JPS5985839A - Acoustic diaphragm - Google Patents

Abstract

PURPOSE:To obtain an acoustic diaphragm with improved rigidity and corrosion resistance by using an Mg-Si alloy contg. Mg as the principal component so as to reduce reduction of internal loss by alloying. CONSTITUTION:An acoustic diaphragm suitable for use as a diaphragm for a speaker is obtd. by using an Mg-Si alloy prepared by adding about 0.6-0.8wt% Si to Mg so as to reduce considerable reduction of internal loss peculiar to Mg, to improve the rigidity of the alloy and to inhibit the corrosion. A speaker provided with the resulting diaphragm inhibits remarkably a peak dip especially in a high resonance frequency band. Said alloy is also applicable to a diaphragm for a microphone, the cantilever of a pickup and other object to which a resonance phenomenon is harmful.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in acoustic vibrators such as diaphragms for speakers or microphones, cantilevers of pickups, cartridge shells, tone arms, and turntables.

As an example of this type of vibrating body, let's talk about speaker diaphragms. Conventionally, metal diaphragms for high-pitched speakers include aluminum (A-z) and titanium (Ti).
, duralumin, etc. have been used, but this type of metal has the drawback of extremely low internal loss.

For example, the phantom attenuation index is 0.023. That of duralumin is about 0.81.

Therefore, a speaker having such a metal diaphragm exhibits a significant resonance phenomenon in the high frequency range, resulting in the occurrence of harmful peaks and dips in frequency characteristics.

Therefore, among metals, magnesium has the highest internal loss (
Mf) is considered as the diaphragm material for the speaker.

For example, mr (99,9%) has a damping index of 60.
It reaches approximately 200 times of t.

However, as is well known, My is an extremely active metal, so it has a drawback in that it becomes brittle due to corrosion and rust when applied to diaphragms used in air.

It is possible that

However, although the objective 1 can be achieved to some extent by alloying, on the other hand, alloying reduces internal loss, and the advantage of My, which has a large internal loss, cannot be fully achieved practically.

For example, AZ81B (M f
, 3 h % A Z , 8 Wt % Z n
+ I wt % - M n O,, 8 J, %), the attenuation index becomes 11 and decreases to about the bound of M2.

Therefore, the present invention is an acoustic vibrator which has a small reduction in internal loss due to alloying and is designed to improve rigidity and corrosion resistance. explain.

My-Si alloy whose main component is Mf (Si content 0.7
wt%) was press-formed into a dome shape with a diameter of 25 mm.

A speaker was assembled by combining this with a magnetic circuit, and the frequency characteristics were measured. The results are shown in Figure 1.

In the figure, the dotted line represents the frequency characteristics of a speaker equipped with a diaphragm of the same diameter made of AZ31B.

As is clear from the figure, the speaker equipped with the diaphragm according to the present invention has a significantly extended peak tip, especially in the high resonance frequency band from 12 kllz to 20 kllz, compared to the speaker equipped with the AZ31B diaphragm. .

Furthermore, when the damping index of the My-8-1 alloy used in the diaphragm was measured, a value of 52 was obtained.

This means that the attenuation index is reduced by about 13% compared to M2, and is about 5 times as large as that of AZ31B.

Although the content of Si is limited by its manufacturing method and alloy composition, significant effects can be achieved within the range of 0.6'wt% to 0.8wt%.

As explained above, this invention converts M9 into Fi:I71
+.

It is a vibrating body made of a My-Si alloy with M
It improves the corrosion resistance, which is a drawback of Y, and minimizes the reduction in internal loss.It is used not only for speaker diaphragms, but also for microbon diaphragms, pick amplifier cantilevers, cartridge shells, This can be applied to objects where resonance phenomena are harmful, such as pink-up arms and turntables.

[Brief explanation of drawings]

FIG. 1 is a frequency characteristic diagram of a speaker equipped with a diaphragm according to the present invention and a conventional M2 alloy diaphragm. )i number of sentences (鴫) → %′l Figure

Claims (1)

[Claims] Magnesium (Mf) is the main component.
Mf)-acoustic vibrator made of silicon (Si) alloy.