JP2757926B2 - Underwater transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved underwater transducer for exciting a vibrating section, and more particularly to an underwater transducer capable of eliminating unnecessary vibration modes or enhancing radiation surface vibration by exciting a base. About.

[0002]

2. Description of the Related Art Conventionally, when a low-frequency sound wave is radiated into water, a relatively small and light transmitter is disclosed in Japanese Patent Application No. Sho.
As disclosed in Japanese Patent Application No. -021148 and Japanese Patent Application No. 62-088811, a structure has been devised in which a vibration plate having a sound wave emitting surface has a bending vibration mode. However, the structure shown above has the following problems, and there is a problem that needs to be solved.

[0003] In an underwater transmitter / receiver, it is desirable that the transmitter and the receiver have the same structure. In this specification, the present invention will be described from the viewpoint of the transmitter.

[0004]

Problems to be Solved by the Invention For example, Japanese Patent Application No. 62-0
In 88811, the vibration mode is described only for the acoustic radiation surface. However, in practice, the base portion other than the radiation surface may have a vibration amplitude that cannot be ignored.
For this reason, an acoustic vibration wave is actually radiated also from the base portion, and this wraps around the output side from the acoustic radiation surface and interferes therewith, resulting in a problem that the radiation output is obstructed.

In the conventional structure, the radiation output is controlled only by the excitation of the vibrating section. Therefore, when the radiation output is increased, the excitation input voltage to the vibrating section is increased or the area of the vibrating section is reduced. It is necessary to increase the number of vibrating elements by increasing the size. Therefore, in order to avoid increasing the size of the vibrating section, it is necessary to rely only on the means for increasing the input voltage. An increase in the input voltage is restricted, for example, from the viewpoint of dielectric breakdown of a piezoelectric element as a vibration element to which the input voltage is applied. Therefore, conventionally, it has been practically difficult to increase the adjustment width for enhancing the output.

When a large number of transmitters are arranged and used, the transmission outputs interfere with each other as a result, which may cause variations in the transmitter outputs. In some cases, the drive side was damaged.

The present invention solves such a problem.
An object of the present invention is to provide an underwater transducer that can achieve the following objects. That is, the first purpose is to eliminate the vibration displacement of the base. A second object is to enable the output to be further enhanced than before. A third object is to make it easier to align the outputs from the transmitters when a large number of transmitters are arranged and used.

[0008]

The underwater transducer according to the present invention for achieving the above object is provided with a piezoelectric element laminate for exciting the base at the base. That is, in the present invention, in addition to exciting the excitation unit in the configuration of the underwater transducer in the same manner as in the past, the base unit can be excited simultaneously.
Here, it is effective and preferable that the piezoelectric element laminated body provided on the base portion is made to adhere the piezoelectric element to the base portion as a bimorph-shaped laminated body.

[0009]

When the exciting section is excited as before, an acoustic output can be obtained from the acoustic radiation surface, but at the same time, the base is vibrated.
Therefore, according to the present invention, the base portion is excited by the piezoelectric element laminate provided on the base portion. At this time, (1) the excitation mode of the base portion according to the present invention has a phase opposite to that of the conventional excitation mode. Excited to become
Adjusting the amplitude makes it possible to reduce the vibration displacement caused by both excitations to zero. This eliminates unwanted vibration modes at the base and eliminates unnecessary interference with the sound output from the sound emitting surface. (2) If the excitation mode according to the present invention is excited so as to be in phase with the vibration mode of the base part by the conventional excitation, the vibration displacement of the acoustic radiation surface can be further enhanced as compared with the case of the conventional excitation alone. . Moreover, this output enhancement
Since this does not increase the excitation input to the conventional vibrating section, the dielectric breakdown of the piezoelectric element does not occur. Further, when a large number of transducers are used in an array, the vibration of the acoustic radiation surface of each arrayed transducer is detected by a known method (for example, a method disclosed in Japanese Patent Application Laid-Open No. 61-866668), and the vibrations are aligned. By adjusting the excitation amplitude to the base of each transducer as described above, the outputs of the transducers can be made uniform. In this case, since the adjustment is performed by adjusting the excitation of the base without increasing the excitation input of the excitation unit, the drive side circuit is not damaged by the excitation.

A stacked body in which a large number of piezoelectric elements are stacked in, for example, the left and right directions is further stacked in the up and down direction, and a voltage is applied thereto, whereby polarization is generated in each of the piezoelectric elements as shown in FIG. 2, for example. This is known as a bimorph element, in which case, for example, when the upper stack expands, the lower stack operates to contract, thereby acting as an efficient piezoelectric effect element. It has been known. In the present invention, if the piezoelectric element is brought into close contact with the base as a bimorph-like laminate, it is possible to give the vibration of the "sludge" of the plate to the base using the highly efficient bimorph piezoelectric effect, that is, a bending mode. Thus, the three objects of the present invention can be efficiently achieved with a relatively small excitation input different from the conventional excitation.

