JPH07112310B2 - Speaker diaphragm - 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 that is more excellent in output sound pressure, distortion rate, and flatness than before is desired. Therefore, speaker diaphragms, which influence the acoustic characteristics, are 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 characteristics, The distortion rate, 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, a speaker diaphragm of the present invention is made of a material obtained by mixing whiskers having a large elastic modulus, which are made of kraft pulp and zinc oxide having crystals grown in four different directions from the center. It was used as a diaphragm.

Effect The present invention has a very large elastic modulus due to the above-mentioned configuration, and when this is used as a diaphragm, the bending rigidity of the diaphragm becomes very large, and the diaphragm is deformed or split resonance occurs during vibration. Absent. In addition, since kraft pulp is used as the base material and a whisker with a large elastic modulus made of zinc oxide in which crystals grow in four different directions from the above center is mixed and used, the specific elastic modulus, E / ρ (However, E:
The 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 having excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics can be obtained.

In addition, since this diaphragm material is a material in which whiskers made of kraft pulp and zinc oxide in which crystals have grown in four different directions from the center are mixed and used, the entanglement between kraft pulp and whiskers is good, and the conventional needle-shaped material is used. The elastic modulus can be increased as compared with whiskers.

Further, since this diaphragm material is made of a material containing kraft pulp as a main component, it can be manufactured by a conventional papermaking method, so that it is very excellent in mass productivity.

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 material obtained by mixing whiskers made of kraft pulp and zinc oxide in which crystals grow in four different directions from the center. 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 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 is emitted as a sound wave.

Next, the method of manufacturing the diaphragm will be described. The weight ratio of the whiskers (powdered, 300 mesh pass) made of kraft pulp and zinc oxide with crystals grown in four different directions from the center and the epoxy binder in a weight ratio of 7: Mixed at a ratio of 2: 1 and made into paper by the gauze method, with a diameter of 28 mm and basis weight
A 30 g / m ² dome-shaped diaphragm was used.

As described above, according to this embodiment, the speaker using the diaphragm mixed with kraft pulp and the whiskers made of zinc oxide having crystals grown in four different directions from the center is good without deformation of the diaphragm or split resonance. The acoustic characteristics are excellent, and the distortion rate can be reduced by 25 dB compared to the aluminum dome type diaphragm of the same shape. Moreover, the high frequency resonance frequency could be increased from 21kHz to 39kHz. 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.

Moreover, in the comparison of the characteristics of the diaphragm using the conventional needle-shaped whiskers, the distortion rate was improved by 3 dB and the high resonance frequency was improved by 4 kHz.

EFFECTS OF THE INVENTION As described above, the present invention uses as a diaphragm a material obtained by mixing whiskers made of kraft pulp and zinc oxide in which crystals grow in four different directions from the center. A speaker having a high frequency and a large acoustic output can be obtained, and an excellent speaker having good acoustic characteristics can be realized.

Claims (1)

[Claims] 1. A diaphragm for a speaker, comprising: a kraft pulp and a material in which whiskers made of zinc oxide having crystals grown in four different directions from the center are mixed.