JP2013009036A - Outer magnet type magnetic circuit and dynamic speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology required for further reducing the thickness of a dynamic speaker.SOLUTION: A fixed side component 2 includes: a permanent magnet 4 formed into a circular ring shape; a frame 5 having a top plate 10 facing a north pole of the permanent magnet 4 and an L shaped part 11 formed so as to continue into the top plate 10; and a yoke 6 having a bottom plate 15 facing a south pole of the permanent magnet 4 and a center pole 16 formed so as to connect with the bottom plate 15. The L shaped part 11 is formed protruding to the bottom plate 15 side and the center pole 16 is formed protruding to the top plate 10 side. A magnetic gap G is formed between the L shaped part 11 and the center pole 16. In the L shaped part 11, only a first magnetic gap facing part 32, which is a tip part in the protruding direction, faces the center pole 16.

Description

  The present invention relates to an outer magnet type magnetic circuit and a dynamic speaker.

  As this type of technology, Patent Document 1 discloses a general outer magnet type magnetic circuit employed in a dynamic speaker. The outer magnet type magnetic circuit includes a top plate, a magnet, a bottom plate, and a center pole. A magnetic gap is formed between the top plate and the center pole, and a voice coil is arranged in the magnetic gap.

JP-A-8-9494

  The dynamic speaker of Patent Document 1 is required to be further thinned.

  Therefore, an object of the present invention is to provide a technology necessary for further thinning the dynamic speaker.

According to a first aspect of the present invention, the permanent magnet is formed in an annular shape, a first magnetic pole facing portion that faces the first magnetic pole of the permanent magnet, and the first magnetic pole facing portion. A first magnetic member having a first projecting portion, a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second projecting portion formed connected to the second magnetic pole facing portion. And the first protrusion is formed to protrude toward the second magnetic pole facing portion, and the second protrusion is on the first magnetic pole facing portion side. And a magnetic gap is formed between the first projecting portion and the second projecting portion, and the first projecting portion has only the second projecting portion in the projecting direction. An external magnetic type magnetic circuit is provided.
According to a second aspect of the present invention, the permanent magnet is formed in an annular shape, a first magnetic pole facing portion facing the first magnetic pole of the permanent magnet, and connected to the first magnetic pole facing portion. A first magnetic member having a first projecting portion, a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second projecting portion formed connected to the second magnetic pole facing portion. And the first protrusion is formed to protrude toward the second magnetic pole facing portion, and the second protrusion is on the first magnetic pole facing portion side. And a magnetic gap is formed between the first protrusion and the second protrusion, and the first protrusion is the first viewed from the first magnetic pole of the permanent magnet. An outer magnet type magnetic circuit including a magnetic flux bending portion for bending a magnetic flux so as to be substantially parallel to the direction of two magnetic poles. It is subjected.
According to a third aspect of the present invention, the permanent magnet is formed in an annular shape, a first magnetic pole facing portion that faces the first magnetic pole of the permanent magnet, and the first magnetic pole facing portion. A first magnetic member having a first projecting portion, a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second projecting portion formed connected to the second magnetic pole facing portion. And the first protrusion is formed to protrude toward the second magnetic pole facing portion, and the second protrusion is on the first magnetic pole facing portion side. A magnetic gap is formed between the first protrusion and the second protrusion, and a front end surface of the second protrusion in the protrusion direction is the first of the permanent magnet. In the direction of the second magnetic pole as viewed from the magnetic pole, the tip in the protruding direction of the first protruding portion Are located midway between the proximal end, an outer magnet type magnetic circuit is provided.
Further, the tip end surface in the protruding direction of the second protruding portion is in a positional relationship overlapping with the permanent magnet in the direction of the second magnetic pole as viewed from the first magnetic pole of the permanent magnet.
Moreover, a dynamic speaker provided with the above-described outer magnet type magnetic circuit is provided.

