JPS61245790A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a diaphragm for speaker having a low density, a high rigidity, and a high internal loss by using the mixture of unbleached sulfate pulp and flax pulp as main materials for paper making. CONSTITUTION:The mixture obtained by mixing unbleached sulfate pulp and flax pulp is used as main materials for paper making. For example, flax to which a digester where the liquid ratio of 20% Na2SO3 solution to 4% NaOH solution is 1:7 is added is digested at 160 deg.C for 4hr to obtain flax pulp. This flax pulp is beaten by a beater to adjust the degree of beating to 75 deg.SR. Unbleached sulfate pulp swollen for about 10min is supplied to the beater and is beaten with about 4.0% pulp concentration to adjust the degree of beating to 50 deg.SR. Paper materials are adjusted to a pulp liquid of about 0.3% paper making concentration and are made into a sheet of a diaphragm by a paper making net tool which is formed into a cone and has 10cm diameter. This diaphragm is heated at 180-200 deg.C mold temperature and is pressured with a prescribed mold and is dried.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a vibrating body used in a speaker, such as a diaphragm and a center cap.

BACKGROUND ART Conventionally, an electrodynamic speaker as shown in the cross-sectional view of FIG. 1 has been known. In such an electrodynamic speaker, a pole piece 2 is placed in the center of the back plate 1,
A magnet 3 is placed on its peripheral edge. The plate 4 is placed on the magnet 3 and forms a magnetic gap with the pole piece 2. A voice fill bobbin 6 carrying a voice coil 5 is inserted into the magnetic gap so as to be able to vibrate freely, and the voice coil bobbin 6 is supported by a damper 7. A cone-shaped diaphragm 8 is coupled to the voice coil bobbin 6 at its center, and a center cap 9 is attached to the end of the cone-shaped diaphragm 8. The peripheral edge of the opening of the cone-shaped diaphragm 8 is supported by a frame 11 via an edge 10. The edge 10 is further secured to the frame 11 by a gasket 12. Note that the lead of the voice coil is connected to a terminal 14 provided on the side surface of the frame 11 via a tinsel wire 13.

In such a speaker, a diaphragm 8, a center cap 9
The voice coil bobbin 6 is a vibrating body for a speaker.

In order to faithfully convert an input signal to the voice coil 5 into an acoustic output in an electrodynamic speaker, it is necessary for these speaker vibrators to ideally move as a piston. This means that the vibrating body, especially the diaphragm and center cap, must be rigid and at the same time must have an appropriate amount of internal loss to damp unnecessary vibrations.

Furthermore, in order to enhance electroacoustic conversion, the diaphragm and center cap are desired to have a large Young's modulus and a moderate internal loss. In recent years, the applications of such speakers have been greatly expanded, and there is a strong demand in the market for speaker vibrators having even higher rigidity and higher elasticity.

Favorable conditions for a vibrating body, namely, reducing the weight of the vibrating body;
Since a vibrating body is required to have dynamic properties such as high rigidity, high elasticity, and high internal loss, metal diaphragms have recently been made of boron, aluminum, beryllium, or polymer films. However, although metal and polymeric film materials exhibit high values such as elastic modulus, they are inferior in other properties such as density and internal loss, so they are limited to some diaphragms or center caps for high frequency band reproduction. .

Therefore, for vibrating bodies such as full-range and woofer diaphragms, vibrating bodies made of fiber materials, especially pulp fibers, whose various physical properties can be controlled by paper-forming and drying methods, are still widely used.

Generally, the fibers used in these vibrating bodies are mainly fibers obtained from natural III, so-called wood bulbs. This wood pulp is combined with Manila hemp, kapok, etc. bast II.
Paper mixed with N is often used.

