JPH0695799B2 - 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 in the hi-fi stereo industry, speakers with excellent output sound pressure, distortion rate, and flatness have been desired even in the acoustic characteristics of speakers as acoustic output devices. The diaphragm for speakers, which influences the acoustic characteristics, is becoming more and more important.

An example of the above-described conventional speaker will be described below with reference to the drawings.

FIG. 2 shows a sectional view of a vibration system of a conventional speaker. In FIG. 2, 1 is a diaphragm, 2 is a voice coil bobbin whose tip is fixed to the diaphragm 1, and 3 is a voice coil inserted into a magnetic gap (not shown) of a magnetic circuit.

The operation of the speaker configured as above will be described below. As shown in FIG. 2, the speaker includes a vibration system such as a diaphragm 1, a voice coil bobbin 2, and a voice coil 3 and a magnetic circuit system (not shown) including a magnet, a pole, a plate, and a yoke. When a voice current flows through the voice coil 3 in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil 3 and vibrates according to the current. This vibration is correctly transmitted to the vibration of the diaphragm 1 and emitted as a sound wave (for example, Toshio Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

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

In view of the above problems, the present invention provides a speaker diaphragm having a high high resonance frequency, which does not cause the diaphragm to deform or generate divided vibration during vibration.

Means for Solving the Problems To achieve this object, the speaker diaphragm of the present invention uses a material obtained by mixing a material obtained by graft-polymerizing kraft pulp and chitin, which is a natural polymer, with polyvinyl alcohol as a diaphragm. Used.

Effect The present invention comprises a sheet-shaped material obtained by mixing kraft pulp with a material comprising chitin, which is a natural polymer material having a large elastic modulus, and polyvinyl alcohol having a large mechanical internal loss graft-polymerized to the chitin. Because
Due to the chicken-like effect, the flexural rigidity of the diaphragm is very large, and the diaphragm is not deformed during vibration or split resonance does not occur.
Also, due to the effect of polyvinyl alcohol graft-polymerized on chitin, the mechanical internal loss becomes large,
It is possible to obtain a speaker having excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics with few irregularities in frequency characteristics. Further, since this vibrating plate material is a polyvinyl alcohol graft-polymerized in chitin, it has a high affinity with kraft pulp having the same hydroxyl group, and therefore a paper having good binding property with kraft pulp and strong can be produced.

In addition, since polyvinyl alcohol graft-polymerized on chitin is hydrophilic, there is no fear of separation from water during papermaking.

Example Hereinafter, regarding the speaker diaphragm of one example of the present invention,
A description will be given with reference to the drawings.

FIG. 1 is a sectional view of a speaker according to an embodiment of the present invention. In FIG. 1, 4 is a vibration plate formed by mixing kraft pulp and chitin, which is a natural polymer, and molded, 5 is a voice coil bobbin whose tip is fixed to the vibration plate 4, and 6 is a magnetic gap of a magnetic circuit (not shown). It is a voice coil that is inserted in ().

The operation of the speaker configured as above will be described below.

As shown in FIG. 1, the speaker includes a vibration system such as a diaphragm 4, a voice coil bobbin 5, and a voice coil 6 and a magnetic circuit system (not shown) including a magnet, a pole, a plate, and a yoke. When a voice current flows through the voice coil 6 in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil 6 and vibrates in accordance with the current. This vibration is correctly transmitted to the vibration of the diaphragm 4 and is emitted as a sound wave.

Next, the manufacturing method of the vibration plate 4 will be described. Chitin which is a natural polymer (powdered, 120 mesh pass)
A material obtained by graft-polymerizing polyvinyl coal having a degree of polymerization of 1000 and kraft pulp are mixed in a weight ratio of 3: 7. Then, a dome-shaped vibrating plate with a diameter of 28 mm and a basis weight of 30 g / m ² is produced by the circular net method.

As described above, according to the present embodiment, the speaker using the diaphragm 4 formed by mixing the kraft pulp and the material obtained by graft-polymerizing polyvinyl alcohol to chitin which is a natural polymer is Good acoustic characteristics can be obtained without split resonance, and the distortion rate can be reduced by 30 dB compared to the aluminum dome type diaphragm of the same shape. In addition, the high resonance frequency can be increased from 21 KHz to 30 KHz. Also, the peak dip of the output sound pressure is ±
Compared to 3dB and aluminum diaphragm, it can be reduced by about ± 3dB.

Effects of the Invention As described above, the present invention uses a molded product obtained by mixing materials made by graft-polymerizing polyvinyl alcohol to kraft pulp and natural polymer chitin, as a vibration plate,
It is possible to obtain a speaker having a low distortion rate, a high resonance frequency and a high acoustic output, and an excellent speaker having good acoustic characteristics can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a vibration system of a speaker diaphragm according to an embodiment of the present invention, and FIG. 2 is a sectional view of a vibration system of a conventional speaker. 4 ... Vibration plate, 5 ... Voice coil bobbin, 6 ... Voice coil.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Saeki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Tsuneo Tanaka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A speaker diaphragm, comprising a material obtained by mixing a material obtained by graft-polymerizing kraft pulp and a chitin which is a natural polymer with polyvinyl alcohol.