JPS615697A - Voice coil bobbin - Google Patents

Abstract

PURPOSE:To obtain a bobbin light in weight, and high elasticity, excellent in heat resistance and moisture resistance, and abounds in radiating property by forming a bobbin to which a voice coil of a loudspeaker is wound, by an aluminum-lithium alloy foil containing lithium of <=15wt%. CONSTITUTION:A bobbin 13 to which a voice coil 14 is wound is formed by an aluminum Al-Li alloy foil whose lithium Li content is <=15wt%. An Al-Li alloy has such a tendency as a density drops, and an elastic modulus increases, when its Li content is increased. However, when the Li content exceeds 15wt%, the elastic modulus does not increase, therefore, as for the Li content, 15wt% is a limit. The bobbin formed by this Al-Li alloy foil is lighter than Al, has a higher rigidity than other material, and it is excellent in a heat resisting property and a radiating property, too. Also, since it is light in weight, and high in elasticity, a high band threshold frequency is raised, and a reproducing band is converted to a wide band.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an improvement in a voice coil bobbin used in a speaker for winding a voice coil inserted into a magnetic gap of a magnetic circuit to drive a diaphragm. It is.

[Technical background of the invention and its problems] The most common type of speaker is shown in FIG. 2, which will be explained below.

1 is a pole piece, and a magnetic circuit 5 is formed by sandwiching a magnet 3 between the yoke 2 and the plate 4.

A gasket 7 for attaching the speaker to a cabinet or the like and the outer periphery of a cone-shaped diaphragm 8 are attached to the outer periphery of the frame 6 attached to the plate 4, and a cylindrical bobbin 9 is fixed to the inner periphery of the diaphragm 8. The voice coil 11 wound around the bobbin 9 is inserted into the magnetic gap of the magnetic circuit 5.

A center cap 12 is attached to the center of the diaphragm 8, and a dash bar 10 is attached between the bobbin 9 and the frame 6.

Now, when the voice current flows through the voice coil 11, a driving force corresponding to the voice current is generated between the voice coil 11 and the magnetic flux passing through the magnetic gap, causing the voice coil 11 to vibrate. The vibrations are transmitted to the air and dissipated into the air as sound.

In this way, the bobbin 9, which has the function of transmitting the driving force generated in the voice coil 11 to the diaphragm 8 of the speaker, is lightweight and highly elastic in order to minimize the loss of driving force. In addition, necessary characteristics include sufficient resistance to Joule heat generated in the voice coil 11, ability to reliably dissipate heat from the driver unit, and excellent workability.

Conventionally used materials for the bobbin 9 include kraft paper, press-pan paper, aluminum foil, and plastic materials such as polyimide.

However, paper bobbins are lightweight and relatively elastic, but have the disadvantage of poor heat and moisture resistance, whereas metal bobbins and plastic bobbins, typically made of aluminum foil, have excellent heat and moisture resistance. The materials conventionally used have advantages and disadvantages, such as being heavier than paper bobbins, and some problems remain.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks of the conventional speaker voice coil bobbin, and provides a bobbin that is lightweight, highly elastic, has good heat resistance and moisture resistance, is rich in heat dissipation, and is excellent in workability. The purpose is to

[Embodiments of the invention]

In order to achieve the above-mentioned object, the present invention, as shown in FIG. 1, forms the bobbin 13 around which the voice coil 14 is wound with an aluminum-lithium alloy foil having a lithium content of 15% by weight or less.

That is, an aluminum-lithium alloy tends to have a lower density and an increased elastic modulus as the lithium content increases.

The table below shows lithium content of 0.1, 3, and 5.10% by weight.
The density and elastic modulus of the aluminum-lithium alloy are shown.

In this way, the higher the lithium content, the higher the density.
1 degree decreases, the elastic modulus increases, and the properties as a bobbin material become good.

However, when the lithium content is 15% by weight or more, the increase in elastic modulus tends to be slow, so the lithium content is limited to 15% by weight at most.

When the bobbin of the present invention is made of aluminum-lithium alloy foil with a lithium content of 5% by weight, its physical properties are compared with those of conventional bobbin materials as shown in the following table.

In this way, for example, a bobbin made of aluminum-lithium alloy foil containing 5% by weight of lithium is lighter than aluminum, more rigid than any other material, and has the same heat resistance as aluminum or polyimide. It has excellent heat dissipation properties.

Since it is lightweight and has high elasticity, the upper limit frequency is increased, and the reproduction band can be widened.

〔Effect of the invention〕

As described above, in the present invention, the bobbin around which the voice coil of the speaker is wound is formed of aluminum-lithium alloy foil containing 15% by weight or less of lithium, so that the bobbin can be made lightweight and highly rigid. can.

Therefore, it is possible to provide a wideband speaker with a high reproduction limit in the treble range, and since there is no vibration transmission loss, the efficiency of the speaker can be improved.

Furthermore, □It has good heat resistance and heat dissipation, so it can withstand high input and contributes to improving input resistance.It also has excellent moisture resistance, so it is not affected by humidity, and you can expect good playback at all times. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of an embodiment of the present invention, and FIG. 2 is a sectional view of a speaker. 9.13...Bobbin, 11.14...Voice coil.

Claims (1)

[Claims] A voice coil bobbin characterized in that an aluminum-lithium alloy having a lithium content of 15% by weight or less is made into a thin plate, shaped into a cylinder, and a voice coil is wound around the thin plate.