JPS59103497A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a diaphragm for speaker by the sandwich construction of low cost by using a 4-methylpenten polymer fibers for a core member as a main body and using a sheet mixed with high elastic fiber such as carbon fiber, alamide fiber and glass fiber as a reinforcement member with heat forming to make the weight of the diaphragm as light as the weight of paper cone. CONSTITUTION:The speaker diaphragm is formed so as to the synthetic fiber made of 4-methylpenten polymer is used as the base member, high elastic fibers such as carbon fibers, alamide fibers and glass fibers are mixed by 5-40% as the reinforcement member, the sheet obtained by paper-making the mixture is formed thermally, and a surface member is bonded on both sides of the core member. The core member 1 consists of an aggregate of six sectorial small pieces 2, the sectorial small pieces 2 are formed in a wave as cross section and plural parallel ribs are provided. Further, the sectorial small pieces 2 are aggregated so that the prolonged line of the ribs are crossed to the center line of the core member 1.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speaker diaphragm having a sandwich structure in which surface materials are bonded to both sides of a core material.

Conventional configurations and their problems Page 1 Generally speaking, it is ideal for the diaphragm of a speaker to have the same phase on its entire surface over the frequency band used, that is, to vibrate as a piston, but during vibration the diaphragm deforms or split vibrations occur. and sound pressure frequency characteristics, φ rate.

The phase characteristics etc. deteriorate, which impedes high-fidelity reproduction.

In order to solve these problems, in recent years, planar diaphragms using a nicham sandwich structure or the like have been adopted.

However, a planar diaphragm made of a honeycomb sandwich structure has a complicated structure and requires dozens of manufacturing steps and many types of components, resulting in a considerable cost increase. It was also difficult to make it inexpensive. Furthermore, due to limitations on the thickness of the constituent materials during manufacturing, it is difficult to reduce the weight of the diaphragm, resulting in a problem that the efficiency of the speaker is low.

OBJECT OF THE INVENTION The present invention overcomes these conventional drawbacks.
It is an object of the present invention to provide a speaker diaphragm having a sandwich structure that can reduce the weight of the diaphragm to be as light as a conventional paper cone and at low cost.

Structure of the Invention The diaphragm of the present invention has a core material mainly composed of fibers of 4-methylpentene polymer, which is said to have the lowest density among plastics, and carbon fibers.

It is used by thermoforming a sheet containing high elastic fibers such as aramid fibers and glass fibers as a reinforcing material, and a diaphragm is made by pasting surface materials on both sides of the core material.

Here, the shape of the heartwood is at least 3 fan-shaped pieces having a plurality of ribs arranged at an angle of non-convergence.
It is a collection of more than one. With such a shape, the elongation of the material after molding is constant no matter which part of the core material is taken, so a homogeneous and lean structure can be obtained. Since the housing is centrally symmetrical, the node at the first resonance frequency has a nearly circular shape, which has the advantage of being suitable for the node drive method.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an embodiment of the present invention, in which numeral 3 indicates a planar diaphragm having a sandwich structure.

It has a circular node circle a6. The open end of the coupling cone 4 is bonded to the circular node 8i1 of the planar vibration 8i1, and the other end is connected to the magnetic circuit via the voice coil 12. 6 is a yoke having a center ball 6; 7 is an annular magnet 7 disposed on the yoke 6;
Reference numeral 8 denotes a plate placed on the magnet 7, which constitutes a magnetic circuit. A magnetic gap is formed between the outer periphery of the center ball 6 and the inner periphery of the -hip plate 8. Also.

The outer peripheral portion of the flat diaphragm 3 is supported by the frame 1o by an edge member 9. The plane diaphragm 3 has its circular node a
The opening of the coupling cone 4 is joined to this portion, and a voice coil 12 wound around a voice coil bobbin 11 provided at the other end is supported by a damper 13 within the gap of the magnetic circuit.

2 and 3 show the above-mentioned planar diaphragm 3. In FIGS. 2 and 3, 1 is a core material, and surface materials (not shown) are attached to the front and back surfaces of the core material using an adhesive. It is attached. The core material 1 is an aggregate of six fan-shaped pieces 2.

