JPS58131894A - Loudspeaker - Google Patents

Abstract

PURPOSE:To eliminate influence of humidity, and also to obtain an ideal attenuation characteristic, by using a super-elastic alloy as a base material of a diaphragm. CONSTITUTION:Such alloys as Ti-Ni, Ti-Ni-X (X: Cu, Fe, Cr, etc.), Cu-Zn-Al, etc. are called shape memory alloys. These alloys become a super-elastic alloy showing a deformation movement like rubber, by setting a inverse transformation end temperature to a room temperature or below. That is to say, a large elastic strain area is realized, and since elastic hysteresis of a base material is large, an attenuation characteristic against vibration is excellent. Accordingly, if it is used for a diaphragm 6 of a loudspeaker, generation of divided vibration is reduced remarkably, and it is possible to improve a frequency charactoeristic at the time of large amplitude or in intermediate and high temperature areas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker capable of improving sound quality, and particularly relates to an improvement in a diaphragm.

Generally, fibrous cones or diaphragms such as paper or motherboard are used as materials for speaker diaphragms, but these tend to absorb moisture, so the sound quality is easily affected by humidity, and they also have low bending rigidity and internal loss. Therefore, it has the disadvantage that it tends to cause distortion at large amplitudes or in the middle and high frequency ranges, and has poor moldability. Therefore, in order to solve the above drawbacks, composite plates using metal veneers or honeycomb sandwiches, for example, have been provided, but these have a small vibration loss coefficient, that is, internal loss, and have poor damping characteristics, so they are not susceptible to resonance. This may cause split vibrations, etc., and is far from perfect in suppressing the occurrence of distortion.

The present invention was made based on the above circumstances, and its objectives are to be able to exhibit stable performance without being affected by humidity, have good workability, and have high internal loss and damping characteristics as a diaphragm. The objective is to provide a speaker that provides excellent sound quality.

That is, the present invention is a speaker using a superelastic alloy as the material of the diaphragm.

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1 is a frame, 2 is a yoke, and 3 is a permanent magnet. A cone-shaped diaphragm 6 is supported on the frame 1 via a support member, that is, an edge 4 and a spider 5. 7 is Dust Kya, f. Also, what about the center of the diaphragm 6? A voice coil 8 is provided, and a pole piece 9 is inserted into the voice coil 8. The above configuration is similar to a conventional cone-shaped speaker.

In the present invention, a superelastic alloy is used as the material for the diaphragm 6. Superelastic alloys include, for example, Ti-Ni,
It is an alloy represented by Ti-N1-X (X: Cu * Fe + Cr, etc.), Cu-Zn-AA', etc.
All of these are also called shape memory alloys because they have a shape memory effect due to thermoelastic martensitic transformation. These alloys can have a reverse transformation end temperature (Af point) below room temperature by applying a predetermined composition and heat treatment, and as a result, they have a property called superelasticity or pseudoelasticity at room temperature. Superelasticity is the property that even if an external stress is applied to cause an apparent plastic deformation by straining the material beyond the yield point, it will return to its original shape before deformation when the external stress is removed. It exhibits rubber-like deformation behavior.

That is, it has a large elastic strain region and also has a large elastic hysteresis due to internal friction of the material itself, so it has excellent vibration damping characteristics.

As an example, FIG. 2 shows a tensile stress-strain curve of a Ti-(51 at %) Ni alloy that was vacuum-heated at 900° C. and then water-quenched. This alloy completely returns to its original shape in the elastic region up to a strain of 7.5%, and the elastic hysteresis increases as the strain increases. Moreover, when the strain exceeds about 2%, the strain increases with a substantially constant stress.

In addition, the damping characteristics are shown in Fig. 3 for a superelastic Ti-Ni alloy, and Fig. 4 for a general metal material such as steel.The damping coefficient ratio ζ in the bending vibration test is T 1- N
ζ = 0.04449 for i alloy, ζ = 0.0050 for steel
93, it can be seen that the damping characteristics of the superelastic Ti-Ni alloy are very excellent.

Therefore, if a superelastic alloy is used as the diaphragm 6, the occurrence of split vibration at the resonance point of the diaphragm can be significantly reduced, and the frequency characteristics, especially at large amplitudes or in the middle and high frequency ranges, can be greatly improved. can.

Table 1 below compares the vibration loss coefficient η of various materials. Here, the vibration loss coefficient η is a coefficient representing the amount of mechanical work that is lost due to internal friction due to viscosity and converted into thermal energy, and is also simply called a loss coefficient or internal loss. In other words, materials with a large loss coefficient η attenuate vibrations quickly, so when used in speaker diaphragms, split vibrations due to resonance are suppressed, and the sound pressure-frequency characteristics are flat at large amplitudes or in the medium and high frequency ranges. This results in a significant reduction in sound quality distortion.

5-6- As is clear from Table 1, the diaphragm using the superelastic alloy has a specific elastic modulus E//' equivalent to that of the conventional one using paper/gurzo, and has a loss coefficient η. It is clear that this material is superior to paper, plastic, and all other materials in terms of quality, and that it is extremely suitable as a material for diaphragms.

Note that the supporting members such as the edge 4 or the suction guide 5 may be formed integrally with the diaphragm 6 from a superelastic metal. This not only simplifies the structure and makes manufacturing easier, but since the diaphragm and the support member are made of the same material, it is possible to prevent discontinuity in stiffness or mass at the boundary between them. Sound quality can be further improved. It goes without saying that the present invention is not limited to the diaphragm of a cone-shaped speaker, but is equally applicable to the diaphragm of a dome-shaped speaker or a horn-shaped speaker.

As described above, the present invention uses a superelastic alloy as a diaphragm, and can realize superelasticity and high loss.
It can provide ideal damping characteristics as a diaphragm, improving sound quality. In addition, since the diaphragm is made of metal, it does not absorb moisture and exhibits stable performance without being adversely affected by humidity.It is also easy to process into cone or guyaflame shapes, has stable quality, and has specified characteristics. It has great effects such as making it easier to obtain.

Further, in addition to using the superelastic alloy as a single substance, it can also be used by coating other materials by means such as vapor deposition, thermal spraying, or plating, or it can be used as a composite material such as laminated or sandwiched.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a speaker showing an embodiment of the present invention, Fig. 2 is a tensile stress-strain curve diagram of a superelastic Ti-Ni alloy, and Fig. 3 is a damping characteristic of a superelastic Ti-Ni alloy. figure,
FIG. 4 is a diagram showing the damping characteristics of steel materials. 4... Edge (supporting member), 5... Su Guida (supporting member), 6... Vibration plate. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4

Claims (2)

[Claims] (1) A speaker characterized in that a superelastic alloy is used for at least a portion of the diaphragm. (2) The speaker according to claim (1), wherein the diaphragm is integrally formed with a support member supported on a frame.