Speaker

Abstract

To provide a speaker which is excellent in durability, in a severe temperature environment.SOLUTION: A speaker 10 includes a magnetic circuit 20, a diaphragm 30, and a resin-made frame 40 which is fixed to the magnetic circuit 20. The frame 40 has: a plurality of holding parts 48 for holding the magnetic circuit 20 provided in its circumferential direction; and a plurality of space parts 49 provided between the holding parts 48, and the space part 49 is formed of a space between an outer peripheral surface of the magnetic circuit 20 and an inner peripheral surface of the frame 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a speaker. [Background technology]

[0002] In recent years, AVAS (Automotive Vehicle Alert System) and other systems used as a safety measure for pedestrians have become more susceptible to harsh temperature environments because the speakers are installed in the engine compartment of a vehicle. As a result, the temperature testing requirements for in-vehicle speakers, which confirm whether they can perform properly, are becoming stricter than ever before, both at low and high temperatures. Speakers that are more durable in such harsh temperature environments are being demanded.

[0003] For example, Patent Documents 1 and 2 have proposed speakers that can withstand changes in temperature environment by providing slits in a resin frame that are radially arranged around a magnetic circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3959185 [Patent Document 2] Patent No. 2778129 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if radial slits are provided in the resin frame as in the prior art described in Patent Documents 1 and 2, since a large portion of the magnetic circuit is covered by the resin frame as described above, there are problems such as poor heat dissipation performance and crack resistance, and the inability to withstand more severe temperature environments.

[0006] The present invention has been proposed to solve the problems of the prior art as described above, and an object of the present invention is to provide a speaker that is highly durable in harsh temperature environments. [Means for solving the problem]

[0007] The speaker of the present invention has the following configuration. (1) A magnetic circuit, a diaphragm, and a resin frame fixed to the magnetic circuit. (2) The frame has a plurality of holding portions arranged in the circumferential direction thereof to hold the magnetic circuit, and a plurality of spaces provided between the plurality of holding portions. (3) The space is formed by the space between the outer peripheral surface of the magnetic circuit and the inner peripheral surface of the frame.

[0008] In the present invention, the following configuration can be adopted. (1) The peripheral length of the space is greater than the peripheral length of the holding portion. (2) The frame is formed by injection molding, and the magnetic circuit is held in the holding portion by insert molding. (3) The frame includes a covering portion that covers the space portion. (4) The magnetic circuit includes a plate or a yoke, the holding portion holds the plate or the yoke, and the space portion is formed by the space between the outer surface of the plate or the yoke and the inner surface of the frame. (5) A step is provided on the outer peripheral surface of the plate or the yoke, and the holding portion holds the step. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a speaker that is highly durable in harsh temperature environments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a speaker according to a first embodiment. [Figure 2] FIG. 2 is an end view showing a magnetic circuit and a frame in the first embodiment. [Figure 3] FIG. 2 is an end view showing a magnetic circuit and a holding portion in the first embodiment. [Figure 4] FIG. 3 is a horizontal cross-sectional view showing a plurality of holding portions and a plurality of spaces in the first embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a speaker according to a second embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing a magnetic circuit and a holding portion in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [1. First embodiment] [1-1.Configuration] (1) Overall structure The speaker 10 of this embodiment will be described below with reference to Figures 1 to 4. The speaker 10 of this embodiment is intended to be mounted in a vehicle or the like in various directions for use, and therefore its vertical positional relationship may vary. However, for the sake of convenience, the following description will be given with the magnetic circuit 20 side as the bottom and the diaphragm 30 side as the top. The speaker 10 of this embodiment is substantially symmetrical about the central axis A of the voice coil 50 shown in Figure 1.

[0012] 1, speaker 10 includes magnetic circuit 20, diaphragm 30, and resin frame 40. Speaker 10 uses external magnetic type magnetic circuit 20 in which ring-shaped magnet 22 is arranged to surround voice coil 50, but as will be described later, internal magnetic type magnetic circuit 620 in which voice coil 50 surrounds cylindrical magnet 622 may also be used.

