JP2010103891A - Magnetic circuit for speaker, and electrodynamic speaker using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic circuit for, in particular, an elongated electrodynamic speaker having a major-axis direction and a minor-axis direction, excelling in sound reproduction capability, and suitable for attachment to an apparatus such as a display, and an electrodynamic speaker, in relation to a thin electrodynamic speaker having a thin magnetic circuit. <P>SOLUTION: The magnetic circuit for a speaker includes: an annular top plate having two parallel linear parts at the inner peripheral side, a pole having two projection parts cut and raised from an under plate at the inner peripheral side, and two rod-like magnets magnetized in the same direction. In the magnetic circuit, the two projection parts of the pole face the two linear parts of the top plate to form two magnetic air gaps arranged between the magnets, the two projection parts of the pole form a through-hole between them, and the top plate, the under plate and the magnets form two internal spaces communicating with the through-hole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thin electrodynamic speaker having a thin magnetic circuit, and in particular, is an elongated electrodynamic speaker having a short minor axis direction shorter than a major axis direction, which has excellent sound reproduction capability, such as a display. The present invention relates to a speaker magnetic circuit suitable for being attached to a device, and an electrodynamic speaker.

  In an audio device such as a display to which a speaker for reproducing sound is attached, it is desired to reduce the space required for attaching the speaker. In particular, in an electrodynamic speaker intended to be thin, there are cases where there is a limit to thinning depending on the configuration of the magnetic circuit. In addition, slender (rectangular, oval (including elliptical, track-shaped)) electrodynamic speakers employ a speaker magnetic circuit with a high magnetic flux density in the magnetic gap, where the diaphragm area is limited in the minor axis direction. When trying to do so, there is a disadvantage in the sound reproduction capability for various reasons such as the magnetic circuit is wider than the speaker diaphragm and cannot be downsized. Therefore, in order to solve these problems, various magnetic circuits for speakers and electrodynamic speakers using the same have been proposed.

  For example, conventionally, in order to reduce the thickness of an electrodynamic speaker, a magnetic circuit including a magnet, a plate, and a yoke, a frame coupled to the magnetic circuit, and a diaphragm coupled to the frame The speaker is composed of a voice coil coupled to the diaphragm, a part of which is disposed in the magnetic gap of the magnetic circuit, and a damper that supports the voice coil in the magnetic gap. There is a speaker that has at least one through hole, and one of the dampers is coupled to the frame, and the other is configured to support the lower part of the voice coil after passing through the through hole of the yoke (patent) Reference 1).

  Further, for example, a magnetic circuit in which at least two bar-shaped magnets are sandwiched in parallel by sandwiching a bar-shaped center pole portion provided on the lower plate between the upper plate and the lower plate, and a frame coupled to the magnetic circuit, A speaker comprising a diaphragm coupled to an outer peripheral portion of the frame, and a voice coil coupled to the diaphragm and part of which is disposed in a magnetic gap of the magnetic circuit, There is a speaker having two straight portions in which a shape of a magnetic gap composed of a plate and the lower plate is at least parallel (Patent Document 2).

  Further, a casing of the speaker is formed by combining a metal yoke and a frame, a magnet is disposed at the center of the metallic yoke inside the casing, a metal plate is disposed on the surface of the magnet, and the casing is attached to the casing. A speaker device having a diaphragm having a fixed outer periphery and a rectangular parallelepiped drive coil fixed to a central portion of one surface of the diaphragm and having a winding axis perpendicular to the diaphragm. A metal yoke has a speaker device in which a part of the long side of a rectangular sheet metal is cut and raised, and the four corners of the rectangle are protrusions (Patent Document 3).

JP 2003-339099 A JP 2004-266337 A JP 2004-128822 A

  However, in an elongated electrodynamic speaker with a shorter minor axis direction compared to the major axis direction, if the damper is omitted in order to reduce the thickness, the operation of the vibration system tends to become unstable, and the voice coil is magnetically connected to the magnetic circuit. There is a case where abnormal noise is generated in contact with the air gap, causing a problem of malfunction. In addition, if the entire electrodynamic speaker including the frame and magnetic circuit is made thin, the diaphragm contacts the frame or the damper contacts the magnetic circuit when an audio signal with a large amplitude is supplied to the voice coil. Problems are likely to occur.

  The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention relates to a thin electrodynamic speaker having a thin magnetic circuit, and in particular, a short diameter direction compared to a long diameter direction. It is an object of the present invention to provide a magnetic circuit for a speaker and an electrodynamic speaker that are excellent in sound reproduction capability and are suitable for being attached to a device such as a display.

