JPH0583792A - Acoustic diaphragm and its manufacture - Google Patents

Abstract

PURPOSE:To perform the solid forming of the curved-face shape, etc., While the characteristics of the wood which is a natural raw material are made active and to manufacture by using the conventional processing technology by laminating plural special composite sheets and forming them to the curved-face shape. CONSTITUTION:Wood 1 is sliced to a sheet 2 with the prescribed thickness. To a rear surface 2a of the sheet 2, an unwoven fabric 3 composed of adhesive resin is stuck, and made into a composite sheet 4, after that, the drug processing is performed, thus, the composite sheet 4 is softened. Two softened composite sheets 4 or above are laminated, and set into the prescribed die. The composite sheets 4 set to the die are heated, pressurized and molded. Thus, a cone type acoustic diaphragm 5 is completed. Here, by changing suitably the number of sheets to laminate the composite sheets 4, the control of the thickness of the acoustic diaphragm 5 is facilitated, and the design of the acoustic characteristics is facilitated. The moire finishing can be performed at the acoustic diaphragm 5 and the visual effects are also large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic diaphragm which oscillates in response to an acoustic signal and emits an acoustic sound into a space, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a conventional acoustic diaphragm, there is a flat diaphragm based on wood which is a natural material. This flat plate type diaphragm is manufactured, for example, by the following manufacturing method. First, wood is sliced, and the hydroxyl groups of the sliced wood are replaced with acetic acid groups by acetic anhydride to eliminate the water absorption of the wood, thereby increasing the dimensional stability of the wood.
Then, the wood that has been subjected to such a treatment is used as a plywood, and is formed into a flat diaphragm.

[0003]

By the way, since the above-mentioned conventional acoustic diaphragm is limited to a planar shape, it has a curved surface shape such as a cone-shaped acoustic diaphragm of a conventional speaker. However, there is a drawback in that it is difficult to form a three-dimensional object. Therefore, the conventional processing technology cannot be applied, and as a result, the cost at the time of production becomes high.
The present invention has been made under such a background, and while utilizing the characteristics of wood, which is a natural material, it is possible to form a three-dimensional shape such as a curved shape, and moreover, using conventional processing techniques. An object is to provide a sound diaphragm that can be manufactured and a method for manufacturing the same.

[0004]

An acoustic diaphragm according to the present invention comprises sliced wood and a non-woven fabric made of an adhesive resin attached to the back surface of the sliced wood. It is characterized in that a plurality of composite sheets are laminated and formed into a curved shape. Further, in the method of manufacturing an acoustic diaphragm according to the invention of claim 2, after slicing wood, a nonwoven fabric made of an adhesive resin is attached to the back surface of the sliced wood to form a composite sheet, and then the composite sheet. Is softened, and at least two or more of the softened composite sheets are laminated, and then heated and pressed to be molded to produce an acoustic diaphragm.

[0005]

According to the structure of the acoustic diaphragm of the present invention, the specific elastic modulus (E / ρ) and the internal loss (tan) are increased.
High δ) and excellent acoustic characteristics. In addition, claim 2
According to the method of manufacturing an acoustic diaphragm according to the invention described above, the acoustic diaphragm based on wood, which is a natural material, can be formed into a curved shape.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram showing a method of manufacturing an acoustic diaphragm according to an embodiment of the present invention. Hereinafter, the manufacturing process will be described step by step. Process Wood 1 is sliced into a sheet 2 of about 20 to 80 μm (see FIG. 1A). For the brand of wood 1, Sitka spruce wood is the most suitable from the physical property value,
Cedar and beech wood can be used.

Process The composite sheet 4 is obtained by pasting a non-woven fabric 3 made of an adhesive resin (mainly a thermoplastic resin such as polypropylene or polyethylene) on the back surface 2a of the sheet 2 to form a composite sheet 4, which is then treated with a chemical. Is softened (see FIG. 1 (b)). 20-8 for chemical treatment
Softener heated to a temperature of 0 ° C (Treatment liquid blended with natural products based on an aqueous urethane emulsion)
After immersing the composite sheet 4 in the bath for 10 to 15 minutes,
A treatment such as polymerizing the softening agent is performed by heating the softening agent at several temperatures for several minutes.

