JPS597835Y2 - acoustic lens - Google Patents

Description

[Detailed description of the invention] The present invention relates to an acoustic lens that is attached to the front surface of a speaker, etc., and in particular, an acoustic lens formed using a three-dimensional irregular mesh porous metal body having communicating holes. It's about lenses.

Traditionally, the directional characteristics of sound in speaker systems, etc.
In order to particularly improve the directional characteristics in the high frequency range, for example, as shown in Fig. 1, a technology is available in which an acoustic lens 2 is attached to the front of a speaker unit 1 and the acoustic output is diverged and radiated through acoustic paths of different lengths. It has been proposed and put into practical use.

In FIG. 1, the speaker unit 1 is a so-called tweeter for reproducing high-frequency sounds separated from a driver unit 3 for acoustic output and a short horn 4. As shown in FIG.

The acoustic lens 2 has a cylindrical frame 5 in which a large number of punching metals 7, each having an opening 6 whose diameter increases in the cylindrical direction, are arranged in parallel with equal gaps. A flange portion 8 provided at the end of the frame 5 is bonded and fixed to the short horn 4 of the speaker unit 1.

However, in the conventional acoustic lens 2 using the punching metal 7 as described above, each punching metal 7 is provided with apertures 6 of different diameters, and each punching metal 7 is mounted separately in the frame 5. Because of this, not only the number of structural parts and manufacturing man-hours are large, but also the sound pressure of the acoustic output tends to cause so-called chattering phenomenon in each punching metal 7. It is difficult to obtain products that are highly practical.

Therefore, in view of the problems of the conventional example as described above, the present invention
It is an object of the present invention to provide an acoustic lens that can obtain arbitrary acoustic properties, does not cause the so-called chattering phenomenon due to acoustic output, and has a simple construction.

Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment.

The acoustic lens according to the present invention is made of a metal porous body 10 in the form of a three-dimensional irregular network having communicating holes 9a as shown in FIG. The acoustic lens is shaped into an arbitrary acoustic lens shape with t1 and the thickness of the peripheral portion different from each other to obtain desired sound transmission characteristics.

The metal porous body 10 is manufactured by, for example, making a foamed resin mold, allowing a plating solution to penetrate into the foamed resin mold by capillary action, depositing metal by a plating method, and then burning out the foamed resin. be done.

The metal part deposited by the above plating method
The skeleton 9b of the metal porous body 10 shown in FIG.
becomes.

FIG. 3 is an external perspective view showing an embodiment of the present invention, in which 11 is an acoustic lens from the first and second porous metal blocks IOA and IOB, and 12 is the acoustic lens. Reference numeral 11 indicates a speaker unit attached to the front surface, and 13 and 14 indicate a frame and a diaphragm of the speaker unit 12.

The first and second porous metal blocks 10A, IO
B is a plane (indicated by a dashed line in the figure) having a rectangular parallelepiped shaped porous metal buoy lock 10C as shown in FIG. 4 at an arbitrary inclination angle O.

) are obtained by cutting each inclined surface 1
A porous metal body is shaped into a wedge shape with 5A and 15B.

Each of the metal porous blocks IOA and IOB is attached to the front surface of the speaker unit 12 symmetrically in the radial direction and the thickness gradually decreases toward the center portion, and constitutes the acoustic filter 11.

In the embodiment described above, it is possible to improve the directivity of the acoustic output in the radial direction of the front surface of the speaker unit 12 to which the metal porous blocks IOA and IOB constituting the acoustic lens 11 are attached. The focal point of 11 can be arbitrarily set by adjusting the inclination angle 0 of each inclined surface 15A, 15B of each porous metal block IOA, IOB.

Moreover, each of the metal porous blocks IOA and 10B can be made by an extremely simple process of cutting the rectangular parallelepiped metal porous block 10C diagonally as described above.

5 and 6 are a perspective view of the main parts of another embodiment of the present invention and a plan view of the main part attached to the speaker unit 14. FIG.

In this embodiment, as shown in FIG. 5, the acoustic lens 21 is made of a metal porous body 10D shaped into a rectangular parallelepiped having a substantially semi-cylindrical notched inclined surface 25 in the central portion, installed on the front diameter of the

The acoustic lens 21 as described above can be made by cutting out the notch inclined surface 25 in a rectangular parallelepiped-shaped porous metal block, but when manufacturing the porous metal body by the method described above, it is necessary to use a foamed resin mold. By foaming or shaping the foam into the shape shown in FIG. 5 in advance, products of the same shape can be easily manufactured repeatedly.

It should be noted that the acoustic lens 31 in the embodiment shown in FIGS. 7 and 8, which will be described below, can also be easily manufactured by the above-mentioned method.

