JPS6033040B2 - Manufacturing method of diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a diaphragm used in audio equipment such as speakers and microphones, and in particular, a method for manufacturing a diaphragm for use in audio equipment such as speakers and microphones, in which a diffusive substance with a high specific elastic modulus is diffused on the surface and an appropriate uneven pattern is formed to improve bending rigidity. The present invention relates to a method of manufacturing a diaphragm having a structure formed therein.

Generally, it is well known that increasing the bending stiffness of a diaphragm eliminates deformation that occurs when the diaphragm is vibrated, and improves strain characteristics.

In order to increase the bending stiffness of the diaphragm, it is sufficient to increase the thickness of the diaphragm, but increasing the thickness of the diaphragm increases the mass and reduces sensitivity.

Other methods for increasing the bending stiffness of the diaphragm include a method of inserting corrugations and a method of providing unevenness on the surface of the diaphragm.

Inserting corrugations increases the bending strength of the swing plate in the circumferential direction, making it possible to prevent vibrations that cause deformation in the circumferential direction, such as hanging bell vibrations. Furthermore, by making the surface uneven, it is possible to increase the bending stiffness in the circumferential direction and the longitudinal direction, and the strain characteristics can be significantly improved. Another method to increase the bending stiffness of the diaphragm is to increase the specific elastic modulus (E/
A method of constructing a diaphragm using a material with a large p:E=Young's modulus, p=diaphragm density is well known.

Beryllium and boron are materials with a high specific modulus of elasticity, but both materials have poor workability. Boron in particular cannot be processed at all by pressing, etc., and it is difficult to form it into a diaphragm by vapor deposition. Not only does this require the use of low-productivity methods, which increases processing costs, but the shape of the diaphragm is also severely restricted, resulting in a lack of freedom, and in the end, it is not possible to fully utilize the excellent characteristics of the material. could not. Of course, when the diaphragm is made of these materials, it is even more difficult to provide the diaphragm with corrugations or irregularities in an appropriate pattern. An object of the present invention is to provide a method for manufacturing a diaphragm having a large specific modulus of elasticity and having corrugations and irregularities having an appropriate pattern. In other words, the diaphragm base is made of a material with good moldability and a relatively large specific modulus of elasticity, such as titanium, and the material, which is different from the material of the diaphragm base, diffuses into the diaphragm base to improve the ratio of the diaphragm base. Diffusive substances that can increase the elastic modulus,
For example, in a manufacturing process in which boron is diffused into the diaphragm substrate to increase its specific elastic modulus, a diffusion prevention film is formed in a predetermined pattern on one side of the surface of the diaphragm substrate to reduce the amount of diffusion of the diffusing substance. The present invention provides a method for manufacturing a diaphragm in which a desired uneven pattern is provided on a diaphragm substrate by varying the amount of diffusion on both sides. The present invention will be explained in detail below with reference to the drawings.

First, as shown in Fig. 1, a thin titanium plate is formed into a desired diaphragm shape by press processing or other methods, and one side of the surface (the inside of the diaphragm base 1 in the figure) is coated with lacquer, enamel, ink, etc. The diffusion prevention film 2 is provided in a predetermined corrugation-shaped pattern by means such as printing or coating. Next, as shown in FIG. 2, this diaphragm substrate is placed in a container 3 made of a heat-resistant material such as alumina, carbon, etc. together with a mixed powder of boron powder 4 as a diffusion substance and an alkali metal such as potassium 5. 1, put the lid 6 on, and heat it in the heating furnace (
(not shown) and heated in a temperature range of 90,000 to 1,300 pm. At this time, it is desirable to maintain a vacuum level of about 10-2 Torr in the heating furnace. Also, the heating time is 1 minute ~
Approximately 30 minutes is appropriate; if the heating temperature is high, the heating time should be short; if the heating temperature is low, the heating time should be long.
Due to heating, boron as a diffusion substance is diffused from the surface of the diaphragm base 1, and Ti is deposited on the surface of the diaphragm base 1 made of titanium.
A compound layer of B2, TiB, etc. is formed. The Young's modulus of Ti& is 54,000k9/fence, and the Young's modulus of titanium is 110.
Since it is about 5 degrees larger than that of 00k9/fence, the specific elastic modulus of the diaphragm base is greatly improved. FIG. 3 is an enlarged cross-sectional view of the diaphragm near the part where the diffusion prevention film 2 was provided in the corrugation pattern. Since the diffusion prevention film 2 of a predetermined pattern was provided on the side shown by arrow 7 in FIG. However, the amount of boron diffused is reduced, and the diaphragm base 1 expands due to the diffusion of boron, so it stretches and curves from the arrow 7 side, creating corrugations as shown in FIG. 3. By changing the pattern of the diffusion prevention film 2, it is also possible to create an appropriate pattern of protrusions and recesses such as hexagons and circles. As the diffusion material, silicon may be used instead of boron, but the performance will be somewhat worse than when boron is used. In the above explanation, we have described the method of embedding the diaphragm substrate in a mixture of poron powder and an alkali metal and performing diffusion treatment. A similar effect can be obtained by processing.

