JPS59218096A - Manufacture of diaphragm for speaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a diaphragm for a speaker, and particularly to a method of manufacturing a diaphragm for a speaker using a plasma spraying method.

A speaker diaphragm has a high elastic modulus (Young's modulus E) and a low density (P), that is, a specific elastic modulus of 2/.

13%, which is desired to have a larger internal loss and appropriate internal loss, is required to be strong in the treble range as a diaphragm for medium and high frequencies. In order to satisfy these demands, we developed Al2O3, which has a material with a significantly higher specific elastic modulus than the metals such as A4XTi and Mg that have been used so far.
It was considered to use ceramics such as SiC, B, and C. However, ceramics cannot be rolled or pressed like metals, and ordinary sintering methods have a high shrinkage rate and large deformation, so a thin and complex shape (such as a dome shape) is required. Although it is difficult to manufacture plates with high precision (and at low cost), it is possible to use plasma spraying as a means of manufacturing them fairly easily.

One of these methods is to attach ceramics in the form of a thin plate by plasma spraying onto a mold made of carbon steel or the like that corresponds to the desired shape of the diaphragm, and then separate the thin ceramic plate from the mold to form the diaphragm. There is.

FIG. 1 is a block diagram showing a general method for manufacturing a diaphragm using plasma spraying, in which a plasma spraying device 10, a mold 1
2 is used. Plasma spray equipment 10 This plasma flame io
There is a thermal spray material tOC etc. that is introduced into a. The mold 12 is formed of carbon steel or the like to correspond to the desired shape of the diaphragm (the illustrated example is a dome shape), and its surface is hard and extremely smooth.
, 03, B4C, etc. are formed. After thermal spraying as shown in FIG. 2, this thin plate 14 can be separated from the mold 12 as shown in FIGS. 2(a) to 2(b) when the temperature reaches room temperature, and a diaphragm having a desired cross-sectional shape can be obtained.

Although the diaphragm 14 obtained by this method is influenced by manufacturing conditions, it generally has a specific elastic modulus when compared with metals such as T1 and A1. 2/T is high, and since the pores are uniformly distributed in the ceramic thin plate in plasma spraying, the internal loss is high, and it has excellent characteristics as a diaphragm.

However, because the diaphragm 14 is made of ceramic alone and due to the above-mentioned porosity, the bonding force between ceramic particles is small and it is weak against impact force. Also,
As shown in FIG. 3(a), the surface of the diaphragm 14 made by plasma spraying is generally not very smooth, and the surface roughness on the spraying device side t4b is rougher than on the mold side 14a. In order to increase the mechanical strength of the diaphragm 14, it is impregnated with resin and hardened. This resin impregnation is carried out by immersing the entire diaphragm 14 in a resin solution, or applying the resin solution to the surface of the diaphragm by spraying or brush painting, and hardening it by heat treatment or the like. In this case, a resin layer that permeates in the direction of the arrow is formed in the state shown in FIG. The irregularities on the side surface are filled in to make the surface smooth.As a result, the mechanical strength is increased, but all the pores 18 are filled, resulting in a decrease in internal loss and deterioration of speaker characteristics.

By the way, it has been found that if the surface 14a of the speaker diaphragm from which sound is radiated is appropriately rough, the radiated sound will be clear and mellow. In other words, it is preferable that the sound radiation surface side of the speaker diaphragm is not smooth. However, when the entire surface of the diaphragm 14 is impregnated with resin as described above,
As a result of uniformly smoothing the rough surface characteristic of plasma spraying, the emitted sound has the disadvantage that it becomes more like a metallic, clanging sound. In addition, when B4C is sprayed as a ceramic, B4C in the sprayed state is
The surface is satin-like and matte, with a dark blackish-gray color, and the appearance also has a color tone unique to the material.

However, according to the above-mentioned resin impregnation method, the resin comes out on the surface of the diaphragm, so there is a drawback that the color tone peculiar to the above-mentioned material is lost.

The present invention has been made in view of the above-mentioned conventional problem, and its purpose is to provide a method for manufacturing a speaker diaphragm that obtains a speaker diaphragm that is excellent in sound quality, mechanical properties, and color. There is a particular thing.

