JP2577561Y2 - Magnetic circuit for speaker - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a loudspeaker having an annular magnetic air gap formed by combining two annular radial anisotropic magnets having large and small diameters so as not to be exposed to the outside air. It relates to a magnetic circuit.

[0002]

2. Description of the Related Art Conventionally, this type of speaker magnetic circuit includes:
As shown in FIG. 3, there is one disclosed in Japanese Utility Model Laid-Open No. 63-163097.

[0003]

Therefore, as shown in FIG. 3 and described with reference to FIGS. 4 and 5, in a conventional magnetic circuit for a speaker of this kind, it is fitted into a yoke (4 '). Radial anisotropic rare earth Nd-Fe-B magnets (1a), (1b)
The surface of the magnetic gap (6 ') is exposed on the inner wall surface and the upper surface, so the surface is oxidized, and the corners are fragile, so it is easy to be broken. It must be protected by a thin film deposition process. However, this protective film is not preferable because the gap between the magnet and the magnetic body increases.

In the case where the magnets (1a) and (1b) are directly opposed to each other to form a magnetic gap (6 ') as described above,
If the radial dimensions (Δφi, Δφo) of (1a) and (1b) are small, a leakage magnetic flux (φι) whose direction is not equal to that of the main magnetic flux near the lower end of the gap is generated in the closely-contacted magnetic body, and FIG. As shown in (1), the usage efficiency of the magnets (1a) and (1b) is reduced. As a countermeasure for this, the radial dimensions of the magnets (1a) and (1b) (Δ
φi, Δφo) must be long (flat), and the magnetic resistance of the main magnetic path increases, resulting in the magnetic flux in the main magnetic path.
As the (φm) number decreases, the magnets far from the magnetic air gap (6 ′) do not contribute to the improvement of the magnetic flux density in the air gap (6 ′),
There is a problem that the use efficiency of the magnets (1a) and (1b) is reduced due to waste (see FIG. 4).

Therefore, the present invention is to solve the problems of the conventional speaker magnetic circuits (1e), (1f) and (1g) as shown in FIGS. 3, 4 and 5. , As shown in FIG.
Using the non-magnetic internal cap (5), using the annular pole pieces (8), (9), the non-magnetic upper plate (10),
By using (11), the surfaces of the magnets (6) and (7) are not exposed, and the difference (Δφi, Δφo) between the inner and outer diameters of the magnets (6) and (7) is reduced. Higher height (in a cylindrical shape)
It is an object of the present invention to provide a speaker magnetic circuit (1) that can eliminate waste of the magnets (6) and (7).

[0006]

The structure of the present invention for achieving the object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment. The present invention provides an annular magnetic air gap (2). In the magnetic circuits (1) and (1 ') to be constituted, a concave portion (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3) is formed, and a magnetic gap is formed at the bottom thereof.
An annular non-magnetic inner cap (5) provided with a spacer (5a) forming (2) is fitted therein, and an annular radial anisotropic magnet (6) having large and small diameters is fitted thereon. , (7), the yoke
The inner wall surface (6a) of (4) and the outer surface (7b) of the center magnetic pole (3) are fitted so as to be in contact with each other, and the magnet (6)
The annular magnetic pole pieces (8) and (9) contact the inner wall surface (6b) of the center hole and the outer wall surface (7a) of the magnet (7), respectively.
(2) A speaker magnetic circuit (1) having a structure in which the upper surface is covered with non-magnetic upper plates (10) and (11) having a flat plate annular shape.

[0007]

[Function] Since the present invention has such a structure, oxidation is prevented by a magnetic material covering the inner and outer surfaces of the magnet and a non-magnetic material such as copper, aluminum and resin covering the upper and lower surfaces. Can maintain impact resistance. Also, the facing surfaces of the magnets (6) and (7)
The annular magnetic pole pieces (8) and (9) used for the (magnetic gap magnetic wall surface) reduce the leakage flux and reduce the difference between the magnet inner and outer diameters (Δφi, Δ
φo) can be reduced and the height can be increased (in the form of a cylinder), which can eliminate wasted magnets. Further, by providing the annular groove (5b) as shown in FIG. 2, the contact of the voice coil at the time of large amplitude can be eliminated. That is, the outer peripheral surface of the magnet (6) is the outer wall of the yoke (4), and the inner peripheral surface of the magnet (7) is the central magnetic pole.
Since each part is covered with (3), if the dimensions of each part are accurate, the dimensions of the gap (2) can be maintained accurately. As described above, since the lower surfaces of both magnets (6) and (7) are in contact with the inner cap (5) of the non-magnetic material, it becomes difficult for the leakage magnetic flux to flow, and the dimensions of the magnets (6) and (7) are accordingly reduced. Can be taken high. In addition, current distortion is reduced by acting as a short ring by using a nonmagnetic conductor such as aluminum or brass for the inner cap (5) and the flat annular upper plates (10) and (11). .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing one embodiment of the present invention, and FIG. 1 is a half sectional view in the axial direction of the embodiment of the present invention. According to the present invention, in a magnetic circuit (1), (1 ′) constituting an annular magnetic air gap (2), a concave portion (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3) is formed, and a bottom portion thereof is formed. An annular non-magnetic internal cap (5) provided with a spacer (5a) for forming a magnetic air gap (2) is fitted therein, and an annular radial anisotropy having large and small diameters is fitted thereon. Use magnets (6) and (7)
The inner wall surface (6a) of (4) and the outer surface (7b) of the center magnetic pole (3) are fitted so as to be in contact with each other, and the magnet (6)
The annular magnetic pole pieces (8) and (9) contact the inner wall surface (6b) of the center hole and the outer wall surface (7a) of the magnet (7), respectively.
(2) A speaker magnetic circuit (1) having a structure in which the upper surface is covered with non-magnetic upper plates (10) and (11) having a flat plate annular shape.

