JP2008211675A - Magnetic circuit and electrokinetic type speaker using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic circuit in which if a conductive member is provided in a magnetic crevice, the radiation sound caused by its vibration seldom affects a reproduction sound quality, and to provide an electrokinetic type speaker using the same. <P>SOLUTION: The magnetic circuit includes: a magnet; a plurality of magnetic path constituent members forming a magnetic path having the annular magnetic crevice together with the magnet; a conductive member having a conductive planar part and a conductive cylindrical part extending from an outer peripheral side end of the conductive planar part to a substantially right-angled direction; and a vibration damping member for suppressing a vibration in the conductive planar part of the conductive member. The conductive cylindrical part of the conductive member is fixed to the magnetic path constituent member so as to cover an inner peripheral side of the magnetic crevice, and the vibration damping member is fixed to one face of the conductive planar part of the conductive member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic circuit used for an electrodynamic speaker or the like, and more particularly to a magnetic circuit including a conductive member such as a conductive ring or a copper cap in a magnetic gap, and an electrodynamic speaker using the magnetic circuit.

  In an electrodynamic speaker that reproduces sound, a magnetic circuit composed of a magnet and a plurality of magnetic path constituent members forming a magnetic path such as a yoke, a plate, and a pole is used. An annular magnetic gap is formed in which the coil is placed. When a voice current is supplied to the voice coil, a driving force is generated by a DC magnetic field in the magnetic gap, and the vibration system including the diaphragm and the voice coil vibrates, and the vibration is converted into a sound wave by the diaphragm, and as a result Sound is played from the electrodynamic speaker. Various magnetic circuits such as an inner magnet type magnetic circuit, an outer magnet type magnetic circuit, and a repulsive type magnetic circuit are known as magnetic circuits of electrodynamic speakers.

  In the annular magnetic gap of the magnetic circuit of the electrodynamic speaker, a conductive member formed from a conductive metal, specifically, a non-magnetic alloy containing copper or aluminum is formed in a cap shape or a ring. In some cases, it is arranged in a shape. Since these conductive members generate an induced current that tries to cancel the AC magnetic flux generated in the voice coil, the conductive member consequently reduces the inductance component of the electrical impedance of the voice coil. Works. Therefore, the provision of the conductive member has advantages such as increasing the reproduction sound pressure level in the high sound range of the electrodynamic speaker or improving the distortion characteristics. In many cases, the conductive member is fixed to the magnetic path component of the magnetic circuit with an adhesive.

  Conventionally, for example, there are a magnetic circuit in which the shape of a conductive member disposed in the vicinity of the magnetic gap or the magnetic gap of the magnetic circuit is devised, and an electrodynamic speaker (Patent Document 1). Further, for example, at least one of the top plate and the ball beads is formed by a magnetic pole plate made of two ferromagnetic materials and an annular plate made of a good conductor sandwiched between the two magnetic pole plates and facing the voice coil. There are some speakers (Patent Document 2). Conventionally, there is a speaker using a vibration-proof aluminum alloy as a material for a ring-shaped conductive member (Patent Document 3).

Japanese Patent Laid-Open No. 48-68219 JP-A 61-137396 Japanese Patent No. 2586574

  In addition to the above advantages, a speaker having a conventional copper cap may reproduce sound with a unique tone of “copper cap”. In other words, although the conductive member is fixed to the magnetic path constituent member of the magnetic circuit with an adhesive, the radiated sound generated when the conductive member vibrates due to the vibration generated in the magnetic circuit, and the conductive property. Radiating sound generated by vibration of the conductive member due to the induced current flowing through the member is radiated. As a result of verification by the inventor's experiment, these vibration radiated sounds radiated by the conductive member fixed to the magnetic circuit tend to increase in the high sound range even though the reproduction sound pressure level is low, which affects the reproduction sound quality. There is a known problem.

  The present invention has been made in order to solve the above-described problems of the prior art. The purpose of the present invention is to have an effect on the reproduced sound quality due to the radiated sound caused by the vibration even if the conductive member is provided in the magnetic gap. An object of the present invention is to provide a small number of magnetic circuits and an electrodynamic speaker using the same.

  The magnetic circuit of the present invention includes a magnet, a plurality of magnetic path constituent members that form a magnetic path having an annular magnetic gap together with the magnet, a conductive plane portion, and an outer peripheral side end portion of the conductive plane portion in a substantially perpendicular direction. A conductive member having a conductive cylindrical portion that is extended, and a damping member that suppresses vibration of the conductive flat portion of the conductive member, and the conductive cylindrical portion of the conductive member is within the magnetic gap. The magnetic path constituting member is fixed so as to cover the peripheral side, and the vibration damping member is fixed to one surface of the conductive flat surface portion of the conductive member.

  Preferably, in the magnetic circuit of the present invention, the damping member is a center plate that also serves as the magnetic path constituent member and forms the magnetic path and the inner peripheral side of the magnetic gap, and the plurality of magnetic path constituent members are magnetic gaps. Including a yoke forming the outer peripheral side of the conductive plate, and fixing one surface of the conductive flat portion of the conductive member to the bottom surface of the center plate, and fixing the conductive cylindrical portion of the conductive member to the side surface of the center plate One surface of the magnet is fixed to the other surface of the conductive flat portion of the member, and the inner bottom surface portion of the yoke is fixed to the other surface of the magnet.

  Further preferably, the magnetic circuit of the present invention further includes a repulsive magnet magnetized in a direction opposite to the magnetizing direction of the magnet, and the bottom surface of the repulsive magnet is fixed to the upper surface of the center plate.

