JPH03224399A - Piezoelectric ultrasonic vibrator - Google Patents

Abstract

PURPOSE:To attain broad band frequency equivalently by overlapping plural cylindrical piezoelectric vibrators with different diameter concentrically with gaps, connecting the bottom of the piezoelectric vibrator through the connection of a common bottom face member integrally and sending and receiving an ultrasonic wave from the bottom face member. CONSTITUTION:Cylindrical piezoelectric vibrators 1-3 with different diameter are overlapped concentrically with a gap and the bottom of the piezoelectric vibrators 1-3 is connected by a bottom member 4 in common to integrate the piezoelectric vibrators 1-3. Then outer wall electrode plates 1a-3a are interconnected to form one electrode and inner wall electrode plates 1b-3b are interconnected to form other electrode and an exciting source 5 is connected to the electrodes. The exciting frequency of the piezoelectric vibrators 1-3 is made slightly different and they are overlapped by properly selecting the heigh of the cylinders of the piezoelectric vibrators 1-3. Thus, the broad band of the frequency is attained equivalently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a piezoelectric ultrasonic transducer used in fish finders and the like.

[Prior Art] Currently, piezoelectric ultrasonic transducers using PZT (lead zirconate titanate) are widely used in the transducers of fish finders.

FIG. 3 is a perspective view schematically showing the configuration of a conventional piezoelectric ultrasonic transducer of this type, and in the figure (10) is a piezoelectric transducer;
(10a) and (10b) are electrode plates and (11
) is the excitation source.

This piezoelectric ultrasonic vibrator has electrode plates (10a) and (10b) provided on both sides of a piezoelectric vibrator (10), and an excitation source (11) is connected to each electrode plate (10a> and (10b)). Therefore, the piezoelectric phenomenon (pi) of direct voltage effect and reverse voltage effect
EZO electric transducer) is used.

In addition to PZT, the piezoelectric vibrator (10) can be made of quartz, single crystals such as lithium diobate (LiNbO9), or ceramics such as barium titanate, but they are easy to mold and have a high Curie temperature (300°). PZT is widely used because it is stable and has a large piezoelectric effect.

FIG. 4 is a diagram showing the frequency characteristics of the piezoelectric ultrasonic transducer shown in FIG. It has narrow excitation frequency characteristics.

[Problems to be Solved by the Invention] The conventional piezoelectric ultrasonic transducer described above is configured as described above, and its frequency characteristic has a single peak excitation frequency with a relatively narrow bandwidth. Therefore, for example, when used in a fish finder, there is a problem in that it is difficult to use signal technologies such as chirp signal technology and pseudo-noise signal technology that require wide excitation frequency characteristics.

The present invention has been made to solve this problem, and its purpose is to obtain a piezoelectric ultrasonic transducer with a simple configuration and a wide bandwidth.

[Means for Solving the Problems 1] A piezoelectric ultrasonic transducer according to the present invention comprises a plurality of cylindrical piezoelectric transducers each having a different diameter, which are stacked concentrically with a gap between them. The bottom surfaces of the piezoelectric vibrators are connected and integrated with a common bottom member, or cylindrical piezoelectric vibrators with different diameters and the common bottom member are simultaneously sintered and formed using the same material, and the outer wall of each piezoelectric vibrator is Each of the outer wall electrode plates is provided with an inner wall electrode plate, and each of the inner wall electrode plates is provided with an inner wall electrode plate, and the inner wall electrode plates are interconnected to form one electrode, and the outer wall electrode plates are interconnected to form the other electrode. An excitation source is connected to transmit and receive ultrasonic waves from the bottom member.

[Function] In this invention, by having the above-described configuration, the excitation frequencies can be superimposed on each piezoelectric vibrator with a slight difference, and it is possible to equivalently widen the frequency band. Become.

[Examples] Examples of the present invention will be described below with reference to the drawings. 1st
The figures show an embodiment of the present invention. FIG. 1(A) is a perspective view schematically showing the configuration of a piezoelectric ultrasonic transducer according to an embodiment of the present invention, and FIG. 1(B) This is a cross-sectional view of the vibrator in FIG. 1(A) taken along the χ-X plane. 3a) each piezoelectric vibrator (1
) to (3), piezoelectric outer wall electrode plates provided on the outer walls of (1b
) to (3b) are inner wall electrode plates provided on the inner walls of each piezoelectric vibrator (1) to (3), respectively, and (4) is an inner wall electrode plate provided on the inner wall of each piezoelectric vibrator (1) to (3).
1) to (3) a bottom member that shares the bottom part and integrates it;
(5) is an excitation source.

