JPS59297A - Loudspeaker diaphragm - Google Patents

Abstract

PURPOSE:To form easily a titled diaphragm, and also to increase its rigidity, by forming its sectional shape in the circumferential direction to a waveform, and also setting the number of waves of the outside circumferential part to two times or more of the center part. CONSTITUTION:A section in the circumferential direction of a core material 4 is formed to a continuous waveform such as a trapezoidal wave, a triangular wave, etc. Also, a crest 4a of its waveform is made to branch to crests 4c, 4d at a point 4b on the way, and adjacent crests are connected by a plane 4g. As for the number of branches of the crest, two or more will do. By making the crest branch in this way, rigidity of the circumferential part can be raised, therefore, the pitch of the center part can be made larger than that of a fan- shaped core, and the forming is executed easily. Also, a skin material which is made to adhere to this core material 4 is divided into small areas in its circumference, therefore, a harmful resonance can be driven out of the band.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker diaphragm that is used in a speaker and has a sandwich structure in which a core material is lightweight and has high rigidity, and a skin material is bonded to the surface of the core material.

Generally speaking, a speaker diaphragm is lightweight and has a large longitudinal elastic modulus in terms of materials, and in terms of shape, it is appropriate to have a flat radiation surface in order to obtain flat sound pressure frequency characteristics. In order to achieve the above items, sheets of material with a high modulus of longitudinal elasticity (mainly aluminum alloy, carbon dalaphite) are bonded to both the front and back sides of a light and highly rigid core material (mainly honeycomb structure, synthetic resin foam). has been proposed as a speaker diaphragm.

A speaker diaphragm using the most typical two-cam structure as a core material (hereinafter referred to as a honeycomb core) will be described. This cam core is manufactured by the following method.

First, as shown in FIG. 1, adhesive ib is applied alternately at regular intervals between the thin sheets 1a serving as the core material, and these are stacked and bonded. Next, the bonded core material is cut to a certain width and stretched in the direction in which it is laminated to form a solid core 1 shown in FIG. 2. A speaker diaphragm is obtained by bonding skin materials to the front and back surfaces and processing them into a predetermined shape. The speaker diaphragm manufactured as described above has the characteristics of being light and having high rigidity, but on the other hand, it has the following drawbacks.

(1) It takes a lot of man-hours to manufacture, and the yield rate is still low, so the cost is high.

(2) Due to the structure of the core material, the honeycomb core is
The bending rigidity is large in the X direction shown in the figure, but small in the Y direction. Due to this directionality of bending rigidity, when it is made into a diaphragm, it has directivity and drives the diaphragm. This has a subtle effect on the position.

(3) If the diaphragm is made of a honeycomb core and the skin material attached to both sides of the core is a material with high resonance sharpness, a high peak will occur in the sound pressure frequency characteristics in the divided vibration region.

On the other hand, a fan-shaped core material 2 made of a material with a large internal loss and shown in FIG. 3 has been proposed as a structure that overcomes the above-mentioned drawbacks compared to a honeycomb core. However, in this structure, when the diameter of the diaphragm is increased, the pitch between the outer periphery of the ridge 2a and the adjacent ridge 2b increases, resulting in a lack of rigidity; If you reduce the pitch of the ridges on the inner periphery, the pitch of the ridges on the inner periphery will become very small.
The drawing ratio increases, making it difficult to manufacture due to problems such as material breakage. Further, as shown in Fig. 4, the skin material 3 attached to the front and back sides of the core material 2 is supported by the peaks 2a and 2b, and the natural frequency of 8 parts (slanted parts) of the skin material is the driving frequency of the diaphragm. When it matches, resonance occurs. In particular, if the area of the skin material S section is large, the natural frequency will be low, and if this frequency falls within the audible range, the vibration sound will be audible to the human ear, which is not preferable.

The present invention provides a diaphragm that eliminates the drawbacks of the conventional diaphragm having a honeycomb core and the diaphragm having a fan-shaped core 2. Examples of the speaker diaphragm of the present invention will be described below based on the drawings. explain.

FIG. 5 is a perspective view showing a part of an embodiment of the core material 4, which is a member constituting the speaker diaphragm of the present invention, in which the cross section in the circumferential direction has a continuous waveform such as a trapezoidal wave or a triangular wave. none,
The peak 4a of the waveform branches into peaks 4c and 4d at a point 4b, which forms an adjacent peak 4e.

4f is connected to plane 4g. Note that the number of branches of the mountain may be two or more.

6 and 7 are plan views of the core material 4. The example in FIG. 6 is a general circular core, and the example in FIG. 7 is a core with a hole in the center and the same diameter. A donut-shaped speaker diaphragm is obtained by pasting a skin material with holes.

