JP2995929B2 - Speaker diaphragm - 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 for a loudspeaker used for an audio output device or the like.

[0002]

2. Description of the Related Art In recent years, a diaphragm made of a composite such as a honeycomb structure has been increasingly used for a speaker in order to improve its acoustic characteristics.

Hereinafter, a conventional speaker of this type will be described. FIG. 5 is a schematic cross-sectional view of a speaker using the speaker diaphragm of the related art and the present invention. In the figure, 1 is a plate, 2 is a magnet constituting a magnetic circuit together with the plate 1, 3 is a voice coil that vibrates according to an input signal, 4 is a speaker frame, 5 is a voice coil having one end fixed to the frame 5. 3 is a damper that supports the vibration-free counterbalance 3 freely. Numeral 6 denotes a flat plate diaphragm having a honeycomb structure for generating a sound wave (in the present invention, a flat plate diaphragm 2 having a core structure).
2) and 7 are edges provided around the plate diaphragm 6 to support the plate diaphragm 6 with elastic force, 8 are gaskets for fixing the edge 7 to the frame 4, and 9 are vibrations of the voice coil 3 The coupling cone is transmitted to the

The operation of the loudspeaker configured as described above will be described below. First, when an electric signal is applied to the voice coil 3, a magnetic field in a predetermined direction is generated in accordance with the direction, and a repulsive force or an attractive force is generated in the magnetic circuit. As a result, the voice coil 3 vibrates in the direction of the arrow A in the gap of the magnetic circuit while being supported by the damper 5. The coupling cone 9 transmits the vibration to the flat plate diaphragm 6, and the flat plate diaphragm 6 generates a sound wave corresponding to the vibration. Therefore, it is desired that the plate diaphragm 6 used for this type of speaker is light and has high rigidity.

An aluminum honeycomb plate diaphragm is most often used as this type of plate diaphragm conventionally used. Next, a plate diaphragm 6 used for such a speaker is shown in FIG. The manufacturing process will be described with reference to a) to (j).

In the manufacturing process of the honeycomb member shown in FIG. 1, first, a roll-shaped aluminum foil 10 is cut into a predetermined shape (a), and then an adhesive 11 is applied at regular intervals to form an adhesive applied foil 12. (B). Next, a large number of adhesive-coated foils 12 are laminated to form a laminated block 13 (c). Then, the laminated block 13 is cut at a predetermined width to obtain a slice block 14 (d). Finally, the honeycomb block 15 is manufactured by extending the slice block 14 in the vertical direction (e). Next, in the manufacturing process of the skin member shown in the figure, first, the roll-shaped aluminum foil 16 is cut into a predetermined shape (f), and then the adhesive 17 is applied to the entire surface to obtain the adhesive applied sheet 18 ( g). Then, the front skin member 19a and the back skin member 19b are cut into a shape corresponding to the honeycomb core member 15 (h). Next, in the final step, the front skin member 19a and the back skin member 19b are bonded to the front and back surfaces of the honeycomb core member 15, respectively (i), and the flat plate diaphragm 6 is obtained (j). At this time, in order to rapidly solidify the adhesive 17, the bonding is performed while maintaining the bonding surface at a high temperature.

[0007]

However, in the above-mentioned conventional structure, the thickness of the raw material aluminum foils 10 and 16 themselves is as thin as 20 to 30 μm, and the honeycomb core member 15 has a small thickness.
Has a first problem that deformation is likely to occur in many steps.

When a solvent-based adhesive is used for bonding the front skin member 19a and the back skin member 19b, the solvent sealed in the honeycomb core member 15 thermally expands, and the surface of the front skin member 19a and the back skin member 19b are exposed. Has a second problem that the shape tends to be uneven.

As described above, the aluminum foils 10, 16
Has a problem that the structure is complicated, the assembling requires high technology, and the manufacturing efficiency is low.

Further, it is ideal that the diaphragm of the speaker makes a piston movement over the frequency band to be used. However, if the diaphragm is deformed or divided vibration occurs during the vibration, the sound pressure-frequency characteristic, distortion rate, phase The characteristics and the like are degraded and hinder high-fidelity reproduction. Aluminum honeycomb diaphragm is
E / ρ of the diaphragm material (where E: elastic modulus,
ρ: density) is high and the high-band resonance frequency is high to some extent, but the internal loss coefficient ta of the material aluminum is high.
Since nδ is low, the reproduced sound when an audio signal is input is
There was a problem that it was easy to make a metallic sound.

All of these problems lead to deterioration of acoustic characteristics. As a solution to the first problem, it is conceivable to use a foam of resin instead of the honeycomb core member 15, but this causes a new problem that not only lacks heat resistance and solvent resistance but also decreases rigidity. I will.

