JPH045316B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing acoustic diaphragms for microphones, headphones, speakers, etc.

BACKGROUND TECHNOLOGY AND PROBLEMS In acoustic diaphragms for microphones, headphones, speakers, etc., edges must be flexible and other parts must be rigid. Various known methods have been used to form such acoustic diaphragms, but all of them have the disadvantage that they are not suitable for mass production or that the characteristics of the products are not constant.

In the lamination method, which is one of such known methods, another film, such as a polyethylene terephthalate film, is laminated only on the vibrating surface of the vibrating plate. This method requires the preparation of another film coated with adhesive, and the complicated process of cutting the film to a predetermined size and attaching it to a predetermined location, making it unsuitable for mass production. . In the resin coating method, which is another known method, resin is applied only to the vibration surface of the diaphragm and cured to increase rigidity, but the application is done by brushing, dripping, spraying, etc. First, it is difficult to uniformly apply resin only to the vibrating surface, and uneven coating tends to occur.
Therefore, there is a possibility that the characteristics of the product may vary. Furthermore, in the single layer molding method, which is another Kochi method, single layer molding is performed so that the thickness of the vibration surface of the diaphragm is thick and the thickness of the edge portion is thin. but,
In this method, the thickness of the vibrating surface and the edge portion must be determined extremely precisely, making it difficult to mass-produce uniform, custom-made products.

In order to eliminate such drawbacks, the inventors of the present invention have developed
proposed an acoustic diaphragm consisting of a base film and a resin layer made of a radiation- or ultraviolet-curable resin, the vibration surface of which is hardened by radiation or ultraviolet irradiation to increase its rigidity, and a method for manufacturing the same. . However, in this case, the resin layer is left uncured at the edges, but the acoustic sensitivity decreases as the coating thickness increases in the high frequency range. A new problem arises.

Purpose of the Invention In view of the above points, the present invention provides a method for manufacturing an acoustic diaphragm that is suitable for mass production, has constant product characteristics, and has good sensitivity even in the high frequency range of the obtained acoustic diaphragm. It is something to do.

Summary of the Invention The present invention provides a method for manufacturing an acoustic diaphragm having a vibration surface and an edge portion, in which a coating layer is formed by substantially uniformly coating a radiation or ultraviolet curable resin on a base film, and then the The base film on which the coating layer has been formed is molded into a predetermined diaphragm shape, and the curable resin applied to the diaphragm surface is cured by irradiating radiation or ultraviolet rays onto the vibration surface of the molded body formed into the diaphragm shape. By doing so, a hardened portion corresponding to the vibration surface and an unhardened portion corresponding to the edge portion of the molded body are formed in the applied layer, and then the unhardened portion of the applied layer is removed. The present invention relates to a method of manufacturing an acoustic diaphragm, characterized in that:

EXAMPLE A method for manufacturing an acoustic diaphragm according to the present invention will be described with reference to the drawings.

First, as shown in FIG.
Next, a resin 2 that is cured by radiation or ultraviolet light is formed by an appropriate method. Next, as shown in FIG. 2, this base film 1 is molded into a well-known predetermined diaphragm shape using a molding machine, and a ring 3 is glued to a portion corresponding to the outer periphery of the edge portion of the acoustic diaphragm. let Subsequently, as shown in FIG. 3A, the base film is cut and separated into a large number of diaphragms, and a mask 4 is formed on the edge portions of a suitable material so that these portions are irradiated with radiation, ultraviolet rays, etc. Prevent it from hardening. The molded body 10 on which the mask has been formed is irradiated with radiation, ultraviolet rays, etc. by an appropriate means to harden its vibrating surface to an appropriate degree, and the mask 4 is removed. As a result, the molded body 10 has
As shown in FIG. 3B, while the cured resin layer 5 is formed, the resin layer 2 remains uncured at the edge portion where the mask is formed. When this resin layer 2 is removed by an appropriate means, for example, with a solvent, a hardened resin layer 5 is formed on the molded body 10 only in the portion corresponding to the vibration surface, as shown in FIG. 3C, and the rigidity is increased. will be performed.

