JPH012500A - Underwater piezoelectric wave transmitting/receiving sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to submarine seismic probes, fish finders, etc.
The present invention relates to an underwater piezoelectric wave transmitting/receiving sheet that emits sound waves or AR'i waves underwater toward a detected object, or receives reflected waves that are reflected back from the detected object.

Conventional technology (IK > Lead zirconate titanate, 41 piezoelectric materials such as polyvinylidene fluoride, polyvinyl fluoride, polyvinylidene chloride, polyvinyl chloride, nylon, etc. or 41 materials such as synthetic rubber and synthetic resin. A piezoelectric flexible sheet such as a piezoceramic composite made of ferroelectric ceramic particles such as lead titanate has an impedance of Xr, 4, which is close to the r1 impedance of water. Therefore, it is used as a piezoelectric transducer to receive acoustic waves propagating underwater.

In addition to this, there are also piezoelectric ceramic plates that are used as pressure:V + -landducers.

Furthermore, the piezoelectric flexible sheet and the piezoelectric ceramic plate can also be used as a wave transmitter that emits a wave or a TFL sound wave toward an object to be detected.

The conventional configuration of an underwater pressure transceiver sheet using a pressure 1σ plate such as a piezoelectric IIf flexible sheet or a piezoelectric ceramic is
As shown in the figure, a piezoelectric & a (
7) Provide electrodes b and c on the lower surface of l, and
A piezoelectric plate a is polarized in the thickness direction by applying a predetermined DC voltage to 1 liter, and this is immersed in water and an alternating voltage is applied to electrodes S and C to oscillate sound waves or ultrasonic waves. , tf, which extracts an output signal from between electrodes S and C and propagates it underwater.
I am trying to receive W waves.

<Problems to be Solved by the Invention> By the way, when the piezoelectric plate with the above configuration is used as a wave receiver, f1! under hydrostatic pressure; Waves are detected, and the sensitivity is determined by the piezoelectric constant g of the piezoelectric plate.
Determined by h. This gh is given by the following formula.

gh=g33+2g31 where the constant g ff3 is the pressure p in the thickness direction (polarization direction)
! The sensitivity to constant g3 and the pressure p2 in the clay surface direction (direction perpendicular to the polarization axis) are shown.

By the way, since g31 is a negative value, gh<g:+3, and in the conventional configuration, the value of gh is only the value of g33, and only low sensitivity can be obtained due to the pressure p2. could not.

This also occurs when used as a wave transmitter, and the piezoelectric constant dh is reduced due to water pressure from one side.

In the present invention, by removing the pressure p2 in the in-plane direction (direction perpendicular to the polarization axis) as much as possible, the constant g31 is made as low as possible, and the constant gh is approximated to g33, thereby achieving wave receiving sensitivity. We aim to provide a piezoelectric wave transmitting/receiving sheet for use in ice, which also increases the constant cth and improves wave transmission performance.
The target is

Means for Solving the Problems> The present invention provides that the outer periphery of a piezoelectric plate having double electrodes and polarized in the thickness direction is surrounded by a rigid frame at intervals, and This is characterized in that the plate and the frame are integrally connected by filling the plate with an elastic adhesive.

In the above configuration, the pressure p2 acting in the plane direction (direction perpendicular to the polarization axis) from the periphery of the piezoelectric plate is blocked by the 1% rigid body, and the influence on the periphery of the piezoelectric plate is reduced by one inch. removed. In addition, regarding the PI that acts in the thickness direction (polarization direction) of the piezoelectric plate, the 1 elastic contact and 71 material expand and contract in the I peak, preventing a decrease in wave transmission and reception sensitivity.

<Example> Regarding Figures 1 to 3, 1 is a synthetic rubber, lead zirconate titanate (PbTi03), +
Tough acid tA (P b T i 03 ) etc.ry>1
- Piezoelectric 'T' made of composite material mixed with E core powder
It is a rectangular piezoelectric plate l made of a l1lr sheet or a piezoelectric ceramic sintered body, polarized in the thickness direction, and electrodes 2.2 are formed on its upper and lower surfaces, and the electrodes 2.2 are formed by lead wires 3.3.
The signal can be extracted from between the two.

A rectangular rigid frame lO having approximately the same thickness as the piezoelectric plate l is fitted onto the outer peripheral edge of the piezoelectric plate l at a rectangular interval 11. The rectangular rigid frame lO is made of metal or plastic T.
A material with high rigidity (large longitudinal bone modulus) is used.

Next, an elastic adhesive material 12 made of elastic epoxy resin, silicone rubber, etc. is molded around the rigid frame lO including the periphery of the piezoelectric plate 1, and the space 11 is filled with the material. Thereby, the piezoelectric plate 1 and the rigid frame lO are integrally coupled. It is sufficient to fill the adhesive 12 only within the interval ll, and there is no need to mold the outer surface of the rigid frame lO and the central region of the piezoelectric plate 1.

On the other hand, with this configuration, a piezoelectric wave transmitting/receiving sheet is constructed, and even if a pressure p2 is applied from its periphery, it is blocked by the rigid frame 10, and the pressure p2 is applied to the outer periphery of the piezoelectric plate l.
2 will fall short.

To confirm this, in the next step, piezoelectric wave transmitting and receiving sheets were formed and their characteristics were compared.

That is, PbTi0z powder and chloroprene rubber were blended in a ratio of 40:60 (Ma 1%), a vulcanizing agent was added and mixed, and this was mixed at 200 kg/cm', 1
80℃.

