Speaker

Abstract

Provided is a speaker capable of increasing a centering effect as compared with conventional speakers. This speaker comprises: a magnet body extending in a predetermined direction; a plate-like top plate disposed on one end surface of the magnet body; a yoke having a body part disposed on the other end surface of the magnet body and a facing part extending from the body part to a position facing a side surface of the top plate; a voice coil disposed in a magnetic gap between a side surface region of the top plate and a facing region of the facing part facing the side surface region; a magnetic fluid interposed between the side surface region and the voice coil or between the facing region and the voice coil; and a protruding part protruding from one among the side surface region and the facing region toward the other. The protruding part is shorter than the side surface region of the top plate in the direction in which the magnet body extends, and is provided over the entire circumference of the facing region.

Description

Speaker Cross - reference to related applications 【0001】 This international application claims priority based on Japanese Patent Application No. 2024 - 213939 filed with the Japan Patent Office on December 6, 2024, and incorporates the entire contents of Japanese Patent Application No. 2024 - 213939 by reference into this international application. 【0002】 This disclosure relates to a speaker. 【0003】 Conventionally, a speaker is known in which a voice coil is disposed via a magnetic fluid within a magnetic gap between a yoke and a side surface of a top plate, and the voice coil is magnetically positioned within this magnetic gap (see Patent Document 1). 【0004】 In such a speaker, a centering effect can be imparted to the voice coil so that it does not shift significantly inward or outward within the magnetic gap even during operation as a speaker or when subjected to an external force. 【0005】 Japanese Patent No. 5194970 Gazette 【0006】 However, in recent years, with the expansion of applications, miniaturization of speakers has also advanced, and there are restrictions on the shape, size, and available magnets, so there is a problem that it is difficult to sufficiently enhance the centering effect. 【0007】 This disclosure has been made to solve such problems, and its object is to provide a speaker capable of enhancing the centering effect more than conventionally. 【0008】To solve the above problems, the first aspect of this disclosure is a speaker comprising: a magnet body extending in a predetermined direction and magnetized along this direction; a plate-shaped top plate disposed on one end face of the magnet body and extending along an intersecting surface that intersects the direction in which the magnet body extends; a yoke having a main body disposed on the other end face of the magnet body and extending along the intersecting surface, and a facing portion extending from the main body to a position facing the side surface of the top plate; a voice coil disposed in the magnetic gap between the side region of the top plate and the facing region of the facing portion facing this side region; a magnetic fluid interposed between the side region and the voice coil, or between the facing region and the voice coil; and a projection protruding from either the side region or the facing region toward the other, wherein the projection is shorter in the direction in which the magnet body extends than the side region of the top plate and is provided around the entire circumference of the facing region. 【0009】 In this type of speaker, a projection extends from either the side region of the top plate or the opposing region of the yoke toward the other. This increases the density of magnetic field lines extending from one of these regions toward the other, thereby increasing the local magnetic gradient in that area. As a result, the centering effect on the voice coil can be enhanced in this type of speaker. 【0010】 Furthermore, the above-mentioned phase may be as shown in the second phase below. In the second phase, the protrusion is a flange-like, single projection provided around the entire circumference of the opposing region. 【0011】 This curved speaker, with its flange-like and single projection, can increase the density of magnetic field lines from either the side region of the top plate or the opposing region of the yoke to the other. 【0012】 Furthermore, the first phase described above may be as shown in the third phase below. In the third phase, the protrusions are a plurality of projections arranged at predetermined intervals along the intersecting surface over the entire circumference of the opposing region. 【0013】This curved speaker, with its multiple protrusions arranged at predetermined intervals, can increase the density of magnetic field lines from either the side region of the top plate or the opposing region of the yoke to the other. 