JPS58124399A - Ultrasonic wave transceiver - Google Patents

Abstract

PURPOSE:To obtain a sharp directivity and excellent pulse performance, by providing an oscillator placed at the center of a sticked type piezoelectric element, fixing the element to the case elastically with a buffer member and providing a thin plate and a horn having an opening. CONSTITUTION:The diaphragm 13 is fitted to a coupling shaft 12 having the sticked type piezoelectric element 11 at the center. The surrounding of the diaphragm 13 is elastically fixed at the inside surface of the case 17 with the buffer member 20 to suppress mechanical oscillation. The piezoelectric element 11 is elastically fixed to the bottom of the case 17 with the buffer member 21'. The thin plate 22 is placed in front of the diaphragm 13, and the thin plate 22 has a circular opening 21 taking a straight line passing through the coupling shaft 12 as a center and other opening 21' provided on a concentric circle of the opening 21. The case 17 and the thin plate 22 are inserted and held at the throat of a parabola 23. Thus, the ultrasonic wave transceiver having the sharp directivity and excellent pulse performance is obtained.

Description

[Detailed Description of the Invention] The present invention aims to provide an ultrasonic transducer using a bonded piezoelectric element, which has sharp directivity characteristics and good pulse characteristics. It is something to do.

In ultrasonic transducers used in air, Ef
Bonded elements made by Eden Ceramics are often used, and this is the resonance point for deflection imaging of the bonded elements.

(The mechanical impedance of air is significantly smaller than that of piezoelectric ceramics, so the bonded element is combined with the diaphragm to reduce the mechanical impedance. We are trying to reduce the

The structure of a conventional ultrasonic transducer is shown in FIG.

As shown in the figure, this involves penetrating and fixing a coupling shaft 2 to the center of a laminated piezoelectric element 1, attaching a diaphragm 3 to this coupling shaft 2, and attaching a diaphragm 3 to the laminated piezoelectric element 1.
The vibration nodes were fixed to the tip of a support base 4 with an elastic adhesive 5. 6 and 6' are terminals, Ryo is a case that covers and protects the bonded piezoelectric element 1, etc., 8 is a protective mesh attached to the through hole formed in the upper part of the case γ, and 9 and 9' are bonded pieces. Type piezoelectric element 1 and terminal 6゜6
This is the lead wire that electrically connects .

During wave transmission, a signal voltage is applied between the terminals 6 and 6', thereby causing the bonded piezoelectric element 1 to vibrate. Vibration plate 3
is driven by the bonded piezoelectric element 1 and emits ultrasonic waves into the air. When receiving waves, the diaphragm 3 vibrates due to the ultrasonic waves propagating in the air, an output voltage is generated in the bonded piezoelectric element 1, and an output is obtained between the terminals 6 and 6'.

Figure 2 shows the transmitted waveform when the ultrasonic transducer with the above structure is driven with multiple pulses, and the rise and fall are slow and the time is longer than 2 milliseconds. Met.

When using such conventional ultrasonic transducers and it is necessary to obtain measurement information in short time intervals, the signal received by the receiver has long rise and fall times, so The next signal was received, and accurate measurement information could not be obtained.Also, when transmitting and receiving waves using a single element, it takes a considerable amount of time to transmit and immediately become ready for reception. , measurement information could not be obtained at the time when it became possible to receive data.

Furthermore, if ultrasonic transducers using piezoelectric ceramics are required to have sharp directivity characteristics, the imaging plate, laminated piezoelectric element, and support stand for supporting the laminated piezoelectric element will become considerably large. There was a drawback. Even if a large diaphragm was used, the directional characteristics would not become sharp enough to make the sound source larger.

Even if an attempt was made to sharpen the directional characteristics using a horn, it was not easy to lower the mechanical Q and improve the pulse characteristics.

The present invention provides a diaphragm at the center of a bonded piezoelectric element,
In order to suppress mechanical vibration, the diaphragm and the bonded piezoelectric element are elastically fixed to the case using a cushioning material such as elastic rubber, and a thin plate with an opening and a horn are added to solve the above problems. By solving this problem, we were able to realize an ultrasonic transducer with sharp directional characteristics and excellent pulse characteristics.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view of this embodiment.

A conical diaphragm 13 made of metal or resin is attached to a coupling 11i112 arranged at the center of the disc-shaped bonded piezoelectric element 11. The periphery of the diaphragm 13 is covered with a buffer side 20 made of elastic rubber or the like to suppress mechanical vibrations.
It is elastically fixed to the inner surface of the cylindrical case 17. Further, the bonded piezoelectric element 11 is also elastically fixed to the bottom surface of the case 17 by a cushioning material 20' such as elastic rubber. A thin plate 22 is arranged in front of the diaphragm 13, and this thin plate 22 has a circular opening 21 with a straight line passing through the coupling shaft 12 as the center hole b, and the same as the opening 21.
It has another opening 21' provided at the circumference -I-.

