JP2013255087A - Magnetic circuit and electrodynamic speaker employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic circuit in which a magnetic flux density is increased, sound reproduction efficiency is improved and a magnetic flux to be leaked to the outside is reduced even when using a resin magnet with which a magnetic flux density in a magnetic gap is easy to decrease, and an electrodynamic speaker employing the same.SOLUTION: A magnetic circuit for an electrodynamic speaker comprises a magnet which has an annular base specified by a first plane and a second plane which are parallel to each other, an annular plate whose lower surface is connected to the first plane, and a pole including a columnar part forming a magnetic gap between an under plate part connected the second plane and the plate. The magnet is magnetized to have polarities different from each other at a side of the first plane and at a side of the second plane. In a first range in a radial direction of the base, the magnet is oriented and magnetized in an orthogonal direction which is orthogonal to the first plane and the second plane and in a second range in the radial direction different from the first range of the base, the magnet is oriented and magnetized in a direction different from the orthogonal direction.

Description

  More particularly, the present invention relates to a magnetic circuit using a resin magnet and an electrodynamic speaker using the same.

  In an electrodynamic speaker that reproduces sound, it is desired to increase the reproduction efficiency of converting an electric sound signal into a sound wave including an energy saving viewpoint. Various magnets such as ferrite magnets, alnico magnets, or resin magnets are used as magnets for magnetic circuits for speakers. In particular, in recent electrodynamic speakers, when miniaturization and weight reduction are required, neodymium magnets mainly composed of neodymium, iron, and boron, which have a large magnetomotive force, are used as magnetic circuit magnets. There is a case where the magnetic flux density in the air gap is to be increased. Since rare earth magnets such as neodymium magnets and samarium cobalt magnets are magnets that use resources that are unevenly distributed as rare earth magnets, their prices have recently increased due to increasing demand.

  Other rare earth magnets include resin magnets and bond magnets containing magnetic powder of samarium iron nitride (Sm-Fe-N). Since samarium iron nitride is weak to heat and difficult to use the powder sintering method, it is used as a bond magnet that mixes powder mainly with resin. Since samarium iron nitride resin magnets do not contain cobalt, the raw material cost is relatively low, and it has the advantage of being easily resin-molded into any shape, so it may be used as a magnetic circuit for electrodynamic speakers. is there. Conventionally, there is a magnetic circuit for a speaker including a resin magnet using a magnetic powder of a ferrite magnet as the magnetic powder.

  For example, conventionally, a frame; a magnetic circuit having a plate integrally formed with the frame; a pole; and a magnet; a voice coil; an integral with the voice coil, and a peripheral portion of the frame. A speaker, and a magnet that forms a magnetic field and adheres the pole and the plate. The magnet includes an Sm-Fe-N magnet and a binder resin. There is a speaker including (Patent Document 1).

  Further, conventionally, in a plate-like magnet having at least one plane as an action surface, the easy axis of magnetization of the magnetic powder constituting the magnet passes from the main pole at the center of the action surface to the inside of the magnet, and on the action surface. The magnet for electro-magnetoacoustic conversion, characterized in that it is curved and oriented on the side opposite to the opposite pole and the non-working surface and the surface opposite to the working surface, and using this magnet There is an electric-magnetoacoustic transducer (Patent Document 2). Alternatively, it is a long magnet in which a region of action formed in at least one region of a contour line in a cross section perpendicular to the longitudinal direction is provided in the longitudinal direction, and the magnetization easy axis of the magnetic powder in the cross section is the function An electro-magnetoacoustic conversion magnet characterized by being oriented so as to return from one area in the area to the other area in the working area through the inside of the magnet, and using this magnet There is an electro-magneto-acoustic transducer (Patent Document 3).