  A magnetic circuit for a speaker according to the present invention includes an annular top plate having two linear portions parallel to the inner peripheral side, a pole having two protrusions cut and raised from the under plate on the inner peripheral side, a top plate, Two rod-shaped magnets sandwiched between the pole's under plates and magnetized in the same direction, with the two projections of the pole facing the two straight portions of the top plate, respectively, Two magnetic gaps are formed between the rod-shaped magnets, the two protrusions of the pole form a through hole between them, and the top plate, the under plate, and the two rod-shaped magnets penetrate Two internal spaces communicating with the hole are formed.

  Preferably, the magnetic circuit for a speaker according to the present invention further includes a buffer member that is sandwiched between the two protrusions of the pole and attached to the approximate center of the through hole.

  Preferably, in the magnetic circuit for a speaker according to the present invention, the top plate and the pole have an elongated shape having a major axis direction and a minor axis direction, two magnetic gaps are provided along the major axis direction, and Two internal spaces are arranged along the major axis direction with a through hole interposed therebetween.

  Preferably, the electrodynamic loudspeaker of the present invention has the above-described speaker magnetic circuit, a frame connected to the speaker magnetic circuit, an edge whose outer peripheral end is fixed to the frame, and an outer peripheral end thereof by the edge. A speaker diaphragm to be supported, an elongated shape including two linear portions along the major axis direction, a bobbin whose one end is connected to the center of the speaker diaphragm, and wound around the bobbin into two magnetic gaps Connects the coil where the straight part is arranged, the two inner fixing parts where the other end of the bobbin is connected, the outer fixing part fixed to the top plate of the speaker magnetic circuit, and the inner fixing part and the outer fixing part And a damper having an inner flat part for connecting the two inner fixing parts, and the two movable parts of the damper are disposed in the internal space of the speaker magnetic circuit. Each is arranged, and the inner flat portion of the damper, the two inner fixed portion, for connecting across the through-hole of the magnetic circuit for the speaker along the major axis direction.

  Preferably, the electrodynamic speaker of the present invention further includes a connection reinforcing member that connects the rear center portion of the speaker diaphragm and the inner flat portion of the damper.

  More preferably, the electrodynamic speaker of the present invention is the above electrodynamic speaker provided with a buffer member, and an inner flat portion of the damper is connected to the buffer member.

  Hereinafter, the operation of the present invention will be described.

  A magnetic circuit for a speaker according to the present invention includes an annular top plate having two linear portions parallel to the inner peripheral side, a pole having two protrusions cut and raised from the under plate on the inner peripheral side, a top plate, The magnetic circuit includes two rod-like magnets sandwiched between pole under plates and magnetized in the same direction. Preferably, the top plate and the pole have an elongated shape having a major axis direction and a minor axis direction, and the pole has two protrusions formed by cutting and raising a flat plate-like under plate at two linear portions of the top plate. Opposing each other, two magnetic gaps are formed between two bar-shaped magnets. The major axis direction is a direction in which a major axis defining a rectangle, an ellipse, an ellipse, or an elongated shape including a track shape extends, and the minor axis direction is a direction in which a minor axis orthogonal to the major axis extends. It is.

  The two magnetic gaps are provided along the major axis direction, and the two internal spaces are arranged along the major axis direction with a through hole interposed therebetween. As a result, the two protrusions of the pole form a through hole between them, and the top plate, the under plate, and the two bar-shaped magnets form two internal spaces that communicate with the through hole. Therefore, the magnetic circuit for a speaker according to the present invention is sandwiched between the two protrusions of the pole, and a buffer member can be further attached at substantially the center of the through hole. Moreover, the damper which comprises an electrodynamic type speaker can be provided using two internal space connected to a through-hole.

  In other words, the electrodynamic speaker of the present invention is supported by the speaker magnetic circuit, the frame connected to the speaker magnetic circuit, the edge whose outer peripheral end is fixed to the frame, and the outer peripheral end supported by the edge. A speaker diaphragm, and an elongated shape including two linear portions along the major axis direction, and a bobbin whose one end is connected to the center of the speaker diaphragm, and each of the two magnetic gaps wound around the bobbin. 2 connecting the inner fixing portion and the outer fixing portion, the outer fixing portion fixed to the top plate of the magnetic circuit for the speaker, the two inner fixing portions to which the other end of the bobbin is connected, A damper having two movable parts and an inner flat part connecting the two inner fixed parts. A voice coil including an elongated bobbin and a coil is typically a shape including two straight portions along a major axis direction of a rectangular shape and a track shape, and the frame, the edge, and the speaker diaphragm are elongated. Thus, it is possible to realize an electrodynamic speaker that has a short length in the minor axis direction (that is, a narrow width) and is suitable for being attached to a device such as a display.

  In addition, in the electrodynamic speaker of the present invention, the damper has two movable parts and an inner flat part that connects the two inner fixed parts, corresponding to the magnetic circuit for the speaker. Are disposed in the interior space of the speaker magnetic circuit, and the inner flat portion of the damper crosses the two inner fixed portions across the through hole of the speaker magnetic circuit along the major axis direction. Link. Therefore, the movable part of the damper supports the voice coil so that it can vibrate so as not to interfere with the magnetic circuit in the internal space provided on both ends in the major axis direction with respect to the through hole. The overall height of the portion can be reduced to reduce the thickness.