The case 1a and the thin plate 22 are fitted and held in the throat of the parabolic horn 23. Lead wires 19 and 19' electrically connect the electrodes of the bonded piezoelectric element 11 and the terminals 16 and 16'.

Regarding the openings 21 and 21' of the thin plate 22, the directivity depends on the size and thickness of the bonded piezoelectric element 110, the size and thickness of the diaphragm 130, the center angle, the size of the cushioning material 20 and 20', etc. The shape where is the best changes, but
Typical examples are shown in FIGS. 4-16. These figures (A is a plan view, figure (B) is a cross-sectional view).

The wave transmitting/receiving operation of this embodiment is basically the same as that of the ultrasonic transducer shown in FIG.
It is shown in Figure 7. As is clear from this figure, the pulse rise and fall times are 0.3 milliseconds or less.

FIG. 18(A) shows the directional characteristics of the above embodiment, and FIG.
B) shows the directional characteristics of a comparative example with the same specifications as the example except that no thin plate was installed.

As is clear from this figure, the present invention not only reduces the sound pressure half angle, but also significantly reduces the side lobes, resulting in almost uniform directivity spatially (for example, downward, left and right). Characteristics are now available.

In addition, by integrally forming the case 17 and the thin plate 22, it becomes possible to obtain spatially more uniform directivity characteristics, reduce variations in the directivity characteristics, and also facilitate assembly and facilitate mass production. became.

Furthermore, if the integrally formed case 17 and thin plate 22 are made of a conductive material and connected to the ground, the noise resistance can be improved by -1.
- to do.

As shown above, the ultrasonic transducer of the present invention includes a bonded piezoelectric element in which a diaphragm is bonded to the center part, a case housing the bonded piezoelectric element, and a case surrounding the diaphragm. A first buffer material is attached so as to be in contact with the inner surface of the case, a second buffer material is attached to elastically fix the bonded piezoelectric element to the bottom surface of the case, and a second buffer material is attached in front of the 41 imaging plate. A thin plate having an open part is installed, and a horn to which the case and the thin plate are attached, and by holding the bonded piezoelectric element with first and second cushioning materials. Although it uses a horn, it has the features of sharp directional characteristics and good pulse characteristics.As a result, accurate measurement information can be obtained in a short time interval, so it is possible to use sound waves. It is extremely useful for ultrasonic applications that require sharp directivity characteristics, such as the distance side.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional ultrasonic transducer, and FIG. 2 is a diagram showing its pulse characteristics. FIG. 3 is a sectional view showing one embodiment of the ultrasonic transducer of the present invention, and FIGS. 4 to 16 show typical examples of thin plates thereof.
A) is a plan view, FIG. 17 is a cross-sectional view, FIG. 17 is a diagram showing the pulse characteristics, and FIG. 18 is a diagram showing the effect of the thin plate. 11... Bonded piezoelectric element, 12...
...Coupling shaft, 13...Diaphragm, 17...
・Case, 20.20'...Cushioning material, 21.2
1'...Opening, 22...11.Thin plate, 23.
·····Horn. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3/6 z#/2/'/6' Figure 4/41 Figure 5 Figure 6 (B) fβ) Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 17

Claims (6)

[Claims] (1) A bonded piezoelectric element with a diaphragm coupled to the center, a case for storing this bonded piezoelectric element,
a first cushioning material attached so as to be in contact with the periphery of the diaphragm and the inner surface of the case; and a second cushioning material elastically fixing the bonded piezoelectric element to the bottom surface of the case. An ultrasonic transmitter/receiver characterized by having a thin plate installed in front of the diaphragm and having an opening 1-1, and a horn in which the case and the thin plate are connected to each other. Wave equipment. (2) The diaphragm is conical, the bonded piezoelectric element is disc-shaped, and the top of the diaphragm is attached to a coupling shaft that is fixed through the center of the bonded piezoelectric element. An ultrasonic transducer according to claim 1, characterized in that: (3) An ultrasonic transducer according to claim 1ft4, characterized in that a plurality of thin plate gaps 11 are provided. (4) The ultrasonic transducer as set forth in claim 2 of the patent, characterized in that the thin plate has an opening at its center and its concentric circumference. (5) The four plates and the case are integrally formed!
An ultrasonic receiver according to claim 1. (6) The ultrasonic transducer according to claim 1, wherein the thin plate base is made of conductive material.