JPH06311596A - Magnetic circuit for speaker - Google Patents

Abstract

PURPOSE:To suppress the influence of an external magnetic field by substituting a part of magnetic circuit for a magnetic material magnetically saturated by the intensity of magnetic field smaller than the intensity Hs of the magnetic field in correspondence with magnetic flux density Bs for which a magnetic material composing a magnetic circuit is magnetically saturated for a part. CONSTITUTION:The magnetic circuit is formed with both a magnet 11, and magnetic members 12, 13, and 14 which form a magnetic gap by magnetically coupling with the magnet. Sub magnetic members 12a, 13a, and 14a are provided with a magnetic saturation point within a range of smaller magnetic intensity than the intensity Hp of the magnetic field of a change point changing from a linear area to a nonlinear area in the magnetic saturation curve of the members 12-14. Also, they are provided with saturation magnetic flux density smaller than the saturation magnetic flux density Bs of the members 12-14 and larger than the magnetic flux density Bg of a gap 15. The members 12a, 13a, and 14a are substituted for a part of the members 12, 13, and 14. Thereby, it is possible to suppress the fluctuation of the magnetic flux density generating in the magnetic material in the magnetic circuit even when the external magnetic field is added and to suppress the influence of the external magnetic field, and as the result, the fluctuation of the flux density generating in the gap can be suppressed.

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 a part of a member constituting a magnetic circuit is replaced with a member having different physical properties.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, the structure of a magnetic circuit for a speaker of this type has a center pole (12) made of soft iron, a top plate (13) and a bottom plate centered around a magnet (11).
A magnetic member made of (14) is joined to form an annular magnetic gap (15). And as prior art,
As disclosed in Japanese Unexamined Patent Publication No. 1-300696, there is a ring-shaped magnet in which a ring-shaped magnet having magnetic poles different from each other is attached to the inner circumference or the outer circumference. Such a magnetic circuit minimizes the leakage magnetic flux around the magnetic circuit and increases the magnetic flux density in the air gap,
The present invention is aimed at downsizing and high performance, and is similar in object, constitution, and effect to the present invention.

[0003]

Therefore, in the above-described conventional magnetic circuit for a speaker of this type, depending on the influence of the magnetic field from the outside in the vicinity or the constituent parts,
There is a problem that the magnetic flux density of the magnetic gap may fluctuate.

The magnetic field originally generated in the magnetic gap may fluctuate due to the influence of the magnetic field from the outside of the magnetic circuit or the influence of the magnetic field generated from the constituent members of the magnetic circuit. The magnetic field of these fluctuation factors (the magnetic field other than the magnetic field of the magnetic gap) is hereinafter referred to as "external magnetic field" regardless of whether the generation source is inside the magnetic circuit or outside.

In order to improve the performance of the magnetic circuit, it is necessary to 1) remove the external magnetic field or 2) reduce the influence of the external magnetic field. The present invention intends to improve the performance of the magnetic circuit by the above 2).

When the magnetic flux density generated in the magnetic air gap (15) when there is no external magnetic field is Bg and the magnetic flux density when influenced by the external magnetic field is Bg ', the fluctuation amount of the magnetic flux density ΔBg
Is ΔBg = | Bg−Bg ′ | (in the case of a linear magnetic field, ΔBg
= | Bout |), which is a cause of adverse effects on devices that use magnetic circuits. However, to judge the effect, △ Bg
R% = (ΔBg / Bg when there is no “external magnetic field”) × 1
A magnetic flux density variation rate (R) represented by 00% is used.

As described above, in the conventional speaker magnetic circuit, the air gap magnetic flux density fluctuates due to the external magnetic field, which is not preferable in the design of the speaker device, but also causes the deterioration of the sound quality after the speaker device is completed. There was a problem.

In order to solve the problem that the conventional magnetic circuit for a speaker has, the present invention replaces a part of the constituent members of the magnetic circuit with a sub-magnetic member having different magnetic characteristics. In order to suppress the fluctuation of the air gap magnetic flux density, it is possible to guarantee the designed air gap magnetic flux density value and provide a magnetic circuit for a speaker suitable for an electroacoustic transducer of a high sound quality speaker device.

