JPH0614394A - Loudspeaker - Google Patents

Abstract

PURPOSE:To prevent a magnetic fluid from jumping out of a magnetic pole gap along with a vertical motion of a voice coil, and to sufficiently display an effect of a damper structure using the magnetic fluid. CONSTITUTION:In the loudspeaker having a magnetic circuit system 1 consisting of a yoke 4, magnetic 5 fixed to the yoke 4, a pole 6 arranged on the yoke 4, a plate 7 arranged with the inside peripheral surface faced across from the pole 6, and a magnetic pole gap formed between the pole 6 and the plate 7, a voice coil 2 which is arranged in the magnetic pole gap of the magnetic circuit system 1 and moves vertically in the magnetic pole gap 8 by a direction and strength and weakness of a supplied voice current, and a diaphragm 3 for converting a motion of the voice coil 2 to an audio, this loudspeaker is constituted by interposing a magnetic fluid 11 in the magnetic pole cavity 8, and forming spiral grooves 12 and 13 with the center axis (center line m) of the pole 6 as an axis direction on the surface across from the magnetic pole gap 8 of the pole 6 and the plate 7, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker, and more particularly, it is suitable for use as a cone-type dynamic speaker in which a diaphragm has a cone shape and sounds are directly emitted from the diaphragm to a space.

[0002]

2. Description of the Related Art Generally, a cone-shaped dynamic speaker is basically composed of a magnetic circuit section 51, a voice coil 52 and a diaphragm 53, as shown in FIG.
The magnetic circuit portion 51 includes a disk-shaped yoke 54, a ring-shaped magnet 55 fixed on the yoke 54, and a pole 56 integrally formed with the yoke 54 so as to stand up at the center of the yoke 54. A plate 57 is fixed to the upper surface of the magnet 55 and has an inner peripheral surface opposed to the pole 56, and a magnetic pole gap 58 formed between the pole 56 and the plate 57.

The voice coil 52 is a magnetic circuit section 51.
Is arranged in the magnetic pole gap 58 and moves up and down in the magnetic pole gap 58 depending on the direction and strength of the supplied audio current. The vibrating plate 53 is formed in a cone shape, vibrates by the vertical movement of the voice coil 52, and radiates as sound directly to the space.

At present, the magnetic poles are arranged so that the amplitude of the voice current flowing through the voice coil 52 and the magnitude of the electromagnetic force generated by the voice current, that is, the amount of vertical movement of the voice coil 52 are substantially proportional to each other. Magnetic fluid 61 in the space 58
Is applied. The magnetic fluid 61 is made of, for example, silicone (silicon resin) having fluidity and containing metal powder. By appropriately adjusting the viscosity of the magnetic fluid 61, the amount of vertical movement of the voice coil 52 with respect to the amplitude of the voice current can be set in a substantially proportional relationship. Further, the magnetic fluid 61
By coating the inside of the void 58 with heat, the heat from the voice coil 52 due to the conduction of the voice current is efficiently absorbed by the pole 56.
And it can be transmitted to the plate 57, so that the effect as a so-called heat sink can be obtained.

[0005]

By the way, in the above-mentioned conventional speaker, the opposing surfaces of the pole 56 and the plate 57 are processed into substantially mirror surfaces, and the magnetic fluid 61 is applied to the mirror surfaces. Thus, the magnetic fluid 61 is interposed in the void 58. In this case, since the gap 58 is very narrow, the magnetic fluid 61 will not drop due to the influence of gravity. However, when the up and down movement of the voice coil 52 is performed with a relatively large amplitude, the magnetic fluid 61 jumps out of the void 58, and the magnetic fluid 61 gradually disappears.

Therefore, a method of preventing the pop-out by increasing the viscosity of the magnetic fluid 61 can be considered. However, the magnetic fluid 61 itself becomes a resistance against the vertical movement of the voice coil 52, resulting in a voice current. It becomes difficult to set the amount of vertical movement of the voice coil 52 with respect to the amplitude of the above-mentioned relationship in a substantially proportional relationship, which deteriorates various characteristics of the speaker.

The popping out phenomenon of the magnetic fluid 61 is more pronounced in the voice coil 5 than in the high-frequency speaker (tweeter).
In the present situation, the bass speaker does not have the damper structure using the magnetic fluid 61, because the bass speaker has a large amount of up and down movement (woofer).