Further, by removing the convex portion spacer (5a) of the inner cap (5) and replacing it with the annular groove (5b) of the inner cap (15) as shown in FIG. The contact of the voice coil can be eliminated. That is, since the outer periphery of the magnet (6) is covered by the outer wall of the yoke (4), if the dimensions of each component are accurate, the gap is not required even without the convex partial spacer (5a) of the inner cap (5). The dimensions can be retained. As described above, since the internal cap (5) is a non-magnetic material, it is difficult for the leakage magnetic flux to flow, and accordingly, the dimensions of the magnets (6) and (7) can be made higher.

Although the embodiments which are considered to be representative of the present invention have been described above, the present invention is not necessarily limited to only the structure of the embodiments, but has the above-mentioned constitutional requirements according to the present invention, and The present invention achieves the object of the present invention and can be appropriately modified and implemented within a range having the following effects.

[0011]

[Effects of the Invention] As is clear from the above description, the present invention provides a magnetic circuit (1),
In (1 ′), an annular portion in which a recess (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3) is formed, and a spacer (5a) for forming a magnetic gap (2) is provided at the bottom thereof. Non-magnetic internal cap
(5), and annular radial anisotropic magnets (6) and (7) having large and small diameters are placed on the inner wall surface (6a) of the yoke (4).
And the outer surface (7b) of the center magnetic pole (3) so as to abut against each other, and the inner wall surface (6b) of the center hole of the magnet (6) and the outer wall surface (7a) of the magnet (7) ) Are provided with annular magnetic pole pieces (8) and (9) to form magnetic gaps (2), and the upper plate (1)
0) and (11) are speaker magnetic circuits (1) having a structure covered by (11). Since the present invention is a magnetic circuit for a speaker having the above structure, the magnets (6) and (7) have inner and outer surfaces made of a magnetic material, and upper and lower surfaces made of a non-magnetic material such as copper, aluminum, or resin. Since it is covered with a magnetic material, oxidation can be prevented, and there is no loss due to impact or the like. Therefore, the magnetic circuit for the speaker of the present invention uses the annular magnetic poles as the magnets (6) and (7).
By using on the opposing surface (magnetic gap magnetic wall surface), the leakage magnetic flux is reduced, and the difference between the inner and outer diameters of the magnet (Δφi, Δφo) is reduced,
The height can be increased (in the form of a cylinder), and waste of magnets can be eliminated.

Further, the convex portion spacer (5a) of the inner cap (5) is removed, and as shown in FIG.
By setting b), it is possible to eliminate a voice coil contact accident at the time of large amplitude. That is, since the outer periphery of the magnet (6) is covered by the outer wall of the yoke (4), if the dimensions of each component are accurate, the convex partial spacer (5a) of the inner cap (5)
The gap size can be maintained even without the above. As described above, since the internal cap (5) is a non-magnetic material, it is difficult for the leakage magnetic flux to flow, and accordingly, the dimensions of the magnets (6) and (7) can be made higher. Internal cap (5), flat toroidal upper plate (10),
By using (11) as a non-magnetic conductor, it can function as a short ring, thereby reducing current distortion. Various remarkable effects in practical use can be expected.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional example.

FIG. 4 is an explanatory sectional view of a conventional example.

FIG. 5 is another explanatory sectional view of a conventional example.

[Explanation of symbols]

 (1) Magnetic circuit (2) Magnetic gap (3) Central pole (4) Bowl-shaped yoke (4a) Concave (5) Internal cap (5a) Spacer (6) Radial anisotropic magnet (6a) Center hole outer surface (7 ) Radial anisotropic magnet (7b) Inner surface of center hole (8) Pole piece (9) Pole piece (10) Upper plate (11) Upper plate

Claims (1)

(57) [Scope of request for utility model registration] 1. A magnetic circuit (1) constituting an annular magnetic air gap (2), a recess (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3) is formed, and a magnetic air gap is formed at the bottom thereof. An annular inner cap (5) provided with a spacer (5a) forming (2) is fitted, and an annular radial anisotropic magnet (6), (7) having a large or small diameter is fitted thereon. And the inner surface of the yoke (4) and the outer surface of the center magnetic pole (3) are fitted and fitted together, and the magnet (6)
The inner surface (6b) of the center hole and the outer surface (7a) of the magnet (7)
The magnetic pole pieces (8) and (9) are provided so as to abut each other to form a magnetic gap (1), and the upper surface is covered with a flat annular upper plate (10) and (11). Circuit (1).