JPH0311898A - Wave transmitter-receiver - Google Patents

Abstract

PURPOSE:To obtain low frequency, high efficiency and high water pressure resistance by applying deflection resonance to a diaphragm and a piezoelectric member and constituting an acoustic tube with the diaphragm. CONSTITUTION:Plural slits 2 are provided radially in the middle of a cylinder 1 using an elastic material such as a metal or a synthetic resin and the member between slits is used as a diaphragm 3. The cross section of the diaphragm 3 is shaped rectangular to attain ease of sticking of a piezoelectric member 4. The piezoelectric member 4 is stuck to the inside of the diaphragm 3, the piezoelectric member 4 and the diaphragm 3 are connected so that the vibration direction of each diaphragm 3 by an electric signal is arranged and a terminal to receive an electric signal through a lead wire 6 is led out. An insulation sheath 5 protecting the structure comprising the cylinder 1, the slit 2, the diaphragm 3 and the piezoelectric member 4 is provided to the inner and outer faces and the end face of the structure from sea water electrically by means of mold. Moreover, the radial length of the cylinder 1 is set to nearly a half wavelength or one wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a transducer for use in sonar, and more particularly to a small-sized hydrophilic transducer having a low frequency, high moat rate, and high water pressure resistance.

[Conventional technology]

Conventionally, this type of transducer uses a cylindrical piezoelectric material 10 as an electromechanical transducer (hereinafter abbreviated as a switching element) as shown in FIG.
laminated as an insulating sheath on their outer or inner surface
It had a structure with 1.

In particular, in order to obtain a high transmitted sound pressure, the cylindrical piezoelectric material 1
The transmission frequency was set using resonance due to the respiratory vibration mode of 0.

In such a conventional transducer, a cylindrical piezoelectric material l
Since the rigidity of O is high, the resonance frequency tends to become high. Attempting to lower the resonant frequency has the drawback of increasing the outer diameter and weight. Furthermore, when used at a low frequency far from the resonant frequency, the power factor of one mechanical impedance deteriorates and the conversion efficiency decreases. As a result, high transmitted sound pressure cannot be obtained.

In order to obtain a low resonant frequency while reducing the rigidity of the electromechanical transducer, a piezoelectric material 2 is added to the diaphragm 20 as shown in FIG.
A transducer is known in which the diaphragm 20 is laminated together to cause flexural vibration and sound is transmitted from the outer surface of the diaphragm 20.

In this transducer, the inner surface of the diaphragm 20 is sealed with a sound case 22 in order to prevent a short-circuit phenomenon of sound waves with inverted phases. If the inner surface of the diaphragm 20 is made into an air chamber in order to completely prevent the short-circuit phenomenon, the diaphragm 20 has low rigidity and cannot be made highly resistant to water pressure.
It is also possible to fill the liquid 23 in order to increase water pressure resistance, and to emit sound waves from the inner surface of the diaphragm 20 in the sound case 22. However, since this sound wave has a low frequency, the thickness of the sound case 22 becomes large, resulting in a large and heavy transducer.

[Problems to be Solved] An object of the present invention is to provide a transducer that has a low frequency, high efficiency, high water pressure resistance, and is small and lightweight.

[Means for Solving the Problems and Effects] The transducer of the present invention is provided with a plurality of slits in the axial direction in the center of the cylindrical body excluding both ends, and the member between these slits is used as a diaphragm, This diaphragm has a structure in which a piezoelectric material is pasted on at least one of the inner and outer surfaces, and an insulating sheath is provided on the inner and outer surfaces and the end surfaces, and the axial direction of one cylinder has a length of approximately half a wavelength to one wave. are doing.

The structure according to the present invention obtains low-frequency resonance by utilizing flexural vibration, and the sound wave radiated from the inner surface of the diaphragm arranged in a cylindrical shape is generated by the diaphragm itself acting as a partition wall. By delaying the phase inside the tube and propagating it to the outside, short-circuiting of the sound waves radiated from the inner and outer surfaces is prevented, and a small and lightweight transducer with a high t@ rate is realized.

[Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view, partially in section, of an embodiment of the present invention. In the figure, a plurality of slits 2 are provided in a uniaxial direction at the center of a cylindrical body 1 made of an elastic material such as metal or synthetic resin. The member between each slit is used as a diaphragm 3. The diaphragm 3 has a reduced rigidity, and its cross section is shaped into a rectangle to facilitate attachment of the piezoelectric material 4.

A piezoelectric material 4 is pasted on the inside of the diaphragm 3, as shown in FIG. The diaphragm 3 and the piezoelectric material 4 are connected, for example, as shown in FIG. 2, so that the directions of vibration of each diaphragm 3 due to electric signals are aligned with each other, and a terminal for inputting an electric signal is drawn out by a lead wire 6.

The slit 2 can be filled with a flexible cushioning material, such as cork, in order to make the inside an air chamber or not to affect the resonance of the diaphragm. An insulating sheath 5 is provided by molding or the like on the inner and outer surfaces and end surfaces of the structure consisting of the cylindrical body 1, slit 2, diaphragm 3, and piezoelectric material 4 to protect the structure from seawater. ing.

When an electric signal having the same frequency as the flexural resonance of the diaphragm 3 to which the piezoelectric material 4 is attached is applied from the lead wire 6, the piezoelectric material 4 expands and contracts in the axial direction due to the piezoelectric effect. At this time, a shift in expansion and contraction in the axial direction occurs between the piezoelectric material 4 and the diaphragm 3, and this becomes a driving force for flexural resonance, causing both to move in the radial direction as indicated by the dotted line or the -dotted chain line in Fig. 3. It vibrates. This vibration causes
Sound waves with opposite phases are radiated to the inner and outer surfaces of the diaphragm 3. Among these sound waves, the sound waves radiated to the inner surface are caused by the side walls of the acoustic tube (
That is, since the diaphragm 3) vibrates in the same phase, it propagates to the upper and lower end surfaces without passing through the diaphragm 3. Due to the phase delay caused by the propagation time, the sound waves radiated to the inner surface are adjusted to have the same phase as the sound waves radiated from the outer surface. As a result, short-circuit phenomena of sound waves radiated from the inner and outer surfaces can be efficiently prevented. The width of the slit 2 is such that adjacent diaphragms 3 do not come into contact with each other during flexural vibration (approximately 0°1 to 1 m).
By making the insulating sheath 5 appropriately thick, it is possible to obtain a transducer with high water pressure resistance.

Note that the length of the cylindrical body 1 in the axial direction is set to approximately half a wavelength to one wavelength.

[Effects of the Invention] According to the present invention, since the diaphragm and the piezoelectric material are deflected and resonated, and the diaphragm constitutes the acoustic tube, a small and lightweight transmitter/receiver with low frequency, high efficiency, and high water pressure resistance can be achieved. You can get a wave device.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an embodiment of a transducer according to the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. The figures showing the piezoelectric material, FIGS. 4 and 5 are perspective views showing a conventional transducer.

Claims (1)

[Claims] A diaphragm formed between the slits by providing a plurality of slits in the axial direction of a cylindrical body, a piezoelectric material fixed to at least one of the inner and outer surfaces of these diaphragms, and a diaphragm and a piezoelectric material. A transducer comprising an insulating sheath covering the cylindrical body, and an axial length of the cylindrical body is about half a wavelength to one wavelength.