JPH0418519B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmitter or receiver (transmitter/receiver) for generating or receiving ultrasonic waves used in an ultrasonic observation device or the like.

Conventionally, in this type of transducer, an excitation part 1 and a radiation plate 2, which is often a circular plate, are housed in a case 3 via an O-ring, and the excitation part 1 and radiation plate 2 are shown in FIG. It is fixed with adhesive A as shown, or
As shown in FIG. 2, they were fitted and joined using screws B. The mechanical compliance of the excitation section 1 and the mass of the radiation plate 2 combine to cause mechanical resonance and operate as a wave transmitter.

By the way, since the above-mentioned joint is a connection part of a mechanical resonance system, it is necessary that vibration transmission is stable. Therefore, as bonding conditions, advanced bonding characteristic values are required in terms of structural design, such as adhesive strength, screw strength, and parallelism on both sides, and strict control to prevent variations in the manufacturing process is also required.

Furthermore, in the above conventional structure, the excitation section 1 and the radiation plate 2
is rigidly connected, making it difficult to change the resonant frequency.

The present invention solves the above-mentioned drawbacks and provides a transducer having a structure in which stable connection and resonant frequency can be easily changed.

In the present invention, a liquid having compliance is filled between the excitation part and the radiation plate, and the compliance and the mass of the radiation plate constitute a mechanical resonance system.
Furthermore, the structure allows the resonant frequency to be changed by adjusting the amount of liquid filled.

Next, embodiments of the present invention will be described with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a cross-sectional view of a transducer according to the invention.

The transducer according to the present invention includes a vibrator 5 which is vibrated by an electrode plate 6 which receives a signal supplied via a cable 12, and which is connected to a case 3 via a lid 9, a stopper 11' and an O-ring 4'. A flange 7 that is held and closely contacts the vibrator 5 to transmit its vibrations.
, the radiation plate 2 held in the case 3 via the stopper 11 and the O-ring 4, the flange 7, and the radiation plate 2.
It is composed of oil 8 etc. contained in the. The cable 12 is fixedly held on the case 3 by a packing 14 and a tightening screw 13 to maintain watertightness. Reference numeral 10 denotes an oil plug, which is removed when filling the oil 8 and adjusting its amount.

Electrical energy is converted into mechanical energy in the excitation section consisting of the vibrator 5, flange 7, etc., and the oil 8 receives this mechanical energy and vibrates as one with the radiation plate 2, causing sound waves to be emitted from the surface of the radiation plate 2. radiated. Conceptual diagrams showing the operation of these vibration systems are shown in FIGS. 4a and 4b. FIG. 4a shows a cross-sectional view of the main parts of the transducer according to the present invention, in which 1 is an excitation section consisting of a vibrator 5, an electrode 6, and a flange 7. Since the center line part of the excitation part 1 (the center part of the vibrator 1) is a vibration node, its vibration amplitude a is zero. Also, the vibration amplitude c at the surface of the radiation part 2 is
Vibration amplitude b at the interface between the excitation part 1 and the oil 8
, usually c≈Qb. Here, Q
is the Q value of this vibration system. Figure 4b is a simplified version of Figure 4a in order to derive the equivalent circuits of Figures 5 and 6.
is a completely rigid body. The basic operation of this vibration system is as follows. The vibration of the excitation part 1 resonates due to the compliance of the oil 8 and the mass of the radiation plate 2, and the vibration of the radiation plate 2 is approximately Q times the Q value of the resonance system with respect to the vibration of the excitation part 1, and radiation Board 2
effectively generates sound waves in the medium that is in contact with it.

A more detailed equivalent circuit representation of these vibration systems is shown in FIGS. 5 and 6. FIG. 5 shows an equivalent composite transmission line. The vibration system shown in FIG. 4b has characteristic impedances Z ₀₅ , corresponding to the vibrator 5, flange 7, oil 8, and radiation plate 2, respectively.
It is represented by a coupled circuit of lines having Z ₀₇ , Z ₀₈ , Z ₀₂ and propagation constants θ ₅ , θ ₇ , θ ₈ , θ ₂ . FIG. 6 is a detailed view of FIG. 5, and the electrical parameters are shown with the numbers of each component attached to the suffix. Among them, C corresponds to the compliance of the component, and L corresponds to its weight. In Figure 6, the dominant constant for the resonance characteristics of the resonance system depends on the dimensions of each element, and is usually the compliance of the oil 8.
C ₈ and the square L ₂ of the radiation plate 2. (C ₅ , L ₅ , C ₇ ,
C ₇ , L ₈ and C ₂ can be ignored. ) The derivation of these equivalent circuits is as follows: Proceedings of the Acoustical Society of Japan 56, 10, 1-7-
2. This was carried out in accordance with the equivalent circuit of ``A method for measuring various constants of ceramics under uniaxial high pressure''. The resonance characteristic at this time is ω ² =1/2C ₈ L ₂ .

Next, the structure and operation of each element will be explained in detail.

The vibrator 5 is a cylindrical body made of an electrostrictive material such as titanium lead zirconate, and is bonded with a copper circular electrode plate 6 sandwiched therebetween. The vibrator 5 expands and contracts in response to electrical input applied via the electrode plate 6, and transmits vibration to the flange 7. The flange 7 is a disc made of stainless steel and is bonded to the vibrator 5 and transmits the vibration of the vibrator 5 to the oil 8. At this time, by selecting the physical parameters of the oil 8 and the radiation plate 2, the oil 8 is mechanically coupled to the radiation plate 2 and vibrates. At this time, the physical parameters of the oil 8 and the radiation plate 2 are selected so that resonance does not occur independently inside each of them. The oil 8 has a compliance property as a mechanical property. On the other hand, the radiation plate 2 has mass properties. These two elements combine to cause mechanical resonance. In addition, the dimensions such as the diameter and thickness of each oil 8 and the radiation plate 2 so that they do not cause resonance alone are as follows.
It may be approximately 1/4 or less of the wavelength at the frequency used.