  If the outer magnet type magnetic circuit of the present invention is employed, the dynamic speaker can be made thinner.

FIG. 1 is a cross-sectional perspective view of a dynamic speaker employing an outer magnet type magnetic circuit. (First embodiment) FIG. 2 is a cross-sectional perspective view of the dynamic speaker shown in FIG. 1 with movable parts removed. (First embodiment) FIG. 3 is a longitudinal sectional view of FIG. (First embodiment) FIG. 4 is an enlarged vertical end view of the main part of FIG. (First embodiment) FIG. 5 is a diagram showing a typical magnetic flux path. (First embodiment) FIG. 6 is a diagram showing a typical magnetic flux path in a general outer magnet type magnetic circuit. (Comparative example) FIG. 7 is a cross-sectional perspective view of a dynamic speaker employing an external magnet type magnetic circuit. (Second Embodiment) FIG. 8 is an enlarged vertical end view of the main part of FIG. (Second Embodiment)

(First embodiment)
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS.

(Outer magnet type dynamic speaker 1)
As shown in FIGS. 1 and 2, the outer-magnet dynamic speaker 1 includes a fixed-side component 2 that constitutes an outer-magnet-type magnetic circuit, and a movable-side component 3 that is driven by the fixed-side component 2. Yes.

(General description of the fixed-side component 2)
As shown in FIG. 3, the stationary component 2 includes a permanent magnet 4 formed in an annular shape, a frame 5 (first magnetic member), and a yoke 6 (second magnetic member).

  First, with reference to FIG. 3, “axial direction”, “radiation direction”, “anti-radiation direction”, “radial direction”, “center direction”, and “anti-center direction” are defined. “Axial direction” means “the axial direction of the permanent magnet 4 specified as a direction perpendicularly penetrating the inner circumferential space of the permanent magnet 4 formed in an annular shape”. “Radiation direction” means “the axial direction in which sound waves generated by the external magnetic type dynamic speaker 1 are radiated toward the user”. The “anti-radiation direction” is “an axial direction opposite to the radiation direction”. The “radial direction” is a “direction perpendicular to the axial direction”. The “center direction” is “a radial direction, a direction from the outer peripheral side to the inner peripheral side of the permanent magnet 4 formed in an annular shape”. “Anti-center direction” is “a radial direction, a direction from the inner circumference side to the outer circumference side of the permanent magnet 4 formed in an annular shape”.

(Fixed side part 2: Permanent magnet 4)
As shown in FIG. 3, the permanent magnet 4 is magnetized so that the radial direction side is an N pole (first magnetic pole) and the antiradiating direction side is an S pole (second magnetic pole).

(Fixed side part 2: Frame 5)
The frame 5 serves as a part of the outer magnet type magnetic circuit and elastically supports the movable part 3. The frame 5 is made of a magnetic material, and includes a top plate 10 (first magnetic pole facing portion), an L-shaped portion 11 (first projecting portion), and a diaphragm holding portion 12.

  The top plate 10 faces the north pole of the permanent magnet 4.

  The L-shaped part 11 is formed so as to protrude in the anti-radiation direction by being connected to the inner peripheral end of the top plate 10 and bending in an L-shape. In other words, the L-shaped portion 11 is formed so as to protrude into the inner circumferential space of the permanent magnet 4.

  The diaphragm holding portion 12 is connected to the outer peripheral end of the top plate 10 and is formed to protrude in the radial direction.

(Fixed side part 2: yoke 6)
The yoke 6 bears a part of the outer magnet type magnetic circuit. The yoke 6 is made of a magnetic material and includes a bottom plate 15 (second magnetic pole facing portion) and a center pole 16 (second projecting portion).

  The bottom plate 15 faces the south pole of the permanent magnet 4.

  The center pole 16 is connected to the bottom plate 15 and protrudes in the radial direction. In other words, the center pole 16 is formed to protrude so as to enter the inner circumferential space of the permanent magnet 4.

