JP2009060571A - Speaker diaphragm and electrodynamic type loudspeaker using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker diaphragm and electrodynamic loudspeaker of an elongated shape being shorter in the minor-axis direction than in the major-axis direction, which is excellent in sound reproduction capability with a high efficiency and is not significantly influenced by divided vibrations of an elongated loudspeaker diaphragm, and which is suitably installed in a device such as a display device. <P>SOLUTION: In the elongated speaker diaphragm, the diaphragm body has: a first diaphragm portion including a junction to a voice coil bobbin in a central portion of a rear surface thereof; a second diaphragm portion extending on both sides of the first diaphragm portion in the major-axis direction; and a reinforcement rib extending continuously through the first diaphragm portion and the second diaphragm portion. The edge includes: a free edge portion for freely supporting ends in the minor-axis direction of the first diaphragm portion and the second diaphragm portion; and a fixed edge portion being thicker than the free edge portion for fixedly supporting one end of the second diaphragm portion in the major-axis direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an elongate (rectangular, oval (including elliptical, track-shaped)) electrodynamic speaker having a shorter minor axis direction than the major axis direction, and has an excellent sound reproduction capability and an elongated speaker. The present invention relates to a speaker diaphragm and an electrodynamic speaker suitable for being attached to a device such as a display with little influence even if the diaphragm is divided and vibrated.

  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, slender (rectangular, oval (including elliptical, track-shaped)) electrodynamic speakers have a diaphragm area limited in the minor axis direction, and are affected by the division vibration that is typical of slender speaker diaphragms. It is difficult to obtain a large and flat reproduction sound pressure frequency characteristic, and if the resin material foamed to achieve both the rigidity and light weight of the speaker diaphragm is adopted, the high frequency limit of reproduction cannot be increased. For this reason, there is a disadvantage in sound reproduction ability. Therefore, conventionally, various speaker diaphragms, speaker magnetic circuits, and electrodynamic speakers using the same have been proposed in order to solve these problems.

  For example, the rectangular plane diaphragm has a voice coil bobbin that is in contact with two nodes in different vibration modes among the free vibration modes of the rectangular plane diaphragm, and the rectangular plane is provided by the voice coil that is provided on this bobbin and moves in a piston within the gap of the magnetic circuit. The configuration is such that the diaphragm is attached and driven, and the outer periphery of the rectangular flat diaphragm is asymmetrical on the short side far from the voice coil drive compared to the short side near the voice coil drive. There is an electrodynamic speaker configured to be supported on a frame by a simple edge member (Patent Document 1).

  In addition, the speaker is equipped with a rectangular flat diaphragm made of foamable resin, and the long peripheral edge of the flat diaphragm is fixed to the frame and the short peripheral edge is a free edge to stabilize the operation and stabilize the operation. There is a speaker (Patent Document 2). In addition, a substantially arc-shaped elastic resin is superimposed on the corner formed by the frame of the edge and heat-molded, and an elastic resin layer is provided in the vicinity of the corner where the edge is likely to be deformed when the speaker is driven. Some of them attempt to absorb and relax distortions caused by deformation and the like to prevent deterioration of sound quality due to these (Patent Document 3).

  Conventionally, there is a speaker diaphragm in which a film foam having thermoplasticity and a lightweight and rigid body are bonded to each other and a vibration substrate is not used at an edge portion (Patent Document 4). In addition, a laminated plate obtained by laminating a thermoplastic resin film on one side or both sides of a non-foamed thermally foamable resin sheet is obtained and heat-treated in a vibration plate-shaped mold, and the thermoplastic resin film is plasticized. There is a speaker diaphragm in which a laminated plate is formed into a diaphragm shape by foaming a thermally foamable resin sheet, and a thermoplastic resin film extending around is formed as an edge (Patent Document 5).

  Further, in the speaker diaphragm by the applicant of the present invention, an edge joint portion joined to the edge on the outer peripheral side of the diaphragm, and a diaphragm portion provided on the inner peripheral side of the edge joint portion and joined to the voice coil, The diaphragm portion has a virtual reference plane defined as a plane including the edge joint, and a plurality of nodal lines defined as lines intersecting the virtual reference plane and a distance from the virtual reference plane are maximized. With a plurality of ridges defined as lines connecting the points, where the plurality of nodal lines do not intersect the major axis of the diaphragm non-parallel and intersect the minor axis of the diaphragm (Patent Document 6). By using the speaker diaphragm in such a waveform shape, the strength of the elongated diaphragm in the longitudinal direction, that is, the major axis direction is improved, and the resonance frequency at which split resonance occurs in the major axis direction can be shifted to a higher frequency. . Furthermore, since the interval between the corrugations in the short axis direction gradually changes as it goes in the long axis direction, it is possible to disperse the resonance frequency of the split resonance that tends to occur in the long axis direction. As a result, if an elongated diaphragm having this waveform shape is used, a speaker with less peak dip in sound pressure frequency characteristics and excellent reproduction sound quality can be realized.

JP-A-58-92198 Japanese Utility Model Publication No. 40-32164 Japanese Patent Laid-Open No. 2001-28591 Japanese Utility Model Publication No. 50-61834 JP-A-57-132500 JP 2007-180910 A

  In an acoustic device such as a display, for good sound reproduction, it is preferable that an electrodynamic speaker having a good reproduction sound quality comparable to that of Patent Document 6 can be attached to the inside. However, when a speaker diaphragm formed from a resin foam is used to reduce the weight of the speaker diaphragm for the purpose of improving the reproduction sound pressure level, the influence of divided vibration in the major axis direction is significant. Thus, various problems may occur, such as difficulty in obtaining a flat reproduction sound pressure frequency characteristic and an inability to increase the high-frequency reproduction limit frequency. In addition, when the end portion of the speaker diaphragm is fixed and supported, there is a problem that the symmetry of the front-rear amplitude is poor and the distortion characteristic is deteriorated. In addition, before and after the amplitude of the front and rear, when the diaphragm of the speaker vibrates, the side on which the voice coil, the damper, and the magnetic circuit are attached is the rear side, and the side on which the diaphragm is exposed is the front side.

  The present invention has been made in order to solve the above-described problems of the prior art, and the object of the present invention is to provide an elongated shape (rectangle, oval (elliptical shape, track shape) having a shorter minor axis direction than the major axis direction. Including)), which is highly efficient and excellent in sound reproduction capability, has little effect even when the elongated speaker diaphragm splits and vibrates, has good front-rear amplitude symmetry and low distortion, displays, etc. It is an object of the present invention to provide a speaker diaphragm and an electrodynamic speaker that are suitable for being attached to other devices.

  A speaker diaphragm according to the present invention is a speaker diaphragm including an elongated diaphragm body having a major axis direction and a minor axis direction, and an edge that supports an outer peripheral edge of the diaphragm body. A first diaphragm portion including a joint portion with a voice coil bobbin at the center on the back side, a second diaphragm portion extending on both ends in the major axis direction of the first diaphragm portion, and a first diaphragm And reinforcing ribs formed continuously over the respective second diaphragm parts, and the edges are the end parts of the first diaphragm part and the second diaphragm part in the minor axis direction. A free edge portion that is freely supported, and a fixed edge portion that is thicker than the free edge portion and that fixes and supports one end of the second diaphragm portion in the major axis direction.

  Preferably, in the speaker diaphragm of the present invention, the first diaphragm portion of the diaphragm main body has a surface area whose area is larger than the projected sectional area of the voice coil bobbin, and defines the average thickness of the first diaphragm portion. The first average thickness value is configured to be smaller than the second average thickness value that defines the average thickness of the second diaphragm portion.

