designed as follows. That's fine. That is, if the shapes of the magnet 130 and the magnetic gap G are designed so that the operating point d is located on the side of the residual magnetic flux density Br from the bending point K and in the vicinity of the bending point K, the permeance coefficient Pc. Good.
　なお、パーミアンス係数Ｐｃは、磁石１３０の磁化方向の厚さＬｍ及び磁気ギャップＧの断面積を大きくすると、高くなる。しかし、磁気ギャップＧの断面積を大きくすると、磁気ギャップＧの磁束密度Ｂｇは低下する。磁気ギャップＧの断面積は、プレート１１０の厚さＬｐとプレート１１０の直径に依存する。プレート１１０の直径は、ボイスコイル２０の設計仕様によって予め制約されることが多い。このため、設計自由度の高いプレート１１０の厚さＬｐに着目する。 In addition, the permeance coefficient Pc increases as the thickness Lm in the magnetization direction of the magnet 130 and the cross-sectional area of the magnetic gap G are increased. However, when the cross-sectional area of the magnetic gap G is increased, the magnetic flux density Bg of the magnetic gap G decreases. The cross-sectional area of the magnetic gap G depends on the thickness Lp of the plate 110 and the diameter of the plate 110. The diameter of the plate 110 is often constrained in advance by the design specifications of the voice coil 20. For this reason, attention is paid to the thickness Lp of the plate 110 having a high degree of design freedom.
　すなわち、上記磁気特性の磁石１３０を有する磁気回路１００において、磁石の使用効率と磁束密度Ｂｇとの両立を図るためには、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐを最適化すればよい。 That is, in the magnetic circuit 100 having the magnet 130 having the above magnetic characteristics, in order to achieve both the use efficiency of the magnet and the magnetic flux density Bg, the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 should be optimized. Good.
　図４は、本発明の一実施形態に係る磁気回路１００が有する磁気ギャップＧの磁束密度Ｂｇを示すグラフである。
　図４の縦軸は、磁気ギャップＧの磁束密度Ｂｇであり、図４の横軸は、磁石１３０の厚さＬｍである。
　図４の曲線は、プレート１１０の厚さＬｐ毎に磁石１３０の厚さＬｍを変化させたときの、磁石１３０の厚さＬｍと磁束密度Ｂｇとの関係を示している。 FIG. 4 is a graph showing the magnetic flux density Bg of the magnetic gap G included in the magnetic circuit 100 according to the embodiment of the present invention.
The vertical axis in FIG. 4 is the magnetic flux density Bg of the magnetic gap G, and the horizontal axis in FIG. 4 is the thickness Lm of the magnet 130.
The curve in FIG. 4 shows the relationship between the thickness Lm of the magnet 130 and the magnetic flux density Bg when the thickness Lm of the magnet 130 is changed for each thickness Lp of the plate 110.
　図４に示すように、磁石１３０の厚さＬｍが７ｍｍより小さいと、磁束密度Ｂｇは、プレート１１０の厚さＬｐに依らず同じ推移で、略線形的に増加する。 As shown in FIG. 4, when the thickness Lm of the magnet 130 is smaller than 7 mm, the magnetic flux density Bg increases substantially linearly with the same transition regardless of the thickness Lp of the plate 110.
　磁石１３０の厚さＬｍが７ｍｍより大きくなると、磁束密度Ｂｇは、プレート１１０の厚さＬｐ毎に異なる推移を示す。このとき、磁束密度Ｂｇの推移は、プレート１１０の厚さＬｐが大きいほど、低い値の推移となっている。 When the thickness Lm of the magnet 130 is greater than 7 mm, the magnetic flux density Bg shows different transitions for each thickness Lp of the plate 110. At this time, the transition of the magnetic flux density Bg becomes a lower transition as the thickness Lp of the plate 110 is larger.
