JP3035414B2 - Speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodynamic loudspeaker having a magnetic circuit in which a magnet is magnetically repelled.

[0002]

2. Description of the Related Art In recent years, the digital signal processing technology has been dramatically advanced, and the quality of electric signals supplied to a speaker has been greatly improved. Accordingly, a speaker capable of reproducing high-quality sound has been demanded. ing. On the other hand, with the integration of sound and video, it has become common for speakers to take measures against magnetic shielding in magnetic circuits in order to prevent the effects of color shift of the cathode ray tube and the like. Moreover, with the spread of rare-earth magnets having a high energy product, the magnetic circuit is required to be small and light while taking measures against magnetic field. Here, for high-quality sound reproduction, it is desirable that the driving force distortion of the speaker itself is extremely small. At present, as a countermeasure for reducing the driving force distortion of the speaker itself, a short voice coil system is used in which the winding width of the voice coil is made smaller than the thickness of the plate forming the center pole and the magnetic gap. on the other hand,
The anti-magnetic measures were implemented by joining two magnets magnetized in opposite directions to the upper and lower surfaces of a plate forming a magnetic gap with the center pole, respectively, and provided between the upper magnet and the outer peripheral portion of the under plate. This is accomplished by making the yoke magnetically the same as the underplate.

[0003] A conventional speaker will be described below.
FIG. 6 shows a sectional view of the structure of a conventional speaker. In FIG. 6, 1 is a center pole, 2 is an underplate in which the center pole 1 is joined to the center, and 3 is a center pole.
The plate 4 is arranged so as to form a magnetic gap with the side surface of the magnet 4, and the upper surface (that is, the plate 3 side) is magnetized to the N pole, and the lower surface (that is, the under plate 2 side) is magnetized to the S pole. The upper surface (that is, the yoke 6 side) is an S pole,
Another magnet whose lower surface (that is, the plate 3 side) is N-pole magnetized, 6 is a yoke constituting a magnetic circuit between the magnet 5 and the under plate 2, and 7 is a magnetic gap in accordance with an electric signal. , A voice coil bobbin 8 that supports the voice coil 7 and moves together with the voice coil 7, 9 is a damper, 10 is a diaphragm, 1
1 is an edge and 12 is a frame.

In a conventional speaker, a short voice coil system is used in which the thickness of the plate 3 is made larger than the winding width of the voice coil 7 in order to reduce driving force distortion. A magnet 5 magnetized in the direction is provided on the upper surface of the plate 3, and a yoke 6 in contact with the magnet 5 and the under plate 2 is provided. As a result, since the under plate 2 and the yoke 6 have the same magnetic polarity, the magnetic leakage to the outside of the speaker is reduced.

[0005]

In such a conventional technique, a center pole is required to reduce a driving force distortion which increases with a large amplitude in a low tone range at a large input and to keep the driving force constant. The plate 3 which forms a magnetic gap with the plate 1 needs to have such a thickness that the voice coil 7 exists within the magnetic gap within a desired amplitude range. However, in order to obtain a desired magnetic flux density in the magnetic gap, extremely large magnets 4 and 5 are required. Even if a rare earth magnet having a high energy product is used, the size of the magnets 4 and 5 becomes considerably large. As a result, the magnetic circuit becomes huge and the weight becomes very large, which poses a practical problem.

As a countermeasure against the magnetic field, the magnet 5 and the under plate 2 are joined by a yoke 6 so that the yoke 6 and the under plate 2 that widely cover the outer peripheral portion of the magnetic circuit are made to have the same polarity magnetically. Minimal magnetic leakage to the outside. However, with such a structure,
Magnetic leakage increases between the inner peripheral surface of the yoke 6 and the outer peripheral surfaces of the plate 3 and the magnets 4 and 5, so that the utilization efficiency of the magnets 4 and 5 is reduced. Further, if the distance between the inner peripheral surface of the yoke 6 and the outer peripheral surfaces of the plate 3 and the magnets 4 and 5 is increased in order to reduce the magnetic leakage, the volume and weight of the magnetic circuit increase, which is not practically preferable. Furthermore, in such a magnetic circuit in which the two magnets 4 and 5 are magnetically repelled,
The presence of the magnet 5 and the yoke 6 inevitably increases the distance between the voice coil 7 and the damper 9. If this distance is long, the voice coil bobbin 8 becomes long, which not only increases the weight of the voice coil bobbin 8, but also makes it easy for rolling to occur at the time of driving. There is a problem of generating sound.

An object of the present invention is to provide a small and lightweight speaker which has a high magnet utilization efficiency, can reduce the occurrence of rolling, and can reduce the occurrence of rolling in consideration of the conventional problems as described above.