Alternatively, a diffusing substance such as boron powder may be applied to the surface of the diaphragm base and heated in an alkali metal gas to diffuse the diffusing substance, but in this case, the diaphragm base tends to deform. , measures to prevent deformation are required. The present invention is characterized in that a film that prevents the diffusion of a diffusing substance is provided on the diaphragm substrate, and unevenness is provided to vary the amount of diffusion on the front and back sides of the diaphragm substrate. It is also conceivable to apply a diffusion substance to the entire surface on one side, apply the diffusion substance in a desired corrugation or uneven pattern to the other side, and then process the mixture in an alkali metal gas.

However, when applying powder such as boron or silicon, which is a diffusing substance, to the diaphragm substrate, if it is mixed with an organic binder such as lacquer or enamel, the inventors' experiments showed that the binder was removed by heating for the diffusion process. This resulted in decomposition, discoloration of the surface of the diaphragm base, and a decrease in the amount of diffusion, resulting in a diaphragm that was unusable. To do this, it is necessary to mix it with a volatile solvent such as acetone before applying it, but in this case, all the solvent evaporates after application and only a layer of the diffusing substance remains, so it can be diffused just by touching it with your hand. The material peels off, making it difficult to create precise patterns. Of course, it is not possible to apply a diffusion substance in a predetermined pattern to a thin plate before it is formed into a diaphragm base, and then press it later to form it into a diaphragm base. Due to these drawbacks, it is impractical to form unevenness by applying a diffusion material in a predetermined pattern. In the method of the present invention, a diffusion prevention film with a predetermined pattern is provided using lacquer, enamel, ink, etc., so that the film adheres well to the diaphragm base and does not peel off even after processing such as pressing. When the plate base is a thin plate, it is also possible to print a diffusion prevention film in a predetermined pattern and then mold it into the diaphragm base using a press later.

Furthermore, even if lacquer, enamel, etc. are used, the substrate will not change color, unlike when mixed with a diffusive substance and applied. As described above, according to the method of the present invention, a diaphragm with a precise pattern of unevenness can be easily manufactured, and the specific modulus of elasticity of the diaphragm material is also improved, so a diaphragm with large bending resistance can be obtained. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the diaphragm substrate before the diffusion treatment in the present invention, and FIG. 2 is a cross-sectional view showing the diffusion treatment state in the present invention.
FIG. 3 is an enlarged sectional view of an uneven portion of a diaphragm manufactured according to the present invention. DESCRIPTION OF SYMBOLS 1... Vibration plate base, 2... Diffusion prevention film, 4... Diffusion substance. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A method for manufacturing a diaphragm in which a diffusing substance having a specific elastic modulus higher than that of the material of the diaphragm base is diffused from the surface of the diaphragm base, in which diffusion is prevented by a predetermined pattern on one side of the diaphragm base. A method for manufacturing a diaphragm, comprising forming a film and then diffusing the diffusion substance to vary the amount of diffusion on both sides of the diaphragm base in the film-forming portion, thereby providing a desired pattern of unevenness on the diaphragm base. 2. The method of manufacturing a diaphragm according to claim 1, wherein the diaphragm substrate on which the diffusion prevention film is formed is embedded in a diffusive material powder and heated and diffused.