JP4443292B2 - Underwater microphone - Google Patents

Description

  The present invention relates to an underwater microphone that collects sound waves in water, and more particularly to an underwater microphone that can perform underwater sound pickup with a low mechanical impedance and presence.

  An underwater microphone is also called a hydro microphone, and since the water pressure increases with depth in water, it is designed to withstand the water pressure. As a transducer, a strain gauge attached in an air bag (see Patent Document 1), a dynamic unit (see Patent Document 2), and a piezoelectric type unit that is used most often (see Patent Document 2) Patent Document 3) is known.

Japanese Patent Publication No.51-23905 JP-A-9-247797 JP 2003-348695 A

  However, the conventional underwater microphones have low sensitivity because they are designed to withstand the water pressure by increasing the mechanical impedance regardless of the transducer. Therefore, even when it is not necessary to sunk deeply into the water (for example, in a swimming competition or underwater performance, it may be installed at a depth of about several tens of centimeters in the water), a realistic sound is collected. I couldn't.

  Accordingly, the problem to be solved by the present invention is an underwater microphone that is suitable for collecting sounds such as swimming competitions and underwater performances, and does not need to be deeply submerged in water. Is to provide.

In order to solve the above-described problems, the present invention provides an underwater microphone that collects sound waves in water, a non-directional condenser microphone unit that is waterproofed, and an elastic that is open at one end and closed at the other end. and a tubular body made of wood, the opening of one end of the tubular member sealingly fitted to the sound collection side having an acoustic terminal of the condenser microphone unit, in front of the acoustic terminal of the condenser microphone unit An air chamber having a predetermined volume is provided , and the cylindrical body is made of a thin synthetic resin material that can be deformed by a pressure change generated by sound waves in water, and the other end of the cylindrical body is closed by heat sealing. It is characterized by being.

  According to the present invention, since the mechanical impedance is low, underwater sound collection with a sense of reality can be performed. In addition, since the microphone unit is non-directional, a single unit can cover a wider range. Furthermore, since the configuration is extremely simple, it can be manufactured at low cost.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this. FIG. 1 is an exploded front view showing an underwater microphone according to the present invention, and FIG. 2 is a front view showing a use state in water.

As shown in FIG. 1, the underwater microphone includes a microphone unit 10 and a cylindrical body 20. In the present invention, the microphone unit 10, non-directional condenser microphone unit which can inexpensively obtain a small mold is used. In this example, an omnidirectional electret condenser microphone unit having an outer diameter of 5 mm used for a tie pin microphone or the like is employed.

  Since the microphone unit 10 is submerged in water, the microphone unit 10 is waterproofed. Applying a waterproofing agent (water repellent) is one effective method. However, a heat-shrinkable tube may be covered and shrunk by heating to impart waterproofness.

  As the cylindrical body 20, a tube having elasticity is used. A metal material may be used as long as it can be deformed with respect to a pressure change generated by an acoustic wave in water, but a thin synthetic resin tube is preferable in terms of ease of manufacture and cost. Uses a vinyl chloride tube having a wall thickness of about 0.2 mm, an inner diameter of 5 mm, and an axial length of 120 mm.

One end of the tubular body 20 is set to remain open, the other end may be hermetically closed fitted cap 21, but the present invention, thus the cylindrical body to heat Toshi Le without using caps It closes the other end of the 20.

  This underwater microphone is completed by airtightly fitting the opening 21 on one end side of the cylindrical body 20 to the sound collecting surface side having the acoustic terminal 10a of the microphone unit 10 via an appropriate sealing material. 20, a sealed air chamber AR having a predetermined volume is provided in front of the acoustic terminal 10a.

  FIG. 2 shows the underwater microphone installed in water. This underwater microphone is suitable for collecting sounds such as swimming competitions and underwater performances. For example, the microphone unit 10 is installed and used so as to be immersed to a depth of about several tens of centimeters from the water surface.

  Assuming that the pressure in the water is P1 and the pressure in the air chamber AR is P2, the pressure P2 in the air chamber AR changes in accordance with the change in the water pressure P1 generated by the sound waves in the water, and the pressure in the air chamber AR The microphone unit 10 converts the pressure change of P2 into an electric signal.

  Since this underwater microphone has a sufficiently low mechanical impedance, it is possible to collect underwater sound with a sense of presence. Moreover, since the microphone unit 10 is non-directional, it can collect a wide range of underwater sounds.

  In addition, when the cylinder 20 is thin as described above, the cylinder 20 may be crushed by water pressure and cannot be collected when submerged deeply in the water. However, in such applications, sensitivity is sacrificed. This can be done by using a highly elastic cylinder.

The front view which decomposes | disassembles and shows the underwater microphone by this invention. The front view which shows the use condition of the underwater microphone by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Microphone unit 10a Sound terminal 20 Tubular body 21 Opening part 22 Cap AR Air chamber

Claims (1)

In an underwater microphone that collects sound waves in the water,
Includes a non-directional condenser microphone unit waterproofing process is performed, and one end made of an elastic material that the other end is closed by being open cylindrical body, the condenser microphone openings at one end of the tubular body It is airtightly fitted to the sound collecting surface side having the acoustic terminal of the unit, and has an airtight chamber having a predetermined volume in front of the acoustic terminal of the condenser microphone unit ,
An underwater microphone , wherein the cylindrical body is made of a thin synthetic resin material that can be deformed by a pressure change generated by a sound wave in water, and the other end side of the cylindrical body is closed by heat sealing .

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