  Also, the inner flat part of the damper connects the two inner fixing parts along the major axis direction so that the inner peripheral side of the bobbin crosses the through hole of the magnetic circuit for the speaker, so that the voice coil can be stabilized. It can be supported so that it can vibrate. Preferably, in the case of further including a connection reinforcing member that connects the rear center portion of the speaker diaphragm and the inner flat portion of the damper, the central portion of the speaker diaphragm that easily generates divided vibration is connected to the inner flat portion of the damper. Since they are connected, the operation of the electrodynamic speaker can be stabilized.

  The shock-absorbing member sandwiched between the two protrusions of the magnetic circuit pole for the speaker is specifically a member that forms a resin foam, rubber, or elastomer represented by urethane foam into a substantially rectangular parallelepiped shape. Is suitable, and may be fixed with an adhesive between the two protrusions. The buffer member is attached to substantially the center of the through hole, and the inner flat portion of the damper is connected to the buffer member. Since the buffer member is connected to the inner flat portion of the damper, when the speaker vibration system including the voice coil vibrates, the buffer member expands and contracts to support the damper from the inner side. The buffer member can prevent the voice coil and the damper from coming into contact with the magnetic circuit to generate abnormal noise, thereby reducing malfunctions.

  Further, the pole of the magnetic circuit for the speaker cuts and raises (or bends up) the inner peripheral side of the annular flat plate constituting the under plate to form two protrusions that form a magnetic gap. Therefore, a magnetic circuit can be constructed at a low cost by a simple method, and the whole can be thinned. The magnetic circuit for a speaker according to the present invention has two magnetic gaps arranged between two rod-shaped magnets by an inner peripheral side of an annular plate and a protrusion cut and raised on the inner peripheral side of the pole. Since it is an external magnetic type magnetic circuit to be formed, the length of the magnetic gap including the linear portion along the major axis direction is shorter than that of the two rod-shaped magnets. Therefore, magnetic flux concentrates in the magnetic gap, and even with a thin magnetic circuit, a high magnetic flux density distribution can be obtained, improving the efficiency of the electrodynamic speaker and realizing an electrodynamic speaker with excellent reproduction sound quality it can.

  For thin electrodynamic speakers with thin magnetic circuits, especially slender electrodynamic speakers with a shorter minor axis direction compared to the major axis direction, with excellent sound reproduction capability, and attached to devices such as displays A magnetic circuit for a speaker and an electrodynamic speaker suitable for the above can be provided.

  For thin electrodynamic speakers with thin magnetic circuits, especially slender electrodynamic speakers with a shorter minor axis direction compared to the major axis direction, with excellent sound reproduction capability, and attached to devices such as displays For the purpose of providing a magnetic circuit for a speaker and an electrodynamic speaker suitable for a speaker, the magnetic circuit for the speaker has an annular top plate having two straight portions parallel to the inner peripheral side, and an under plate on the inner peripheral side A pole having two protrusions cut and raised from the top, and two rod-like magnets sandwiched between the top plate and the underplate of the pole and magnetized in the same direction, and two protrusions of the pole Two magnetic gaps are formed between the two bar-shaped magnets so that the two portions are opposed to the two straight portions of the top plate. Protrusion, a through hole is formed therebetween, the top plate and the under plate and two bar-shaped magnet, by so as to form two inner space communicating the through-hole, was realized.

  Hereinafter, although the magnetic circuit for speakers and the 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 perspective view of the electrodynamic speaker 1 viewed from the front side, and FIG. 1B is a perspective view of the electrodynamic speaker 1 viewed from the back side. FIG. 2 is a development view illustrating the configuration of the electrodynamic speaker 1. FIG. 3 is an enlarged view for explaining the configuration of the electrodynamic speaker 1 when the speaker diaphragm 2 is removed. As will be described later, a part of the structure of the electrodynamic speaker 1, the internal structure, and the like are omitted. Further, the direction in which the straight line (long axis) connecting the points A-O-A ′ extends is the major axis direction, and the point OB
The direction in which the straight line (minor axis) connecting the two extends is the minor axis direction.

