JPS59138198A - Highly elastic diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a diaphragm having low cost and performance of mass- production regardless of good frequency characteristic and high electroacoustic efficiency by using a new aluminum nitride film. CONSTITUTION:A highly elastic diaphragm is constituted by forming directly an aluminum nitride film 2 on one side of a light metallic base 2 such as aluminum. The aluminum nitride film 2 is formed by taking an aluminum metal as a target, arranging oppositely an aluminum base formed into a prescribed shape and attaching directly the aluminum nitride film 2 on the aluminum base 1 by the DC or high frequency sputtering method in nitrogen and argon atmosphere as mass-production. Further, the thermal expansion coefficient between the base 1 and the film 2 has no difference, no internal distortion exists and the bonding strength of the film 2 is strong. Since the density of the film 2 is small and the sound velocity C is large, the highly elastic diaphragm having a good frequency characteristic and high electroacoustic efficiency is obtained.

Description

[Detailed description of the invention] The present invention relates to a high elasticity diaphragm for speakers.

Theoretically, as a high-elastic diaphragm material for speakers, the density ρ is
(KO/m3) is smaller, and the speed of sound C(m/se
It is well known that the larger the c), the better.

Examples of high elastic modulus materials with small ρ and large C include beryllium (Be) and boron (B).
There is one in which a film of a highly elastic metal such as beryllium (Be) or boron (B) or a compound thereof is formed on one or both sides of a light metal substrate such as ρ).

However, such high-elasticity diaphragms are made of beryllium (Be
) and boron (B) are not only expensive, but
It is difficult to form the film on a metal substrate, and the adhesion of the Be film and B film to the Aρ substrate is weak.

In addition, we have also developed a high-modulus imaging plate in which aluminum (Aρ) is vapor-deposited on a plastic substrate, and titanium (Ti) nitride (TiN) or carbide (TiC) is formed on top of this AN vapor-deposited film. there were. For such diaphragms, the method of forming a TiN film or TiC film on a plastic substrate is complicated, and the method of forming a TiN film or TiC film on a plastic substrate is complicated.
i N film, TiC film) because the thermal expansion coefficients do not match.
The disadvantages are that a special jig is required when forming the film, and even after the film is formed, it retains internal strain and is prone to cracking.

The present invention eliminates all the drawbacks of the conventional high-elasticity diaphragms for speakers as described above. By using a completely new aluminum nitride (AρN) film as the material for the speaker diaphragm, it has good frequency characteristics and Despite its high acoustic efficiency, it is possible to realize a mass-produced, low-cost high-elasticity diaphragm for speakers.

As shown in FIG. 1, the present invention utilizes aluminum (Aρ)
Aluminum nitride (Aρ
A high-elasticity diaphragm is constructed by forming the film 2 of N). AμN1fj2 can be formed in mass production by using aluminum metal as a target and directly depositing the AlN film 2 on the A11 substrate 1 by direct current or high frequency sputtering in an atmosphere opposite the target.

The Aj2N film 2 deposited directly on the /l substrate 1 by such a mass-produced method has a density ρ of 3.05 (K(1/m3),
A material with a sound velocity C of 11.5 (ffl/SeC) was obtained. Conventionally known high modulus materials, such as Aρ
The density ρ and sound velocity C of , Ti, Be, and B are as shown in Table 1, and from this table, AρN used in the present invention exhibits properties almost comparable to Be and B, which are the highest as high elastic materials. I understand that.

Table 1 Furthermore, the high elasticity diaphragm according to the present invention has an Aρ substrate 1 and a
, Q Since there is no difference in the coefficient of thermal expansion of the N film 2, there is no internal strain and the adhesive force of the AρN film 2 is strong. Moreover, since aluminum is cheap, a diaphragm with great industrial value can be obtained at a low price. Furthermore, since AρN, the density ρ of the membrane 2 is small, and the sound velocity C is large, a highly elastic diaphragm with good frequency characteristics and high electroacoustic efficiency can be obtained.

Figure 2 shows an example of Haku, A1 molded into a dome shape.
AρN film 2 is applied only to the dome part, leaving the peripheral part 1a of the substrate 1.
, and the peripheral edge 1a thereof is corrugated in the tangential direction. According to this embodiment, only the dome portion of the Aρ substrate 1 becomes a high-elastic diaphragm, and the corrugation portion becomes a high-elastic diaphragm. Since it is the substrate itself, it becomes a soft corrugation and can easily create good frequency characteristics.

Each of the illustrated embodiments has Aρtill on only one side of the substrate.
However, according to the present invention.

For example, an AρN film may be formed on both surfaces of the AQ substrate, and the formation of the AρN film is not limited to the sputtering method, but a CVD method, an ion blasting method, or the like may be used.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a high elasticity diaphragm according to the present invention, and FIGS. 2(a) and 2(b) are a plan view and a sectional view showing other embodiments, respectively. 1 is a /l substrate, and 2 is an AρN film. Patent applicant Murata Manufacturing Co., Ltd. Figure 1

Claims (1)

[Claims] A high-elasticity diaphragm for a speaker, characterized in that an ARN film is formed on the entire surface or a part of a metal substrate.