JPH0670396A - Voice coil bobbin - Google Patents

Abstract

PURPOSE:To obtain the voice coil bobbin in which a high power for speaker is attained and the deterioration in the efficiency is prevented by constituting the bobbin main body with an alloy whose major component is magnesium. CONSTITUTION:The voice coil bobbin 4 is made of a magnesium alloy as its major component. The magnesium alloy has excellent heat conductivity, the electric resistance is nearly twice that of an aluminum, the density is smaller than that of the aluminum, then the weight is light as the feature. That is, in order to make the weight of the voice coil bobbin 4 light, the density of the magnesium is lower than that of the aluminum by nearly a multiple of 1.5, the thermal conductivity is lower by nearly a multiple of 1.4. Furthermore, the electric specific resistivity is higher by nearly a multiple of 1.6. Since the heat dissipation performance is improved, the input withstanding voltage to the voice coil 5 is increased and the occurrence of an overcurrent is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil bobbin for winding a voice coil.

[0002]

2. Description of the Related Art A voice coil bobbin has a function of winding a voice coil and vibrating a diaphragm by a magnetic reaction between the voice coil and a magnet.

An example of a device using such a voice coil bobbin is a dynamic speaker as shown in FIG. The dynamic speaker shown in the figure is provided with a pole yoke 1, a plate 2 and a magnet 3 which form a magnetic circuit.

A voice coil bobbin 4 around which a voice coil 5 is wound is arranged in a gap formed between the pole yoke 1 and the plate 2.

The voice coil bobbin 4 is fixed to the center of the diaphragm 6. Also, the voice coil bobbin 4 is
It is supported by the frame 8 via the damper 7. The outer peripheral edge of the diaphragm 6 is attached to the frame 8 via an edge 9. A gasket 10 is provided on the outer peripheral edge of the edge 9.
Is installed. A center cap 11 is arranged at the center of the diaphragm 6.

In such a structure, when a voice signal is supplied to the voice coil 5, the voice coil bobbin 4 vibrates due to the reaction between the magnetic flux generated from the voice coil 5 and the magnetic flux from the magnet 3. The vibration of the voice coil bobbin 4 causes the vibrating plate 6 to vibrate, thereby converting an electric signal into an acoustic signal.

[0007]

By the way, the voice coil bobbin 4 in the above-mentioned conventional dynamic speaker is often formed of paper or a resin material in order to reduce the weight of the voice coil bobbin 4 itself.

However, when the voice coil bobbin 4 is formed of such paper or resin material, the voice coil 5
Since the heat radiation of the heat generated by the electric signal supplied to the voice coil is poor, the withstand voltage input to the voice coil 5 cannot be increased, which hinders the high power of the dynamic speaker.

On the other hand, when the voice coil bobbin 4 is made of a metal capable of improving heat dissipation, for example, an aluminum alloy, the withstand voltage can be increased, but the eddy current is generated to cause a loss of electric energy. As a result, the sensitivity lowers near the minimum resonance frequency f0, resulting in lower efficiency.

The present invention has been made in consideration of such a situation, and aims to increase the power of a speaker, and
It is an object of the present invention to provide a voice coil bobbin capable of preventing a decrease in efficiency.

[0011]

In order to achieve the above object, the present invention is a voice coil bobbin for winding a voice coil, wherein the bobbin main body is made of an alloy containing magnesium as a main component. To do.

[0012]

In the voice coil bobbin of the present invention, the bobbin body is made of an alloy containing magnesium as a main component. Magnesium alloy has good thermal conductivity, has an electric resistance of about twice that of aluminum, and is lighter in density than aluminum.

Therefore, by using the magnesium alloy having the above characteristics as the bobbin material, the heat dissipation is improved, so that the withstand voltage can be increased and the generation of eddy current can be reduced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of one embodiment of the present invention will be described below with reference to the drawings. The voice coil bobbin described below is applied to the dynamic speaker shown in FIG. 1, for example. However, the dynamic speaker in the present embodiment is common to that in FIG. 1, and therefore its illustration and description are omitted.