In addition, sulfate pulp (nirrtPt), which is a chemical pulp, is also used.
llp) is an unbleached sulfate valve (Unbleached
Kraft Pu1p (UKP)) and bleached sulfate pulp (Kraft Pu1p (BKP))
)) and. N (softwood) material on log chips,
L (hardwood) material is used and cooked using a mixture of sodium hydroxide and sodium sulfide as a cooking solution to elute lignin as thiolignin to obtain a sulfate bulb made of fibers mainly made of cellulose or the like. The outline of the manufacturing method is to put chips in a pot, add the above cooking liquid, heat at 170℃, 7 to 8 kg/Cm2
Steam to a moderate degree. After steaming, the fibers are washed with water and separated to obtain unbleached sulfate pulp (tJKP). Furthermore, bleach with chlorine, sodium hydroxide, bleaching powder, etc. to make a bleached sulfate valve (B).
KP).

Sulfate pulp is digested to remove cellulose-like substances with a low degree of polymerization. Although a large amount of anti-alkali pentozan remains in the pulp, the cellulose-like substances with a low degree of polymerization removed during cooking tend to be more easily beaten than the remaining bentozane.

However, with a vibrating body made mainly of wood pulp mixed with unbleached sulfate valves, etc., there is a limit even when trying to obtain the above-mentioned favorable conditions for the vibrating body, and thus the desired output sound pressure characteristics cannot be obtained. As an example of a conventional diaphragm, for example, a woofer diaphragm having a diameter of 10C11 is manufactured using the following pulp mixture as a main raw material.

Unbleached sulfate valve (beating degree 50°SR)...
...85wt% Manila hemp pulp (beating degree 75°SR) ...15wt% This mixed stock, the main raw material, is made into paper using a conical papermaking tool, formed and dried. Table 1 shows the dynamic properties of the diaphragm.

As shown in Table 1, it was not possible to obtain an imaging plate having physical properties suitable for a vibrating body such as high rigidity, high elasticity, and high internal loss using conventional mixed paper stock.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vibrating body for a speaker having low density, high rigidity, and high internal loss.

The vibrating body of the present invention is characterized in that it can be made by mixing unbleached sulfate bulb and flax pulp, and making paper using the resulting mixture as the main raw material.゛1-厘-1 Hereinafter, embodiments of the present invention will be described based on the accompanying drawings and the table below.

A woofer cone-shaped diaphragm having a diameter of 10C1 is manufactured as a speaker oscillating body in this example.

FIG. 2 is a flowchart showing the manufacturing process of this embodiment.

First, as a preparation step S1, a 20% Na2SO3 solution =
Flax to which a cooking liquor containing a 4% NaOH solution at a liquid ratio of 1 is added is subjected to cooking at a temperature of 160° C. for 4 hours. After cooking, the cooking liquor is completely washed and the flax is pulped.

Next, as a pre-beating step S2, 1.5 kg of flax pulp (Flax Plul) obtained by pulping was put into a predetermined beater and beaten for 30 minutes so as not to impair the physical properties of the pulp. The freeness was adjusted to a predetermined degree of 75°SR using a Schopper type freeness meter.

Next, as a simultaneous beating step S, unbleached sulfate pulp (UKP) that has been swollen for about 10 minutes is prepared in advance, and 8.5 kg of the unbleached sulfate pulp is transferred to the fly bar of the beating machine that supports the flax pulp. Up the roll, put it into the beating machine, adjust the flybar roll of the beating machine again at a pulp concentration of about 4.0%, and beat it for 90 minutes to obtain a beating degree of 50°S.
Adjust to R.

Next, in the papermaking process S4, the prepared paper stock is dyed to a predetermined color tone using sulfur dye, and the prepared paper stock is adjusted to a pulp liquid with a papermaking density of about 0.3%, and is pre-shaped into a conical shape. The diaphragm paper is made using a molded 10 CII diameter paper making jig.

Next, as a drying step S5, a predetermined mold is used to dry 3kQ.
Dry by heating and pressurizing at a mold temperature of 180 to 200° C. with a press pressure of /Cm2.

Next, as moisture-proofing treatment S6, a moisture-proofing solution having the following resin composition is prepared.

Aromatic solvents...66.2% Acetate esters...17.0% Ketones...7.0% Glycols (high boiling point)...・ 4.0% ketones 7.0% nitrified cotton 3.8% plasticizer (
DOP) - 1.0% resin 1.0% The prepared diaphragm is immersed in the moisture-proofing solution for about 10 minutes to apply moisture-proofing treatment to the diaphragm.

