JPH04139500A - Acoustic pipe of microphone - Google Patents

Abstract

PURPOSE:To realize a microphone in a shape corresponding to a purpose by constituting the acoustic pipe of the microphone by using a net and an adhesive tape and deforming the acoustic pipe into an optional thin and lightweight shape. CONSTITUTION:The microphone 11 consists of an electret type microphone unit 12, the acoustic pipe 13 which contains this microphone unit 12 in one axial end part, and a microphone case 14 which covers the outer peripheral surface of this acoustic pipe 13. The acoustic pipe 13 consists of a thin net body 22 of metal like stainless steel, synthetic resin, etc., stuck on one surface of the both-sided adhesive tape 21 which is made of a paper or synthetic resin film sheet and have adhesives applied on both surfaces of its base material, and acoustic resistance materials 23 and 24 like cloth or nonwoven fabric stuck on the other surface of the both-sided adhesive tape 21. Consequently, the desirable size and shape of the microphone are easily set and the microphone in the shape matching the purpose can be manufactured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a super-directional microphone, and more specifically, it is attached to the tip of a microphone unit and has a structure of an acoustic tube so as to obtain narrow directivity. Regarding.

[Conventional technology]

Various attempts have been made in the past to narrow the directivity by attaching an acoustic tube (interference tube) to the tip of a microphone unit. The length of such a sound tube is determined by the lowest frequency at which a specific directivity is desired, so the side wall of the sound tube should be of an appropriate size so that the length of the sound tube becomes acoustically short when the frequency is high. An acoustic resistance material having an appropriate acoustic resistance is pasted to cover the opening.

That is, to explain the configuration of a conventional acoustic tube with reference to FIG. 5, an acoustic tube 1 made of metal such as aluminum or brass or synthetic resin is cut or has an opening 2 of an appropriate size on its side surface to take in sound waves. A plurality of holes are formed by injection molding at predetermined intervals in the axial direction, and an acoustic resistance material 3 such as cloth, net, or nonwoven fabric having an appropriate acoustic resistance is bonded with adhesive or double-sided tape to cover these openings 2. are doing.

A microphone unit 3 is installed inside the opening at one end of this acoustic tube 1.
The sound pickup section is positioned so that the

It has also been proposed that a second microphone unit 3 is mounted inside the sound tube 1 to obtain a high wind noise prevention effect and to obtain directivity in the mid-low range that exceeds the characteristics originally possessed by the microphone unit. There is.

[Problem to be solved by the invention]

As mentioned above, the openings 2 are formed by cutting, injection molding, etc., but forming a plurality of openings 2 of a predetermined size and at a predetermined interval in a tubular body not only requires skill, but also requires a lot of skill around the openings. It is necessary to pay close attention to the processing of Paris. In order to simplify the process of forming the opening, it has been proposed to form a long hole extending in the axial direction in the side wall of the acoustic tube, but the problem with such a long hole is that the center of the long hole tends to open during processing. There is a point.

Furthermore, if a microphone unit with a large diameter is used, the low frequency reproduction limit can be extended and the S/N ratio can be improved. The method of locating the sound section has the disadvantage that a microphone unit with a diameter larger than the inner diameter of the acoustic tube cannot be used. For this reason, when there is a limit to the outer diameter dimension, the problem in design is how to reduce the wall thickness of the acoustic tube. In particular, when an acoustic tube is constructed from a metal tube, a drawn tube made of aluminum or the like is usually used, but its wall thickness is about 1 m, and it cannot be made any thinner than that.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a microphone sound tube which has a simple structure, is light in weight, and can be manufactured at a low cost without any processing such as machining or injection molding.

[Means to solve the problem]

The acoustic tube of the microphone of this invention is made up of a sheet-like adhesive tape provided with openings for setting directivity, and a net made of metal, synthetic resin, etc. stuck to the adhesive surface of this adhesive tape. The net body is characterized in that it is bent into a hollow body shape to constitute an acoustic tube.

This invention is also characterized in that the adhesive tape is composed of a double-sided adhesive tape having an adhesive surface on the other side, and the acoustic resistance material is attached to the other side of the double-sided adhesive tape so as to cover the opening. It is something.

