JPS63191956A - Method for supporting ultrasonic vibrator - Google Patents

Abstract

PURPOSE:To reduce vibrations of the reverse surface of an ultrasonic vibrator and to improve conversion efficiency by providing a gap between the reverse surface of the ultrasonic vibrator and the top surface of a base and supporting the vibrator on the base mechanically and acoustically. CONSTITUTION:The ultrasonic vibrator 10 is supported mechanically on the base 20 so that the surface of a lower electrode 10c is at a distance l from the top surface of the base 20 and the surface of the electrode 10c is parallel to the top surface of the base 20. The ultrasonic vibrator 10 vibrates vertically by being supplied with an electric signal to radiate ultrasonic waves vertically from the surfaces of the electrodes 10b and 10c. At this time, the majority of the ultrasonic wave which is radiated from the surface of the reverse electrode 10c and incident on the top surface of the base 20 is reflected by the top surface of the base 20 because of a difference in acoustic impedance between air and the base 20. In this case, the ultrasonic wave which is reflected by the top surface of the base 20 and incident on the surface of the electrode 10c is opposite in phase from the ultrasonic wave which is radiated by the vibrations of the surface of the electrode 10c. Consequently, the amplitude of the surface of the electrode 10c is reduced and the ultrasonic wave which is radiated is reduced, so the efficiency of electricity-ultrasonic wave conversion is improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is based on an ultrasonic transducer that converts an electric signal into an ultrasonic wave and radiates the ultrasonic wave, or converts an incident ultrasonic wave into an electric signal. The present invention relates to a method for supporting an ultrasonic transducer on a stand.

(Prior art) Conventionally, this type of support method involves fixing the lower surface of an ultrasonic transducer that vibrates perpendicularly to the opposing north and lower surfaces to a base directly or attaching it to the base via a rubber plate. There is a method in which the vibrator is supported on a base by fixing it to the base. (July 20, 1973, Ultrasonic Technology Handbook, published by Nikkan Kogyo Shimbun, pp. 342-344) (Problems to be solved by the invention) However, in the above conventional support method, Since some of the vibrations of the ultrasonic vibrator propagate to the base either directly from the bottom of the vibrator or via a rubber plate, this ultrasonic vibrator can be used by converting electrical signals into ultrasonic waves. When the converted ultrasonic wave is used on the transmitter side to radiate, the output of the ultrasonic wave emitted from the top surface of the transducer decreases, and the ultrasonic transducer converts the incident ultrasonic wave into an electrical signal. When used on a receiving side that converts and outputs the converted electrical signal, there is a problem that the electrical signal output decreases. That is, electricity-
There is a problem of poor conversion efficiency in ultrasonic conversion and ultrasonic-to-electrical conversion.

The present invention has been devised in view of the above-mentioned problems, and its purpose is to provide a method for supporting an ultrasonic transducer that improves the above-mentioned conversion efficiency.

Means for Solving the Problems) In order to solve the above problems and achieve the objects of the present invention, the present invention has an ultrasonic transducer that vibrates in a direction perpendicular to an upper surface and a lower surface that face each other. A method for supporting an ultrasonic transducer on a base, the lower surface of the ultrasonic transducer being opposed to the upper surface of the base, and the lower surface of the ultrasonic transducer and the upper surface of the base being The ultrasonic transducer is mechanically supported on the base by a supporting member so as to provide a gap therebetween, and the ultrasonic transducer is radiated from the lower surface of the ultrasonic transducer and reflected on the upper surface of the base. The ultrasonic transducer is acoustically supported by the ultrasonic wave incident on the lower surface of the base.

(Function of the invention) As in the above-mentioned present invention, the ultrasonic transducer is mechanically and acoustically supported on the base by providing a gap between the lower surface of the ultrasonic transducer and the upper surface of the base. As a result, since there is a large difference in the acoustic impedance of the medium such as air that is present in the gap and the acoustic impedance of the base, most of the ultrasound waves emitted from the bottom surface of the ultrasonic transducer as it vibrates. The reflected ultrasonic waves are reflected from the top surface of the base, and the reflected ultrasonic waves enter the bottom surface of the transducer and acoustically firmly support the transducer on the bottom surface, which reduces the vibration of the bottom surface of the ultrasonic transducer. is alleviated.

