JPH0555694U - Magnetic circuit for speaker - Google Patents

Abstract

(57) [Summary] [Purpose] Non-magnetic internal cap, annular pole piece,
By using the non-magnetic upper plate, the surface of the magnet is not exposed, and the difference in the inner and outer diameters of the magnet is made small, and the height is made high (cylindrical) to waste the magnet. lose. [Structure] In a magnetic circuit forming an annular magnetic gap, a concave portion of a bowl-shaped yoke having a central magnetic pole is formed, and an inner cap of an annular non-magnetic body is provided at the bottom thereof with a spacer forming a magnetic gap. The ring-shaped radial anisotropic magnets having large and small diameters are fitted on the inner wall surface of the yoke and the outer surface of the central magnetic pole so that they are abutted, respectively, and A magnetic pole is formed by making contact with the inner wall of the center hole and the outer wall of the magnet to form a magnetic gap, and the top surface is covered with a flat plate-shaped non-magnetic upper plate.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a magnetic circuit for a speaker in which an outer surface of two annular radial anisotropic magnets having large and small diameters are combined so as not to be exposed to the outside air to form an annular magnetic gap. ..

[0002]

[Prior Art]

 A conventional magnetic circuit for a speaker of this type is disclosed in Japanese Utility Model Laid-Open No. 63-163097, as shown in FIG.

[0003]

[Problems to be solved by the device]

 Therefore, as shown in FIG. 3 and described with reference to FIGS. 4 and 5, in the conventional magnetic circuit for the speaker of this type, the radial anisotropic rare earth Nd-Fe- which is fitted in the yoke (4 '). The surfaces of the B magnets (1a) and (1b) are exposed at the inner wall surface and the upper surface of the magnetic gap (6 '), so that the surfaces are oxidized and the corners are fragile, so they are easily damaged. As a countermeasure, the surface must be protected by applying a thin film deposition process such as plating. However, this protective film is not preferable because it increases the gap between the magnet and the magnetic body.

Further, when the magnets (1a) and (1b) are directly opposed to each other to form the magnetic gap (6 ′) as described above, the radial dimension of the magnets (1a) and (1b) When (Δφi, Δφo) is small, leakage flux (φι) whose direction is not the same as that of the main magnetic flux is generated in the close magnetic body near the lower end of the air gap, and as shown in Fig. 4, the magnets (1a), ( Reduces the usage efficiency of 1b). As a measure against this, make the radial dimensions (Δφi, Δφo) of the magnets (1a), (1b) long (flat) so that the influence of the magnetic pole on the side opposite to the air gap (6 ') can be ignored. The magnetic resistance of the main magnetic path increases, resulting in a decrease in the number of magnetic fluxes (φm) in the main magnetic path. There is a problem that it does not contribute to the improvement of the magnetic flux density in 6 ') and is wasted, and the usage efficiency of the magnets (1a), (1b) decreases (see Fig. 4).

Therefore, the present invention aims to solve the problems of the conventional magnetic circuits for speakers (1e), (1f), and (1g) as shown in FIGS. 3, 4, and 5. As shown in Fig. 1, the inner cap (5) of non-magnetic material is used, the annular pole pieces (8), (9) are used, and the upper plate (10), (11) of non-magnetic material is used. To prevent the surfaces of the magnets (6) and (7) from being exposed, and to reduce the difference between the inner and outer diameters of the magnets (6) and (7) (Δφi, Δφo), It is intended to provide a magnetic circuit (1) for a loudspeaker in which the height of the magnet (cylindrical) can be increased to eliminate waste of the magnets (6) and (7).

[0006]

[Means for Solving the Problems]

 The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 and 2 corresponding to the embodiment. The present invention shows that the magnetic circuit (1), ( 1 ') forms a recess (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3), and a spacer (5a) that forms a magnetic gap (2) at the bottom of the recess (4a) Insert the inner cap (5) of the non-magnetic material of the above, and place the annular radial anisotropic magnets (6), (7) having large and small diameters on the inner cap (6a) of the yoke (4). ) And the outer surface (7b) of the central magnetic pole (3) so as to be in contact with each other, and are fitted together, and the inner wall surface (6b) of the center hole of the magnet (6) and the outer wall surface of the magnet (7) ( The magnetic poles (8) and (9), which are respectively in contact with (7a), are provided to form the magnetic gap (2), and the upper surface is made of a non-magnetic upper plate (10), (11) having a flat plate annular shape. This is a magnetic circuit for a speaker (1) with a structure covered with).

[0007]

[Action]

 Since the present invention has such a structure, the magnetic material that covers the inner and outer surfaces of the magnet and the non-magnetic material that covers the upper and lower surfaces, such as copper, aluminum, and resin, prevent oxidation and impact resistance. Can hold. In addition, the annular magnetic pole pieces (8) and (9) used on the facing surfaces (magnetic gap magnetic wall surfaces) of the magnets (6) and (7) reduce the leakage flux, and the difference between the inner and outer diameters of the magnet (Δφi , Δφo) can be made small and the height can be made high (cylindrical), and the waste of the magnet can be eliminated. Further, by providing the annular groove (5b) as shown in FIG. 2, it is possible to eliminate the contact of the voice coil when the amplitude is large. That is, since the outer peripheral surface of the magnet (6) is covered by the outer wall of the yoke (4) and the inner peripheral surface of the magnet (7) is covered by the central magnetic pole (3), the dimensions of each part must be accurate. For example, the dimensions of the void (2) can be maintained accurately. In this way, since the lower surfaces of both magnets (6) and (7) are in contact with the internal cap (5) of the non-magnetic material, it becomes difficult for leakage flux to flow, and the dimensions of magnets (6) and (7) are reduced accordingly. It can be taken high. In addition, by making the inner cap (5) and the plate-shaped annular upper plates (10), (11) non-magnetic conductors such as aluminum and brass, they act as a short ring, which causes current distortion. Reduce.