[0013] (2) Magnetic circuit As shown in FIG. 1, magnetic circuit 20 includes yoke 21, magnet 22, and plate 23. Yoke 21 is rotationally symmetric about central axis A of speaker 10. As shown in FIG. 1, yoke 21 includes base portion 211, pole portion 212, and flange portion 213. Base portion 211 forms the lower end side of yoke 21 and has a recess 214 in its central portion. Pole portion 212 is configured in a bottomed cylindrical shape that protrudes upward from the center of base portion 211 on the inner diameter side of voice coil 50. Flange portion 213 is located on the outer periphery of base portion 211 and is fixed to the lower end of magnet 22.

[0014] The magnet 22 is a hard magnetic material (permanent magnet) and is formed in an annular shape around the central axis A so as to surround the voice coil 50. The magnet 22 is disposed on the outer periphery of the voice coil 50 and is fixed between the flange portion 213 of the yoke 21 and the plate 23.

[0015] The plate 23 is also called a pole piece. As shown in FIG. 1, the plate 23 is formed in an annular shape around the central axis A and is disposed on the outer periphery of the voice coil 50. As shown in FIG. 4, the lower surface of the plate 23 is fixed to the upper surface of the magnet 22. A step 231 is provided on the outer periphery of the plate 23. The step 231 is a recess extending from the outer periphery of the plate 23 toward the inner periphery. The step 231 is held by a holding portion 48 of the frame 40 (described later), thereby fixing the magnetic circuit 20 and the frame 40. As shown in FIG. 1, the voice coil 50 is disposed in the magnetic gap 24 formed between the pole portion 212 of the yoke 21 and the magnet 22 and plate 23. The plate 23 of this embodiment is formed of SPCC-equivalent (steel), which has a linear expansion coefficient (10-6 / K) of 11.7.

[0016] (3) Vibration plate The diaphragm 30 is formed in an annular shape around the central axis A, and has a cone shape with the central axis A side recessed downward relative to the outer periphery. The diaphragm 30 is formed, for example, from cone paper (a cone made of a material containing pulp fibers, etc.). A center cap 31 is fixed to the upper center of the diaphragm 30. The center cap 31 is formed in a dome shape, with its central portion bulging upward. An edge 32 made of an elastic material such as rubber is fixed around the outer periphery of the diaphragm 30, all around the periphery. The edge 32 is formed in an annular shape around the central axis A, and is fixed to the frame 40 all around the periphery.

[0017] (4) Frame The frame 40 is made of resin, such as ABS resin made of acrylonitrile, butadiene, and styrene copolymer synthetic resin, polyolefin resin such as polyethylene (PE) and polypropylene (PP), polyester resin such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyimide (PI), polyether ketone (PEK), polyphenylene sulfide (PPS), or polyetherimide (PEI). The frame 40 of this embodiment is made of polypropylene (PP) resin, which has a linear expansion coefficient (10-6 / K) of 100.

[0018] Frame 40 is a resin product molded by injection molding. During injection molding, plate 23 of magnetic circuit 20 is fixed to the inside of frame 40 by insert molding, in which resin is injected and solidified while plate 23 is placed in a mold. The upper part of frame 40 expands into a cone shape to accommodate diaphragm 30. The lower part of frame 40 forms a cylindrical space to accommodate magnetic circuit 20. As shown in FIG. 1 , a mounting portion 41 is provided in the approximate center of frame 40. The mounting portion 41 protrudes from the inner circumferential surface of frame 40 toward the inside of frame 40 to separate a housing portion MS for magnetic circuit 20 from a housing portion DS for diaphragm 30. An opening 41a is provided in the center of mounting portion 41, through which the lower part of voice coil 50 is disposed.

[0019] In the housing portion DS of the diaphragm 30, the frame 40 includes, from above, an upper edge portion 42 that surrounds the outer periphery of the upper end of the diaphragm 30, an upper step portion 43 that secures the upper end of the diaphragm 30, a tapered portion 44 that is disposed along the cone-shaped portion of the diaphragm 30, and a lower step portion 45 that supports the outer periphery of the damper 60 (described later). The housing portion MS of the frame 40 is formed by a cylindrical portion 46 having an internal space, and surrounds the magnetic circuit 20, which is a roughly cylindrical block, from the outer periphery. As shown in FIGS. 1 and 2, the cross-sectional shape of the cylindrical portion 46 becomes thinner as it goes toward the lower end 461, and the lower end 461 protrudes downward further than the flange portion 213 of the yoke 21.

[0020] As shown in the horizontal cross-sectional view of the cylindrical portion 46 in FIG. 4 , the frame 40 has a plurality of (four in FIG. 4 ) holding portions 48 provided at predetermined intervals in the circumferential direction thereof, and the magnetic circuit 20 is held to the frame 40 by these holding portions 48. In this embodiment, the holding portions 48 secure the plate 23 fixed to the upper part of the magnetic circuit 20 to the cylindrical portion 46 of the frame 40, and a plurality of (four in FIG. 4 ) arc-shaped spaces 49 are provided between each holding portion 48. As shown in FIG. 3 , the holding portions 48 are formed integrally with the cylindrical portion 46 and have a claw-like shape that protrudes inward from the inner circumferential surface of the cylindrical portion 46. The holding portions 48 are held by step portions 231 provided on the outer periphery of the plate 23, thereby fixing the cylindrical portion 46 and the plate 23 together. For example, when the frame 40 is molded and fixed to the outer periphery of the plate 23 by insert molding, a portion of the resin that makes up the frame 40 flows into the step portion 231 of the plate 23 and solidifies, thereby fixing the step portion 231 and the retaining portion 48 together.

[0021] The space 49 is formed by the space between the outer peripheral surface of the magnetic circuit 20 and the inner peripheral surface of the frame 40. In this embodiment, as shown in Fig. 2, a space is formed between the outer peripheral surface of the plate 23 fixed to the top of the magnet 22 and the inner peripheral surface of the cylindrical portion 46 of the frame 40, constituting the space 49. The arc-shaped space 49 provided between the multiple holding portions 48 is shown as the space between the outer peripheral surface of the plate 23 and the inner peripheral surface of the cylindrical portion 46 in the horizontal cross-sectional view of Fig. 4.

[0022] There may be a plurality of holding portions 48 and space portions 49, but from the viewpoint of ensuring the heat dissipation performance of magnetic circuit 20 and preventing cracks from occurring in frame 40, it is preferable that there are three to six of them. In addition, frame 40 is formed so that the circumferential length of space portions 49 is greater than the circumferential length of holding portions 48.

[0023] The frame 40 includes a covering portion 47 that covers the space 49. That is, a portion of the mounting portion 41 close to the inner circumferential surface of the cylindrical portion 46 forms the covering portion 47 that covers and closes the space 49 from above.

[0024] (5) Voice coil The voice coil 50 has a cylindrical bobbin 51 and a substantially cylindrical coil 52 wound around the outer circumferential surface of the bobbin 51. The voice coil 50 is capable of linearly reciprocating motion along a central axis A. The coil 52 is connected to a connection terminal. The inner circumferential portion of a damper 60 is connected to the bobbin 51. Furthermore, the inner circumferential portion of the diaphragm 30 is connected to the top of the bobbin 51, and the outer circumferential edge of the diaphragm 30 is fixed to the upper step portion 43 of the frame 40 via an edge 32.

[0025] (6) Damper The voice coil 50 is held to the frame 40 by a damper 60. The damper 60 is formed in an annular shape around the central axis A, and its outer periphery is fixed to the frame 40, while its inner periphery is fixed to the outer periphery of the bobbin 51.