  Preferably, in the magnetic circuit of the present invention, the damping member is a center plate that also serves as the magnetic path constituent member to form the magnetic path and the inner peripheral side of the magnetic gap, and the plurality of magnetic path constituent members include: Including a pole and a top plate that forms the outer peripheral side of the magnetic gap, wherein one surface of the conductive flat portion of the conductive member is fixed to the bottom surface of the center plate, and the conductive cylinder of the conductive member is attached to the side surface of the center plate The convex portion of the pole is fixed to the other surface of the conductive flat portion of the conductive member, the bottom surface of the magnet is fixed to the under plate of the pole, and the top plate is fixed to the upper surface of the magnet.

  Preferably, in the magnetic circuit of the present invention, the vibration damping member fixed to one surface of the conductive flat portion of the conductive member includes a flat plate elastic body and a non-magnetic and fixed vibrationally fixed to the elastic body. A non-conductive mass body, wherein the plurality of magnetic path constituent members includes a center plate that forms the inner peripheral side of the magnetic gap, and a yoke that forms the outer peripheral side of the magnetic gap, and the upper surface of the center plate The other side of the conductive flat portion of the conductive member is fixed to the center plate, the conductive cylindrical portion of the conductive member is fixed to the side surface of the center plate, the upper surface of the magnet is fixed to the bottom surface of the center plate, and the bottom surface of the magnet is fixed to the bottom surface of the magnet. The inner bottom surface of the yoke is fixed.

  Preferably, in the magnetic circuit of the present invention, the vibration damping member fixed to one surface of the conductive flat portion of the conductive member includes a flat plate elastic body and a non-magnetic and fixed vibrationally fixed to the elastic body. A non-conductive mass, and a plurality of magnetic path constituent members, a pole that forms the inner peripheral side of the magnetic gap, and a top plate that forms the outer peripheral side of the magnetic gap, and the convex shape of the pole Fixing the other surface of the conductive plane portion of the conductive member to the portion, and fixing the conductive cylindrical portion of the conductive member to the side surface of the convex portion of the pole, and fixing the bottom surface of the magnet to the under plate of the pole; Secure the top plate to the top of the magnet.

  The electrodynamic speaker according to the present invention includes a diaphragm, a voice coil having a bobbin wound around the coil and coupled to the diaphragm, an edge supporting the outer peripheral end of the diaphragm, and a bobbin. A damper that supports the inner peripheral end side of the diaphragm, a frame that fixes the edge and the outer peripheral end side of the damper, respectively, and a magnetic circuit that is connected to the frame and arranges a coil in the magnetic gap.

  The operation of the present invention will be described below.

  The magnetic circuit of the present invention includes a magnet, a plurality of magnetic path constituting members, a conductive member, and a damping member that suppresses vibration of the conductive flat surface portion, and these are fixed by an adhesive. Specifically, the magnet is a permanent magnet including a ferromagnetic material such as a rare earth magnet, and the plurality of magnetic path constituent members are members formed of a metal such as iron, such as a yoke, plate, or pole, having high magnetic permeability. It is. A plurality of magnetic path constituent members form a magnetic path having an annular magnetic gap together with a magnet, and an inner magnet type magnetic circuit or an outer magnet type magnetic circuit depending on the magnet material, shape, and arrangement relationship with the magnetic gap. Further, when a repulsive magnet is further provided, one of the repulsive magnetic circuits is configured.

  The electrodynamic speaker of the present invention is configured using any of these magnetic circuits, and includes a diaphragm, a voice coil having a bobbin around which the coil is wound and connected to the diaphragm, and an outer periphery of the diaphragm An edge supporting the end side, a damper connected to the bobbin to support the inner peripheral end side of the diaphragm, and a frame for fixing the edge and the outer peripheral end side of the damper, respectively, and the magnetic circuit is connected to the frame Then, the coil is arranged in the magnetic gap.

  The conductive member has a conductive plane portion corresponding to an inner plane defined by the annular magnetic gap, and a conductive cylindrical portion extending in a substantially right angle direction from an outer peripheral side end of the conductive plane portion. That is, the conductive member has a disk-shaped conductive flat portion and a conductive cylindrical portion extending in a substantially right-angle direction from the outer peripheral side end portion, and is typically made of a copper alloy having a concave shape as a whole. It is a copper cap. In the magnetic circuit of the present invention, the conductive member is fixed to the magnetic path constituent member so that the conductive cylindrical portion covers the inner peripheral side of the magnetic gap. Since the conductive member has a conductive cylindrical part close to the voice coil located in the magnetic gap in addition to the disk-shaped conductive flat part, the alternating magnetic flux generated from the voice coil is easily crossed, and the electrodynamic speaker The effect of providing a conductive member such as increasing the reproduction sound pressure level in the high sound range or improving the distortion characteristic can be exhibited.

  On the other hand, in the magnetic circuit of the present invention, the damping member is fixed to one surface of the conductive flat portion of the conductive member. The damping member is a center plate that also serves as a magnetic path constituent member and forms the magnetic path and the inner peripheral side of the magnetic gap, or a flat elastic body and a non-magnetic material that is fixed to the elastic body so as to vibrate And a combination with a non-conductive mass body. The one surface of the conductive flat surface portion of the conductive member is a disk-shaped surface of either the concave side or the convex side of the concave shape. For example, when the concave side is one surface, the convex side is The other side.

  The vibration damping member emits vibration radiation sound emitted from the conductive member due to vibration generated in the magnetic circuit, and the conductive member vibrates due to the induced current flowing through the conductive member. Vibration vibration sound is suppressed. Specifically, when the center plate is fixed to one surface of the conductive flat portion of the conductive member, the amplitude of vibration of the conductive flat portion of the conductive member is limited, so that the vibration emission sound of the conductive member is reduced. To do. Alternatively, when a flat plate-like elastic body and a non-magnetic non-conductive mass body are fixed to one surface of the conductive flat portion of the conductive member, the vibration of the conductive flat portion of the conductive member As a result, the vibration radiation sound of the conductive member is reduced.

