JPH0534797U - Magnetic circuit for speaker - Google Patents

Abstract

(57) [Summary] [Purpose] A secondary magnet is used to reduce the leakage flux and improve the magnetic flux density in the magnetic gap. [Structure] An inner magnet type magnetic circuit is fitted with and held by a sub-circular sub-magnet having a thickness substantially equal to that of the upper plate on the inner side surface of a center hole formed at the upper end of the upper plate, and the above-mentioned difference A structure in which the inner surface of the center hole of the direction magnet is formed as the outer surface of the magnetic gap, the sub magnets are inserted and mounted in series in the magnetic path direction of the main magnet, and the magnets are magnetized in the radial direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic circuit for a speaker, in which the performance of a main magnet used for an inner magnet type is brought out to a high degree and a magnetic flux leaking to the surroundings is reduced by a sub magnet.

[0002]

[Prior Art]

 As shown in FIGS. 7 and 8, the magnetic circuit (5 ″) of the speaker (11 ′) of this type conventionally has a cylindrical shape, for example, an alnico, in a recess provided in the inner bottom surface of the lower plate (2e ′). Place the magnet (3 '), fix the center pole (1') on it, and insert the center pole (1 ') into the center magnetic hole (2d') of the upper plate (2c '). Of the lower side plate (2e ') of the lower plate (2e') and the lower side part (2b ') of the side part (2a') of the cylindrical yoke (2 '). The so-called inner magnet type magnetic circuit structure in which the annular magnetic air gap (6 ′) was formed by fitting and coupling to the inner surface of the portion (2f ′) was mainly used.

Then, the voice coil (8 ') is supported by the damper (9') in the magnetic gap (6 ') of the magnetic circuit (5 "), and the outer periphery of the tip is attached to the frame (7'). It was assembled as a speaker (11 ') by attaching the tip of the diaphragm (10').

[0004]

[Problems to be solved by the device]

 Therefore, in the conventional inner magnet type magnetic circuit (5 ") of this kind, as shown in FIG. 8, the magnetic gap (6 ') is the entire magnetic path of the magnetic circuit (5"). Of these, the magnetic reluctance is the largest, and as a result, the flow of lines of magnetic force mostly leaks out of the magnetic air gap (6 ') and leaks out. Since the ratio of magnetic flux passing through is small (Fig. 8), there is a problem that a speaker with good efficiency cannot be obtained.

Therefore, the present invention uses a conventional alnico magnet, for example, as the main magnet (3) in order to solve the problems of the conventional inner magnet type magnetic circuit (5 "). However, by using a similar alnico magnet as a sub-magnet (4) in a part of the magnetic path, the main magnet exerts the performance of the magnetic circuit (5) and the magnetomotive force of the sub-magnet (4) is utilized. , The magnetic flux that leaks to the outside of the magnetic air gap (6) is reduced, the use efficiency of the primary and secondary magnets (3), (4) is improved, and the space factor of the magnet is improved. It is intended to dramatically improve the magnetic flux density of the air gap (6) to provide a magnetic circuit (5) suitable for a compact, powerful, and highly efficient speaker.

[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 embodiments. The present invention, in an inner magnet type magnetic circuit, shows the upper end portion (2d) of the upper plate (2c). ), The inner surface (2h) of the center hole (2e) formed in (1) is fitted with and retained by a magnet (4) in the shape of a circular ring with an approximately equal thickness to the upper plate (2c). The inner surface of the central hole of (4) is formed as the outer surface (6e) of the magnetic gap (6), and the magnet (4) is inserted and mounted in series in the magnetic path direction of the main magnet (3). This is a magnetic circuit for speakers (5) in which (4) is magnetized in the radial direction.

[0007]

[Action]

 Since the present invention has such a structure, it is necessary to insert the auxiliary magnet (4) in series with a part of the magnetic path of the main magnetic circuit using the conventional alnico magnet shown in FIG. 7, for example. As shown in Figs. 1 and 2, the magnetomotive force of the sub-magnet (4) is used to reduce the leakage magnetism leaking to the outside of the magnetic air gap (6), and the magnetic flux is generated in the magnetic air gap (6). You can concentrate.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are views showing an embodiment of the first invention, FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is a longitudinal sectional view showing a flow of magnetic force lines of the embodiment of FIG. It is a figure.

The first aspect of the present invention is that, in an inner magnet type magnetic circuit, an upper plate (2c) is formed on an inner side surface (2h) of a central hole (2e) formed at an upper end (2d) of the upper plate (2c). A sub-circular sub magnet (4) of approximately the same thickness is fitted and held, and the inner surface of the center hole of the sub magnet (4) is formed as the outer surface (6e) of the magnetic space (6). The secondary magnet (4) is inserted and mounted in series in the magnetic path direction of the main magnet (3), and the magnet (4) is magnetized in the radial direction to provide a speaker magnetic circuit (5).

