JPH07112308B2 - Vibration plate for speakers - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm for a speaker used in an acoustic output device or the like.

2. Description of the Related Art In recent years, cassette tape recorders, microcassette tape recorders, and high-fidelity stereo industries are demanded to have a speaker that is more excellent in output sound pressure, distortion, and flatness than the conventional acoustic characteristics of a speaker as an acoustic output device. Therefore, speaker diaphragms, which influence the acoustic characteristics, are becoming more and more important. The operation of the above-described conventional speaker will be described below. The speaker consists of a vibration system such as a diaphragm and voice coil, and a magnetic circuit system consisting of a magnet, pole, plate, and yoke. When a voice current flows through a voice coil in a uniform magnetic field, a vertical driving force is generated in the voice coil and vibrates according to the current. This vibration is correctly transmitted to the vibration of the diaphragm and emitted as a sound wave (for example, Toshio Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

Problems to be Solved by the Invention However, it is ideal that the diaphragm of the speaker makes a piston movement over the frequency band used, but if the diaphragm is deformed or divided vibration occurs during vibration, the sound pressure-frequency characteristics and distortion are generated. The rate, phase characteristics, etc. are deteriorated, which hinders high fidelity reproduction. Also, conventional paper cone diaphragms and plastic diaphragms have a low E / ρ (E: elastic modulus, ρ: density) of the diaphragm material, so the high resonance frequency is low and the speaker cannot reproduce up to high frequencies. There is a drawback that.

In view of the above problems, the present invention provides a speaker diaphragm having a high high-frequency reproduction frequency, which does not cause deformation of the diaphragm during vibration or divisional vibration.

Means for Solving the Problems In order to achieve this object, a speaker diaphragm of the present invention comprises a kraft pulp, a natural polymer, chitin having deacetylated chitin, a polyamide epichlorohydrin resin, and a flaky shape. It is composed of a structure in which mica and polyvinyl alcohol fibers are mixed and made into paper and heated to cause reactive foaming.

Action The present invention has the above-mentioned constitution, and is a natural polymer material having a large elastic modulus, chitosan and kraft pulp, and the above-mentioned 2
Polyamide epichlorohydrin resin for cross-linking various kinds of materials with epoxy groups is mixed and heated, and unlike conventional paper pulp, not only the entanglement of the fibers but also the chemical partial bonding of the fibers. Therefore, the strength is large, and since flake shaped mica is mixed as a reinforcing material, the grouping ratio is very large, and the internal loss is large due to slippage between fibers and between mica layers, which has ideal physical properties. The vibrating plate can be realized. Further, in the constitution of the present invention, since the polyvinyl alcohol fiber is made into a binder by being made into a paper and heated to be a porous body foamed by the vapor pressure of water, it is possible to increase the thickness even with the same weight to form a vibration plate. Therefore, the bending rigidity is increased, and the diaphragm is not deformed during vibration or split resonance does not occur.

Example Hereinafter, a speaker diaphragm according to an example of the present invention will be described.

In one embodiment of the present invention, the speaker is a mixed polymer of kraft pulp, natural polymer chitin, deacetylated chitosan, epoxy-containing polyamide epichlorohydrin resin, flaky mica, and polyvinyl alcohol fiber. The vibrating plate is a structure that is heated and reactively foamed. This diaphragm is fixed to the voice coil bobbin, and the voice coil provided at the tip of the voice coil bobbin is inserted in the magnetic gap of the magnetic circuit.

The operation of the speaker configured as above will be described below. The speaker is composed of a vibration circuit such as a diaphragm and a voice coil, and a magnetic circuit system including a magnet, a pole, a plate, and a yoke. When a voice current flows through the voice coil in a uniform magnetic field, a vertical driving force is generated in the voice coil and vibrates according to the current. This vibration is correctly transmitted to the diaphragm and is emitted as a sound wave.

Next, a method of manufacturing the diaphragm will be described. Kraft pulp fiber (fiber length 2 to 3 mm), chitosan, polyamide epichlorohydrin resin, 400 mesh pass flake shaped mica, and polyvinyl alcohol fiber (fiber length 3 mm to 10 mm)
Was mixed at a weight ratio of 14: 3: 3: 60: 20, and then water was added to disperse and stir to make a 3% solution. After papermaking with a paper machine, heat to 120 ° C in the vibration plate molding and foam. Apparent density, 0.1
A diaphragm of g / cm ³ was used.

As described above, according to the present embodiment, since chitosan and kraft pulp are cross-linked by the epoxy group and bonded to each other, the fiber is stronger than the entanglement of fibers such as that of conventional paper pulp, and the scale-like shape. Since it is reinforced by mica and made porous to make it thicker and can be used as a diaphragm, it has a very large bending rigidity, and it is difficult for the diaphragm to deform and good splitting resonance does not occur and good acoustic characteristics are obtained. is there. The same effect can be obtained regardless of whether the diaphragm shape is a dome shape or a cone shape, and even when it is used as a core material of a flat plate diaphragm having a sandwich structure, it has good bending rigidity and good characteristics.

Furthermore, in this example, the mixing ratio of pulp, chitosan, polyamide epichlorohydrin resin, mica and polyvinyl alcohol fiber was 14: 3: 3: 60: 20, but it can be freely changed according to the required physical properties of the diaphragm. For example, it is possible to increase the expansion ratio by increasing the polyvinyl alcohol fiber and increase the elastic modulus by increasing the mica.

Effects of the Invention As described above, the present invention is a vibrating plate made of a porous body obtained by heat-foaming after mixing papermaking of kraft pulp, chitosan, polyamide epichlorohydrin resin, scaly mica and polyvinyl alcohol fiber, and chitosan. The kraft pulp and the kraft pulp are partially chemically bonded by the epoxy group, and the strength is higher than the entanglement of fibers of conventional paper pulp, and the elastic modulus is very large because the flaky mica is mixed as a reinforcing material. . In addition, since polyvinyl alcohol fibers are used as a binder for foaming with water vapor, it becomes porous and the apparent density can be reduced,
When the diaphragm is used, there is an advantage that the bending rigidity can be increased by increasing the thickness with the same weight. Further, slippage between fibers or between layers of scaly mica can increase the internal loss, thus reducing distortion and realizing an excellent speaker having good acoustic characteristics with a high resonance frequency.

Claims (1)

[Claims] 1. A kraft pulp, chitosan in which a natural polymer chitin is deacetylated, a polyamide epichlorohydrin resin, flaky mica, and polyvinyl alcohol fiber are mixed and paper-formed, and heated and reactively foamed. A speaker diaphragm consisting of a structure.