  Since the electrodynamic speaker of the present invention is configured using any one of these magnetic circuits, even if the conductive member is provided in the magnetic gap, the influence of the radiated sound due to the vibration on the reproduced sound quality is reduced. be able to. Therefore, by providing a conductive member, it is possible to increase the reproduced sound pressure level in the high sound range of the electrodynamic speaker, or to improve the distortion characteristics, and to suppress the vibration radiation sound of the conductive member. Thus, the reproduction sound quality can be improved.

  Providing a conductive member to increase the reproduced sound pressure level in the high sound range of the electrodynamic speaker, or improving the distortion characteristics, etc. It is possible to provide a magnetic circuit in which the radiated sound due to the vibration has little influence on the reproduction sound quality, and an electrodynamic speaker using the magnetic circuit.

  The magnetic circuit of the present invention aims to provide a magnetic circuit in which even if a conductive member is provided in a magnetic gap, the magnetic sound emitted from the vibration has little influence on the reproduced sound quality. A conductive member having a plurality of magnetic path constituent members forming a magnetic path having a conductive plane portion, and a conductive cylindrical portion extending in a substantially perpendicular direction from an outer peripheral side end of the conductive plane portion; A damping member that suppresses vibration of the conductive flat portion of the conductive member, and the conductive cylindrical portion of the conductive member is fixed to the magnetic path component member so as to cover the inner peripheral side of the magnetic gap, This was realized by fixing the member to one surface of the conductive flat portion of the conductive member.

  Hereinafter, although a magnetodynamic circuit and an electrodynamic speaker according to preferred embodiments of the present invention will be described, 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. 1A is a cross-sectional view of the electrodynamic speaker 1, and FIG. 1B is a cross-sectional view illustrating an internal magnet type magnetic circuit 10 constituting the electrodynamic speaker 1. The electrodynamic speaker 1 is a cone type speaker including a cone type diaphragm 2, a voice coil 3, and an inner magnet type magnetic circuit 10. A part of the structure of the electrodynamic speaker 1 that is not necessary for the description, an internal structure, and the like are omitted.

  The cone-type diaphragm 2 of the electrodynamic speaker 1 has an edge 4 bonded to the outer peripheral end thereof, and a bobbin 3b of the voice coil 3 bonded to the inner peripheral end thereof. The cone-type diaphragm 2 is typically used as a diaphragm for a speaker, regardless of the material or the shape of the cone curve. The voice coil 3 is formed of a coil 3a to which a sound current is supplied and a bobbin 3b around which the coil 3a is wound. The lead wire from the coil 3 a is soldered to the tinsel wire 8 and soldered to the terminal 9 fixed to the frame 6. The dust cap 7 is connected so as to close the inner peripheral side of the cone-shaped diaphragm 2 and is fixed with an adhesive.

  The edge 4 is a roll edge having flexibility, and its outer peripheral side is fixed to a fixing portion of a frame 6 described later. The damper 5 is a corrugation damper having flexibility, and supports the inner peripheral end side of the cone-type diaphragm 2 by being connected to the other end side where the coil 3a of the bobbin 3b is not wound. The outer peripheral end side of the damper 5 is fixed to a fixing portion of the frame 6. The frame 6 is formed in a basket shape, and connects the inner magnetic circuit 10 to the bottom.

  Accordingly, the speaker vibration system including the cone-shaped diaphragm 2, the voice coil 3, the edge 4, the damper 5, and the dust cap 7 is supported so as to be able to vibrate with respect to the frame 6 and the inner magnet type magnetic circuit 10. The coil 3a is disposed in a magnetic gap 15 of the inner magnet type magnetic circuit 10 to be described later. When an audio current is supplied to the coil 3a through the terminal 9 and the tinsel wire 8, a driving force is generated by the DC magnetic field in the magnetic gap 15, and the vibration in the cone-type diaphragm 2 is converted into a sound wave. Sound is reproduced from the electrodynamic speaker 1.

  The inner magnet type magnetic circuit 10 includes a magnet 11, a center plate 12, a yoke 13, and a copper cap 16, which are fixed with an adhesive. The copper cap 16 is formed by press-molding a copper plate having a thickness of 0.2 to 0.3 mm, and has a disk-like conductive flat surface portion 16a and a conductive cylindrical shape extending in a substantially right angle direction from the outer peripheral side end portion. It has the part 16b and is a concave shape as a whole. In the internal magnetic circuit 10, the concave side of the conductive flat portion 16 a of the copper cap 16 is fixed to the bottom surface of the center plate 12, and the conductive cylindrical portion 16 b of the copper cap 16 is fixed to the side surface of the center plate 12. The upper surface of the magnet 11 is fixed to the convex side of the conductive flat portion 16 a, and the inner bottom surface portion of the yoke 13 is fixed to the bottom surface of the magnet 11.

  In the inner magnet type magnetic circuit 10 including the magnetized magnet 11, a magnetic path through which the DC magnetic flux generated by the magnet 11 passes is formed, and an annular magnetic gap 15 is formed between the center plate 12 and the yoke 13. Is done. The center plate 12 forms the inner peripheral side of the magnetic air gap 15, and the yoke 13 forms the outer peripheral side of the magnetic air gap 15. As described above, in the magnetic gap 15, the conductive cylindrical portion 16 b of the copper cap 16 is fixed so as to cover the inner peripheral side of the magnetic gap 15, that is, the side surface of the center plate 12.

  As a result, in the electrodynamic speaker 1 provided with the inner magnet type magnetic circuit 10, the copper cap 16 disposed in the magnetic gap 15 is close to the voice coil 3, so that the alternating magnetic flux generated from the voice coil 3 is applied to the copper cap 16. It becomes easy to cross. In the electrodynamic speaker 1, the electrical impedance characteristic does not increase in the high sound range, the reproduction sound pressure level in the high sound range of the electrodynamic speaker 1 increases, and the distortion characteristic is improved. Further, in the inner magnet type magnetic circuit 10, the center plate 12 is fixed to the concave side of the conductive flat portion 16 a of the copper cap 16, so that the center plate 12 is connected to the magnetic path of the inner magnet type magnetic circuit 10 as described later. In addition, the copper cap 16 functions as a vibration damping member that suppresses vibration radiation sound emitted by vibration.