  Preferably, in the speaker diaphragm of the present invention, reinforcing ribs are formed at both long-diameter end ribs formed at both ends in the short-diameter direction of the diaphragm main body and at the central portion in the short-diameter direction of the diaphragm main body. A long-diameter central rib, and a short-diameter both-end rib formed at one end in the long-diameter direction of the second diaphragm portion. Do not connect with.

  Preferably, in the speaker diaphragm of the present invention, the long-diameter central rib of the reinforcing rib is composed of two separated long-diameter central first ribs and long-diameter central second ribs arranged with the joint portion with the voice coil bobbin interposed therebetween. The long-diameter central rib height that defines the rib heights of the long-diameter central first rib and the long-diameter central second rib is the highest in the first diaphragm portion, and is at one end portion in the long-diameter direction in the second diaphragm portion. It gets lower as it goes.

  The speaker diaphragm of the present invention includes a thermoplastic resin foam sheet in which the diaphragm main body is extruded and laminated on the surface with a thermoplastic resin film, and the diaphragm main body, the free edge portion, and the fixed edge portion include The integrally molded edge is bonded with an adhesive.

  Further, the speaker diaphragm of the present invention includes a thermoplastic resin foam sheet in which a diaphragm body is extruded and laminated on a front surface and a back surface with a thermoplastic resin film, and edges are formed from the front surface and the back surface of the diaphragm body. A diaphragm body including an extended thermoplastic resin film, a diaphragm main body and an edge, and a reinforcing body formed of a thermoplastic resin foam sheet having a front surface and a back surface laminated with a thermoplastic resin film and supporting an outer peripheral edge of the edge. , It is configured integrally.

  Further preferably, in the speaker diaphragm of the present invention, the free edge portion of the edge includes a first free edge portion that freely supports an end portion in the minor axis direction of the first diaphragm portion, and a short portion of the second diaphragm portion. A second free edge portion that freely supports the radial end portion, and the stiffness k1 of the first free edge portion is configured to be smaller than the stiffness k2 of the second free edge portion.

  The electrodynamic speaker of the present invention is wound around a speaker diaphragm of the present invention, a frame to which the outer peripheral end side of the edge is fixed, a magnetic circuit fixed to the frame and having a magnetic gap, and a voice coil bobbin. A voice coil; and a damper that arranges the voice coil in the magnetic gap.

  The operation of the present invention will be described below.

  The speaker diaphragm of the present invention has an elongated (rectangular, oval (including elliptical, track-shaped)) diaphragm body having a major axis direction and a minor axis direction, and an edge that supports the outer peripheral edge of the diaphragm body. And a speaker diaphragm. The diaphragm main body is a thermoplastic resin foam sheet (typically, the thickness of the thermoplastic resin foam contained is unevenly formed by using a vacuum forming method in combination with plug assist molding. A foamed polystyrene sheet) is laminated on the surface with a thermoplastic resin film. Moreover, the thermoplastic resin film (or sheet) on which the diaphragm main body is laminated is typically a polystyrene resin film or a polyurethane elastomer resin film. Therefore, the speaker diaphragm of the present invention is formed by forming a diaphragm main body into an elongated shape by heating and softening a foamed thermoplastic resin sheet laminated on the surface in advance and then cooling it with a die press. By adhering an edge made of foamable rubber or the like around the surface, or by integrally forming the edge with a thermoplastic resin film having a laminated surface, it can be formed into an arbitrary elongated shape. In addition, the speaker diaphragm of the present invention can include a frame, a magnetic circuit, a voice coil wound around a voice coil bobbin, and a damper, thereby providing an elongated electrodynamic speaker. 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 diaphragm main body of the speaker diaphragm of the present invention is extended to both the first diaphragm part including a joint part with the voice coil bobbin at the center part on the back side, and both ends in the major axis direction of the first diaphragm part. It has a 2nd diaphragm part, a 1st diaphragm part, and the reinforcement rib formed continuously over each 2nd diaphragm part. The diaphragm main body is formed in an elongated shape including a rectangular shape, an oval shape, an elliptical shape, and a track shape, and connects the first diaphragm portion and the second diaphragm portions extended to both ends thereof. Since the reinforcing rib is provided, it is possible to suppress the split vibration of the reinforcing rib in the major axis direction and realize a flat reproduction sound pressure frequency characteristic with less peak dip.

  The first diaphragm portion is a portion to which a cylindrical voice coil bobbin is attached at the central portion on the back side of the speaker diaphragm. The first diaphragm portion includes the projected cross-sectional area of the voice coil bobbin and includes two long sides of the elongated speaker diaphragm. And a substantially rectangular region defined by two imaginary lines that cross between the long sides in the minor axis direction. Further, the second diaphragm portion is an area extending from these imaginary lines of the first diaphragm portion to both ends on the opposite side to the voice coil bobbin in the major axis direction (that is, the outer side in the major axis direction). is there. In addition, the reinforcing rib is a protruding structure that forms a ridge line or a valley line when viewed from the front side of the speaker diaphragm, a long-diameter both-end rib formed in the short-diameter direction, and a long-diameter central rib Furthermore, you may have the short diameter both-ends rib formed in one edge part of the major axis direction of the 2nd diaphragm part.

  For example, the long central rib of the reinforcing rib may be a rib that is continuously formed so as to cross one second diaphragm part, the first diaphragm part, and the other second diaphragm part. Also, it consists of two separate long-diameter central first ribs and long-diameter central second ribs arranged across the joint with the voice coil bobbin, and the long-diameter central rib heights defining these rib heights are respectively It may be the highest in the first diaphragm and lower as it goes to one end in the major axis direction in the second diaphragm. The reinforcing ribs including the long-diameter central rib enable the middle diaphragm to be reproduced by the first diaphragm as will be described later, while increasing the rigidity in the long-diameter direction of the elongated speaker diaphragm, while increasing the longitudinal amplitude. The symmetry of can be ensured.

  On the other hand, the edge formed with non-uniform thickness is formed with a free edge portion that freely supports the short-diameter end of the first diaphragm portion and the second diaphragm portion, and a thicker thickness than the free edge portion. And a fixed edge portion that fixes and supports one end of the second diaphragm portion in the major axis direction. That is, in the diaphragm main body of the present invention, the end portion in the short diameter direction (the portion corresponding to the long side of the diaphragm main body) is freely supported by the free edge portion of the edge, and the end portion in the long diameter direction is supported by the fixed edge portion of the edge. (A portion corresponding to the short side of the diaphragm main body) is fixedly supported. Therefore, in the case of a slender speaker diaphragm whose major axis is significantly longer than the minor axis, when the voice coil is greatly displaced at a frequency near or below the lowest resonance frequency f0, the end in the major axis direction is Because it is fixedly supported and becomes a node and vibrates in the lowest bending vibration mode that drives the central part in the major axis direction and becomes a belly, it suppresses the dip that tends to appear first in the low frequency range, and flat playback sound Pressure frequency characteristics can be realized. Furthermore, the rigidity of the reinforcing ribs can improve the symmetry of the front-rear amplitude of the speaker diaphragm, so that an electrodynamic speaker with less distortion and excellent reproduction sound quality is realized.