JP 2002-218589 A JP 2002-218582 A JP 2003-23694 A

  However, a magnetic circuit using a resin magnet and an electrodynamic speaker using the same have a problem that the magnetic flux density in the magnetic gap of the magnetic circuit tends to be low, and the efficiency of sound reproduction is low. Further, if the ratio of the magnetic powder of the resin magnet is increased and the ratio of the resin is decreased to increase the magnetic flux density, there is a problem that it becomes difficult to mold at the time of manufacturing the resin magnet.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention relates to a magnetic circuit and an electrodynamic speaker including the magnetic circuit, and in particular, a magnetic flux density in a magnetic gap is reduced. An object of the present invention is to provide a magnetic circuit that increases the magnetic flux density to improve the efficiency of sound reproduction and lowers the leakage magnetic flux to the outside, and an electrodynamic speaker using the magnetic circuit, even when using an easy resin magnet.

  The magnetic circuit of the present invention includes a magnet having an annular base defined by a first plane and a second plane parallel to each other, an annular plate whose lower surface is coupled to the first plane, and a second plane. A magnetic circuit for an electrodynamic loudspeaker comprising: an under plate portion and a pole including a columnar portion that passes through a circular hole of the magnet and forms a magnetic gap between the magnet and the first plane And the second plane side are magnetized so as to have different magnetic polarities, and in the first range in the radial direction of the substrate, oriented magnetization is performed in an orthogonal direction perpendicular to the first plane and the second plane. In the second range in the radial direction different from the first range of the base body, orientation magnetization is performed in a direction different from the orthogonal direction.

  In the magnetic circuit of the present invention, the second range of the magnet is provided in a predetermined range including the outer peripheral end of the base and / or the inner peripheral end of the base.

  Moreover, the magnetic circuit of this invention is a resin magnet in which a magnet contains magnetic powder and resin which contains a magnetic powder and forms a base | substrate.

  In the magnetic circuit of the present invention, the outer diameter of the base of the magnet is larger than the outer diameter of the underplate portion of the plate and the pole, and the second range of the magnet includes the outer peripheral end of the base. And it is provided in the range which protruded to the outer peripheral side rather than the underplate part.

  In the magnetic circuit of the present invention, the underplate portion of the pole has an inner diameter end that defines a groove portion with the columnar portion, the inner diameter dimension of the magnet is larger than the inner diameter dimension of the plate, and the pole The second range of the magnet is provided in a predetermined range including the inner peripheral side end portion of the base body, being substantially equal to the inner diameter size of the inner diameter end of the under plate portion.

  In the magnetic circuit of the present invention, in the second range of the magnet, the magnetization direction to be oriented and magnetized is restricted to a direction intersecting with the orthogonal direction within a range of ± 45 degrees, and the first plane and the second plane Is oriented and magnetized so that the absolute value of the difference in the direction angle of the magnetization direction is large in the range close to, and the direction angle of the magnetization direction is in the range near the center of the thickness of the substrate far from the first plane and the second plane. Oriented and magnetized so that the absolute value of the difference is small.

  An electrodynamic speaker according to the present invention includes the above magnetic circuit, a frame having a magnetic circuit fixing portion for fixing the magnetic circuit, a voice coil having a coil disposed in a magnetic gap of the magnetic circuit, and a voice coil. A speaker diaphragm connected at the center side, an edge connected to the outer peripheral end side of the speaker diaphragm and the edge fixing portion of the frame, and a damper connected to the damper fixing portion of the voice coil and the frame.

  The operation of the present invention will be described below.

  The magnetic circuit of the present invention includes a magnet having an annular base defined by a first plane and a second plane parallel to each other, an annular plate whose lower surface is coupled to the first plane, and a second plane. And a pole including a columnar portion that forms a magnetic gap between the under plate portion and the circular hole of the magnet and the plate. That is, in this magnetic circuit, the magnet is magnetized so that the first plane side and the second plane side have different magnetic polarities, and the magnet is defined on the inner peripheral side of the annular base of the magnet. This is an external magnetic circuit that forms a DC magnetic field in the air gap.