  FIG. 2 is a diagram for explaining another magnetic circuit constituting an electrodynamic speaker according to another preferred embodiment of the present invention. FIG. 2A is a cross-sectional view of the repulsive magnetic circuit 17, and FIG. 2B is a cross-sectional view illustrating the external magnetic type magnetic circuit 20. The inner magnet type magnetic circuit 10, the repulsive type magnetic circuit 17, and the outer magnet type magnetic circuit 20 are the same in that they each have the same shape center plate 12 and the same shape copper cap 16. The repulsive-type magnetic circuit 17 and the external-magnetic-type magnetic circuit 20 are connected to the same speaker vibration system and frame that constitute the electrodynamic speaker 1, respectively, so that another preferred embodiment of the present invention (not shown) is provided. Constitutes an electrodynamic speaker. In addition, since the structure of these electrodynamic type speakers is common, description is abbreviate | omitted.

  The repulsive magnetic circuit 17 is configured by further adding a repulsive magnet 18 to the inner magnet magnetic circuit 10 including the copper cap 16 described above. That is, a repulsion magnet 18 magnetized in the direction opposite to the magnetization direction of the magnet 11 is further provided, and the bottom surface of the repulsion magnet 18 is fixed to the upper surface of the center plate 12. In the repulsive magnetic circuit 17, an annular magnetic gap 19 is formed between the center plate 12 and the yoke 13.

  Therefore, a stronger DC magnetic field is generated in the magnetic gap 19 of the repulsive magnetic circuit 17. The electrodynamic speaker provided with the repulsive magnetic circuit 17 does not increase its electrical impedance characteristics in the high sound range and improves the distortion characteristics, like the electrodynamic speaker 1 described above. In addition, the playback sound pressure level of the electrodynamic speaker further increases as a whole. Although the description common to the above-described inner magnet type magnetic circuit 10 is omitted, the center plate 12 forms a magnetic path also in the repulsive type magnetic circuit 17 and the vibration that the copper cap 16 vibrates and radiates. It functions as a damping member that suppresses radiated sound.

  On the other hand, the outer magnet type magnetic circuit 20 includes a magnet 21, a center plate 12, a pole 23, a top plate 24, and a copper cap 16, which are fixed with an adhesive. In the outer magnet type magnetic circuit 20, the concave side of the conductive flat portion 16 a of the copper cap 16 is fixed to the bottom surface of the center plate 12, and the conductive cylindrical portion 16 b of the copper cap 16 is fixed to the side surface of the center plate 12. The convex portion of the pole 23 is fixed to the convex side of the conductive flat portion 16 a, the bottom surface of the magnet 21 is fixed to the under plate of the pole 23, and the top plate 24 is fixed to the upper surface of the magnet 21.

  In the outer magnet type magnetic circuit 20 including the magnetized magnet 21, a magnetic path through which the DC magnetic flux generated by the magnet 21 passes is formed, and an annular magnetic gap 25 is formed between the center plate 12 and the top plate 24. It is formed. The center plate 12 forms the inner peripheral side of the magnetic air gap 25, and the top plate 24 forms the outer peripheral side of the magnetic air gap 25. As described above, in the magnetic gap 25 of the outer magnet type magnetic circuit 20, the conductive cylindrical portion 16 b of the copper cap 16 is fixed so as to cover the inner peripheral side of the magnetic gap 25, that is, the side surface of the center plate 12.

  As a result, even in an electrodynamic speaker equipped with the external magnetic circuit 20, the copper cap 16 disposed in the magnetic gap 25 is close to the voice coil, so that the alternating magnetic flux generated from the voice coil easily crosses the copper cap 16. Therefore, the electrical impedance characteristic does not increase in the high sound range, the reproduction sound pressure level in the high sound range of the electrodynamic speaker increases, and the distortion characteristic is improved. In the outer magnet type magnetic circuit 20, the center plate 12 is fixed to the concave side of the conductive flat portion 16 a of the copper cap 16, so that the center plate 12 forms a magnetic path of the outer magnet type magnetic circuit 20, and The copper cap 16 functions as a vibration damping member that suppresses vibration radiation sound radiated by vibration.

  FIG. 3 is a diagram for explaining another magnetic circuit constituting an electrodynamic speaker according to another preferred embodiment of the present invention. FIG. 3A is a sectional view of the inner magnet type magnetic circuit 30, and FIG. 3B is a sectional view for explaining the outer magnet type magnetic circuit 40. The inner magnet type magnetic circuit 30 and the outer magnet type magnetic circuit 40 are common in that they each have the same shape of the copper cap 16, the same shape of the elastic body 37, and the same shape of the mass body 38. . The inner magnet type magnetic circuit 30 and the outer magnet type magnetic circuit 40 are connected to the same speaker vibration system and frame that constitute the above-described electrodynamic speaker 1, thereby connecting the electrodynamic of the present invention (not shown). Construct a type speaker. Since the structure and the like of these electrodynamic speakers are common, the description is omitted.

  The inner magnet type magnetic circuit 30 includes the magnet 11, the center plate 12, the yoke 13, the copper cap 16, the flat elastic body 37, and a nonmagnetic and nonconductive mass. The body 38 is configured. The magnet 11, the center plate 12, the yoke 13, and the copper cap 16 are fixed with an adhesive. The copper cap 16 in the inner magnet type magnetic circuit 30 is used upside down in the case of the inner magnet type magnetic circuit 10 described above. That is, in the internal magnetic circuit 30, the concave side of the conductive flat portion 16a of the copper cap 16 is fixed to the upper surface of the center plate 12, and the conductive cylindrical portion 16b of the copper cap 16 is fixed to the side surface of the center plate 32. The upper surface of the magnet 11 is fixed to the bottom surface of the plate 12, and the inner bottom surface portion of the yoke 13 is fixed to the bottom surface of the magnet 11.