  The first diaphragm portion of the diaphragm main body has a surface area having an area larger than the projected cross-sectional area of the voice coil bobbin, and the first average thickness value defining the average thickness of the first diaphragm portion is the first It is comprised so that a value may become smaller than the 2nd average thickness value which prescribes | regulates the average thickness of 2 diaphragm parts. Accordingly, since the average thickness of the first diaphragm part to which the voice coil bobbin is attached is thin, the equivalent mass around the voice coil bobbin that contributes to emitting sound waves in the mid-high range is reduced, and the voice coil As a result of efficiently transmitting the driving force generated in step 1, the reproduced sound pressure level in the mid-high range can be increased. Note that the free edge portion of the edge is a first free edge portion that freely supports the end portion in the minor axis direction of the first diaphragm portion and the second free end portion that supports the end portion in the minor axis direction of the second diaphragm portion. By configuring the material or the shape so that the stiffness k1 of the first free edge portion is smaller than the stiffness k2 of the second free edge portion. The amplitude range of the first diaphragm can be expanded, and the reproduction sound pressure level can be further increased, improving the efficiency.

  The diaphragm body is not limited to an extruded polystyrene foam sheet as long as it is a thermoplastic resin containing polystyrene foam, but is selected from polystyrene, acrylic, polyethylene, polypropylene, polycarbonate, ABS resin, and the like. One type or a plurality of blended resin foams may be used. Further, the edge bonded to the diaphragm main body is made of an elastomer material, and may be any material that has a non-uniform thickness and can form a free edge portion and a fixed edge portion. Besides the foamable rubber or the thermoplastic resin film, a foamed urethane sheet may be formed by heat molding, or a rubber edge having a thickness changed by injection molding or the like may be used. When the edge of the speaker diaphragm is a laminate of the front and back surfaces of the diaphragm main body and includes a thermoplastic resin film extending around the diaphragm main body, the diaphragm main body, the edge, and the edge Since the reinforcement body that reinforces the outer peripheral edge of the unit is configured integrally, it is possible to reduce the number of steps and man-hours for creating a diaphragm body consisting of the diaphragm body, edge and reinforcement body, and reduce the cost of electrodynamic speakers Can be achieved.

  Even if it is an elongated speaker diaphragm with a shorter minor axis direction than the major axis direction, it has high efficiency and excellent sound reproduction ability, less influence of divided vibration, good symmetry in front and rear amplitude, less distortion, display etc. It is possible to provide an electrodynamic speaker that is suitable for being attached to other devices.

  Even if the speaker diaphragm of the present invention is an elongated speaker diaphragm having a shorter minor axis direction than the major axis direction, the efficiency is high and the sound reproduction ability is excellent. For the purpose of providing an electrodynamic speaker that is suitable for mounting on devices such as displays that have good distortion and low distortion, the diaphragm main body, which is formed from foamed thermoplastic resin and has a non-uniform thickness, is centered on the back side. A first diaphragm part including a joint part with a voice coil bobbin in the part, a second diaphragm part extending on both ends in the major axis direction of the first diaphragm part, a first diaphragm part, and Reinforcing ribs that are continuously formed over the second diaphragm portion, and an edge having a non-uniform thickness is provided between the first diaphragm portion and the end portion in the minor axis direction of the second diaphragm portion. Free edge part to support freely and free edge part A second diaphragm portion fixing edge portion of one end of the major axis to the fixed support of Rimoatsumi is the thick, by to have, was realized.

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

1 and 2 are diagrams illustrating an electrodynamic speaker 1 according to a preferred embodiment of the present invention. FIG. 1 (a) is a perspective view of the electrodynamic speaker 1 as viewed from the front side obliquely upward, and FIG. 1 (b) is a perspective view of the electrodynamic speaker 1 as viewed from the diagonally lower side of the back side. 2A is an OA cross-sectional view of the electrodynamic speaker 1, and FIG. 2B is a BB ′ cross-sectional view of the electrodynamic speaker 1. 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 connecting the points AA ′ extends is the major axis direction, and the point BB ′.
The direction in which the straight line 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 210 mm and a minor axis direction length L2 of about 35 mm. Even if it is, it is a speaker which has a diaphragm area equivalent to a circular diaphragm with a diameter of about 90 mm. 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 (a front damper 5a and a rear damper 5b) so as to vibrate. The frame 6 has an elongated shape corresponding to the track-shaped speaker diaphragm 2, and the magnetic circuit 10 fixed to the frame 6 also has an elongated shape having a narrow width not more than the length L2 in the minor axis direction. 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.

  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 this example, the extruded thermoplastic resin foam sheet (specifically, polystyrene paper) is used with a vacuum forming method in combination with plug assist molding, so that the thickness is non-uniform and ribs are provided. A speaker diaphragm 2 is obtained. That is, the elongated speaker diaphragm 2 in which the major axis direction length L1 and the minor axis direction length L2 are significantly different from each other tends to be noticeable due to the divisional vibration in the major axis direction. The radial cross-sectional shape is substantially W-shaped, and the shape has rigidity in the long-diameter direction. In addition, a thermoplastic resin film (specifically, a polystyrene film) is thermally bonded to the front and back surfaces of the speaker diaphragm 2 to increase the rigidity of the speaker diaphragm 2.

  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 flexibility of the polystyrene paper that forms the speaker diaphragm 2 in the major axis direction, Bending vibration is made possible.

  The voice coil 4 is formed of a bobbin 4a formed in a cylindrical shape, and a coil 4b wound around one end thereof and supplied with an audio 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. The coil 4b is disposed in a circular magnetic gap 12 of the magnetic circuit 10 described later. Note that the tinsel wire 8 solders the terminal 7 fixed to the frame 6 and the lead wire of the coil 4b from the terminal 7 so as to conduct the current, and supplies an audio current to the coil 4b. However, the tinsel wire 8 may be electrically connected to the terminal 7 by providing a metal eyelet on the speaker diaphragm 2.

  The damper 5 is a two-stage damper composed of a front damper 5a and a rear damper 5b, and is formed by cutting a circular corrugation damper formed by impregnating a phenolic resin with a flexible woven fabric as a base material, and having an elongated shape (Track type). The inner peripheral ends of the front damper 5a and the rear damper 5b are connected to the cylindrical outer surface side of the bobbin 4a to support the rear center side of the speaker diaphragm 2. The outer peripheral end sides of the front damper 5 a and the rear damper 5 b are fixed to the fixing portion of the frame 6. The damper 5 is a corrugation damper having another shape, and may not be formed of two stages, or may be formed of another material, and connects the inner ring and the outer ring. A butterfly damper having an arm and formed of metal or resin may be used.

  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, a substantially rectangular fixing portion that fixes the edge 3, dampers 5 a and 5 b, and a magnetic circuit 10 is provided with a fixing portion for fixing 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. 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 able to vibrate with respect to the frame 6.

  The magnetic circuit 10 includes an elongated top plate 11 that is fixed to the frame 6, a center pole 12 that is cylindrical and is inserted into a circular hole formed in the center of the top plate 11, and an elongated under plate 14. And two main magnets 15a and 15b magnetized in the same direction. The top plate 11 and the center pole 12 form a circular magnetic air gap 13 having a uniform width in the radial direction. The main magnets 15a and 15b are sandwiched between the top plate 11 and the under plate 14, and are symmetrically arranged in the major axis direction with the center pole 12 in the middle.

  The two main magnets 15a and 15b are Nd—Fe—B rare earth magnets having a strong coercive force even in a small volume, and each has a substantially cylindrical shape. 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, and has a residual magnetization and a retention value. A magnet with a large magnetic force. Since the rare earth magnet has a large coercive force, it can generate a high magnetic flux density, but has a large permeance coefficient and is difficult to demagnetize.

