JPH01226298A - Acoustic lens device - Google Patents

Abstract

PURPOSE:To efficiently diffuse the directivity of a speaker by forming an acoustic lens by using a porous sintered metal plate. CONSTITUTION:The porous sintered metal plate 2 is fitted to the speaker 1 by screws 3. Thus, since the opening area of a secondary sound source can be formed by simple press and punch work, and can be fixed by simple screw fixing, etc., and the intensity distribution of the sound source can be controlled, the directivity can be easily expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an acoustic lens device for improving the directivity of speakers for audio reproduction.

Conventional technology Conventionally, this type of audio reproduction speaker lacks indirect sound components in frequency bands with sharp directivity.
This impairs the sound quality, and the sound quality changes greatly depending on the listening position.

FIG. 4 shows the configuration of a conventional acoustic lens device.

In FIG. 4, a plurality of disc-shaped perforated plates 42 with small holes 41 bored therein and having different center hole diameters are attached to the inner side of a fixed frame 44 attached to the front surface of a speaker 43 via an elastic body 45.
This figure shows an acoustic lens device arranged in multiple layers so that the center hole diameter becomes larger sequentially from the speaker opening side. Even in the above-mentioned conventional example, the sound path is formed to be short at the center, and by taking advantage of the fact that the sound propagation is delayed by the length of the sound path formed between the plates, equal phase is achieved. By making the wavefront arc-shaped, the directivity can be expanded.

Figure 5 shows another conventional example in which directivity was improved by using porous ceramic material to provide large air resistance (acoustic resistance) around the speaker aperture. 52 represents a speaker, 52 represents a fixed frame, and 53 represents a porous ceramic.

Problems to be Solved by the Invention However, the conventional acoustic lens 3 shown in FIG.
Although the 7 device can control the phase distribution, it has the disadvantage that the intensity distribution of the sound pressure hardly changes, and the effect of spreading, regulating, and so on is small. In addition, there is a disadvantage in that there are many parts that need to be dripped, which is disadvantageous in terms of ease of assembly and cost. In addition, although the other conventional acoustic lens device shown in FIG. 5 improves the diffusion effect by controlling the phase distribution and sound pressure distribution,
Ceramic materials have poor workability and shape limitations, are expensive and impractical, and have the disadvantages that the materials themselves are brittle and susceptible to impact.

The present invention solves these conventional problems, and provides an acoustic lens device that has a large diffusion effect, can be easily attached to a speaker at low cost, has excellent acoustic performance, and is easy to mass produce. The purpose is to

Means for Solving the Problems In order to achieve the above object, the present invention provides a porous metal sintered plate with a hole in the center on the diaphragm of the speaker or in front of the horn opening, thereby adjusting the phase of the sound source. Controlling the distribution (changing the propagation path length so that the phase at the center advances from the outside) and controlling the intensity distribution (sound pressure distribution) of the sound source (increasing the intensity at the center compared to the outside) )
It is designed to perform efficiently.

Effects The present invention has the following effects due to the above configuration. That is, if the diaphragm or horn opening is used as the primary sound source, the opening provided in the center of the porous sintered metal plate is used as the secondary sound source.The effective area of the sound source can be reduced and the directivity can be widely diffused.

In addition, the porous metal sintered plate has excellent workability such as press punching, and the center opening area (effective area of the sound source) and shape can be easily processed to any desired shape.Also, by making it multi-layered, it can be used to control the phase distribution of the sound source. , the intensity distribution of the sound source can be easily controlled.

It also has excellent durability and is relatively inexpensive, so
It has the effect of being highly mass-producible.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In Figure 1(a), 1 is a speaker, 5...-
- The state in which the porous metal sintered plate 2 is attached to the screw 3 is shown. Further, FIG. 6B shows a state in which porous metal sintered plates 5, 6, and 7 having different central opening areas are layered in order from the opening side of the speaker 4 in order of decreasing opening area.

As described above, according to the above embodiment, the opening area of the secondary sound source can be formed by a simple press punching process in FIG. Since distribution control can also be performed, the directivity can be easily widened.

In addition, in FIG. 1(b), the intensity distribution and phase distribution of the p1 sound source can be changed by layering porous metal sintered plates 5.6.7 with different openings formed in the same manner as in FIG. 1(a). It is possible to perform control and further enhance the diffusion effect.

Further, FIG. 2 shows various examples of shapes that take advantage of the excellent workability of the porous sintered metal plate. Figure 2 (a) shows the difference in the diffusion direction depending on the shape of the opening in the center, and Figure 2 (b) shows the cross sections 6, \, -7 when installed in a cone shape, dome shape, and horn shape, respectively. An example of a surface shape is shown.

FIG. 3 shows the embodiments (a) and (b) shown in FIG. 1 above.
This is a measurement value of the frequency characteristics and directional characteristics of a full-range cone speaker.
Figure (a) shows the characteristics without an acoustic lens, Figure 3 (b)
indicates the characteristics in Example (a) shown in FIG. 1 above,
Further, FIG. 3(c) shows the characteristics of the embodiment (b) shown in FIG. 1 above.

Effects of the Invention As is clear from the above embodiments, the present invention makes it possible to easily and inexpensively control the intensity distribution of a sound source and the phase distribution of a sound source by forming an acoustic lens device using a porous sintered metal plate. This has the effect of efficiently diffusing the directivity of the speaker.

[Brief explanation of the drawing]

1(a) and (b) are perspective views of an acoustic lens device according to an embodiment of the present invention, and FIG. 2(a) is a perspective view of a porous metal sintered plate of an acoustic lens device according to an embodiment of the present invention. Shape example f
Fig. 4 is a directional characteristic diagram of an acoustic lens device in an embodiment of an acoustic lens for various types of speakers; Figure 5 shows a cross section of another conventional acoustic lens device using a porous ceramic material. Sintered board. Name of agent: Patent attorney Toshio Nakao and one other person
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Claims (2)

[Claims] (1) One or more porous metal sintered plates with holes in the center are provided on the opening side of the speaker, and the plurality of porous metal sintered plates are stacked closely together or stacked with gaps between them. Acoustic lens device attached. (2) The acoustic lens device according to claim 1, wherein porous metal sintered plates with holes in the center are stacked on the opening side of the speaker in order of decreasing perforation area.