JPS6128280B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a dome-shaped diaphragm.
In particular, the present invention relates to a method of manufacturing a dome-shaped diaphragm for an electroacoustic transducer, such as a diaphragm for a dynamic microphone.

[Summary of the invention]

The present invention provides a method for manufacturing a dome-shaped diaphragm in which a dome part of a vibrating main part and an edge part of a peripheral support part are integrally formed. By pouring the diaphragm material melted with a solvent into the recess and forming the resulting film into a dome shape by dissipating and volatilizing the solvent, manufacturing is easy and flexibility in selecting film thickness and diaphragm material is achieved. The purpose is to manufacture diaphragms with high height, high rigidity, and high compliance.

[Conventional technology]

For example, a diaphragm used in a small electroacoustic transducer such as a dynamic microphone has a vibrating main part (the so-called dome part) and a peripheral support part (the so-called edge part) integrally formed of the same material. Therefore, it is desired that a material for such a diaphragm satisfy various conditions such as airtightness, internal loss, strength, and moldability, and also be capable of realizing a compact high-compliance edge.

Here, FIG. 1 is a cross-sectional view showing an example of a conventional diaphragm 1 for an electroacoustic transducer. For example, a plastic film such as polyester is molded by air-pressure thermoforming or the like, and a dome portion, which is the main part of the vibration, is formed. 2 and an edge portion 3 which is a peripheral support portion are integrally formed.

In such a conventional diaphragm 1, if the thickness of the diaphragm 1 itself is increased to increase its rigidity in order to prevent unnecessary deformation even when a large sound pressure is applied, for example, the edge of the supporting part The compliance of the section 3 decreases, the lowest resonance frequency ₀ increases, and the low frequency characteristics deteriorate.

For this reason, conventionally, as shown in FIG. 2, a laminate film 4 as a separate member is adhesively fixed to the dome part 2, which is the main vibration part of the diaphragm 1', to increase the rigidity of the dome part 2. In addition, by leaving the edge portion 3, which is the peripheral support portion, as a thin film, high compliance and good characteristics with the above-mentioned low ₀ can be obtained. Such adhesion of the laminate film 4 may extend to an area slightly protruding from the outer periphery of the dome portion 2, as shown in FIG. Since the diaphragm 1'' is left as it is, a high compliance diaphragm 1'' can be obtained.

[Problem that the invention seeks to solve]

However, in small electroacoustic transducers such as dynamic microphones, the dome-shaped diaphragm itself is small and thin, so it is difficult to attach the laminate film 4 during manufacturing, and the adhesive Due to variations in the thickness of the adhesive and the effects of the physical properties of the adhesive itself, problems such as variations in the properties of the diaphragm as a product or failure to obtain the desired properties arise. There is.

The present invention has been made to eliminate these conventional drawbacks, and has a vibrating main body with high rigidity.
This is a method of manufacturing a dome-shaped diaphragm with high compliance of the peripheral support part, which improves transducer performance at large inputs, has less variation in characteristics and sound quality, and has high manufacturing efficiency. The purpose is to provide a manufacturing method.

[Means for solving problems]

The present invention provides a method for manufacturing a dome-shaped diaphragm in which a dome part of a vibrating main part and an edge part of a peripheral support part are integrally formed. The diaphragm material is melted with a solvent and poured into this recess.
The solvent in this poured solution is diffused and volatilized to obtain a film that is thick at the center and thin at the periphery, and this film is formed into a dome shape, with the thick center becoming the dome that is the main vibration body and the periphery being thin. It is characterized by having an edge part.

[Effect]

By using the casting method, there is not only a high degree of freedom in selecting the thickness of the diaphragm film and the diaphragm material, but also a diaphragm with high rigidity and high compliance can be manufactured easily and with good mass productivity. .

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described.
This will be explained with reference to the drawings.

First, as a first embodiment of the present invention, plastic such as polyester, styrene, polycarbonate, etc., which will be the material of the diaphragm, is dissolved in a solvent such as toluene in the form of a fine powder, and this solution is casted as shown in FIG. Recess 11 of jig 10
Pour into. The recessed portion 11 of this casting jig 10 is deep at the central portion where the vibration main body is formed, and shallow at the peripheral portion where the peripheral support portion is formed.
The diaphragm film 13 has a stepped structure and is formed by dissipating and volatilizing the solvent of the solution 12 poured into the recess 11. As shown in FIG. It's getting thicker.

In such a casting method, a film with a thickness of, for example, about 8 to 9 μm can be formed, and the optimum thickness can be determined by taking into account the rigidity of the vibrating main part 14 of the diaphragm, the compliance of the peripheral support part 15, etc. can be selected.