(Effects of the Invention) As described in section L of the invention, according to the present invention, the vibration of the lower surface of the ultrasonic transducer is alleviated, so the ultrasonic waves radiated from the lower surface are reduced, and as a result, the basic The ultrasonic waves propagating to the table are reduced, and the conversion efficiency in electric-ultrasonic conversion and ultrasonic-electrical conversion is improved. As a result, if this ultrasonic transducer is used on the transmitting side, the output of the ultrasonic waves emitted from the top surface of the transducer can be increased, and if the same transducer is used on the receiving side, a large electrical output can be generated. Obtainable.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure shows a plurality of ultrasonic transducers 10°10... that convert electrical signals into ultrasonic waves or convert ultrasonic waves into electrical signals on a base 2.
The support structure is shown in a perspective view, which is arranged in a line in the front-back direction of the base 20 and supported by lead wires 11, 11, 12, 12, . . . on the base 20.

The base 20 is made of a hard material such as iron.
As shown in FIGS. 1 and 2, printed circuit boards 21 and 22 are fixed to the left and right sides of 0 with screws 23, respectively. The printed boards 21, 22 are made of an insulating material such as epoxy resin, and conductive patterns 21 corresponding to the ultrasonic transducers 10, 10, . . . are formed on the boards 21, 22, respectively.
a, 21a..., 22a, 22a... are formed. These conductive patterns 21a, 21a..., 2
One end of each of the lead wires 24, 24, . . . is electrically connected to 2a, 22a, . . . by soldering. Note that each end of the lead wires 24, 24, . . . is connected to an electric circuit (not shown).

The ultrasonic vibrator 10 includes a piezoelectric body 10a that vibrates in the vertical direction, and a pair of upper and lower electrodes 10 that are provided to sandwich the piezoelectric body 10a in the vertical direction and are formed into thin plate shapes made of a conductive metal material.
b, 10c. Upper electrode 10b
One end of the bent lead wire 12 is fixed to the mold by soldering, and the other end of the lead wire 12 is fixed to the conductive pattern 22a by soldering. One end of a lead wire 11 bent into a mold is fixed to the lower electrode 10c by soldering, and the other end of the lead wire 11 is fixed to the conductive pattern 21a by soldering. As a result, both electrodes 10b and joc of the ultrasonic transducer 10 are connected to conductive patterns 22a and 21, respectively.
electrically connected to a.

Further, these lead wires 11 and 12 are connected to the ultrasonic transducer 10.
The vibrator 10 is made of a material having sufficient rigidity to support its own weight, and the lower electrode 10c surface is separated from the top surface of the base 20 by a distance of It is mechanically supported by the base 20 so as to be parallel to the upper surface of the base 20.

In this case, assuming that the wavelength of the ultrasonic wave to be used in the air is input, the distance J is set to be approximately an integer multiple of a half wavelength (λ/2). In addition, the upper electrode of the ultrasonic vibrator 10! The Ob surface, the lower electrode 10c surface, and the upper surface of the base 20 are formed flat.

Next, as shown in FIG. 3, the effect of the embodiment configured as described above can be explained by applying the ultrasonic vibrator 10 to the transmitter A and causing the vibrator 10 to vibrate by the output of the oscillation circuit 31. When ultrasonic waves are emitted from the transducer 10 into the air, the ultrasonic transducer 10 is applied to the receiving device B, and the ultrasonic waves incident on the transducer 10 from the air are received by the receiving circuit 32. I will explain each case separately.

In the former case, the oscillation circuit 31 outputs to the ultrasonic transducer 10 an electric signal having a frequency substantially equal to the resonance frequency of the ultrasonic transducer 10, for example, about 200 km/R. This electric signal is transmitted through the lead wire 24 shown in FIGS. 1 and 2,
Conductive pattern 21a.

22a and lead wires 11.12 to the ultrasonic transducer 1.
It is attached between a pair of upper and lower electrodes 10c. By applying this electric signal, the ultrasonic vibrator 10 vibrates in the vertical direction at approximately 200 kilohertz, and the pair of upper and lower electrodes 10b
, 10c plane to emit ultrasonic waves of the above frequency in the vertical direction. At this time, most of the ultrasonic waves emitted from the lower electrode 10c surface and incident on the upper surface of the base 20 are reflected on the upper surface of the base 20 due to the difference in acoustic impedance between the air and the base 20. . Due to this reflection, the phase of the reflected ultrasonic wave is reversed with respect to the incident ultrasonic wave (the phase is π
deviated by a certain amount) and enters the surface of the electrode 10c again. In this case, since the distance J between the electrode 10c surface and the top surface of the base 20 is set to approximately an integral multiple of the half wavelength (λ/2) of the ultrasonic wave being used, the distance J between the electrode 10c surface and the top surface of the base 20 The round trip distance R2 from the top surface is approximately an integral multiple of the wavelength input of the ultrasonic wave, and the base 2
The ultrasonic waves reflected on the upper surface of the electrode 10c and incident on the electrode 10c surface and the ultrasonic waves radiated due to the vibration of the electrode 10c surface have opposite phases. (The phase is shifted by π.) In this way, the electric field Fi! on the lower side of the ultrasonic transducer 10! 10c
Since ultrasonic waves having a phase opposite to the vibrations on the electrode 10c surface are incident on the surface, the vibrations on the electrode 100 surface are canceled out, and the ultrasonic transducer 10 produces an acoustic wave on the electrode 10c surface. will be supported by