  While the two main magnets 15a and 15b are arranged in the major axis direction of the magnetic circuit 10 of the present embodiment, no magnet (magnet) that generates a magnetic force is arranged in the minor axis direction. 10 is an elongated shape, and when the magnetic circuit 10 is viewed from the side of the minor axis direction, the opening angle is wide enough that the cylindrical side surface of the center pole 12 can be directly viewed from the open space where no magnet is arranged. It has become.

  The magnetic circuit 10 is an outer 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 main magnets 15a and 15b having strong magnetomotive force are arranged in the major axis direction. Therefore, 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. Therefore, including the use of the lightweight speaker diaphragm 2, the highly efficient electrodynamic speaker 1 is realized.

  When an audio current is supplied to the coil 4b of the voice coil 4, a driving force is applied to the voice coil 4 disposed in the magnetic gap 13, and the voice coil 4 vibrates in the vertical direction in FIG. The diaphragm 2 also vibrates 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 polystyrene paper forming the speaker diaphragm 2, and when the voice coil 4 is greatly displaced at a frequency near or below the lowest resonance frequency f0, the major axis direction The both ends of the speaker diaphragm 2 are bent in a bow shape in the major axis direction and deformed.

  Further, even if the circular magnetic air gap 13 has a uniform width in the radial direction, the magnetic circuit 10 has different magnetic flux density distributions in the major axis direction and the minor axis direction, and has substantially cylindrical main magnets 15a and 15b and a circular shape. An extremely strong magnetic flux density is generated in the major axis direction where the magnetic gap 13 is closest, and the magnetic flux density in the major axis direction is higher than the magnetic flux density in the minor axis direction. Since the magnetic flux density distribution in the circumferential direction in the circular magnetic gap 13 is different between the major axis direction and the minor axis direction, the driving force for driving the speaker diaphragm 2 can be different between the major axis direction and the minor axis direction, and the reproduction frequency The peak dip of characteristics can be reduced.

3 and 4 are diagrams for explaining the speaker diaphragm 2 and the edge 3. FIG. 3A is a perspective view of the speaker diaphragm 2 and the edge 3 as viewed from diagonally upward on the front side, and FIG. 3B is a perspective view of the speaker diaphragm 2 and the edge 3 viewed from diagonally below on the back side. FIG. 4A is a sectional view taken along the line OA ′ of the speaker diaphragm 2 and the edge 3. FIG. 4B is a sectional view taken along the line BB ′ of the speaker diaphragm 2 and the edge 3. FIG. (C) is CC 'sectional drawing of the speaker diaphragm 2 and the edge 3. FIG. As will be described later, a part of the structure of the speaker diaphragm 2 and the edge 3, a cross-sectional structure, and the like are omitted. Further, the direction in which the straight line connecting the points AA ′ extends is the major axis direction, and the point BB ′.
The direction in which the straight line connecting the two extends is the minor axis direction.

  The speaker diaphragm 2 of the present embodiment is formed by extruding polystyrene paper (PSP) so as to have a non-uniform thickness and ribs by using a vacuum forming method combined with plug assist molding. A polyurethane elastomer film is heat-sealed on the back surface to increase its rigidity. Specifically, the speaker diaphragm 2 uses a 10-fold expanded extruded polystyrene sheet (thickness of about 2.0 mm) blended with 10% acrylic as a raw material, and a polystyrene film (thickness of about 50 μm) on both sides. It is heat-sealed and laminated, and a diaphragm is formed by a vacuum forming method combined with plug-assist forming. Rigidity and loss can be improved by laminating a polystyrene film on one or both sides as compared with the case where the speaker diaphragm is formed only by the extruded polystyrene foam sheet. For example, the physical properties of the speaker diaphragm are Young's modulus: 4.6E + 8 (dyne / Cm2), density: 0.043 (g / Cm3), and tan δ: 0.043 when only PSP is used. When a polystyrene film is laminated on both sides of the PSP, Young's modulus: 9.7E + 8 (dyne / Cm2), density: 0.055 (g / Cm3), and tan δ: 0.074 can be improved.

  As for the outline outline dimensions of the track-shaped speaker diaphragm 2, the major axis direction length L1 is about 198 mm and the minor axis direction length L2 is about 23.4 mm. The speaker diaphragm 2 varies in thickness within a range of about 1 mm to about 3 mm by vacuum forming, and the thickness can be made non-uniform according to the rigidity required for the speaker diaphragm. The speaker diaphragm 2 has ribs extending in the major axis direction and has a substantially W-shaped cross section in the minor axis direction. For example, the long-diameter end ribs forming the outermost periphery of the speaker diaphragm 2 have a thickness of about 1 mm.

  Note that the vacuum forming using plug assist molding is a molding method in which a laminated material is preheated and softened, and then pressed with a convex mold while sucking with a desired concave mold. The polystyrene paper of this example may be a foamed sheet made of other thermoplastic resin, and the thermoplastic foamed sheet is obtained by an extrusion foaming method or a bead foaming method. The thermoplastic resin constituting the foam sheet is made of one resin selected from polystyrene, acrylic, polyethylene, polypropylene, polycarbonate, ABS resin, vinyl chloride resin, vinyl acetate, vinyl acetate-ethylene resin, or a plurality of selected resins. Any resin obtained by blending may be used.

  The resin constituting the thermoplastic resin film to be laminated is one selected from polystyrene, acrylic, polyethylene, polypropylene, polyurethane, polyethylene terephthalate, polyethylene naphthalate, nylon, or polyurethane elastomer, polyolefin elastomer, polyamide elastomer, and the like. Or a resin obtained by blending a plurality of selected resins. In this example, in the double-sided laminate of the front and back surfaces, both surfaces are the same thermoplastic resin film, but the front and back surfaces may be different thermoplastic resin films. In addition, the laminate may be heat-sealed due to the thermoplasticity of the thermoplastic foam sheet and the thermoplastic resin film, or may be a thermoplastic adhesive printed or applied to the thermoplastic resin film. It may be heat-sealed.

  The first diaphragm 21 of the speaker diaphragm 2 crosses two long sides of the elongated speaker diaphragm 2 in the center of the back side of the speaker diaphragm 2 and the longer side in the minor axis direction. This is a substantially rectangular region defined by two virtual lines X and X ′. In the case of the present embodiment, the distance between the imaginary lines X and X ′ is about 40 mm, which is larger than the diameter of the voice coil bobbin 4 and can be set within a range of about ½ or less of the longitudinal length L1 of the speaker diaphragm. It is. As shown in FIG. 4B, the first diaphragm portion 21 includes a circular flat portion 23 to which one end of the substantially cylindrical voice coil bobbin 4 is attached at the center on the back side. Is domed. Moreover, the outer side of the circular flat part 23 is a substantially cone shape which has a standing | starting-up, and has a shape connected to the 2nd diaphragm part 22 mentioned later. The first diaphragm portion 21 that contributes to the reproduction of the middle sound range and the high sound region is formed with a thickness of the diaphragm thinner than that of the second diaphragm portion 22, and the first average that defines the average thickness of the first diaphragm portion 21. The thickness value t1 is about 2 mm.