FIG. 4 shows an example of a method of irradiating with radiation or ultraviolet rays. In FIG. 4, a large number of molded bodies 10 forming masks are arranged on a plate 11, and this plate 11 is placed on a belt conveyor 12 rotating at a predetermined speed. These molded bodies 10 are exposed to radiation or ultraviolet irradiation equipment 13
It is irradiated with radiation or ultraviolet rays as it passes below.

In this invention, the material that can be used as the base film is not particularly limited as long as it has been conventionally used for acoustic diaphragms, but polyethylene terephthalate is particularly preferred.

Any conventional method can be used to apply the resin onto the base film, and examples thereof include a spraying method, a brush coating method, a gravure roll method, and a doctor blade method.

The base film coated with resin is molded into a well-known predetermined shape using a molding machine as described above, but the molding method applied in this case is not limited to any particular method. For example, a suitable molding method such as a pressure molding method may be used. Further, shaping into a predetermined shape can be carried out by either a continuous method or a batch method.

The resin that can be used in this invention may be any resin that can be cured when irradiated with radiation and/or ultraviolet rays and impart desired rigidity to the vibrating surface, and is not limited to any specific resin. It's not a thing. As such a resin, it is preferable to use, for example, a monomer or oligomer having an acrylic or methacrylic double bond. Among such monomers, those having an acrylate double bond include, for example, vinylpyrrolidone, 2-ethylhexyl acrylate, lauryl acrylate, hydroxyethyl acrylate, ethoxyethoxy acrylate, tetrahydrofurfuryl acrylate, Aronix M-5700.
Monofunctional monomers such as (trade name), diethylene glycol diacrylate, tetraethylene glycol diacrylate, neopentyl glycol diacrylate, Aronix M-6100 (trade name)
and polyfunctional monomers such as trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, dipentaerythritol hexaacrylate, and dipentaerythritol pentaacrylate. Examples of such monomers having a methacrylic double bond include those in which the acrylic double bond of the above-mentioned monomer is replaced by a methacrylic double bond. Further, examples of the resin species that form the skeleton having such double bonds include alkyd resins, polyesters, acrylic resins, polyurethanes, and epoxy resins. When an oligomer is used as the resin, it may be converted into an oligomer using a conventional method using the monomers described above.

It is preferable to use the above-mentioned resin together with a photosensitizer, and upon irradiation with light, the sensitizer decomposes to generate radicals, which polymerize and crosslink through the radicals. Such sensitizers include, for example,
Examples include benzoin compounds and benzophenone-amine mixtures. Examples of benzoin compounds include benzoin alkyl ethers, and examples of the alkyl group include methyl, isopropyl, n-butyl, and t-butyl.
Examples of amine compounds used in the benzophenone-amine mixture include methyldiethanolamine, triethanolamine, N-methylmorpholine, triethylamine, dibutylamine,
Examples include N,N-dimethylbenzylamine and N,N-dimethylaniline.

As mentioned above, the uncured portion of the resin layer 2 is removed by using a solvent, for example.
As this solvent, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. are used.

The molded body obtained as described above may be cut and separated into a large number of molded body pieces constituting each diaphragm, or it may remain continuous without being cut and separated.
A predetermined portion, that is, an edge portion, is made of aluminum,
The resin is masked with a mask, and then exposed to radiation or ultraviolet rays to harden the exposed resin parts and give them a certain level of rigidity. As the radiation, electron beams, gamma rays, etc. are used. Furthermore, the amount of radiation, ultraviolet rays, etc. to be irradiated is not particularly limited, and may be appropriately selected in consideration of the type of resin, curing speed, etc.

The present invention will be explained below using specific examples.

Specific example 1 A polyethylene terephthalate film with a thickness of 9μ is used as a base film, and on this base film, a polyfunctional acrylate monomer (trade name "DPHA", manufactured by Nippon Kayaku Kogyo Co., Ltd.) and a filler to prevent flow are placed. A laminated film was prepared by applying the mixture to a film thickness of 40 μm using a doctor blade method.

Next, this laminated film was pressure-molded to form a dome-shaped diaphragm for a dynamic microphone. Mask the edge of this diaphragm with aluminum, distance 20cm, strength 80W/cm,
The dome portion was cured by irradiating ultraviolet light at a feed rate of 10 cm/min. Next, this diaphragm was immersed in methyl ethyl ketone to remove the resin at the edges and dried to obtain a desired diaphragm.

The results of measuring the output frequency characteristics of a dynamic microphone using this diaphragm are shown in broken lines in FIG.