[0026] [1-2. Assembly procedure of the embodiment] The assembly procedure for the speaker 10 of this embodiment will be described. First, the plate 23 and the frame 40 are fixed together by insert molding. Specifically, the mold used to injection-molde the frame 40 is provided with a recess for placing the plate 23 and a hollow portion into which the frame 40 is injected by injection molding. In this case, recesses are formed in the mold portion facing the step portions 231 of the plate 23 at the four holding portions 48 that hold the plate 23, since resin is injected into the holding portions 48. Meanwhile, protrusions of the mold are inserted between the outer peripheral surface of the plate 23 and the surface of the step portions 231 to prevent the resin from being injected into the four spaces 49 formed between the holding portions 48. With the plate 23 fitted into the recesses of the injection mold, resin such as PP resin is injected. After the resin hardens, the integrated plate 23 and frame 40 are removed from the mold. In this way, spaces 49 are formed between the outer peripheral surface of the plate 23 and the inner peripheral surface of the frame 40.

[0027] Next, the magnet 22 and the yoke 21 are fixed to the plate 23 to form the magnetic circuit 20 .

[0028] The voice coil 50, which is formed by winding a coil 52 around a bobbin 51, the center cap 31, and the edge 32 are fixed to the diaphragm 30 with an adhesive or the like. The diaphragm 30 in this fixed state is then fixed to the upper step portion 43 of the frame 40 with an adhesive or the like. In this fixing, the voice coil 50 fixed to the diaphragm 30 is inserted into the magnetic gap 24 between the inner diameter of the plate 23 and the cylindrical outer diameter of the pole portion 212.

[0029] [1-3. Operation of the embodiment] When a current flows through the voice coil 50 disposed in the magnetic gap 24, a force is generated, causing the voice coil 50 to reciprocate along the central axis A. This causes the diaphragm 30 to vibrate vertically, thereby generating sound from the speaker 10. In this embodiment, the frame 40 has multiple holding portions 48 arranged circumferentially to hold the magnetic circuit 20, and multiple spaces 49 provided between each holding portion 48. Therefore, even if the resin frame 40 shrinks significantly at low temperatures, the spaces 49 absorb the shrinkage, thereby preventing cracks from occurring in the resin frame. Furthermore, even if the resin frame 40 expands more than the metal magnetic circuit 20 (plate 23) at high temperatures, the spaces 49 can absorb the expansion.

[0030] [1-4. Effects of the embodiment] (1) In this embodiment, the frame 40 has a plurality of holding portions 48 arranged in the circumferential direction thereof to hold the magnetic circuit 20, and a plurality of spaces 49 provided between the holding portions 48. Therefore, compared to the prior art configuration in which the magnetic circuit 20 and the frame 40 are fixed together without providing spaces 49 between them, it is possible to provide a speaker 10 that is highly durable in harsh temperature environments.

[0031] That is, because speaker 10 is generally constructed by combining multiple parts with different linear expansion coefficients, such as resin and metal, significant temperature changes can cause stress between the parts, potentially causing damage such as cracks in the resin parts, which have relatively low strength. In particular, speaker 10 includes metal magnetic circuit 20, such as yoke 21 and plate 23, and diaphragm 30 fixed thereto, as well as resin frame 40 fixed to magnetic circuit 20 by insert molding or other methods.

[0032] In the prior art, there is a problem that cracks occur in the frame 40 in a severe temperature environment due to the difference in thermal expansion between the metal magnetic circuit 20 and the resin frame 40. In this embodiment, the problem of the prior art can be solved by providing holding portions 48 in only a few places and not surrounding the outer periphery in other places.

[0033] Furthermore, in this embodiment, compared to the prior art in Patent Documents 1 and 2 in which radial slits are formed, it is possible to provide a space between the magnetic circuit 20 and the frame 40 that can be freely designed, and the multiple holding portions 48 can reliably fix both of them while reliably absorbing differences in thermal expansion, so there is no risk of damaging the speaker even under harsh environmental conditions.