  The second diaphragm 22 has two long sides of the elongated speaker diaphragm 2, a short side of the elongated speaker diaphragm 2, and the above-described virtual side on both ends of the elongated speaker diaphragm 2. This is an area defined by the line X (or X ′). The short side portion of the track-shaped speaker diaphragm 2 of the present embodiment includes a semicircular portion that defines the track shape, and the cross-sectional shape of the second diaphragm portion 22 in the minor axis direction is shown in FIG. As shown, it is substantially W-shaped and has a substantially constant cross-sectional shape except for the semicircular portion corresponding to the short side. In the case of the present embodiment, the second average thickness value t2 that defines the average thickness of the second diaphragm portion is about 3 mm, and the diaphragm is formed thicker than the first diaphragm portion 21.

  The reinforcing rib of the speaker diaphragm 2 has a protruding structure that forms a ridge line or a valley line when viewed from the front side of the speaker diaphragm 2. Specifically, in the case of the present embodiment, the long-diameter central rib 24 and the two long-diameter both-end ribs 25 formed at both ends in the short-diameter direction of the speaker diaphragm 2 are the first diaphragm 21, And it forms continuously over each 2nd diaphragm part 22. FIG. That is, the long-diameter central rib 24 and the long-diameter both-end ribs 25 penetrate the portion corresponding to the three upper end points of the substantially W shape in the cross-sectional shape of the speaker diaphragm 2 in the long-diameter direction. Improve the rigidity. Furthermore, the short-diameter both-end ribs 26 formed in an arc shape corresponding to the semicircular shape of the second diaphragm portion 22 connect the respective long-diameter both-end ribs 25, so that the track-shaped speaker diaphragm 2 Reinforce the outer periphery to increase rigidity. In addition, since the ridge line of the protrusion of the long-diameter central rib 24 does not reach both ends in the long-diameter direction of the track-type speaker diaphragm 2, the long-diameter central rib 24 and the short-diameter both-end ribs 26 are not connected. Since the first diaphragm portion 21 and the second diaphragm portion 22 are reinforced so as to be connected, the track-shaped speaker diaphragm 2 is reinforced to increase rigidity.

  On the other hand, the edge 3 has a track shape with a cut inner diameter of about 195 mm × about 21 mm and a semicircular arc-shaped radius of about 10.5 mm. In this embodiment, flexible foam rubber is injected into the mold. Then, by heating and foaming, not only the movable part of the edge but also the reinforcing body 34 at the outer peripheral end fixed to the fixed part of the frame 6 is integrally formed. In this embodiment, the speaker diaphragm 2 and the edge 3 are attached by applying a heat-bonding adhesive to the outer peripheral portion of the speaker diaphragm 2 and drying it, followed by hot pressing with an attaching mold. In addition, it is possible to obtain a diaphragm complete product in which the reinforcing body 34 is also integrally formed.

  Specifically, the edge 3 is a free edge portion (first diaphragm portion 21) that freely supports both ends in the minor axis direction of the speaker diaphragm 2 on the long side of the track shape extending linearly in the major axis direction of the speaker diaphragm 2. And the second free edge portion 32 corresponding to the second diaphragm portion 22), and the speaker diaphragm 2 is fixed on the track-shaped short side that is arcuate. And a fixed edge portion 33 to be supported. As shown in FIG. 4B and FIG. 4C, the first free edge portion 31 and the second free edge portion 32 are free edges having a single inverted V-shaped roll having mobility. The thickness of the foam rubber is about 0.2 mm.

  Further, as shown in FIG. 4A, the fixed edge portion 33 is a fixed edge formed from a gasket-like reinforcing body 34 without a roll-like movable portion, and has a thick wall. The connected outer peripheral side is fixed to the fixed part of the frame 6 and the inner peripheral side is fixed to the second diaphragm part 22, and supports both ends of the short side of the track shape of the speaker diaphragm 2 so as not to freely vibrate. That is, the fixed edge portion 33 has a shape in which the portion corresponding to the movable portion including the inverted V-shaped portion of the first free edge portion 31 and the second free edge portion 32 is filled with foamed rubber so as not to freely vibrate. Thus, the thickness of the foam rubber is about 2 mm to about 3.5 mm. As a result, the fixed edge portion 33 restrains both ends of the speaker diaphragm 2 in the major axis direction. Note that the fixed edge portion 33 does not have to be thickened in all of the track-shaped short-side arcs, and part of the track-shaped short-side arcs are fixed edges, and the other portions of the arcs. May become a free edge and intermittently connect to the free edge.

  Therefore, the electrodynamic speaker 1 having the elongated speaker diaphragm 2 and the edge 3 according to the present embodiment is flexibly supported by the compliance of the free edge portion of the edge 3 in the short diameter direction, while the speaker in the long diameter direction. Bending vibration is caused by the flexibility of the foamed sheet of thermoplastic resin forming the diaphragm 2. As a result, as described later, a dip that tends to appear first in the low sound range can be suppressed, and a flat reproduction sound pressure frequency characteristic can be realized. Furthermore, as will be described later, the rigidity of the reinforcing ribs can improve the symmetry of the front-rear amplitude of the speaker diaphragm, so that an electrodynamic speaker with less distortion and excellent reproduction sound quality is realized. Further, since the average thickness t1 of the first diaphragm portion 21 is formed thinner than the thickness t2 of the diaphragm of the second diaphragm portion 22, the reproduction efficiency in the midrange and the high range is improved and the reproduction band is wide. An electrodynamic speaker is realized.

  FIG. 5 is a graph for explaining the operation of the electrodynamic speaker 1 having the elongated speaker diaphragm 2 and the edge 3 according to the present embodiment, and FIG. 5A illustrates the reproduction sound pressure frequency characteristic of the embodiment. FIG. 5B is a graph for explaining the reproduction sound pressure frequency characteristics of the conventional electrodynamic speaker of the comparative example. FIG. 6 is a graph showing the displacement amount of the front-rear amplitude when a driving force is applied to the voice coil 4 including the speaker diaphragm 2 in the electrodynamic speaker 1, and the absolute value of the value in the front-rear direction is shown. Thus, the characteristic curve of the graph is folded, and when the front-rear symmetry is good, the forward displacement curve and the backward displacement curve are displayed so as to overlap. The electrodynamic speaker of the comparative example is an elongated speaker diaphragm (not shown) formed of the same materials and parts as those of the embodiment. The difference from the embodiment is that the speaker diaphragm is in the center of the major axis. This is a boat-like shape that does not have the ribs 24, and has a free edge portion that freely supports the speaker diaphragm on the short side of the track shape that has an arc shape.

  As shown in FIGS. 5 (a) and 5 (b), the electrodynamic speaker 1 including the elongated speaker diaphragm 2 and the edge 3 according to the present embodiment has a frequency of about 120 Hz to that seen in the comparative example. A wide range of dip around 240 Hz and a dip of about 1.5 kHz disappear, and a relatively flat frequency characteristic can be realized. In addition, as shown in FIGS. 6 (a) and 6 (b), the electrodynamic speaker 1 according to the present embodiment is improved in the asymmetry of the front-rear amplitude seen in the comparative example. Occurrence of malfunctions such as occurrence of even-order distortion and fluttering sound can be reduced. In the case of the comparative example, which is a boat-shaped diaphragm not having the long-diameter central rib 24, a significant front-rear asymmetry is shown due to lack of rigidity in the long-diameter direction. Symmetry is improved and good audio reproduction is possible.

  In the case of the present embodiment, the weight of the vibration system of the completed diaphragm including the elongated speaker diaphragm 2 and the edge 3 (including the reinforcing body 34) is about 1.56 g (diaphragm body 1. 18 g, diaphragm part adhesive 0.2 g, edge movable part 0.55 g (however, 1/3 of the edge movable part is expected as the vibration system mass). On the other hand, the man-hours required to produce this diaphragm finished product are as follows: speaker diaphragm 2 molding 10 seconds, cutting 5 seconds, edge 3 molding 30 seconds, cutting 15 seconds, adhesive application 10 seconds, bonding 15 A total of 85 seconds.