The present invention has been made to solve the above problems, and
It is easy to assemble, prevents various deformations in the manufacturing process, has high manufacturing efficiency, and has durability, heat resistance, solvent resistance,
The present invention provides a loudspeaker diaphragm capable of improving rigidity, further preventing the diaphragm from deforming or generating divided vibration during vibration, and realizing excellent acoustic characteristics with a high high-band resonance frequency. The purpose is to:

[0013]

In order to achieve the above object, a speaker diaphragm according to the present invention comprises a core member and front and back graphite skin members provided on both front and back surfaces of the core member. Then, a graphite material having a high graphitization rate is used for one of the front graphite skin member and the back graphite skin member, and a graphite material having a graphitization rate lower than at least the graphitization rate is used for the other one. .

[0014]

Therefore, the present invention has a very high elastic modulus due to the above-mentioned structure. When this is used as a speaker diaphragm, the flexural rigidity of the diaphragm is very large, and the diaphragm may be deformed or divided during vibration. Vibration does not occur. Further, since graphite is used as the skin member, the specific elastic modulus E / ρ (where E: elastic modulus, ρ: density) is large, and when this is used as a diaphragm, the reproduction band of the speaker can be extended. it can.

Further, since a molded product of a composite of scaly mica and synthetic resin is used as the core member and graphite is used as the skin member, the internal loss is high. It is possible to obtain a speaker having excellent sound pressure-frequency characteristics, distortion factor, and phase characteristics without generating noise or having a metal-like distorted sound.

Further, since a composite of scaly mica and a synthetic resin is molded and used for the core member of the speaker diaphragm, assembly is facilitated and production efficiency can be improved.

[0017] Further, since the graphite and the graphitization rate can adjust the adhesiveness and the breaking strength of the material, the graphitization rate varies depending on the required characteristics of the front graphite skin member and the back graphite skin member. By using the skin members, speaker characteristics and durability can be controlled.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A speaker diaphragm according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing the structure of a speaker diaphragm according to an embodiment of the present invention.

In the drawing, reference numeral 20 denotes a core member formed by molding a composite of scaly mica and a synthetic resin; Thus, the plate diaphragm 22 is formed.

Next, the manufacturing process of the core member 20 will be described. The scale-like mica is dispersed and floated in water, paper is formed in the same manner as scooping paper, dried with hot air, and cured with epoxy resin. A 10 to 20 wt% toluene solution of the mixture of the agents is impregnated with a shower and dried at 40 to 50 ° C. with hot air to form a prepreg. This is cured at 150 to 180 ° C. for 10 to 40 minutes in a concave and convex mold while regulating the thickness to about 20 μm, thereby forming a core member 20 having a height of 1 mm.

FIG. 2 shows the external shape of the core member 20, the front graphite skin member 21a and the back graphite skin member 21b in one embodiment of the present invention. In this embodiment, a shape having corrugations radially from the center is shown (hereinafter, referred to as a mica core member).

Next, the manufacturing process of the front graphite skin member 21a and the back graphite skin member 21b will be described. First, a film having a thickness of 20 to 100 μm is formed from a polyimide resin or a polyoxadiazole resin. Next, heat treatment is performed at 800 to 1200 ° C. in a nitrogen atmosphere to release organic matter as a decomposition gas. On this occasion,
In order to prevent the film from foaming and expanding due to the release of the decomposition gas, pressure is applied from the front and back surfaces of the film, and the film thickness is controlled so as to be 10 to 20 μm. When it is further baked at 2000 to 3000 ° C., carbon as a component thereof sinters and is further graphitized. Graphite front and back graphite skin members 21 a and 21
b is formed.

The mica core member 2 formed as described above
3 is obtained by applying a non-solvent type adhesive such as an epoxy resin or a polyamide film on both front and back surfaces and thermocompression bonding the front and back graphite skin members 21a and 21b. .

As described above, according to this embodiment, it is possible to perform thermocompression bonding without using a solvent-type adhesive as in the related art. Further, since the bonding area of the mica core member 20 can be made larger than that of the conventional honeycomb core member, the front graphite skin member 21a and the back graphite skin member 21b can be firmly bonded.

Further, the graphite ratio can be adjusted by changing the calcination temperature (2000 to 3000 ° C.). If the calcination temperature is low, the graphitization ratio decreases and the carbon content decreases. Although E / ρ decreases as the number increases, the adhesiveness or the breaking strength in the surface thickness direction improves. In particular, when a speaker is required to withstand input power, as shown in FIG. 1, the adhesive strength between the plate diaphragm 22 and the coupling cone 9 that transmits the vibration of the voice coil 3 to the plate diaphragm 22 and the plate diaphragm 22 Since the strength of the bonding portion of the member is required, a skin member made of graphite having a relatively low graphitization rate is used as the back graphite skin member 21b, so that the flat plate diaphragm 22 and the coupling cone 9 are used.
Thus, the strength of the bonded portion can be ensured, and the input resistance and durability of the speaker can be improved.