　そして、磁石１３０の厚さＬｍが更に大きくなると、磁束密度Ｂｇは、やがて飽和する。磁束密度Ｂｇが飽和領域に移行し始めるときの磁石１３０の厚さＬｍは、プレート１１０の厚さＬｐによって異なる。具体的には、磁束密度Ｂｇが飽和領域に移行し始める点は、Ｌｐ＝３ｍｍでＬｍ＝１４ｍｍ（図４の点Ａ）、Ｌｐ＝５ｍｍでＬｍ＝１２ｍｍ（図４の点Ｂ）、Ｌｐ＝７ｍｍでＬｍ＝１０ｍｍ（図４の点Ｃ）、Ｌｐ＝９ｍｍでＬｍ＝７ｍｍ（図４の点Ｄ）である。 Then, when the thickness Lm of the magnet 130 is further increased, the magnetic flux density Bg is eventually saturated. The thickness Lm of the magnet 130 when the magnetic flux density Bg starts to shift to the saturation region varies depending on the thickness Lp of the plate 110. Specifically, the points where the magnetic flux density Bg starts to shift to the saturation region are Lp = 3 mm, Lm = 14 mm (point A in FIG. 4), Lp = 5 mm, Lm = 12 mm (point B in FIG. 4), Lp = At 7 mm, Lm = 10 mm (point C in FIG. 4), and at Lp = 9 mm, Lm = 7 mm (point D in FIG. 4).
　磁気回路１００では、磁石１３０の厚さＬｍを点Ａ～Ｄより大きくしても、磁束密度Ｂｇの増加率が非常に小さい。磁気回路１００では、点Ａ～Ｄより大きくした厚さＬｍの部分は無駄となり、磁石１３０の使用効率が悪い。点Ａ～Ｄは、プレート１１０の厚さＬｐ毎で、磁石１３０の使用効率の良し悪しを判断するための閾値となる。磁気回路１００では、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐを点Ａ～Ｄの値に近付けると、磁石１３０の使用効率が良くなる。 In the magnetic circuit 100, even if the thickness Lm of the magnet 130 is larger than the points A to D, the increasing rate of the magnetic flux density Bg is very small. In the magnetic circuit 100, the portion of the thickness Lm larger than the points A to D is wasted, and the use efficiency of the magnet 130 is poor. Points A to D serve as threshold values for determining whether the use efficiency of the magnet 130 is good or not for each thickness Lp of the plate 110. In the magnetic circuit 100, when the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are brought close to the values of the points A to D, the use efficiency of the magnet 130 is improved.
　図５は、本発明の一実施形態に係る磁気回路１００が有する磁石１３０のパーミアンス係数Ｐｃを示すグラフである。
　図５の縦軸は、磁石１３０のパーミアンス係数Ｐｃであり、図５の横軸は、磁石１３０の厚さＬｍである。
　図５の曲線は、プレート１１０の厚さＬｐ毎に磁石１３０の厚さＬｍを変化させたときの、磁石１３０の厚さＬｍと磁石１３０のパーミアンス係数Ｐｃとの関係を示している。 FIG. 5 is a graph showing the permeance coefficient Pc of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
The vertical axis in FIG. 5 is the permeance coefficient Pc of the magnet 130, and the horizontal axis in FIG. 5 is the thickness Lm of the magnet 130.
The curve in FIG. 5 shows the relationship between the thickness Lm of the magnet 130 and the permeance coefficient Pc of the magnet 130 when the thickness Lm of the magnet 130 is changed for each thickness Lp of the plate 110.
　図５に示すように、パーミアンス係数Ｐｃは、プレート１１０の厚さＬｐ毎に異なる推移で、略線形的に増加する。パーミアンス係数Ｐｃの推移は、プレート１１０の厚さＬｐが大きいほど、高い値の推移となっている。 As shown in FIG. 5, the permeance coefficient Pc increases approximately linearly with different transitions for each thickness Lp of the plate 110. The transition of the permeance coefficient Pc increases as the thickness Lp of the plate 110 increases.
　単純にパーミアンス係数Ｐｃを高めるだけであれば、磁石１３０の厚さＬｍ等を厚くすればよい。しかし、図４で示したように、磁石１３０の厚さＬｍを磁束密度Ｂｇが飽和する点Ａ～Ｄより大きい場合、磁石１３０の厚さＬｍの増加が磁気ギャップＧの磁束密度Ｂｇの増加に寄与し難い。 If the permeance coefficient Pc is simply increased, the thickness Lm of the magnet 130 may be increased. However, as shown in FIG. 4, when the thickness Lm of the magnet 130 is larger than the points A to D at which the magnetic flux density Bg saturates, the increase in the thickness Lm of the magnet 130 increases the magnetic flux density Bg of the magnetic gap G. Hard to contribute.