(Magnetic gap G)
The L-shaped part 11 and the center pole 16 are partially opposed in the radial direction. The L-shaped part 11 is arranged on the outer peripheral side with respect to the center pole 16. A magnetic gap G is formed between the L-shaped part 11 and the bottom plate 15.

(Moving side part 3)
The movable part 3 includes a voice coil bobbin 20, a diaphragm 21, and a center cap 22.

  The voice coil bobbin 20 is a thin cylindrical body, and is elastically supported by the frame 5 by a silicon damper (not shown). A voice coil 23 is formed at the end of the voice coil bobbin 20.

  The diaphragm 21 is supported by the voice coil bobbin 20 and the frame 5.

  The center cap 22 is bonded to the diaphragm 21 so as to cover the voice coil bobbin 20.

  With the above configuration, the voice coil 23 of the voice coil bobbin 20 of the movable part 3 is positioned so as to overlap the magnetic gap G of the fixed part 2. When a desired audio signal is supplied to the voice coil 23 in this state, the voice coil 23 vibrates according to Fleming's left hand rule, and the vibration causes the voice coil bobbin 20 to vibrate along with the diaphragm 21 in the axial direction. A desired sound wave is radiated from 21 toward the user.

(Detailed explanation of the fixed part 2)
Next, the structure of the stationary part 2 will be described in detail with reference to FIG. In FIG. 4, hatching indicating a cross section is omitted for convenience of explanation.

  As shown in FIG. 4, the L-shaped portion 11 includes an extension portion 30, a magnetic flux bending portion 31, and a first magnetic gap facing portion 32 (tip portion). In FIG. 4, the top plate 10, the extension portion 30, the magnetic flux bending portion 31, and the first magnetic gap are shown in order to clarify the ranges occupied by the top plate 10, the extension portion 30, the magnetic flux bending portion 31, and the first magnetic gap facing portion 32. Each of the facing portions 32 is represented by a two-dot chain line.

  The extension 30 is connected to the top plate 10 and extends in the center direction.

  The magnetic flux bending portion 31 bends the magnetic flux in the L-shaped portion 11 of the frame 5 so that the magnetic flux in the L-shaped portion 11 of the frame 5 is substantially parallel to the axial direction. The magnetic flux bending part 31 is connected to the extension part 30 and is smoothly bent approximately 90 degrees on the side opposite to the radiation direction.

  The first magnetic gap facing portion 32 is connected to the magnetic flux bending portion 31 and extends in the antiradiation direction. The first magnetic gap facing portion 32 corresponds to the tip portion in the protruding direction of the L-shaped portion 11. As shown in FIG. 4, only the first magnetic gap facing portion 32 of the L-shaped portion 11 faces the center pole 16 of the yoke 6. In other words, the distal end surface 16a in the radial direction of the center pole 16 is located midway between the distal end P and the proximal end Q in the protruding direction of the L-shaped portion 11 in the axial direction. Specifically, the distal end surface 40a in the radial direction of the second magnetic gap facing portion 40 as the portion facing the L-shaped portion 11 of the center pole 16 is based on the distal end P in the protruding direction of the L-shaped portion 11 in the axial direction. Located halfway between the ends Q. More specifically, the tip surface 40a of the second magnetic gap facing portion 40 of the center pole 16 is in a positional relationship overlapping with the permanent magnet 4 in the axial direction.

(Magnetic flux path)
Next, the path of the magnetic flux φ in the stationary part 2 will be described with reference to FIG. In FIG. 5, for convenience of explanation, a typical magnetic flux φ starting from the N pole of the permanent magnet 4 and ending at the S pole is represented by three thick lines.