【0014】 Furthermore, each of the above-mentioned phases may be as shown in the fourth phase below. In the fourth phase, the top plate extends over a wider area than the magnet body in a plan view intersecting the direction in which the magnet body extends, the protruding portion protrudes from the side region, and the opposing portion is formed as a projection that extends to the side region over a wider area than the protruding portion in the direction in which the magnet body extends, and the distance L1 from the surface of the top plate along the side region to one end face of the protruding portion, the distance L2 from the back surface of the top plate along the side region to the other end face of the protruding portion, the distance L3 from the other end of the side region along the back surface of the top plate to the magnet body, the distance L4 from the end of the protruding portion on one end face to the end of the opposing region on one end face, the distance L5 from the end of the protruding portion on the other end face to the end of the opposing region on the other end face, and the protruding distance L6 from the side region of the protruding portion are each configured to have the relationship shown in the following formula. 【0015】 L1, L2 < L3 (Equation 1) L1, L2 < L6 (Equation 2) L4, L5 < L6 (Equation 3) In this type of speaker, the parameters of the top plate, protrusion, and opposing part have the relationships shown in the above equations, so that the tip of the protrusion, where magnetic field lines tend to concentrate, is closer to the opposing region than to the side region. This increases the density of magnetic field lines from either the side region of the top plate or the opposing region of the yoke to the other, and makes the local magnetic gradient in this area larger. 【0016】Front section view of a speaker according to an embodiment of this disclosure Front section view of a main part of a speaker according to an embodiment of this disclosure Perspective view (a) and front view (b) showing the top plate according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Perspective view (a) and front view (b) showing the top plate according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Front section view of a speaker according to an embodiment of this disclosure Front section view of an evaluation model according to an embodiment of this disclosure Perspective view (a) and front view (b) showing the top plate of the evaluation model according to an embodiment of this disclosure Graph showing measurement results based on the evaluation model according to an embodiment of this disclosure 【0017】 1...Speaker, 10...Magnet, 20...Top plate, 21...Side region, 23...Through hole, 30...Yoke, 31...Main body, 33...Opposite part, 35...Opposite region, 37...Through hole, 40...Voice coil, 41...Measuring piece, 50...Magnetic fluid, 60...Protrusion, 61...Projection, 70...Fluid pad, 71...Ferrite magnet, 73...Magnetic fluid, 80...Gauge, 100...Model. 【0018】 Embodiments of the present invention will be described below with reference to the drawings. (1) Overall configuration (1-1) First embodiment The speaker 1, as shown in Figures 1 and 2, comprises a magnet body 10 extending in a predetermined direction (up and down direction in the same figure), a plate-shaped top plate 20 disposed on one end face of the magnet body 10, a yoke 30 disposed on the other end face of the magnet body 10, a voice coil 40 disposed in the magnetic gap between the top plate 20 and the yoke 30, a magnetic fluid 50 interposed between the top plate 20 and the yoke 30, and a protrusion 60 protruding from either the top plate 20 or the yoke 30 toward the other. 【0019】 The magnet body 10 is magnetized along its extending direction. Furthermore, the magnet body 10 in this embodiment extends in a prism shape (specifically, a rectangular prism). 【0020】The top plate 20 is a plate-shaped member positioned on one end face of the magnet body 10 and extending along an intersecting surface that intersects the direction in which the magnet body 10 extends. In this case, it extends over a larger area than the magnet body 10 in a plan view intersecting the direction in which the magnet body 10 extends. In this embodiment, as shown in Figure 3, the top plate 20 is configured as a rectangular (specifically, quadrilateral) plate-shaped member in a plan view. 【0021】 In this embodiment, the top plate 20 is made by stacking three plate-like members, and the size of the plate-like member sandwiched in between is made larger than the others so that the outer circumference of this plate-like member becomes a protruding portion 60. 【0022】 The yoke 30 has a main body portion 31 positioned on the other end face of the magnet body 10 and extending along the intersecting surface, and a facing portion 33 extending from the main body portion 31 to a position facing the side surface of the top plate 20. In this embodiment, the main body portion 31 extends in a plate shape on the other end face side of the magnet body 10, and the facing portion 33 extends in a cylindrical shape that surrounds the sides of the magnet body 10 and the top plate 20. 【0023】 The voice coil 40 is positioned within the magnetic gap between the side region 21 of the top plate 20 and the opposing region 35 of the opposing portion 33 that faces the side region 21. In this embodiment, the voice coil 40 extends in a cylindrical shape so as to surround the side of the top plate 20 around its entire circumference. 【0024】 The magnetic fluid 50 is interposed between the side region 21 of the top plate 20 and the voice coil 40, or between the opposing region 35 and the voice coil 40. In this embodiment, the magnetic fluid 50 is interposed only between the top plate 20 and the voice coil 40. 