JPS6343496A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To improve an acoustic characteristic by using materials obtained by mixing materials that a kraft pulp and a chitin, which is a natural high molecular, are graft polymerized with polyvinyl alcohol as a diaphragm for speaker. CONSTITUTION:The chitin(120 mesh paths of powder), a natural high molecular, is graft polymerized with the polyvinyl alcohol whose polymerizing degree is one thousand to obtain the material. The above-mentioned material and the kraft pulp are mixed at the rate of 3:7 in the weight rate. Next, the diaphragm 4 in a dome shape is formed by making paper with a cylinder mold system. At the corner of the diaphragm 4 the tip of a voice coil bobbin 5 coiled with voice coil 6 is fixed. Thus the occurence of both alternative and split of the diaphragm is prevented and a distortion rate is made small. And also the frequency expanding to a high pass is obtained and an acoustic output is made large.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a speaker diaphragm used in acoustic output equipment and the like.

Conventional technology In recent years, in the cassette tape recorder, micro cassette tape recorder, and high-fidelity stereo industries, there has been a demand for speakers with better output sound pressure, distortion rate, and flatness than before in terms of the acoustic characteristics of speakers used as audio output equipment. Speaker diaphragms, which influence acoustic characteristics, are becoming increasingly important.

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

FIG. 2 shows a cross-sectional view of the vibration system of a conventional speaker. In FIG. 2, 1 is a diaphragm, 2 is a voice coil bobbin fixed to the entire tip 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 consists of a vibration system including a diaphragm 1, a voice coil bobbin 2, a voice coil 3, and a magnetic circuit system (not shown) including a magnet, a ball, a plate, and a yoke. When an audio current flows through the voice coil 3 in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil 3, causing it to vibrate in accordance with the current. This vibration is properly transmitted to the vibration of the diaphragm 1 and radiated as a sound wave (for example, Hisao Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

Problems to be Solved by the Invention However, it is ideal that the diaphragm of a speaker makes piston motion over the frequency band used, but if the diaphragm deforms during vibration or split vibration occurs, the sound pressure -
Frequency characteristics, distortion rate, phase characteristics, etc. deteriorate, which impedes high-fidelity reproduction. In addition, conventional paper cone diaphragms and plastic imaging plates have E/ρ (however, E:
Because the modulus of elasticity (ρ: density) is small, the high-frequency resonant frequency is low, and the speaker has the disadvantage that it cannot reproduce high frequencies. -O In view of the above-mentioned problems, the present invention provides a complete speaker diaphragm having a high high-frequency resonant frequency, rather than a Q-split oscillating metal whose diaphragm is deformed during vibration.

Means for Solving the Problems In order to achieve this object, the speaker imaging plate of the present invention is a diaphragm made of a material made of a mixture of kraft pulp and chitin, a natural polymer, graft polymerized with polyvinyl alcohol. It was used as

Function - In the present invention, this sheet-like material is made by mixing chitin, which is a natural polymer material with a high elastic modulus, and polyvinyl alcohol, which has a high mechanical internal loss and is graft-polymerized with chitin, into full kraft pulp. Because it is configured,
Due to the effect of chitin, the bending rigidity of the υ diaphragm is extremely high, and the diaphragm does not deform or split resonance occurs during vibration. In addition, due to the effect of polyvinyl alcohol grafted onto chitin, the mechanical internal loss is increased, so there is less fray in frequency characteristics, and the speaker has excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics. Obtainable. ! In addition, since this diaphragm material is made of polyvinyl alcohol that has been graft-polymerized with chitin, it has a high affinity with kraft pulp, which has all of the same hydroxyl groups, so it has good binding properties with kraft pulp and can produce strong paper.

Furthermore, since polyvinyl alcohol graft-polymerized onto chitin is hydrophilic, there is no fear that it will separate from water during papermaking.

Example Below, regarding a speaker diaphragm according to an example of the present invention,
This will be explained with reference to the drawings.

FIG. 1 shows a sectional view of a speaker in one embodiment of the present invention. In Figure 1, 4 is a diaphragm molded from a mixture of kraft pulp and chitin, a natural polymer, 6 is a voice coil bobbin whose tip is fixed to the diaphragm 4, and 6 is a magnetic gap in the magnetic circuit (not shown). This is a voice coil that is inserted into the

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

As shown in FIG. 1, the speaker consists of a vibration system such as a diaphragm 4, a voice coil bobbin 6, and a voice coil 6, and a magnetic circuit system (not shown) consisting of a magnet, a ball, a plate, and a yoke. When an audio current flows through the voice coil 6 in a uniform magnetic field, an electromagnetic force in the vertical direction is generated in the voice coil 6, and the voice coil 6 vibrates in accordance with the current. The total pressure of this vibration is transmitted to the vibration of the diaphragm 4 and emitted as a sound wave.

Next, the manufacturing method of the diaphragm 4 will be described. A material obtained by graft polymerizing polyvinyl coal with a degree of polymerization of 1000 to chitin, a natural polymer (in powder form, 120 mesh pass), and kraft pulp in a weight ratio. Mix at a ratio of 3. Then, the paper is made using the round net method, and the diameter of the paper is 2.
It has a dome-shaped diaphragm with a fabric weight of 30g/vf.

As described above, according to this embodiment, the speaker uses the entire diaphragm 4 molded from a mixture of kraft pulp and a material obtained by graft-polymerizing polyvinyl alcohol to chitin, a natural polymer. Good acoustic characteristics are obtained without split resonance, and the distortion rate is lower than that of an aluminum dome-shaped imaging plate of the same shape! ! -30dB reduction is possible.

Also, the high resonant frequency is 21 KHz to 30 KHz.
Hz. Furthermore, the peak dip of the output sound pressure can be reduced by approximately ±3 dB, which is ±3 dB compared to an aluminum diaphragm.

Effects of the Invention As described above, the present invention uses, as a diaphragm, a molded product made entirely of a mixture of kraft pulp and chitin, which is a natural polymer, and polyvinyl alcohol completely graft-polymerized.
It is possible to obtain a speaker with a low distortion rate, a high high-frequency resonance frequency, and a large acoustic output, and it is possible to realize an excellent speaker with good acoustic characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an imaging system for a speaker diaphragm according to an embodiment of the invention, and FIG. 2 is a sectional view of a conventional speaker imaging system. 4...Diaphragm, 5...Voice coil bobbin, 6...Whistle coil. Name of proxy: Toshio Nakao and 1 other person
1 Figure 6---Voice coil? ---Voice coil bobbin

Claims (1)

[Claims] A speaker diaphragm characterized by using a material made from a mixture of kraft pulp and a material obtained by graft polymerizing chitin, a natural polymer, with polyvinyl alcohol.