  An electrodynamic speaker according to the present invention includes a magnetic circuit, a frame having a magnetic circuit fixing portion for fixing the magnetic circuit, a voice coil having a coil disposed in a magnetic gap of the magnetic circuit, and a voice coil at the center. An electrodynamic speaker comprising: a speaker diaphragm connected on the side; an edge connected to an outer peripheral end of the speaker diaphragm and an edge fixing portion of the frame; and a damper connected to a damper fixing portion of the voice coil and the frame. is there. In an electrodynamic speaker, when an audio signal is supplied to a coil of a voice coil arranged in a magnetic gap, a driving force is generated to vibrate the speaker diaphragm and convert the electric signal into a sound wave. .

  The magnet of the magnetic circuit is preferably a resin magnet including magnetic powder and a resin that includes the magnetic powder and forms a base. For example, the resin magnet may be a magnetic powder of a ferrite magnet or a bonded magnet in which a magnetic powder of samarium iron nitride (Sm—Fe—N) is contained in a resin. The magnet of the magnetic circuit is oriented and magnetized in the orthogonal direction orthogonal to the first plane and the second plane in the first range in the radial direction of the base, and the second range in the radial direction different from the first range of the base. Then, it is oriented and magnetized by bending in a direction different from the orthogonal direction. The second range of the magnet is provided in a predetermined range including the outer peripheral end of the base and / or the inner peripheral end of the base, and the first range of the magnet corresponds to a portion other than the second range. In other words, the magnet of this magnetic circuit is oriented and polarized in a direction different from the orthogonal direction and the first range where the orientation magnetization is oriented and magnetized in the orthogonal direction according to the radial position of the substrate. The second range is changed to the magnetized second range.

  Specifically, the second range of the magnet is such that the outer diameter of the base of the magnet is larger than the outer diameter of the underplate portion of the plate and the pole, and the second range of the magnet has the outer peripheral side end of the base. It is provided in the range which protruded to the outer peripheral side rather than the plate and the underplate part. Alternatively, the underplate portion of the pole has an inner diameter end that defines a groove portion with the columnar portion, the inner diameter size of the magnet is larger than the inner diameter size of the plate, and the inner diameter end of the underplate portion of the pole When it is substantially equal to the inner diameter, the second range of the magnet may be provided in a predetermined range including the inner peripheral end of the base. In such cases, in the second range of the magnet, it is preferable that the orientation and magnetization direction is restricted to a direction intersecting with the orthogonal direction within a range of ± 45 degrees.

  That is, the magnetic field lines passing through the second range of the magnet of the magnetic circuit are oriented so that the absolute value of the difference in the direction angle of the magnetization direction is large in the range close to the first plane and the second plane so that the magnetic field lines swell to the outer peripheral side. Preferably, the magnet is oriented and magnetized so that the absolute value of the difference in the direction angle in the magnetization direction is small in the vicinity of the center of the thickness of the substrate that is magnetized and is far from the first plane and the second plane. By doing so, in the second range on the outer peripheral side and / or the inner peripheral side of the magnetic circuit, the leakage magnetic flux leaking to the space outside the magnetic circuit passes through the magnetic circuit. In this case, the magnetic flux density is increased and the leakage magnetic flux is reduced. As a result, the electrodynamic loudspeaker using the magnetic circuit of the present invention can increase the magnetic flux density and improve the sound reproduction efficiency even when using a resin magnet that tends to lower the magnetic flux density in the magnetic gap.

  With regard to a magnetic circuit and an electrodynamic speaker using the magnetic circuit, in particular, even when using a resin magnet that tends to reduce the magnetic flux density in the magnetic gap, the magnetic flux density is increased to improve the sound reproduction efficiency, Leakage magnetic flux can be lowered.

It is sectional drawing explaining the electrodynamic speaker 1 by preferable embodiment of this invention. Example 1 It is sectional drawing explaining the magnetic circuit 10 of the electrodynamic speaker by preferable embodiment of this invention. Example 1

  Hereinafter, a magnetic circuit and an electrodynamic speaker according to preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

  FIG. 1 is a diagram illustrating an electrodynamic speaker 1 according to a preferred embodiment of the present invention. FIG. 2 is a diagram illustrating the magnetic circuit 10 of the electrodynamic speaker 1. Specifically, FIG. 1 is a cross-sectional view of the electrodynamic speaker 1 corresponding to an OA cross section in which the right half side is omitted from the central axis passing through the central point, and FIG. FIG. 2B is a partially enlarged view of the magnet 12. As will be described later, a part of the structure of the electrodynamic speaker 1, the internal structure, and the like are omitted.

