JPH02176487A - Underwater ultrasonic marker - Google Patents

Abstract

PURPOSE:To enable realization of a light-weight underwater ultrasonic marker and to enable investigation of the ecology of smaller fishes than usual by using a bimorph resonance-tupe ceramic vibrator. CONSTITUTION:A bimorph resonance-type ceramic vibrator 1 of a resonance frequency 50kHz, which is fixed to a container by a rubber elastic body 4, is connected to an electric circuit 8 by a lead wire 6 and a matching transformer 7. The electric circuit 8 makes the bimorph resonance-type ceramic vibrator 1 vibrate by a battery 9. An ultrasonic signal generated by the vibration of the bimorph resonance-type ceramic vibrator 1 is emitted outside through the rubber elastic body 4, and the ultrasonic signal is emitted in the direction of an arrow as a whole, since it is reflected by the container 5 accommodating the electric circuit 8, the matching transformer 7, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an underwater ultrasonic beacon that is attached to a target position underwater or to a moving object, such as a fish, and is used to know the location and location of the object.

(Technical Background of the Invention) Conventionally, in order to detect an underwater target, an oscillator that uses ultrasonic waves is usually attached to the target, and a corresponding receiving device receives the signal from the target's transmitter. By doing this, the existence of the target object is confirmed. When conducting ecological surveys of fish, a small ultrasonic transmitter, that is, an underwater ultrasonic beacon, is attached to the fish body to track and receive the ultrasonic signals. Therefore, the underwater ultrasonic beacon attached to the fish body should be as small as possible. It is desirable that

The size of this underwater ultrasound beacon is determined by the dimensions of the battery, electrical circuitry, and ultrasound transducer.

Furthermore, the size of the battery is determined by the magnitude of the output of the ultrasonic signal and the usage time, and the electric circuit is approximately determined by the elements used. The dimensions of an ultrasonic transducer are determined by its resonant frequency for similar types, and can be made smaller at higher frequencies. Although it is possible to miniaturize the ultrasonic element by increasing the frequency used, increasing the frequency increases the propagation loss of the ultrasonic signal in water and reduces the reach distance, which is not desirable. An object of the present invention is to provide an underwater ultrasonic beacon using a bimorph resonant ceramic transducer that enables miniaturization without damage.

(Summary of the Invention) FIG. 1(a) shows a conventionally used cylindrical vibrator, which utilizes a thickness imaging mode along the central axis. This requires a thickness of about 26 mm when the resonant frequency is 50 kHz. FIG. 1(b) shows a ring-type vibrator that utilizes a radial vibration mode. Resonance frequency 50k
Hz requires a diameter of 16 mm. Figure 1 (C)
shows a bimorph resonant ceramic resonator.
This uses the bending imaging mode. This vibrator resonates at a low frequency considering its small size, and the resonant frequency is 50kHz.
In this case, the thickness can be 1.4 mm and the diameter can be 7.3 mm.

Fig. 2 shows a method of fixing a bimorph resonant ceramic resonator. Fig. 2 (a) shows how to fix a bimorph resonant ceramic resonator 1 so as not to affect its vibration. Fixing base 3 using the vibration node 2 part
It is fixed at

This method has the disadvantage of a complicated structure and high production cost.

As shown in FIG. 2(b), the present invention is to mount the entire bimorph resonant ceramic resonator l using a rubber-like elastic body 4, for example, so as to have as little influence on the vibrations of the resonant ceramic resonator l as shown in FIG. 2(b). The method is to cover it and fix it to the container 5. In order to cover the entire bimorph resonant ceramic transducer, the part in the direction in which the ultrasonic signal is to be emitted is made as thin as possible, and the thickness of the part on the container side is approximately one quarter of the wavelength of the resonant frequency of the transducer. so that it becomes According to this method, the vibrator can be easily fixed to the container without using any particular fixing structure, and production costs can be reduced.

(Embodiment of the Invention) FIG. 3 shows a structural diagram of an embodiment using a bimorph resonant ceramic resonator having a resonance frequency of 50 kHz according to the present invention.

Rubber-like elastic body 4 (actually Toshiba silicon TSE38 B
A bimorph resonant ceramic vibrator l with a resonant frequency of 50 kHz is fixed to the container by a wire (using hardness JIS A 19) and is connected to an electric circuit 8 by a lead wire 6 and a matching transformer 7. The electric circuit 8 oscillates at δ0kHz using the battery 9, and drives the bimorph resonant ceramic resonator l. The ultrasonic signal generated by imaging the bimorph resonant ceramic transducer 1 is
Although it is radiated to the outside via the rubber-like elastic body 4, it is reflected by the container 5 that houses the electric circuit 8, matching transformer 7, etc., so the ultrasonic signal as a whole is mainly directed in the direction of the arrow shown in FIG. radiated. Rubber-like elastic body 4 in the example
The thickness is 0.5 mm in the direction of the arrow of the bimorph resonant ceramic vibrator l, ie, tl in FIG. 3, and 3 mm on the container side, ie, t2. Further, the thickness of the bimorph resonant ceramic vibrator used in this was 1.4 mm.

(Effect of the invention) Most of the conventional small underwater ultrasonic markers use a ring-shaped vibrator, and when the resonant frequency is 50kHz, the overall size of the container is approximately 20mm in diameter and approximately 110mr in length.
n, its weight in water was about 7 g. According to the invention, the diameter is 8 mm, the length is 30 mm, and it is underwater! The amount is 1.
8g, about 1/20th of the volume, about 4% of the weight in water
It can be reduced to 1/2. Test results have shown that not only can the performance be almost the same in terms of reach without sacrificing the output level of the ultrasonic signal, but the continuous usage time is also the same or longer.

As described above, according to the present invention, it is possible to realize an underwater ultrasonic marker that is unprecedentedly small and lightweight, and it is also possible to conduct ecological surveys of smaller fish than in the past.

[Brief explanation of the drawing]

Figure 1 illustrates the structure of an ultrasonic transducer; (&) shows a cylindrical type, (b) a ring type, and (c) a bimorph type. Figure 2 shows a bimorph resonant ceramic vibrator. The fixing method will be explained, and (a) shows a method using a shooting node, and (b) shows a method of fixing the vibrator by covering the entire vibrator with a rubber-like elastic body. FIG. 3 shows an embodiment of the invention.・Bimorph resonant ceramic resonator 2 ・Vibration node 3 ・Fixed base 4 ・Rubber-like elastic body 5 ・Container 6 ・Lead wire 7 ・Matching transformer 8 ・Electrical circuit 9. ・Battery

Claims (1)

[Claims] A. Underwater ultrasound beacon using bimorph resonant ceramic transducer. B. An underwater ultrasonic beacon in which the entire bimorph resonant ceramic vibrator is covered with a rubber-like elastic body, the rubber-like elastic body is attached to a container, and the bimorph resonant ceramic vibrator is fixed to the container. C. The thickness of the rubber-like elastic body that covers the entire bimorph resonant ceramic vibrator should be thinner in the direction in which the ultrasonic signal is to be transmitted, and thicker in the direction in which it is fixed to the container containing the electric circuit including the battery. The part is an underwater ultrasonic beacon fixed at a wavelength of about one-fourth of the resonant frequency of the bimorph resonant ceramic vibrator.