JP3161895B2 - Electroacoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm and an electroacoustic transducer using the diaphragm.

[0002]

2. Description of the Related Art Many materials have been conventionally developed as diaphragm materials for, for example, electrodynamic loudspeakers generally used in conventional audio equipment and the like. The typical physical properties of a diaphragm made of the following materials are: density: 0.485; Young's modulus: 1.17 × 10 ¹⁰ dyn / cm ² ;
0714.

[0003] Generally, the diaphragm of such a speaker is
(1) low density, (2) high rigidity,
(3) An ideal condition is that the internal loss is large. To obtain such a condition, conventionally, a diaphragm material incorporating a highly rigid substance such as carbon fiber or aramid fiber, polypropylene, or the like is used. A diaphragm material having a large internal loss, such as, for example, has been developed.

[0004]

By the way, when trying to increase the rigidity of the diaphragm, the internal loss is reduced,
If the density increases, or if an attempt is made to obtain a large internal loss, the rigidity tends to decrease and the density tends to increase.

[0005] Therefore, it is an important task to make the diaphragm (cone paper) of the speaker to balance the above elements (1) to (3) in a high order.

For example, in the case of aluminum material, the density is 2.7,
The Young's modulus is 62 × 10 ¹⁰ dyn / cm ² , the internal loss is 0.002, and in the case of polypropylene, the density is 0.
91, Young's modulus is 1.08 × 10 ¹⁰ dyn / cm ² , and internal loss is 0.07.

Further, in the case of a diaphragm made of wood pulp, although the internal loss is moderately large and the density is small, there is a problem that the frequency band is narrow due to insufficient rigidity. In order to restore the forest to the place after logging,
There is a problem that a large amount of cost and a long time are required, and it is difficult to obtain high-quality pulp at present.

Further, when making a diaphragm from wood pulp,
The wood pulp must be beaten over a long period of time (hitting the wood pulp in water) in order to make the fibers of the wood pulp tangible and obtain a high quality diaphragm (beating the vascular bundle (The fibers are loosened to have an appropriate length, swell and rupture vertically, and the fibers are easily entangled.) There is a problem that the production is extremely troublesome.

According to the present invention, the characteristics of the density, internal loss, and Young's modulus of a diaphragm can be balanced at a high level, the productivity of the diaphragm in a production process can be improved, and furthermore, forest protection can be achieved. Another object of the present invention is to provide an electroacoustic transducer having a high practical effect also from the viewpoint of the above.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a diaphragm is formed by pulverizing a fiber taken out from a kenaf stalk and a fiber taken out from a young culm of a bamboo shoot, while forming a diaphragm .
50% of fiber extracted from bamboo shoots
The ratio of the fibers obtained is 50% .

[0011] The present invention, while the fibers were removed from the fiber and bamboo young culm taken out from kenaf stems and混抄the wood pulp to form the diaphragm, Eject from kenaf stalks
50% of the extracted fiber, fiber extracted from bamboo shoots
Is 40%, and the ratio of wood pulp is 10% . Further, the present invention relates to a kenaf
50% fiber taken from stalks of bamboo and taken from young culm of bamboo grass
Vibrating plate made of 50% pulp
50% fiber taken from the stem of the naph and young culm of bamboo
A mixture of 40% of the fibers and 10% wood pulp
A moving plate is used.

[0012]

Therefore, the fiber 5 taken from the kenaf stem
0% and 50% of fiber taken from bamboo shoots are pulped and 50% of fiber taken from kenaf stem
And 40% of fiber taken from the bamboo shoot of bamboo are mixed with 10% wood pulp to form a diaphragm,
The rigidity and internal loss can be improved without increasing the density as a diaphragm for an electroacoustic transducer, and the use of wood pulp can be limited.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side sectional view showing an embodiment of an electrodynamic loudspeaker using the diaphragm of the present invention, FIG. 2 is a frequency characteristic diagram of the electrodynamic loudspeaker using the diaphragm of the first embodiment, FIG. 3 is a frequency characteristic diagram of an electrodynamic loudspeaker using the diaphragm of the second embodiment.

In FIG. 1, reference numeral A denotes a support plate having a center pole I projecting from the center of the upper surface. On this support plate A, a magnet B and an upper plate C are fixed in order. G is a voice coil that is loosely fitted on the upper portion of the center pole I and is supported by the frame D via a damper H. A peripheral portion of the diaphragm E and a peripheral portion of the frame D are connected to an upper portion of the voice coil G by an edge F formed on a ring.

The diaphragm E is formed by using fibers taken from kenaf stalks as a main material. Other materials mixed with the main materials are fibers taken from bamboo shoots and wood. Fibers are used.

Here, kenaf, which is the material of the diaphragm E, and young bamboo shoots of bamboo grass will be described. Kenaf is an annual grass of the family Malvaceae, and must be cultivated every year after felling. However, it grows to a height of about 4 m in 4 to 5 months, and an average of 20 t can be harvested per hectare. When converted to wood pulp, it is equivalent to pulp for 60 trees with a diameter of 20 cm and a height of 15 m. If it takes 15 years on average to grow into such a tree, 900 kenaf can be cultivated in one hectare. Trees will be saved.
In addition, the young culm of bamboo is a method of cutting only a young stem (young culm), and there is no influence on the parent bamboo grass, and it can be cut at the same place every year. Therefore, the use of kenaf and bamboo stalks can help protect the forest.