【0025】 The protruding portion 60 projects from either the side region 21 of the top plate 20 or the opposing region 35 of the yoke 30 toward the other. In this embodiment, it protrudes from the side region 21 of the top plate 20 toward the opposing region 35 (see Figures 2 and 3). 【0026】This protrusion 60 is shorter in the direction of extension of the magnet body 10 than the side region 21 of the top plate 20, and is provided over the entire opposing region 35 of the yoke 30. More specifically, the protrusion 60 is a flange-shaped, single projection provided over the entire circumference of the opposing region 35. (1-2) Second Embodiment In this embodiment, as shown in Figure 4, the speaker 1 has an opposing portion 33, and the opposing region 35 facing the side region 21 of the top plate 20 is formed as a projection that extends toward the side region 21 over a wider area in the direction of extension of the magnet body 10 than the protrusion 60. 【0027】 Furthermore, in this embodiment, the speaker 1 is configured such that the distance L1 from the surface (upper surface) of the top plate 20 along the side region 21 to one end surface (upper surface) of the protruding portion 60, the distance L2 from the back surface (lower surface) of the top plate 20 along the side region 21 to the other end surface (lower surface) of the protruding portion 60, the distance L3 from the other end (lower end) of the side region 21 along the back surface of the top plate 20 to the magnet body 10, the distance L4 from the end (upper end) of one end surface of the protruding portion 60 to the end (upper end) of one end surface in the opposing region 35, the distance L5 from the other end (upper end) of the protruding portion 60 to the other end (upper end) of the opposing region 35, and the protruding distance L6 of the protruding portion 60 from the side region are all related by the following equation. 【0028】 L1, L2 < L3 (Equation 1) L1, L2 < L6 (Equation 2) L4, L5 < L6 (Equation 3) (2) Modifications The embodiments of the present invention have been described above, but it goes without saying that the present invention is not limited in any way to the above embodiments, and can take various forms as long as they fall within the technical scope of the present invention. 【0029】 For example, the above embodiment illustrates a speaker 1 in which each component is formed in a rectangular shape when viewed from above. However, it goes without saying that this disclosure can also be applied to speaker 1 in which each component is formed in a circular, elliptical, or track shape when viewed from above. 【0030】Furthermore, in the above embodiment, the case in which the protrusion 60 is flange-shaped and a single projection was illustrated. However, as shown in Figures 5 to 6, the protrusion 60 may be composed of a plurality of projections 61 arranged at predetermined intervals along the intersecting surface over the entire opposing region 35 of the yoke 30. In this case, each projection 61 should be arranged at an interval L7 that is wider than L6. Note that the configuration is not limited to this, but the region of the protrusion 60 that faces the rectangular corner portion of the top plate 20 should be configured to be spaced apart from the yoke 30 by an interval L7 that is wider than L6 in a plan view. 【0031】 Furthermore, the above embodiment illustrates the application of the present disclosure to an internal magnet type speaker. However, it goes without saying that the present disclosure can also be applied to an external magnet type speaker. In this case, as shown in Figure 7, each part may be configured as follows. 【0032】 First, the yoke 30 is configured such that an opposing portion 33 extends columnarly from the center of the main body portion 31. The magnet body 10 is configured to extend cylindrically so as to surround this opposing portion 33. The top plate 20 is configured to have a through hole 23 formed so as to surround the opposing portion 33. The voice coil 40 is configured to be arranged so as to surround the opposing portion 33. The magnetic fluid 50 is interposed between the side region 21 and the voice coil 40 (it may also be interposed between the opposing portion 33 and the voice coil 40). The protruding portion 60 is configured to protrude toward the opposing region 35 from the side region 21 which is the inner circumferential surface of the through hole 23 in the top plate 20, as shown in Figure 8. 【0033】Furthermore, in the above embodiment, the protruding portion 60 may be concave toward the side surface region 21, with one end surface (upper surface) and the other end surface (lower surface) of the protruding portion 60 as vertices, as shown in Figure 9. Specifically, the tip shape may be a linear concave shape (Figure (a)), or a curved concave shape (Figure (b)). (3) Operation and Effects In the speaker 1 of the above embodiment, the protruding portion 60 protrudes from either the side surface region 21 of the top plate 20 or the opposing region 35 of the yoke 30 toward the other. This increases the density of magnetic field lines toward either the side surface region 21 of the top plate 20 or the opposing region 35 of the yoke 30 toward the other, and increases the local magnetic gradient in this area. As a result, the centering effect on the voice coil 40 can be enhanced in the above curved surface. 