Next, the sheet-shaped diaphragm film 13 formed as described above, each having a different thickness at each part, is placed on a molding die 16, for example, as shown in FIG. 6, and is heated from above in the figure. By blowing air (see the arrow in FIG. 6), the diaphragm 17 is shaped into a desired shape, such as a dome-shaped vibrating main body 14 as shown in FIG.
form. Here, a protrusion 18 is formed at the center of the molding die 16 shown in FIG. 6, and guides a recess or hole (not shown) formed at the center of the sheet-like diaphragm film 13. By doing so, the center of the diaphragm film 13 can be determined. In addition, a through hole 19 is formed at a predetermined position of the mold 16, and penetrates from the front surface (upper surface in the figure) to the back surface (lower surface in the figure), and the diaphragm film 13 is formed during compressed air thermoforming as described above. This prevents the diaphragm from deforming due to local accumulation of air in the air layer between it and the mold 16.

The diaphragm 17 of FIG. 7 formed in this way
is used in an electroacoustic transducer 26 as shown in FIG. That is, in FIG. 8, a voice coil 20 is placed in a gap 25 in a magnetic circuit consisting of a magnet 21, a yoke 22, a center pole 23, and a plate 24.
is connected to the diaphragm 17 via a coil bobbin or the like.

As is clear from the above description, the diaphragm film 13 itself before being molded is formed by the casting method so that the vibration main body part 14 is moved to the peripheral support part 1.
5, and by simply processing this diaphragm film 13 using a method such as compressed air thermoforming, high rigidity can be obtained extremely easily without the hassle of conventional laminating methods. In addition, a diaphragm 17 with high compliance can be obtained. Moreover, since the casting method is used, various compositions of the diaphragm are possible.For example, as in the second embodiment shown in FIG.
A first material solution 12a is poured into the lower part of the recess 11, and then a second material solution 12b is poured onto the first material solution 12a to obtain a two-layered diaphragm film. be able to. The subsequent manufacturing and assembly steps are the same as those in the first embodiment described above, so the explanation will be omitted. In addition, various properties such as rigidity can be easily changed by adding fine metal powder to the plastic solution and stirring and mixing.

Furthermore, it is possible to arbitrarily change the thickness of each part of the diaphragm. For example, as in the diaphragm 30 of the third embodiment shown in FIG.
1 to a part of the peripheral support part 32, and only the outer edge part of the peripheral support part 32 is made thin,
Or like the fourth embodiment shown in FIG.
The vibration main part 34 of the diaphragm 33 may be made thickest, and the peripheral support part 35 may be thinner than this, but have a thickness of three steps as a whole, with the inner edge being thicker and the outer edge being thinner.

In this way, any required thickness can be given to the peripheral support part 35, which is the edge part, and by making the edge part thinner, the area of the edge part can be reduced, so that the influence of the edge on the characteristics is reduced. This has great practical advantages. Generally, the thickness of the film is determined by the manufacturer's standard.
The fact is that it is not possible to easily change the thickness of the film, so the thickness must be selected to improve performance by finding the best points based on the diameter, shape, etc. of the diaphragm.

〔Effect of the invention〕

According to the method for manufacturing a dome-shaped diaphragm of the present invention,
By using the casting method, the thickness of the diaphragm film can be arbitrarily selected, and the diaphragm material can be freely selected. In addition, a highly rigid and high compliance diaphragm that is thick in the center and thin in the periphery can be easily obtained with good mass production. Furthermore, a diaphragm with a two-layer structure can be easily manufactured.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing examples of conventional diaphragms different from each other. 4 to 7 show cross-sectional views along the manufacturing process of the first embodiment of the present invention, FIG. 4 is a cross-sectional view of a casting jig, FIG. 5 is a cross-sectional view of a diaphragm film, FIG. 6 is a sectional view of the molding die, FIG. 7 is a sectional view of the molded diaphragm, and FIG. 8 shows an example of an electroacoustic transducer constructed using the diaphragm of this embodiment. FIG. FIG. 9 is a sectional view of a casting jig for explaining a second embodiment of the present invention. FIG. 10 is a sectional view of a diaphragm as a third embodiment of the invention, and FIG. 11 is a sectional view of a diaphragm as a fourth embodiment. 10... Casting jig, 11... Recessed part,
13... diaphragm film, 14, 31, 34...
Vibrating main body part, 15, 32, 35... peripheral support part,
16... Molding die, 17, 30, 33... Vibration plate.

Claims (1)

[Scope of Claims] 1. A recess is provided on the upper surface of the casting jig, and the center part is deep and the peripheral part is shallow. A diaphragm material is melted with a solvent and poured into the recess, and the solvent of the poured solution is diffused. The film was volatilized to obtain a film that was thick at the center and thin at the periphery, and this film was formed into a dome shape so that the thick center became the dome, which was the main part of the vibration, and the periphery became the thin edge. A manufacturing method for a characteristic dome-shaped diaphragm.