[0008]

According to the present invention, there is provided a yoke which is disposed on an upper surface of one of the magnets, a center pole, two magnets disposed on upper and lower surfaces of the center pole in a direction of magnetic repulsion. The outer diameter is smaller than the inner diameter
And a yoke provided so that a magnetic gap is formed between a side plate of the center pole and an underplate disposed on the lower surface of the other magnet, and a side surface of the center pole. , The magnetic
Exists in gaps and generates driving force in response to electrical signals
A voice coil, and a voice coil from the voice coil.
A diaphragm mounted through a bobbin,
A damper for supporting an ilbobin,
The height is the boundary between the one magnet and the center pole.
Substantially the same height as the surface, or with the one magnet
Substantially the same height as the height of the interface with the top plate
Or a speaker that is between those two heights .

[0009]

According to the present invention, two magnets are arranged in a direction that magnetically repels each face of both end faces of the center pole,
The top plate is placed on the face of one magnet, the underplate is placed on the face of the other magnet, the yoke is placed on the outer periphery of the underplate, and a magnetic gap is formed between the yoke and the side of the center pole. , The efficiency of use of the magnet can be increased, and the occurrence of rolling can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing embodiments thereof.

FIG. 1 is a structural sectional view of a speaker according to a first embodiment of the present invention. That is, an under plate 17 is provided at the bottom in a cup-shaped frame 24 constituting the outer case of the speaker, and a columnar magnet 15 is provided at the center of the under plate 17. A cylindrical center pole 13 is provided on the upper surface, and a cylindrical magnet 1 is provided on the upper surface of the center pole 13.
4 are provided, and a top plate 16 is provided on the upper surface of the magnet 14. Also, under plate 17
Around the center pole 13
Is provided so as to form a magnetic gap with the side surface of the IGBT.

A voice coil 19 for generating a driving force in accordance with an electric signal is provided in the magnetic gap, and the voice coil 19 is attached to an end of a voice coil bobbin 20. It is configured to be able to move up and down. A damper 21 for supporting the voice coil bobbin 20 is provided between the middle part of the voice coil bobbin 20 and the frame 24.
A diaphragm 22 is attached to the upper end of the
Is attached to a frame 24 via an edge 23.

Next, the operation of the first embodiment will be described.

Tmu and Tmd in FIG.
4, 15 and the thickness Tc is the thickness of the center pole 13, T
p is the thickness of the top plate 16, Tu is the thickness of the under plate 17, Ty is the height of the yoke 18, Tv is the winding width of the voice coil 19, and Tvd is the distance from the center of the voice coil 19 to the damper 21. Voice coil 19
Is moving upward from the neutral point of the amplitude, the moving distance (the upward direction on the drawing with the neutral point as the origin,
The volume of the voice coil 19 existing in the magnetic gap is constant up to (Tc-Tv) / 2 when the downward direction is negative. Conversely, when the voice coil 19 moves downward, the moving distance is-.
Until (Tc-Tv) / 2, the driving force is constant because the volume of the voice coil 19 existing in the magnetic gap is constant.

Further, since the magnets 14 and 15 are magnetized in a direction of magnetic repulsion, the magnet 14 forms a magnetic path by the center pole 13, the yoke 18 and the top plate 16, and the magnet 15 is formed by the center pole. 13, a yoke 18, and an under plate 17 form a magnetic path. Therefore, the top plate 16, the under plate 17, and the yoke 18
Have the same magnetic polarity, and magnetic leakage outside the magnetic circuit is extremely reduced. Also, as described above, since there are two magnetic paths, all the magnetic flux supplied from the magnets 14 and 15 does not pass through the lower surface of the center pole 13 and the under plate 17 as in the prior art. The plate 17 is hardly magnetically saturated, and the diameter of the center pole 13 and the thickness Tu of the under plate 17 are reduced.
Can be reduced. When the magnetic circuit adopts the above structure, there is almost no space inside the magnetic circuit except for the magnetic gap.Therefore, the magnetic leakage excluding the magnetic gap inside is extremely small, and the magnet's magnetic utilization efficiency is high. Become. The small space inside the magnetic circuit and the high use efficiency of the magnet enable the magnetic circuit to be reduced in size and weight.

Here, in order to increase only the utilization efficiency of the magnet, the height Ty of the yoke 18 is Tc + Tmu + Tmd + T
Although it is desirable that the distance p is longer, when the distance Tvd between the voice coil 19 and the damper 21 is longer, rolling is likely to occur, and the yoke 18 or the center pole 13 and the voice coil 19 and the voice coil bobbin 20 are located within the magnetic gap. This causes problems such as the occurrence of abnormal sound due to collision and the disconnection of the voice coil 19. Therefore, in order to prevent this problem, the height Ty of the yoke 18 is set to Tc + Tmu + Tmd, and the voice coil 1
The distance Tvd between the damper 9 and the damper 21 is shortened.

