JPS6355838B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speaker diaphragm having a Sanderch structure.

(Structure of conventional example and its problems) Recently, a planar diaphragm with a sanderch structure has been developed as a speaker diaphragm, in which skin materials are bonded to both the front and back surfaces of a lightweight and highly rigid core material. A speaker diaphragm having such a structure has a feature of extremely high bending rigidity compared to a conventional cone-shaped speaker diaphragm constructed from a single sheet.
Therefore, the piston movement range is expanded, and the reproduction frequency band can be extended. Therefore, the performance of a speaker diaphragm is determined by the frequency at which the diaphragm's divided vibration begins. In the divided vibration region, a unique vibration mode of the diaphragm occurs, causing peaks and dips in the sound pressure-frequency characteristics.

The resonance frequency of a plane diaphragm can generally be expressed by the following equation.

However, K: Frequency parameter a: Diaphragm radius D: Stiffness of the diaphragm σ: Surface density of the diaphragm μ: Poisson's ratio From the above equation, since the radius of the diaphragm is the same and the Poisson's ratio can be regarded as a constant, the diaphragm's It can be considered that the resonance frequency is determined by the stiffness D and the surface density σ.

FIG. 1, FIG. 2, and FIG. 3 are examples of vibration modes of a circular diaphragm. In the example shown in FIG. 1, the nodes are linear in the radial direction. In this case, the influence on the sound pressure-frequency characteristics is small due to the rigidity of parts added to the diaphragm, such as the voice coil bobbin.

The example in Figure 2 is a mode with a nodal circle, which appears at the second lowest frequency. In this case, since there is no effect of the rigidity of the parts added to the diaphragm, the influence of this mode appears as a peak on the sound pressure-frequency characteristics. Generally, this problem is solved by driving the nodal part to cancel this mode.

The example in FIG. 3 is a mode that appears at a higher frequency than the example in FIG. 2, and mainly vibrates around the diaphragm. To suppress this mode of vibration, the rigidity of the outer circumferential portion must be increased. When this mode occurs, the directivity characteristics are disturbed.

For these reasons, planar diaphragms have been made of aluminum honeycomb or synthetic resin foam as a core material, and skin materials with a high longitudinal elastic modulus are bonded to both sides of the core material to obtain a highly rigid diaphragm.

On the other hand, recently, a speaker diaphragm 3 has been proposed in which skin materials 2, 2' having a high modulus of longitudinal elasticity are bonded to both the front and back surfaces of a core material 1 having a corrugated cross section in the circumferential direction as shown in FIG. Since the diaphragm 3 has peaks and valleys extending radially from the center, it has great rigidity against bending in a direction perpendicular to the radial direction. However, it is weak against bending in the radial direction. Therefore, a speaker diaphragm like this diaphragm 3, which has a core material with peaks and valleys radiating from the center and a corrugated cross-sectional shape in the circumferential direction, vibrates in the mode shown in FIG. easily and have a negative effect on directional characteristics.

(Object of the invention) The present invention aims to expand the piston movement area,
The present invention provides a speaker diaphragm having a wide reproduction frequency band.

(Structure of the Invention) According to the present invention, in a speaker diaphragm having a Sanderch structure, the core material of which is made of a thin film, and the shape of which has peaks and valleys extending radially from the center, the outer periphery is circular. There are mountains in the circumferential direction. This increases the rigidity in the circumferential direction and, as a result, expands the piston movement area, thereby achieving the above objective. Hereinafter, embodiments of the present invention will be explained using figures.

(Description of Embodiment) FIG. 5 is a perspective view showing a part of the first embodiment of the present invention. The shape of the core material 4 is similar to the core material 1 in FIG. 4, with peaks 4a and valleys 4b extending radially from the center, but bent along the circumferential direction at the outermost periphery, at right angles to the peaks 4a. A valley 4c and a peak 4d are formed. 4e is a flat part that is bonded to the skin material 2' attached to the back surface. FIG. 6 shows a cross section of the core material 4 of the first embodiment with skin materials 2, 2' attached to both the front and back surfaces.

