JP2568241Y2 - Magnetic circuit for speaker - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit for a loudspeaker in which the performance of a main magnet used for an inner magnet type is brought out to a high degree and a leakage magnetic flux to the surroundings is reduced by a sub magnet.

[0002]

2. Description of the Related Art Conventionally, a magnetic circuit of a speaker (11 ') of this kind.
(5 ") is the lower plate (2e ') as shown in FIGS.
In the concave part provided in the inner bottom surface of the column, for example, a cylindrical Alnico magnet
Place (3 '), fix the center pole (1') on it,
In the center magnetic gap hole (2d ') of the upper plate (2c'), the tip magnetic pole portion (1a ') of the center pole (1') is viewed, and the side surface (2a) of the cylindrical yoke (2 ') is seen. '), The lower side surface portion (2b') of the lower plate (2e ') is fitted and fixed to the inner surface portion of the side edge portion (2f') of the lower plate (2e '), thereby forming an annular magnetic air gap (6'). The so-called inner magnet type magnetic circuit structure formed was mainly used.

The magnetic gap (6 ') of the magnetic circuit (5 ")
The voice coil (8 ') is supported by a damper (9') inside, and the tip of the diaphragm (10 ') attached to the frame (7') is attached to the outer periphery of the tip, and the speaker (11 ') Was assembled as

[0004]

Therefore, in this type of conventional internal magnetic type magnetic circuit (5 "), as shown in FIG. 8, the magnetic gap (6 ') is formed by the magnetic circuit (5'). The magnetic resistance is the largest in the entire path of the magnetic path in "). Therefore, the flow of the lines of magnetic force mostly leaks out of the magnetic air gap (6 ') and leaks out. Magnetic air gap
Since the ratio of the magnetic flux passing through (6 ') is small (FIG. 8), there is a problem that an efficient speaker cannot be obtained.

Accordingly, the present invention has been made to solve the problem of the conventional inner magnet type magnetic circuit (5 ").
By using a conventional alnico magnet as the main magnet (3) and using a similar alnico magnet as a sub magnet (4) in a part of the magnetic path, the performance of the magnetic circuit (5) by the main magnet can be exhibited. Utilizing the magnetomotive force of the secondary magnet (4) to reduce the leakage magnetism leaking outside the magnetic air gap (6), the primary and secondary magnets (3),
With the aim of improving the use efficiency of (4) and improving the space factor of the magnet, the magnetic flux density of the magnetic air gap (6) is dramatically improved, making it a compact, powerful and highly efficient speaker. It is intended to provide a suitable magnetic circuit (5).

[0006]

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. A right annular magnet (4), approximately the same thickness as the upper plate (2c), is fitted into the inner surface (2h) of the center hole (2e) drilled in the upper end (2d) of the plate (2c). The inner surface of the center hole of the auxiliary magnet (4) is formed as the outer surface (6e) of the magnetic gap (6), and the magnet (4) is connected in series in the magnetic path direction of the main magnet (3). A speaker magnetic circuit (5) inserted and mounted and magnetized in the radial direction with the magnet (4).

[0007]

According to the present invention, the auxiliary magnet (4) is inserted in series with a part of the magnetic path of the conventional main magnetic circuit using an alnico magnet as shown in FIG. As shown in FIGS. 1 and 2, by using the magnetomotive force of the sub-magnet (4) to reduce the leakage magnetism leaking to the outside of the magnetic gap (6), The magnetic flux can be concentrated.

[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 first invention, FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is a longitudinal sectional view showing a flow of magnetic field lines in the embodiment of FIG. FIG.

The first device of the present invention relates to an inner magnet type magnetic circuit,
At the inner surface (2h) of the center hole (2e) drilled at the upper end (2d) of the upper plate (2c), a right circular sub-magnet (4) approximately equal in thickness to the upper plate (2c) is provided. The auxiliary magnet (4)
The inner surface of the center hole is formed as the outer surface (6e) of the magnetic air gap (6), and the sub magnet (4) is inserted and mounted in series in the magnetic path direction of the main magnet (3). ) Is a speaker magnetic circuit (5) magnetized in the radial direction.

The second invention is a modified structure of the first invention. As shown in FIG. 3, the upper surface of the upper plate (2c) in which the above-mentioned sub-magnet (4) is fitted and held, A magnetic circuit (5 ') for a speaker according 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 which are considered to be representative of the present invention have been described above, the present invention is not necessarily limited only to 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.