  Next, the speaker diaphragm 2A (not shown) of the present embodiment will be described. The speaker diaphragm 2A is made of a material in which a thermoplastic foam sheet is used as a core material and a thermoplastic resin film is laminated on the front and back surfaces, and the main body portion of the speaker diaphragm 2A, the edge 3A, and the reinforcing body 34A are simultaneously provided. One-piece molding. The speaker diaphragm 2A has a polyurethane elastomer film thermally bonded to the front and back surfaces of the extruded polystyrene paper. The speaker diaphragm 2A is molded by the vacuum molding method combined with the plug assist molding described above. A diaphragm main body having the same shape as the speaker diaphragm 2 of Example 1 is obtained. However, the edge 3A is integrally formed from a polyurethane elastomer film extending from the front surface and the back surface of the speaker diaphragm 2A to form a free edge at the end portion in the short diameter direction, and the end portion in the long diameter direction The difference is that a fixed edge is formed. Further, the reinforcing body 34A that supports the outer peripheral edge of the edge 3A is integrally formed of polystyrene paper having a polyurethane elastomer film laminated on both surfaces, like the main body portion of the speaker diaphragm 2A.

  Specifically, the diaphragm main body portion of the speaker diaphragm 2A is different from the speaker diaphragm 2 of the previous embodiment in that the laminated thermoplastic resin film is a polyurethane elastomer film (thickness: about 50 μm). Is different. However, the outline dimensions of the track-shaped speaker diaphragm 2 are such that the major axis length L1 is about 198 mm and the minor axis direction length L2 is about 23.4 mm. Since the speaker diaphragm 2A has a thickness in the range of about 0.3 mm to about 3 mm and has the cross-sectional shape and the reinforcing rib described in the speaker diaphragm 2, the electrodynamic speaker 1 described in the first embodiment is used. The parts common to those constituting the above are denoted by the same reference numerals and the description thereof is omitted.

  The edge 3A has a track shape having a cutting inner diameter of about 195 mm × about 21 mm and a semicircular arc radius of about 10.5 mm. In this embodiment, the edge 3A corresponds to the free edge portion (corresponding to the first diaphragm portion 21) of the edge 3A. The first free edge portion 31A and the second free edge portion 32A corresponding to the second diaphragm portion 22 are included in the polyurethane elastomer film extending from the front surface and the rear surface of the speaker diaphragm 2A. Since the thin foamed polystyrene sheet is included and integrally formed, its thickness is about 0.3 mm. Similarly to the speaker diaphragm 2, the fixed edge portion 33A of the edge 3A gradually increases in thickness from about 0.3 mm to 2.5 mm and is continuously formed on the reinforcing body 34A. The reinforcing body 34A is formed into a thick shape and constitutes an arrow paper and a gasket having rigidity utilizing the thickness of the expanded polystyrene sheet to be foamed.

  In the case of this embodiment, the weight of the finished diaphragm including the elongated speaker diaphragm 2A and the edge 3A (including the reinforcing body 34) is about 1.51 g, which is 1 / of the edge movable portion. Assuming 3 as the vibration system mass, the weight of the vibration system is about 1.29 g. Compared to the edge 3 of the previous embodiment, the weight of the vibration system can be reduced by about 17%, and when used for an electrodynamic speaker, the level of reproduced sound pressure can be improved.

  Therefore, even if the edge 3A in this embodiment is formed integrally with the speaker diaphragm 2A, the cross-sectional shape thereof can be made substantially the same as that of the foamed rubber edge in the previous embodiment. In the minor axis direction, flexural vibration is caused by the flexibility of the polystyrene paper forming the speaker diaphragm 2A in the major axis direction while being flexibly supported by the compliance of the free edge portion of the edge 3A. As a result, the electrodynamic speaker employing the speaker diaphragm of the present embodiment can suppress the dip that tends to appear first in the low sound range, and can realize a flat reproduction sound pressure frequency characteristic. There is no variation in the amount of adhesive applied to the speaker diaphragm 2A and the edge 3A, and the bonding between the edge 3A and the reinforcing body 34A, and there is no variation such as misalignment in the bonding process. In addition, since the variation in the amount of adhesive applied to the bonding portion of the bonded portion occurs, as a result, stable quality without variation in the characteristics of the electrodynamic speaker can be obtained.

  Further, in the case of the present embodiment, a diaphragm complete product in which the speaker diaphragm, the edge, and the reinforcing body are integrally formed can be obtained in one process, and the material cost and molding related to the edge and the reinforcing body are obtained. The construction cost is no longer required. In addition, the material cost and application of the adhesive for bonding the speaker diaphragm to the edge and the edge and the reinforcing paper, the construction cost for the bonding, and the material cost and the coating work of the adhesive for the medome of the bonded portion Expense is unnecessary. The number of man-hours required to produce this diaphragm finished product is 85 seconds in total including bonding when the speaker diaphragm 2 and the edge 3 are separate from each other. Since it takes only 15 seconds in total of 5 seconds, a diaphragm complete product can be obtained in about 1/6 man-hours. Compared to the electrodynamic loudspeaker of the previous embodiment, the number of components can be reduced, the overall weight can be reduced, and the cost can be reduced.

  Next, an electrodynamic speaker 1B including the speaker diaphragm 2B (not shown) and the edge 3B (not shown) of the present embodiment will be described. The speaker diaphragm 2B is the same as the speaker diaphragm 2A of Example 2 described above in that a polyurethane elastomer film is heat-sealed to the front and back surfaces of the extruded polystyrene paper, and thus the description thereof is omitted. . The size and shape of the edge 3B are the same as those in the previous embodiment. However, the material constituting the edge 3B and its arrangement are different from those of the previous embodiments.

  In the edge 3B of the present embodiment, the material constituting the free edge portion that freely supports both ends of the short-diameter direction of the speaker diaphragm 2B on the long side of the track shape extending linearly in the long-diameter direction of the speaker diaphragm 2B The first diaphragm 21B and the second diaphragm 22B are selected differently. That is, the first free edge portion 31B corresponding to the first diaphragm portion 21B to which the voice coil 4 is attached has its stiffness k1 rather than the stiffness k2 of the second free edge portion 32B corresponding to the second diaphragm portion 22B. Is a free edge formed of a soft material with a small size.

  Specifically, the first free edge portion 31B that freely supports the minor axis direction end of the first diaphragm portion 21B is a lightweight and soft edge obtained by bonding two polyurethane elastomer films with an adhesive, The second free edge portion 32B that freely supports the short-diameter end of the second diaphragm portion 22B is an edge formed by sandwiching an urethane foam edge having a thickness of about 0.3 mm between the two polyurethane elastomer films. It is heavier and harder than the first free edge portion 31B. For example, in this embodiment, the stiffness k1 of the first free edge portion 31B is about 250 N / m, whereas the stiffness k2 of the second free edge portion 32B is a large value of about 400 N / m.

  FIG. 7 is a graph illustrating the reproduction sound pressure frequency characteristics of the electrodynamic speaker 1B including the elongated speaker diaphragm 2B and the edge 3B according to the present embodiment. Similar to the previous embodiment, the average thickness t1 of the first diaphragm 21B of the speaker diaphragm 2B is formed to be thinner than the thickness t2 of the diaphragm of the second diaphragm 22B. Playback efficiency is improved, and an electrodynamic speaker with a wide playback band is realized. In the electrodynamic speaker 1B of the present embodiment, the first free edge portion 31B that freely supports both ends in the minor axis direction of the first diaphragm portion 21B has a soft and light edge. The regeneration efficiency can be further improved.

