JPS5822917B2 - speaker diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm for a speaker, and in particular to a diaphragm composed of a paper base material and a metal layer. In general, materials for a diaphragm for a speaker include (a) density ρ;
(O) The elastic modulus E is large, so the vibration propagation velocity is large and the frequency range is wide. (C) The internal loss is appropriately large.

By the way, a diaphragm made of only a paper base material such as cone paper is rigid and has a small Young's modulus, so as the frequency increases from the so-called piston motion range, the diaphragm as a whole does not vibrate as a unit, but produces divided vibrations. It becomes like this.

As a result, there were disadvantages in that the maximum input was small and the frequency range was narrow.

Methods to solve the disadvantages of diaphragms such as diaphragms include diaphragms in which metal films are bonded to both sides of a base material such as paper cone used as a diaphragm, and cones made of beryllium or the like using methods such as vacuum deposition or ion blating. A diaphragm attached to the surface of paper has been proposed.

However, the former case has the disadvantage that the metals that can be used are limited to those that can be rolled.

In the latter case, the vapor deposition operation is performed while being heated in a vacuum, so although there may be no particular problem if the base material is made of plastic film, etc., the base material is hydrophilic or Those made of water-absorbing materials have the disadvantage that the water contained in the base material evaporates due to this heating, and the quality of the base material changes due to the heat, resulting in a significant drop in sound quality.

The present invention provides a method that does not cause deterioration of the quality of the diaphragm substrate or deterioration of the sound quality, even if the base material is made of pulp material such as corn paper, which cannot be processed by the vacuum evaporation method described above. The purpose is to obtain a diaphragm with a metal film attached to the surface.

That is, in this invention, a predetermined metal is thermally sprayed onto the surface of a base material such as cone paper by plasma spraying or the like.

An example of a manufacturing method for obtaining the diaphragm of the present invention will be described below.

First, form a cone paper into a cone shape, for example, 2 cm thick and about 10 cm in diameter.

This shaping is done by making cone paper, and sometimes it is made into a shape different from the above-mentioned hemispherical shape to a Zorro-like shape, and then it is shaped by press molding or the like and dried.

Next, as shown in the attached drawing, an adhesive material such as aluminum alloy or titanium containing 3% silicon is plasma sprayed onto the surface of the paper cone 1 formed into a cone using a plasma spraying device. For example, the thickness is 0.3
mynt! The metal film 2 is attached so that =.

The carrier gas used in this plasma spraying apparatus is preferably a mixed gas of argon and helium.

The ratio of this mixed gas is, for example, 40 argon per minute.
11 Helium should be supplied at 201 times per minute.

The applied voltage for plasma generation may be set to, for example, 32 cm, and the current used may be set to 800 A.

This plasma spraying has a long range of metal powder to be attached to the base material, so the base material is not heated.
A metal film can be attached to a base material without changing the cone paper due to heat and without impairing the properties of the cone paper.

Comparing the piston motion area, that is, the highest frequency that does not cause split vibration, on the diaphragm obtained by the above plasma spraying treatment and the diaphragm that has not been plasma sprayed, it is found that when a power of 20 W is input, for example, the piston motion area on the diaphragm that has not been plasma sprayed, and the maximum frequency that does not cause split vibration. For those with no cone paper, the piston motion range was up to 300 Hz.

However, in the plasma sprayed diaphragm of the present invention, the diaphragm to which the aluminum alloy film containing 3% silicon is attached has a frequency of 480 Hz.

The one with titanium film attached is 570Hzc! =, and the piston motion area becomes wider.

In addition, as shown in the table below, the metal film formed by thermal spraying has a smaller Q value of resonance characteristics than a thin metal sheet manufactured by rolling, so it is difficult to obtain excellent damping characteristics as a metal material for diaphragms. can.

The Q value was measured on a 10 mm long x 30 mm wide surface for both those manufactured by rolling and those formed by plasma spraying.
Measurements were made using a single metal material of mm x thickness of 0.2 t.

The reason for this result is not always clearly understood, or it may be that the sprayed film is generally porous, and that slight friction occurs between the sprayed particles even when they vibrate. This seems to be caused by.

As described above, according to the plasma spraying process, a metal film can be attached to a base material, such as pulp material, which is unsuitable for the true nitrogen deposition method, without impairing the characteristics of the base material.

Also, non-rollable metals can be attached to the substrate as a film.

Therefore, since it is possible to attach the most preferable metal to the cone paper as the metal film, it is possible to obtain a diaphragm with a wide piston motion range.

In addition, the plasma spraying method can deposit a metal film at a speed of 1 mm/min, which is about 100 to 1,000 times faster than the true nitride deposition method, which significantly shortens the manufacturing time of a diaphragm with a metal film attached. It is something.

[Brief explanation of the drawing]

The drawing is a sectional view showing the structure of a diaphragm of a speaker according to the present invention. 1... Cone paper (base material), 2... Metal film.

Claims (1)

[Scope of Claims] 1. A speaker diaphragm having a structure in which a plasma-sprayed metal film is attached to the surface of a paper base material.