JPH01220598A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a speaker having a low distortion rate, a high-band resonance frequency, and a large output by using a diaphragm consisting of a material where kraft pulp and whiskers, which consists of a zinc oxide whose crystal is grown from the center in four different directions, are mixed. CONSTITUTION:With respect to production of the diaphragm, kraft pulp, whiskers consisting of a zinc oxide whose crystal is grown from the center in four different directions, and an epoxy binder are mixed in 7:2:1 by weight and are formed to a domic diaphragm having 28mm diameter and 30g/m<2> bulk density by paper making in the cylinder machine system. A speaker using the diaphragm where kraft pulp and whiskers consisting of the zinc oxide whose crystal is grown from the center in four different directions are mixed is free from diaphragm deformation and split resonance to obtain satisfactory acoustic characteristics.

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.

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, voice coil bobbin, and voice coil, and a magnetic circuit system consisting of a magnet, pole, plate, and yoke.

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

Problems to be Solved by the Invention However, ideally, the diaphragm 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, impeding high-fidelity reproduction. In addition, because the E/p (E: elastic modulus, p: density) of the diaphragm material of conventional Gion cone diaphragms and plastic diaphragms is small, the high-frequency resonance frequency is low.
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 Problem In order to achieve this object, the speaker diaphragm of the present invention is made of a material in which a kraft bulb and whiskers with a high elastic modulus made of zinc oxide with crystals grown in four different directions from the center are mixed. 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, causing deformation of the diaphragm during vibration and split resonance. In addition, since Kraft valve is used as the base material and whiskers with a high elastic modulus made of zinc oxide with crystals grown in four different directions from the center are used, the specific elastic modulus and E /p (However, E
: elastic modulus, ρ: high density. When 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 can be obtained.

In addition, this diaphragm material is made of a material mixed with whiskers made of zinc oxide with crystals grown in four different directions from the center of the kraft valve, so that the kraft valve and the whiskers are well intertwined with each other, unlike the traditional needle-like shape. The modulus of elasticity can be increased compared to whiskers.

Furthermore, since this diaphragm material uses a material whose main component is kraft valve, it can be manufactured using conventional papermaking methods, making it extremely suitable for mass production.

EXAMPLE A speaker diaphragm according to an example of the present invention will be described below.

A speaker according to an embodiment of the present invention uses, as a diaphragm, a material in which a kraft bulb and whiskers made of zinc oxide, in which crystals are grown in four different directions from the center, are mixed. 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, voice coil bobbin, and voice coil, and a magnetic circuit system consisting of a magnet, pole, plate, and yoke. - When an audio current flows through a voice coil located in a 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, we will talk about the manufacturing method of the diaphragm. A kraft valve, whiskers made of zinc oxide with crystals grown in four different directions from the center (in powder form, 300 mesh pass), and an epoxy binder are mixed in a weight ratio of "l: The mixture was mixed at a ratio of 2:1 and paper was made using a circular net method to form a dome-shaped diaphragm with a diameter of 28 tsuru and a basis weight of 30 g/-.

As described above, according to this example, a speaker using a diaphragm mixed with whiskers made of zinc oxide with crystals grown in four different directions from the center of the Kraft valve is good without deformation of the diaphragm or split resonance. It has excellent acoustic characteristics, and the distortion rate can be reduced by 25 dB compared to an aluminum dome-shaped diaphragm of the same shape. Furthermore, the high resonance frequency was able to be raised from 21 kHz to 39 kHz.

Furthermore, the peak dip of the output sound pressure can also be reduced by about ±3 dB, which is ±3 dB compared to an aluminum diaphragm.

Furthermore, when comparing the characteristics of a diaphragm using conventional needle-shaped whiskers, an improvement of 3 dB in distortion rate and an improvement of 4 kHz in high-frequency resonance frequency was observed.

Effects of the Invention As described above, the present invention uses, as a diaphragm, a material mixed with whiskers made of zinc oxide with crystals grown in four different directions from the center of the Kraft valve, which has a low distortion rate and high-frequency resonance. A speaker with a high frequency and a large acoustic output can be obtained, and an excellent speaker with good acoustic characteristics can be realized.

Claims (1)

[Claims] A speaker diaphragm characterized by using a material containing a mixture of kraft pulp and whiskers made of zinc oxide in which crystals grow in four different directions from the center.