JPS6224800A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To attain low cost and to obtain flat high frequency characteristics while improving waterproofness and processability by providing a nitrocellulose resin layer to a diaphragm base formed by using natural fibers as major components and providing a vinyl resin layer on the surface. CONSTITUTION:The nitrocellulose resin layer 1b is formed on the diaphragm base 1a using only natural fibers or natural fibers as major components and the vinyl resin layer 1c is provided on the surface. The diaphragm base 1a is formed by using cone paper paper-making, e.g., natural fibers and mixing synthetic fibers to the natural fiber as the major components. As the nitrocellulose resin layer 1b, a lacquer resin having good waterproofness, water repellency and processability is used, for example. The vinyl resin layer 1c formed on the surface of the nitrocellulose resin layer 1b has high waterproofness and proper flexibility of film giving effect on the loss of the diaphragm. Thus, regardless of the provision of waterproofness and water repellency, flat sound pressure frequency characteristics are shown and the diaphragm with excellent surface glitter is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diaphragm that radiates sound for a speaker that converts electrical audio signal current into mechanical vibration to produce sound.

[Conventional technology]

Generally, the physical properties required for a speaker diaphragm are as follows:
In order to improve the output sound pressure frequency characteristics of the speaker, the speaker must be lightweight, have a high Young's modulus, have a low density, and have an appropriate internal loss.

In other words, the higher the Young's modulus and the lower the density, the higher the resonant frequency of the diaphragm becomes, and the piston motion area is expanded, so the frequency band of the speaker becomes wider, and the larger the internal loss, the more the split resonance of the diaphragm becomes. decreases and the frequency characteristics become flat.

From this point of view, as a diaphragm that satisfies the above-mentioned required physical properties, diaphragms formed by paper-making of beaten natural fibers, chemical fibers, or fiber materials that are a mixture of these have conventionally been proposed. Widely manufactured.

Since such a diaphragm is manufactured by paper-making, it is susceptible to water and humidity, and swelling and performance deterioration occur due to absorption of water.

However, recently, the usage of speakers has expanded to include outdoor use and car door mounts, and the number of speakers that come into contact with water and moisture has increased, so the diaphragm itself is required to have water return properties and water resistance. It has come to be.

Conventional methods for increasing the water resistance of the diaphragm itself include (a) impregnating natural fibers with a thermosetting resin such as phenol resin or epoxy resin; (c) using a plastic sheet made of polypropylene, polyethylene, terephthalate, etc. Methods include using simple metals such as aluminum and titanium, coating the surface of the natural fiber diaphragm substrate with a synthetic resin, and heat-adsorbing a thermoplastic film such as nylon onto the surface of the natural fiber diaphragm substrate. It was used.

However, the item in item a has a low internal loss tan δ,
Since the density ρ is high, in order to make the diaphragm lightweight, the thickness of the diaphragm must be thinned, which has the drawback of causing peaks and dips in the frequency characteristics.

Also, although the items mentioned above have excellent waterproof properties,
It has the disadvantage that it is easily deformed in a high temperature atmosphere of about 100° C. and is expensive.

In addition, the above-mentioned 0-term material has a large Young's modulus E, but has a small internal loss tan δ, so it is difficult to control high-frequency resonance, and there is a limit to the elongation of the material, resulting in poor workability. The disadvantage is that it is very expensive.

In addition, in the case of item d above, when the synthetic resin is applied, the synthetic resin penetrates into the diaphragm base material, so if the synthetic resin is applied until sufficient waterproofness is achieved, the Young's modulus E becomes small.
This has the disadvantage that the output level in the high range of the sound pressure frequency characteristic decreases, resulting in poor efficiency.

Furthermore, in the case of item 0, since the thin film is heated and adsorbed onto the surface of the natural fiber diaphragm base material, pinholes occur and it is not possible to provide complete waterproofness, especially when the original cone-shaped vibration It is unsuitable for use as a board, and if a thick film is used, the speaker sensitivity will be reduced.

[Purpose of the invention]

The present invention is intended to eliminate the above-mentioned drawbacks of the conventional waterproof speaker vibration plate.It eliminates pinholes, provides complete waterproofness, has good workability, and is inexpensive. An object of the present invention is to provide a diaphragm for a speaker that can obtain flat high frequency characteristics, which is an advantage of a diaphragm mainly composed of natural fibers.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention forms a nitrocellulose resin layer on a diaphragm base material made only of natural fibers or mainly composed of natural fibers, and a vinyl resin layer is provided on the surface of the nitrocellulose resin layer. The gist of this is that

(Example of the invention) The present invention will be explained in more detail with reference to FIGS. 1 and 2.