Next, as a drying step S7, a dryer is used at a temperature of 90 to 1
The product is dried by about 10 degrees using hot air at 00°C to fix the moisture-proofing solution to the fibers of the diaphragm.

Finally, in a forming step S8, the diaphragm is cut and formed to have predetermined inner and outer diameters to obtain the diaphragm of this example.

In Table 2, 1.0CIX4.5CI11 samples were cut from the diaphragm of this example prepared in this way, and the Young's modulus, internal loss, etc. were measured using the vibration lead method in an environment of a temperature of 20°C and a humidity of 60%. The results are shown below.

The diaphragm of this example has a Young's modulus of 98% and a propagation velocity/E/ρ of 38% when compared with the values of the conventional diaphragm shown in Table 1.
%, and the internal loss showed a remarkable improvement of 22%.

FIG. 3 is a graph showing the frequency characteristics when the diaphragm of this embodiment and the conventional diaphragm metals shown in Table 1 are assembled into a speaker. In the figure, curve A shows the characteristics of the diaphragm of this embodiment, and curve B shows the characteristics of the conventional diaphragm. As shown in the figure, the diaphragm of this example has improved characteristics in the vicinity of 2000 to 5000H2 compared to the conventional diaphragm,
In addition, the bandwidth has been widened and performance has been significantly improved. This is because the diaphragm of this example has increased rigidity and improved internal loss.

Flax fiber, which is a bast fiber, has many striations and knots on its surface, and its cross section is polygonal. The tensile strength of flax fibers is approximately twice that of cotton fibers, but the elongation is extremely low. Flax fibers come in a variety of colors, but light yellow-brown is the best. Bleaching breaks down the pectin in the fibers, reducing weight and strength. Therefore, in order to exhibit strength, it is preferable not to bleach it.

Traditional wood valves especially other bast fibers (three poles, Manila hemp)
In terms of the physical properties of the diaphragm obtained by mixing with an unbleached sulfate bulb, Young's modulus, propagation velocity, and internal loss are the first
The values shown in the figure are considered to be approximately the limit values. However, in the diaphragm of this example, its Young's modulus and propagation velocity values are comparable to those of metal diaphragms, and its internal loss is significantly improved compared to general pulp diaphragms.
Furthermore, its density is becoming smaller. Therefore, the diaphragm of this example can be said to be a diaphragm that is lightweight and has high rigidity, high elastic modulus, and high internal loss. Furthermore, the diaphragm of this example has excellent physical properties such as bending strength and tensile strength, and is highly durable, so that it can be used in a wide range of applications from lighters to woofers as a diaphragm for speakers.

In the above embodiment, a diaphragm is manufactured and explained as a vibrating body for a speaker, but it is clear that a center cap having the same effect can be obtained.

Effects of the Invention As mentioned above, according to the present invention, there is a vibrating body obtained by paper-making a mixture of flax pulp cooked by the soda method using sodium hydroxide and unbleached sulfate bulb and beaten at the same time. Therefore, a vibrating body having better physical properties than a vibrating plate body produced by conventional mixed papermaking using unbleached sulfate valves can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the electrodynamic speaker, FIG. 2 is a flowchart showing the manufacturing process of this embodiment, and FIG. 3 is a diaphragm of this embodiment and a conventional diaphragm shown in Table 1. 3 is a graph showing frequency characteristics when assembled into various speakers. Explanation of symbols for main parts 1... Back plate 2... Pole piece 3... Magnet 3 4... Plate 5... Voice coil 6... Voice coil bobbin 7... Damper 8... Cone-shaped diaphragm 9... Center cap 10... Edge 11... ... Frame 12 ... Gasket 13 ... Tinsel wire 14 ... Terminal

Claims (1)

[Claims] A vibrating body for a speaker, characterized in that it is made from a paper using a mixture obtained by mixing unbleached sulfate pulp and flax pulp as a main raw material.