Vulcanize under the conditions of 20m1n and further 100KV/cm
, Polarization was performed at 20° C. for 1 hour to obtain a piezoelectric plate 1.

And this is 70cm long - 30cm wide - 21m thick + 1
It is formed into a rectangular shape, and a metal frame lO is arranged around its periphery with a rectangular interval 11 of 1+sm, and it is constructed as shown in Fig. 2.3, and within and around the interval ll. , elastic epoxy resin (trade name: Eccogel 1385
-25) is supplied, and the elastic adhesive material 12 consisting of
Crosslinking was carried out under conditions of 24 hours or more, and the piezoelectric plate 1 and the frame 10 were joined to obtain a sample. This was then compared with the conventional configuration shown in FIG. 5, which consists of only the piezoelectric plate 1.

As a result, the piezoelectric constant dh of the conventional structure was 18.
8? Compared to this, the present invention has a value of 18.8, which is 1
An improvement of 2.0% was confirmed. This also means that the constant gh is improved in the reception characteristics.

Similarly, PbTi0:+ powder was mixed with Pb(T 1o
46Z ro, sl, ) 03 powder, but using a piezoelectric plate l formed by the same method as described above, the structure shown in Fig. 2.3 was constructed as shown in Fig. 5. A comparison was made with the conventional configuration. As a result, the piezoelectric constant dh of the conventional structure was 5.27, whereas the piezoelectric constant dh of the present invention was 5.87, an improvement of 11.4% was confirmed.

That is, it was found that the transmitting and receiving sensitivity of the present invention is four times the same.

In one example, there is a risk that the elastic adhesive 12 filled within one interval ll will harden slightly due to the pressure PI and hinder the expansion and contraction of the piezoelectric plate, but as shown in FIG. −1 of the body lO: This can be coped with by providing a pair of protrusions 10a, 10a on the lower surface so as to protrude inward, and lining the spacing 11 and the periphery of the piezoelectric plate l.

In addition, in the example shown in -, the piezoelectric plate l is constructed by forming electrodes 2.2 on the lower surface of L of a piezoelectric flexible sheet or piezoelectric ceramic sintered body, but as shown in FIG. It may be constructed by laminating piezoelectric plate layers 20 and 20 with internal electrodes 21 interposed therebetween. In this case, the internal electrode 2
1 to the outside, the piezoelectric plate layer 20
All you have to do is delete part of it.

<Effects of the Invention> As clarified by the above explanation, the present invention reduces the pressure in the plane direction that acts on the periphery of the piezoelectric plate, so that the constant g31 approaches zero in receiving waves. As a result, the constant gh is improved, resulting in high sensitivity, and in the case of wave transmission, the constant dh is increased, resulting in an excellent effect of improving wave transmission performance.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a piezoelectric plate l and a rigid frame lO used in an embodiment of the present invention, FIG. 2 is a partially cutaway bottom view, and FIG. 3 is a longitudinal sectional side view of the same. Moreover, FIG. 4 is a longitudinal sectional side view of the other side. Furthermore, FIG. 5 is a longitudinal sectional side view of a conventional example. 1; Piezoelectric plate 1O; Rigid frame 11; Rectangular interval 12; Elastic adhesive Applicant NGK Spark Plug Co., Ltd. Agent Patent Attorney Matsuura Teita No. 20 No. 4 Portion 5 Figure 1 - "-Zoku Neichi IE '*'''F 19868 JJ 5 [1 , -'-1 Dear Commissioner of the Patent Office (゛Pa'7゛[,
Display of matter Patent application rV462-158471? 1. Name of the invention: Underwater piezoelectric wave transmitting/receiving sheet 3, drawing 11: Relationship with the 11 cases Applicant address: 14-18, Mizuho-X Takatsuji-cho, Nasuya-shi Name (4
54) 13 Hon Tokushu Togyo Co., Ltd. Representative name: Suzukitei - [1 Agent: No. 460 Address: 801-3ff, Shijima 2nd Building, 11-11, Chiyo I113-chome, Naka-ku, So-shi (052) 331-141
5 Name (8404) Patent attorney Matsuura y Tabe 5, date of supplementary IF order Voluntary supplement 3, subject to supplement I Details - chootsu, ? +li Contents of +E 1) Specification, I: On the first line of page 4, it says "Exhibition~n". I am correcting it as ``Made ~ 16''. +'--□ 2) Specification 11: r(PbTi0
3), 4- Titanium lead (PbT 1o3)
bTi03]J. 3) Details +': ! I's r40 on page 6, line 16:
80 (volt) J, r80: 40
(vote) Revise J and 1E. 4) Details-) Page 7, line 10 says rl13.87 J, r LB, 87 , r 18.9X 10"C
/ Correct it as NJ. 5) Details, 1? 6) Correct the statement r5.27J on page 7, line 19 to r5.27X 10”C/NJ. 6) Correct the statement r5.87J on page 817, line 20 of the details to r
Correct as 5.87X 1O-12C/NJ.

Claims (1)

[Claims] 1) The outer periphery of a piezoelectric plate on which electrodes are formed on the upper and lower sides and polarized in the thickness direction is surrounded by a rigid frame at intervals, and an elastic adhesive is filled in the intervals. , an underwater piezoelectric wave transmitting/receiving sheet characterized by integrally combining a piezoelectric plate and a frame body. 2) The underwater piezoelectric wave transmitting/receiving sheet according to claim 1, wherein the piezoelectric plate is a piezoelectric flexible sheet. 3) The underwater piezoelectric wave transmitting/receiving sheet according to claim 1, wherein the piezoelectric plate is a piezoelectric ceramic plate.