In order to achieve the above object, the present invention involves spraying ceramics by plasma spraying onto a mold having a desired shape with a smooth surface, forming a ceramic layer, and then releasing the ceramic layer from the mold to form a ceramic layer. A diaphragm is produced by impregnating resin from the crystal surface and hardening it to an extent that the sound does not reach the surface from which sound is radiated.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 4 is a process diagram showing the method for manufacturing a speaker diaphragm according to the present invention, including a step 20 of spraying ceramics onto a mold, a releasing step 22 of releasing a thin ceramic plate, that is, a diaphragm from the mold, and a step 22 of releasing the diaphragm from the mold. resin impregnation step 24 for reinforcement;
It consists of a hardening treatment step 26.

Here, the thermal spraying step 20 and the mold release step 22 are the same as in the conventional manufacturing method of a speaker diaphragm. According to the actual inspection, the surface 28a of the obtained ceramic diaphragm 28 in contact with the mold was quite smooth as shown in FIG.
[(Sound radiating side) 28b has a larger surface roughness than iJa. Qi (L18 also exists quite a lot,
The average porosity of those manufactured under standard conditions was 15%. In the resin impregnation process, the diaphragm 28 manufactured as described above is mixed with resin at a viscosity that does not reach the surface 28b, and an appropriate amount is applied from only the surface 28b by spraying, brush painting, etc. It permeates in the direction of the arrow.

Note that the material, viscosity, and impregnation of the resin affect the sound quality and mechanical strength of the speaker as well as the distribution of the resin in the ceramic. As an example, the basic composition of the resin is epoxy resin and BT#1'4 resin (bismaleimide, triazine resin) in a ratio of 1=3, and the weight is about 2.
After uniformly diluting with a solvent of twice the amount of MEK (metelle, ether ketone), this solution was impregnated in an amount of 8% based on the weight of the imaging plate.

Thereafter, a hardening treatment was performed under the conditions shown in FIG. In addition, in FIG. 6, the horizontal axis represents time and the vertical axis represents temperature.

As shown in FIG. 5(b), the imaging plate 28 treated as described above has less impregnated resin as it goes from the surface 28a side of the diaphragm 28 toward the surface 28tl side, and is hardly present on the surface 28b. That will happen.

As described in detail above, according to the present invention, a single ceramic imaging plate manufactured by a plasma spraying method is impregnated with resin from the opposite side so as not to reach the sound emitting surface, and the resin is impregnated in the vicinity of the sound emitting surface. Since the state was maintained in the plasma sprayed state, the bond between the ceramic particles was increased and the mechanical strength was increased. In addition, the photographing plate 28 has a sound radiation surface 2'8.
Since the surface condition of t) is not damaged, it has an appropriate internal loss, and a unique surface sound can be generated due to the unevenness existing on the sound emission surface side 281). In addition, when assembled as a speaker system, the sound emitting surface 2'8b, which may be exposed to the human eye, remains sprayed.
It has a particularly remarkable effect as a speaker diaphragm, such as being able to maintain the unique color tone of the ceramic material, and is of high industrial value.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a method of manufacturing a speaker diaphragm by plasma spraying, Figs. 2(a) and (b) are cross-sectional views of the diaphragm before and after demolding, and Figs. 3(a) and ( b) is an enlarged cross-sectional view showing the state of the diaphragm before and after resin impregnation by the conventional manufacturing method, and a diagram showing the direction of resin impregnation; FIG. 4 is a process diagram showing the method for manufacturing the speaker diaphragm of the present invention; FIG. (a),
(1)) is an enlarged cross-sectional view showing the state of the diaphragm before and after resin impregnation according to the manufacturing method of the present invention, and a view showing the direction of resin impregnation, and FIG. 6 is a view showing resin curing treatment conditions. In each figure, the same members are given the same symbols, IO is a plasma spraying device, 712 is a mold, +4 is a ceramic thin plate, 16
1 is a resin, 18 is a pore, 2o is a thermal spraying process, 22 is a mold release process, 24 is a resin impregnation process, 26 is a hardening process, and 28 is a diaphragm. Agent: Patent attorney Masuo Oiwa (and 2 others) Figure 1 Figure 2 (a) (b)

Claims (1)

[Claims] (1) A ceramic layer is formed by spraying ceramics using plasma spray pressure onto a mold with a smooth surface and a desired shape, and then this ceramic layer is released from the mold to reach a surface where sound can be radiated to the ceramic layer. A method for producing a diaphragm for a speaker, characterized in that the diaphragm is obtained by impregnating a resin from the back side to such an extent that the diaphragm is hardened.