JPS5831799B2 - Manufacturing method of speaker diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a speaker diaphragm, particularly a dome-shaped diaphragm.

It is well known that a material with a large Young's modulus E and a small density ρ, in other words, a material with a large E/ρ is good as a material for a diaphragm for a speaker.

Materials with large E/ρ include beryllium and boron, but these materials, like aluminum and titanium, which have traditionally been used as diaphragm materials, can be made into thin plates by rolling or pressed into diaphragms. It has been difficult to use it as a diaphragm material because it cannot be processed into the shape of .

Therefore, in recent years, a material with a large E/ρ such as beryllium or boron is attached to the diaphragm substrate molded from aluminum, titanium, etc. by an appropriate means such as vacuum evaporation, sputtering, ion blating, or vapor phase growth to form a coating layer. A multilayer membrane diaphragm has been developed, and this has been filed by the same applicant as Utility Model Application No. 49-27263 and Japanese Patent Application No. 137760.

Since this diaphragm has a large E/ρ as a whole, it was possible to manufacture a speaker with good characteristics.

However, in the case of the above-mentioned diaphragm, the diaphragm base made of aluminum, titanium, etc. only increases the mass of the diaphragm;
Although completely unnecessary, there is currently no way to effectively remove this diaphragm substrate.

The present invention has been made in view of the above points, and an object thereof is to provide a method for manufacturing a speaker diaphragm in which a coating layer having a large Young's modulus and a low density is separated from a diaphragm substrate by a simple means. It is in.

Next, one embodiment of the present invention will be described with reference to the drawings.

1 has a diaphragm base made of glass, quartz, silicon, ceramic, or metal such as tungsten, molybdenum, tantalum, etc. in a dome shape, and has beryllium,
The coating layer 2 is formed by depositing a material such as boron, which has a high Young's modulus and a low density, by appropriate means such as vacuum deposition, sputtering, ion blasting, and vapor phase growth.

Note that among the methods for forming the coating layer 2, the vapor deposition method is superior because of its high coating efficiency.

The most suitable heating method during vapor deposition is a method using an electron beam.

Further, in order to improve the characteristics of the coating layer 2, particularly the boron coating layer, it is necessary to heat the diaphragm substrate 1.

By the way, when the temperature of the substrate 1 made of metal such as tungsten or molybten-tantalum is 300 to 650 DEG C., a film having an amorphous structure is obtained, and within this range, the characteristics of the deposited film, particularly the Young's modulus, do not become very high.

When the temperature is raised to around 650-700°C, small crystal grains begin to appear and the properties improve considerably, but in order to obtain properties close to those of the bulk, the substrate 1 must be heated to nearly 1000°C, but this is difficult for mass production etc. Considering the problem of 700
Heating to about 800°C is appropriate.

Heating of the substrate 1 is also necessary in cases other than vapor deposition means.

The coating layer 2 formed on the diaphragm base 1 by the above method is immersed in an etching solution such as hydrofluoric acid.

As a result, when the substrate 1 is made of glass, quartz, silicon, or ceramic, the periphery of the coating layer 2 is corroded, and when the substrate 1 is made of tungsten, molybdenum, or tantalum, the periphery of both the substrate 1 and the coating layer 20 is corroded. Parts are corroded.

Note that etching may be performed thinly over the entire surface.

Next, the material etched with the etching solution is immersed in water to allow water 3 to penetrate into the etched portion, and then the water 3 is frozen in liquid nitrogen.

Next, the substrate is heated to 500 to 600° C., but since the thermal expansion coefficients of the substrate 1 and the coating layer 2 are different due to this heating, the substrate 1 and the coating layer 2 are separated, and therefore, both are peeled off.

In addition, by re-manipulating the freezing and heating operations of water in the above, a more reliable separation can be performed.

Furthermore, when the coefficients of thermal expansion of the substrate 1 and the coating layer 2 are significantly different, for example, when the substrate 1 is made of tungsten or molybdenum and the coating layer 2 is made of boron, separation can be performed more reliably.

In the case of the diaphragm using the coating layer 2 manufactured above, especially the boron coating layer, it is necessary to provide toughness because the mechanical properties of boron are very fragile.

For this purpose, heat treatment may be performed after forming the boron coating layer 2 on the substrate 1, or zirconium, titanium, or aluminum may be added to boron.

When the above heat treatment was performed at 1300° C. at about 5 o'clock opening time, a very large effect was obtained.

Furthermore, when the above-mentioned soft material was added, the toughness was greatly improved by about 5 to 10%.

Note that if the addition amount is 30% or more, the characteristics of boron will be considerably weakened, and the characteristics of the diaphragm will deteriorate.

In the above embodiment, the coating layer 2 is formed on only one side of the diaphragm base 1 and is etched and freeze-expanded, but the coating layer 2 is formed on both sides of the base 10.
By forming the diaphragm and then performing the same operations as above, two diaphragms can be obtained at once.

Further, when performing etching, if ultrasonic waves are applied to the etching solution, etching can be performed quickly.

As described above, the present invention involves coating a diaphragm substrate with a material having a large Young's modulus and a small density to form a coating layer, and then immersing this in water to allow water to penetrate between the substrate and the coating layer. This water is frozen and expanded,
Since the coating layer is then peeled off from the base by heating due to the difference in coefficient of thermal expansion between the two, it is possible to easily and quickly manufacture a diaphragm made of only the coating layer.

[Brief explanation of drawings]

The figures are diagrams showing the steps in the method for manufacturing a speaker diaphragm according to the present invention, in which Fig. 1 is a cross-sectional view of a diaphragm substrate with a coating layer formed thereon, and Fig. 2 is a cross-sectional view of a case where a coating layer is formed on the diaphragm substrate, and Fig. 2 shows water between the same substrate and the coating layer. FIG. 3 is a cross-sectional view of the coating layer after it has been peeled off from the same as above. 1... Vibration plate base, 2... Coating layer, 3... Water.

Claims (1)

[Claims] 1. A diaphragm base made of glass, quartz, silicon, ceramic, or metal such as tungsten, molybdenum, tantalum, etc. into a diaphragm shape such as a dome, and a coating layer of a material with a high Young's modulus and low density such as boron or beryllium. After that, the peripheral part is etched with an etching solution, water is infiltrated between the substrate and the coating layer, the water is frozen and expanded by an appropriate means, and further heated to change the coefficient of thermal expansion of the substrate and the coating layer. A method of manufacturing a speaker diaphragm in which a diaphragm with a coating layer is obtained by peeling off the two layers based on the difference.