As a result, the amplitude of the lower electrode 100 surface of the ultrasonic transducer 10 becomes smaller, so the ultrasonic waves radiated from the electrode 10c surface are reduced, and the ultrasonic waves propagated to the base 20 are reduced. The conversion efficiency in electrical-ultrasonic conversion is improved. Also, when focusing on the upper electrode 10b surface of the ultrasonic transducer 10, the amplitude of the circumferential electrode tob surface is
It increases as the amplitude decreases in the 0c plane, so
The output of the ultrasonic waves radiated from the electrode 10b surface on the second side, that is, the output of the ultrasonic waves used increases.

In the latter case, the ultrasonic wave incident on the electrode Job surface on the opposite side of the ultrasonic transducer 10 shown in FIGS. 1 and 2 causes
The vibrator 10 vibrates in the vertical direction. This vibration causes
An electrical signal having the above frequency is induced between the pair of upper and lower electrodes 10b and 100, and this signal is transmitted to the lead wires 11 and 12.
, the conductive patterns 21a, 22a and the lead wire 24, and received by the receiving circuit 32 in FIG. In this way, when the ultrasonic transducer 10 is applied to the receiving device B, the vibration of the ultrasonic transducer 10 causes the lower electrode 10c to
Since ultrasonic waves are radiated from the surface toward the upper surface of the base 20, the vibrator 10 is acoustically supported by the lower electrode 10c surface, as in the case of the transmission B position A described above. As a result, in this case as well, the ultrasonic waves emitted from the lower electrode 10c surface of the ultrasonic transducer 10 are reduced, and the ultrasonic waves propagated to the base 2o are also reduced, so that the conversion in ultrasonic-electrical conversion is reduced. Efficiency is improved and the output of the electrical signal supplied from the ultrasound transducer 10 to the receiving circuit 32 is increased.

In order to confirm the above-mentioned effects, the present inventor conducted the following experiment, and the experimental results will be described here. As an experimental method, each ultrasonic transducer 10, 10(7) upper 1 of transmitter A and receiver B shown in FIG.
1 (7) Electrode Job, move the 10b surface a predetermined distance, for example, 50
The lower electrode 10 of the vibrator 10 is placed facing each other at a distance of about a centimeter, and the output of the oscillation circuit 31 is kept constant.
The distance J (see Figure 2) between the c-plane and the top surface of the base 2o is ``o''.
The output of the electrical signal received by the receiving circuit 32 was measured while gradually increasing from . Figure 4 shows the results of this measurement. According to this, when the wavelength of ultrasonic waves in the air is input, the electrical signal output is approximately equal to the distance l which is an integer multiple of 1/2 wavelength (input/2). It can be seen that it becomes larger when , and remains almost unchanged in other cases.

Note that the present invention can be implemented with the following modifications.

(1) In the above embodiment, the square lead wire 11°1
2; The ultrasonic transducer 1o is mechanically supported with respect to the base 2o by this, but as shown in FIG. 'Line I
I, 12 may be used to mechanically support the base 2o. The other configurations are the same as in the above embodiment.

(2) In the above embodiment, a case was explained in which the ultrasonic vibrator 10 that vibrates in the direction of the applied voltage (electric field direction) is used, but an ultrasonic vibrator that vibrates perpendicular to the direction of the applied voltage is used. It's okay. In this case, a pair of electrodes 10b
, 10c are provided on both the left and right sides of the piezoelectric body 10a, and the lower surface of the piezoelectric body 10a is made to face the base 20. Then, both electrodes] Ob
, 10C, the ultrasonic transducer 10 is mechanically supported on the base. The lead wires 11 and 12 may be linear as shown in FIG. 6, or rectangular as shown in FIG. 2. The other configurations are the same as in the above embodiment.

(:3) In the above embodiment, the upper surface of the base 2o is formed flat, but as shown in FIG.
A stepped groove 20 extending in the front-back direction of 0 (see Fig. 1)
a may be formed on the upper surface of the base 2o. Further, as shown in FIG. 8, a groove 20a having an arc shape or an elliptical arc shape
may be formed on the upper surface of the base 2o. The configuration of the pond is the same as in the above embodiment.