[0009]

The structure of the present invention for achieving the above object will be described with reference to FIGS. 1 to 8 corresponding to the embodiments. The present invention provides a magnet (11) and the magnet. In a magnetic circuit having a magnetic member (12), (13), (14) magnetically coupled with (11) to form a magnetic gap (15), the magnetic member (12), (13), ( In the magnetic saturation curve (B-H curve) of 14), the magnetic saturation point is set within the range of the magnetic field strength smaller than the magnetic field strength (Hp) of the change point (P) that changes from the linear region to the non-linear region. And having the magnetic body (12), (13),
In the sub-magnetic member (12a), (13a), (14a) having a saturation magnetic flux density smaller than the saturation magnetic flux density (Bs) of (14) and larger than the magnetic flux density (Bg) of the magnetic gap (15), A magnetic circuit for a speaker, wherein a part of the magnetic members (12), (13), (14) is replaced.

[0010]

In the present invention, the magnetic material that is magnetically saturated with a small magnetic field strength is replaced with a part of the constituent members of the magnetic circuit. Therefore, even if an external magnetic field is applied, the magnetic material in the magnetic circuit is The fluctuation of the magnetic flux density generated in the body can be suppressed, the influence of the “external magnetic field” can be suppressed, and as a result, the fluctuation of the magnetic flux density generated in the magnetic gap can also be suppressed. As a result, the speaker design can be facilitated and the performance of the finished speaker product can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing one embodiment of the present invention. FIG. 1 shows a conventional example, magnetic materials of Examples 1 and 2 used in numerical experiments of the present invention. Magnetic saturation (B
-H) curve is shown. FIG. 2 is a sectional view of the magnetic circuit of the first embodiment. FIG. 3 is a sectional view of the magnetic circuit of the second embodiment.

Example 1 In FIG. 1, a curve A shows a magnetization curve (B-H curve) of a magnetic material forming a magnetic circuit, and the magnetic field strength is saturated at a point (Hs) of 1,000 Oe. , The magnetic flux density at that time is 19,600 Ga
Takes the value of uss (Bs). Further, in the B-H curve, the magnetic field strength changes from the linear region to the non-linear region at the point (Hp) of 50 Oe, and the magnetic flux strength at that time is 16,000.
It is 0 Gauss (Bp).

Further, the magnetic flux density (Bg) of the magnetic gap (15) of the magnetic circuit (shown in FIG. 9) using the magnetic material is 1
It is 0,890 Gauss.

In FIG. 1, a curve B shows a BH curve of the sub-magnetic member (14a) used in Example 1, which is in a saturated state when the magnetic field strength is 30 Oe, and the magnetic flux density at that time is It is 14,000 Gauss. As shown in FIG. 2, the first embodiment has a configuration in which the annular portion of the lower plate (14) of the magnetic circuit, which is close to the center pole (12), is replaced with the sub-magnetic member (14a) having the above magnetic characteristics. Is.

Example 2 In FIG. 1, a curve C shows a BH curve of the sub-magnetic members (12a) and (13a) used in Example 2, which is in a saturated state at a magnetic field strength of 20 Oe. And the magnetic flux density at that time is 12,000 Gauss. As shown in FIG. 3, the second embodiment has the above-mentioned magnetic characteristics in the annular portions of the portions of the top plate (13) of the center pole (12) of the magnetic circuit facing the magnetic gaps (15). This is a configuration in which the sub magnetic material members (12a) and (13a) are replaced.

As shown in FIG. 4, the magnetic air gap was divided into 15 elements, and the magnetic flux densities of the first to fifth elements in the central portion were numerically tested for the conventional example and the first and second examples. Further, as shown in FIG. 5 as an external magnetic field, a coil (H ₀ ) is wound around the center pole and 100
A current of AT is flowed, and depending on the direction, a magnetic field in the direction of increasing the magnetic flux density of the magnetic gap shown in FIG. 6 (plus direction) and a magnetic field in the direction of decreasing magnetic flux density shown in FIG. 7 (minus direction) are generated. The magnetic flux densities of the elements Nos. 1 to 5 in the examples and the respective examples are measured, and the magnetic flux density fluctuation rate R
The result of calculating is shown in FIG. As is clear from FIG. 8, in the conventional example, both the positive side fluctuation and the negative side fluctuation have about 5%, but in the first embodiment, this is 4%.
%, In Example 2, this could be reduced to about 1.5% to 3%.

