JPH04248800A - Speaker unit - Google Patents

Abstract

PURPOSE:To improve the disturbance in a sound pressure frequency characteristic and the deterioration in the efficiency and further to reduce the distortion due to nonlinearity of a support force of a damper by preventing rolling of the vibration system in a dynamic speaker unit. CONSTITUTION:A slider 19 movable in the axial direction of a shaft 17 fixed perpendicularly to a center pole 14 of a magnetic circuit is provided to an inner diameter face of a voice coil 18, the voice coil 18 is connected to a frame 16 via a diaphragm 20 and an edge 21 to remove a damper as the structure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker unit for an electrodynamic speaker.

0002

2. Description of the Related Art Conventionally, there has been an electrodynamic speaker as one type of electroacoustic transducer, and it has been used to reproduce music and sounds.

The conventional speaker unit mentioned above will be explained below with reference to the drawings.

FIG. 4 shows a structural sectional view of a conventional speaker unit. In (Fig. 4), 1 is a magnet, 2 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, 4 is a center pole continuous with the lower yoke 3, and 5 is a magnetic gap 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;
8 is a voice coil housed in the magnetic gap 5; 8 is a damper whose inner periphery is fixed to the voice coil 7; the outer periphery is fixed to the frame 6; 9 is a vibration whose inner periphery is fixed to the voice coil 7; and whose outer periphery is fixed to an edge to be described later. The plate 10 is an edge whose inner circumference is fixed to the diaphragm 9 and the outer circumference is fixed to the frame 6.

The operation of the speaker unit configured as described above will be explained below. When a current is passed through the coil wound around the voice coil 7, the current is perpendicular to the magnetic field within the magnetic gap 5, and according to Fleming's law, a force is generated in a direction perpendicular to both the magnetic field and the current. At this time, the damper 8 and the edge 10 support the voice coil 7 so as to be concentric with the center pole 4,
When the diaphragm 9 vibrates, it acts as a spring in the amplitude direction that applies a force so that the midpoint of the thickness direction of the upper yoke 2 and the midpoint of the coil winding width of the voice coil 7 coincide. voice coil 7
When an alternating current is applied to the voice coil 7 and the diaphragm 9, the voice coil 7 and the diaphragm 9 vibrate while being supported by the damper 8 and the edge 10. This causes the air to vibrate and generate compressional waves, which can be heard as sound.

[0006]

[Problems to be Solved by the Invention] However, with the above configuration, the first problem is the asymmetry of the supporting force of the damper 8 and the edge 10, and when the speaker unit is attached to a box and played back, the diaphragm Due to the asymmetry of the back pressure applied to the piston, the vibration system may not move the piston ideally, causing a rolling phenomenon. (Figure 5) is a diagram showing the movement of the diaphragm and voice coil during rolling with arrows. As shown in the figure, when this phenomenon occurs, the voice coil comes into contact with the yoke, causing abnormal noise. To prevent damage, a wide magnetic gap is provided in advance. The narrower the magnetic gap, the higher the magnetic flux density and the higher the efficiency, but the wider the gap, the lower the efficiency. Furthermore, when a rolling phenomenon occurs at a specific frequency, the entire diaphragm does not move in phase, but partially moves in antiphase, as shown in FIG. 5. Therefore, disturbances occur in the sound pressure frequency characteristics.

The second problem is that, as shown in the force-displacement characteristics of the damper in FIG. 6, the relationship between the force and displacement of the damper is not linear and has hysteresis, so the sound pressure frequency characteristics harmonic distortion occurs.

[0008] In view of the above-mentioned problems, the present invention solves the problem of reducing efficiency,
To provide a speaker unit that can prevent rolling phenomena that lead to disturbances in sound pressure frequency characteristics, and can have a configuration that does not use a damper that causes distortion due to nonlinearity.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the speaker unit of the present invention is provided with a slider movable in the axial direction of a shaft fixed perpendicularly to a center pole on the inner diameter surface of the voice coil, and a damper. The structure has been removed.