  In addition, when the material which comprises the 1st free edge part 31B and the material which comprises the 2nd free edge part 32B differ, when the material is the same, the thickness of the roll of an edge should be varied. Thereby, the mutual relationship of the stiffness may be adjusted. If the edge 3B of this embodiment is an edge formed by two-color molding using two different rubber materials or resin materials, the material arrangement is set according to the elastic modulus of the material, and the shape of the edge is optimized. By doing so, the stiffness of the first free edge portion 31B and the second free edge portion 32B can be adjusted.

FIG. 8 is a diagram illustrating a speaker diaphragm 2C and an edge 3C according to another embodiment. FIG. 8A is a perspective view of the speaker diaphragm 2C and the edge 3C as viewed obliquely from the front side, and FIG. 8B is a cross-sectional view of the speaker diaphragm 2C and the edge 3 taken along the line AA ′. It is the figure which expanded the part. As will be described later, a part of the structure of the speaker diaphragm 2C and the edge 3C, a cross-sectional structure, and the like are omitted. Further, the direction in which the straight line connecting the points AA ′ extends is the major axis direction, and the point BB ′.
The direction in which the straight line connecting the two extends is the minor axis direction.

  The speaker diaphragm 2C of the present example is formed by molding a polypropylene (PP) sheet that is extruded and has a substantially uniform thickness so as to have reinforcing ribs by using a vacuum forming method in combination with plug assist molding. Yes. Specifically, the speaker diaphragm 2C is made of a 10-fold expanded extruded foamed polypropylene sheet (thickness: about 1.1 mm) blended with 10% acrylic as a raw material, and the diaphragm is formed by the above-described vacuum forming method combined with plug assist molding. Is formed. As for the outline outline dimensions of the track-shaped speaker diaphragm 2C, the major axis direction length L1 is about 262.0 mm and the minor axis direction length L2 is about 25.5 mm. The first diaphragm portion 21C and the second diaphragm portion 22C of the speaker diaphragm 2C are defined in the same manner as in the previous embodiment.

  In other words, the first diaphragm portion 21C has two long sides of the elongated speaker diaphragm 2 and two virtual lines X that cross between the long sides in the minor axis direction at the center of the speaker diaphragm 2C. And X ′, a substantially rectangular region. In the case of the present embodiment, the distance between the imaginary lines X and X ′ is about 34.0 mm, which is larger than the diameter of the voice coil bobbin 4 and within about ½ of the length L1 in the major axis direction of the speaker diaphragm 2C. Can be set. As shown in the enlarged cross-sectional view of FIG. 8B, the first diaphragm portion 21C that contributes to the reproduction of the middle sound range and the high sound range is one end of a voice coil bobbin 4 (not shown) having a substantially cylindrical shape at the center on the back side. Is attached, and the inner side of the circular flat portion 23C is dome-shaped. Further, the outer side of the circular flat portion 23C has a substantially cone shape having a rising edge, and has a shape connected to a second diaphragm portion 22C described later.

  Further, the second diaphragm portion 22C has two long sides of the elongated speaker diaphragm 2C, the short side of the elongated speaker diaphragm 2C, and the above-described ends on both ends of the elongated speaker diaphragm 2C. This is an area defined by the virtual line X (or X ′). The short side portion of the track-shaped speaker diaphragm 2C of the present embodiment includes a semicircular portion that defines the track shape. In the case of the present embodiment, the average thickness of the second diaphragm portion 22C is about 1.1 mm, which is the same as that of the first diaphragm portion 21C, and is formed to have a substantially uniform thickness.

  In the speaker diaphragm 2C of the present embodiment, since the entire shape thereof is formed to have a substantially uniform thickness, the rigidity required in the major axis direction can be ensured by devising the arrangement and shape of the reinforcing ribs. . Specifically, the speaker diaphragm 2C has reinforcing ribs extending in the major axis direction and the minor axis direction, respectively, and the minor axis direction cross-sectional shape is substantially W-shaped. In the case of the present embodiment, among the reinforcing ribs, the long-diameter central rib 24 has two separated long-diameter central first ribs 241 and a long-diameter central first rib 241 arranged across the joint portion with the voice coil bobbin 4 (not shown). A projecting dome part that protrudes is formed at the center of the circular flat part 23 </ b> C that is composed of two ribs 242 and constitutes the joint part. Then, two long-diameter end ribs 25C formed at both ends in the minor axis direction of the speaker diaphragm 2C are formed continuously over the first diaphragm portion 21C and the respective second diaphragm portions 22C. The

  As shown in FIG. 8, the long-diameter central first rib 241 and the long-diameter central second rib 242 arranged symmetrically with respect to the center point O include the first diaphragm portion 21 </ b> C and the respective second diaphragm portions 22 </ b> C. It is formed continuously over. Further, the long-diameter central first rib 241 and the long-diameter central second rib 242 each have the long-diameter central rib height YL that defines the rib height, which is the highest in the first diaphragm 21 and in the second diaphragm 22. It becomes low as it goes to one end part in the major axis direction. Furthermore, the long diameter central first rib 241 and the long diameter central second rib 242 have the widest width defined when the speaker diaphragm 2C is viewed from the front, and are the widest in the first diaphragm 21 and in the second diaphragm 22. The width becomes narrower toward one end in the major axis direction. In the first diaphragm portion 21C, two long-diameter end ribs 25C are formed at both ends in the minor axis direction outside the circular flat portion 23C, and a convex dome portion is formed inside the circular flat portion 23C. Therefore, even if the long-diameter central first rib 241 and the long-diameter central second rib 242 are separated, the rigidity in the long-diameter direction of the speaker diaphragm 2 is improved and, as will be described later, a relatively flat reproduced sound pressure frequency. Characteristics can be realized.

  On the other hand, the edge 3C is an edge having a different shape of the reinforcing body 34C at the outer peripheral end, and an edge having substantially the same configuration as that described in the first embodiment, and has a cut inner diameter of about 259.5 mm × about 22.0 mm. A track-shaped edge having a semicircular arc radius of about 11.0 mm. Specifically, the edge 3C is a free edge portion (first free edge portion 31C) that freely supports both ends of the speaker diaphragm 2C in the short diameter direction on the long side of the track shape extending linearly in the long diameter direction of the speaker diaphragm 2C. And a second free edge portion 32C.) And a fixed edge portion 33C that fixes and supports the speaker diaphragm 2C on the short side of the track shape that is arcuate, and has a flexible foam rubber. Is injected into a mold and heated and foamed. After applying a heat-fusible adhesive to the outer periphery of the speaker diaphragm 2C and drying it, the speaker diaphragm 2C and the edge 3C are attached by hot pressing with an attaching mold, and the reinforcing body 34C is also used. An integrally formed diaphragm can be obtained.

  Therefore, the electrodynamic speaker 1C (not shown) including the elongated speaker diaphragm 2C and the edge 3C of the present embodiment is flexibly supported by the compliance of the free edge portion of the edge 3C in the minor axis direction, In the major axis direction, bending vibration is caused by the flexibility of the thermoplastic resin foam sheet forming the speaker diaphragm C2. As a result, as will be described later, the symmetry of the longitudinal amplitude of the speaker diaphragm 2C can be improved by the rigidity of the long-diameter central first rib 241 and the long-diameter central second rib 242, so that the reproduced sound quality with less distortion is excellent. An electrodynamic speaker is realized.