A comparison of physical properties between the material used in this example and the material of the conventional flat plate diaphragm is shown in Table 1.

[0028]

[Table 1]

In Table 1, in particular, the specific elastic moduli of graphite A and graphite B are extremely higher than those of conventional aluminum paper, indicating that the sound propagation speed is high. The elastic modulus of the mica epoxy composite material is as high as aluminum, indicating that sufficient rigidity can be obtained when the diaphragm is formed.

On the other hand, the value of the internal loss of each of graphite A, graphite B and the mica-epoxy composite material is higher by at least one digit than that of aluminum, indicating that the ability to absorb unnecessary vibration is high. .

Regarding the material properties of graphite having different graphitization rates and the breaking strength of the bonding portion between the diaphragm and the coupling cone when these graphites are used as the back skin member, the specific elastic modulus is 98%. % (Calcination temperature 3000 ° C) compared to graphite A 75%
Although graphite B at a firing temperature of 2600 ° C. is slightly lower, the breaking strength of the bonded portion is higher.

Next, referring to FIG. 4, the flat diaphragm 2 of the present invention will be described.
2 will be described.

In the figure, A and B are the frequency characteristics of the speaker using the flat plate diaphragm of this embodiment, and C is the frequency characteristic of the speaker using the conventional flat plate diaphragm.

Here, A is the surface graphite skin member 2
1a is a frequency characteristic of a speaker composed of a diaphragm 22 using graphite A having a graphitization ratio of 98% and a back graphite skin member 21b using graphite B having a graphitization ratio of 75%, and B is a front graphite skin member 21a. And the back graphite skin member 21b is a frequency characteristic of a loudspeaker composed of a flat plate diaphragm 22 using graphite A having a graphitization rate of 98%.

Here, the sound pressure level with respect to the frequencies of A and B is extended to 20 kHz which is said to be the upper limit of the human audible band while maintaining approximately 100 dB. Thus, the sound quality in the high frequency region is improved. However, the upper limit frequency of A is slightly lower than that of B.

In this embodiment, the shape of the diaphragm is φ28 mm.
A disk-shaped one having a thickness of 1.2 mm was used, and the speaker was a tweeter for high sounds.

The thickness of the mica core member 20 is set to 20 μm.
m, height 1mm, front and back graphite skin members 2
Although the thickness of 1a and 21b is restricted to 10 to 20 μm, similar results can be obtained if the thickness is close to this.

Further, the front and back graphite skin members 21a and 21b are bonded to the mica core member 20 with an adhesive. The present invention is not limited thereto, and it is easy for those skilled in the art to make changes without departing from the gist of the present invention.

[0039]

As is apparent from the above embodiment, the present invention has a core member, and a front graphite skin member and a back graphite skin member provided on both front and back surfaces of the core member. By using a graphite material having a high graphitization rate for one of the graphite skin members and using a graphite material having a graphitization rate lower than at least one of the graphitization rates for the other one, the manufacturing efficiency of the flat plate diaphragm is reduced. This improves the heat resistance, solvent resistance, rigidity, and internal loss, and produces a speaker having excellent acoustic characteristics and high durability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a speaker diaphragm according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the speaker diaphragm.

FIG. 3 is a perspective view of the speaker diaphragm.

FIG. 4 is a frequency characteristic diagram of a speaker using the speaker diaphragm and a conventional speaker.

FIG. 5 is a schematic sectional view of a speaker to which the present invention and a conventional speaker diaphragm are applied.

FIG. 6 is a manufacturing process diagram of a conventional speaker diaphragm.

[Explanation of symbols]

 Reference Signs List 20 core member 21a front graphite skin member 21b back graphite skin member 22 flat plate diaphragm

Claims (3)

(57) [Claims] 1. A core member, a front graphite skin member and a back graphite skin member provided on both front and back surfaces of the core member, and one of the front graphite skin member and the back graphite skin member has a high graphitization rate. A diaphragm for a loudspeaker, wherein a graphite material is used, and a graphite material having a graphitization rate lower than at least the graphitization rate is used for the other one. 2. The speaker diaphragm according to claim 1, wherein a molded product of a composite of scaly mica and synthetic resin is used as the core member. 3. The diaphragm for a loudspeaker according to claim 1, wherein the graphite material is obtained by carbonizing and graphitizing the polymer sheet alone.