JPH06125596A - Speaker - Google Patents

Abstract

PURPOSE:To improve the utilizing efficiency of a magnet and to reduce the generation of rolling by arranging two magnets on both end faces in the direction magnetically repelling each other. CONSTITUTION:When a voice coil 19 moves upward from the neutral point of the amplitude, the volume of the voice coil 19 in the magnetic gap is kept constant as long as the travelling distance is within (Tc-Tv)/2. Thus, the driving power is made constant Further, magnets 14 and 15 are polarized in the direction so that they repell each other and the magnet 14 forms a magnetic path by a center poll 13, yoke 18, and top plate 16. The magnet 15 forms the magnetic path by the pole 13, yoke 18, and underplate 17. Thus, the plates 16 and 17 become magnetically like-pole and the flux leakage to the outside of the magnetic circuit is remarkably reduced.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, since digital signal processing technology has advanced dramatically, the quality of electric signals supplied to a speaker has been significantly improved, and a speaker capable of reproducing high-quality sound has been demanded correspondingly. ing. On the other hand, along with the fusion of sound and video, it has become common for speakers to prevent the magnetic circuit from being magnetically shielded in order to prevent the influence of color shift of the cathode ray tube. Moreover, along with the widespread use of rare earth magnets having a high energy product, it is required that the magnetic circuit be compact and lightweight while being magnetically shielded. Here, in order to reproduce high-quality sound, it is desirable that the driving force distortion of the speaker itself is extremely small. At present, as a measure for reducing the driving force distortion of the speaker itself, a short voice coil method is used in which the winding width of the voice coil is smaller than the thickness of the plate forming the magnetic gap with the center pole. on the other hand,
As a measure for preventing the magnetic field, two magnets, which are magnetized in opposite directions, are joined to the upper surface and the lower surface of the plate that forms a magnetic gap with the center pole, and are provided between the magnet above and the outer peripheral portion of the under plate. This is done by making the yoke magnetically the same as the underplate.

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

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

[0005]

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

In addition, as a measure against magnetic shielding, 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 magnetically homopolar. Minimal magnetic leakage to the outside. However, conversely in 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, and the utilization efficiency of the magnets 4 and 5 is low. If the space 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 preferable in practice. Furthermore, in a magnetic circuit in which such two magnets 4 and 5 are magnetically repulsed,
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 becomes long, not only the weight of the voice coil bobbin 8 becomes large because the voice coil bobbin 8 becomes long, but also the rolling easily occurs at the time of driving, and the magnetic gap comes into contact with the voice coil 7 or the voice coil bobbin 8 to cause an abnormality. There is a problem of generating sound.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a speaker which has high utilization efficiency of a magnet, can reduce rolling, and is small and lightweight.

[0008]

According to the present invention, there is provided a center pole, two magnets arranged on both end surfaces of the center pole in a magnetically repulsive direction, and one magnet surface. A top plate, an under plate arranged on the surface of the other magnet, and a yoke arranged on the outer peripheral portion of the under plate so as to form a magnetic gap between the side surface of the center pole and the yoke. It is a speaker.

[0009]

According to the present invention, the two magnets are arranged on the respective end surfaces of the center pole in a magnetically repulsive direction.
The top plate is arranged on the surface of one magnet, the under plate is arranged on the surface of the other magnet, the yoke is arranged on the outer periphery of the under plate, and a magnetic gap is formed between the side surface of the center pole. Since it is provided in the, the utilization efficiency of the magnet can be increased and the occurrence of rolling can be reduced.

[0010]

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

FIG. 1 is a structural sectional view of a speaker of a first embodiment according to the present invention. That is, in a cup-shaped frame 24 that constitutes the outer case of the speaker, an under plate 17 is provided at the bottom, a cylindrical magnet 15 is provided at the center of the under plate 17, and the magnet 15 has a cylindrical shape. A cylindrical center pole 13 is provided on the upper surface, and the cylindrical magnet 1 is provided on the upper surface of the center pole 13.
4 is provided, and a top plate 16 is provided on the upper surface of the magnet 14. Also, the under plate 17
A cylindrical yoke 18 is provided around the center pole 13
Is provided so as to form a magnetic gap with the side surface of the.

A voice coil 19 for generating a driving force in response to an electric signal is provided in the above-mentioned magnetic gap, and the voice coil 19 is attached to an end portion of a voice coil bobbin 20 and is driven by the voice coil 19. It is configured to move up and down. A damper 21 for supporting the voice coil bobbin 20 is provided between the midway portion of the voice coil bobbin 20 and the frame 24.
The diaphragm 22 is attached to the upper end of the
The outer peripheral portion of is attached to the frame 24 via the edge 23.

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

In FIG. 1, Tmu and Tmd are magnets 1, respectively.
4, 15 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
However, when moving upward from the neutral point of the amplitude, the moving distance (with the neutral point as the origin, the upward direction on the drawing is positive,
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), and conversely, when moving downward, the moving distance is −.
Up to (Tc-Tv) / 2, the volume of the voice coil 19 existing in the magnetic gap is constant, so the driving force is constant.