  As shown in FIG. 5, the magnetic flux φ starting from the north pole of the permanent magnet 4 in the radial direction enters the top plate 10. The magnetic flux φ is bent approximately 90 degrees in the top plate 10 so as to go in the center direction, and enters the extension 30 of the L-shaped part 11. The magnetic flux φ goes straight in the center direction in the extension portion 30 and enters the magnetic flux bending portion 31. The magnetic flux φ is bent by approximately 90 degrees so as to go in the anti-radiation direction in the magnetic flux bending portion 31 and enters the first magnetic gap facing portion 32. The magnetic flux φ is bent by approximately 90 degrees again in the first magnetic gap facing portion 32 and directed toward the central direction, and is guided to the magnetic gap G. The magnetic flux φ forms an extremely high magnetic flux density in the magnetic gap G, and an effective magnetic field acts on the voice coil 23 indicated by a two-dot chain line. When the magnetic flux φ passes through the magnetic gap G, it enters the second magnetic gap facing portion 40 of the center pole 16. Thereafter, the magnetic flux φ ends at the S pole of the permanent magnet 4 via the bottom plate 15.

  Next, the technical significance of the path of the magnetic flux φ shown in FIG. 5 will be described with reference to FIG. FIG. 6 shows a general outer magnet type magnetic circuit. In FIG. 6, members corresponding to those in FIG. 5 are given the same reference numerals.

  As shown in FIG. 6, in the outer magnet type magnetic circuit, the magnetic flux φ starting from the N pole of the permanent magnet 4 in the radial direction enters the top plate 10. The magnetic flux φ is bent approximately 90 degrees in the top plate 10 toward the center. The magnetic flux φ travels straight in the center direction in the top plate 10 and is guided to the magnetic gap G. The magnetic flux φ forms an extremely high magnetic flux density in the magnetic gap G, and an effective magnetic field acts on the voice coil 23 indicated by a two-dot chain line. When the magnetic flux φ passes through the magnetic gap G, it enters the center pole 16. Thereafter, the magnetic flux φ ends at the S pole of the permanent magnet 4 via the bottom plate 15.

  Next, when the magnetic gap G in FIG. 5 is compared with the magnetic gap G in FIG. 6, almost the same magnetic flux density distribution is formed in any magnetic gap G. However, the magnetic gap G in FIG. 5 is closer to the bottom plate 15 in the axial direction than the magnetic gap G in FIG. The fact that the magnetic gap G is close to the bottom plate 15 in the axial direction means that the voice coil 23 of the voice coil bobbin 20 of the movable part 3 can be brought close to the bottom plate 15 in the axial direction as shown in FIG. . The fact that the voice coil 23 of the voice coil bobbin 20 of the movable part 3 is brought close to the bottom plate 15 in the axial direction means that the movable part 3 is brought close to the bottom plate 15 as a whole in the axial direction. . This contributes to thinning of the outer-magnet dynamic speaker 1 in the axial direction.

  Instead of bringing the magnetic gap G close to the bottom plate 15 in the axial direction, for example, when the diaphragm 21 is bonded to the voice coil bobbin 20 in FIG. Thinning in the axial direction of the dynamic speaker 1 can be achieved. However, according to the knowledge of the inventors of the present application, the change in the shape of the movable part 3 is directly connected to the deterioration of sound quality, and it is not possible to achieve thinning until the sound quality is deteriorated. The priority is reversed as the design concept of the magnetic dynamic speaker 1. In this sense, it can be mentioned that the technical idea mainly shown in FIG. 5 has a technical significance that should be noted in that the thinning of the outer-magnet dynamic speaker 1 can be achieved without deteriorating the sound quality. .

  Although the first embodiment of the present invention has been described above, the stationary part 2 of the present embodiment has the following features in short.