First, the voice coil bobbin 4 in this embodiment is composed mainly of magnesium alloy. Here, the magnesium alloy has a feature that it has good thermal conductivity, an electric resistance that is about twice that of aluminum, and is lighter because it is smaller in density than aluminum.

Therefore, by using the magnesium alloy having such a feature as the bobbin material, the heat radiation property is improved, so that the withstand voltage can be increased and the generation of eddy current can be reduced.

That is, the physical properties of magnesium as compared with aluminum are as shown in FIG.

As shown in the figure, the voice coil bobbin 4
It can be seen that the density for reducing the weight is about 1.5 times lower in the case of magnesium than in aluminum. It can be seen that the thermal conductivity of magnesium is about 1.4 times lower than that of aluminum. It can be seen that the electrical resistivity of magnesium is about 1.6 times higher than that of aluminum.

FIG. 3 shows an example in which the temperature of the voice coil when the bobbin material is magnesium is compared with that when the bobbin material is glass imide and aluminum.

As shown in the figure, when 100 W is input, the temperature of the voice coil is lower in the order of aluminum <magnesium <glass imide.

It can be seen that at the time of inputting 200 W, the temperature of the voice coil is low in the order of aluminum <magnesium <glass imide.

It can be seen that at the time of input of 150 W, the temperature of the voice coil is lower in the order of aluminum <magnesium <glass imide.

From the above, when the bobbin material is made of magnesium, the temperature of the voice coil is higher than that of aluminum, but the difference is about 8 ° C. at the maximum input of 150 W, which is higher than that of glass imide. As can be seen, there is a difference of 40 ° C. at the time of inputting 150 W, so it is understood that it is sufficient to improve the heat dissipation.

FIG. 4 shows an example in which the output sound pressure frequency characteristics when the bobbin material is magnesium are compared with those when the bobbin material is glass imide and aluminum.

As shown in the figure, focusing on the frequencies of 60 Hz to 70 Hz, it can be seen that the sound pressure level increases in the order of glass imide>magnesium> aluminum. Further, as understood from the impedance characteristics, the order is glass imide>magnesium> aluminum.

In other words, this indicates the order of loss of electric energy, and the loss decreases in the order of glass imide <magnesium <aluminum.

As described above, in this embodiment, the magnesium alloy is used as the bobbin material because it has good thermal conductivity, an electric resistance of about twice that of aluminum, and is lighter in density than aluminum. Since the heat dissipation is improved, the input withstand voltage can be increased, and the generation of eddy current can be reduced. Therefore, it is possible to increase the power of the speaker and prevent the efficiency from decreasing.

In this embodiment, the case where the present invention is applied to the dynamic speaker has been described, but the present invention is not limited to this example, and the present invention may be applied to a coil bobbin used in a dynamic microphone.

[0029]

As described above, according to the voice coil bobbin of the present invention, the heat conductivity is good, the electric resistance is about twice as high as that of aluminum, and the density is smaller than that of aluminum, so that it is light. By using a certain magnesium alloy as the bobbin material, the heat dissipation can be improved, the withstand voltage can be increased, and the generation of eddy current can be reduced. The decrease can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional dynamic speaker.

FIG. 2 is a diagram showing main physical properties of a bobbin material in a voice coil bobbin of the present invention in comparison with aluminum.

FIG. 3 is a diagram showing a case where the temperature of the voice coil when the bobbin material of FIG. 2 is magnesium is compared with the temperature of the voice coil when the bobbin material is glass imide and aluminum.

FIG. 4 is a diagram showing a case where the output sound pressure frequency characteristics when the bobbin material of FIG. 2 is magnesium is compared with the case where the bobbin material is glass imide and aluminum.

[Explanation of symbols]

 4 voice coil bobbin 5 voice coil

Claims (1)

[Claims] 1. A voice coil bobbin for winding a voice coil, wherein the bobbin main body is made of an alloy containing magnesium as a main component.