0010

[Operation] With this configuration, the voice coil always moves concentrically with the center pole, and by increasing the length of the contact part with the slider shaft, rolling is prevented.
The magnetic gap can be narrowed. Furthermore, since no damper is used, efficiency is high, there is no disturbance in sound pressure frequency characteristics due to rolling, and distortion is reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(FIG. 1) shows a structural cross section of a speaker unit in one embodiment of the present invention. In FIG. 1, 11 is a magnet, 12 is an upper yoke provided on the upper surface of the magnet 11, 13 is a lower yoke provided on the lower surface of the magnet 11, 14 is a center pole continuous with the lower yoke 13, and 15 is a lower yoke provided on the lower surface of the magnet 11. is a magnetic gap formed between the inner circumferential surface of the upper yoke 12 and the outer circumferential surface of the center pole 14;
6 is a frame provided on the upper surface of the upper yoke 12, 17 is a shaft fixed perpendicularly to the center pole 14, 18 is a voice coil housed in the magnetic gap 15, and 19 is the outer circumference of the shaft 17 and moves in its axial direction. A slider 20 is a diaphragm whose inner periphery is connected to the voice coil 18 and an outer periphery to an edge to be described later. 21 is a diaphragm whose inner periphery is connected to the diaphragm 20 and whose outer periphery is connected to the voice coil 18. This is an edge fixed to the frame 16.

The operation of the speaker unit configured as described above will be explained below.

The principle of pronunciation is the same as that of the conventional example. However, only the edge 21 is responsible for the spring function. Furthermore, eccentricity of the voice coil 18 is prevented by the shaft 17 and the slider 19. shaft 17 and slider 19
In order to make it easier to slide, the contact surface of at least one of the shaft 17 and the slider 19 is coated with a material with low contact resistance such as a polymer compound such as fluororesin, or is made of the above-mentioned material itself. Further, the voice coil 18 and the slider 19 are integrally constructed to improve workability. A gap of several microns is provided between the shaft 17 and the slider 19. Although some rolling occurs due to this gap, the slider width shown in (Fig. 1)
By increasing the length, rolling can be more effectively prevented.

As described above, according to this embodiment, a shaft is fixed perpendicularly to the center pole without using a damper, and a slider movable in the axial direction of the shaft is provided on the inner diameter surface of the voice coil. It is also possible to narrow the air gap and eliminate the damper.

(FIG. 3) shows the sound pressure frequency characteristic A of the present embodiment, the sound pressure frequency characteristic B of the conventional method, the third harmonic distortion C of the present embodiment, and the third harmonic of the conventional method. It is a diagram comparing distortion D. As is clear from FIG. 3, according to the speaker unit of this embodiment, efficiency can be improved and distortion caused by non-linearity of the supporting force of the damper can also be reduced.

In this embodiment, it is assumed that the shaft and slider slide on a surface, but a method using a bearing as shown in FIG. You may also use Further, although the magnetic circuit has been described using an outer magnetic type, similar effects can be obtained by using an inner magnetic type or other type of magnetic circuit.

[0018]

[Effects of the Invention] Since the present invention has a shaft fixed perpendicularly to the center pole and a slider movable in the axial direction of the shaft on the inner diameter surface of the voice coil, the magnetic gap is narrowed and efficiency is improved. Disturbances in the sound pressure frequency characteristics due to rolling are also eliminated, and by removing the damper, it is possible to reduce distortion caused by the nonlinearity of the damper.

[Brief explanation of the drawing]

FIG. 1 is a structural sectional view of a speaker unit in one embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a sliding method between a shaft and a slider of a speaker unit in another embodiment of the present invention.

FIG. 3 is a sound pressure frequency characteristic diagram of the present invention and a conventional example.

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

FIG. 5 is a diagram showing the movement of a diaphragm and a voice coil during rolling of a speaker unit in a conventional example.

FIG. 6 is a force-displacement characteristic diagram of a damper of a speaker unit in a conventional example.

[Explanation of symbols]

11 Magnet 12 Upper yoke 13 Lower yoke 14 Center pole 15 Magnetic air gap 16 Frame 17 Shaft 18 Voice coil 19 Slider 20 Diaphragm 21 Edge

Claims (5)

[Claims] 1. A frame fixed to a magnetic circuit, a diaphragm fixed to the frame via a suspension, a voice coil provided on the inner periphery of the diaphragm, and a diaphragm arranged perpendicularly to a center pole of the magnetic circuit. A speaker unit comprising a fixed shaft and a slider movable in the axial direction of the shaft, the slider being provided on an inner diameter surface of the voice coil. 2. The speaker unit according to claim 1, wherein the slider and the voice coil are an integral structure. 3. The speaker unit according to claim 1, wherein at least one of the slider and the shaft is made of a polymer compound or a polymer material that is a material with low frictional resistance. 4. The speaker unit according to claim 1, wherein at least one of the contact surfaces between the slider and the shaft is coated with a polymer compound or polymer material that is a material with low frictional resistance. 5. The speaker unit according to claim 1, wherein at least one of the slider and the shaft has a bearing structure.