JPS63287297A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a speaker with less distortion factor, large high resonance frequency and sound output by using a molding with a mixture of urushiol and novolak coated onto both faces of a pulp raw material as a diaphragm. CONSTITUTION:The molding of the pulp raw material on both faces of which a mixture of urushiol and novolak being a phenol derivative is coated is used as a diaphragm. In this case, the bending rigidity of the diaphragm is very large and neither deformation of the diaphragm nor split resonance in caused during vibration. Moreover, craft pulp is used as a base material and the molding of the pulp raw material on both faces of which a mixture of urushiol and novolak is coated being a phenol derivative is used, then the specific elasticity is large, the reproducing band of the speaker is extended and the speaker with excellent sound pressure-frequency characteristic, distortion factor and phase characteristic is obtained.

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 hi-fi stereo industries, speakers as sound output equipment are becoming increasingly popular in terms of their acoustic characteristics. Speaker diaphragms, which are highly desired and have an influence on acoustic characteristics, are becoming more and more important.

The operation of the above-mentioned example of the conventional speaker will be described below. A speaker consists of a vibration system such as a diaphragm, a voice coil bobbin, and a voice coil, and a magnetic circuit system that includes a magnet, a ball, a plate, and a yoke.

When an audio current flows through a voice coil that is placed in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil, causing it to vibrate in response to the current. This vibration is properly transmitted to the vibration of the diaphragm and emitted as a sound wave (for example, Hisao Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

However, ideally, the receding plate of a speaker should make a piston movement 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 diaphragms have a low high-frequency resonance frequency because the reciprocating plate material has a small E/ρ (E: elastic modulus, ρ: density).
The drawback was that the speakers could not reproduce high frequencies.

In view of the above-mentioned problems, the present invention provides a diaphragm for a speaker that does not deform or cause split vibration during vibration and has a high high resonance frequency.

Means for Solving the Problems In order to achieve this object, the speaker diaphragm of the present invention vibrates a molded product in which a mixture of urushiol, which is one of the phenol derivatives, and novolac is applied to both sides of a pulp material. It was used as a board.

Function The present invention has a very large elastic modulus due to the above-mentioned configuration, and when used as a diaphragm, the diaphragm has a very large bending rigidity, and the diaphragm deforms during vibration and split resonance occurs. do not have. However, since we are using kraft pulp as a base material and a molded product with a mixture of urushiol, one of the phenol derivatives mentioned above, and novolak applied to both sides of the pulp material, the specific elastic modulus E/ρ (however,
E: modulus of elasticity, ρ: density) is very high, and when used as a diaphragm, the reproduction band of the speaker is extended and the sound pressure is excellent.
A speaker with good frequency characteristics, distortion rate, and phase characteristics can be obtained.

However, since this diaphragm material uses a molded product coated on both sides of pulp material with a mixture of urushiol, a phenol derivative, and novolak, it has excellent solvent resistance and
Excellent heat resistance. However, since it contains novolak, which has excellent water resistance, it can withstand the use of speakers under extremely harsh conditions.

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

explain about.

A speaker according to an embodiment of the present invention uses a molded product made of a pulp material coated on both sides with a mixture of urushiol, which is one of the phenol derivatives, and novolac, as a diaphragm. This diaphragm is fixed to a voice coil bobbin, and the voice coil provided at the tip of the voice coil bobbin is inserted into a magnetic gap of a magnetic circuit.

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

A speaker consists of a vibration system such as a diaphragm, a voice coil bobbin, and a voice coil, and a magnetic circuit system consisting of a magnet, a ball, a plate, and a yoke. When an audio current flows through a voice coil in a uniform magnetic field, a vertical electromagnetic force is generated in the voice coil, causing it to vibrate in response to the current. This vibration is properly transmitted to the vibration of the diaphragm and emitted as a sound wave.

Next, the method for manufacturing the diaphragm is described: - A mixture of 9 parts of urushiol, which is a phenol derivative, and 10 parts of novolac is applied to both sides of kraft pulp with a basis weight of 26 g/d to a thickness of 60 microns, and the temperature is 100°C. , pressure 10
Cured and molded under the conditions of kg/(y, time 10m1n), φ3
It has a dome-shaped diaphragm of 0111fl.

As described above, according to this embodiment, a speaker using a diaphragm with a mixture of urushiol, which is one of the phenol derivatives, and novolak applied to both sides of the pulp material,
Good acoustic characteristics are obtained without deformation of the diaphragm or split resonance, and the distortion rate can be reduced by 22 dB compared to an aluminum dome-shaped diaphragm of the same shape. Also,
The high resonance frequency was able to be raised to 21 (36K) from 2) to 12. Also, the peak dip of the output sound pressure is ±adB, which is about ±sd compared to the aluminum 9mm diaphragm.
B can be lowered.

In addition, in material reliability tests, we measured the deterioration of the flexural modulus after leaving the specimen for 500 hours at a temperature of 65" C5 and a humidity of 98% RH. As a result, the specimen coated with urushiol The specimen coated with the urushiol and novolak mixture of the present invention showed only 2% deterioration, compared to 10% deterioration.

Effects of the Invention As described above, the present invention uses a molded product in which a mixture of urushiol, which is one of the phenol derivatives, and novolak is coated on both sides of a pulp material as a diaphragm.
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.

Claims (1)

[Claims] A speaker diaphragm characterized by using a molded product in which a mixture of urushiol, which is one of the phenol derivatives, and novolak is applied to both sides of a pulp material.