The piezoelectric ultrasonic transducer in this embodiment consists of cylindrical piezoelectric transducers (1) to (3) having different diameters stacked concentrically with a gap as shown in the figure. The bottoms of the vibrators (1) to <3) are connected and shared by a bottom member (4), and the piezoelectric vibrators (1) to (3) are fixed together. The outer walls of each piezoelectric vibrator (1) to (3) are covered with outer wall electrode plates (1a) to (3a), respectively, and the inner walls of each piezoelectric vibrator (1) to (3) are covered with inner wall electrode plates (1b) to (3a), respectively.
b), each of the outer wall electrode plates (1a) to (3a) is interconnected to form one electrode, and each inner wall electrode plate (1b)
- (3b) are interconnected to form the other electrode, and an excitation source (5) is connected to these electrodes.

By appropriately selecting the height of the cylinder, the excitation frequency of each piezoelectric vibrator (1) to (3) can be made slightly different for each piezoelectric vibrator (1) to (3). It is possible to overlap each other, and it is possible to equivalently widen the frequency band. FIG. 2 is a diagram showing the frequency characteristics of the excitation frequency of the piezoelectric ultrasonic transducer in this embodiment.

By adjusting the height of each piezoelectric transducer 1) to (3) and the gap between them, the frequency characteristics can be adjusted to create a piezoelectric ultrasonic transducer suitable for chirve signal technology and pseudo-noise signal technology. By utilizing this invention, various signal processing techniques can be used in fish finders.

Furthermore, in the above embodiment, a plurality of cylindrical piezoelectric vibrators with different diameters are stacked concentrically with a gap between them, and the bottoms of these piezoelectric vibrators are connected by a common bottom member to form each piezoelectric vibrator. However, cylindrical piezoelectric vibrators having different diameters and a common bottom member may be simultaneously sintered and formed from the same material.

[Effects of the Invention] As explained above, the present invention allows the excitation frequencies to be superimposed on each piezoelectric vibrator with a slight difference, and as a result, it is possible to widen the frequency band and eliminate chirp. It is now possible to use signal processing technology, such as signal technology and pseudo-noise signal technology, that could not be easily used in fish finders in the past, allowing fish finders to have higher sensitivity, lower power consumption, and smaller size. This has the effect of greatly contributing to the development of

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the frequency characteristics of a piezoelectric ultrasonic transducer in this embodiment, and Fig. 3 is a diagram showing the configuration of a conventional piezoelectric ultrasonic transducer. diagram showing,
FIG. 4 is a diagram showing the frequency characteristics of the conventional piezoelectric ultrasonic transducer shown in FIG. 3. (1) to (3) are piezoelectric vibrators, (1a) to (3) respectively.
a) is an outer wall electrode plate, (1b) to (3b) are inner wall electrode plates, (4) is a bottom member, and (5) is an excitation source.

Claims (2)

[Claims] (1). In a piezoelectric ultrasonic transducer, electrodes are provided on both sides of the piezoelectric vibrator and an excitation source is connected to these electrodes to obtain a direct voltage effect and a reverse voltage effect, multiple cylindrical piezoelectric vibrators each having a different diameter are used. A means for connecting the bottoms of these piezoelectric vibrators stacked concentrically with a gap therebetween by a common bottom member and using this bottom member as a wave surface for transmitting and receiving ultrasonic waves; are each provided with an outer wall electrode plate, and each inner wall is provided with an inner wall electrode plate, the outer wall electrode plates are interconnected to form one electrode, and the inner wall electrode plates are interconnected to form the other electrode. A piezoelectric ultrasonic transducer comprising: means for connecting an excitation source to the piezoelectric ultrasonic transducer. (2). 2. A piezoelectric ultrasonic vibrator according to claim 1, wherein said common bottom member is sintered and formed from the same material as said cylindrical piezoelectric vibrators having different diameters at the same time.