[0011]

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the sound radiating surface 1 vibrates in a vibration mode having a vibration displacement as shown by an arrow due to vibration excitation by applying an alternating voltage to the vibrating portions 14a and 14b. At this time, the base 3 vibrates in a vibration mode as indicated by a downward arrow. As an example, in order to cancel the vibration of the base 3, which is the first object of the present invention, the piezoelectric element laminate 5 is bonded to the base 3 via the insulator 7. At this time, the insulator 7 is desirably a ceramic or the like having a small vibration loss because it is necessary to strongly transmit the vibration. The configuration of the piezoelectric element laminated body 5 used here is such that the piezoelectric elements 53, 54, 55, 56,... Polarized in + and-as shown in FIG. The upper electrode is the lead wire 51
The electrode taken out from the lower side is connected to the lead wire 52. When an alternating voltage is applied between the lead wires 51 and 52 in this manner, bending vibration is performed in a vibration mode as indicated by an arrow. At this time, each of the piezoelectric elements 53, 54, 5
It is important that the insulating plate 7 and the like 7 are firmly bonded to each other with a hard epoxy resin or the like. The piezoelectric element laminate 5 works to cancel the vibration if it is made to vibrate in a phase opposite to the vibration mode shown downward in FIG. 1, and if the vibration amplitude is adjusted, the vibration of the base 3 will be as the first purpose. Becomes zero. Also, at this time, if the direction of the alternating voltage applied to the lead wires 51 and 52 is reversed, that is, if the phase is reversed, the vibration will be in the opposite phase to the arrow shown in FIG. 2, and the vibration of the base 3 in FIG. Therefore, the vibration displacement of the acoustic radiation surface 1 in FIG. 1 is enhanced. This operates to achieve the second object. By controlling the voltage applied to the lead wires 51 and 52 in this state, the amount of vibration displacement of the acoustic radiation surface 1 can be controlled, so that the third object can be achieved.

Although the piezoelectric element laminate 5 is illustrated on the outside in FIG. 1, that is, on the lower side in FIG. 1, the same effect can be obtained even when the piezoelectric element laminate 5 is divided and adhered on the inside, that is, on the upper side of the base 3 in FIG. .

FIG. 3 shows, as an example applied to the second object, experimental data on the linearity of the acoustic radiation level when the piezoelectric element laminate 5 is not driven and when it is driven. From this figure, it can be seen that the effect of driving the piezoelectric element laminate 5 is about 2 d.
It can be seen that B is enhanced. The vertical axis in FIG.
The magnitude of the acoustic emission sound pressure at a point spaced a distance of 1m from the sound source of the wave transmitter, the sound pressure 1MyuP _a a (P _a Pascal) 0d
This is expressed by dB when B is used.

[0014]

According to the present invention, by controlling the amplitude and the phase of the piezoelectric element laminate 5 which is brought into close contact with the base 3, the vibration of the base 3 which is the first object can be reduced to zero or the first vibration can be reduced. There is an effect that the vibration displacement of the sound radiation surface 1 as the second purpose can be enhanced and the vibration displacement as the third purpose can be controlled.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is a sectional view of a piezoelectric element laminate according to one embodiment of the present invention.

FIG. 3 is an experimental value of a relationship between a voltage applied to a piezoelectric element and an acoustic radiation level.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sound emission surface, 1a ... Boundary area, 2 ... Exciting part, 2a ... Exciting element element, 3 ... Base part, 3a ... Mounting part, 5 ... Piezoelectric element laminated body, 51, 52 ... Lead wire, 53, 54, 55, 56: piezoelectric element, 7: insulator

Continuation of the front page (72) Inventor Koji Meguro 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01S 7/521 H04R 1/44 330

Claims (2)

(57) [Claims] An exciter, an acoustic radiation surface, and a base,
The vibrating part has a configuration of a piezoelectric element laminate, and is attached to an end of a flexible sound emitting surface, and the end has a cross section connected to both ends of a rigid base. do it,
An underwater transducer in which a piezoelectric element laminate for exciting a base is provided at the base, wherein the base is provided with a piezoelectric element laminate that excites the excitation unit to obtain an acoustic output from the acoustic radiation surface. 2. The underwater transducer according to claim 1, wherein the piezoelectric element laminate provided on the base has a piezoelectric element adhered to the base as a bimorph-like laminate.