JPH0783517B2 - Vibration plate for audio equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a diaphragm for audio equipment, and more particularly to a diaphragm using aluminum as a metal material. This type is used as a diaphragm for audio equipment such as speakers.

BACKGROUND OF THE INVENTION When a metallic material is used as a diaphragm, various measures are taken to improve its acoustic characteristics. That is, a metal material generally has a high resonance sharpness (that is, a low internal loss), so that a sharp peak is generated in the vicinity of fh (a wide-range limit frequency), and a peculiar coloration causes an unpleasant sound. There are some difficulties. The difficulty is
It is possible to solve the problem to some extent by using a vibration-damping metal material itself (a vibration-damping alloy such as Al-Zn, Mg-Zr, or Ti-Ni) or by combining a metal material and a vibration-proof material. For example, aluminum base material can be solved to some extent by applying anti-vibration rubber or resin (synthetic rubber, natural rubber, foamed urethane or other elastomers), etc., or by laminating it to create a vibration-damping structure. Is. This vibration damping structure is generally performed not only with respect to the anti-vibration effect, but also with consideration of durability (in particular, improvement of corrosion resistance of metal by coating and laminating) and appearance. Examples include resin coating of urethane, epoxy, acrylic, etc. on the surface of the material, and laminating with an elastic film such as olefin, amide, or ionomer. However, if the vibration damping material is increased for the purpose of enhancing the vibration damping effect, the processing thickness increases in proportion to it, and the weight increases, leading to a decrease in sensitivity, which is a problem.

On the other hand, the metallic material used as the braking plate is required to have improved durability and high strength, and in particular, it is desired to improve the specific elastic modulus (higher sound velocity). However, such improvement in mechanical strength and increase in elasticity are generally in a contradictory relationship with the above-described reduction in resonance, and it is difficult to achieve both at the same time. In addition, the increase in the density of the material to increase the strength and the increase in the total weight lead to a decrease in sensitivity. In addition, as conventional strength and elasticity techniques, metal boride, carbide, nitride, oxide, etc. are deposited on the surface of the material by means of CVD, PVD (sputtering, plasma spraying, ion beam), etc. Alternatively, thermal spraying of ceramics may be mentioned, but these require a large-scale device, are technically advanced, and cannot be easily applied. In addition, it may be possible to combine them with other metals such as a clad structure to form a composite structure, or to alloy them to achieve improved strength, but this is related to the problem of vibration damping and the problem of increased weight.・ When considering productivity, processability, and other points, it is not always satisfactory.

Conventionally, for example, aluminum is used as a metal material used for the diaphragm, which should be satisfied in terms of workability, durability, productivity, and cost in consideration of moderate acoustic physical properties, but the internal loss is small ( The problem is that the resonance sharpness is high) and the strength is insufficient, which limits its practical use. Therefore, when it is desired to extend fh to a higher position, or when it is desired to suppress the peak in the high frequency range and flatten the band sensitivity, it is disadvantageous to use aluminum by itself. That is, from the above circumstances, in order to use aluminum as a metal material, it is strongly desired to reduce the resonance and increase the strength.

As described above, in order to solve the above-mentioned problems of the metal material, various methods for improving the composite have been adopted. For example, a typical method is used to form a honeycomb diaphragm. In this method, the reproduction band range is determined by D / σ (D is the bending rigidity and σ is the surface density). However, since the bending rigidity D is increased in the honeycomb structure, the reproduction band range can be expanded. However, in order to further expand this range, it is necessary to further increase the bending rigidity D. Moreover, it is desirable to further reduce the surface density σ depending on the material used as the surface material. For this purpose, it is necessary to make the surface material lighter and stronger. Furthermore, in order to suppress the generation of sharp peaks (high resonance sharpness) of higher-order modes in the honeycomb diaphragm, it is necessary to improve the internal loss of the surface material, that is, to lower the resonance as described above. is there. Also, in terms of contributing to high sensitivity, it is desirable to reduce the density.

These circumstances are the same in vibration systems other than the honeycomb vibration plate, and it is desired to reduce the resonance, increase the rigidity, and decrease the density of the metal material used as the vibration plate.