　図５には、図４で示した磁束密度Ｂｇが飽和する点Ａ～Ｄをプロットしている。点Ａ～Ｄは、いずれもパーミアンス係数ＰｃがＰｃ＝１８以上２２以下の範囲（図５の一点鎖線間の網掛部）に有る。よって、磁気回路１００では、磁石１３０の動作点ｄがパーミアンス係数Ｐｃ＝１８以上２２以下の範囲にあれば、磁石１３０の使用効率が良いことが分かる。 FIG. 5 plots points A to D where the magnetic flux density Bg shown in FIG. 4 is saturated. The points A to D are all within the range where the permeance coefficient Pc is Pc = 18 or more and 22 or less (shaded portion between the chain lines in FIG. 5). Therefore, in the magnetic circuit 100, it can be seen that if the operating point d of the magnet 130 is in the range of the permeance coefficient Pc = 18 or more and 22 or less, the use efficiency of the magnet 130 is good.
　図６は、本発明の一実施形態に係る磁気回路１００が有する磁石１３０の動作点ｄを説明するための図である。
　図６の曲線は、磁石１３０の構成材料であるＦｅ－Ｃｒ－Ｃｏ系磁石の減磁曲線であり、図３の減磁曲線と同一である。
　図６の曲線は、図５で示したパーミアンス係数Ｐｃと図３で示した減磁曲線との関係を示している。 FIG. 6 is a diagram for explaining the operating point d of the magnet 130 included in the magnetic circuit 100 according to the embodiment of the present invention.
The curve in FIG. 6 is a demagnetization curve of an Fe—Cr—Co based magnet that is a constituent material of the magnet 130, and is the same as the demagnetization curve in FIG.
The curve in FIG. 6 shows the relationship between the permeance coefficient Pc shown in FIG. 5 and the demagnetization curve shown in FIG.
　図６に示すように、磁石１３０のパーミアンス係数ＰｃがＰｃ＝１８以上２２以下の範囲である場合、磁石１３０の動作点ｄは、屈曲点Ｋより残留磁束密度Ｂｒ側に位置し、且つ、屈曲点Ｋの近傍に位置している。言い換えると、動作点ｄが屈曲点Ｋより残留磁束密度Ｂｒ側で、且つ、屈曲点Ｋ近傍に位置するような、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐとするためには、Ｐｃ＝１８以上２２以下が好適であることが分かる。 As shown in FIG. 6, when the permeance coefficient Pc of the magnet 130 is in the range of Pc = 18 or more and 22 or less, the operating point d of the magnet 130 is located on the residual magnetic flux density Br side from the bending point K, and It is located in the vicinity of the point K. In other words, in order to obtain the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 such that the operating point d is located on the residual magnetic flux density Br side of the bending point K and in the vicinity of the bending point K, Pc It turns out that = 18 or more and 22 or less are suitable.
　図７は、本発明の一実施形態に係る磁気回路１００が有する磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの関係を示すグラフである。
　図７の縦軸は、磁石１３０の厚さＬｍであり、図７の横軸は、プレート１１０の厚さＬｐである。
　図７の曲線は、磁石１３０のパーミアンス係数ＰｃがＰｃ＝１８以上２２以下である場合の、磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの関係を示している。 FIG. 7 is a graph showing the relationship between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 included in the magnetic circuit 100 according to the embodiment of the present invention.
The vertical axis in FIG. 7 is the thickness Lm of the magnet 130, and the horizontal axis in FIG. 7 is the thickness Lp of the plate 110.
The curve in FIG. 7 shows the relationship between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 when the permeance coefficient Pc of the magnet 130 is Pc = 18 or more and 22 or less.
　図７に示すように、磁石１３０のパーミアンス係数ＰｃがＰｃ＝１８以上２２以下である場合、磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの関係は、略反比例の関係にある。磁石１３０のパーミアンス係数ＰｃがＰｃ＝１８以上２２以下である場合に、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐが取り得る範囲は、少なくとも、図７の曲線で囲まれる範囲Ｓ（図７の網掛部）に分布している。
　言い換えると、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐを、少なくとも範囲Ｓ内の点にすると、磁石１３０の動作点ｄは、屈曲点Ｋより残留磁束密度Ｂｒ側で、且つ、屈曲点Ｋ近傍に位置することができる。このような動作点ｄで作動する磁石１３０では、磁束密度Ｂｄが高く、且つ、磁石の使用効率が高い。すなわち、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐを、少なくとも範囲Ｓ内の点にすると、所望の磁束密度Ｂｇを得るために必要な磁石の量を最小限とすることができる。
　したがって、上記磁気特性の磁石１３０を有する磁気回路１００において、磁石の使用効率と磁束密度Ｂｇとの両立を図るためには、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐを、少なくとも範囲Ｓ内の点にすればよい。 As shown in FIG. 7, when the permeance coefficient Pc of the magnet 130 is Pc = 18 or more and 22 or less, the relationship between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is substantially inversely proportional. When the permeance coefficient Pc of the magnet 130 is Pc = 18 or more and 22 or less, the possible range of the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is at least a range S (see FIG. 7).