  The electrodynamic speaker 1 of the present embodiment is an electrodynamic speaker having a circular speaker diaphragm 2 having a diameter of about 16 cm, and is used for a vehicle that is reduced in weight so as to be attached to a vehicle body (not shown). It is a speaker. The cone-shaped speaker diaphragm 2 is supported at its outer peripheral edge by an edge 3. The speaker diaphragm 2 of the present embodiment is a paper material to be made of paper, but may be composed of other materials. The outer peripheral end of the roll-shaped edge 3 is fixed to a resin frame 7, and a gasket is attached to the front side thereof. The inner peripheral end of the edge 3 is connected to the outer peripheral end of the speaker diaphragm 2. A voice coil 4 is connected to the center of the speaker diaphragm 2 from the back side. The voice coil 4 is supported by a damper 5 so that the coil bobbin can vibrate. The damper 5 is a corrugation damper that is formed by impregnating a phenol resin with a woven fabric of flexible fibers as a base material, and an outer peripheral end thereof is fixed to the frame 7.

  The voice coil 4 has a coil wound around one end of a cylindrical coil bobbin, and this coil is disposed in the magnetic gap of the magnetic circuit 10 fixed to the frame 7. The tinsel wire (not shown) connected to the voice coil 4 is electrically connected by soldering between a terminal (not shown) fixed to the frame 7 and a lead wire of the coil 4 from the terminal. A current can be supplied. The tinsel wire may be electrically connected to the terminal by providing a metal eyelet on the speaker diaphragm 2. A dust cap 6 is attached to the center side of the speaker diaphragm 2 with an adhesive. The dust cap 6 closes the magnetic gap 9 of the magnetic circuit 10 and the end of the coil bobbin of the voice coil 4 so that dust such as iron powder does not enter from the front side.

  The magnetic circuit 10 of the present embodiment is an outer magnet type magnetic circuit including a plate 11, a magnet 12 coupled to the lower surface of the plate 11, and a pole 15. The pole 15 includes an under plate portion 13 to which the lower surface of the magnet 12 is connected and a columnar portion 14 that passes through the circular hole of the magnet 12 and forms a magnetic gap 9 between the plate 11. The pole 15 is a stepped pole having an inner diameter end defining a groove portion 16 that prevents the bobbin of the voice coil 4 from contacting the bottom between the underplate portion 13 and the columnar portion 14. The dimension is larger than the inner diameter dimension of the plate 11 and is substantially equal to the inner diameter dimension of the inner diameter end of the under plate portion 13 of the pole 15. The magnetic circuit 10 forms a high magnetic flux density DC magnetic field in an annular magnetic gap 9 defined between the columnar portion 14 of the pole 15 and the inner peripheral end of the plate 11. Therefore, when a voice current is supplied to the coil of the voice coil 4 disposed in the magnetic gap 9, a driving force acts on the voice coil 4 to vibrate the speaker diaphragm 2. Therefore, the electrodynamic speaker 1 can convert an audio signal current into a sound wave.

  The upper surface of the plate 11 of the magnetic circuit 10 is connected to the magnetic circuit fixing portion of the resin frame 7. The frame 7 is a speaker frame formed from ABS alloy resin. The frame 7 includes an annular portion formed on the outer peripheral side of the front surface, a magnetic circuit fixing portion formed on the inner peripheral side of the back surface with respect to the annular portion, and a connecting portion that connects the annular portion and the magnetic circuit fixing portion. This is a substantially basket-shaped speaker frame. The annular portion of the frame 7 is formed with an attachment portion (not shown) that defines an attachment hole (not shown) attached to the vehicle body of the vehicle. The annular portion of the frame 7 has an edge fixing portion that fixes the outer peripheral end side of the edge 3 to which the speaker diaphragm 2 is connected. The magnetic circuit fixing portion to which the magnetic circuit of the frame 7 is fixed has a center hole that communicates with the magnetic gap 9 of the magnetic circuit and a damper fixing portion that fixes the outer peripheral portion of the damper 5. The edge fixing portion and the damper fixing portion are annular plane portions that bond the edge and the damper, respectively. The connecting portions are columnar portions having a U-shaped cross section for connecting the magnetic circuit fixing portion and the annular portion, and a total of six connecting portions are provided at substantially intervals in the circumferential direction around the center point O. Since the annular portion is disposed on the front side of the frame 7 when viewed from the magnetic circuit fixing portion, the connecting portion extends from the magnetic circuit fixing portion to the annular portion on the front side.