In terms of high rigidity, when aluminum is used as the aluminum diaphragm, the rigidity of the diaphragm can be increased simply by providing anodized films on both sides of the aluminum. However, on the other hand, the sound reproduced from an audio device such as a speaker using the finished diaphragm becomes a noisy sound. In addition, a technique has been proposed in which aluminum is anodized and the pores of the alumina layer are filled with nickel or molten aluminum to improve the acoustic characteristics (Japanese Patent Publication No. 57-13198, 5).
7-11553), however, these techniques are unstable because they have a weak diffusion force of the filling material into the pores, have a problem of adhesion. In the case of nickel filling, the density is high, which is a disadvantage. It has also been proposed to form a large number of small holes in a metal substrate such as aluminum, and to fill the small holes with a substance with large internal loss such as synthetic resin or oil (Japanese Patent Publication No. 55-15156).
This also has a problem in stability, and it is difficult to apply it to an anodic oxide film having fine pores. In addition, there is a problem of deterioration of the filled synthetic resin and oil. Moreover, the density becomes large. Further, a speaker diaphragm has been proposed in which an alumina layer is formed on an aluminum substrate by anodizing and the pores of the alumina layer are filled with a filler made of Ni, Cr, Fe, a synthetic resin, or the like. However, this also has the same drawbacks as the above-mentioned respective prior arts.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the resonance sharpness of aluminum used as a metal material (that is, increase the internal loss) and increase the bending rigidity to increase the bending rigidity in the high range. It is possible to prevent the occurrence of peaks, expand the playback band range, and modify the eigen sound, and without increasing the density, not particularly increasing or decreasing the weight, reducing the sensitivity, and evenly. It is intended to provide an advantageous diaphragm for audio equipment, which can be easily realized at low cost.

[Structure of Invention]

The diaphragm for an audio device of the present invention is a diaphragm for an audio device in which an anodized film is formed on both surfaces of a foil-shaped aluminum,
The diaphragm for an audio device is characterized in that the ferric oxide is generated in at least a part of the fine pores of the anodic oxide film formed on both sides of the aluminum.

In the present invention, at least iron hydroxide is generated in the fine pores formed in the anodized foil-shaped aluminum oxide film.

The iron hydroxide can be generated in the fine pores by using an iron complex salt and precipitating the iron hydroxide by hydrolysis of the complex salt. For example, oxalic acid second
An iron ammonium salt is used to hydrolyze and precipitate the iron hydroxide (which is thought to actually have a complex chemical structure as iron oxide or its hydrate) to form an oxide film. Can be generated in the micropores of

[Operation of the invention]

According to the present invention, when aluminum is used as a vibrating body, it is possible to form an anodized film on both sides of aluminum to enhance the rigidity when viewed as a vibrating plate structure, and the anodized film itself is Since the loss is small, the Q is increased. In order to reduce this, iron hydroxide is generated in the fine pores of the anodic oxide film to lower the Q, and the internal loss is increased to flatten the frequency characteristic. I did it. Further, by generating iron hydroxide in the fine pores, the adhesion and instability can be improved as compared with the case of filling a synthetic resin or a metal such as Ni as in the conventional example.

That is, in the present invention, the iron hydroxide generated in the fine pores of the anodic oxide film prevents the occurrence of peaks in the high frequency range due to the improvement of the resonance sharpness (internal loss) of the metal material, and produces a characteristic sound. It serves the function of improving.

In addition, the present invention does not cause variations due to the direction of the gun such as vapor deposition or ion beam, a uniform structure is obtained, the sensitivity does not decrease, and the weight does not particularly change. Moreover, such an effect can be achieved by a simple technique, and a low cost can be obtained.

The diaphragm obtained by the present invention is used for various purposes, for example, in the shape of a flat plate, a circle, a dome, etc., and can be used for various speakers, and there is no particular limitation as to the use of the diaphragm.

[Examples of the Invention] Some of the examples of the present invention will be described below. However, as a matter of course, the present invention is not limited to the following examples.

Example 1 In this example, foil-like aluminum was used and used as a skin material of a honeycomb structure. Further, in this example, when iron hydroxide (or iron oxide or a substance which is considered to have a structure as its hydrate) was formed in the fine pores of the oxide film, it was formed by the dipping method.

Hereinafter, this embodiment will be described.