[For production]

Openings for adjusting directivity are provided in the adhesive tape, and since the openings can be punched while the adhesive tape is flattened, the desired size and shape can be easily set. Since the net is attached to this adhesive tape, the opening will not be deformed, and the net can be easily formed into any shape, making it possible to manufacture microphones of any shape depending on the purpose. Furthermore, since it can be constructed from a mesh and adhesive tape, it is also possible to create an extremely thin and lightweight acoustic tube.

Further, even when the acoustic resistance material is provided so as to cover the opening by using this adhesive tape as a double-sided adhesive tape, the acoustic resistance material can be provided with a simple pasting operation.

〔Example〕

The present invention will be described below with reference to embodiments shown in FIGS. 1 to 4b.

FIG. 1 shows a super-directional microphone 11 using an acoustic tube according to a first embodiment of the present invention, and this microphone 11 includes an electret-type microphone unit 1.
2, an acoustic tube 13 that accommodates the microphone unit 12 in one axial end thereof, and a microphone case 14 that covers the outer peripheral surface of the acoustic tube 13.

As shown in exploded view in FIG. 2a, the acoustic tube 13 includes a double-sided adhesive tape 21 having adhesive applied to both sides of a base material made of paper or a synthetic resin film sheet, and one side of the double-sided adhesive tape 21. The double-sided adhesive tape 2I is attached to a thin mesh body 22 made of metal such as stainless steel or synthetic resin, for example, about #100 mesh, and has a size approximately equal to the size of the double-sided adhesive tape 2I. 23.24 Acoustic resisting material, such as a cloth or non-woven fabric, attached to the other side.
It is made up of spikes. The double-sided adhesive tape 2I has two elongated holes 25 corresponding to the openings 02 of the conventional example described above, and two round holes 26 for communicating with the opening 15 formed at the peripheral edge of the microphone unit I2. There is. The acoustic resistance material 23 is sized to cover each long hole 25 of the double-sided adhesive tape 21, and the acoustic resistance material 24 is sized to cover each round hole 26.

Such an acoustic tube 13 is manufactured by first punching a long hole 25 and a round hole 26 at preset positions in the double-sided adhesive tape 21;
Next, the net body 22 is attached to one surface.

Next, the acoustic resistance material 23 is attached to the other side of the double-sided adhesive tape 21.
is pasted so as to cover each elongated hole 25, and the acoustic resistance material 24
is pasted so as to cover each round hole 26. After the mesh body 22 and the acoustic resistance material 23° 24 are attached to the double-sided adhesive tape 21 in this way, a cylindrical shape whose circumferential surface length is approximately equal to or slightly shorter than the length of the mesh body 22 is formed. The integrated double-sided adhesive tape 21, mesh body 22, and acoustic resistance material 23, 24 are wound around the jig 31, and both longitudinal edges are aligned, and this seam is adhered with a single-sided adhesive tape 27. After the joints are bonded, the jig 29 is removed to complete the hollow cylindrical acoustic tube 13. This acoustic tube 13 may be inserted into the microphone case 14. In FIG. 1, a cap 28 is made of a net similar to the net 22, and is inserted and fixed in advance into the tip of the microphone case 14 in the direction of the sound collection axis.

In this way, the acoustic tube 13 is formed into a tubular shape mainly by the net body 22, so it is lightweight and can be easily deformed into any shape, and the opening is formed in the sheet-like double-sided adhesive tape 21. Therefore, it can be accurately formed into the desired size and shape. Moreover, the acoustic resistance material 23.
24 can be attached by simply pasting it on one side of the double-sided adhesive tape 21, making it possible to manufacture a thin-walled acoustic tube extremely easily.

FIG. 3 is a graph showing the frequency response characteristics of a microphone using the acoustic tube 13 made in this way.
The characteristics when tilted by 90 degrees are shown by the dotted line b, and the characteristics when tilted by 180 degrees are shown by the dashed line C. As you can see from this graph, super directivity can be obtained from low to high frequencies.