  The electrodynamic speaker 1 of this embodiment is an elongated electrodynamic speaker having a track-shaped speaker diaphragm 2 having a major axis length L1 of about 262.5 mm and a minor axis direction length L2 of about 26.0 mm. The speaker has a diaphragm area equivalent to that of a circular diaphragm having an aperture of about 130 mm even though it is elongated. The outer peripheral end of the speaker diaphragm 2 is supported by an edge 3, and the outer peripheral end of the edge 3 is fixed to the frame 6. A voice coil 4 is connected to the back side of the speaker diaphragm 2 and is supported by a damper 5 so as to vibrate. In the case of the present embodiment, the voice coil 4 has a track shape having a major axis length of about 32.8 mm and a minor axis direction length of about 13.6 mm. Further, the frame 6 has an elongated shape corresponding to the track-shaped speaker diaphragm 2, and the magnetic circuit 10 fixed so as to be accommodated in the frame 6 also has an elongated shape having a narrow width of the minor axis direction length L2 or less. Have. Therefore, the electrodynamic speaker 1 is a speaker suitable for a device with a small width for mounting the speaker, such as a side surface of a display unit included in a device such as a display. A terminal 7 to which an audio signal current is supplied is attached to the back side of the frame 6 and a part of the magnetic circuit 10 is exposed.

  The speaker diaphragm 2 of the electrodynamic speaker 1 has an inner peripheral side of the edge 3 bonded to the outer peripheral end thereof, and a bobbin 4a constituting the voice coil 4 is bonded to the center rear surface. The speaker diaphragm 2 is formed by forming a foamed thermoplastic resin in order to reduce the weight of the speaker diaphragm. In the case of the present embodiment, the speaker diaphragm 2 having irregularities is obtained by using a vacuum forming method in which a thermoplastic resin foam sheet (specifically, polystyrene paper) that has been extruded is combined with plug assist molding. It has gained. That is, in the elongated speaker diaphragm 2 in which the major axis direction length L1 and the minor axis direction length L2 are remarkably different, the influence of divided vibration in the major axis direction is likely to be noticeable, so the minor axis direction cross-sectional shape includes a substantially U-shape. Thus, the shape has rigidity in the major axis direction.

  In this embodiment, the edge 3 is formed by injecting flexible foam rubber into a mold and heating and foaming. On the long side of the track shape extending linearly in the major axis direction of the speaker diaphragm 2, a free edge is formed by a thin corrugation (or roll) so as to freely support the speaker diaphragm 2, and an arc shape is formed in the minor axis direction. On the short side of the track shape, a fixed edge that does not vibrate freely is formed so as to fix and support the speaker diaphragm 2. As a result, the elongated speaker diaphragm 2 is flexibly supported by the compliance of the free edge portion of the edge 3 in the minor axis direction, while the thermoplastic resin foam sheet that forms the speaker diaphragm 2 in the major axis direction. Flexibility enables bending vibration.

  The voice coil 4 is formed by a bobbin 4a formed in a track shape and a track-shaped coil 4b wound around one end thereof and supplied with a sound current. The other end of the bobbin 4a around which the coil 4b is not wound is connected to the center of the back surface of the speaker diaphragm 2 with an adhesive. Since the track-shaped bobbin 4a and the coil 4b include two straight portions along the major axis direction, the two straight portions of the coil 4b are respectively disposed in magnetic gaps 13a and 13b of the magnetic circuit 10 described later. Note that the tinsel wire (not shown) supplies the audio current to the coil 4b by soldering the terminal 7 fixed to the frame 6 and the lead wire of the coil 4b from the terminal 7 to be conducted. However, the tinsel wire may be electrically connected to the terminal 7 by providing a metal eyelet on the speaker diaphragm 2.

  The damper 5 is formed by cutting an elongated corrugation damper formed by impregnating a phenolic resin with a woven fabric of flexible fibers as a base material and forming an overall shape. Specifically, the damper 5 includes two inner fixing portions 5a connected to the end side around which the coil 4b of the bobbin 4a is wound, and an outer fixing portion 5b fixed to the top plate 11 of the speaker magnetic circuit 10. , Two movable parts 5c that connect the inner fixed part 5a and the outer fixed part 5b, and an inner flat part 5d that connects the two inner fixed parts 5a. The two movable portions 5c of the damper positioned in the major axis direction have a substantially fan shape and have corrugations, and are respectively disposed in the internal spaces 16a and 16b of the speaker magnetic circuit 10 as described later. Further, the inner flat portion 5d of the damper is an elongated strip-shaped flat portion, and connects the two inner fixing portions 5a across the through hole 14 of the speaker magnetic circuit 10 along the major axis direction.

  The frame 6 is an iron plate frame that is press-molded into an elongated basket shape corresponding to the shape of the speaker diaphragm 2. The frame 6 has a substantially rectangular fixing portion that fixes the edge 3, and a fixing portion that fixes the magnetic circuit 10. A connecting portion for connecting these fixing portions, a window defined between the plurality of connecting portions, and a mounting hole for attaching the terminal 7 are provided. Therefore, the speaker vibration system including the speaker diaphragm 2, the edge 3, the voice coil 4, and the damper 5 is supported so as to be capable of vibrating with respect to the frame 6 and the magnetic circuit 10.

