JPS61154300A - Diaphragm - Google Patents

Abstract

PURPOSE:To suppress a peak at a high threshold frequency in a sound pressure frequency characteristic without damaging a sensitivity by providing a damping layer of an acryl viscoelastic sheet between both sides of a core timber and a skin timber. CONSTITUTION:A sandwitch structured diaphragm consists of, for example, glued skin timbers 3 and 4 pasted together with the damping layer 6 which, through an adhesive layer 2, has an adhesive acryl viscoelastic sheet having some 50mum of thickness on the both sides of the core timber 1 that is honey- comb structured on a plate. Or the skin timber which is made by skin timbers 7 and 8 glued facing each other the damping layer 6 of the acryl viscoelastic sheet between can be pasted on, at least, one side of the core timber 1.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a diaphragm for a speaker.

[Conventional technology]

A typical flat-plate type diaphragm generally used in speakers has a honeycomb-structured core material f1. shown in FIG. Skin materials (3) and (4) are adhered to both surfaces of the cylindrical body through an adhesive layer (2), respectively.

When a diaphragm with such a configuration is used in a speaker, its sound pressure frequency characteristics will be as shown in the curve (H) in Figure 4.At this time, depending on the height of Q of the diaphragm component material, the sound pressure frequency characteristic will be 2 kHz.
A peak of about 20 dfl occurs.

This frequency (that is, the high-frequency limit frequency fh) changes depending on the dimensions of the diaphragm, but if the typical configuration shown in FIG. 5 is adopted, the height of the peak does not change much. Furthermore, this peak is very audible and is one of the major factors that limits the high frequency range of the unit when configuring a so-called multi-speaker system. Therefore, efforts have been made to reduce the height of this peak by various techniques.

For example, as shown in Fig. 6, the core material f11 and the skin material (3
) and (4) through an adhesive layer (2) with a thickness of 0.
3-0! A diaphragm with a urethane damping layer (5) of 'imm has also been proposed.

(Problems to be Solved by the Invention) However, despite efforts such as disposing such a urethane layer, unfavorable results such as an increase in mass and a decrease in the peak frequency fh have occurred. For example, when a urethane damping layer (5) is added, the sound pressure frequency characteristic becomes as shown in curve (n) in Figure 4, and although the peak is suppressed, it can be seen that the sensitivity decreases as the mass increases. It will be done.

The present invention provides a diaphragm for a speaker that can reduce the added mass and suppress the peak at frequency fh that occurs on the sound pressure frequency characteristics.

[Means for solving problems]

The present invention is a diaphragm having a sandwich structure in which skin materials are disposed on both sides of a core material, in which a damping layer made of an acrylic viscoelastic sheet is provided on the skin material. In this case, the acrylic viscoelastic sheet is placed between the core material and both skin materials, or between the core material and one of the skin materials. In addition, a skin material is attached to both sides of the braking layer of the acrylic viscoelastic sheet, and this is considered as a new skin material, and this skin material is placed on both sides or either side of the core material. .

[Effect]

By providing a damping layer made of an acrylic viscoelastic sheet on the skin material of the diaphragm having a sand inch structure, the peak at frequency fh that occurs on the sound pressure frequency characteristics can be suppressed to a low level. Further, since the amount of w added to the damping layer by the acrylic viscoelastic sheet is small, the sensitivity does not decrease.

〔Example〕

Examples of the diaphragm according to the present invention will be described below.

FIG. 1 shows an embodiment of the present invention. In this example, adhesive acrylic viscoelastic sheets (Vjsco I'!1a manufactured by Sumitomo 3M Co., Ltd., manufactured by Sumitomo 3M Co., Ltd.) are used on both sides of a core material (1) with a honeycomb structure provided in the shape of a flat plate.
stic Material (FRPt name νI'!M
)) The skin materials (3) and (4) to which the brake N (6) is bonded are bonded together via the adhesive layer (2).

FIG. 2 shows another embodiment of the invention. This example is a skin material (3) in which the damping material N (6) made of the above-mentioned acrylic viscoelastic sheet is attached to one side of a core material (1) with a honeycomb structure.
and adhere only the core material (4) to the other surface of the core material (1).

The weights of the diaphragm of the present invention and the conventional diaphragm of FIGS. 5 and 6 are shown in the table below. Diameter 200m on each side
, a diaphragm with a thickness of 8 mm was used. The core material is an aluminum honeycomb structure with a pitch of 1/4 inch and a core height of 8.
The skin material was made of aluminum with a thickness of 40 μm.

On the surface, the sound pressure frequency characteristics of a speaker using the diaphragm of the present invention shown in Fig. 1 are as shown by the curve (Iff) in Fig. 4, and the peak at the upper limit frequency fh is about 6 dB. It's subsided. In addition, the sixth brake using a urethane damping layer
In the case of the figure, peak suppression is almost the same as the present invention as shown by the curve (Tr). However, in terms of mass, as is clear from the table, the diaphragm of the present invention shown in Fig. 1 is 5.5g lighter than the one shown in Fig. 6, and the sensitivity is as shown in Fig. 5 without braking. It is about the same level as the camera board. The diaphragm shown in FIG. 6 with the urethane damping layer has reduced sensitivity.

Furthermore, in the case of Fig. 2 in which the damping layer (6) made of an acrylic viscoelastic sheet is placed on only one skin material of the diaphragm,
Although not shown, the peak at frequency fh only reaches about 8 dB, and in terms of mass, it is 7.9 g lighter than the one in Figure 6 with a urethane damping layer, and the one in Figure 5 without damping. The increase is only 2.4g compared to the original.

On the upper side, the damping layer of the acrylic viscoelastic sheet is covered with a skin material (
3) and (4), but in addition, for example, as shown in Fig. 3, a braking N(
Skin materials (7) and (8) may be attached to both sides so as to sandwich 6), and this may be considered as one skin material, and this skin material may be placed on at least one of the core materials Tll. .

〔Effect of the invention〕

According to the present invention described above, in a diaphragm with a sand inch structure in which skin materials are arranged on both sides of a core material, a damping layer made of an acrylic viscoelastic sheet is provided on the skin material, so that sensitivity can be improved without impairing sensitivity. The peak at the high limit frequency fh in the sound pressure frequency characteristic can be suppressed. Furthermore, the weight can be reduced compared to conventional damping materials such as urethane layers. Furthermore, since the Acrif viscoelastic sheet itself has adhesive properties, if aluminum or the like is used as the skin material, it is possible to avoid reducing the number of adhesive layers, and the weight can be further reduced. In addition, the cell squealing phenomenon peculiar to a flat plate diaphragm with a sandwich inch structure can be reduced by allocating the skin material.

[Brief explanation of drawings]

1 and 2 are sectional views showing an embodiment of the diaphragm according to the present invention, FIG. 3 is a sectional view showing another embodiment of the diaphragm according to the present invention, and FIG. 4 is a sectional view showing an embodiment of the diaphragm according to the present invention. A sound pressure frequency characteristic diagram comparing a speaker and a speaker using a conventional diaphragm, and FIGS. 5 and 6 are cross-sectional views of the conventional diaphragm, respectively. (]) is core material, (2) is adhesive layer, +31 +41
+71 +81 is skin material, (5) is urethane damping layer,
(6) is a damping layer made of an acrylic viscoelastic sheet.

Claims (1)

[Claims] A diaphragm having a sandwich structure in which skin materials are arranged on both sides of a core material, and a damping layer made of an acrylic viscoelastic sheet is provided on at least one of the skin materials.