  The flat elastic body 37 is fixed to the convex side of the conductive flat portion 16a of the copper cap 16, and the non-magnetic and non-conductive mass body 38 is fixed to the elastic body 37 so as to vibrate. Specifically, the flat elastic body 37 is formed by, for example, foaming foam made of polyethylene, polypropylene, polyurethane, rubber, etc. having a sponge-like porous body into a disk shape, and has elasticity. And can be deformed in the thickness direction. Further, the non-magnetic and non-conductive mass body 38 is formed by, for example, molding rubber, resin, or the like having a high density and hardness into a disk shape along the shape of the elastic body 37. The copper cap 16 and the elastic body 37 are fixed with an adhesive, and the mass body 38 is fixed with an adhesive so as to cover the elastic body 37.

  In the inner magnet type magnetic circuit 30 including the magnetized magnet 11, a magnetic path through which the DC magnetic flux generated by the magnet 11 passes is formed, and an annular magnetic gap 35 is formed between the center plate 12 and the yoke 13. Is done. The center plate 12 forms the inner peripheral side of the magnetic air gap 35, and the yoke 13 forms the outer peripheral side of the magnetic air gap 35. As described above, in the magnetic gap 35 of the inner magnet type magnetic circuit 30, the conductive cylindrical portion 16 b of the copper cap 16 is fixed so as to cover the inner peripheral side of the magnetic gap 35, that is, the side surface of the center plate 12.

  As a result, in the electrodynamic speaker provided with the internal magnetic circuit 30, the copper cap 16 disposed in the magnetic gap 35 is close to the voice coil, so that the alternating magnetic flux generated from the voice coil easily crosses the copper cap 16. Therefore, the electrical impedance characteristic does not increase in the high sound range, the reproduction sound pressure level in the high sound range of the electrodynamic speaker increases, and the distortion characteristic is improved. In the internal magnetic circuit 30, the flat elastic body 37 and the nonmagnetic and nonconductive mass body 38 are fixed to the convex side of the conductive flat portion 16a of the copper cap 16, so that the elastic body 37 and the mass As will be described later, the body 38 functions as a vibration damping member that suppresses vibration radiation sound radiated by the copper cap 16 oscillating.

  The outer magnet type magnetic circuit 40 includes the magnet 21, the pole 43, the top plate 24, the copper cap 16, the flat elastic body 37, and the non-magnetic and non-conductive mass body 38. Is composed of. The magnet 21, the pole 43, the top plate 24, and the copper cap 16 are fixed with an adhesive. In the outer magnet type magnetic circuit 40, the concave side of the conductive flat portion 16a of the copper cap 16 is fixed to the convex portion of the pole 43, and the conductive cylindrical portion 16b of the copper cap 16 is fixed to the side surface of the convex portion of the pole 43. The bottom surface of the magnet 21 is fixed to the under plate of the pole 43, and the top plate 24 is fixed to the upper surface of the magnet 21.

  The flat elastic body 37 of the outer magnet type magnetic circuit 40 is fixed to the convex side of the conductive flat portion 16 a of the copper cap 16, as in the inner magnet type magnetic circuit 30, and is a nonmagnetic and nonconductive mass body 38. Is fixed to the elastic body 37 so as to vibrate.

  In the outer magnet type magnetic circuit 40 including the magnetized magnet 21, a magnetic path through which the DC magnetic flux generated by the magnet 21 passes is formed, and an annular magnetic gap 45 is formed between the pole 43 and the top plate 24. Is done. The convex portion of the pole 43 forms the inner peripheral side of the magnetic gap 45, and the top plate 24 forms the outer peripheral side of the magnetic gap 45. As described above, in the magnetic gap 45 of the outer magnet type magnetic circuit 40, the conductive cylindrical portion 16b of the copper cap 16 is fixed so as to cover the inner peripheral side of the magnetic gap 45, that is, the side surface of the convex portion of the pole 43. Is done.

  As a result, even in an electrodynamic speaker equipped with the outer magnet type magnetic circuit 40, since the copper cap 16 disposed in the magnetic gap 45 is close to the voice coil, the alternating magnetic flux generated from the voice coil easily crosses the copper cap 16. Therefore, the electrical impedance characteristic does not increase in the high sound range, the reproduction sound pressure level in the high sound range of the electrodynamic speaker increases, and the distortion characteristic is improved. Further, in the outer magnet type magnetic circuit 40, the flat elastic body 37 and the nonmagnetic and nonconductive mass body 38 are fixed to the convex side of the conductive flat portion 16a of the copper cap 16, so the elastic body 37 and the mass The body 38 functions as a damping member that suppresses vibration radiation sound emitted by the copper cap 16 oscillating.

  FIG. 4 is a diagram for explaining a magnetic circuit of a comparative example constituting a conventional electrodynamic speaker as a comparative example. 4 (c), 4 (d), 4 (e), and 4 (f) are cross-sectional views illustrating the internal magnet type magnetic circuits 50, 60, 70, and 80 of the comparative example, respectively. . The internal magnet type magnetic circuits 50, 60, 70, and 80 of the comparative example are common in that they do not include the damping member of the internal magnet type magnetic circuits 10 and 30 of the first and second embodiments. In addition, if the respective parts constituting the inner magnet type magnetic circuit of these comparative examples are the same as those constituting the inner magnet type magnetic circuits 10 and 30 of the first and second embodiments, the same numbers are assigned. The description is omitted. The internal magnet type magnetic circuit of these comparative examples constitutes the electrodynamic speaker of the comparative example (not shown) by connecting the same speaker vibration system and frame as those constituting the electrodynamic speaker 1 respectively. . In addition, since the structure of these electrodynamic speakers is common, the description is omitted.

