JPH035720B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a diaphragm for an acoustic transducer, particularly to an improvement of a diaphragm using a heat-resistant synthetic resin. [Prior Art] To explain conventional diaphragms for acoustic transducers, for example, diaphragms for speakers, synthetic resins with a relatively high Young's modulus are used as diaphragms for speakers for medium and high frequencies. A diaphragm whose surface is laminated with metal or other synthetic resin has been considered as a base. The reason for adopting such a laminate structure is to combine the physical properties of the base and the laminate to pursue the physical properties required for a diaphragm, such as improving the rigidity of the diaphragm. [Problems to be solved by the invention] However, in conventional diaphragms like this,
Not only is it not possible to obtain desired characteristics, but the lamination means requires relatively expensive equipment such as vacuum deposition or sputtering, and requires long processing times, resulting in an increase in product costs. Also, as a laminate,
JP-A-56-109096 discloses that SiO ₂ is suitable. The publication describes SiO ₂ on a metal substrate.
A means for laminating ceramics such as the above by thermal spraying has been disclosed. However, the formation of a laminate by this thermal spraying method is limited to metals with high heat resistance as the substrate, and cannot be applied to synthetic resin substrates. or,
Since the laminate formed by thermal spraying contains voids, there are problems such as insufficient stiffness reinforcing effect. [Means for Solving the Problems] The present invention provides a diaphragm for an acoustic transducer, which has a heat-resistant synthetic resin as a base and has a dense SiO ₂ film formed from a silicon-alkoxyl compound formed on the surface of the base. Formed using a simple process
The rigidity of the base is reinforced with a SiO ₂ coating. [Example] A dome-shaped diaphragm substrate having a thickness of 20 μm is obtained by hot press molding a semi-cured aromatic polyimide resin film, and after sandblasting both surfaces to roughen the surface, the substrate is washed with trichlorene. Next, it is a type of alkoxide which is a compound of alkoxyl and silicon represented by (RO-),
52 g of tetraethoxylan (Si(OC ₂ H ₅ ) ₄ ) in which the aforementioned R is an ethyl group, which is a type of alkyl group;
_H2O for hydrolysis: 10.9ml, for pH adjustment
After preparing a mixed solution of 7.1 ml of HC1 and 50 ml of C ₂ H ₅ OH as a solvent (hereinafter referred to as an alcoholic solution of tetraethoxylan), the tetraethoxylan was left to stand for 24 hours, causing slight gelation and viscosity. The substrate was immersed in the alcohol solution of Ran, pulled up, the excess solution was dropped and removed, and the base was held horizontally by supporting the flange part and left at room temperature for about 96 hours. The solution was allowed to gel. Next, in the air from room temperature to about 20
The temperature is increased to 350℃ at a rate of ℃/hr, and at that temperature approximately
Heating was maintained for 15 hours. After that, the temperature is lowered to room temperature at a rate of about 45℃/hr,
A 5 μm thick SiO ₂ film was formed on both sides of the substrate. The form of the SiO ₂ coating using the alcohol solution of tetraethoxylan is performed according to the following chemical formula. nSi(OC ₂ H ₅ ) ₄ +4H ₂ O →nSi(OH) ₄ +4nC ₂ H ₅ OH nSi(OH) ₄ →nSiO ₂ +2nH ₂ O Also, it has a methyl group CH ₃ instead of the ethyl group C ₂ H ₅ A similar reaction occurred with tetramethoxylan, forming a SiO ₂ film. [Effects of the Invention] The physical properties of the diaphragm obtained in the above example and the untreated diaphragm are shown in the following table.

[Table] As described above, the diaphragm obtained according to the present invention was able to obtain good characteristics as a diaphragm due to the SiO ₂ film covering the surface of the heat-resistant synthetic resin. Further, when the diaphragm of the embodiment of the present invention and the untreated diaphragm were assembled into a speaker and the frequency characteristics were measured, the results shown in FIG. 1 were obtained. As is clear from the frequency characteristics, in the speaker equipped with the diaphragm of the present invention, the upper limit frequency increased and the reproduction band could be expanded. In addition, this invention combines silicon and alkoxyl (RO
Since the SiO ₂ coating is formed by a simple process of gelling and heating the compound with (-), it is possible to form a relatively thick and dense coating, which has the advantage of being extremely suitable for mass production.

[Brief explanation of drawings]

FIG. 1 shows the frequency characteristics of a speaker incorporating an embodiment of the present invention and an untreated diaphragm.

Claims (1)

[Claims] 1. A diaphragm for an acoustic transducer, characterized in that the substrate is made of a heat-resistant synthetic resin, and a film of SiO ₂ produced from a silicon-alkoxyl compound is formed on the surface thereof.