【0034】 Figure 10 shows the results of analyzing the magnetic field generated between the side region 21 and the opposing region 35 under the same conditions for each configuration: a configuration in which the top plate 20 does not have a protrusion 60 (Figure 10(a)), a configuration in which a flange-shaped protrusion 60 consisting of a single projection is provided (Figure 10(b)), and a configuration in which a protrusion 60 consisting of multiple projections 61 is provided (Figure 10(c)). From these analysis results, it can be confirmed that in the configuration with the protrusion 60, the density of magnetic field lines extending from one side region 21 to the other of the opposing region 35 is higher than in the configuration without the protrusion 60, and the local magnetic gradient in this area is larger. 【0035】 Furthermore, the speaker 1 of the above embodiment, with its flange-like and single projection, can increase the density of magnetic field lines traveling from one of the side region 21 of the top plate 20 to the other of the opposing region 35 of the yoke 30. 【0036】 Furthermore, in the above embodiment, if the protruding portion 60 is composed of a plurality of projections 61, the density of magnetic field lines extending from one of the side region 21 of the top plate 20 and the opposing region 35 of the yoke 30 to the other can be increased by the plurality of projections 61 arranged at predetermined intervals. 【0037】Furthermore, in the speaker 1 of the second embodiment described above, the parameters of the top plate 20, the protruding portion 60, and the opposing portion 33 are in the relationship shown in the above formulas 1 to 3, so that the tip of the protruding portion 60, where magnetic field lines tend to concentrate, is closer to the opposing region 35 than to the side region 21. This increases the density of magnetic field lines from either the side region 21 of the top plate 20 or the opposing region 35 of the yoke 30 to the other, and makes the local magnetic gradient in this area larger. (4) Verification The applicant has verified the centering effect according to the shape of the top plate 20 based on the speaker model 100 shown below. 【0038】 First, the model 100 used for verification, as shown in Figure 11, comprises a magnet body 10 extending vertically, a plate-shaped top plate 20 positioned on the upper surface of the magnet body 10, a yoke 30 positioned on the lower surface of the magnet body 10, a voice coil 40 positioned in the magnetic gap between the top plate 20 and the yoke 30, magnetic fluid 50 interposed between the side region 21 of the top plate 20 and the voice coil 40, and between the voice coil 40 and the yoke 30, respectively, and a fluid pad 70 extending upward from the upper surface of the top plate 20 toward the inner circumferential surface of the voice coil 40. 【0039】 Of these, three types of top plates 20 are available: a first top plate 20 (see Figure 12) which does not have a protrusion 60 on the side region 21; a second top plate 20 (see Figure 3) which has a flange-shaped, single protrusion 60 that protrudes around the entire circumference of the side region 21; and a third top plate 20 (see Figure 6) which has a protrusion 60 consisting of multiple protrusions 61 arranged at predetermined intervals around the entire circumference of the side region 21. 【0040】 Furthermore, the yoke 30 has a through-hole 37 formed in the opposing portion 33 that surrounds the top plate 20, which penetrates the opposing portion 33 inward and outward and reaches the side surface of the voice coil 40. 【0041】Furthermore, the fluid pad 70 comprises a cylindrical ferrite magnet 71 magnetized in the axial direction and a magnetic fluid 73 positioned on its upper surface. By placing the voice coil 40 on this fluid pad 70, contact between the lower part of the voice coil 40 and the yoke 30 is prevented. 【0042】 For each model 100 employing each top plate 20, the applicant inserted a gauge 80 through a through hole 37 in the yoke 30 and pressed the voice coil 40 with a load F [g], measuring the displacement x [mm] of the voice coil 40 at that time. The displacement x was measured by laser as the displacement of a measuring piece 41 placed on the voice coil 40. 【0043】 Then, the magnitude of the restoring force K (=F / x) [g / mm] that causes the voice coil 40 pressed against the gauge 80 to return to its original position was evaluated as the strength of the centering effect. Using the first top plate 20 as a reference (33.4), the second top plate 20 was approximately 2.2 times (≒74.1 / 33.4), and the third top plate was approximately 1.9 times (≒64.0 / 33.4), confirming that the centering effect is higher in the top plate 20 equipped with the protrusion 60. 【0044】 In this case, as shown in Figure 13, for each model 100 (Rectangular top plate using the first top plate 20, Corrugated top plate using the second top plate 20, and Crenelated top plate using the third top plate 20), 50 points of displacement x (horizontal axis in the same figure) corresponding to the load F (vertical axis in the same figure) were measured, and the average value of the restoring force K based on these measurements was evaluated.