  The magnet 12 constituting the magnetic circuit 10 is a resin magnet including samarium iron nitride (Sm—Fe—N) magnetic powder and a nylon resin including the magnetic powder to form a base. The magnetic powder of the magnet 12 may be a magnetic powder of another magnet such as a ferrite magnet, an alnico magnet, a samarium-cobalt magnet, and the resin as a binder of the magnet 12 is polyamide resin, polystyrene resin, polyethylene Other synthetic resins such as a resin may be used. The magnet 12 can increase the magnetic flux density in the magnetic gap 9 of the magnetic circuit 10 by increasing the ratio of the magnetic powder and decreasing the ratio of the resin within a range that can be molded at the time of manufacture. For example, the ratio of the magnetic powder and the resin of the magnet 12 is preferably about 30 to 60% magnetic powder and about 70 to 40% resin.

  The outer diameter of the base of the magnet 12 is larger than the outer diameter of the underplate portion 13 of the plate 11 and the pole 15, and the outer peripheral end 12 c of the base is on the outer peripheral side of the plate 11 and the underplate 13. Protruding. The magnet 12 is magnetized so that the first plane 12a on the upper surface side of the substrate and the second plane 12b on the lower surface side of the substrate have different magnetic polarities, and the radial direction and thickness of the annular substrate. It has magnetism with different orientation magnetization depending on the part in the direction and the predetermined range. Specifically, the magnet 12 of the magnetic circuit 10 is molded in advance so that the orientation of the magnetic powder is in a predetermined range within a specific range, and an easy magnetization direction is provided in the resin flow direction at the time of molding. The orientation can be adjusted as follows. The magnet 12 can obtain a predetermined orientation magnetization through a step of magnetizing with a magnetizer after assembling the plate 11, the magnet 12 and the pole 15 using an adhesive and a manufacturing jig. Of course, the magnet 12 is molded and magnetized in advance so that the orientation of the magnetic powder is in a predetermined range within a specific range, and the plate 11, the magnet 12 and the pole 15 are assembled using an adhesive and a manufacturing jig. May be.

  In the magnetic circuit 10 of this embodiment, as shown in FIG. 2, in the first range 21 in the radial direction of the base of the magnet 12, orientation magnetization is performed in the orthogonal direction orthogonal to the first plane 12a and the second plane 12b. Is done. On the other hand, the second range 22a in the radial direction of the base of the magnet 12 is provided in a predetermined range including the outer peripheral end 12c of the base, and the second range 22b is a predetermined including the inner peripheral end 12d of the base. Provided in the range. The direction in which the magnetic powder is oriented and magnetized is indicated by a vertically upward arrow in the first range 21, and is indicated by an upward arrow curved in a direction different from the orthogonal direction in the second range 22a or 22b. .

  For example, the second range 22 a on the outer peripheral side is a range in which the outer peripheral end 12 c of the base body of the magnet 12 protrudes more outward than the plate 11 and the under plate part 13. As shown in the enlarged view of FIG. 2B, the second range 22a on the outer peripheral side is a direction angle in the magnetization direction in the range near the center of the thickness of the substrate far from 12b on the first plane 2a and the second plane. The orientation magnetization is performed so that the absolute value of the difference θ is small. Therefore, in the second range 22a, the passing magnetic field lines swell toward the outer periphery side, unlike the orthogonal direction. However, since the second range 22 a is provided in a range that includes the outer peripheral end 12 c of the base body and protrudes to the outer peripheral side from the plate 11 and the under plate portion 13, the passing magnetic field lines pass through the magnetic path of the magnetic circuit 10. It will pass through and will not leak into the external space. As a result, in the magnetic circuit 10, the magnetic flux density in the magnetic gap 9 can be increased.