  FIG. 4 is a perspective view for explaining the magnetic circuit 10 constituting the electrodynamic speaker 1. FIG. 5 is a perspective view for explaining the top plate 11 constituting the magnetic circuit 10. The magnetic circuit 10 includes an elongated top plate 11, an elongated pole 12, and two rod-shaped magnets 15a and 15b magnetized in the same direction. Each member constituting the magnetic circuit 10 is fixed with an adhesive. The magnetic circuit 10 is also fixed to the fixing portion of the frame 6 with an adhesive. The magnetic circuit 10 is a thin magnetic circuit having an overall height of about 6.6 mm. Since the entire magnetic circuit 10 is accommodated inside the frame 6, the electrodynamic speaker 1 can be thinned.

  The top plate 11 is formed of a soft iron steel material having a major axis length of 50.0 mm, a minor axis direction length of 24.0 mm, and a thickness of 1.6 mm in an annular shape having two linear portions 11a and 11b parallel to the inner peripheral side. It is a member. The two linear portions 11a and 11b are provided along the major axis direction, have a length of 24.0 mm, and form magnetic gaps 13a and 13b described later. That is, the top plate 11 has such a shape that two long straight portions 11a and 11b extending in the major axis direction from the inner peripheral side of the rectangular ring protrude into a trapezoidal shape, and the two straight portions 11a and 11b The other annular inner peripheral side does not act as a magnetic gap for generating a driving force for the voice coil 4.

  The pole 12 is a member having two protrusions 12a and 12b cut and raised from the under plate 12u on the inner peripheral side. Specifically, as shown in FIG. 5A, on the inner peripheral side of a soft iron steel material having a major axis direction length of 50.0 mm, a minor axis direction length of 24.0 mm, and a thickness of 1.6 mm constituting the under plate 12u. A substantially H-shaped hole is provided, and as shown in FIG. 5 (b), these are cut and raised from the inner peripheral side so as to have two protrusions 12a and 12b. In the pole 12, the straight hole of the horizontal bar portion constituting the substantially H-shaped hole is along the major axis direction so that the two protrusions 12 a and 12 b face the two straight parts of the top plate, respectively. Placed in the direction The pole 12 may be implemented in a single process of punching and bending.

  The two rod-shaped magnets 15a and 15b are rare earth magnets each having a major axis length of 50.0 mm, a minor axis direction length of 6.0 mm, and a thickness of 3.0 mm, and may be ferrite magnets. The rare earth magnet is an Nd—Fe—B type neodymium magnet or an Sm—Co type samarium cobalt magnet, which has a large maximum energy product (BH) max, An Nd—Fe—B rare earth magnet having a larger magnetization and coercive force and a strong coercive force even in a small volume may be used.

  Therefore, in the magnetic circuit 10, the two protrusions 12 a and 12 b of the pole 12 are disposed between the two bar-shaped magnets 15 a and 15 b so as to face the two straight portions 11 a and 11 b of the top plate 11, respectively. Two magnetic gaps 13a and 13b are formed. The two magnetic gaps 13a and 13b are provided along the major axis direction, and the two protrusions 12a and 12b of the pole 12 form a substantially rectangular through hole 14 therebetween. The top plate 11, the underplate 12 u of the pole 12, and the two rod-shaped magnets 15 a and 15 b form two internal spaces 16 a and 16 b communicating with the through hole 14. In the elongated magnetic circuit 10 of this embodiment, the two internal spaces 16a and 16b are disposed along the major axis direction with the through hole 14 interposed therebetween.

  FIG. 6 is a plan view illustrating the magnetic circuit 10, the voice coil 4, and the damper 5 that constitute the electrodynamic speaker 1. FIG. 7 is an enlarged view of the AO-A ′ cross section along the major axis direction for explaining the configuration in the vicinity of the magnetic circuit 10 of the electrodynamic speaker 1 of the present embodiment.

  In the electrodynamic speaker 1, when an audio current is supplied to the coil 4b of the voice coil 4, a driving force acts on the linear portions of the voice coil 4 arranged in the magnetic gaps 13a and 13b. 7 and the connected speaker diaphragm 2 vibrate in the vertical direction. The speaker diaphragm 2 is flexibly supported by the free edge portion of the edge 3 that supports the outer peripheral end thereof in the minor axis direction. On the other hand, in the major axis direction, bending vibration is possible due to the flexibility of the thermoplastic resin foam sheet forming the speaker diaphragm 2, and the voice coil 4 is greatly displaced at a frequency near or below the lowest resonance frequency f0. The speaker diaphragm 2 fixed at both ends in the major axis direction is bent and deformed in an arc shape in the major axis direction.

  The damper 5 that supports the track-type voice coil 4 so as to vibrate is fixed at its outer fixing portion 11 b on the plane of the annular top plate 11 that constitutes the magnetic circuit 10. The two inner fixing portions 5a connected to the voice coil 4 of the damper 5 are arc-shaped recesses corresponding to the short-diameter side of the track shape, and the end portion on the side where the coil 4b of the bobbin 4a is wound is provided. It is a part fixed so that it may be mounted. Therefore, in the damper 5, the inner flat portion 5 d that connects the two inner fixing portions 5 a arranged in the major axis direction can be integrally formed on the inner peripheral side of the voice coil 4. The inner flat portion 5d of the damper connects the two inner fixing portions 5a across the through hole 14 of the speaker magnetic circuit 10 along the major axis direction, and reinforces the track-shaped bobbin 4a. That is, in the electrodynamic speaker 1 of this embodiment, since the speaker magnetic circuit 10 has the through hole 14, the inner peripheral side of the bobbin 4a is extended along the major axis direction by the inner flat portion 5d of the damper 5. The voice coil 4 can be stably supported so as to vibrate.

  The magnetic circuit 10 is an external magnet type magnetic circuit in which a magnet is arranged outside a region to be projected when the coil 4b of the voice coil 4 is viewed in plan, and rod-like magnets 15a and 15b having a strong coercive force have a long diameter. Since it is arranged so as to extend in the direction, it is suitable for an elongated speaker such as the electrodynamic speaker 1 of the present invention. This is because if the maximum width of the magnetic circuit 10 can be reduced, the magnetic circuit 10 can be accommodated in a region formed when the elongated speaker diaphragm 2 is viewed from the front. In the magnetic circuit 10, the lengths of the magnetic gaps 13a and 13b including the straight portions 11a and 11b along the major axis direction are shorter than those of the rod-shaped magnets 15a and 15b. Therefore, magnetic flux concentrates in the magnetic gaps 13a and 13b, and a high magnetic flux density distribution can be obtained even with the thin magnetic circuit 10. Therefore, including the use of the lightweight speaker diaphragm 2, the highly efficient electrodynamic speaker 1 is realized.

  In addition, in the electrodynamic speaker 1, the two movable portions 5 c of the damper 5 are arranged in the internal spaces 16 a and 16 b of the speaker magnetic circuit 10 in correspondence with the speaker magnetic circuit 10. The two movable portions 5c of the damper positioned in the major axis direction are portions that are substantially fan-shaped, have corrugations, and are respectively disposed in the internal spaces 16a and 16b that are not used as magnetic gaps. The two movable parts 5c of the damper 5 can support the voice coil 4 so as to be able to vibrate so as not to interfere with the magnetic circuit 10, respectively. Therefore, the electrodynamic speaker 1 can be thinned by reducing the overall height of the magnetic circuit 10 of the electrodynamic speaker so that the entire magnetic circuit 10 is accommodated in the frame 6.

  The electrodynamic speaker 1 of this embodiment is a case in which a frame 6 that accommodates almost the entire speaker magnetic circuit 10 is used, but its bottom is connected to the top plate 11 of the speaker magnetic circuit 10. Even with a conventional frame, the thickness can be sufficiently reduced. Even in the case of an elongated electrodynamic speaker in which the operation of the vibration system is likely to be unstable, the electrodynamic speaker 1 of the present embodiment generates an abnormal noise when the voice coil contacts the magnetic gap of the magnetic circuit, The problem of malfunction can be suppressed.

  FIG. 8 is a diagram for explaining an electrodynamic speaker 1a according to another embodiment of the present invention. AO-A ′ along the major axis direction illustrating the configuration of the electrodynamic speaker 1a in the vicinity of the magnetic circuit 10. It is an enlarged view of a cross section.

  The electrodynamic loudspeaker 1a of this embodiment is connected to the electrodynamic loudspeaker 1 of the previous embodiment 1 to connect the back center part 2d of the speaker diaphragm 2 and the inner flat part 5d of the damper 5 to each other. The electrodynamic speaker further includes the member 8, and the other configuration is a common electrodynamic speaker. In addition, except for what will be described later, portions common to those constituting the electrodynamic speaker 1 described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Specifically, the connection reinforcing member 8 is a lightweight and strong resin foam having a thickness of 21.0 mm, or a member in which a honeycomb material is formed in a substantially rectangular parallelepiped shape. And the inner flat portion 5d of the damper 5 are fixed with an adhesive. Since the magnetic circuit 10 has the through hole 14, the connection reinforcing member 8 is disposed in the through hole 14, and the central portion of the speaker diaphragm 2 and the inner peripheral side of the bobbin 4a are connected along the major axis direction. The inner flat part 5d of the damper 5 to be connected can be connected.