Although the examples considered to be representative of the present invention have been described above, the present invention is not necessarily limited to the structures of these examples, and has the above-mentioned constitutional requirements referred to in the present invention, and The present invention can be carried out by appropriately modifying it within a range that achieves the object of the present invention and has the following effects.

[0018]

As is apparent from the above description, since the present invention replaces a part of the magnetic member forming the magnetic circuit with the sub magnetic member having different magnetic characteristics, the magnetic member is It has a remarkable effect that the magnetic flux density of the magnetic gap is not largely reduced as in the case of replacing with a conductor. For example, in the magnetic circuit having a structure in which the outer circumference of the pole is replaced with a conductor having a thickness of 0.275 mm, the reduction of the gearup density reaches 12%, whereas in the configuration of the present invention, the reduction is 1.5-5%. It stayed.

The magnetic circuit of the present invention can also be adopted as a magnetic circuit for an electric motor. Further, according to the present invention, since the fluctuation of the magnetic flux density of the magnetic gap can be suppressed regardless of the location of the external magnetic field, not only the design of the magnetic circuit can be facilitated, but also the characteristics of the finished speaker can be maintained. Becomes

According to the present invention, in the above-described conventional magnetic circuit for a speaker, the magnetic flux density of the magnetic air gap may vary depending on the influence of the external magnetic field in the vicinity or constituent parts. The problem has been completely solved, and as is apparent from the above description, the present invention is one in which a part of the constituent members of the magnetic circuit is replaced with a magnetic member having different magnetic characteristics. Therefore, the fluctuation of the magnetic flux density can be reduced, and the remarkable effect of achieving high performance of the magnetic circuit can be expected.

Further, the present invention also has an effect that the magnetic flux density of the magnetic gap does not largely decrease as in the case where the magnetic body is changed to a conductor, which is not expected in the conventional art. Was reached.

It goes without saying that the speaker magnetic circuit of the present invention can be directly applied as a magnetic circuit for an electric motor.

[Brief description of drawings]

FIG. 1 is a conventional example, Example 1 used in a numerical experiment of the present invention,
BH curve of 2.

FIG. 2 is a sectional view of the magnetic circuit according to the first embodiment.

FIG. 3 is a sectional view of a magnetic circuit according to a second embodiment.

FIG. 4 is a diagram of element division of a magnetic gap used in the numerical experiments of FIGS. 6 and 7.

FIG. 5 is a diagram showing the relationship between the magnetic gap used in the numerical experiments of FIGS. 6 and 7 and a coil for applying an external magnetic field.

FIG. 6 is a diagram showing the amount of fluctuation of the magnetic flux density when there is no external magnetic field, with respect to the magnetic flux density of the magnetic gap.

FIG. 7 is a diagram showing the amount of fluctuation of the magnetic flux density in the presence of an external magnetic field, with respect to the magnetic flux density of the magnetic gap.

FIG. 8 is a diagram showing a magnetic flux density variation rate of a conventional example and an example.

FIG. 9 is a sectional view of a conventional magnetic circuit.

[Explanation of symbols]

 (11) Magnet (12) Center pole (12a) Center pole facing magnetic air gap (13) Upper plate (13a) Upper plate facing magnetic air gap (14) Lower plate (15) Magnetic air gap (Bg ) Magnetic flux density in magnetic gap (Bs) Saturated magnetic flux density (Bx) Saturation magnetic flux density (Hp) Magnetic field (Hs) Magnetic field strength (S) Saturation point (H) Magnetic field strength

Claims (1)

[Claims] 1. A magnet (11) and the magnet (11)
A magnetic material member (1) that is magnetically coupled to form a magnetic air gap (15).
2), (13), and (14), in the magnetic saturation curve (BH curve) of the magnetic member (12), (13), (14), from the linear region to the non-linear region. Has a magnetic saturation point within the range of the magnetic field strength smaller than the magnetic field strength (Hp) of the change point (P) that changes to (1) and the saturation of the magnetic bodies (12), (13), (14). A sub-magnetic member having a saturation magnetic flux density smaller than the magnetic flux density (Bs) and larger than the magnetic flux density (Bg) of the magnetic gap (15).
(12a), (13a), (14a), the magnetic member (12), (13), (14)
A magnetic circuit for a speaker, characterized in that a part of the above is replaced.