JPH0448073Y2 - - 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 41, a center pole 42, a front plate 43, and a back plate 44, as shown in FIG.
The diaphragm is supported by edges 47 so that the voice coil 46 fixed to the outer periphery of the diaphragm 45 is positioned in the magnetic gap formed by the center pole 42 and the front plate 43 of the magnetic circuit. The diaphragm 45 is driven through electric current to emit sound waves.

The diaphragm 45 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 peak was generated at the subsequent high-frequency resonance frequency _FH , resulting in deterioration of frequency characteristics and transient characteristics, which impairs the sense of hearing.

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.

In order to achieve the above object, the dome-shaped speaker according to the present invention includes a dome-shaped diaphragm 1, a voice coil bobbin 2 coupled to the diaphragm 1, and a voice coil 3 wound around the voice coil bobbin 2. , in a dome-shaped speaker having a vibration system consisting of an edge 4 fixed to the outer circumference of the diaphragm 1, the diaphragm 1 is made of a hard material and has a width of 3 to 50 mm of the total circumference of the diaphragm 1. % and whose radial width is within 50% of the radius of the diaphragm 1 is formed at one or more locations at a position that includes the nodal circle of the anti-resonance mode near the periphery of the diaphragm 1. At the same time, a voice coil bobbin 2, which has a smaller diameter than the diaphragm 1 and has a voice coil 3 wound around its lower end, is bonded to the spherical part of the diaphragm 1.
It is characterized by having a vibration system configured to drive the inner circumferential portion of.

[Effect]

In the vibration system having the above configuration, the stiffness at the outer periphery of the diaphragm differs along the circumferential direction, so significant anti-resonance and resonance in F _R and F _H as in the conventional example are dispersed and The resulting dips and peaks in the frequency characteristics disappear, resulting in flat frequency characteristics, and at the same time, significant resonance disappears, resulting in good transient characteristics.
The playback quality will be significantly improved.

〔Example〕

The structure of the vibration system of the dome-shaped speaker of the present invention will be explained in detail with reference to FIGS. 1a and 1b to 3.

In Fig. 1, the diaphragm 1 is made of a lightweight, highly rigid hard material such as metal, synthetic resin, synthetic resin reinforced with fibrous, scaly, or powdered high-rigidity filler, and has a dome shape. A slit 5 is provided around the periphery.

The size of the slit is within the range that includes the vibration node at _FH mentioned above, the width W is about 3 to 50% of the total circumference of the diaphragm, and the radial width d is the minimum width of a cut. Approximately 50% of the diaphragm radius from the width,
Experiments have shown that good results are obtained with one or more locations (two locations in the illustrated example) of about five locations.

Further, the slit shape does not need to be linear as shown in the figure. The shape is not limited, such as a circular arc parallel to the outer circumference of the diaphragm, a circular arc in the opposite direction, or an arbitrary curve, as long as the above-mentioned vibration node at _FH is included in a part thereof.

The edge 4 is generally formed as a separate member and adhered to the outer periphery of the diaphragm 1, but due to manufacturing reasons,
It may be molded integrally with the diaphragm 1.

The voice coil 3 has a smaller diameter than the diaphragm, and is bonded to the inner circumference of the diaphragm 1 at the upper end of the voice coil bobbin 2. Note that the voice coil bobbin 2 may be bonded to the slit 5 of the diaphragm 1 described above.

Whether the voice coil 3 is bonded to the concave side of the diaphragm 1 (FIGS. 1 and 2) or the convex side (FIG. 3) can be arbitrarily selected depending on the design purpose.

If it is glued to the concave side, the voice coil bobbin becomes longer and the weight increases, which is not good in terms of the conversion efficiency of the speaker, but it has the characteristic that the sound radiation surface becomes a convex surface and the directivity is broader than radiation from a flat or concave surface. . When bonded on the convex side, the characteristics are opposite to those on the concave side.

In the above embodiment, the cutout 5 may be closed with a viscoelastic material 7 as shown in FIGS. 2 and 3. Closing the notch 5 has the effect of preventing air leakage on the back surface of the diaphragm and further improving transient characteristics due to mechanical internal loss. In addition, as shown in FIG. 3, apart from the diaphragm 1, the inner periphery of the edge 4 made of a hard material is partially extended along the diaphragm 1 to form an extension 7, and the extension 7 opens the slit 5. A vibration system having a structure that covers a portion also belongs to the technical scope of the present invention.

〔effect〕

FIG. 5 shows the characteristics of the dome-shaped speaker according to the present invention in comparison with a conventional example.

The characteristics shown by the solid line are those of the embodiment shown in FIG. 1, where the diameter of the diaphragm is 25 mm, the w dimension of the slit is 10 mm, and the d dimension is 2 mm.

The characteristics indicated by the dotted line are those of a conventional example having diaphragms of the same diameter.

In the characteristics of conventional speakers, there is a dip due to anti-resonance at approximately 20KHz and a peak due to high-frequency resonance around 30KHz, whereas in the dome-shaped speaker of the present invention, significant peaks and dips disappear in the above frequency band. This shows that the structure of the vibration system according to the present invention is effective in dispersing and eliminating significant resonance and anti-resonance.

In addition, by using a voice coil with a smaller diameter than the diaphragm, it is possible to concentrate the magnetic flux in a small magnetic gap and achieve a high magnetic flux density, so it is possible to achieve high conversion efficiency even with a small magnetic circuit, making it economical. It is.

Furthermore, since the diaphragm is mainly made of a hard material and is lighter than a soft dome diaphragm, there is no drop in efficiency, and a dome-shaped speaker with excellent frequency characteristics and transient characteristics not seen in the past can be obtained. It is something that can be done.

[Brief explanation of the drawing]

1a and 1b are front views and side half-sectional views of the vibration system of the dome-shaped speaker of the present invention, and FIGS. 2 and 3 are half-sectional views of the vibration system of other embodiments of the present invention, respectively.
FIG. 4 is a sectional view of a conventional general dome-shaped speaker, and FIG. 5 is a frequency characteristic diagram. 1 is a diaphragm, 2 is a voice coil bobbin, 3 is a voice coil, 4 is an edge, 5 is a slit, 6 is a viscoelastic material, and 7 is an extension part.

Claims (1)

[Scope of utility model registration request] Vibration consisting of a dome-shaped diaphragm 1, a voice coil bobbin 2 coupled to the diaphragm 1, a voice coil 3 wound around the voice coil bobbin 2, and an edge 4 fixed to the outer periphery of the diaphragm 1. In a dome-shaped speaker having a system, the diaphragm 1 is made of a hard material, and the width is the same as that of the diaphragm 1.
The slit 5 has a size of 3 to 50% of the total circumference of the diaphragm 1 and a radial width within 50% of the radius of the diaphragm 1.
The voice coil bobbin 2 is formed at a position that includes the nodal circle of the anti-resonance mode near the periphery of the diaphragm 1, has a smaller diameter than the diaphragm 1, and has a voice coil 3 wound around the lower end thereof. A dome-shaped speaker characterized by having a vibration system configured to be bonded to a spherical part of a diaphragm 1 to drive an inner peripheral part of the diaphragm 1.