  The inner magnet type magnetic circuit 50 of Comparative Example 1 includes a copper cap 16 and has an annular magnetic gap 55. That is, the internal magnet type magnetic circuit 50 of Comparative Example 1 is obtained by removing the plate-shaped elastic body 37 and the nonmagnetic and nonconductive mass body 38 from the internal magnet type magnetic circuit 30 of Example 2. This is a conventional example of an internal magnetic circuit including a general copper cap. In this inner magnet type magnetic circuit 50, the convex side of the conductive flat portion 16a of the copper cap 16 is exposed in a wide area.

  Further, the inner magnet type magnetic circuit 60 of Comparative Example 2 includes a copper cap 16 and a mass body 68 fixed to the convex side of the conductive flat portion 16 a of the copper cap 16, and has an annular magnetic gap 65. That is, the internal magnet type magnetic circuit 60 of Comparative Example 2 is a conventional example in which a simple mass body 68 is fixed to the convex side of the conductive flat portion 16a of the copper cap 16 of the internal magnet type magnetic circuit 50 of Comparative Example 1. is there. Here, the mass body 68 is a member having substantially the same mass as the mass body 38 in the second embodiment. In this inner magnet type magnetic circuit 60, the mass body 68 is exposed in a wide area instead of the convex side of the conductive flat portion 16 a of the copper cap 16.

  Further, in the inner magnet type magnetic circuit 70 of Comparative Example 3, instead of the center plate 12 and the copper cap 16, a center plate member in which three thin center plates 72 and four disc-shaped copper plates 76 are alternately stacked. And has an annular magnetic gap 75. That is, the inner magnet type magnetic circuit 70 is a conventional example in which the conductive member constituting the inner magnetic circuit 70 does not include a conductive cylindrical portion that covers the inner peripheral side of the magnetic gap 75. Also in this inner magnet type magnetic circuit 70, the uppermost laminated copper plate 76 is exposed in a wide area.

  Further, the inner magnet type magnetic circuit 80 of Comparative Example 4 does not include the copper cap 16 and has an annular magnetic gap 85. That is, the internal magnet type magnetic circuit 80 of the comparative example 4 is obtained by removing the copper cap 16 from the internal magnet type magnetic circuit 50 of the comparative example 1, and does not have a general copper cap. This is a conventional example.

  5 and 6 are graphs of frequency characteristics for comparing the inner magnet type magnetic circuits of Examples 1 and 2 with the inner magnet type magnetic circuits of Comparative Examples 1 to 4. FIG. Here, in order to measure the radiated sound caused by the vibration of the conductive member generated in the magnetic circuit having the conductive member in the magnetic gap, a vibration system including only the voice coil 3 is arranged in each magnetic gap (illustrated). No) Configure a magnetic circuit for measurement. Specifically, each voice coil 3 arranged in the measurement magnetic circuit is coated with an adhesive on the inner peripheral side of the bobbin 3b, and is independently bonded and fixed to each magnetic circuit. Also in electrodynamic speakers using the inner magnet type magnetic circuits of Examples 1 and 2 and the inner magnet type magnetic circuits of Comparative Examples 1 to 4, radiated sound as measured by these measuring magnetic circuits Is emitted, affecting the quality of reproduced sound.

  FIG. 5 is a graph of the sound pressure frequency characteristic at a distance of 1 m from the measurement magnetic circuit. FIG. 6 is a graph of electrical impedance characteristics of the measurement magnetic circuit. 5 and FIG. 6, (a) is Example 1, (b) is Example 2, (c) is Comparative Example 1, (d) is Comparative Example 2, (e) is Comparative Example 3, ( f) represents the case of Comparative Example 4. A sine wave input signal (1 W) of about 5 kHz to about 20 kHz is supplied to the voice coil of the measurement magnetic circuit. In these measurement magnetic circuits, when the voice coil 3 is included in the speaker vibration system when an electrodynamic speaker is configured, that is, when supported by the edge 4 and the damper 5 so as to be vibrated. However, if a current is supplied to the voice coil, a driving force is generated by a DC magnetic field in the magnetic gap. As a result, each measurement magnetic circuit oscillates and emits a sound wave, and a measurement result as shown in FIG. 5 is obtained. In addition, in the electrical impedance characteristics of FIG. 6, the influence of the conductive member included in each measurement magnetic circuit appears.

  First, (f) Comparative Example 1 including the copper cap 16 is compared with the Comparative Example 4 including no copper cap 16 as a reference. As shown in FIG. 6, in Comparative Example 1, the copper cap 16 acts and the inductance component of the electrical impedance is lower than that in Comparative Example 4. However, as shown in FIG. 5, the sound pressure level of the sound wave radiated from the measurement magnetic circuit of Comparative Example 1 is significantly increased near about 9 kHz and about 16 kHz as compared with Comparative Example 4. This is because in the inner magnet type magnetic circuit 50 of Comparative Example 1, the convex side of the conductive flat portion 16a of the copper cap 16 is exposed in a wide area and vibrates. That is, although the copper cap 16 is fixed to the magnetic circuit with an adhesive, the copper cap 16 vibrates due to vibration generated in the magnetic circuit, or vibrates due to induced current flowing through the copper cap 16, and radiated sound. Is radiating.

  Next, (c) Comparative Example 2 further including mass body 68 is compared with Comparative Example 1 including copper cap 16 as a reference. As shown in FIG. 6, in Comparative Example 1 and Comparative Example 2, the copper cap 16 acts to reduce the inductance component of the electrical impedance. However, as shown in FIG. 5, the sound pressure level of the sound wave radiated from the measurement magnetic circuit of the comparative example 2 is lower in the vicinity of about 9 kHz than the comparative example 1, but is not sufficiently reduced in the vicinity of about 16 kHz. This indicates that in the inner magnet type magnetic circuit 60 of the comparative example 2, the mass body 68 suppresses the vibration of the conductive flat portion 16a of the copper cap 16, but the mass body 68 alone does not sufficiently suppress the vibration. Yes.