In other words, when the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are at least points within the range S, the operating point d of the magnet 130 is closer to the residual magnetic flux density Br than the bending point K and the bending point. It can be located near K. In the magnet 130 operating at such an operating point d, the magnetic flux density Bd is high and the use efficiency of the magnet is high. That is, when the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are at least points in the range S, the amount of magnets necessary to obtain the desired magnetic flux density Bg can be minimized.
Therefore, in the magnetic circuit 100 having the magnet 130 having the above magnetic characteristics, in order to achieve both the use efficiency of the magnet and the magnetic flux density Bg, the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 are set to at least the range S. What is necessary is just to be a point inside.
　図７に示すように、範囲Ｓ内の点は、磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの比が、少なくとも、Ｌｍ：Ｌｐ＝７：９（図７の点α）以上であり、Ｌｍ：Ｌｐ＝１６：３（図７の点β）以下である。
　よって、磁石１３０の厚さＬｍとプレート１１０の厚さＬｐとの比を、少なくともＬｍ：Ｌｐ＝７：９以上１６：３以下とすれば、磁石の使用効率と磁束密度Ｂｇとの両立を図ることができる。図７の例では、プレート１１０の厚さＬｐが３ｍｍ以上９ｍｍ以下の範囲にあり、磁石１３０の厚さＬｍが７ｍｍ以上１６ｍｍ以下の範囲にあれば、磁石の使用効率と磁束密度Ｂｇとの両立を図ることができる。
　なお、ボイスコイル２０のインピーダンスを４Ωとする場合、Ｌｍ：Ｌｐ＝１：１以上３：１以下とすれば、更に好適である。 As shown in FIG. 7, the points within the range S are such that the ratio of the thickness Lm of the magnet 130 to the thickness Lp of the plate 110 is at least Lm: Lp = 7: 9 (point α in FIG. 7). Yes, Lm: Lp = 16: 3 (point β in FIG. 7) or less.
Therefore, if the ratio between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is at least Lm: Lp = 7: 9 or more and 16: 3 or less, both the magnet usage efficiency and the magnetic flux density Bg are achieved. be able to. In the example of FIG. 7, if the thickness Lp of the plate 110 is in the range of 3 mm to 9 mm and the thickness Lm of the magnet 130 is in the range of 7 mm to 16 mm, both the magnet use efficiency and the magnetic flux density Bg are compatible. Can be achieved.
When the impedance of the voice coil 20 is 4Ω, it is more preferable that Lm: Lp = 1: 1 to 3: 1.
　本実施形態では、Ｆｅ－Ｃｒ－Ｃｏ系磁石を構成材料とする磁石１３０を用いて、内磁型の磁気回路１００を構成した。加えて、本実施形態では、磁石１３０の厚さＬｍ及びプレート１１０の厚さＬｐの比を最適化した。
　このため、本実施形態の磁気回路１００は、ネオジム系磁石等の高価な磁石を用いずとも、磁石の小径化及び軽量化が可能であり、且つ、高い使用効率の磁石にて所望の磁束密度Ｂｇを得ることができる。よって、本実施形態によれば、小径且つ軽量であり、磁石の使用効率及び磁束密度の両立が可能である安価な磁気回路１００を提供することができる。そして、本実施形態によれば、このような小型・高性能で安価な磁気回路１００を搭載したスピーカー装置１を提供することができる。 In the present embodiment, the inner-magnet-type magnetic circuit 100 is configured using the magnet 130 made of a Fe—Cr—Co-based magnet. In addition, in this embodiment, the ratio between the thickness Lm of the magnet 130 and the thickness Lp of the plate 110 is optimized.