  FIG. 9 is a graph for explaining the reproduction sound pressure frequency characteristics of the electrodynamic speaker 1C including the elongated speaker diaphragm 2C and the edge 3C of the present embodiment. FIG. 10 is a graph showing the amount of displacement of the front-rear amplitude when a driving force is applied to the voice coil 4 having the speaker diaphragm 2C in the electrodynamic speaker 1C of the present embodiment. The characteristic curve of the graph is folded by taking the absolute value of, and when the front-rear symmetry is good, the forward displacement curve and the backward displacement curve are displayed so as to overlap.

  As shown in FIG. 9, the electrodynamic speaker 1C according to the present embodiment is improved in the asymmetry of the front-rear amplitude seen in the case of the comparative example in the previous embodiment, and the even-order distortion caused by the front-rear asymmetry. In addition, it is possible to reduce the occurrence of malfunction such as the generation of flapping noise. Further, the electrodynamic speaker 1C including the elongated speaker diaphragm 2C and the edge 3C according to the present embodiment realizes a relatively flat frequency characteristic as in the other embodiments, as shown in FIG. And the longitudinal symmetry of the displacement is improved, and as a result, good audio reproduction is possible.

  These speaker diaphragms of the present embodiment may be other narrow shapes or speaker diaphragms having different dimensions corresponding to the voice coil diameter. In addition, the electrodynamic speaker using this is not limited to a track-type speaker diaphragm, but an elongated electrodynamic speaker having a large ratio between the major axis dimension and the minor axis dimension such as an ellipse, an ellipse, a rectangle, and a rectangle. If it is.

  The speaker magnetic circuit of the present embodiment may be a magnetic circuit having different dimensions corresponding to other voice coil diameters. Regardless of whether the magnetic circuit is an internal magnetic type, an external magnetic type, or a repulsive type, the horizontal width of the magnetic circuit is smaller than the horizontal width of the elongated frame, and a substantially cylindrical voice coil is located at the center of the back of the speaker diaphragm. An electrodynamic speaker using another magnetic circuit may be used as long as it can be attached to the speaker.

  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 a figure explaining the electrodynamic speaker 1 by preferable embodiment of this invention. Example 1 It is a figure explaining the speaker diaphragm 2 and the edge 3 by preferable embodiment of this invention. Example 1 It is a figure explaining the speaker diaphragm 2 and the edge 3 by preferable embodiment of this invention. Example 1 It is a graph explaining operation | movement of the electrodynamic type speaker 1 by preferable embodiment of this invention. Example 1 5 is a graph showing the amount of displacement of the front-rear amplitude when a driving force is applied in the electrodynamic speaker 1 according to a preferred embodiment of the present invention. Example 1 It is a graph explaining the reproduction | regeneration sound pressure frequency characteristic of the electrodynamic speaker 1B by other preferable embodiment of this invention. (Example 3) It is a figure explaining the speaker diaphragm 2C and edge 3C by preferable embodiment of this invention. (Example 4) 5 is a graph showing the amount of displacement of the longitudinal amplitude when a driving force is applied in the electrodynamic speaker 1C according to a preferred embodiment of the present invention. (Example 4) It is a graph explaining the reproduction | regeneration sound pressure frequency characteristic of the electrodynamic type speaker 1C by other preferable embodiment of this invention. (Example 4)

Explanation of symbols

1, 1C Electrodynamic type speaker 2, 2A, 2B, 2C Speaker diaphragm 21, 21C First diaphragm part 22, 22C Second diaphragm part 23, 23C Circular flat part 24, 241, 242 Long diameter central rib 25, 25C Long-diameter end ribs 26, 26C Short-diameter end ribs 3 Edge 31 First free edge portion 32 Second free edge portion 33 Fixed edge portion 34 Reinforcement body 4 Voice coil 5 Damper 6 Frame 7 Terminal 8 Kinshi wire 10 Magnetic circuit 11 Top plate 12 Center pole 13 Magnetic gap 14 Under plate 15a, 15b Main magnet

Claims (8)

A speaker diaphragm comprising: an elongated diaphragm body having a major axis direction and a minor axis direction; and an edge supporting an outer peripheral edge of the diaphragm body,
The diaphragm main body includes a first diaphragm portion including a joint portion with a voice coil bobbin at a central portion on the back surface side, and second diaphragm portions respectively extending on both ends in the major axis direction of the first diaphragm portion. And the first diaphragm part, and a reinforcing rib formed continuously over each of the second diaphragm part,
The edge is formed to have a thickness that is thicker than the free edge portion, a free edge portion that freely supports the first diaphragm portion and the end of the minor axis direction of the second diaphragm portion, and the second vibration portion. A fixed edge portion that fixes and supports one end of the plate portion in the major axis direction,
Speaker diaphragm. The first diaphragm portion of the diaphragm main body has a surface area having an area larger than the projected cross-sectional area of the voice coil bobbin, and a first average thickness value defining an average thickness of the first diaphragm portion is The second diaphragm portion is configured to have a value smaller than a second average thickness value that defines an average thickness of the second diaphragm portion.
The speaker diaphragm according to claim 1. The reinforcing ribs have long-diameter end ribs formed at both ends in the short-diameter direction of the diaphragm main body, long-diameter central ribs formed at the central portion in the short-diameter direction of the diaphragm main body, Two short-diameter end ribs formed at one end in the major axis direction of the two diaphragms,
The short-diameter end ribs connect the long-diameter end ribs and do not connect the long-diameter central ribs,
The speaker diaphragm according to claim 1 or 2. The long-diameter central rib of the reinforcing rib is composed of two separate long-diameter central first ribs and long-diameter central second ribs that are arranged across the joint portion with the voice coil bobbin,
The long-diameter central rib heights that define the rib heights of the long-diameter central first rib and the long-diameter central second rib are the highest in the first diaphragm portion, respectively, As you head towards the end of the
The speaker diaphragm according to claim 3. The diaphragm main body includes a thermoplastic resin foam sheet that is extruded and laminated on the surface with a thermoplastic resin film, and the diaphragm main body, the free edge portion, and the fixed edge portion are integrally molded. The edge is bonded with an adhesive,
The speaker diaphragm according to any one of claims 1 to 4. The diaphragm main body includes a thermoplastic foam sheet that is extruded and laminated with a thermoplastic resin film on a front surface and a back surface, and the edges extend from the front surface and the back surface of the diaphragm body. A reinforcing body that includes a thermoplastic resin film, the diaphragm main body and the edge, and a thermoplastic resin foam sheet in which a front surface and a back surface are laminated with the thermoplastic resin film and supports an outer peripheral edge of the edge; , One-piece,
The speaker diaphragm according to any one of claims 1 to 4. The free edge portion of the edge freely supports the first free edge portion that freely supports the end portion in the minor axis direction of the first diaphragm portion and the end portion in the minor axis direction of the second diaphragm portion. A second free edge portion to support,
The stiffness k1 of the first free edge portion is configured to be smaller than the stiffness k2 of the second free edge portion.
The speaker diaphragm according to any one of claims 1 to 6. The speaker diaphragm according to any one of claims 1 to 7, a frame to which an outer peripheral end side of the edge is fixed, a magnetic circuit having a magnetic gap fixed to the frame, and wound around the voice coil bobbin A voice coil, and a damper for disposing the voice coil in the magnetic gap,
Electrodynamic type speaker.