[0034] (2) The frame 40 is formed so that the perimeter of the space 49 is greater than the perimeter of the holding portion 48. Therefore, even if the resin frame 40 shrinks significantly at low temperatures, the space 49 absorbs the shrinkage, thereby preventing cracks from occurring in the resin frame 40. Furthermore, even if the resin frame 40 expands more than the metal magnetic circuit 20 (plate 23) at high temperatures, the space 49 can absorb the expansion. Furthermore, because only a small portion of the metal magnetic circuit 20 is covered by the frame 40, the speaker 10 can be provided with a high degree of design freedom while ensuring the heat dissipation performance of the magnetic circuit 20.

[0035] (3) The frame 40 is formed by injection molding, and the magnetic circuit 20 is fixed to the holding portion 48 by insert molding. This reduces the number of assembly steps. Furthermore, reliability is improved when the magnetic circuit 20 and the frame 40 are fixed, improving product durability.

[0036] (4) The frame 40 of this embodiment has a covering portion 47 that covers the space portion 49, thereby preventing foreign matter from outside the diaphragm 30 from entering the magnetic circuit 20 side inside the speaker 10, thereby providing a speaker 10 with excellent durability.

[0037] (5) The magnetic circuit 20 includes a plate 23, the holding portion 48 is fixed to the plate 23, and the space 49 is formed by the space between the outer peripheral surface of the plate 23 and the inner peripheral surface of the frame 40. This ensures the performance of the magnetic circuit, prevents cracks from occurring due to differences in the linear expansion coefficients of metal and resin, and provides a speaker with excellent durability.

[0038] (6) A step 231 is provided on the outer peripheral surface of the plate 23, and the retaining portion 48 retains the step 231. It is possible to retain the plate 23 without providing the step 231 by increasing the outer diameter of the plate 23, but increasing the outer diameter of the plate 23 increases the leakage magnetic flux of the magnetic circuit 20. Providing the step 231 prevents the diameter of the plate 23 from being increased, reduces the leakage magnetic flux, and also reduces costs by reducing the amount of material used.

[0039] [2. Second Embodiment] In the second embodiment, the present invention is applied to a speaker 600 having an internal magnet type magnetic circuit 620 instead of the external magnet type magnetic circuit 20 of the first embodiment. As shown in FIG. 5 , the second embodiment includes a cylindrical magnet 622 and a cylindrical plate 623 housed inside a cylindrical voice coil 50, and a cup-shaped yoke 621 surrounding the magnet 622, plate 623, and voice coil 50. The yoke 621 includes a base portion 6211 provided at the bottom of the cup, a side wall portion 6215 extending from the base portion 6211 to the outer periphery of the magnet, and a flange portion 6213 provided at the upper end of the side wall portion 6215. The base portion 2111 forms the lower end side of the yoke 621 and has a recess 6214 in its central portion. The magnet 622 and the inner voice coil 50 are fixed to the base portion 6211 of the yoke 621.

[0040] In such an internal magnet type speaker 600, with the underside of flange portion 6213 of yoke 621 overlapped with mounting portion 641 provided on frame 640, holding portion 648 provided on mounting portion 641 holds flange portion 6213, thereby fixing magnetic circuit 620 and diaphragm 30 to frame 640. That is, holding portion 648 of frame 640 is fixed to the outer periphery of flange portion 6213 by insert molding, as in the first embodiment. Note that in this embodiment, no step is provided at the end of flange 6213, and the end of flange portion 6213, which is formed perpendicularly, is embraced by holding portion 648, but a step may also be provided on flange portion 6213, as in the outer periphery of plate 23 in the first embodiment.

[0041] In the second embodiment, a space 649 formed between the frame 640 and the magnetic circuit 620 is formed by the space between the outermost peripheral surface of the flange 6213 and the inner peripheral surface of the frame 640. This space is covered by a covering portion 647 provided on a part of the mounting portion 41.

[0042] Other configurations, such as the positions, number, and shapes of the holding portions 648 and the spaces 649, can be the same as those in the first embodiment.