For this reason, the magnetic circuit 100 of the present embodiment can reduce the diameter and weight of the magnet without using an expensive magnet such as a neodymium magnet, and can achieve a desired magnetic flux density with a magnet with high use efficiency. Bg can be obtained. Therefore, according to this embodiment, it is possible to provide an inexpensive magnetic circuit 100 that is small in diameter and light in weight, and that can achieve both the use efficiency of the magnet and the magnetic flux density. And according to this embodiment, the speaker apparatus 1 carrying such a small, high performance, and inexpensive magnetic circuit 100 can be provided.
　以上の実施形態は、本発明の好適な実施形態の例であるが、本発明は、これに限定されるものではなく、発明の要旨を逸脱しない範囲で、種々の変形又は変更が可能である。 The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications or changes can be made without departing from the scope of the invention. .
　本実施形態では、スピーカー装置１は、振動板１０の形状が、いわゆるドーム型のスピーカー装置を示した。他の例としては、スピーカー装置１が、コーン型スピーカー装置、ホーン型スピーカー装置、平面型スピーカー装置、平板型スピーカー装置、又はハイル型スピーカー装置であってもよい。 In the present embodiment, the speaker device 1 is a so-called dome-shaped speaker device in which the diaphragm 10 has a shape. As another example, the speaker device 1 may be a cone speaker device, a horn speaker device, a flat speaker device, a flat speaker device, or a Heil speaker device.
　本実施形態では、振動板１０は、金属材料、樹脂材料、繊維材料、又はこれらの混合材料で形成されている。振動板１０を形成する金属材料は、例えば、アルミニウム、チタニウム、ベリリウム、マグウネシウム、ボロン、又はこれらの合金等である。振動板１０を形成する樹脂材料は、例えば、ポリプロピレン、ポリエチレン、ポリスチレン、ポリエチレンテレフタレート、エポキシ等である。振動板１０を形成する繊維材料は、例えば、サルファイトパルプ、クラフトパルプの混合繊維等である。 In this embodiment, the diaphragm 10 is formed of a metal material, a resin material, a fiber material, or a mixed material thereof. The metal material forming the diaphragm 10 is, for example, aluminum, titanium, beryllium, magnesium, boron, or an alloy thereof. The resin material forming the diaphragm 10 is, for example, polypropylene, polyethylene, polystyrene, polyethylene terephthalate, epoxy, or the like. The fiber material forming the diaphragm 10 is, for example, a mixed fiber of sulfite pulp or kraft pulp.
　また、本実施形態では、振動板１０の振動部１１、ダンパ部１２、及びエッジ部１３が、一体成形されているとした。他の例としては、ダンパ部１２及びエッジ部１３を、振動部１１とは別体の別材料で形成してもよい。 Further, in the present embodiment, it is assumed that the vibration part 11, the damper part 12, and the edge part 13 of the diaphragm 10 are integrally formed. As another example, the damper portion 12 and the edge portion 13 may be formed of a separate material different from the vibrating portion 11.
　　　　１　　　スピーカー装置
　　　１０　　　振動板
　　　１１　　　振動部
　　　２０　　　ボイスコイル
　　　２１　　　ボイスコイルボビン
　　　３０　　　フレーム
　　１００　　　磁気回路
　　１１０　　　プレート
　　１２０　　　ヨーク
　　１３０　　　磁石 DESCRIPTION OF SYMBOLS 1 Speaker apparatus 10 Diaphragm 11 Vibrating part 20 Voice coil 21 Voice coil bobbin 30 Frame 100 Magnetic circuit 110 Plate 120 Yoke 130 Magnet

Claims (17)

  1. 　Ｆｅ－Ｃｒ－Ｃｏ系磁石と、
    　前記磁石の一極側に設けられたプレートと、
    　前記磁石の他極側に設けられたヨークと、
    　前記プレートと前記ヨークとの間に形成された磁気ギャップと、
    　を少なくとも有する
    　スピーカー装置用磁気回路。     An Fe-Cr-Co magnet,
    A plate provided on one pole side of the magnet;
    A yoke provided on the other pole side of the magnet;
    A magnetic gap formed between the plate and the yoke;
    A magnetic circuit for a speaker device.
  2. 　前記磁石の磁化方向の厚さと、該磁化方向での前記プレートの厚さとの比が、７：９以上１６：３以下である
    　請求項１に記載の内磁型のスピーカー装置用磁気回路。     The magnetic circuit for an internal magnet type speaker device according to claim 1, wherein a ratio of a thickness in the magnetization direction of the magnet to a thickness of the plate in the magnetization direction is 7: 9 or more and 16: 3 or less.