The present invention has been made in view of the above problems, and an object thereof is to prevent the magnetic fluid from jumping out from the magnetic pole gap due to the vibration of the voice coil. Another object of the present invention is to provide a speaker that can fully exert the effect of the damper structure.

[0009]

The present invention comprises a yoke 4 and
The magnet 5 fixed to the yoke 4, the pole 6 arranged on the yoke 4, the plate 7 arranged so that the inner peripheral surface faces the pole 6, the pole 6 and the plate 7
A magnetic circuit portion 1 including a magnetic pole gap 8 formed between
In the speaker having the voice coil 2 arranged in the magnetic pole gap 8 of the magnetic circuit unit 1 and the diaphragm 3, the magnetic fluid 11 is interposed in the magnetic pole gap 8 and the magnetic pole gap of the pole 6 and / or the plate 7 is provided. The groove 12 and / or 13 is formed on the surface opposite to 8. This groove 12 and / or 13
For, a spiral groove having the center axis (center line m) of the pole 6 as the axial direction can be used.

[0010]

In the speaker according to the present invention, the magnetic flux passes in the radial direction from the pole 6 to the plate 7 or from the plate 7 to the pole 6 in the magnetic pole gap 8 of the magnetic circuit section 1. When a voice current is passed through the voice coil 2 in this state, an electromagnetic force in the vertical direction acts on the voice coil 2 by the same principle as that of the motor, and the voice coil 2 is moved in the magnetic pole gap 8 in accordance with the direction and strength of the voice current. Move up and down. At this time, the magnetic fluid 11 present in the magnetic pole gap 8 is
In the normal case, the voice coil 2 will move out of the magnetic pole gap 8 as the voice coil 2 moves up and down.
The magnetic fluid 11 will escape into the grooves 12 and / or 13 formed on the surface of the pole 6 and / or the plate 7 facing the magnetic pole gap 8 without jumping out from the magnetic pole gap 8. That is, the protrusion of the magnetic fluid 11 from the magnetic pole gap 8 due to the vertical movement of the voice coil 2 is restricted by the grooves 12 and / or 13.

In particular, when the grooves 12 and / or 13 are spiral grooves, the magnetic fluid 11 which has escaped to the spiral grooves 12 and / or 13 as the voice coil 2 moves up and down is formed in the spiral grooves 12 and / or 13. Guide, the voice coil 2 moves vertically in accordance with the movement of the voice coil 2. Therefore, the voice coil 2 smoothly moves in the magnetic pole gap 8, and the amplitude of the supplied voice current (magnitude of electromagnetic force). The amount of up-and-down movement according to is to be performed almost faithfully. From this, it becomes easy to set the amount of vertical movement of the voice coil 2 to the amplitude of the voice current in a substantially proportional relationship. Further, as described above, since the magnetic fluid 11 is prevented from jumping out, it is possible to efficiently transfer the heat from the voice coil 2 accompanying the conduction of the voice current to the pole 6 and the plate 7 through the magnetic fluid 11.

[0012]

Embodiments of the speaker according to the present invention, in particular, an embodiment of a cone type dynamic speaker will be described below with reference to FIGS.

As shown in FIG. 1, this speaker is basically composed of an outer magnet type magnetic circuit section 1, a voice coil 2 and a diaphragm 3. The magnetic circuit portion 1 is integrally formed with a yoke 4 formed in a disk shape, a ring-shaped magnet 5 fixed on the yoke 4, and a yoke 4 which is raised at the center of the yoke 4. From the pole 6, the ring-shaped plate 7 fixed to the upper surface of the magnet 5 and arranged so that the inner peripheral surface faces the pole 6, and the magnetic pole gap 8 formed between the pole 6 and the plate 7. It is configured. The magnet 5
For example, a cast magnet whose composition standard is Fe-Al-Ni is used. In addition, the yoke 4 and the pole 6
The plate 7 and the plate 7 are made of pure iron, for example.

The voice coil 2 is arranged in the magnetic pole gap 8 of the magnetic circuit section 1 and moves up and down in the magnetic pole gap 8 depending on the direction and strength of the supplied voice current. The vibrating plate 3 is formed in a cone shape, vibrates by the vertical movement of the voice coil 2, and radiates directly as sound to the space.

