JPH0129910Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to an improvement of the vibration system of a dome-shaped speaker in the field of electroacoustic equipment.

[Conventional technology]

A dome-shaped speaker generally has a magnet 21, a center pole 22, a front plate 23, and a back plate 24, as shown in FIG.
The voice coil 26 fixed to the outer periphery of the diaphragm 25 is supported by the edges 27 so that the voice coil 26 fixed to the outer periphery of the diaphragm 25 is positioned in the magnetic gap formed by the center pole 22 and the front plate 23 of the magnetic circuit, and the voice coil 26 receives a sound current. The diaphragm 25 is driven through the diaphragm 25 to emit sound waves.

The diaphragm 25 is usually made of a lightweight and highly rigid material such as duralumin in order to make the divided vibration frequency as high as possible and improve the frequency characteristics.

Another configuration of the dome-shaped speaker is that the diaphragm is made of a soft material with extremely high internal loss.
There are so-called soft dome speakers.

[Problems to be solved]

In the conventional example described above, the diaphragm using a high-rigidity material has low mechanical internal loss as a material, so at frequencies higher than the piston vibration range,
The vibration energy transmitted from the periphery of the diaphragm and the vibration energy reflected at the center of the diaphragm interfere with each other, causing vibration nodes near the outer periphery of the diaphragm due to so-called anti-resonance. Since the vibration phase of the diaphragm outside and inside this vibration node is opposite to each other, the frequency of the anti-resonance is
A dip occurs in the frequency characteristics in _FR .
Furthermore, a large peak occurs at the reproduction limit frequency _FH , deteriorating the frequency characteristics and transient characteristics, and impairing the hearing sense.

In addition, in the latter type of soft dome speaker, the internal loss of the diaphragm is extremely large, so resonance and anti-resonance are unlikely to occur, but the diaphragm has a large mass and it is difficult to transmit vibration energy, so the conversion efficiency as a speaker is extremely low. It was hot.

[Purpose of invention]

The present invention eliminates the drawbacks of the conventional example described above and uses an improved vibration system to prevent anti-resonance from occurring.
The purpose is to obtain a dome-shaped speaker with good frequency characteristics and efficiency.

[Means for solving problems]

In order to achieve the above object, the diaphragm of the dome-shaped speaker according to the present invention is a diaphragm that is thermoformed by impregnating a base material made of cloth or nonwoven fabric with an excipient. The type and impregnation state are dome-shaped, using one or more soft excipients around the periphery, or providing an area lacking excipients,
It is characterized in that a hard excipient material is used in the remaining area.

[Effect]

In the diaphragm with the above structure, the area where hard excipients are used has extremely high rigidity as a diaphragm material, but the area where soft excipients are used or the area where no excipients are omitted has low rigidity. As a result, the stiffness near the periphery of the dome-shaped diaphragm varies depending on the location, so the divided vibration becomes irregular and does not have a regular pattern corresponding to the geometric shape of the diaphragm. Resonance and anti-resonance no longer occur, and the peaks and dips in the frequency characteristics of F _R and F _H described above are dispersed and the frequency characteristics approach flatness.
Furthermore, since there is no significant inherent resonance, the transient characteristics are also good.

〔Example〕

The vibration system, which is a feature of the dome-shaped speaker according to the present invention, as shown in FIGS. The voice coil 3 is wound around a voice coil 3, and an edge 4 is provided at a joint between the diaphragm 1 and the voice coil bobbin 2.

The diaphragm 1 is made of a base material 13 such as a woven or nonwoven fabric made of synthetic fibers, natural fibers, or inorganic high-rigidity fibers.
The diaphragm 1 is partially impregnated with a different excipient material and thermoformed into a dome shape. A soft portion 11 impregnated with a soft excipient material is provided, and a shaft portion 12 is formed by impregnating the remaining region with a hard excipient material such as epoxy resin. In order to achieve the object of the present invention, it is desirable that the rigidity of the hard part 12 after molding is at least twice the rigidity of the soft part 11. Furthermore, the same applies to those in which the excipient material of the soft part 11 is omitted, or those in which the same part is molded without the excipient material and a viscoelastic material such as rubber is applied to the soft part 11 after molding. Since it has the following effects, it falls within the technical scope of the present invention.