  That is, the stationary component 2 (outer magnet type magnetic circuit) includes an annular permanent magnet 4 and a top plate 10 (first magnetic pole facing portion) that faces the N pole (first magnetic pole) of the permanent magnet 4. And a frame 5 (first magnetic member) having an L-shaped part 11 (first projecting part) formed by being connected to the top plate 10, and an S pole (second magnetic pole) of the permanent magnet 4. The yoke 6 (2nd magnetic member) which has the bottom plate 15 (2nd magnetic pole opposing part) and the center pole 16 (2nd protrusion part) formed in connection with the bottom plate 15 is provided. The L-shaped part 11 is formed so as to protrude toward the bottom plate 15 side (that is, in the anti-radiation direction). The center pole 16 is formed to protrude toward the top plate 10 (that is, in the radial direction). A magnetic gap G is formed between the L-shaped part 11 and the center pole 16. In the L-shaped portion 11, only the first magnetic gap facing portion 32 as the tip portion in the protruding direction faces the center pole 16. According to the above characteristics, as shown in FIG. 5, the magnetic gap G is formed at a position close to the bottom plate 15 in the axial direction, so that the outer magnet type dynamic speaker 1 is thinned in the axial direction. Contribute to.

  In other words, the L-shaped portion 11 includes a magnetic flux bending portion 31 that bends the magnetic flux φ so as to be substantially parallel to the axial direction. Also with the above characteristics, as shown in FIG. 5, the magnetic gap G is formed at a position close to the bottom plate 15 in the axial direction, so that the outer-magnet dynamic speaker 1 can be thinned in the axial direction. Contribute.

  In other words, the distal end surface 16a in the projecting direction of the center pole 16 is located midway between the distal end P and the proximal end Q in the projecting direction of the L-shaped portion 11 in the axial direction. . Also with the above characteristics, as shown in FIG. 5, the magnetic gap G is formed at a position close to the bottom plate 15 in the axial direction, so that the outer-magnet dynamic speaker 1 can be thinned in the axial direction. Contribute.

  The first embodiment described above can be modified as follows, for example.

  That is, as shown in FIG. 3, the top plate 10 and the L-shaped part 11 are integrated, but instead, the top plate 10 and the L-shaped part 11 may be separate parts. Similarly, the bottom plate 15 and the center pole 16 are integrated, but instead, the bottom plate 15 and the center pole 16 may be separate parts.

  In FIG. 3, a metal plate for avoiding magnetic saturation of the top plate 10 may be separately inserted between the top plate 10 and the permanent magnet 4.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the present embodiment will be described with a focus on differences from the first embodiment, and overlapping descriptions will be omitted as appropriate. In addition, in principle, the same reference numerals are assigned to components corresponding to the respective components of the first embodiment.

(Outer magnet type dynamic speaker 1)
As shown in FIG. 7, the external magnetic type dynamic speaker 1 according to the present embodiment is similar to the first embodiment in that the fixed side component 2 constituting the external magnetic type magnetic circuit and the movable side driven by the fixed side component 2 The component 3 is comprised.

(Fixed side part 2: Frame 5)
The frame 5 has an S-shaped portion 50 (first projecting portion) instead of the L-shaped portion 11 (see also FIG. 5).

  The S-shaped portion 50 is connected to the inner peripheral end of the top plate 10 and is formed to protrude in the anti-radiation direction while being bent in an S-shape. In other words, the S-shaped portion 50 is formed to protrude so as to enter the inner circumferential space of the permanent magnet 4.

(Magnetic gap G)
The S-shaped part 50 and the center pole 16 are partially opposed in the radial direction, and a magnetic gap G is formed between them.

  As shown in FIG. 8, the S-shaped portion 50 is configured by a first magnetic flux bending portion 51 and a second magnetic flux bending portion 52 (tip portion). In FIG. 8, the top plate 10, the first magnetic flux bending portion 51, and the second magnetic flux bending portion 52 are each laid out in order to clarify the range occupied by the top plate 10, the first magnetic flux bending portion 51, and the second magnetic flux bending portion 52. Expressed with a dotted line.

  The first magnetic flux bending portion 51 is connected to the top plate 10 and is smoothly bent approximately 90 degrees on the side opposite to the radiation direction.

  The second magnetic flux bending portion 52 is connected to the first magnetic flux bending portion 51 and is formed by smoothly bending approximately 90 degrees toward the center direction.