Be:.

As shown in FIG. 3, each of the sector-shaped pieces 2 has a corrugated cross-section and has a plurality of parallel ribs. The six sector-shaped small pieces 2 are assembled so that the extension lines of their ribs intersect with the center line of the core material 1. The nodal circular shape of the first resonance of the planar diaphragm thus constructed is formed in a waveform centered on a circle that is approximately 68% of the outer diameter of the diaphragm, as indicated by the broken line in FIG. Specifically, a diaphragm with a diameter of φ2oO9 and a height of emm was created and its frequency characteristics were measured when it was used as a bass speaker.

1. As a material for the core material, 70 parts of 4-methylpentene fiber and 30 parts of carbon fiber (fiber length 6111 m, fiber diameter 10 μm) were added.
A sheet of 1 tsOf//rd was made into a sheet, which was then thermoformed into the shape shown in FIGS. 2 and 3 to form a core material. Vibration 8i was created by pasting aluminum foil with a thickness of 50 μm as a surface material on both sides of this core material using a gvA hot melt adhesive. When the obtained diaphragm was assembled into a speaker in the same manner as in the conventional example, the sound pressure frequency characteristics were measured and are shown in FIG. 4a. For comparison, the characteristics of the conventional example are shown in Figure b61. 1 Frequency characteristics are 1m in JIS standard box
/1W.

From the results shown in FIG. 4, it can be seen that according to this example, the speaker is more efficient than that using an aluminum honeycomb. This is because a lightweight, high-density material is used in which light 4-methylpentene fibers are used as a binder with light carbon fibers, so a thinner material is required to obtain the same characteristics.

Table 1 shows a comparison of the physical properties of the materials of the examples and aluminum.

Table 1 (*Constant weight) 7... As shown in Table 1, according to this example, the bending rigidity, which is an important physical property of the core material of a structure, is significantly improved at the same weight. .

Although carbon fiber was used here as a reinforcing material for the core material, other high elastic fibers (aramid fiber, etc.) were used.

Glass fiber, etc. with a Young's modulus of 1×1 odyn/- or more)
Similar effects can be obtained by using .

These composite materials have a relatively large internal loss compared to aluminum, and contribute to a considerable reduction in sound pressure peaks.

The biggest advantage of using a plastic composite material for the core material is that it can be molded in one piece in a short time, so it can be produced in about 1,720 man-hours compared to conventional aluminum honeycomb, and is inexpensive and the quality is much more stable. Effects of the Invention As detailed above, according to the present invention, a composite sheet of carbon fiber and 4-methylpentene is used as the core material of a diaphragm having a sandwich structure, and at least three fan-shaped small pieces having parallel lips are used. that's all.

Since they are assembled to form a circular core material and the surface material is adhered to both sides of the core material, it is lightweight and can be produced at an extremely low cost by integral thermoforming without the need for complicated processes as in the past. Moreover, the nodal circle is close to the outline, so it can be used in exactly the same way as a conventional flat plate speaker. Since the core material is made of plastic fiber with internal loss, the high-frequency resonance peak level is small and system design is easy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a speaker unit using the flat speaker diaphragm of the present invention, FIG. 2 is an enlarged plan view showing the core of the flat diaphragm, and FIG. 3 is a line AA' line thereof. A cross-sectional view of FIG. 4 is a comparative characteristic diagram of sound pressure frequency characteristics according to an embodiment of the present invention and a conventional example. 1...Heartwood, 2...Small pieces-3...
...Flat diaphragm.

Claims (2)

[Claims] (1) Synthetic fibers made of 4-methylpentene polymer are used as a base material, and carbon fibers and aramid fibers are added thereto. 6 to 40% (
A diaphragm for a speaker, characterized in that a surface material is bonded to both sides of a core material obtained by thermoforming sheet la obtained by mixing (weight ratio) and paper-making. (2) The speaker according to claim 1, wherein the core material is formed into a circular shape by assembling at least three fan-shaped small pieces having a plurality of ribs arranged at angles that do not converge. diaphragm.