FIG. 2 is a sectional view showing the structure of a speaker according to a second embodiment. The major difference from the first embodiment is that the height Ty of the yoke 18 is set to Tc + Tmd <Ty <Tc + Tm.
This is in the range of u + Tmd, and the other configurations are the same.

The operation of this embodiment is exactly the same as that of the first embodiment except that the height Ty of the yoke 18 is
And the magnet 14 is lower than the boundary surface, the utilization efficiency of the magnet 14 is slightly reduced, the magnetic flux density in the magnetic gap is also slightly reduced, and only the magnetic leakage is slightly increased. However, the voice coil 19 and the damper 2
Since the distance Tvd of 0 becomes shorter, the possibility of causing rolling is further reduced.

Next, FIG. 3 shows a sectional view of the structure of the speaker according to the third embodiment. A major difference from the first and second embodiments is that the height Ty of the yoke 18 is equal to Tc + Tmd. Other configurations are the same.

The operation of this embodiment is exactly the same as that of the first and second embodiments, except that the height Ty of the yoke 18 becomes equal to the boundary between the center pole 13 and the magnet 14,
The utilization efficiency of the magnet 14 is slightly lower than that of the second embodiment, and the magnetic flux density in the magnetic gap is slightly lower.
Only the magnetic leakage will increase slightly. However, since the distance Tvd between the voice coil 19 and the damper 21 is further reduced, the possibility of causing rolling is extremely small.

Next, FIG. 4 shows a sectional view of the structure of the speaker according to the fourth embodiment. Also, the magnet 1 on the center pole
FIG. 5 shows a perspective view of the joint between the top plate 4 and the top plate 16. The major difference from the previous embodiment is that the magnet 14
In order to improve the utilization efficiency of the magnet 14, a plurality of recesses are provided on the top plate 16 side of the magnet 14 at equal intervals in a region including the outer peripheral portion, and the top plate 16 is fitted to the recess of the magnet 14. Is a structure in which a convex portion is provided. By adopting such a structure, since the outer peripheral surface of the convex portion of the top plate 16 and the yoke 18 are adjacent to each other,
The magnetic resistance in the magnetic path formed by the magnet 14, the center pole 13, the yoke 18, and the top plate 16 is reduced. As a result, the utilization efficiency of the magnet 14 is increased, and magnetic leakage to the outside of the magnetic circuit is reduced.

In the fourth embodiment, the yoke 18
The height of the magnet 14 and the top plate 16 is the same as that of the first or second embodiment.
May be configured to have an uneven shape.

Further, in the fourth embodiment, the irregularities on the joint surface between the magnet 14 and the top plate 16 are made equal, but the present invention is not limited to this.

[0024]

As is apparent from the above description, the present invention has the advantages of high magnet utilization efficiency, reduced occurrence of rolling, small size and light weight.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of a speaker according to a first embodiment of the present invention.

FIG. 2 is a structural sectional view of a speaker according to a second embodiment of the present invention.

FIG. 3 is a structural sectional view of a speaker according to a third embodiment of the present invention.

FIG. 4 is a structural sectional view of a speaker according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing a fitting portion between a top plate and a magnet of the speaker of the fourth embodiment.

FIG. 6 is a structural sectional view of a conventional speaker.

[Explanation of symbols]

 13 center pole 14 magnet 15 magnet 16 top plate 17 underplate 18 yoke 19 voice coil 20 voice coil bobbin 21 damper 22 diaphragm 23 edge 24 frame

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho-59-48197 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04R 9/02 102

Claims (3)

(57) [Claims] 1. A center pole, two magnets arranged in directions repelling magnetically on upper and lower surfaces of the center pole, and an inner periphery of a yoke arranged on an upper surface of one of the magnets.
A magnetic gap is formed between a top plate having an outer diameter smaller than a diameter , an under plate arranged on the lower surface of the other magnet, and an outer periphery of the under plate, and a side surface of the center pole. And the yoke provided in the magnetic gap,
A voice coil for generating a driving force according to a signal;
Attached through the voice coil bobbin from the chair coil
And a damper for supporting the voice coil bobbin.
And the height of the yoke is equal to that of the one magnet.
Height substantially equal to the height of the boundary surface with the center pole
Or between the one magnet and the top plate
Substantially the same height as the interface, or two heights
Speaker, characterized in that in between the. 2. A are joined and one of the magnets the top plate, an outer peripheral portion of the joint surface, the speaker according to claim 1, characterized in that it is formed in the uneven shape. 3. The loudspeaker according to claim 2 , wherein the irregular shapes are equally spaced.