FIG. 7 is a perspective view showing a part of the second embodiment. The shape of the core material 5 has peaks 5a and valleys 5b extending radially from the center, as in the first embodiment. It bends at a right angle to the mountain 5a at the outer periphery, and forms a mountain 5d.
is formed. 5e is a flat part for adhering to the skin material attached to the back side. FIG. 8 is a sectional view showing a state in which skin materials 2, 2' are adhered to both the front and back surfaces of a core material 5 of the second embodiment. The core end portion is covered with an inclined portion 5f extending from the peak 5d to the flat portion 5e.

In the above embodiment, the circumferential cross section of the core material has a triangular wave shape, but it may have a rounded wave shape, a trapezoid, a rectangle, or other shapes.

(Effects of the Invention) As described above, the present invention increases the rigidity in the circumferential direction by providing ridges along the circumferential direction on the outermost periphery of a core material in which ridges and valleys extend radially from the center.
The occurrence of the asymmetric vibration mode shown in FIG. 3 can be suppressed.

In addition, as shown in FIG. 9, the diaphragm with the Sanderch structure is made of skin materials 6, 6' coated with adhesive.
A core material 7 is sandwiched between the two, and a press plate 8 is used to press and bond the core material 7. In this case, with the conventional core material, where the peaks and valleys radiate from the center and continue in this shape to the outermost edge as shown in Figure 4, the force during pressing causes the peaks and valleys to form as shown in Figure 10. Distortion occurs, and the thickness direction of the diaphragm becomes out of order. However, since the core material according to the present invention has a mountain formed on the outermost periphery, it is strong against deformation in the circumferential direction, and the above-mentioned problem can be eliminated.

Furthermore, the core material shown in Fig. 4 has low rigidity against bending in the radial direction, so deformation such as warpage easily occurs during the manufacturing process, but the core material according to the present invention shown in Figs. 6 and 7 has ridges in the circumferential direction. Because of its increased rigidity, it retains its shape and eliminates problems.

Further, the honeycomb diaphragm made of aluminum or the like shown in FIG. 11 is very unsightly because the honeycomb core 10 is visible from the end. The same can be said of the core 1 shown in FIG. Furthermore, in the above diaphragm, the space surrounded by the core material and the skin material is open at the end, so when the diaphragm vibrates at a certain frequency, the air column inside resonates, causing a peak in the sound pressure-frequency characteristics. Deep appears and has a bad influence. Conventionally, in order to solve the above two problems, the first
As shown in Figure 2, edge members 11 are bonded to the front skin material 9 and the speaker frame 12 to hide the edges and isolate them from the outside, thereby eliminating the influence of the above-mentioned resonance on the sound pressure-frequency characteristics. was. However, in this method, the end portion 11 of the edge member 11
A is visible and is not desirable in terms of design.

On the other hand, in the diaphragm using the core material according to the present invention, as shown in FIG.
Since the shape of the core is not directly visible from the outside, the edge member 11 can be attached not only to the front side of the skin material but also to the back side of the skin material. The effects of air resonance inside the material can also be eliminated,
It is said to have had the effect of killing two birds with one stone.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are diagrams showing the vibration modes of a circular planar diaphragm, and Figure 4 is a diagram showing a conventional vibration plate using a core material with peaks and valleys extending radially from the center to the outer periphery. FIG. 5 is a partial perspective view of a first embodiment of the core material according to the present invention, FIG. 6 is a sectional view of the first embodiment, and FIG. 7 is a perspective view of a diaphragm according to the present invention. FIG. 8 is a cross-sectional view of the second embodiment, and FIG. 9 shows the adhesion process of the core material and skin material in a diaphragm with a Sanderch structure. 10 is a diagram showing a conventional example in which the peak portion is deformed due to the bonding process of the core material and the skin material, FIG. 11 is a perspective view of a conventional honeycomb structure diaphragm, and FIG. 12 is a honeycomb structure FIG. 13 is a sectional view of an edge portion of a speaker using a diaphragm according to the present invention. 2, 2'...Skin material, 4, 5...Core material, 4
a, 5a...Mountain, 4b, 5b...Valley, 4c...Valley in the circumferential direction, 4d, 5d...Mountain in the circumferential direction, 5f...
slope of a mountain.

Claims (1)

[Claims] 1. In a speaker diaphragm with a sanderch structure in which skin materials are attached to both the front and back sides of a core material having a shape in which peaks and valleys extend radially from the center toward the outer periphery, circumferential ridges are formed on the outer periphery of the core material. established a department,
A speaker diaphragm characterized in that the inclined portion covers an end of the core.