As a comparative example, the output frequency characteristics of a dynamic microphone using a diaphragm made only of 9μ polyethylene terephthalate film were measured in the same manner, and the output frequency characteristics are shown by the solid line in FIG.

In FIG. 5, compared to the comparative example, the microphone using the diaphragm according to the present invention has
The high range from 5000 to 20000Hz is lifted, the flat part extends to the high range, and the sensitivity around 500 to 10000Hz is also comparable. The listening results showed that the high range was extended,
The low range was tight, the midrange had good tension, and overall sound localization was good.

Specific example 2 A polyethylene terephthalate film with a thickness of 12μ is used as a base film, and a polyfunctional acrylate monomer (trade name "Aronix", manufactured by Toagosei Chemical Industry Co., Ltd.) is filled on this base film to prevent flow. A laminated film was prepared by applying the mixture with the material to a film thickness of 50 μm using a doctor blade method.

Next, using this laminated film, a dome-shaped diaphragm of a tweeter for a two-way speaker system was formed by integrally compressing the dome portion and the edge portion that constitute the vibration surface. Mask the edge of this diaphragm with aluminum and
The dome was cured by irradiating it with ultraviolet light at an intensity of 80 W/cm and a feed rate of 10 cm/min. Next, this diaphragm was immersed in methyl ethyl ketone to remove the resin at the edges and dried to obtain a desired diaphragm.

The results of measuring the sound pressure frequency characteristics of a two-way speaker system using this diaphragm are shown in the sixth section.
Indicated by dashed lines in the figure.

Further, as a comparative example, the sound pressure frequency characteristic measured in the same manner for a two-way speaker system using a diaphragm made only of a 12 μm thick polyethylene terephthalate film is shown by a solid line in FIG.

Also in FIG. 6, the two-way speaker system using the diaphragm according to the present invention has a longer high range than the comparative example, and this is especially true.
It is noticeable around 20000Hz. Also, the listening results showed that the stability in the high range was increased and the extension was good.

Effects of the Invention The advantages achieved by the present invention are as follows. Firstly, in conventional double molded films, when molding the base film, another film coated with adhesive was positioned and pasted together, which required a time-consuming and complicated process. The present invention does not require this, and has the great advantage of being able to be efficiently mass-produced on a production line.

Second, by controlling the amount of radiation or ultraviolet radiation, the vibration surface can be easily improved and controlled.

Thirdly, since the uncured portion of the resin coating layer is removed, the overall weight of the acoustic diaphragm is reduced, and a decrease in sensitivity can be effectively prevented, especially when the resin coating layer is thick. Therefore, it is possible to provide speakers, headphones, microphones, etc. that have particularly good high-frequency characteristics.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the structure of the material of the acoustic diaphragm used in this invention, Fig. 2 is a sectional view showing the molded state, Fig. 3A is a sectional view showing the state with a mask on, and Fig. 3B. 3C is a sectional view showing the state after the resin has been cured, FIG. 3C is a sectional view showing the state after removing the uncured resin, FIG. 4 is a perspective view showing the state of irradiation with radiation or ultraviolet rays, and FIG. FIG. 6 is a curve diagram showing the output frequency characteristics of a dynamic type microphone for explaining the present invention, and FIG. 6 is a curve diagram showing the sound pressure frequency characteristics of a two-way speaker system for explaining the present invention. In addition, in the symbols used in the drawings, 1...
... Base film, 2 ... Resin layer, 4 ... Mask, 5 ... Cured resin layer, 10 ... Molded object, 1
3...Irradiation device.

Claims (1)

[Claims] 1. In a method for manufacturing an acoustic diaphragm having a vibration surface and an edge portion, after forming a coating layer by almost uniformly coating a radiation or ultraviolet curable resin on a base film, The base film on which the coating layer has been formed is molded into a predetermined diaphragm shape, and the curable resin applied to the diaphragm surface is cured by irradiating radiation or ultraviolet rays onto the vibration surface of the molded body formed into the diaphragm shape. By doing so, a hardened portion corresponding to the vibration surface and an unhardened portion corresponding to the edge portion of the molded body are formed in the applied layer, and then the unhardened portion of the applied layer is removed. A method of manufacturing an acoustic diaphragm, characterized in that: