WO1999038027A1

WO1999038027A1 - Transmitter for ultrasonic wave emitter

Info

Publication number: WO1999038027A1
Application number: PCT/JP1998/000252
Authority: WO
Inventors: Shigeyasu Ishida
Original assignee: Shigeyasu Ishida
Priority date: 1996-12-06
Filing date: 1998-01-21
Publication date: 1999-07-29
Also published as: JPH10174189A; JP3564613B2

Abstract

In order to measure the depth or detect a shoal of fish under the sea water or under the water, ultrasonic wave is conventionally used, and a ceramic vibrator which utilizes the principle of electrostriction is used as an ultrasonic wave emitter in many cases. An ultrasonic wave emitter which has a transmitter using the ceramic vibrator and which has an improved emission efficiency is provided. A conventional ultrasonic emitter such as a so-called sounder which measures the depth to the sea bottom, a fishfinder which detects a shoal of fish emits an ultrasonic wave in one direction in the water, and a pulse wave is used. Therefore, various difficulties in using it such as avoidance of reflected waves caused by the emission in directions other than the aimed direction, etc., and hence it is very difficult to manufacture a large output sounder and fishfinder at present. Acoustic analysis of the transmitter using a ceramic vibrator has been carried out and the results of experiments which are satisfactory to some extent have been obtained. Hence a transmitter with increased output is provided based on the results.

Description

Description Transmitter for ultrasonic launch equipment Technical field

The present invention relates to a wave transmitting device that emits an ultrasonic pulse into a liquid such as seawater or underwater to detect sounding or detect a school of fish. More specifically, the present invention relates to a ceramic device using an electrostriction phenomenon called a piezoelectric element. This relates to a vibrator.

That is, ultrasonic sounding devices used in seawater or underwater, fish finders, etc., require a transmission device to emit ultrasonic waves, and this transmission device has conventionally been barium titanate zirconate titanate. Ceramic oscillators made of lead or the like have been widely used. The present invention relates to an ultrasonic wave emitting method for a wave transmitting device using the piezoelectric element. Background art

It has not been possible to say that the efficient use of these ceramic oscillators for ultrasonic emission has been thoroughly studied in the past, and even today, transmitters for sounding or fish detection are still in use. Although the output is small and the size is large, the overall weight is heavy and the size is large. Therefore, the improvement of this part was theoretically investigated.

A typical example of the structure of this type of conventional wave transmitting device will be described with reference to FIG. 3. If the surface of the ceramic vibrator (1) on the water depth side is generally made of a vibrating plate made of a plastic material such as nipple ( 2) is provided, and on the opposite side, a sheet such as Styrofoam (4) having closed cells is directly adhered to the back of the vibrator (1), and an air chamber (5) is provided at the back. . As a result, ultrasonic waves are emitted more from the side of the diaphragm (2) and hardly emitted from the opposite side of the polystyrene foam (4). The reason is that a considerable amount of ultrasonic waves are also emitted from the styrofoam (4) side, but since styrene foam has a myriad of closed cells, the ultrasonic waves are absorbed by these bubbles and fired to the rear side No, even if there is some leakage, it is absorbed here due to the air chamber (5) behind it and will not be fired to the rear.

With the above structure, the primary function as an ultrasonic wave transmitting device can be sufficiently performed. Conventionally, it was thought that the structure was almost completely satisfactory. However, if the styrofoam (4), air chamber (5), etc. are installed directly on the back of the ceramic vibrator (1) in order to prevent the emission of ultrasonic waves, the following problems can easily occur. I understand. In other words, in the structure shown above, the energy of ultrasonic waves emitted into the water is supposed to be largely emitted to the depth side and hardly emitted to the water surface side, so it seems that the purpose has been achieved for the time being. Considering the load balance of the emitted energy, the acoustic impedance on the diaphragm (2) side is relatively large, and the foam foam port (4) and the air chamber (5) on the opposing side are relatively large. The acoustic impedance of the ceramic vibrator (1) is extremely small, so the load balance on both sides of the ceramic vibrator (1) is very poor and more ultrasonic waves should normally be emitted on the diaphragm (2) side. Since the sound emission energy is emitted in inverse proportion to the acoustic impedance, most of the sound energy is consumed on the styrofoam (4) or air chamber (5) side rather than on the diaphragm side. Diaphragm (2) side Hardly ever fired.

Furthermore, if this part is considered as a structure that emits sound, the weight of the vibrating plate (2) with respect to the vibrator (1) is more than that of the styrofoam (4) and the air chamber (5). Because it is much heavier, the easiness of vibration against mechanical vibration is also emitted more toward the styrene foam (4) side in view of the law of inertia.

If the above is replaced with an electrical equivalent circuit instead of an acoustic circuit, the contents will be much easier to understand. If the acoustic circuit (A) of the transmitting device is replaced with an electrical equivalent circuit (B), the content of the ceramic oscillator (υ is electrically battery) Or, it is a power source (a) and is a source of energy, whereas the diaphragm (2), styrofoam (4), air chamber (5), etc. are electrically connected to the volume resistivity. (B), (c), and (d) are equivalent to loads connected in parallel with each other, and the acoustic energy emitted there is electrically consumed by the power. Is equivalent to

Analyzing the electrical circuit with such a configuration in terms of the impedance represented by the power supply and the load resistance connected to it, the electrical load impedances (b), (c), and (d) show that the load ( b) and the load (c) and (d) on the Styrofoam side are the same as being connected in parallel to the power supply (a), and the magnitude of the load impedance is the same as that of the diaphragm ( b) The styrofoam side is much larger and higher than the (c) (d) side. The result is. In this case, most of the electric power is consumed on the styrofoam (c) (d) side in inverse proportion to the magnitude of the load. In other words, most of the sound output is consumed on the styrofoam (c) and (d) sides. Further, from the viewpoint of the acoustic structure, it is clear that the weight of the styrofoam side is much smaller and lighter than that of the diaphragm side, so that it becomes more difficult to emit ultrasonic waves to the diaphragm side.

Therefore, the applicant has tried to improve the transmission device to improve the unbalance of the load and the acoustic structure. Disclosure of the invention

As can be understood from the above description, the same concept as that of an electric circuit is applied to audio equipment, and even if an attempt is made to apply a large load to a device with a poor load balance, no load is applied to a target location and only useless power is consumed. It is consumed in the equipment. What can be considered is to improve the load balance so that the acoustic impedance of the ceramic vibrator (1) on the styrofoam (4) (5) side is greater than the acoustic impedance on the diaphragm (2) side. Specifically, connect a material with a large acoustic impedance specific to the material. If you can't do that, place the largest possible value for them there. Specifically, a substance (3) having a high acoustic impedance may be bonded between the surface of the vibrator (1) on the styrofoam side and the surface of the styrofoam (4). The present invention has been developed from such a viewpoint.

However, in practice, the acoustic impedance of a diaphragm is quite large, and if the material exceeds that value, the material is considerably restricted. Furthermore, considering the conventional device, even if the acoustic impedance is not so large, even if it is at an intermediate stage between these and the conventional device, it may be sufficiently practical. Therefore, we decided to consider these intermediate stages. In other words, even if the object has the same acoustic impedance as the diaphragm, if the weight of the object provided there is made as heavy as possible and the weight on the diaphragm side is made as light as possible, on the diaphragm side by the law of inertia, Ultrasonic waves are emitted. This is a significant improvement in the apparent acoustic impedance, which is also a major improvement. Take one or both of the above measures It is understood that the efficiency of sound emission is greatly improved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a central sectional view showing a basic structure of a wave transmitting device for an ultrasonic wave emitting device according to the present invention. Fig. 2 shows the acoustic circuit diagram of the wave transmitting device used for the ultrasonic launch equipment and the equivalent electric circuit diagram. FIG. 3 is a central cross-sectional structure diagram showing a typical example of a conventionally used transmitting device for an ultrasonic wave emitting device. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described more specifically with reference to the accompanying drawings. The embodiment shown in FIG. 1 is a first embodiment for effectively implementing the present invention, and is an embodiment of the invention which simultaneously satisfies claims 1 and 2. Claims 1 and 2 are related to each other, and (1) is an ultrasonic emission source called a ceramic vibrator, which is generally a ceramic such as barium titanate or lead zirconate titanate. Ultrasonic waves are emitted using the principle of electrostriction in a disk-shaped element made of a material.

A disk-shaped vibrating plate (2) made of a nylon resin or an ABS resin is bonded to one side of the vibrator (1), that is, a deep side surface. The reason for using nylon or ABS resin is that the specific gravity is almost the same as water and the acoustic impedance is also close to water, so it is considered that ultrasonic waves can be effectively emitted into water. However, the material of this portion is not limited to this, and may be a plate material such as glass or stainless steel. The structure up to this point is basically the same as the conventional one, but the diaphragm should be as light as possible if possible.