Steps Two or more of the above-described softened composite sheets 4 are laminated and set in a predetermined mold (see FIG. 1C). The composite sheet 4 set in the mold is heated and pressed to be molded. As a result, the cone-type acoustic diaphragm 5 shown in FIG. 1D is completed. 2 is shown in FIG.
It is an enlarged view of a part 5a of the acoustic diaphragm 5 shown in (d). As for the conditions of heating and pressing, when polypropylene nonwoven fabric 3 is used, the molding pressure is 10 to 50 kg / cm ² at a temperature of 170 to 200 ° C.

Here, FIG. 3 shows a physical property diagram of an acoustic diaphragm material according to an embodiment of the present invention and a conventional example. In this figure, the sound velocity (E / ρ) ^1/2 and the apparent internal loss (tan
δ) is a value measured by the bending resonance method. As can be seen from this figure, the acoustic diaphragm according to the embodiment of the present invention has a high specific elastic modulus (E / ρ) and excellent acoustic characteristics.

In the above-described embodiment, the seat 2
The thickness is about 20 to 80 μm for the following reason. First, if the sheet 2 is too thick, it is generally difficult to form a curved surface during molding, and the softening agent does not sufficiently penetrate into the sheet 2 during the softening treatment. Therefore, the condition of 80 μm or less is the permissible range of the current impregnation conditions in the softening treatment. On the other hand, if the thickness of the sheet 2 is too thin, the mechanical strength of the composite sheet 4 itself decreases, and cracks are likely to occur during processing. still,
The condition of 20 μm or more is the limit value of the current slicer.

Further, in the case where the composite sheet 4 is laminated in the process of the above-described embodiment, if the mechanical strength of the acoustic diaphragm 5 is desired to be increased, the direction of the wood fiber of the composite sheet 4 is changed as shown in FIG. As shown in FIG. 11, the layers are laminated so that the vertical and horizontal directions intersect each other at 90 °. Further, in order to obtain isotropic physical properties (that is, the properties such as tensile and flexural modulus should be uniform regardless of the direction), the direction of the wood fiber of the composite sheet 4 is as shown in FIG. In addition to the vertical and horizontal 90 ° intersections, they are laminated so that they intersect at an angle of 45 °.

Further, the number of composite sheets 4 laminated in the process of the above-described embodiment, that is, the thickness and weight of the acoustic diaphragm 5 is determined by the system design considering acoustic characteristics and the density of the wood 1 itself. It is determined. Considering the acoustic diaphragm 5 according to the present invention as a kind of composite material, if the resin content is reduced within the allowable range and the wood 1 is laminated as much as possible, the physical property values such as the specific elastic modulus (E / ρ) are improved. As a result, the acoustic characteristics, that is, the sound quality is improved.

[0013]

As described above, according to the present invention,
Light weight, high rigidity and specific elastic modulus (E / E) of natural wood
There is an effect that three-dimensional molding such as a curved surface shape can be performed while utilizing the characteristics that ρ) is high and the acoustic characteristics are excellent. Moreover, since the conventional molding technique can be applied, there is an effect that the cost at the time of production does not increase.

Further, by appropriately changing the number of laminated composite sheets, it is possible to easily control the thickness of the acoustic diaphragm. Therefore, it is easy to design the acoustic characteristics. In addition, since it is possible to give the acoustic diaphragm a grain effect, the visual effect is great.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for manufacturing an acoustic diaphragm according to an embodiment of the present invention.

FIG. 2 is a part 5a of the acoustic diaphragm 5 shown in FIG.
FIG.

FIG. 3 is a physical property diagram of an acoustic diaphragm material according to an embodiment of the present invention and a conventional example.

FIG. 4 is a diagram for explaining an example of a method of laminating the composite sheet 4 on the acoustic diaphragm 5.

FIG. 5 is a diagram for explaining another example of a method of laminating the composite sheet 4 on the acoustic diaphragm 5.

[Explanation of symbols]

1 ... Wood, 2 ... Sheet, 3 ... Nonwoven fabric, 4 ... Composite sheet, 5 ... Acoustic diaphragm.

Claims (2)

[Claims] 1. A plurality of composite sheets composed of sliced wood and a nonwoven fabric made of an adhesive resin attached to the back surface of the sliced wood are laminated to form a curved shape. Characteristic acoustic diaphragm. 2. A composite sheet obtained by slicing wood, sticking a non-woven fabric made of an adhesive resin to the back surface of the sliced wood to form a composite sheet, and then softening the composite sheet to soften the composite sheet. A method for manufacturing an acoustic diaphragm, comprising laminating at least two sheets, and then heating and pressing to form the acoustic diaphragm.