[0012]

[Effects of the Invention] As is apparent from the above description, the present invention has such a structure. Therefore, a conventional magnet such as an alnico magnet is used as the main magnet, and the auxiliary magnet (4) is used.
As a part of the magnetic path, the performance of the magnetic circuit by the main magnet and the use of the magnetomotive force of the anisotropic magnet (4) to reduce leakage magnetism leaking outside the magnetic air gap (6) The purpose is to increase the efficiency of use of the main and sub magnets (3) and (4) and to improve the space factor of the magnets. , Powerful,
And a magnetic circuit (5) suitable for a highly efficient speaker. The following Table 1 shows a comparison of the leakage flux of the magnetic circuit between the conventional example and the present invention based on the comparison of the reluctance of the magnetic air gap.

[0013]

[Table 1]

A comparison of the real numbers of the leakage magnetic flux measured in the direction parallel to the axis of the magnetic circuit between the conventional example and the side of the magnetic circuit of the present invention is as shown in FIGS. The axis indicates the distance from the magnetic circuit (origin 0), and the axis of ordinate indicates the absolute value of the magnetic flux density from that point. The measurement positions are as shown in FIG. As can be seen from the above, the embodiment of the present invention has a smaller leakage magnetic flux by 15 to 23% than the conventional example, and works effectively to show the effect. That is, the difference between the leakage magnetic flux is large in the conventional example shown in FIG. From this, the difference is 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 density generated in the magnetic air gap between the conventional example and the embodiment of the present invention. The horizontal axis indicates the distance from the upper end (0) of the magnetic air gap, and the vertical axis indicates the magnetic flux density. Represents the absolute value of As can be seen, near the center of the magnetic air gap, the present invention is 10,200 gauss, the conventional example is 8,000 gauss,
The embodiment is improved by about 24% compared to the conventional example. The second invention is a modification of the magnetic circuit for a loudspeaker according to claim 1, as shown in FIG. 3, wherein the upper surface of the upper plate (2c) in which the auxiliary magnet (4) is fitted and held is formed. Due to the structure positioned at least higher than the upper surface (1a) of the center pole (1), including the upper surface of the magnet (4), the magnetic flux concentrates at the corners of the upper surface (1a) of the center pole (1). Where the secondary magnet
Since it faces the middle part of the magnetic gap (6) of (4), the magnetic flux is drawn downward, the leakage rate decreases, and the effect of increasing the magnetic flux density of the magnetic gap further improves.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view showing the flow of the magnetic field lines in the embodiment of the present invention in FIG. 1;

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

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

FIG. 5 is a diagram showing positions of measurement points in FIG. 4;

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

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

FIG. 8 is a longitudinal sectional view showing a flow of lines of magnetic force of a conventional example.

[Explanation of symbols]

 (1) Center pole (1a) Center pole tip (2) Cylindrical yoke (2a) Cylindrical yoke side (2b) Cylindrical yoke lower inner side (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

Continuation of the front page (56) References JP-A-60-167309 (JP, A) JP-A-51-54424 (JP, A) JP-A-1-300696 (JP, A) Jpn. , U) Fully open sho 59-96994 (JP, U) Really open sho 59-104697 (JP, U) Really open sho 55-31386 (JP, U) Really open sho 59-57095 (JP, U) Real open sho 57-41607 (JP, U) JP-B-45-12105 (JP, B1)

Claims (2)

(57) [Scope of request for utility model registration] In the internal magnetic type magnetic circuit, the thickness of the upper plate (2c) is substantially the same as that of the upper plate (2c) on the inner surface (2h) of the center hole (2e) formed in the upper end (2d) of the upper plate (2c). The sub-magnet (4) having the same straight annular shape 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 gap (6). 3) the sub magnet (4) in series in the direction of the magnetic path by inserting mounting of the auxiliary magnet (4)
Is a magnetic circuit for a speaker that is magnetized radially. 2. A were held by fitting the said auxiliary magnet (4), the upper surface of the upper plate (2c), including the upper surface of the auxiliary magnet (4), the upper surface of the center pole (1) (1a) Also
The magnetic circuit for a speaker according to claim 1, wherein the magnetic circuit is arranged at a high position .