Next, on the back side of the vibrator (1) opposite to the vibrating plate (2), a stainless steel block (3), which is as heavy as possible and has a large acoustic impedance, is attached. This is because the material of the object to be bonded preferably has a large material-specific acoustic impedance, and the greater the material-specific acoustic impedance, the more difficult it is to transmit ultrasonic waves in this direction. In this case, the shape of the back object (3) is not particularly specified, but generally the outer diameter is almost the same as the outer diameter of the vibrator (1) and the thickness is 1/4 λ which does not disturb the waveform of the ultrasonic wave to be emitted. Let X η be normal.

On the back surface, there is a foam of Styrofoam (4) with closed cells as before. -Paste the pieces. These points are the same as before, in order to completely block the ultrasonic waves emitted in the rear direction.

The above is the basic structure of the ultrasonic wave transmitting device according to the present invention, which is different from the conventional transmitting device in that the vibrator (the acoustic impedance which did not exist conventionally on the back of υ) is heavy in weight. Thus, the ultrasonic wave is emitted more toward the diaphragm (2) as described in the section of “Disclosure of the Invention.” Also, the ultrasonic wave is applied to the back surface of the vibrator (1). The material of the object (3) to be combined is the same ceramic material as other vibrators and other metals that are not easily corroded by seawater, such as stainless steel lump and copper lump, etc. at present. The reason is that the ceramic material is the second largest acoustic impedance material after the metal, but the ceramic material does not need to be the same material as the vibrator, and has the same high density and texture as the vibrator. If it is a dense material, a general porcelain material may be used. In general, the material of the second embodiment has a large acoustic impedance inherent in the substance and satisfies the factors for obtaining a large acoustic impedance.The invention of the second embodiment is exactly the same in appearance and the like as the first embodiment, but only The major difference from the first embodiment is that, as in the first embodiment, the weight of the object to be bonded to the back of the vibrator is ideally heavy and the acoustic impedance is large. Even if the dance is not large, if the acoustic impedance is slightly larger than the current diaphragm (2), seawater, etc., more ultrasonic waves will be emitted to the diaphragm side and the performance will be improved. If the performance is improved even if the performance is improved, it may be practically used depending on the frequency of the ultrasonic wave used and the purpose of the measurement. The lower limit of the body material is to be specified, and the lower limit is intended to be a material such as nylon or ABS resin that has the same or slightly higher acoustic impedance as the diaphragm (2) material. Therefore, when the materials are listed below, in addition to plastic materials such as nylon and BS resin, admixtures obtained by mixing these plastic materials with quartz powder are also included. Other materials include pottery, porcelain, glass, and depending on the method of use, in addition to these, for example, gypsum * cement etc. The reason for the expansion is that plaster-cement can be freely molded in the future, and it is expected that a transmitter with a considerably higher degree of freedom will be manufactured in the future. Industrial applicability

As described above, the present invention significantly improves the load balance of the acoustic impedance and increases the acoustic impedance on the styrene foam side as much as possible. Was completed.

This solves the problem that the image of an object in the deep sea or at a long distance is difficult to determine because it is vague in the past. Transmitters tend to be slightly heavier than conventional transmitters, but since they are used in water, their weight does not matter much. As explained above, it is of great significance that the acoustic impedance is greatly increased and the load balance is greatly improved. that's all

Claims

Scope of the request: Opposite to the surface of the ultrasonic transmitter used in seawater or underwater that transmits the ultrasonic wave of the ceramic oscillator in the transmitting device using the ceramic oscillator An object made of a substance such as a metal lump or a ceramic lump having a larger acoustic impedance than the acoustic impedance on the front side of the ceramic vibrator is bonded to at least the surface of the ceramic vibrator. A transmitting device for ultrasonic emission, characterized in that the acoustic impedance on the rear side is much larger than the actual acoustic impedance.

Metal or ceramic lumps on the surface of the ultrasonic transmitter used in seawater or water that is opposite to the surface on which the ultrasonic wave is to be emitted in the transmitter using a ceramic vibrator At the same time, the mass of the metal mass or ceramic mass attached to the back side of this ultrasonic transmitter is heavier than that of the diaphragm. From the viewpoint of the law of motion of the object, that is, the law of inertia, the inertia moment of the object attached to the back is larger than the inertia moment of the object constituting the diaphragm. Ultrasonic launching transmitter.