JPS63280600A - Composite diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a disphragm with desired property by adhering and laminat ing a metallic layer and a thremoplastic resin layer by a hot-melt adhesives. CONSTITUTION:A metallic layer 1a and a thermoplastic resin layer 1c are laminated by a hot-melt adhesives 1b. At the time of press forming, the hot-melt adhesives 1b is softened and the lubricant function between different kinds of materials is enhanced and elongated in response to the elongation of the metallic layer 1a and the synthetic resin layer 1c and uniform tension is given by viscous resistance acting on the entire face of the adhesive face. Thus, the disphragm having proper property is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in speaker diaphragms, particularly composite diaphragms in which a metal layer and a thermoplastic resin layer are laminated.

[Conventional technology] The diaphragms of conventional speakers for medium and high frequency reproduction are: ■ A diaphragm formed by molding a light metal part such as titanium or aluminum, or ■ A diaphragm made of a woven or nonwoven fabric impregnated with a thermosetting resin such as phenolic resin. After molding, acrylic resin etc. are applied.
The so-called soft dome imaging plate ■A diaphragm made of synthetic 7 resins such as polypropylene and polyetherimide.

■A diaphragm made of synthetic resin as a base and coated with the light metals, carbon, diamond-like carbon, etc., using vapor deposition techniques such as ion blating; ■A composite diaphragm in which a metal layer is bonded to a synthetic resin layer (a diaphragm plate) , etc. have been considered and put into practical use.

[Problems to be Solved by the Invention] However, each of the above-mentioned conventional diaphragms has advantages and disadvantages, and it has not been possible to provide a diaphragm having desired physical properties.

For example, the metal diaphragm mentioned above has a high Young's modulus of the material itself (5 to 7 x 10" dyn/cIi or more), so it has high rigidity, a wide piston sensing area, a high high-frequency reproduction limit frequency, and heat resistance. It has advantages such as good environmental resistance such as high thermal conductivity, high heat dissipation effect of the voice coil and good input resistance characteristics, but low internal loss (tan δ - 0.02 or less). Therefore, there is a problem in that significant peak dips occur due to high-frequency resonance in a frequency band above the high-frequency reproduction limit frequency, and harmonic distortion increases significantly.

In addition, the [Soft Dome] noise plate has a significantly smaller occurrence of peaks and dips above the high-frequency reproduction limit frequency than the metal imaging plate, but is inferior in reproduction band, environmental resistance, and input resistance characteristics.

In addition, the synthetic resin diaphragm (■) has a large internal loss (tan δ = 0.09'') like it is made of polypropylene resin.
The imaging plate has the characteristic of minimizing the occurrence of peaks and dips above the high-frequency reproduction limit frequency, and has high heat resistance such as polyetherimide resin (heat distortion temperature 150°C).
) A diaphragm with characteristics, each having its own characteristics with respect to some of the desired physical properties, but overall, compared to the above-mentioned diaphragms (■) and (■), it has intermediate properties in terms of rigidity and internal loss values. Therefore, the scope of application was limited.

In addition, the composite diaphragm (■) includes the metal pickup plate and the synthetic resin 1.
This was designed to bring out the advantages of each of the sliding plates, but if the coating layer is made thicker to achieve the desired stiffness, etc., the generation of residual stress peculiar to the deposited material and the synthesis Since there is a problem of poor adhesion with the resin layer and easy peeling, it is practical to coat a synthetic resin layer with a thickness of about 30 to 50 mm with an extremely thin vapor deposition layer of about 0.02 to 0.2 m. Although attempts have been made, the coating layer has not been able to sufficiently improve mechanical properties such as the above-mentioned increase in rigidity with such a thickness.

Furthermore, in the composite diaphragm described in ■, both layers are bonded together, so there are fewer restrictions on the thickness of the metal layer. Press molding is difficult because both layers tend to separate due to the difference in elongation, and the metal layer with small elongation tends to break, and bonding both layers together after molding has problems with the dimensional accuracy of both. Ta.

[Means for Solving the Problem] The present invention is a composite imaging plate for a speaker in which a metal layer and a thermoplastic resin layer are laminated and bonded using a hot-melt adhesive.

[Function] During press molding, the hot melt adhesive softens and acts as a lubricant between different materials, extending in accordance with the respective extensions of the metal layer and synthetic resin layer, and acting on the entire surface of the bonded surface. By applying a uniform tension force using viscous resistance force, it is possible to press-form a composite sheet in which a metal layer and a synthetic resin layer are adhesively laminated. It is possible to provide a diaphragm that provides the following physical properties.

[Example] (Example 1) Titanium foil (JIS
As shown in Figure 2, a TP28R, O material 10 thick > 18 is coated with a hot melt type butyl rubber adhesive 1b dissolved in a mixed solution of methyl ethyl ketone and ethyl acetate (volume ratio 1:1). Spray coat to a dry thickness of approximately 2 mm, and with the coated surface retaining some tackiness, prepare a polypropylene resin film (25M thick> Titanium layer 1a (10
1II11 thickness)・Hot melt adhesive layer 1b (2 cut thickness)
- A laminated composite sheet 1 having a polypropylene resin layer 1C (25N1 thickness) was obtained.

A dome-shaped imaging plate is obtained by drawing the composite sheet 1.