The voice coil 2 is constructed by winding a copper wire on a bobbin 9 made of paper, for example, for several tens of turns. By attaching the bobbin 9 to a frame (not shown) via a spiral damper 10, Voice coil 2
Are held in the magnetic pole gap 8. The winding width of the voice coil 2 is set larger than the width of the plate 7. When a voice current flows through the voice coil 2, an electromagnetic force in the direction of the arrow acts on the voice coil 2 by the same principle as that of a motor, and the voice coil 2 moves up and down in the magnetic pole gap 8 according to the direction and strength of the voice current. . This voice coil 2
The vertical movement of is transmitted to the diaphragm 3, and the vibration is directly radiated into the space as sound.

In the present embodiment, the amplitude of the voice current flowing through the voice coil 2 and the magnitude of the electromagnetic force generated by the voice current, that is, the amount of vertical movement of the voice coil 2 have a substantially proportional relationship. In the magnetic pole gap 8, the magnetic fluid 1
1 is applied. The magnetic fluid 11 is made of, for example, silicone (silicon resin) having fluidity and containing metal powder. By appropriately adjusting the viscosity of the magnetic fluid 11, it becomes possible to set the amount of vertical movement of the voice coil 2 with respect to the amplitude of the voice current in a substantially proportional relationship. Further, the magnetic fluid 11 is filled with the void 8
By coating the inside, heat from the voice coil 2 due to energization of voice current can be efficiently applied to the pole 6 and the plate 7.
The effect as a so-called heat sink can be obtained.

Further, in this embodiment, as shown in the enlarged view of the insertion of FIG. 1 and FIG. 2, the surfaces of the pole 6 and the plate 7 which face each other, that is, the outer surface of the pole 6 and the inner surface of the plate 7. In addition, for example, a clockwise spiral groove 12 whose axial direction is the central axis of the pole 6 (see the central line m), respectively.
And 13 are formed. In particular, the entire width of the spiral groove 12 formed on the pole 6 side is set to be substantially the same as the winding width of the voice coil 2.

Next, the operation of the speaker according to this embodiment will be described. First, in the magnetic pole gap 8 of the magnetic circuit unit 1,
The magnetic flux passes in the radial direction from the pole 6 to the plate 7 or from the plate 7 to the pole 6. When a voice current is passed through the voice coil 2 in this state, an electromagnetic force in the vertical direction acts on the voice coil 2 by the same principle as that of the motor, and the voice coil 2 is moved in the magnetic pole gap 8 in accordance with the direction and strength of the voice current. Move up and down. At this time, the magnetic fluid 11 present in the magnetic pole gap 8 normally jumps out of the gap 8 as the voice coil 2 moves up and down. In the present embodiment, the magnetic fluid 11 is Without jumping out from the gap 8, it escapes into the spiral grooves 12 and 13 formed on the surfaces of the pole 6 and the plate 7 facing each other. That is, the protrusion of the magnetic fluid 11 from the magnetic pole gap 8 due to the vertical movement of the voice coil 2 causes the spiral groove 12 to move.
And 13 will be regulated.

In particular, the magnetic fluid 11 that has escaped to the spiral grooves 12 and 13 as the voice coil 2 moves up and down is guided by the spiral grooves 12 and 13 and moves vertically according to the movement of the voice coil 2. Voice coil 2
Moves smoothly in the void 8 and substantially faithfully moves up and down by an amount corresponding to the amplitude of the supplied voice current (magnitude of electromagnetic force). From this, it becomes easy to set the vibration amount of the voice coil 2 to the amplitude of the voice current in a substantially proportional relationship.

Further, as described above, since the magnetic fluid 11 is prevented from jumping out, the heat from the voice coil 2 accompanying the conduction of the voice current can be efficiently transmitted to the pole 6 and the plate 7 through the magnetic fluid 11. You can The twist angle of each spiral groove 12 and 13 is set to such an angle that the magnetic fluid 11 that has entered the spiral grooves 12 and 13 can follow the movement of the voice coil 2 and preferably the amplitude of the voice current. The amount of vertical movement of the voice coil 2 is set so as to have a substantially proportional relationship with respect to.