Each of the embodiments described above includes acoustic lenses 11 and 2 that improve the directivity of the acoustic output in the radial direction of the speaker unit 12.
1, however, in an embodiment in which FIGS. 7 and 8 show a perspective view of the main part and a cross-sectional view of the speaker unit 12 attached to the front, the directivity of the acoustic output is set to 360°. Improvements can be made in both directions.

That is, in this embodiment, as shown in FIG. 7, the acoustic lens 31 is made of a metal porous body 10E shaped into a disk shape having a parabolic cutout slope 35 in the center.
from the speaker unit 12 via the mounting plate 16.
It is attached to the front of the short horn 17.

Note that 18 in FIG. 8 indicates an opening formed in the mounting plate 16.

The acoustic lens 31 has a peripheral edge portion that is thicker over the entire circumference than the thickness t1 of the center portion of the disc-shaped metal porous body 10E, so that the acoustic output from the speaker unit 12 is emitted in the direction of the radiation axis. Directional characteristics can be improved over 360° with the center axis as the central axis.

In each of the above-mentioned embodiments, the acoustic lens is constructed by shaping the metal porous body into an arbitrary acoustic lens shape, so the number of parts in the structure is extremely small, 1 or 2, and the shape allows the acoustic lens to have the same shape. It is also possible to easily and repeatedly manufacture the product, reducing the number of manufacturing steps, and providing an extremely low-cost acoustic lens.

Furthermore, the sound transmission characteristics of the acoustic lens can be set arbitrarily, and since the metal porous body that makes up the acoustic lens is a one-piece structure, there is no so-called chattering phenomenon caused by acoustic output, and the performance is improved. It is also possible to provide an extremely good acoustic lens.

Note that if the acoustic lens is constructed using a metal porous body made of a metal material such as nickel Ni, there is no need for surface treatment, and further cost reduction can be achieved.

Here, regarding the example shown in FIG. 3 above, the frequency directivity characteristics and third harmonic distortion characteristics were actually measured when the acoustic lens was attached to the front of the speaker unit and when it was removed. The characteristic diagrams are shown in Figure 9 and Figure 1.
Shown in Figure 0.

As is clear from FIG. 9, according to the embodiment of the present invention,
It is possible to improve the frequency directivity characteristics in the 30° direction and the 60° direction with respect to the baffle plane.

In Figure 9, the thick line shows the characteristic line when the acoustic lens is attached, and the thin line shows the characteristic line when the acoustic lens is removed.The characteristic line in the 30° direction is shown as a solid line, and the characteristic line in the 60° direction is shown as a dashed-dotted line. .

Furthermore, as is clear from FIG. 10, according to the embodiment of the present invention, the third harmonic distortion level is reduced by 6 to 10 bB (around 2 to 5 KHz) within the frequency band used. Third harmonic distortion can also be reduced.

In Figure 10, the thick line shows the case when the acoustic lens is attached, the thin line shows the case when the acoustic lens is removed, the solid line shows the characteristic line of the original sound output level, and the dashed-dotted line shows the characteristic line of the third harmonic distortion level. ing.

As is clear from the description of each of the embodiments above, according to the present invention, it is possible to improve the directivity characteristics and the third-order distortion characteristics, and also to simplify and reduce manufacturing costs. It is possible to provide an acoustic lens with extremely good sound transmission characteristics that does not cause the so-called shading phenomenon caused by the output.

Note that the present invention is not limited to the above-mentioned embodiments, but includes many modifications, such as shaping a porous metal body into a convex lens shape.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway external perspective view showing a conventionally known general acoustic lens. FIG. 2 is an enlarged perspective view showing an example of the internal structure of a porous metal body applied to the present invention. FIG. 3 is an external perspective view showing an embodiment of the present invention. FIG. 4 is an explanatory diagram showing the method of manufacturing the acoustic lens of this embodiment. FIGS. 5 and 6 are a perspective view of the main parts of another embodiment of the present invention and a plan view of the main part attached to a speaker unit. FIG. 7 and FIG. 8 are an external perspective view of the main part and a cross-sectional view of the main part of still another embodiment of the present invention and a state in which it is attached to a speaker unit. Figures 9 and 10 are obtained by actually measuring the frequency directivity characteristics and third harmonic distortion characteristics for the example shown in Figure 3 above when the acoustic lens is attached to the speaker unit and when it is removed. FIG. 10, IOA, IOB, IOC, IOD, I
OE...Metal porous body, 11, 21, 31...Acoustic lens, 12...Speaker unit, 15A, 1
5B, 25, 35...notch inclined surface.

Claims (1)

[Scope of utility model registration request] What is claimed is: 1. An acoustic lens characterized in that, instead of using a three-dimensional irregular network-like metal porous body having communicating holes, the metal porous body has different thicknesses at the center and at the periphery.