[0043] In the second embodiment having such a configuration, similar to the first embodiment, even in speaker 600 having internal magnet type magnetic circuit 620, the stress between magnetic circuit 620 and frame 640 generated by the difference in thermal expansion can be absorbed by multiple spaces 649, and the occurrence of cracks in frame 640 can be prevented even in severe temperature environments. Moreover, internal magnet type magnetic circuit 620 using a neodymium magnet or the like can place magnet 622 inside voice coil 50, which enables the outer diameter of speaker 600 to be reduced, thereby realizing miniaturization of speaker 600. Another advantage of such internal magnet type magnetic circuit 620 is that leakage magnetic flux to the outside is small.

[0044] In the second embodiment, if a step is provided on the outer peripheral surface of flange portion 6213 of yoke 621 and holding portion 648 is configured to hold the step, the thickness of the integrated portion of yoke 621 and frame 640 can be reduced, making it possible to reduce the size of speaker 600.

[0045] 3. Other Embodiments Although several embodiments of the present invention have been described above, they are not intended to limit the scope of the invention. As listed below, the invention can be embodied in various other forms without departing from the spirit of the invention, and various omissions, substitutions, and modifications can be made. These embodiments, combinations thereof, and further modifications thereof are included within the scope and spirit of the invention, as well as within the scope of the inventions described in the claims and their equivalents. The following are examples of embodiments encompassed by the present invention.

[0046] (1) The space between the outer peripheral surface of the magnetic circuit 20,620 and the inner peripheral surface of the frame 40,640 that constitutes the space portion 49,649 is preferably 5 mm to 10 mm from the standpoint of miniaturizing the speaker 10,600 and preventing cracks from occurring in the frame 40,640, but is not necessarily limited to this.

[0047] (2) In this embodiment, the plate 23 is provided with the step portion 231, but the step portion 231 does not have to be provided. (3) As in speaker 700 having an external magnetic circuit 720 (magnet 722, plate 723) shown in Fig. 6, yoke 721 can be held by holding portion 748 (broken line in Fig. 6) of frame 740, and space 749 can be formed between the outer circumferential surface of yoke 721 and frame 740. In this case, frame 740 should be provided with a cover portion 747 that covers space 749 to prevent foreign matter from entering the interior of speaker 700.

[0048] (4) In each of the illustrated embodiments, the shape of the yoke 21 is not limited to the cylindrical shape with a bottom as shown in FIG. [Explanation of symbols]

[0049] 10,600,700...Speaker 20,620,720...Magnetic circuit 21,621,721…York 214,6214,7214...recesses 6215...Side wall 22,622,722…magnets 23,623,723…plates 231...Double part 24...Magnetic gap 30…Diaphragm 31...Center cap 32...Edge 40...frame MS: Magnetic circuit housing DS: Diaphragm housing 47...Covering part 48,648,748…Holding part 49,649,749…Space part 50...Voice coil 51...Bobbin 52...Coil 60...Damper

Claims

1. a magnetic circuit, a diaphragm, and a resin frame fixed to the magnetic circuit; the frame has a plurality of holding portions provided in a circumferential direction thereof to hold the magnetic circuit, and a plurality of spaces provided between the plurality of holding portions, The space is formed by the space between the outer peripheral surface of the magnetic circuit and the inner peripheral surface of the frame.

2. 2. The speaker according to claim 1, wherein the peripheral length of the space is greater than the peripheral length of the holding portion.

3. the frame is formed by injection molding; 3. The speaker according to claim 1, wherein the magnetic circuit is held in the holding portion by insert molding.

4. The frame includes a covering portion that covers the space portion.

3. The speaker according to claim 1 or 2.

5. the magnetic circuit comprises a plate or a yoke; the holding portion holds the plate or the yoke, 3. The speaker according to claim 1, wherein the space is formed by the space between an outer peripheral surface of the plate or the yoke and an inner peripheral surface of the frame.

6. a step is provided on an outer peripheral surface of the plate or the yoke, The speaker according to claim 5 , wherein the holding portion holds the step portion.

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