  In the second range of the magnet, it is preferable that the orientation and magnetization direction is restricted to a direction intersecting with the orthogonal direction within a range of ± 45 degrees. Preferably, in the range close to the first plane 12a and the second plane 12b, the absolute value of the direction angle difference θ in the magnetization direction is large in the range of 10 to 45 degrees, and from 12b to the first plane 2a and the second plane. It is preferable that the orientation magnetization is performed so that the absolute value of the direction angle difference θ in the magnetization direction gradually decreases toward the center of the thickness of the distant base, and becomes 0 degrees near the center of the thickness. Most preferably, in the range close to the first plane 12a and the second plane 12b, the absolute value of the direction angle difference θ in the magnetization direction is as large as about 30 degrees within the range of 10 to 45 degrees. The magnetic flux density in the magnetic air gap 9 of the circuit 10 can be maximized.

  Further, in the second range 22b on the inner peripheral side, the absolute value of the direction angle difference θ in the magnetization direction is substantially constant regardless of the distance from the first plane 12a or the second plane 12b. Unlike the orthogonal direction, swells outward. However, the second range 22b is such that the inner diameter dimension of the magnet 12 is larger than the inner diameter dimension of the plate 11 and is substantially equal to the inner diameter dimension of the inner diameter end of the underplate portion 13 of the pole 15. Since it is provided in the range including the inner peripheral side end 12d, the magnetic field lines that easily leak into the space between the adjacent inner peripheral side end 12d and the plate 11 pass through the magnetic path of the magnetic circuit 10. The magnetic flux density in the gap 9 can be increased. As a result, the symmetry of the magnetic flux density distribution is improved between the upper side and the lower side of the magnetic gap 9, so that the symmetry of the driving force that the voice coil 4 receives from the magnetic circuit 10 is improved. Then, there is an advantage that even-order nonlinear distortion is reduced.

  In the magnetic circuit 10 of the electrodynamic speaker 1, the shape dimensions of the plate 11 and the pole 15 are not limited to those in the present embodiment. In the magnetic circuit 10, the pole 15 is a stepped pole having an inner diameter end that defines a groove portion 16 that prevents the bobbin of the voice coil 4 from contacting the bottom between the underplate portion 13 and the columnar portion 14. However, the pole 15 may be a pole in which the columnar portion 14 is provided in the center of the planar under plate. The electrodynamic speaker 1 of the present embodiment is a vehicle electrodynamic speaker having a circular speaker diaphragm 2, but an oval having an outer diameter that is oval or suitable for the rectangular speaker diaphragm 2. Or the speaker diaphragm 2 which has a rectangular annular part may be sufficient.

The magnet 12 of the magnetic circuit 10 is a resin magnet including another magnetic powder and a resin that includes the magnetic powder to form the base, and a plate corresponding to the first range 21 in the radial direction of the base. 11 and the outer peripheral end 12c and the inner peripheral end corresponding to the second range 22 (22a and 22b) in the radial direction of the base in the range sandwiched by the underplate portion 14 of the pole 15 In the range including the portion 12d, the present invention is not limited to the case of this embodiment as long as it is bent and oriented and magnetized in a direction different from the orthogonal direction. If the magnet 12 can be bent in a direction different from the orthogonal direction by orientation magnetization, the first range 21 and the second range 22 can be increased so that the magnetic flux density distribution in the magnetic gap 9 can be increased. You may change a ratio mutually. Also, the angle θ corresponding to the direction of orientation magnetization is preferably regulated in the second range 22 of the magnet 12 in a direction that intersects the orthogonal direction within a range of ± 45 degrees.
The speaker diaphragm 2 which has may be sufficient.

