JPH07110079B2 - 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, in terms of the acoustic characteristics of the speaker as an acoustic output device, a speaker with better output sound pressure, distortion, and flatness than before is desired. The diaphragm for speakers, which influences the acoustic characteristics, is becoming more and more important.

The operation of the above-mentioned conventional speaker will be described below. The speaker includes a vibration system such as a diaphragm, a voice coil bobbin, 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 a voice coil in a uniform magnetic field, a vertical electromagnetic 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).

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 during vibration or divided vibration occurs, the sound pressure-frequency characteristic , Distortion, phase characteristics, etc. are deteriorated, which hinders high-fidelity reproduction. Also, conventional paper cone diaphragms and plastic diaphragms have E / ρ (where E: elastic modulus,
Since ρ: density) is small, there is a drawback that the high frequency resonance frequency is low and the speaker cannot reproduce up to the high frequency range.

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 In order to achieve this object, the speaker diaphragm of the present invention uses a molded product obtained by heating and curing a mixture of urushiol, which is one of the phenol derivatives, and natural mica as the diaphragm. It was what I had.

Action The present invention has a very large elastic modulus due to the above configuration, and when this is used as a diaphragm, the bending rigidity of the diaphragm is very large, and the diaphragm is not deformed during vibration or split resonance does not occur. . In addition, since natural mica with a very high elastic modulus is used as the material and a molded product obtained by mixing this with urushiol, which is one of the above-mentioned phenol derivatives, and heating and curing is used, the specific elastic modulus E / ρ (However, E: elastic modulus, ρ: density) is large, and when this is used as a diaphragm, the reproduction band of the speaker is extended and a speaker with excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics is obtained. You can

Further, since Urushiol has a very large internal loss, when this is used as a diaphragm, the peaks and valleys of the sound pressure-frequency characteristics of the speaker can be flattened and faithful sound reproduction can be obtained.

Further, this diaphragm material is excellent in solvent resistance and heat resistance because it uses a molded product obtained by heating and curing a mixture of urushiol, which is one of the phenol derivatives, and natural mica. In addition, the weakness of the Urushiol, which is slightly weak in water resistance, is compounded with natural mica, which has excellent water resistance, so it can withstand use of the speaker under extremely severe conditions.

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

The speaker in one embodiment of the present invention uses as a diaphragm a molded product obtained by heating and curing a mixture of urushiol, which is one of the phenol derivatives, and natural mica. This diaphragm is fixed to a voice coil bobbin, and a bobbin 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 consists of a vibration system such as a diaphragm, voice coil bobbin, and voice coil, and a magnetic circuit system consisting of a magnet, pole, plate, and yoke. When a voice current flows in a uniform magnetic field, the voice coil moves up and down. Directional electromagnetic force is generated and vibrates according to the current. This vibration is correctly transmitted to the vibration of the diaphragm and is emitted as a sound wave.

Next, the method of manufacturing the diaphragm will be described. A mixture of 90 parts of urushiol, which is a phenol derivative, and 10 parts of natural mica (phlogopite mica 150 mesh pass) was heated at a temperature of 100.
Φ3 at the temperature of 20kg / cm ² for 30min.
It is a 0 mm dome-shaped diaphragm.

As described above, according to the present embodiment, the speaker using the molded product obtained by heating and curing the mixture of urushiol, which is one of the phenol derivatives, and natural mica as the diaphragm,
Good acoustic characteristics can be obtained without the deformation and split resonance of the diaphragm, and the distortion rate can be reduced by 20 dB compared with the aluminum dome diaphragm of the same shape. Moreover, the high frequency resonance frequency could be raised from 21kHz to 32kHz.
Moreover, the peak dip of the output sound pressure can be reduced by ± 3 dB, which is about ± 3 dB lower than that of the aluminum diaphragm.

In the material reliability test, the temperature was 55 ° C and the humidity was 98.
After leaving the test piece for 500 hours under the condition of% RH, the deterioration of the flexural modulus was measured. As a result, the test piece coated with only urushiol showed a deterioration of 10%, while the present invention is obtained. Specimens coated with the mixture of urushiol and novolac had a deterioration of 0.1%.

Effects of the Invention As described above, the present invention uses a molded product obtained by heating and curing a mixture of urushiol, which is one of the phenol derivatives, and natural mica as a vibration plate, and has a small strain rate,
It is possible to obtain a speaker having a high high resonance frequency and a large acoustic output, and to realize an excellent speaker having good acoustic characteristics.

Claims (1)

[Claims] 1. A diaphragm for a speaker, comprising a molded product obtained by heating and curing a mixture of urushiol, which is one of phenol derivatives, and natural mica.