Claims

1. A speaker comprising: a magnet body extending in a predetermined direction and magnetized along this direction; a plate-shaped top plate disposed on one end face of the magnet body and extending along an intersecting surface that intersects the direction in which the magnet body extends; a yoke having a main body disposed on the other end face of the magnet body and extending along the intersecting surface, and a facing portion extending from the main body to a position facing the side surface of the top plate; a voice coil disposed in the magnetic gap between the side region of the top plate and the facing region of the facing portion facing this side region; a magnetic fluid interposed between the side region and the voice coil, or between the facing region and the voice coil; and a projection extending from either the side region or the facing region toward the other, wherein the projection is shorter in the direction in which the magnet body extends than the side region of the top plate and is provided around the entire circumference of the facing region.

2. The speaker according to claim 1, wherein the protrusion is a flange-shaped, single projection provided around the entire circumference of the opposing region.

3. The speaker according to claim 1, wherein the protruding portion is a plurality of projections arranged at predetermined intervals along the intersecting surface over the entire circumference of the opposing region.

4. The speaker according to any one of claims 1 to 3, wherein the top plate extends over a wider area than the magnet body in a plan view intersecting the direction in which the magnet body extends, the protrusion protrudes from the side region, the opposing portion is formed as a projection that extends to the side region over a wider area than the protrusion in the direction in which the magnet body extends, and the distance L1 from the surface of the top plate along the side region to one end face of the protrusion, the distance L2 from the back surface of the top plate along the side region to the other end face of the protrusion, the distance L3 from the other end of the side region along the back surface of the top plate to the magnet body, the distance L4 from the end of the protrusion on one end face to the end of the opposing region on one end face, the distance L5 from the end of the protrusion on the other end face to the end of the opposing region on the other end face, and the protrusion distance L6 from the side region of the protrusion are each configured to have the relationship shown in the following formula. L1, L2<L3 (Formula 1) L1, L2<L6 (Formula 2) L4, L5<L6 (Formula 3)

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