Since the magnets 14 and 15 are magnetized in a magnetically repulsive direction, the magnet 14 forms a magnetic path with the center pole 13, the yoke 18 and the top plate 16, and the magnet 15 has a center pole. A magnetic path is formed by 13, the yoke 18, and the under plate 17. Therefore, the top plate 16, the under plate 17, and the yoke 18
Become magnetically the same pole, and magnetic leakage to the outside of the magnetic circuit is extremely reduced. Further, since there are two magnetic paths as described above, the total 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 conventional case. The plate 17 becomes less magnetically saturated, and the diameter of the center pole 13 and the thickness Tu of the under plate 17 are reduced.
Can be made smaller. When the magnetic circuit has the above structure, there is almost no space inside the magnetic circuit except for the magnetic gap. Therefore, the magnetic leakage inside the magnetic circuit is extremely small except for the magnetic gap, and the magnetic utilization efficiency of the magnet is high. Become. The small space inside the magnetic circuit and the high utilization efficiency of the magnets make it possible to reduce the size and weight of the magnetic circuit.

Here, in order to increase only the utilization efficiency of the magnet, the height Ty of the yoke 18 is Tc + Tmu + Tmd + T.
It is preferable that the distance p is p, but if the distance Tvd between the voice coil 19 and the damper 21 becomes long, rolling easily occurs, and the yoke 18 or the center pole 13 and the like, the voice coil 19 and the voice coil bobbin 20 are generated in the magnetic gap. Will cause an abnormal sound to occur and a problem such as 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 9 and the damper 21 is shortened.

Next, FIG. 2 shows a structural sectional view of the speaker of the second embodiment. A big difference from the first embodiment is that the height Ty of the yoke 18 is Tc + Tmd <Ty <Tc + Tm.
The range is u + Tmd, and other configurations are the same.

The operation of this embodiment is exactly the same as that of the first embodiment, but the height Ty of the yoke 18 is equal to that of the top plate 16.
Since it is lower than the boundary surface between the magnet 14 and the magnet 14, the utilization efficiency of the magnet 14 is slightly decreased, the magnetic flux density in the magnetic gap is slightly decreased, and only the magnetic leakage is slightly increased. However, the voice coil 19 and the damper 2
Since the distance Tvd of 0 is shortened, the possibility of causing rolling is further reduced.

Next, FIG. 3 shows a structural cross-sectional view of the speaker of the third embodiment. A big difference from the first and second embodiments is that the height Ty of the yoke 18 is the same as Tc + Tmd. Other configurations are the same.

The operation of this embodiment is exactly the same as that of the first and second embodiments, but since the height Ty of the yoke 18 becomes equal to the boundary surface 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 also 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 shortened, the possibility of causing rolling is extremely small.

Next, FIG. 4 shows a structural sectional view of the speaker of the fourth embodiment. Also, the magnet 1 on the center pole
FIG. 5 shows a perspective view of a joint portion between the No. 4 and the top plate 16. The major difference from the previous embodiments is that the magnet 14
In order to improve the efficiency of use of the magnet 14, a plurality of recesses are provided on the top plate 16 side of the magnet 14 in a region including the outer peripheral portion at equal intervals, and the top plate 16 is fitted into the recesses of the magnet 14. The point is that the structure is provided with a convex portion. 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 the magnetic leakage to the outside of the magnetic circuit is reduced.

The yoke 18 is used in the fourth embodiment.
Although the height of the magnet is the same as that of the first embodiment, the magnet 14 and the top plate 16 are also applied to the second or third embodiment.
Can have a concavo-convex shape.

Further, in the above-mentioned fourth embodiment, the intervals between the concavities and convexities 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, according to the present invention, two magnets are arranged on both end faces of the center pole in a magnetically repulsive direction, and one magnet face is arranged. Top plate, an under plate arranged on the surface of the other magnet, and a yoke arranged on the outer peripheral portion of the under plate so as to form a magnetic gap between the side surface of the center pole and the under plate. Since it is provided, it has advantages that the utilization efficiency of the magnet is high, the occurrence of rolling can be reduced, and the size and weight are small.

[Brief description of drawings]

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

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

FIG. 3 is a structural sectional view of a speaker of a third embodiment according to 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 a speaker of a 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 under plate 18 yoke 19 voice coil 20 voice coil bobbin 21 damper 22 diaphragm 23 edge 24 frame

Claims (4)

[Claims] 1. A center pole, two magnets arranged in a direction that magnetically repels each surface of both end surfaces of the center pole, a top plate arranged on the surface of one of the magnets, and the other. Of an under plate disposed on the surface of the magnet, and a yoke disposed on an outer peripheral portion of the under plate so as to form a magnetic gap between the side surface of the center pole and the under plate. Characteristic speaker. 2. The height of the yoke is substantially the same as the height of the boundary surface between the one magnet and the center pole, and the height of the boundary surface between the one magnet and the top plate. The speaker according to claim 1, wherein the speaker is substantially at the same height and at the same height, or between the two heights. 3. The speaker according to claim 1, wherein one of the magnets is joined to the top plate, and an outer peripheral portion of the joining surface is formed in an uneven shape. 4. The speaker according to claim 3, wherein the concave and convex shapes are arranged at equal intervals.