JPS6016794A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a diaphragm for speaker with high internal loss and where a peak at a resonance point is suppressed by forming one or plural slots to a core member of the diaphragm. CONSTITUTION:A stylene-maleic anhydride copolymer foaming body foamed into 40 times as a core member is cut into a rectangular of, e.g., 250mm. long, 50mm. width and 5mm. thickness to form the core member 1. Three slots or slits 2, 2' each having a depth of 3mm. are provided along left and right short sides in the long side direction of the core member 1 at an interval of 3mm. by a cutter and an Al foil (20mum) is sticked to both the faces of the core member 1 to form a rectangular flat diaphragm. The slots are formed to the core member 1 because the rigidity of the diaphragm is decreased partially so as to suppress the peak value of the resonance of the diaphragm lower.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention has a 6-layer foam and a flat diaphragm with a surface material bonded to the surface of the core material, which has a high internal loss and suppresses the peak at the resonance point. This invention relates to a diaphragm for a speaker.

Conventional Structures and Problems Conventional flat-plate speakers often use an aluminum honeycomb core having hexagonal cells, or a soot/Deutte structure having a plastic foam core.

However, these conventional diaphragms have a low internal loss, a large peak at the resonance point, and when used as a diaphragm for a speaker, it is necessary to lower the peak using a mechanical filter or network, which results in high costs.

Purpose of the Invention The present invention uses a simple structure to partially reduce the stiffness to lower the Q of the diaphragm, thereby suppressing the σ peak at the resonance point without using an electrical or mechanical filter. The object of the present invention is to provide a high-performance speaker diaphragm that can be manufactured at low cost.

Structure of the Invention The present invention provides a speaker diaphragm in which the surface of a core material made of a foam (surface layer) is bonded to the surface of the core material. As a result, it is possible to provide a speaker diaphragm in which the peak at the resonance point where the internal loss is high is suppressed.

Description of examples Examples of the present invention will be described below.

Example 1 Styrene-maleic anhydride copolymer foam (
Dai-Lark: Trademark, Block Plastics Industry KK) foamed 4 times as long as shown in Figure 1, length 25 out, +
lJs OJ! JF, cut into a rectangle with a thickness of 5M, core material 1
shall be. Three grooves or slits 2.degree. 2' with a depth of 3 mm are formed along the short sides of the core material 1 on the left and right sides in the long side direction using a cutter at intervals of 6 mm from both ends. Ad foil (20 μm) was pasted as a surface material on both sides of this core material 1 to form a rectangular flat plate diaphragm.

The sound pressure frequency characteristics of this diaphragm are compared with the sound pressure frequency characteristics of a conventional rectangular flat diaphragm without grooves, as shown in FIG. In FIG. 2, a shows the characteristics of this embodiment, and b shows the conventional example.

Example 2 As shown in Figure 3, the same material as Example 1 was made with a diameter of 19 om.
A circular core material 3 is formed by cutting the core material 3 into a circular shape with a thickness of 10 mm and a thickness of 10 mm, and three concentric grooves or slits 4 having a depth of tsmrpr are provided at intervals of 5 mm from the outermost circumference of the core material 3.

Muta foil (20 μm) was pasted on both sides of this core material 30 to form a circular flat diaphragm. The sound pressure frequency characteristics of this diaphragm are compared with the sound pressure frequency characteristics of a conventional circular flat diaphragm without grooves, as shown in FIG.

In FIG. 4, a shows the characteristics of this embodiment, and b shows the characteristics of the conventional example.

In addition, in the above Example 1, there are six grooves (J, slit).
In Example 2 VC, three grooves or slits 4 are formed, but the number of grooves or slits is not limited to the number in Example 2, and may be one. Alternatively, multiple copies are sufficient. Even if the grooves or slits are not continuous, it is also possible to form discontinuous grooves or slits 4' as shown in FIG.

Further, according to experiments conducted by the present inventors, the grooves or slits are preferably formed in the vicinity of the nodal line 2-nodal circle generated by the resonance of the diaphragm;

It is preferable to form grooves or slits parallel to the nodal circles.

Effects of the Invention As described above, the present invention has the advantage that by forming grooves in the core material, the stiffness is partially reduced, the internal loss of the diaphragm is increased, and the peak at the resonance point is reduced. It is.

4.1n Ii? Figure 1 is a perspective view of the core material of a speaker diaphragm according to an embodiment of the present invention, and Figure 2 is a sound pressure frequency characteristic of a speaker using the same diaphragm and a conventional diaphragm. FIG. 3 is a perspective view of the core material of a speaker diaphragm according to another embodiment of the present invention, and FIG.
The figure is a sound pressure frequency characteristic diagram of a speaker using the same diaphragm and a conventional diaphragm, and FIG. 5 is a top view of the core material of a speaker diaphragm according to another embodiment.

1...heartwood, 2,2', mountain...groove or slit, 3
...Heartwood, 4,4'...marks, grooves or slits.

Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 4 Figure 5 4′

Claims (1)

[Claims] A speaker diaphragm comprising a core material made of foam and a surface material bonded to the surface thereof, the core material having one or more grooves or slits formed therein.