Oil 8 uses silicone oil. Since the oil material only needs to be a liquid, if a material with a higher bulk modulus than alcohol is used, the compliance will equivalently increase and the size can be reduced.
Further, the radiation plate 2 is a circular plate made of aluminum alloy.
The surface in contact with the medium is treated with alumite for corrosion resistance. If a material such as brass with a higher specific gravity is used, the size can be further reduced.

The case 3 is a cylindrical container that houses the excitation section, oil 8, radiation plate 2, etc. and facilitates handling, and may be made of aluminum alloy. Its outer surface is alumite treated for corrosion resistance.

The O-ring 4 is filled with oil 8 as described above.
This is a sealing part to seal and maintain watertightness. Since the space between the flange 7 and the radiation plate 2 has a watertight structure with the O-ring 4, its vibration is rarely inhibited.

The lid 9 forms part of the case 3,
After inserting the excitation unit into the case 3 and processing the wiring, it is attached to the case 3 with screws so as to cover the case 3. Liquid packing is applied as a sealant to the joint surface between the case 3 and the lid 9.

The oil stopper 10 is for sealing the oil inlet hole for filling the liquid 8. After filling with oil, liquid seal is applied to the threaded part and screwed in.

The spat 11 is a rectangular chip that prevents the excitation part and the radiation plate from falling off, and the material is as follows:
Use elastic synthetic resin so as not to inhibit vibration. The spats 11 are provided at two locations at the upper and lower ends, respectively, and are screwed to the case 3 or the lid 9.

The cable 12 is a watertight cable.
The tightening screw 13 tightens the gasket 14 to seal the passage of the cable 12 in the case 3. Here, the excitation section is made up of a laminated structure in which the vibrator 5, the electrode plate 6, and the flange 7 are bonded together. Depending on the size of the excitation part, it is also possible to integrate a conical vibrator with electrodes formed by vapor-depositing a metal material on the outer circumferential surface in a headband shape. In this case, since there is no adhesive part, manufacturing becomes even simpler.

In FIG. 4, since b<c (radiation plate 2
(1/Q of the excitation amplitude), according to the present invention, the bonding conditions between the excitation part 1 and the radiation plate 2 are relaxed compared to FIGS. 1 and 2.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 7 shows a cross-sectional view of a transducer according to the invention. The transducer of this embodiment is based on the first embodiment, but has a structure in which the volume of oil 8 can be adjusted while the transducer is in use. Therefore, the matters explained in the first embodiment will be omitted, and the structural portion for adjusting the volume of the oil 8 will be explained.

Oil 8 communicates with oil sump 15 via connecting pipe 17. By moving the piston 16 in and out, the oil 8 is discharged and introduced into the case 3. When the predetermined volume is reached, the valve 18 is tightened. Similarly, position 19 is fixed. The positioner 19 is a rectangular chip to prevent the radiation plate 2 from falling off, and is made of a more elastic synthetic resin that does not inhibit vibration.
Install at two locations on the bottom edge and secure with screws. piston 17
A retainer 20 is also provided to prevent it from falling off. The oil sump may also be constructed from a bag made of elastic synthetic rubber or the like, and in this case the structure will be simpler. still,
As shown in connection with Fig. 6, the resonant frequency is (ω
=/√2 _{8 2} ) It changes approximately in inverse proportion to the square root of the amount of liquid. Although these embodiments have been described as a wave transmitter, since these operations are reversible, they can also be used as a wave receiver that receives sound waves and generates electrical signals. Furthermore, although the structure in which two radiating plates are disposed opposite to each other has been described, a transmitter having the same effect can also be realized with a structure using one radiating plate.

As explained above, by using a liquid in the mechanical resonance system, the present invention has the effect of stabilizing the transmission of vibrations at the portion where the vibrations are the greatest and facilitating manufacturing. Furthermore, by adjusting the volume of the liquid, it is possible to easily and continuously adjust the resonance frequency in accordance with usage requirements.

[Brief explanation of drawings]

Figures 1 and 2 are cross-sectional views showing the structure of a conventional transmitter, Figure 3 is a cross-sectional view showing the structure of the first embodiment of the present invention, and Figures 4 a and b are vibrations of the present invention. A conceptual diagram showing the operation of the system. FIG. 5 is an equivalent circuit diagram using an equivalent composite transmission line according to an embodiment of the present invention. FIG. 6 is an equivalent circuit diagram using constants according to an embodiment of the present invention. FIG. 3 is a sectional view showing the structure of a second embodiment. 1...excitation part, 2...radiation plate, 3...case,
4, 4'... O-ring, 5... Vibrator, 6... Electrode plate, 7... Flange, 8... Oil, 9... Lid, 10... Oil plug, 11, 11'... Stopper,
12... Cable, 13... Tightening screw, 14...
Packing, 15... Oil reservoir, 16... Piston,
17... Connecting pipe, 18... Valve, 19... Positioning, 20... Retention.

Claims (1)

[Claims] 1. An excitation section that serves as a vibration generation source; a liquid storage section that stores a liquid that transmits vibrations from the excitation section;
A transducer characterized by comprising a radiator that transmits the vibrations transmitted through the liquid to the outside, and an adjustment means that adjusts the amount of liquid stored in the liquid storage section and changes the resonance frequency. .