JPH0530596A - Speaker unit - Google Patents

Abstract

PURPOSE:To obtain a speaker unit improving the reduction of efficiency and having excellent sound pressure frequency characteristics by preventing the generation of a rolling phenomenon. CONSTITUTION:The sound pressure frequency characteristics can be improved by arranging a slider 14 to be moved in the axial direction of a shaft 11 vertically fixed to a center pole 12 of a magnetic circuit through a piezoelectric element 13 on the inner diameter face of a voice coil 7, extending the length of a contact part between the slider 14 and the shaft 11, preventing the generation of rolling, and narrowing a magnetic gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodynamic speaker unit used in audio equipment and the like.

[0002]

2. Description of the Related Art Conventionally, an electrodynamic speaker has been used as one of the electroacoustic transducers and is used for reproducing music and voice.

Hereinafter, a conventional speaker unit as described above will be described with reference to the drawings.

FIG. 4 shows a sectional structure of a conventional speaker unit. In FIG. 4, 1 is a magnet and 2 is a magnet.
Is an upper yoke provided on the upper surface of the magnet 1, 3 is a lower yoke provided on the lower surface of the magnet 1, and 4 is a lower yoke 3
5 is a magnetic pole formed between the inner peripheral surface of the upper yoke 2 and the outer peripheral surface of the center pole 4, 6 is a frame provided on the upper surface of the upper yoke 2, and 7 is a magnetic gap 5. A voice coil housed inside, 8 is a damper whose inner circumference is fixed to the voice coil 7 and whose outer circumference is fixed to the frame 6, 9 is a diaphragm whose inner circumference is fixed to the voice coil 7 and whose outer circumference is fixed to an edge which will be described later. The inner periphery is the edge fixed to the diaphragm 9, and the outer periphery is the edge fixed to the frame 6.

The operation of the speaker unit having the above structure will be described below. When an electric current is passed through the coil wound around the voice coil 7, the electric current becomes orthogonal to the magnetic field in the magnetic air gap 5, and a force is generated in the directions perpendicular to the magnetic field and the electric current according to Fleming's law. At this time, the damper 8 and the edge 10 support the voice coil 7 concentrically with the center pole 4,
When the diaphragm 9 vibrates, it acts as a spring in the amplitude direction to which a force is applied so that the midpoint of the upper yoke 2 in the thickness direction and the midpoint of the coil winding width of the voice coil 7 coincide with each other. When an alternating current is applied to the voice coil 7, the voice coil 7 and the diaphragm 9 vibrate while being supported by the damper 8 and the edge 10. As a result, the air is vibrated to generate compression waves, which are heard as sound.

[0006]

However, in the above-mentioned structure, the first problem is that the supporting force of the damper 8 and the edge 10 is asymmetrical, and the vibration occurs when the speaker unit is mounted on the box and reproduced. Due to the asymmetry of the back pressure applied to the plate 9, there is a problem that the vibration system does not perform ideal piston movement and causes a rolling phenomenon. Figure 5
Shows the movements of the diaphragm 9 and the voice coil 7 during rolling, as shown in the figure. As shown in the figure, when this phenomenon occurs, the voice coil 7 comes into contact with the upper yoke 2 and an abnormal noise is generated. In order to prevent the occurrence and the damage, the air gap 5 is widely provided in advance. The smaller the magnetic gap 5, the larger the magnetic flux density obtained, and the higher the efficiency, but the wider the magnetic gap 5, the lower the efficiency. Furthermore, when a rolling phenomenon occurs at a specific frequency, the entire diaphragm 9 does not move in phase but partially moves in opposite phase, as shown in FIG. Therefore, the sound pressure frequency characteristic is disturbed.

As a second problem, as shown in the force / displacement characteristic diagram of the damper shown in FIG. 6, since the relationship between the force and the displacement of the damper is not linear and also has hysteresis, the sound pressure frequency characteristic is There is a problem that harmonic distortion occurs.

The present invention is intended to solve the above problems,
An object of the present invention is to provide a speaker unit that can prevent a rolling phenomenon that leads to a reduction in efficiency and disturbance of sound pressure frequency characteristics, and can be configured without using a damper that causes distortion due to nonlinearity. To do.

[0009]

In order to achieve the above object, a speaker unit according to the present invention has a slider, which is vertically fixed to a center pole via a piezoelectric element, and has a slider that is movable in the axial direction of a shaft. It is provided on the surface.

[0010]

Therefore, according to the structure of the present invention, the voice coil always moves concentrically with the center pole, and by lengthening the length of the contact portion with the shaft of the slider, rolling is prevented and the magnetic gap is narrowed. You can Furthermore, since no damper is used, the sound pressure frequency characteristic is not disturbed by rolling with high efficiency, and distortion can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.
At the same time, the same parts as those in FIGS. 4 and 5 are designated by the same reference numerals, detailed description thereof will be omitted, and different points will be described.