[0008]

【Example】

 An embodiment 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 an axial half sectional view of the embodiment of the present invention. The present invention forms a concave portion (4a) of a bowl-shaped yoke (4) having a central magnetic pole (3) in the magnetic circuits (1) and (1 ') forming the annular magnetic gap (2), and A circular non-magnetic inner cap (5) with a spacer (5a) that forms a magnetic gap (2) is inserted in the bottom, and a circular radial anisotropic shape with large and small diameters is placed on it. The magnetic magnets (6) and (7) to the inner wall surface (6a) of the yoke (4) and the outer surface (7b) of the central magnetic pole (3), respectively, so that they abut, and A magnetic air gap (2) is formed by providing circular magnetic pole pieces (8), (9) that contact the inner wall surface (6b) of the center hole of the magnet (6) and the outer wall surface (7a) of the magnet (7), respectively. At the same time, the speaker magnetic circuit (1) has a structure in which the upper surface is covered with a flat plate annular non-magnetic upper plate (10), (11).

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 circumference of the magnet (6) is covered by the outer wall of the yoke (4), if the dimensions of each component are correct, the convex cap spacer (5a) of the internal cap (5) may be omitted. Void size can be maintained. As described above, since the inner cap (5) is made of a non-magnetic material, it becomes difficult for leakage magnetic flux to flow, and accordingly, the dimensions of the magnets (6) and (7) can be increased.

Although the embodiments considered to be typical of the present invention have been described above, the present invention is not necessarily limited to the structures of these embodiments, and is provided with the above-mentioned structural requirements of the present invention, and The present invention can be carried out with appropriate modifications within the scope of achieving the object of the present invention and having the following effects.

[0011]

[Effect of the device]

 As is apparent from the above description, the present invention provides a bowl-shaped yoke (4) having a central magnetic pole (3) in the magnetic circuits (1) and (1 ') constituting the annular magnetic gap (2). Concave part (4a) is formed, and the bottom of the concave part (4a) is fitted with an inner cap (5) of an annular non-magnetic material provided with a spacer (5a) that forms a magnetic gap (2). Make sure that the annular radial anisotropic magnets (6) and (7) with the diameter of are contacted with the inner wall surface (6a) of the yoke (4) and the outer surface (7b) of the central magnetic pole (3), respectively. The ring-shaped magnetic pole pieces (8) and (9) that are fitted to the inner wall surface (6b) of the center hole of the magnet (6) and the outer wall surface (7a) of the magnet (7). The speaker magnetic circuit (1) has a structure in which a magnetic air gap (2) is provided and the upper surface is covered with a flat plate annular non-magnetic upper plate (10), (11). Since the present invention is the speaker magnetic circuit having the above-described structure, the magnets (6) and (7) are made of a magnetic material on the inner and outer surfaces thereof, and the upper and lower surfaces thereof are made of a non-magnetic material such as copper, aluminum or resin. Since it is covered with a magnetic material, it can prevent oxidation and will not be damaged by impact. Therefore, in the speaker magnetic circuit of the present invention, by using the annular magnetic poles on the facing surfaces (magnetic gap magnetic wall surfaces) of the magnets (6) and (7), the leakage magnetic flux is reduced and the inner and outer diameters of the magnet are reduced. The difference (Δφi, Δφo) can be made small and the height can be made high (cylindrical), and the waste of the magnet can be eliminated.

Further, by removing the convex portion spacer (5a) of the inner cap (5) and replacing it with an annular groove (5b) as shown in FIG. 3, a voice coil contact accident at a large amplitude can be prevented. It can be lost. That is, since the outer circumference of the magnet (6) is covered by the outer wall of the yoke (4), if the dimensions of each part are correct, the gap will not be present even if the convex cap spacer (5a) of the inner cap (5) is not present. Dimensions can be retained. In this way, since the inner cap (5) is made of a non-magnetic material, it becomes difficult for leakage magnetic flux to flow, and the dimensions of the magnets (6), (7) can be increased accordingly. By making the inner cap (5) and the plate-shaped annular upper plates (10), (11) non-magnetic conductors, which act as short rings, current distortion can be reduced. It has come to be possible to expect remarkable effects in various practical applications.

[Brief description of drawings]

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

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

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

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

FIG. 5 is another explanatory cross-sectional view of the conventional example.

[Explanation of symbols]

 (1) Magnetic circuit (2) Magnetic air gap (3) Central magnetic pole (4) Bowl-shaped yoke (4a) Recess (5) Inner 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) Top plate (11) Top plate

Claims (1)

[Scope of utility model registration request] 1. A magnetic circuit constituting an annular magnetic gap (2).
In (1), the inner portion of the annular shape in which the recess (4a) of the bowl-shaped yoke (4) having the central magnetic pole (3) is formed, and the spacer (5a) forming the magnetic gap (2) is provided at the bottom of the recess (4a). Insert the cap (5), and then insert the annular radial anisotropic magnets (6) and (7) having large and small diameters onto the inner surface of the yoke (4) and the central magnetic pole (3).
Combine and fit so that they contact the outer surfaces of
Also, the outer surface (6a) and inner surface (7b) of the center holes of both magnets (6), (7)
The magnetic poles (8) and (9) that come into contact with the magnetic poles (8) and (9), respectively, are provided to form the magnetic gap (2), and the top surface is covered with the flat ring-shaped upper plates (10) and (11). Circuit (1).