Although the bamboo fiber is short, the growing young culm has a thin fiber wall, and the fibers in the vascular bundle are gathered on the bundle. In order to work, a diaphragm with the property of increasing the rigidity and internal loss but not increasing the density is obtained, and it is possible to realize a highly dimensionally balanced diaphragm, and Kenaf and bamboo stalks can be made tough and strong paper without beating,
The productivity of the diaphragm can be improved.

Next, examples in which the diaphragm E is formed using fibers taken out of a kenaf stalk will be described in a first embodiment and a second embodiment.

[First Embodiment] In the first embodiment, the diaphragm E is formed by mixing 50% of a fiber taken out from a kenaf stalk and 50% of a fiber taken out of a young culm of Chishima bamboo grass. The properties of the diaphragm E are as follows: the density is 0.64, the Young's modulus is 3.50 × 10 ¹⁰ dyne / cm ² , and the internal loss is 0.035.

Therefore, a frequency characteristic diagram of a speaker using such a diaphragm E is shown by a solid line in FIG. The broken line in FIG. 2 indicates the frequency characteristics of a comparative example using a speaker using a diaphragm formed of wood pulp and having the same shape as in the first embodiment.

In FIG. 2, the frequency characteristic of the speaker using the diaphragm according to the comparative example shown by the broken line is about 16
It can be seen that the attenuation starts at 000 Hz. On the other hand, in the frequency characteristics of the speaker using the diaphragm according to the embodiment shown by the solid line, such attenuation is not recognized. In other words, 50% of the fiber taken from the kenaf stem,
According to the diaphragm E formed by mixing 50% of the fiber taken out from the young culm of Chishima bamboo grass, the rigidity of the diaphragm E is increased due to the improvement of the Young's modulus, and particularly the characteristics in the high band are improved. Broader and better frequency characteristics than the diaphragm are obtained.

In this embodiment, the young culm of Chishima bamboo is used as the young culm of bamboo. However, the kind of bamboo is not limited to this.

[Second Embodiment] In the second embodiment, the diaphragm E is made of fifty percent of fiber taken from a kenaf stalk, fifty percent of fiber taken from a young culm of Chishima bamboo grass, and ten percent of wood pulp.
The properties of the diaphragm E are as follows: a density of 0.66 and a Young's modulus of 3.30 × 10 ¹⁰ dyn.
e / cm ² and the internal loss is 0.034.

A frequency characteristic diagram of a loudspeaker using such a diaphragm E is shown by a solid line in FIG. The broken line in FIG. 3 indicates the frequency characteristics of a comparative example using a speaker using a diaphragm formed of wood pulp and having the same shape as that of the second embodiment.

In FIG. 3, the frequency characteristic of the speaker using the diaphragm according to the comparative example shown by the broken line is about 16
It can be seen that the attenuation starts at 000 Hz. On the other hand, in the frequency characteristics of the speaker using the diaphragm according to the embodiment shown by the solid line, such attenuation is not recognized. In other words, 50% of the fiber taken from the kenaf stem,
According to the diaphragm E formed by mixing 40% of fibers taken from the young culm of Chishima bamboo and 10% of wood pulp, the rigidity of the diaphragm E increases due to the improvement of the Young's modulus, and particularly in the high band. The characteristics are improved, and a wider frequency range and better frequency characteristics than the conventional diaphragm can be obtained.

In this embodiment, the young culm of Chishima bamboo is used as the young culm of bamboo. However, the kind of bamboo is not limited to this.

[0028]

As described above, according to the present invention, the characteristics of the density, the internal loss, and the Young's modulus of the diaphragm used in the electroacoustic transducer can be balanced in a high dimension. The frequency characteristics of the electro-acoustic transducer can be improved particularly in a high band, and good frequency characteristics can be obtained in a wide band.

Further, in the production process of the diaphragm, it is not necessary to beat the wood pulp for a long time, so that the productivity of the diaphragm can be improved. From a viewpoint, practical effects can be high.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the structure of an electrodynamic speaker according to one embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram of a speaker using the diaphragm according to the first embodiment.

FIG. 3 is a frequency characteristic diagram of a speaker using a diaphragm according to a second embodiment.

[Explanation of symbols]

 A Support plate B Magnet C Upper plate D Frame E Diaphragm F Edge G Voice coil H Damper I Center pole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-72474 (JP, A) JP-A-4-281697 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04R 7/02

Claims (3)

(57) [Claims] 1. A fiber formed from kenaf stalks and a fiber obtained from bamboo shoots, pulp-shaped and formed.
On the other hand, the percentage of fiber taken out of the kenaf stem
%, The vibration plate, characterized in that the proportion of fibers taken from bamboo young culm 50%. 2. A fiber formed by mixing fibers extracted from kenaf stems and fibers extracted from bamboo shoots into wood pulp .
On the other hand, the percentage of fiber taken out of the kenaf stem
%, Ratio of fiber taken out from bamboo shoots is 40%, wood
A diaphragm having a pulp ratio of 10% . 3. The use of the diaphragm according to claim 1 or 2.
An electroacoustic transducer for use.