According to experimental results, the size of the soft portion 11 is such that the width A is approximately 3 to 33% of the total circumferential length of the diaphragm 1, and the radial depth d is approximately 1 to 50% of the radius, or approximately 50% of the radius. The appropriate depth H in the horizontal direction is about 10 to 80% of the total height of the diaphragm 1. Further, although the shape of the soft portion 11 shown in the drawing is an arcuate shape surrounded by the outer periphery and the string, the shape is not limited as long as it falls within the above-mentioned size. Furthermore, when the soft parts 11 are distributed at multiple locations, it is not necessary that each soft part has the same shape. Rather, different shapes and distribution states tend to increase the resonance dispersion effect described above.

Furthermore, the edge portion 4 or the voice coil bobbin 2 in the vibration system of the dome-shaped speaker of the present invention is generally constructed of a separate member from the diaphragm 1;
A vibration system in which the edge portion 4 and the diaphragm 1, or the voice coil bobbin 2 and the diaphragm 1 are integrally molded from the same material, is also included within the technical scope of the present invention. These have the advantage of being inexpensive to manufacture.

〔effect〕

FIG. 3 shows the frequency characteristics of the dome-shaped speaker according to the present invention in comparison with a conventional example.

The solid line indicates the characteristics of the illustrated dome-shaped speaker of the present invention, and the dotted line indicates the characteristics of the conventional example. The example is a high-pitched dome-shaped speaker with a diaphragm diameter of 25 mm.In the conventional example, a significant dip appears at 20KHz and a high-level peak appears at 30KHz due to anti-resonance and resonance of the diaphragm, but the dome of the present invention In a type speaker, these peaks and dips disappear, and unnecessary bands around 22KHz and above are blocked. Moreover, no decrease in efficiency is seen. This is because soft parts with different rigidities are distributed in the parts where vibration nodes occur, so significant resonance and anti-resonance are dispersed, and the high-frequency driving force is partially attenuated by the soft parts, and the diaphragm This seems to be because the weight of the

[Brief explanation of drawings]

Figures 1a and b are a front view and partially enlarged half-sectional view of the vibration system of the dome-shaped speaker of the present invention, Figure 2 is a cross-sectional view of a general dome-shaped speaker, and Figure 3 is a frequency characteristic diagram. . 1 is a diaphragm, 11 is a soft part, 12 is a hard part, 1
3 is a base material, 14 is a soft excipient, 15 is a hard excipient, 2 is a voice coil bobbin, 3 is a voice coil, and 4 is an edge.

Claims (1)

[Claims for Utility Model Registration] 1. A dome-shaped diaphragm 1, a voice coil bobbin 2 coupled to the lower outer circumference of the diaphragm 1, a voice coil 3 wound around the voice coil bobbin 2, and the diaphragm 1. A dome-shaped speaker having a vibration system consisting of an edge 4 bonded near the joint with the voice coil bobbin 2, in which the diaphragm 1 is thermoformed by impregnating a base material 13 made of cloth or nonwoven fabric with a shaping material. and the type and impregnation state of the excipient material is such that the soft excipient material 14 is used at one or more locations around the periphery of the dome-shaped diaphragm, or the soft portion 11 without excipient material is formed. A dome-shaped speaker characterized in that it is a diaphragm having a hard part 12 formed by using a hard shaping material 15 in the remaining area. 2. The dome-shaped speaker according to claim 1, wherein the diaphragm 1 and either the edge 4 or the voice coil bobbin 2 are integrally molded from the same material.