  3. 　前記磁石のパーミアンス係数が、１８以上２２以下である
    　請求項２に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 2, wherein a permeance coefficient of the magnet is 18 or more and 22 or less.
  4. 　前記磁石のＢ－Ｈ曲線上の動作点における磁束密度の大きさは、該磁石のＢ－Ｈ曲線上の屈曲点における磁束密度の大きさ以上である
    　請求項３に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 3, wherein the magnitude of the magnetic flux density at the operating point on the BH curve of the magnet is equal to or greater than the magnitude of the magnetic flux density at the bending point on the BH curve of the magnet. .
  5. 　前記磁石の磁化方向の厚さは、前記磁気ギャップの磁束密度が飽和領域になる厚さ以下である
    　請求項３に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 3, wherein a thickness of the magnet in a magnetization direction is equal to or less than a thickness at which a magnetic flux density of the magnetic gap becomes a saturation region.
  6. 　前記プレートは、その厚さが略均一な略円柱形状に形成されており、
    　前記プレートの前記磁石側の底面が、前記磁石の一極側と磁気的に接合している
    　請求項３に記載のスピーカー装置用磁気回路。     The plate is formed in a substantially cylindrical shape having a substantially uniform thickness,
    The magnetic circuit for a speaker device according to claim 3, wherein a bottom surface of the plate on the magnet side is magnetically joined to one pole side of the magnet.
  7. 　前記磁化方向での前記プレートの厚さは、３ｍｍ以上９ｍｍ以下である
    　請求項６に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 6, wherein the thickness of the plate in the magnetization direction is 3 mm or more and 9 mm or less.
  8. 　前記ヨークは、
    　略円板形状の底部と、
    　前記底部から前記磁化方向に沿って延出する略円筒形状の側部と、
    　を有し、
    　前記側部の延出長さは、前記磁石の磁化方向の厚さと該磁化方向での前記プレートの厚さとの和に、略等しい
    　請求項３に記載のスピーカー装置用磁気回路。     The yoke is
    A substantially disk-shaped bottom;
    A substantially cylindrical side extending from the bottom along the magnetization direction;
    Have
    The magnetic circuit for a speaker device according to claim 3, wherein an extension length of the side portion is substantially equal to a sum of a thickness in a magnetization direction of the magnet and a thickness of the plate in the magnetization direction.
  9. 　前記ヨークは、
    　略円板形状の底部と、
    　前記底部から前記磁化方向に沿って延出する略円筒形状の側部と、
    　を有し、
    　前記プレートの前記磁石側と反対側の底面と、前記側部の延出先端の端面とが、略同一平面上にある
    　請求項３に記載のスピーカー装置用磁気回路。     The yoke is
    A substantially disk-shaped bottom;
    A substantially cylindrical side extending from the bottom along the magnetization direction;
    Have
    The magnetic circuit for a speaker device according to claim 3, wherein a bottom surface of the plate opposite to the magnet side and an end surface of the extending tip of the side portion are on substantially the same plane.
  10. 　前記磁石は、その厚さが略均一な略円柱形状に形成されており、
    　前記磁石の各底面は、互いに異なる磁極をそれぞれ有し、
    　前記磁化方向は、前記磁石の各底面の一方側から該各底面の他方側へ向かう方向である
    　請求項７又は８に記載のスピーカー装置用磁気回路。     The magnet is formed in a substantially cylindrical shape having a substantially uniform thickness,
    Each bottom surface of the magnet has a different magnetic pole,
    The magnetic circuit for a speaker device according to claim 7 or 8, wherein the magnetization direction is a direction from one side of each bottom surface of the magnet toward the other side of each bottom surface.
  11. 　前記磁石の各底面の一方側の底面は、前記プレートの前記磁石側の底面と磁気的に接合し、
    　前記磁石の各底面の他方側の底面は、前記ヨークの前記底部と磁気的に接合する
    　請求項１０に記載のスピーカー装置用磁気回路。     The bottom surface on one side of each bottom surface of the magnet is magnetically bonded to the bottom surface on the magnet side of the plate,
    The magnetic circuit for a speaker device according to claim 10, wherein a bottom surface on the other side of each bottom surface of the magnet is magnetically joined to the bottom portion of the yoke.