Figures 4a and 4b show another embodiment of the sound tube of the present invention in which it is applied to a panel-mounted microphone, and such a microphone can be used, for example, as a hands-free transmitter for a car phone. Used as a microphone. That is, the microphone unit 32 is attached to one longitudinal end of the rectangular flat board 31 with its sound collection port facing the other longitudinal end of the board 31 . A substantially semi-cylindrical acoustic tube 33 is attached to the substrate 31 . Similar to the above-described embodiment, this acoustic tube 33 includes a rectangular double-sided adhesive tape 34, a net 35 stuck to one side of the double-sided adhesive tape 34, and an acoustic resistance material 3.
It consists of 6. Approximately the center of the double-sided adhesive tape 34,
That is, when the semi-cylindrical shape is formed, a long hole 37 is formed in a portion located near the top thereof so as to extend in the longitudinal direction. The acoustic resistance material 36 is provided so as to cover only the long hole 37 portion. The acoustic tube 33 housing the microphone unit 32 is covered with a microphone case 38 made of a wire mesh or punched metal that is transparent to sound waves. The microphone 39 configured in this way and supported on the substrate 31 is arranged such that the end of the sound tube 33 opposite to the end where the microphone unit 32 is located is positioned toward the sound source, that is, toward the mouth of the person speaking. and is fixed in a mounting opening 42 provided in a mounting board 41.

This makes it possible to cut out engine noise and ambient noise and ensure that only the voice of the caller is captured.

In each of the above-mentioned embodiments, an acoustic resistance material is provided, but the mesh body is also a type of acoustic resistance material, and if the acoustic resistance of the mesh body is sufficient, it is sufficient to simply form large openings in the double-sided adhesive tape. good. In this case, since adhesion on the other side is not necessary, it goes without saying that a single-sided adhesive tape may be used.

〔Effect of the invention〕

As described above, since the acoustic tube of the microphone of the present invention is composed of a mesh and adhesive tape, it can be constructed extremely thin and lightweight, and can be deformed into any shape without the need for machining or molding. , it is possible to provide microphones of various shapes depending on the purpose. Furthermore, since the adhesive tape is provided with openings for adjusting the frequency, the holes can be punched while the adhesive tape is flat, and the desired size and shape can be easily and accurately set. Since the mesh is attached to this adhesive tape, the opening will not be deformed.

In addition, if the mesh alone does not have enough acoustic resistance, you can use double-sided adhesive tape to cover the opening with an acoustic resistance material such as cloth or non-woven fabric. Acoustic resistance material can be provided with.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a microphone using an acoustic tube according to a first embodiment of the present invention, FIG. 2a is an exploded perspective view showing the configuration of the acoustic tube, and FIG. 2b is a flat acoustic tube. FIG. 2c is a perspective view showing an example of a means for forming a component into a tubular shape, FIG. 2c is a perspective view showing a completed acoustic tube, FIG. 3 is a graph showing the frequency response characteristics of a microphone using this acoustic tube, and FIG. The figure is a longitudinal sectional view showing another embodiment of the invention.
FIG. 4b is a cross-sectional view thereof, and FIG. 5 is a vertical cross-sectional view showing an example of a conventional acoustic tube. In the drawing, 11.39 is a microphone, 12 is a microphone unit, 13.33 is a sound tube, 21.34 is double-sided adhesive tape, 22.35 is a mesh body, 23.24.36
25, 37 are long holes, 26 are round holes, and 27 is one-sided adhesive tape. Patent Applicant Audio Technica Co., Ltd. Agent Patent Attorney Takuya Ohara Figure Frequency (Hz) Figure 20 Figure 2b Figure 2c

Claims (2)

[Claims] (1) It has a sheet-like adhesive tape with openings for setting directivity, and a net made of metal, synthetic resin, etc. stuck to the adhesive surface of this adhesive tape. An acoustic tube of a microphone characterized in that a mesh body is bent into a hollow body shape to constitute an acoustic tube. (2) The adhesive tape is composed of a double-sided adhesive tape having an adhesive surface on the other side, and an acoustic resistance material is attached to the other side of the double-sided adhesive tape so as to cover the opening. The sound tube of a microphone according to claim 1.