A second aspect of the present invention is a modified structure of the first aspect of the present invention. As shown in FIG. 3, the upper surface of the upper plate (2c) in which the sub magnet (4) is fitted and held is A magnetic circuit (5 ') for a speaker equivalent to the first invention, which is located at least (D) higher than the upper surface (1a) of the center pole (1) including the upper surface of the magnet (4). Here, the relational expression of D> 0 holds.

Although the embodiments considered to be typical of the present invention have been described above, the present invention is not necessarily limited only to the structures of these embodiments, and has the above-mentioned configuration requirements according to 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.

[0012]

[Effect of the device]

 As is apparent from the above description, since the present invention has such a structure, a conventional alnico magnet, for example, is used as the main magnet, and a part of the magnetic path is used as the sub magnet (4). By using the magnetic field performance of the main magnet and the magnetomotive force of the anisotropic magnet (4), the leakage magnetism that leaks to the outside of the magnetic air gap (6) can be reduced, and The magnetic flux density of the magnetic air gap is dramatically improved by increasing the use efficiency of both magnets (3) and (4) to improve the space factor of the magnet, resulting in a small size, high strength, and high strength. The magnetic circuit (5) is suitable for an efficient speaker. The comparison of the leakage flux of the magnetic circuit between the conventional example and the present invention is calculated from the comparison of the reluctance of the magnetic gap.

[0013]

[Table 1]

A comparison of the real numbers of the leakage magnetic flux measured along the direction parallel to the axis of the magnetic circuit in the vicinity of the side surface of the magnetic circuit between the conventional example and the present invention is as shown in FIGS. The horizontal axis shows the distance from the magnetic circuit (origin 0), and the vertical axis shows the absolute value of the magnetic flux density from that point. The measurement position is as shown in FIG. As can be seen from the above, the proposed embodiment has 15 to 23% less magnetic flux leakage than the conventional example, and the effect is exhibited by effectively acting. That is, there is a large difference in the leakage magnetic flux between the conventional example shown in FIG. From this, the difference is the largest at the measurement point 2 cm from the origin O point outside the magnetic circuit.

FIG. 6 is a comparison of the magnetic flux densities generated in the magnetic gap of the conventional example and the embodiment of the present invention. The horizontal axis represents the distance from the upper end (0) of the magnetic gap, and the vertical axis represents the magnetic flux density. Represents the absolute value of. As can be seen, in the vicinity of the center of the magnetic gap, the present invention has 10,200 gauss and the conventional example has 8,000 gauss, which is about 24% higher than that of the conventional example. The second invention is a modification of the speaker magnetic circuit according to claim 1, as shown in FIG. 3, in which the upper surface of the upper plate (2c) in which the sub magnet (4) is fitted and held is , The top of the center pole (1) including the top surface of the magnet (4) is positioned at least higher than the top surface (1a) of the center pole (1). Since the magnetic field faces the middle part of the magnetic air gap (6) of the sub-magnet (4), the magnetic flux is drawn downward, the leakage rate is reduced, and the effect of increasing the magnetic flux density of the magnetic air gap is further reduced. improves .

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing the flow of magnetic force lines according to the embodiment of the present invention in FIG.

FIG. 3 is a vertical sectional view of another embodiment of the present invention.

FIG. 4 is a comparison diagram of side leakage magnetic flux of a magnetic circuit.

FIG. 5 is a diagram showing the positions of measurement points in FIG.

FIG. 6 is a comparison diagram of magnetic flux densities in a magnetic gap.

FIG. 7 is a vertical sectional view of a conventional example.

FIG. 8 is a vertical cross-sectional view showing the flow of magnetic force lines in a conventional example.

[Explanation of symbols]

 (1) Center pole (1a) Center pole tip (2) Cylindrical yoke (2a) Cylindrical yoke side surface (2b) Cylindrical yoke lower inner surface (2c) Upper plate (2d) Upper end (2e) Center hole (2h) Inner surface (3) Main magnet (4) Secondary magnet (5) Magnetic circuit (5 ') Magnetic circuit (6) Magnetic air gap (6e) Magnetic air gap outer surface (D) Difference

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[Procedure amendment]

[Submission date] December 6, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (2)

[Scope of utility model registration request] 1. In an inner magnet type magnetic circuit, an upper plate
Inner surface (2h) of the center hole (2e) formed in the upper end (2d) of (2c)
A sub-magnet (4) in the shape of a circular ring of approximately the same thickness as the upper plate (2c) is inserted and held, and the inner surface of the center hole of the sub-magnet (4) is fixed to the magnetic gap (6). It is formed as an outer surface (6e), and the auxiliary magnet (4) is inserted and installed in series in the magnetic path direction of the main magnet (3).
A magnetic circuit for a speaker, wherein the magnet (4) is magnetized in the radial direction. 2. The auxiliary magnet (4) is inserted and held,
The upper surface of the upper plate (2c), including the upper surface of the sub magnet (4),
2. The speaker magnetic circuit according to claim 1, wherein the center pole (1) is positioned at least (D) higher than the upper surface (1a) of the center pole (1).