  As shown in FIG. 8, only the second magnetic flux bending portion 52 of the S-shaped portion 50 faces the center pole 16 of the yoke 6. In other words, the distal end surface 16a in the radial direction of the center pole 16 is located midway between the distal end P and the proximal end Q in the protruding direction of the S-shaped portion 50 in the axial direction. Specifically, the distal end surface 40a in the radial direction of the second magnetic gap facing portion 40 as a portion facing the S-shaped portion 50 of the center pole 16 is based on the distal end P in the protruding direction of the S-shaped portion 50 in the axial direction. Located halfway between end Q. More specifically, the tip surface 40a of the second magnetic gap facing portion 40 of the center pole 16 is in a positional relationship overlapping with the permanent magnet 4 in the axial direction.

  The configuration shown in FIG. 8 also exhibits exactly the same effect as the technical significance of the path of the magnetic flux φ shown in FIG. That is, by adopting the configuration of FIG. 8, it contributes to thinning of the outer magnet type dynamic speaker 1 in the axial direction.

DESCRIPTION OF SYMBOLS 1 External magnet type dynamic speaker 2 Fixed side part 3 Movable side part 4 Permanent magnet 5 Frame 6 Yoke 10 Top plate 11 L-shaped part 15 Bottom plate 16 Center pole
G Magnetic gap

Claims (5)

A permanent magnet formed in an annular shape;
A first magnetic member having a first magnetic pole facing portion facing the first magnetic pole of the permanent magnet, and a first protrusion formed connected to the first magnetic pole facing portion;
A second magnetic member having a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second protrusion formed connected to the second magnetic pole facing portion;
With
The first protrusion is formed to protrude toward the second magnetic pole facing part, and the second protrusion is formed to protrude toward the first magnetic pole facing part.
A magnetic gap is formed between the first protrusion and the second protrusion;
The first protrusion has only the tip in the protruding direction facing the second protrusion.
External magnetic circuit. A permanent magnet formed in an annular shape;
A first magnetic member having a first magnetic pole facing portion facing the first magnetic pole of the permanent magnet, and a first protrusion formed connected to the first magnetic pole facing portion;
A second magnetic member having a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second protrusion formed connected to the second magnetic pole facing portion;
With
The first protrusion is formed to protrude toward the second magnetic pole facing part, and the second protrusion is formed to protrude toward the first magnetic pole facing part.
A magnetic gap is formed between the first protrusion and the second protrusion;
The first protrusion includes a magnetic flux bending portion that bends the magnetic flux so as to be substantially parallel to the direction of the second magnetic pole as viewed from the first magnetic pole of the permanent magnet.
External magnetic circuit. A permanent magnet formed in an annular shape;
A first magnetic member having a first magnetic pole facing portion facing the first magnetic pole of the permanent magnet, and a first protrusion formed connected to the first magnetic pole facing portion;
A second magnetic member having a second magnetic pole facing portion facing the second magnetic pole of the permanent magnet, and a second protrusion formed connected to the second magnetic pole facing portion;
With
The first protrusion is formed to protrude toward the second magnetic pole facing part, and the second protrusion is formed to protrude toward the first magnetic pole facing part.
A magnetic gap is formed between the first protrusion and the second protrusion;
The distal end surface in the projecting direction of the second projecting portion is halfway between the distal end and the proximal end in the projecting direction of the first projecting portion in the direction of the second magnetic pole as viewed from the first magnetic pole of the permanent magnet. positioned,
External magnetic circuit. The outer magnet type magnetic circuit according to claim 3,
The tip surface in the protruding direction of the second protruding portion is in a positional relationship overlapping with the permanent magnet in the direction of the second magnetic pole as viewed from the first magnetic pole of the permanent magnet.
External magnetic circuit. A dynamic speaker comprising the outer magnet type magnetic circuit according to claim 1.

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