FIG. 8 is a perspective view of a speaker diaphragm 5 completed by pasting the core material 4 according to the above embodiment and skin materials 3, 3' having high longitudinal elastic modulus on both the front and back surfaces of the core material, and FIG. 9 is a perspective view of the speaker diaphragm 5. 5 is a side view of a speaker diaphragm 5 with a coupling cone 6, a voice coil bobbin 7, and a voice coil 8 attached. FIG.

Next, a comparison will be made between the diaphragm structure of the present invention and a conventional planar diaphragm having a non-nicam structure. Generally, in a plane diaphragm, the position of the node is driven to eliminate the influence of the first natural vibration.

However, in an imaging plate having a non-uniform structure in which the rigidity is directional, the nodes of the first natural vibration are complicated, making the driving method difficult.

The diaphragm of the present invention has the advantage that since the peaks of the core material radiate out from the center, the nodes of the first natural vibration of the diaphragm are circular, making it easy to drive. Furthermore, by using a thermoplastic resin film as the material for the core material 4, it is possible to form deep drawing creases in a short time, which is impossible with metal foil. Therefore, it has the great advantage of being able to be manufactured at a lower cost than the non-nikum core, which requires a large number of manufacturing steps.

The diaphragm, which uses metal foil with low loss for both the core and skin materials, can reduce sound pressure due to split vibration.

Harmful peaks occur in the frequency response. However, in the present invention, as mentioned above, a thermoplastic resin film with large internal loss is used as the core material, so even if the diaphragm causes split vibration, the loss of the core material absorbs the harmful vibrations and prevents the occurrence of peaks. It is very effective in preventing and flattening the frequency characteristics.

Next, a comparison will be made between the diaphragm of the present invention and the fan-shaped core diaphragm shown in FIGS. 3 and 4. In the fan-shaped core 2 shown in Fig. 3, when the number of ridges is increased to increase the rigidity of the diaphragm, the pitch between the ridges at the center becomes smaller, so the center part has to be narrowed deeply. No.

However, in the diaphragm according to the present invention, the rigidity of the periphery can be increased by branching the ridges, so the pitch at the center can be made sharper than that of a fan-shaped core, and molding becomes easier. The shaded area S of the skin material shown in FIG. 4 is still supported by the pile of core material. Therefore, at the resonance frequency, the shaded portion S vibrates like a membrane and generates harmful sound. In the present invention, as shown in FIG. 10, by branching the peak of the core material 4, the skin material 3 is divided into smaller areas than in the past, and the resonant frequency is set higher than the number band of the peripheral plates of the unit. can be kicked out.

As described above, the present invention can provide a diaphragm that has many advantages compared to the conventional diaphragm having the Santoi-chi structure.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the manufacturing method of a honeycomb core used in a conventional diaphragm, Fig. 2 is a plan view of the honeycomb core, and Fig. 3 is a perspective view showing a part of a conventional fan-shaped core material. , FIG. 4 is a perspective view showing a state in which skin materials are pasted on the front and back sides of a fan-shaped core, FIG. 5 is a perspective view showing a part of the core material of a speaker diaphragm according to an embodiment of the present invention, and FIG. FIG. 7 is a plan view of the donut-shaped core material, FIG. 8 is a perspective view showing the sandwich structure speaker diaphragm of the present invention,
FIG. 9 is a side view showing a diaphragm according to the present invention with a voice coil etc. attached, and FIG. 10 is a comparison of the function of the sandwich structure speaker diaphragm of the present invention with that of the conventional example shown in FIG. FIG. 3.3'...Skin material, 4...Core material, 4a,
4 c, 4 d + 4 e + 4 f...'
：”A-wood mountain, 4b...The fork in the mountain, 4g...
Planar connecting portion, 5... Speaker diaphragm, 6... Coupling cone, 8... Voice coil. Figure 1 I〇-ri Figure 2 Figure 0 Figure 3 Figure 4 2a 2b Figure 5 t49 Figure 6 Figure 7 Figure 8 Figure 9

Claims (2)

[Claims] (1) In a speaker diaphragm made by bonding skin materials to both sides of a circular core material of constant thickness, the core material is formed into a continuous waveform such as a triangular wave or trapezoidal wave in the circumferential direction. A speaker diaphragm made of a resin film, characterized in that the number of waves on the outer periphery is at least twice the number of waves on the part near the center. (2) Claim (1) characterized in that the core material and the skin material have a hole in the center of the circular shape.
Speaker diaphragm described in section.