  Since the connection reinforcing member 8 suppresses the vibration at the central portion of the speaker diaphragm 2 that easily generates divided vibrations, the operation of the electrodynamic speaker 1a can be stabilized. The inner flat portion 5d of the damper 5 to which the connection reinforcing member 8 is attached acts to support the voice coil 4 from the inner side. As described above, the inner flat portion 5 d of the damper 5 is an elongated strip-shaped flat portion, and thus exhibits elasticity so as to support the connection reinforcing member 8. As a result, the electrodynamic speaker 1a is less likely to generate abnormal noise than the electrodynamic speaker 1 of the previous embodiment, and the malfunction can be reduced.

  The connection reinforcing member 8 may be replaced by providing a deeper recess at the center of the back surface of the speaker diaphragm 2 and connecting it to the inner flat portion 5d of the damper 5. Further, the connection reinforcing member 8 may be a dust cap that covers the upper end side of the bobbin 4 a of the voice coil 4.

  FIG. 9 is a diagram for explaining an electrodynamic speaker 1b according to another embodiment of the present invention. AO-A ′ along the major axis direction explaining the configuration of the electrodynamic speaker 1b in the vicinity of the magnetic circuit 10. It is an enlarged view of a cross section.

  The electrodynamic speaker 1b of the present embodiment is a buffer member 9 that is sandwiched between the two protrusions 12a of the pole 12 of the speaker magnetic circuit 10 with respect to the electrodynamic speaker 1 of the first embodiment. The other structure is a common electrodynamic speaker. In addition, except for what will be described later, portions common to those constituting the electrodynamic speaker 1 described in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The shock-absorbing member 9 is a member in which a flexible resin foam, rubber, or elastomer is formed in a substantially rectangular parallelepiped shape, and specifically, a cushion made of a foamed urethane material having a foaming ratio of about 40 times is about thickness. 5 mm and cut into 10 mm × 12 mm. The shock-absorbing member 9 is fixed between the two protrusions 12a of the pole 12 of the speaker magnetic circuit 10 so as to be held with a flexible adhesive even after curing. That is, the buffer member 9 is an elastic member that is attached to substantially the center of the through hole 14 of the speaker magnetic circuit 10 and is disposed so as to occupy a part of the through hole 14. The buffer member 9 may be attached to the through hole 14 in the step of pre-assembling the speaker magnetic circuit 10 shown in FIG. 4 before assembling the electrodynamic speaker 1b.

  When the electrodynamic speaker 1b is assembled, the buffer member 9 attached to the approximate center of the through hole 14 is bonded to the inner flat portion 5d of the damper 5 constituting the speaker vibration system that is also arranged so as to cross the through hole 14. Connected with agents. Therefore, when the speaker vibration system including the voice coil 4 vibrates, the buffer member 9 expands and contracts and supports the damper 5 so that it can vibrate from the inside. Since the buffer member 9 keeps the speaker vibration system at the center, the coil 4b is prevented from contacting the magnetic air gaps 13a and 14b, or the damper 5 is prevented from contacting the magnetic circuit 10 to generate an abnormal noise, resulting in malfunction. Can be reduced.

  FIG. 10 is a graph showing the sound pressure frequency characteristic and the harmonic distortion characteristic of the electrodynamic speaker of the present invention. FIG. 10A shows the case of the electrodynamic speaker 1 shown in the previous embodiment, and FIG. 10B shows the case of the electrodynamic speaker 1b of this embodiment further including the buffer member 9. FIG. . The sound pressure frequency characteristic indicates a sound pressure level in terms of 1 W / 1 m, and the harmonic distortion characteristic is displayed with +30 dB of the seventh to tenth harmonic distortions. Compared with the case of the electrodynamic speaker 1, the electrodynamic speaker 1b further provided with the buffer member 9 does not substantially change the lowest resonance frequency f0, and maintains the performance of low-frequency reproduction even if the buffer member 9 is provided. be able to. Further, in the electrodynamic speaker 1b, the divided vibration generated in the damper 5 is suppressed, and high-order harmonic distortion that has a great influence when reproducing the timbre can be reduced. It is an excellent electrodynamic speaker.

  In the electrodynamic speaker 1 of the present invention, the speaker diaphragm 2 is not limited to an elongated track shape, and if the voice coil 4 is an elongated shape having two parallel straight portions, the speaker diaphragm 2 The outer shape may be an oblong, oblong, rectangular or rectangular shape having a large ratio of the major axis dimension to the minor axis dimension, a rectangular shape or a round shape. The speaker magnetic circuit 10 may be a magnetic circuit having a different size corresponding to the voice coil 4 having another shape.

  In addition, the electrodynamic speaker 1b includes a connection reinforcing member 8 that connects the rear central portion 2d of the speaker diaphragm 2 and the inner flat portion 5d of the damper 5 in the same manner as the electrodynamic speaker 1a of the previous embodiment. Furthermore, you may provide. An electrodynamic speaker 1b that is stable in operation and hardly generates abnormal noise is realized.