  Similarly, on the basis of Comparative Example 1 including (c) the copper cap 16, (a) the embodiment including the copper cap 16 and the vibration suppression member (center plate 12) for suppressing the vibration of the copper cap 16. Contrast 1 In Comparative Example 1 and Example 1, the copper cap 16 acts to reduce the inductance component of the electrical impedance. Further, as shown in FIG. 5, the sound pressure level of the sound wave radiated from the measurement magnetic circuit of Example 1 is significantly reduced in the vicinity of about 9 kHz and in the vicinity of about 16 kHz as compared with Comparative Example 1. In the inner magnet type magnetic circuit 10 of the first embodiment, the center plate 12 has the concave side of the conductive flat portion 16a of the copper cap 16 fixed to the bottom surface thereof, and the conductive cylindrical portion 16b of the copper cap 16 fixed to the side surface thereof. This is because it functions as a vibration damping member that suppresses the vibration radiation sound of the copper cap 16. That is, the center plate 12 limits the amplitude of vibration of the conductive flat portion 16a of the copper cap 16, so that the vibration radiation sound of the copper cap 16 is reduced.

  Furthermore, (c) the damping member (the elastic body 37 and the mass body 38) that includes the copper cap 16 and suppresses the vibration of the copper cap 16 on the basis of the comparative example 1 including the copper cap 16 is provided. Contrast Example 2 provided. In Comparative Example 1 and Example 2, the copper cap 16 acts to reduce the inductance component of the electrical impedance. Further, as shown in FIG. 5, the sound pressure level of the sound wave radiated from the measurement magnetic circuit of Example 2 is remarkably lowered in the vicinity of about 9 kHz and in the vicinity of about 16 kHz as compared with Comparative Example 1. This is because, in the inner magnet type magnetic circuit 30 of the second embodiment, the flat elastic body 37 is fixed to the convex side of the conductive flat portion 16a of the copper cap 16, and the non-magnetic and non-conductive mass body 38 is This is because they are fixed to the elastic body 37 so as to vibrate, and these function as a damping member that suppresses the vibration radiation sound of the copper cap 16. In the vibration system formed by the flat elastic body 37 and the non-magnetic non-conductive mass body 38, the vibration of the copper cap 16 is absorbed, and as a result, the vibration radiation sound of the copper cap 16 is reduced.

  Finally, (c) on the basis of the comparative example 1 including the copper cap 16, (e) instead of the center plate 12 and the copper cap 16, three thin center plates 72 and four disc-shaped copper plates 76 are used. The comparative example 3 provided with the center plate member laminated | stacked alternately is contrasted. As shown in FIG. 6, in Comparative Example 1, the copper cap 16 acts to reduce the inductance component of the electrical impedance, whereas in Comparative Example 3, the electrical impedance is not sufficiently lowered, and the conductive cylinder It is shown that the laminated disk-shaped copper plate 76 that does not have the shape portion does not sufficiently function as a conductive member in the first place. Further, as shown in FIG. 5, the sound pressure level of the sound wave radiated from the measurement magnetic circuit of the comparative example 3 is relatively lower in the vicinity of about 16 kHz than in the comparative example 1, but is about 9 kHz. In, it is not decreasing, it is increasing. This indicates that in the inner magnet type magnetic circuit 70 of Comparative Example 3, the vibration of the uppermost laminated copper plate 76 is not suppressed.

  As described above, in the inner magnet type magnetic circuit 10 of the first embodiment and the inner magnet type magnetic circuit 30 of the second embodiment, vibration radiated sound radiated by the vibration of the copper cap 16 provided as the conductive member is suppressed. It can suppress, respectively, by providing a vibration member. Therefore, the electrodynamic speaker provided with these magnetic circuits can reduce the influence of the sound emitted by the vibration of the copper cap 16 on the reproduction sound quality, and can secure a good reproduction sound quality. In other words, the copper cap 16 is provided to increase the reproduced sound pressure level in the high sound range of the electrodynamic speaker, or to improve the distortion characteristics. It is possible to improve the reproduction sound quality by suppressing the vibration radiation sound.

  The repulsive magnetic circuit 17 and the external magnetic type magnetic circuit 30 described in Example 1 and the external magnetic type magnetic circuit 40 described in Example 2 are similarly provided as conductive members. The vibration radiation sound which the copper cap 16 vibrates and radiates | emits can be suppressed by providing a damping member, respectively. Therefore, the electrodynamic speaker provided with these magnetic circuits can reduce the influence of the sound emitted by the vibration of the copper cap 16 on the reproduction sound quality, and can secure a good reproduction sound quality.

  The conductive member included in the magnetic circuit of the present invention is not limited to the copper cap described in the above embodiment, but may be a ring formed of an alloy containing aluminum or the like that is nonmagnetic and has low electrical resistance. Even if the overall shape of the conductive member is a cap shape or a ring shape, the conductive member extends in a substantially perpendicular direction from the conductive flat surface portion and the outer peripheral end of the conductive flat surface portion. As long as it is fixed to the magnetic path constituent member so as to cover the inner peripheral side of the magnetic gap formed in the magnetic circuit. This is because the conductive member having the conductive cylindrical portion acts so as to lower the inductance component of the electrical impedance by being positioned in the vicinity of the voice coil.

  Moreover, although the magnetic circuit structural member demonstrated in the said Example was a member formed with metals, such as iron with high magnetic permeability, such as a yoke, a plate, and a pole, it is not limited to these metals. The magnetic circuit constituent member may be a magnetic body such as ferrite, or may be a member having a high magnetic permeability that contains a metal or ferrite powder in a resin.