  The magnet 12 of the magnetic circuit 10 may be composed of a plurality of magnets. That is, the magnet 12 includes a magnet that is oriented and magnetized in the orthogonal direction corresponding to the portion corresponding to the first range 21 of the base, and the orthogonal that corresponds to the portion corresponding to the second range 22 (22a and 22b) of the base. A magnet that is curved in a direction different from the direction and oriented and magnetized may be divided and connected. Alternatively, the magnet 12 may be a resin magnet that molds a portion corresponding to the first range 21 and a portion corresponding to the second range 22 of the base in two colors.

  The electrodynamic speaker of the present invention is not only a magnetic circuit and electrodynamic speaker that are desired to increase the magnetic flux density and increase the efficiency of sound reproduction even when resin magnets are used, but also images of displays, etc. -It is applicable also to game machines, a slot machine, etc. which have the cabinet which incorporates the speaker incorporated in an audio equipment, or the speaker which reproduces | regenerates an audio | voice.

DESCRIPTION OF SYMBOLS 1 Electrodynamic type speaker 2 Speaker diaphragm 3 Edge 4 Voice coil 5 Damper 6 Dust cap 7 Frame 9 Magnetic air gap 10 Magnetic circuit 11 Plate 12 Magnet 13 Underplate part 14 Columnar part 15 Pole 21 1st range 22 and 22a of a base | substrate 22b Second range of substrate

Claims (7)

A magnet having an annular base defined by a first plane and a second plane parallel to each other; an annular plate having a lower surface coupled to the first plane; an underplate portion coupled to the second plane; A magnetic circuit for an electrodynamic loudspeaker comprising: a pole including a columnar portion that passes through a circular hole of the magnet and forms a magnetic gap with the plate;
The magnet is magnetized so that the side of the first plane and the side of the second plane have different magnetic polarities, and in the first range in the radial direction of the base, the first plane and the magnet Oriented and magnetized in an orthogonal direction orthogonal to the second plane, and oriented and magnetized in a direction different from the orthogonal direction in the second range in the radial direction different from the first range of the substrate.
Magnetic circuit. The second range of the magnet is provided in a predetermined range including an outer peripheral end of the base and / or an inner peripheral end of the base.
The magnetic circuit according to claim 1. The magnet is a resin magnet that includes magnetic powder and a resin that includes the magnetic powder to form the substrate.
The magnetic circuit according to claim 1. The outer diameter of the base of the magnet is larger than the outer diameter of the underplate portion of the plate and the pole, and the second range of the magnet includes the outer peripheral side end of the base and the plate and Provided in a range protruding to the outer peripheral side from the under plate part,
The magnetic circuit according to claim 1. The under plate portion of the pole has an inner diameter end defining a groove portion with the columnar portion, the inner diameter size of the magnet is larger than the inner diameter size of the plate, and the under plate of the pole Approximately equal to the inner diameter dimension of the inner diameter end of the portion, and the second range of the magnet is provided in a predetermined range including the inner peripheral end of the base of the magnet.
The magnetic circuit according to claim 1. In the second range of the magnet, the magnetization direction to be oriented and magnetized is regulated in a direction intersecting with the orthogonal direction within a range of ± 45 degrees, and in a range close to the first plane and the second plane. Orientation and magnetization are performed so that the absolute value of the difference in the direction angle of the magnetization direction is large, and the direction angle of the magnetization direction is in a range near the center of the thickness of the substrate far from the first plane and the second plane. Oriented and magnetized so that the absolute value of the difference is small,
The magnetic circuit according to claim 1. The magnetic circuit according to any one of claims 1 to 6,
A frame having a magnetic circuit fixing portion for fixing the magnetic circuit;
A voice coil having a coil disposed in a magnetic gap of the magnetic circuit;
A speaker diaphragm connected to the voice coil on the center side;
An edge connected to an outer peripheral end side of the speaker diaphragm and an edge fixing portion of the frame;
A damper connected to the damper fixing portion of the voice coil and the frame;
An electrodynamic type speaker.

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