  The inner flat portion 5d of the damper 5 is not limited to the elongated strip shape as described above as long as it does not interfere with the through hole 14 of the speaker magnetic circuit 10, and may have a rib or the like. . Since the inner flat part 5d of the damper 5 connects the two inner fixing parts 5a along the major axis direction, the shape of the two movable parts 5c is hardly deformed in the process of handling the damper 5, and the manufacturing process is stabilized. There are advantages.

  The electrodynamic speaker of the present invention can be applied not only as a speaker built in video / audio equipment such as a display but also to a game machine having a cabinet with a built-in speaker for reproducing sound, a game machine such as a slot machine, etc. It is. In addition, the electrodynamic speaker provided with the magnetic circuit for a speaker according to the present invention has a narrow overall width and can realize a speaker system that reproduces sound in a small and thin cabinet. Suitable.

It is a figure explaining the electrodynamic speaker 1 by preferable embodiment of this invention. (Example 1) It is an expanded view explaining the structure of the electrodynamic speaker 1 by preferable embodiment of this invention. (Example 1) It is an enlarged view explaining the structure of the electrodynamic type speaker 1 at the time of removing the speaker diaphragm 2 by preferable embodiment of this invention. (Example 1) It is a perspective view explaining the magnetic circuit 10 which comprises the electrodynamic speaker 1 by preferable embodiment of this invention. (Example 1) It is a perspective view explaining the top plate 11 which comprises the magnetic circuit 10 by preferable embodiment of this invention. (Example 1) It is a top view explaining the magnetic circuit 10, the voice coil 4, and the damper 5 which comprise the electrodynamic speaker 1 by preferable embodiment of this invention. (Example 1) It is an enlarged view of the AO-A 'section along the major axis direction explaining the composition near magnetic circuit 10 of electrodynamic speaker 1 by a desirable embodiment of the present invention. (Example 1) It is a figure explaining the electrodynamic type speaker 1a by other preferable embodiment of this invention. (Example 2) It is a figure explaining the electrodynamic type speaker 1b by other preferable embodiment of this invention. (Example 3) It is a graph showing the sound pressure frequency characteristic of the electrodynamic speaker of this invention, and a harmonic distortion characteristic. (Examples 1 and 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrodynamic type speaker 2 Speaker diaphragm 3 Edge 4 Voice coil 5 Damper 6 Frame 7 Terminal 8 Connection reinforcement member 9 Buffer member 10 Magnetic circuit 11 Top plate 12 Pole 12a, 12b Protrusion part 13a, 13b Magnetic gap 14 Through-hole 15a, 15b Magnet 16a, 16b Internal space

Claims (6)

An annular top plate having two straight portions parallel to the inner peripheral side;
A pole having two protrusions cut and raised from the under plate on the inner peripheral side;
Two rod-like magnets sandwiched between the top plate and the under plate of the pole and magnetized in the same direction,
The two protrusions of the pole are respectively opposed to the two straight portions of the top plate to form two magnetic air gaps disposed between the two bar-shaped magnets;
The two protrusions of the pole form a through hole therebetween, and the top plate, the under plate, and the two bar-shaped magnets form two internal spaces that communicate with the through hole. ,
Magnetic circuit for speakers. A buffer member that is sandwiched between the two protrusions of the pole and is attached to the approximate center of the through hole;
The magnetic circuit for a speaker according to claim 1. The top plate and the pole have an elongated shape having a major axis direction and a minor axis direction, the two magnetic gaps are provided along the major axis direction, and the two internal spaces are in the major axis direction. Are arranged with the through hole in between,
The speaker magnetic circuit according to claim 1 or 2. The speaker magnetic circuit according to claim 3;
A frame connected to the speaker magnetic circuit;
An edge whose outer peripheral end is fixed to the frame;
A speaker diaphragm whose outer edge is supported by the edge;
A bobbin that includes two straight portions along the major axis direction, one end of which is connected to the center of the speaker diaphragm;
A coil wound around the bobbin and having straight portions disposed in the two magnetic gaps,
Two inner fixed parts to which the other end of the bobbin is connected, an outer fixed part fixed to the top plate of the magnetic circuit for the speaker, and two movable parts to connect the inner fixed part and the outer fixed part And a damper having an inner flat part that connects the two inner fixing parts,
The two movable parts of the damper are respectively disposed in the internal space of the magnetic circuit for the speaker, and the inner flat part of the damper is configured so that the two inner fixed parts extend along the major axis direction. Connecting across the through hole of the speaker magnetic circuit,
Electrodynamic type speaker. The electrodynamic speaker according to claim 4,
A connection reinforcing member for connecting the back center portion of the speaker diaphragm and the inner flat portion of the damper;
Electrodynamic type speaker. The electrodynamic speaker according to claim 4 or 5, comprising the buffer member.
The inner flat portion of the damper is connected to the buffer member;
Electrodynamic type speaker.