  Moreover, although the electrodynamic speaker demonstrated in the said Example is an electrodynamic speaker which uses a cone-type diaphragm, the structure of an electrodynamic speaker is not restricted to a present Example. The cone-type diaphragm may be a planar diaphragm, and the configuration of the electrodynamic speaker may be a small speaker without a damper, a tweeter for high-frequency reproduction, or the like.

  The magnetic circuit of the present invention can be applied not only as an electrodynamic speaker, but also to an electrodynamic microphone magnetic circuit that converts sound into an electric signal, or an electrodynamic exciter that converts an audio signal into vibration. Is possible. The magnetic circuit of the present invention is particularly suitable for a tweeter for high-frequency range reproduction or a micro speaker having a small and thin diaphragm because the high-frequency range reproduction capability is improved.

It is a figure explaining the electrodynamic speaker 1 by preferable embodiment of this invention. Example 1 It is a figure explaining the other magnetic circuit which comprises the electrodynamic type speaker by other preferable embodiment of this invention. Example 1 It is a figure explaining the other magnetic circuit which comprises the electrodynamic type speaker by other preferable embodiment of this invention. (Example 2) It is a figure explaining the magnetic circuit of the comparative example which comprises the conventional electrodynamic type speaker as a comparative example. (Comparative example) It is a graph of the sound pressure frequency characteristic in the magnetic circuit for measurement. (Examples and comparative examples) It is a graph of the electrical impedance characteristic of the magnetic circuit for a measurement. (Examples and comparative examples)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrodynamic type speaker 2 Cone type diaphragm 3 Voice coil 4 Edge 5 Damper 6 Frame 7 Dust cap 8 Kinshi wire 9 Terminal 10, 30, 50, 60, 70, 80 Inner magnet type magnetic circuit 17 Repulsive type magnetic circuit 20, 40 outer magnet type magnetic circuit 11, 21 magnet 12 center plate 13 yoke 15, 19, 25, 35, 45, 55, 65, 75, 85 magnetic gap 16 copper cap 18 repulsive magnet 23, 43 pole 24 top plate 37 elastic body 38 Mass 72 Center plate 76 Copper plate

Claims (7)

A magnet, a plurality of magnetic path constituent members that form a magnetic path having an annular magnetic gap together with the magnet, a conductive flat surface, and a conductive material extending in a substantially perpendicular direction from the outer peripheral side end of the conductive flat surface A conductive member having a cylindrical part, and a damping member for suppressing vibration of the conductive flat part of the conductive member,
The conductive cylindrical portion of the conductive member is fixed to the magnetic path constituent member so as to cover the inner peripheral side of the magnetic gap,
The damping member is fixed to one surface of the conductive flat portion of the conductive member.
Magnetic circuit. The damping member is a center plate that also serves as the magnetic path constituting member and forms the magnetic path and the inner peripheral side of the magnetic gap,
The plurality of magnetic path constituent members include a yoke that forms an outer peripheral side of the magnetic gap,
Fixing one surface of the conductive flat portion of the conductive member to the bottom surface of the center plate, and fixing the conductive cylindrical portion of the conductive member to a side surface of the center plate;
Fixing one surface of the magnet to the other surface of the conductive flat portion of the conductive member;
Fixing the inner bottom surface of the yoke to the other surface of the magnet;
The magnetic circuit according to claim 1. A repulsion magnet magnetized in a direction opposite to the magnetizing direction of the magnet, and a bottom surface of the repulsion magnet is fixed to the upper surface of the center plate;
The magnetic circuit according to claim 2. The damping member is a center plate that also serves as the magnetic path constituting member and forms the magnetic path and the inner peripheral side of the magnetic gap,
The plurality of magnetic path components include a pole and a top plate that forms the outer peripheral side of the magnetic gap,
Fixing one surface of the conductive flat portion of the conductive member to the bottom surface of the center plate, and fixing the conductive cylindrical portion of the conductive member to a side surface of the center plate;
The convex portion of the pole is fixed to the other surface of the conductive flat portion of the conductive member,
The bottom surface of the magnet is fixed to the under plate of the pole,
The top plate is fixed to the upper surface of the magnet.
The magnetic circuit according to claim 1. The vibration damping member fixed to one surface of the conductive flat portion of the conductive member includes a flat plate-like elastic body, and a non-magnetic and non-conductive mass body fixed to the elastic body so as to vibrate. And
The plurality of magnetic path constituent members include a center plate that forms an inner peripheral side of the magnetic gap, and a yoke that forms an outer peripheral side of the magnetic gap,
Fixing the other surface of the conductive flat portion of the conductive member to the upper surface of the center plate, and fixing the conductive cylindrical portion of the conductive member to the side surface of the center plate;
The upper surface of the magnet is fixed to the bottom surface of the center plate,
Fixing the inner bottom portion of the yoke to the bottom surface of the magnet;
The magnetic circuit according to claim 1. The vibration damping member fixed to one surface of the conductive flat portion of the conductive member includes a flat plate-like elastic body, and a non-magnetic and non-conductive mass body fixed to the elastic body so as to vibrate. And
The plurality of magnetic path components include a pole that forms an inner peripheral side of the magnetic gap, and a top plate that forms an outer peripheral side of the magnetic gap,
Fixing the other surface of the conductive planar portion of the conductive member to the convex portion of the pole, and fixing the conductive cylindrical portion of the conductive member to the side surface of the convex portion of the pole;
The bottom surface of the magnet is fixed to the under plate of the pole,
The top plate is fixed to the upper surface of the magnet.
The magnetic circuit according to claim 1.   A diaphragm, a voice coil having a bobbin wound around the coil and connected to the diaphragm, an edge supporting the outer peripheral end of the diaphragm, and an inner peripheral end of the diaphragm connected to the bobbin A magnetic circuit according to any one of claims 1 to 6, wherein a damper is provided for supporting the edge, a frame for fixing the edge and the outer peripheral end of the damper, and a coil connected to the frame to dispose the coil in the magnetic gap. And an electrodynamic speaker.

Images