FIG. 1 shows a sectional structure of a speaker unit according to an embodiment of the present invention.
Reference numeral 1 denotes a shaft vertically fixed to a center pole 12 via a piezoelectric element described later, 13 denotes a piezoelectric element having an outer peripheral portion fixed to the center pole 12 and an inner peripheral portion fixed to a lower portion of the shaft 11, 14 denotes the shaft 11 A slider provided on the inner peripheral surface of the voice coil 7 which is axially movable on the outer periphery of the slider, 15 has an inner periphery connected to the diaphragm 9, and an outer periphery of the frame
It is a suspension fixed to.

The operation of the speaker unit configured as described above will be described below. The pronunciation principle is the same as the conventional example. However, in the speaker unit of the present invention, only the suspension 15 takes charge of the movement of the spring. Further, the eccentricity of the voice coil 7 is prevented by the shaft 11
And the slider 14. In order to make the shaft 11 and the slider 14 slippery, at least one of the contact surfaces of the shaft 11 and the slider 14 is coated with a material having a small contact resistance such as a polymer compound such as a fluororesin, or these materials themselves are used. Form.

Further, the voice coil 7 and the slider 14 may be integrally formed in order to improve workability. A gap of several microns is provided between the shaft 11 and the slider 14, and some rolling occurs due to this gap, but as shown in FIG. 1, increasing the width X of the slider 14 is more effective. Can prevent rolling. Shaft 11 and slider 1
In order to reduce the dynamic friction at the contact surface with 4, the piezoelectric element 13 is provided below the shaft 11, and the shaft 11 is vibrated by applying a high frequency voltage outside the audible band to the electrode of the piezoelectric element 13.

In this embodiment, the case where the shaft 11 and the slider 14 slide on the surface has been described.
As shown in another embodiment, the bearing type slider 10 having a bearing structure may be used instead of the slider 14. Further, although the magnetic circuit is the outer magnet type, the same effect can be obtained in the inner magnet type and other systems.

FIG. 3 shows a comparison between the sound pressure frequency characteristic A by the speaker unit of the present invention and the sound pressure frequency characteristic B by the conventional speaker unit, and the same third harmonic distortion C by the speaker unit of the present invention and the conventional one. 3 is a diagram showing a comparison with the third harmonic distortion D by the speaker unit of FIG. As shown in the figure, the efficiency is improved, and the strain due to the nonlinearity of the bearing capacity of the damper can be reduced.

As described above, according to this embodiment, the voice coil includes the shaft 11 fixed vertically to the center pole 12 via the piezoelectric element 13 without using a damper and the slider 14 movable in the axial direction of the shaft 11. By providing it on the inner diameter surface of 7, the magnetic gap 5 can be narrowed and the damper can be eliminated.

[0018]

As is apparent from the above embodiment, the present invention provides a shaft fixed vertically to a center pole via a piezoelectric element and a slider movable in the axial direction of the shaft on the inner diameter surface of the voice coil. As a result, the magnetic gap is narrowed to improve efficiency, the disturbance of the sound pressure frequency characteristic due to rolling is eliminated, and by removing the damper, the distortion caused by the nonlinearity of the damper is reduced. Obtainable.

[Brief description of drawings]

FIG. 1 is a sectional view of a speaker unit according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a speaker unit according to another embodiment of the present invention.

FIG. 3 is a diagram comparing sound pressure frequency characteristics in an embodiment of the present invention and a conventional speaker unit.

FIG. 4 is a sectional view of a conventional speaker unit.

FIG. 5 is a cross-sectional view showing movements of a diaphragm and a voice coil during rolling of the speaker unit.

FIG. 6 is a force / displacement characteristic diagram of a damper in the speaker unit.

[Explanation of symbols]

6 frames 7 voice coil 9 diaphragm 11 shaft 12 Center pole 13 Piezoelectric element 14 Slider 15 suspension

Claims (4)

[Claims] 1. A frame fixed to a magnetic circuit, a vibration plate fixed to the frame via a suspension, a voice coil provided on the inner circumference of the vibration plate, and a center pole of the magnetic circuit via a piezoelectric element. A speaker unit having a vertically fixed shaft and a slider movable in the axial direction of the shaft provided on the inner diameter surface of the voice coil. 2. The speaker unit according to claim 1, wherein the slider and the voice coil are an integrated structure. 3. At least one of the slider and the shaft is made of a polymer compound which is a material having a small frictional resistance, or at least one of the contact surfaces of the slider and the shaft has a frictional resistance. The speaker unit according to claim 1, which is coated with a small material. 4. The speaker unit according to claim 1, wherein at least one of the slider and the shaft has a bearing structure.