As described above, by providing the groove 20a on the upper surface of the base 20, the distance from the lower electrode 10c surface to the upper surface of the base 20 varies depending on the position of the electrode 10c surface. In this case, the travel distance of the ultrasonic waves from the upper surface of the base 20 to the lower surface of the electrode 10c also changes due to the change in the course of the ultrasonic waves due to reflection. As a result, the ultrasonic transducer 1
Although the maximum peak of the conversion efficiency of 0 is reduced compared to the maximum peak in FIG. 4, the slope of the peak in FIG. 4 becomes smoother. This means that, as mentioned in the experimental results above, the conversion efficiency of the ultrasonic transducer 10 is equal to the distance H by 172 wavelengths (λ/2).
This can be understood from the fact that it becomes larger when set to approximately an integer multiple of , and remains almost unchanged in other cases. Also, as mentioned above, since the slope of the mountain part has become smoother, the distance l
Even if set to a value different from λ/2°, 3・λ/2, etc., the ultrasonic transducer 10 will be able to apply a smaller force than in the above embodiment, but the lower electrode It will be acoustically supported by the 10c plane. As a result, according to this modification, mechanical support accuracy for the ultrasonic transducer 10 with respect to the base 20 is no longer required, and the production of the transmitter A or the receiver B becomes easier.

(4) In the modification of (3) above, the groove 20a is formed on the top surface of the base 20, but each ultrasonic transducer 1
Every 0.10... lower electrode 10C210c...
Even if stepped recesses or recesses having a cross section of a circular arc shape, an elliptical arc shape, etc. are formed on the upper surface of the base 20 at positions facing each surface, the same effect as the modification example (3) above can be obtained. Be expected.

Furthermore, a convex portion may be provided in place of the concave portion. When this convex portion is provided, a portion of the ultrasound emitted from the lower electrode 10c surface of the ultrasound transducer 10 and reflected from the upper surface of the base 20 is scattered, resulting in electrical-ultrasonic conversion. Although the conversion efficiency in ultrasound-to-electricity conversion may deteriorate to some extent, in this case as well, the ultrasound transducer 10 is acoustically supported by the lower electrode 10c surface, which is the same as the above case. It is.

Further, the surface of the lower electrode 10c of the ultrasonic transducer 10 may be formed into a stepped concave or convex shape, or may have a concave or convex cross section such as a circular arc shape or an elliptical arc shape.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a support structure for an ultrasonic transducer according to an embodiment of the present invention, FIG. 2 is a view of the structure shown in FIG. 1 viewed from the front of the base, and FIG. An example of an electric circuit when the ultrasonic transducer shown in the figure is applied to a transmitting device and a receiving device, FIG. 4 is a graph showing experimental results for confirming the effects of the present invention, and FIGS. 5 to 8 are FIG. 2 is a diagram showing a modification of the embodiment shown in FIG. 1; Explanation of symbols 10... Ultrasonic vibrator, 10a... Piezoelectric body, Job
, 10c..."electrode, 11.12---Lead wire, 20
...Base, 20a...Groove, 21°22...Printed board, 20a, 21a...Conductive pattern.

Claims (4)

[Claims] (1) An ultrasonic transducer supporting method in which an ultrasonic transducer that vibrates in a direction perpendicular to opposing upper and lower surfaces is supported on a base, the lower surface of the ultrasonic transducer being attached to the base. Mechanically supporting the ultrasonic transducer with respect to the base by a support member so as to face the upper surface and provide a gap between the lower surface of the ultrasonic transducer and the upper surface of the base; The ultrasonic transducer is acoustically supported on its lower surface by ultrasonic waves emitted from the lower surface of the ultrasonic transducer, reflected on the upper surface of the base, and incident on the lower surface of the base. A method for supporting an ultrasonic transducer, characterized by: (2) The ultrasonic wave according to claim 1, wherein the support member is constituted by a pair of lead wires that allow electrical connection between the ultrasonic transducer and the base side. How to support the vibrator. (3) The lower surface of the ultrasonic vibrator and the upper surface of the base are formed flat, and the distance of the gap between the lower surface of the ultrasonic vibrator and the upper surface of the base is adjusted to 2. The method of supporting an ultrasonic transducer according to claim 1, wherein the gap is set to approximately an integral multiple of half the wavelength of the gap. (4) Providing unevenness on the lower surface of the ultrasonic transducer or on the upper surface of the base opposite to the lower surface, and determining the distance from the lower surface of the ultrasonic transducer to the upper surface of the base on the lower surface of the ultrasonic transducer. 2. A method for supporting an ultrasonic transducer according to claim 1, wherein the support method is made to vary depending on the position of the ultrasonic transducer.