That is, as shown in FIG. 3a, the composite sheet 1 is sandwiched and fixed between an upper mold pad 2a and a lower mold pad 2b which are vertically movable so that the titanium layer 1a faces the convex metal fitting 2C, and the tip is formed into a dome. The upper and lower butts 2a and 2b are lowered (FIG. 3b) until the composite sheet 1 comes into contact with the top of the convex mold 2C which is formed into a shape and heated to 130 to 140°C.

Next, the upper and lower bats 2a, 2b are further lowered,
The composite sheet 1 is shaped along the tip shape of the convex mold 2C (Figs. 3C and 3d), and the titanium layer 1a and polypropylene resin layer 1b shown in Fig. 1 are bonded and laminated using a hot melt adhesive 1C. A dome-shaped diaphragm having a composite structure with a total height of 6.3 m and a diameter of 25# was obtained.

During the above drawing process, the heat of the mold is transferred to the titanium layer 1.
a→hot melt adhesive layer 1b-polypropylene resin layer 1C at a speed such that the hot melt adhesive 1b is softened and the polypropylene resin 1C is heated to a temperature at which it can be molded and drawing processing can be achieved. It was necessary to move the upper and lower bats 2a, 2b, and in the example, it took 20 seconds to complete the molding from the state shown in FIG. 1a to the state shown in FIG. 2d.

(Example 2) Polyetherimide resin film (2
A composite sheet was produced using the same process as in Example 1 using 5 mm thick), and a dome-shaped diaphragm of the same shape was formed by drawing in the same manner as in Example 1 at a mold temperature of 205 to 215°C and a forming time of 40 seconds. I got it.

In addition, as Comparative Example 1, titanium (JIS TP28R, O
Dome-shaped diaphragm made of foil (20 mm thick), Comparative Example 2
As Comparative Example 3, a dome-shaped diaphragm was molded from a polyester fiber woven fabric coated with an acrylic resin emulsion (115 thick); as Comparative Example 3, a dome-shaped diaphragm was molded from a polypropylene resin film (38 m thick); as Comparative Example 4: Polyetherimide resin film (3
Table 1 shows the results of measuring various physical properties of the dome-shaped imaging plates molded with a dome-shaped imaging plate of 8tIIrI thickness) in conjunction with the dome-shaped imaging plates of Examples 1 and 2. ci surface density: g/100 crA Heat deformation temperature: °C Furthermore, a speaker was assembled using the same parts as the dome-shaped sliding plates of Comparative Examples 1 and 4 and the dome-shaped moving plate of Example 2. When the frequency characteristics of each speaker were measured, the results shown in FIG. 4 were obtained.

[Effects of the Invention] According to the present invention described in the above embodiments, when compared with conventional imaging plates, the Young's modulus is the second largest after that of a titanium diaphragm, and when compared with a titanium diaphragm, tan δ increases significantly.

Further, the heat deformation temperature is 150° C., which is a value that poses no practical problem.

Also, when looking at the frequency characteristics, it can be seen that according to the embodiment of the present invention, the occurrence of peak dips due to high frequency co-photography is extremely small, and harmonic distortion is small.

Furthermore, the present invention has the effect that a metal/synthetic resin composite sheet can be formed by using a hot-melt adhesive.

In other words, in conventional composite sheet forming, the surface that is in contact with the convex metal fitting during the drawing process is shaped along the surface of the convex metal fitting, but radial wrinkles occur in the areas that are not in contact, and the upper and lower parts are As the bat descends, the wrinkles are extended and follow the convex metal fittings.

At this time, each layer of the composite film is adhered and their own stretching is inhibited, so the difference in stretching causes a mutual pulling force to act through the adhesive, and this acting force depends on the state of wrinkles. As a result, the titanium layer, which is weak in tensile force, breaks due to uneven tension acting locally.However, in this invention, the hot melt adhesive softens during drawing. However, the tension force due to viscous resistance is applied equally to both sides of the titanium layer and the synthetic resin layer, and a force that suppresses the generation of wrinkles in the titanium layer acts, and the difference in elongation between the titanium layer and the synthetic resin layer is Since it is buffered by the flow deformation of the adhesive, the tension that partially draws the titanium layer and the synthetic resin layer directly against each other is reduced, and breakage of the titanium layer can be suppressed.

Further, as mentioned above, the hot melt adhesive softens and flows during drawing, so no adhesive portions are formed and the adhesive strength is high.

In addition, since there is no non-glue portion of the adhesive, the thickness of the adhesive can be limited to the minimum necessary thickness, so a lightweight diaphragm can be provided.

Further, the hot melt adhesive used in the present invention is preferably made of a material having a larger internal loss than the metal layer and the resin layer so as to obtain a large restraint type vibration suppressing effect.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a diaphragm according to an embodiment of the present invention, Fig. 2 is a process diagram for manufacturing a composite seal in an embodiment of this invention, Fig. 3 is a drawing process diagram of the same, and Fig. 4 is a diagram of an embodiment of the present invention. and FIG. 7 is a frequency characteristic diagram of each speaker using a diaphragm of a comparative example. Patent applicant: Onkyo Co., Ltd. +”L Winding 0-1 and January

Claims (1)

[Claims] A composite diaphragm for speakers characterized by a metal layer and a thermoplastic resin layer bonded and laminated using a hot-melt adhesive.