In this example, first, aluminum foil (several μ to several tens of μ
(Thickness) is anodized to form an anodized film on it. The conditions for this anodic oxidation are 15 wt% sulfuric acid and 25 ° C.
At 1 A / dm ² for 18 minutes. The anodic oxide film thus obtained is α-mono-hydrate (Al ₂
O ₃ · H ₂ O) film, the film thickness is about 6μ, and the diameter of the fine pores is about 200Å.

Regarding the aluminum thus anodized, ferric oxalic acid ammonium salt (NH ₄ ) ₃ Fe (C
₂ O ₄ ) ₃ · 3H ₂ O is hydrolyzed to precipitate a hydroxide. In this example, specifically, ferric ammonium oxalate was previously dissolved to prepare a 0.3 wt% aqueous solution, which was heated to 80 ° C. and impregnated with the above anodized aluminum for 30 seconds or more.

As a result, iron hydroxide was produced in the fine pores of the anodic oxide film. Iron hydroxide is considered to be mainly in the form of Fe (OH) ₃ , which is hydrolyzed and produced by the following reaction. It is considered that such iron hydroxide is generated in the micropores due to the rapid progress of hydrolysis especially in the micropores because the micropores are active.

_{(NH 4) 3 · Fe (} C 2 O 4) 3 · 3H 2 O → Fe (C 2 O 4) 3 + 3NH
₄ + 3H ₂ O Fe (C ₂ O ₄ ) ₃ + 6H ₂ O → Fe (OH) ₃ +3 (COO
H) ₂ + 3OH ⁻ The cross section of the material obtained by this example is considered as shown in FIG. That is, an anodic oxide film (alumite layer) 2 is formed on both sides of aluminum 1, and a part of this oxide film 2 is a part (iron hydroxide containing oxide film layer) 3 in which iron hydroxide is contained in the fine pores. It is estimated that In addition, in the immersion method as in this example, iron hydroxide is considered to be generated from the outside of the micropores, so FIG. 1 also shows that, but the micropores completely extend to the inside. When buried, the entire oxide film 2 becomes the iron hydroxide-containing oxide film layer 3. Of course, a material having such a texture structure may be obtained and used depending on the conditions.

The sample obtained in this example has an overall thickness t of about
25 .mu.m, and the thickness t'of the oxide film 2 is about 6 .mu.m.

The following table shows the physical characteristics of the diaphragm prototyped from the sample obtained based on this example.

As is clear from the above table, the resonance sharpness is remarkably lower than that of aluminum, so that the problem of internal loss of aluminum can be solved and the occurrence of peaks in the high range can be suppressed. Further, the elastic modulus is slightly larger than that of aluminum, and as a result, it is expected that the bending rigidity becomes high and the limit frequency becomes high, so that the reproduction band range, particularly in the high range, can be widened. The sample of this example has almost the same density as aluminum and almost no change in weight. Although the density is slightly small, it is expected to contribute to the improvement of sensitivity.

As described above, in this example, a well-balanced vibration plate which could not be obtained by using aluminum alone or its anodized film was obtained.

[Advantages of the Invention] As described above, in the diaphragm for an audio device of the present invention, the resonance sharpness is lowered (that is, the internal loss is increased) and the bending rigidity is increased, so that the occurrence of a peak in a high range is prevented. Prevention, expansion of the reproduction band range, modification of eigen sound are possible, and these are uniform without decreasing sensitivity, and weight is not particularly increased or decreased,
Moreover, there is an effect that it can be easily realized at low cost.

Of course, the present invention is not limited to the above-mentioned embodiments.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention. 1 ... Metal material (aluminum), 2 ... Anodic oxide film,
3 ... Inorganic metal compound-containing oxide film layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Samukawa, Inventor Hiroyuki Samukawa, 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Nobuo Tomiya, 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Masakazu Maejima 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Line Co., Ltd. (72) Inventor Koichi Saruwatari 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Den Line Co., Ltd. (56) Reference JP-A-54-97015 (JP, A) JP-A-56-130490 (JP, A) JP-B-55-14155 (JP, B2)

Claims (1)

[Claims] 1. A diaphragm for an audio device, wherein anodized films are formed on both sides of foil-shaped aluminum, and iron hydroxide is formed in at least a part of the fine holes of the anodized film formed on both sides of the aluminum. A diaphragm for an audio device, which is a product produced.