JPH0728477B2 - Vibration plate for audio equipment and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improvement of a diaphragm of an audio device, and more particularly to improvement of a diaphragm using ceramics and a method of manufacturing the same.

In recent years, attention has been paid to the high Young's modulus of ceramics, and a ceramic diaphragm made of alumina, silicon nitride, etc., or a composite diaphragm made by layering the ceramic on the surface of a metal such as magnesium, titanium, aluminum, etc., has also been proposed and put into practical use. Some have been done.

However, as is well known, since ceramic is a material that is extremely poor in brittleness, it must be achieved by compounding it with a metal for practical use.

However, such compounding has a drawback that the high Young's modulus, which is a characteristic of ceramics, is impaired, and if the adhesive strength with a metal is not sufficient, peeling of the adhesive occurs and a problem occurs in the input resistance characteristics.

Further, a vibration plate has been proposed in which ceramics and highly elastic fibers are sprayed and mixed by a thermal spraying method, but the deposited layer of ceramics by thermal spraying is insufficient in terms of Young's modulus because the void ratio is large.

Therefore, the present invention relates to a diaphragm having an extremely high Young's modulus in which a diaphragm is formed of sintered ceramics and whiskers, and a method for manufacturing the diaphragm, and the embodiments will be described in detail below.

(1) Dispersion liquid A was prepared by adding silicon carbide whiskers with a length of 200 to 300 μm and a wire diameter of about 1 μm to water at a concentration of 0.3 g /, and irradiating ultrasonic waves at 18 Kz to uniformly disperse the whiskers.
To get

(2) After mixing silicon nitride and magnesium oxide (5 wt%) as a sintering aid and crushing with a ball mill, 0.7 g /
Dispersion B is obtained by dispersing in water at a concentration of.

(3) On the other hand, natural pulp fibers are formed into a dome shape by a conventionally known method to obtain a dome-shaped substrate.

(4) Using the dome-shaped substrate as a net-making machine, mixing and stirring the dispersions A and B while gradually adding each of the dispersions A and B, and sucking with a Nash pump to disperse the water in the substrate. Accumulate ingredients.

(5) The laminated body of the paper making machine and the deposited layer is left at room temperature for about 24 hours, and then placed in a drying oven at 105 ° C. for about 3 hours to evaporate water.

(6) Temperature of the dried laminate at 270-300 ℃, cylinder pressure
Press-mold with a pressure of 5 tons.

(7) The press-molded laminated body is put into a vacuum sintering furnace, heated, held at 1800 ° C. for about 90 minutes, gradually cooled, and then taken out from the sintering furnace.

(8) After sintering, the laminated body was washed in water to remove the carbonized substrate and air-dried, and then vibrated with silicon nitride 11 and silicon carbide whiskers 12 shown in FIGS. 1-a and 1-b. Board 1
Got

When the physical properties of the diaphragm thus obtained were measured, the results shown in the following table were obtained.

However, diaphragm: diaphragm of the present invention diaphragm: diaphragm of silicon nitride alone density: g / cm ³ , Young's modulus: × 10 ¹² dyn / cm ² , specific elastic modulus: × 1
0 ¹² dyn · cm / g that is, the vibration plate of this invention increase the Young's modulus as compared to the increase in density compared to the diaphragm of the prior art is very large, it is thereby allowed to rise to specific modulus This makes it possible to raise the maximum limit frequency of the speaker and thus contribute to the expansion of the reproduction frequency band.

The effects of the present invention are as follows.

Since the diaphragm of the present invention uses whiskers whose length in the lengthwise direction is larger than the diameter, most of the whiskers have a lengthwise direction with respect to the plane of the papermaking net due to the water flow during papermaking.
They are deposited in parallel directions, that is, they are oriented along the surface direction of the deposited layer formed on the mesh forming surface. The orientation of the vibrating plate is promoted by the pressing in the step (6), and the structure of the vibrating plate completed after sintering is such that whiskers existing in the ceramic are vibrating plate in the longitudinal direction as shown in FIG. 1-b. Since it is oriented in the direction along the plane of, it is particularly resistant to bending forces.

In addition, the Young's modulus of the whiskers is extremely high in synergistic with the above-mentioned structural action, which is also the cause.

In addition, one of the reasons is that a dense ceramic is formed by sintering.

Further, according to the present invention, the whiskers having a large Young's modulus are arranged in a matrix in the ceramic, so that there is no separation phenomenon between the whiskers and the whisker, and therefore the input withstand characteristics can be improved.

As described above, according to the present invention, the diaphragm and the whiskers, which are made of the sintered ceramic in which the lengthwise direction is oriented in the direction along the surface of the diaphragm and are made of sintered ceramics, are irradiated with ultrasonic waves and dispersed in water. A step of mixing a ceramic material and a sintering aid to disperse them in water, and a fiber-deposited layer formed into a vibration plate shape is used as a net, and the two dispersions are mixed and stirred to form a paper. A step of depositing whiskers and a ceramic material on the net, a step of hot-pressing the deposited layer of the nets and whiskers and ceramic, a step of heating the laminate obtained in the step and sintering the ceramic material, A method of manufacturing a vibration plate, which comprises a step of removing the carbonized papermaking network, and can provide a vibration plate having an extremely large Young's modulus with a relatively simple manufacturing facility. In which it is possible to obtain an excellent effect without the conventional example.

[Brief description of drawings]

FIG. 1-a is a sectional view of the diaphragm of the present invention, and FIG. 1-b is an enlarged sectional view of a portion A in FIG. 1-a. Reference numeral 1 is a diaphragm, 11 is a ceramic, and 12 is a whisker.

Claims (3)

[Claims] 1. A diaphragm of an audio device, comprising a sintered ceramic containing therein whiskers whose longitudinal direction is oriented along a surface of the diaphragm. 2. The diaphragm for an audio equipment according to claim 1, wherein the whiskers are silicon carbide whiskers and the sintered ceramics are silicon nitride. 3. A step of irradiating ultrasonic waves to disperse the whiskers in water, a step of mixing a ceramic material and a sintering aid to disperse the particles in water, and a fiber deposition layer formed into a vibration plate shape. And a step of depositing the two dispersions while mixing and diluting the mixture to deposit whiskers, a ceramic material and a sintering aid on the net, and a deposition layer of the net and whiskers and the ceramic material and the sintering aid Of a diaphragm of an audio device, which comprises a step of hot-pressing a laminated body made of, a step of heating the laminated body after pressing to sinter a ceramic material, and a step of removing the carbonized paper net. Production method.