As described above, according to the speaker of this embodiment, the magnetic pole gap 8 formed between the pole 6 and the plate 7 is formed.
The magnetic fluid 11 is interposed inside the pole 6 and the plate 7
Since the spiral grooves 12 and 13 are respectively formed on the surfaces of the magnetic fluid which face each other, the magnetic fluid 11 can be prevented from jumping out from the magnetic pole gap 8 when the voice coil 2 moves up and down. The effect of the damper structure that has been used can be fully exerted. Therefore, various characteristics of the speaker can be improved, and moreover, the magnetic fluid 1 described above.
The damper structure using 1 can be adopted also for the bass speaker, and the performance improvement of the bass speaker can be promoted.

In the above embodiment, the pole 6 and the plate 7
The example in which the spiral grooves 12 and 13 are provided is shown in
Besides, the spiral groove 12 may be provided only on the surface (outer diameter surface) of the pole 6 facing the plate 7, or the plate 7
The spiral groove 13 may be provided only on the surface (inner diameter surface) facing the pole 6 in.

Further, in the above-mentioned embodiment, the spiral grooves 12 and 13 are provided on the pole 6 and the plate 7, respectively. However, as shown in FIG. 3, instead of the spiral grooves 12 and 13, a normal annular shape is used. The grooves 21 and 22 may be provided. Also in this case, the magnetic fluid 11 can be effectively prevented from jumping out. However, it is inferior to the spiral grooves 12 and 13 in that the voice coil 2 is smoothly moved. Also, the voice coil 2
As shown in FIG. 4, a rectangular cross section may be used. In this case, the magnetic fluid 1 is better than the one with a circular cross section.
There is less resistance to 1.

In the above embodiment, the magnetic circuit portion of the speaker is applied to the so-called outer magnet type magnetic circuit portion 1 in which the magnet 5 is arranged outside the pole 6.
In addition, as shown in FIG. 5, a magnet 5 is fixed to the center of the bottom of a yoke 4 having a bottomed cylindrical shape, a pole 6 is fixed to the upper surface of the magnet 5, and an inner peripheral surface faces the pole 6. It is also applicable to the so-called inner magnet type magnetic circuit unit 1 configured by fixing the plate 7 thus arranged to the upper end of the yoke 4.

[0025]

As described above, according to the speaker of the present invention, the magnetic fluid is interposed in the magnetic pole gap formed between the pole and the plate, and the magnetic pole gap is formed on the surface of the pole and / or the plate facing the magnetic pole gap. Since the groove (spiral groove) is formed, it is possible to prevent the magnetic fluid from jumping out of the magnetic pole gap due to the vertical movement of the voice coil, and to sufficiently exert the effect of the damper structure using the magnetic fluid. You can

As a result, the amount of vertical movement of the voice coil with respect to the amplitude of the voice current supplied to the voice coil can be set in a substantially proportional relationship, and the heat from the voice coil accompanying the conduction of the voice current is transferred to the magnetic fluid. Can be efficiently transmitted to the pole and the plate, and various characteristics of the speaker can be improved. Moreover, the damper structure using the magnetic fluid can be adopted for the bass speaker.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a speaker according to the present invention, in particular, a cone-type dynamic speaker with a partially broken structure.

FIG. 2 is a partially cutaway perspective view showing the shapes of a pole and a plate of the speaker according to the present invention.

FIG. 3 is an enlarged cross-sectional view showing another shape of the groove formed in the pole and plate of the speaker according to the present invention.

FIG. 4 is an enlarged cross-sectional view showing another shape of the voice coil of the speaker according to the present invention.

FIG. 5 is a cross-sectional view of a main part showing another configuration of the speaker according to the present invention with a part thereof cut away.

FIG. 6 is a sectional view of an essential part showing a partially broken configuration of a speaker according to a conventional example.

[Explanation of symbols]

 1 magnetic circuit part 2 voice coil 3 diaphragm 4 yoke 5 magnet 6 pole 7 plate 8 magnetic pole gap 9 bobbin 10 spiral damper 11 magnetic fluid 12, 13 spiral groove

Claims (2)

[Claims] 1. A yoke, a magnet fixed to the yoke, a pole arranged on the yoke, a plate arranged so that an inner peripheral surface faces the pole, and a space between the pole and the plate. In a speaker having a magnetic circuit part including a magnetic pole gap, a voice coil arranged in the magnetic pole gap of the magnetic circuit part, and a diaphragm, a magnetic fluid is interposed in the magnetic pole gap, A speaker is characterized in that a groove is formed on a surface of the plate facing the magnetic pole gap. 2. The speaker according to claim 1, wherein the groove is formed in a spiral shape.