Reference numeral 1a denotes a diaphragm base material, which is formed by, for example, cone paper made from natural fibers, or by blending synthetic fibers with natural fibers as a main component.

1b is a nitrocellulose-based resin layer formed on the diaphragm base material 1a, and for example, a lacquer-based resin is used, which has good waterproof properties, water-repellent properties, and good workability.

Reference numeral 1c denotes a vinyl resin layer formed on the surface of the nitrocellulose resin layer 1b. This vinyl resin has high waterproofness and a suitable flexibility of the coating that affects the loss resistance of the diaphragm.

To manufacture such a diaphragm 1, first, as a first step, a diaphragm base material 1a made of natural fibers is impregnated or coated with a lacquer-based resin, and the lacquer-based resin is applied to both sides of the diaphragm base material 1a. Form layer 1b.

Next, as a second step, a vinyl resin File is formed by painting or coating the surface of the lacquer resin layer 1b with a vinyl resin.

For this painting or coating, a lacquer resin layer 1
Water-soluble emulsion type vinyl resin is suitable because b has high draftability suitable for painting and coating with water-soluble resin, and after painting and coating, water-soluble emulsion type vinyl resin is used for diaphragm. It forms a uniform coating film on the surface without penetrating 1a.

Next, one embodiment of the present invention and its manufacturing method will be described.

Paper making and molding of UKP20″SR pulp fibers to a thickness of Q
, 5** Take a cone-shaped diaphragm base material 1a, impregnate it with a 10% by weight nitrocellulose-based clear lacquer solution for 1 to 3 minutes, dry it with hot air at about 80°C for about 20 minutes, One layer of nitrocellulose-based clear lacquer is formed on the diaphragm base material 1a.

Next, a water-soluble emulsion type vinylidene chloride resin with a concentration of 40 to 50% by weight is applied to the clear rough car resin layer 1b.
Since this coating is a water-soluble resin, it can be easily applied with a brush.

The diaphragm 1 made in this way and the UKP20″SR
A diaphragm molded only from pulp fiber of
d) , internal loss δ×102, propagation speed iwo]X 10
” (cm/sec) and other physical properties are compared and shown in the table below.

As is clear from the above table, the density ρ of the diaphragm 1 of the example is slightly larger than that of a diaphragm made only of pulp fibers of USP 20°SR, but it is much smaller and lighter than a polypropylene diaphragm. Ru.

Furthermore, the Young's modulus is also larger than that of a polypropylene diaphragm.

Furthermore, the internal loss is the same as that of a diaphragm made only of pulp fibers, and the propagation speed is also the same.

Frequency characteristics A of a speaker using the diaphragm of this example
FIG. 3 shows a comparison between this and the frequency characteristic B of the speaker using the polypropylene diaphragm.

This frequency characteristic A shows a flat frequency characteristic characteristic of a diaphragm made of natural fibers and a characteristic that is more recent than the frequency characteristic B.

〔Effect of the invention〕

As mentioned above, the diaphragm of the present invention has physical properties similar to those of a pulp fiber diaphragm using natural fibers, and has the ability to penetrate into the nitrocellulose resin layer on its surface and into the base of the diaphragm. A pinhole-free waterproof and water return layer is formed by the vinyl resin layer formed without pinholes.

Therefore, despite being waterproof and water exchangeable, the diaphragm exhibits a flat sound pressure frequency characteristic similar to that of a pulp fiber diaphragm using natural fibers, and also has excellent surface gloss.

Unlike a diaphragm molded from a single metal, it is easy to manufacture and process the nitrocellulose resin layer on the surface of the diaphragm base material, and a vinyl resin layer is formed on top of the nitrocellulose resin layer. Since it is inexpensive, it has the advantage of being able to be provided at a low cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is an enlarged view of the circular portion of Fig. 1, and Fig. 3 is a comparison of sound pressure frequencies between this embodiment and a conventional polypropylene diaphragm. It is a characteristic diagram. DESCRIPTION OF SYMBOLS 1... Diaphragm, la... Diaphragm base material, 1b... Nitrocellulose resin layer, 1c... Vinyl resin layer. Patent applicant Pioneer Corporation Mogami Electric Co., Ltd.

Claims (1)

[Claims] A nitrocellulose-based resin layer is provided on a diaphragm base material formed into a diaphragm shape mainly composed of natural fibers by surface layer forming means such as impregnation or coating, and a nitrocellulose resin layer is provided on the surface by surface layer forming means such as painting or coating. , a speaker diaphragm characterized by being provided with a vinyl resin layer.