  12. 　前記磁石の外径の大きさは、前記プレートの外径の大きさ以下である
    　請求項１１に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 11, wherein the outer diameter of the magnet is equal to or smaller than the outer diameter of the plate.
  13. 　前記磁石の磁化方向の厚さは、７ｍｍ以上１６ｍｍ以下である
    　請求項１２に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 12, wherein a thickness of the magnet in a magnetization direction is 7 mm or more and 16 mm or less.
  14. 　前記磁石と前記プレートと前記側部とは、略同心円に配置されている
    　請求項１３に記載のスピーカー装置用磁気回路。     The magnetic circuit for a speaker device according to claim 13, wherein the magnet, the plate, and the side portion are arranged substantially concentrically.
  15. 　請求項１乃至３のいずれかに記載のスピーカー装置用磁気回路を有し、
    　前記磁気ギャップ内に配置されたボイスコイルと、
    　前記ボイスコイルが巻回されたボイスコイルボビンと、
    　前記ボイスコイルボビンに接続された振動板と、
    　を有するスピーカー装置。     A magnetic circuit for a speaker device according to any one of claims 1 to 3,
    A voice coil disposed within the magnetic gap;
    A voice coil bobbin around which the voice coil is wound;
    A diaphragm connected to the voice coil bobbin;
    A speaker device.
  16. 　前記ボイスコイルボビンは、略円筒形状に形成されており、
    　前記ボイスコイルボビンと前記プレートとは、略同心円に配置されている
    　請求項１５に記載のスピーカー装置。     The voice coil bobbin is formed in a substantially cylindrical shape,
    The speaker device according to claim 15, wherein the voice coil bobbin and the plate are arranged in a substantially concentric circle.
  17. 　前記ボイスコイルは、前記ボイスコイルボビンの外周に巻回されており、
    　前記ボイスコイルの巻幅の前記磁化方向での中央位置は、該磁化方向での前記プレートの厚さの中央位置と、該磁化方向で略同一の位置にある
    　請求項１６に記載のスピーカー装置。     The voice coil is wound around the outer periphery of the voice coil bobbin,
    The speaker device according to claim 16, wherein a central position of the winding width of the voice coil in the magnetization direction is substantially the same position in the magnetization direction as a central position of the thickness of the plate in the magnetization direction.
PCT/JP2012/058432 2012-03-29 2012-03-29 Magnetic circuit for speaker device and speaker device WO2013145227A1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016052079A (en) * 2014-09-02 2016-04-11 パナソニックＩｐマネジメント株式会社 Loudspeaker
EP3190806A4 (en) * 2014-09-01 2018-03-28 Panasonic Intellectual Property Management Co., Ltd. Loudspeaker
JP2021063242A (en) * 2019-10-10 2021-04-22 マグネデザイン株式会社 Stainless magnet

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JPH0851693A (en) * 1994-05-30 1996-02-20 Matsushita Electric Ind Co Ltd Magnetic circuit unit for microspeaker and its manufacture
JPH08223693A (en) * 1995-02-17 1996-08-30 Shichizun Denshi:Kk Surface mounting type electromagnetic sounding body
JPH11100646A (en) * 1997-09-24 1999-04-13 Alps Electric Co Ltd Hard magnetic material and production of hard magnetic material
JP2007306214A (en) * 2006-05-10 2007-11-22 Fujitsu Ten Ltd Speaker magnetic circuit

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0851693A (en) * 1994-05-30 1996-02-20 Matsushita Electric Ind Co Ltd Magnetic circuit unit for microspeaker and its manufacture
JPH08223693A (en) * 1995-02-17 1996-08-30 Shichizun Denshi:Kk Surface mounting type electromagnetic sounding body
JPH11100646A (en) * 1997-09-24 1999-04-13 Alps Electric Co Ltd Hard magnetic material and production of hard magnetic material
JP2007306214A (en) * 2006-05-10 2007-11-22 Fujitsu Ten Ltd Speaker magnetic circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3190806A4 (en) * 2014-09-01 2018-03-28 Panasonic Intellectual Property Management Co., Ltd. Loudspeaker
JP2016052079A (en) * 2014-09-02 2016-04-11 パナソニックＩｐマネジメント株式会社 Loudspeaker
JP2021063242A (en) * 2019-10-10 2021-04-22 マグネデザイン株式会社 Stainless magnet

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