JPH0654859A - Ultrasonic transmitter - Google Patents

Abstract

PURPOSE:To provide the ultrasonic transmitter whose integrated output acoustic energy efficiency in a focus is high by preventing electric discharge between adjacent electrodes, and also, suppressing a decrease of a substantial driving area under a driving electrode, in the case a piezoelectric element is divided into plural elements and driven independently. CONSTITUTION:The ultrasonic transmitter is constituted so that a piezoelectric vibrator 4 group is constituted by dividing at least one electrode 2 into plural elements in a piezoelectric element 1 having electrode 2, 3 on both faces, and a strong ultrasonic wave is generated by applying a high voltage pulse from each independent driving power source 5 to each piezoelectric vibrators thereof 4. The electrode 2 is divided by forming at least a dividing groove 10 in the piezoelectric element 1 from the electrode surface along a dividing line, and also, embedding a high insulating material 11 whose insulation breakdown strength is higher than that of the piezoelectric element 1 in the dividing groove 10 so that a part there of swells from the electrode surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic wave transmitter for generating a strong ultrasonic wave by applying a high voltage to a piezoelectric element, such as a shock wave generator of a calculus breaking device.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a therapeutic device utilizing high-intensity ultrasonic waves, such as a calculus crushing device which irradiates a shock wave from outside the body to finely crush renal stones and gallstones and spontaneously discharge them for treatment. Piezoelectric elements are generally used in the transmitter of high-intensity ultrasonic waves used in such treatment devices.Piezoelectric elements whose resonance frequency exceeds 100 kHz have piezoelectric ceramic vibrations with electrodes on both sides. The child thickness longitudinal vibration mode is used. An ultrasonic wave transmitter including such a piezoelectric element emits an ultrasonic pulse by applying a high-voltage pulse to electrodes provided on both surfaces of the piezoelectric element.

By the way, in the above-described treatment apparatus, it is necessary to reduce the damage to normal tissue by concentrating the shock waves and ultrasonic waves applied to the affected area only on the affected area. Therefore, the ultrasonic wave transmitter is provided with a means for focusing ultrasonic waves, and generally, the ultrasonic wave emitting surface of the piezoelectric element is formed in a concave shape.

The shock wave is formed by an increase in pressure due to the focusing effect of the emitted ultrasonic waves and a non-linear phenomenon in the propagation process. In order to form a shock wave having a high sound pressure in the focal region, a piezoelectric material having a high electromechanical conversion efficiency is used, and a high voltage is applied to increase the amplitude of ultrasonic waves emitted from the piezoelectric element. It is important to increase the area of the beam to increase the energy density at the focal point. Here, the piezoelectric element becomes a capacitive load from the drive circuit, and when it becomes a piezoelectric element having a large area, the electric impedance of the piezoelectric element becomes too small in the drive circuit made of a semiconductor element having good drive controllability. Is divided into a large number and driven by a large number of drive circuits.

On the other hand, a focus position adjusting operation to the affected area,
There is a demand for electronically controlling the focus position in order to follow the movement of the affected part due to breathing or the like. As a method,
A plurality of piezoelectric elements are arranged in a concentric pattern, and an annular array in which the focal position in the ultrasonic wave emission direction is changed by the drive timing, or the piezoelectric elements are arranged in a matrix to set the focal position.
A two-dimensional array whose position is controlled in a three-dimensional space is considered.

As described above, the piezoelectric element used in an ultrasonic wave transmitter such as a calculus breaking device is often divided into a plurality of parts. As a method of dividing the piezoelectric element, it is common to divide the piezoelectric element by removing a part of the electrode provided on the surface opposite to the ultrasonic wave emitting surface. By the way, since a high voltage pulse of several kV is applied to the electrodes, in the above-described conventional division method, it is necessary to widen the division width of the electrodes so as not to discharge between adjacent electrodes. Here, if the number of divisions is small, there is no problem, but in the outer peripheral part of an annular array divided into equal areas or in a two-dimensional array, the spacing between the division lines becomes narrower, and if the division width (removal width) of the electrodes becomes wider, The ratio of the divided invalid area to the drive area under the drive electrode is relatively large, and the effective drive area relative to the total area of the piezoelectric element is reduced, resulting in a problem that the sound pressure is reduced at the focus. I will leave.

[0007]

As described above, in the ultrasonic wave transmitter having a plurality of divided piezoelectric elements, which is used for generating a shock wave in a calculus breaking device, it is necessary to obtain a strong ultrasonic wave. It is necessary to increase the drive pulse voltage, and along with this, to prevent discharge between adjacent electrodes,
The electrode spacing must be set wide. However, in the case where the interval for dividing the electrodes is narrow, widening the divided region substantially reduces the ratio of the drive region having the electrodes, which causes a problem that the sound pressure at the focus relatively decreases. .

The present invention has been made in order to solve such a problem, and in the case of dividing a piezoelectric element into a plurality of parts, the discharge between adjacent electrodes is prevented, and a substantial portion under the drive electrodes is provided. It is an object of the present invention to provide an ultrasonic wave transmitter capable of suppressing a decrease in a driving area.

[0009]

An ultrasonic wave transmitter according to the present invention constitutes a piezoelectric vibrator group by dividing at least one electrode of a piezoelectric element having electrodes on both sides into a plurality of piezoelectric vibrator groups. In an ultrasonic wave transmitter that applies a high voltage pulse from a driving power source to generate a strong ultrasonic wave, the electrodes are divided at least along the dividing line of the electrode from the surface of the electrode into the piezoelectric element. It is characterized in that the groove is formed and a high insulating material having a higher withstand voltage than the piezoelectric element is embedded in the divided groove so that a part thereof rises from the electrode surface.

[0010]

In the ultrasonic wave transmitter of the present invention, at least a dividing groove is formed in the piezoelectric element from the surface of the electrode along the dividing line of the electrode, and high insulation having a higher withstand voltage than the piezoelectric element is formed in the groove. The electrode is divided by embedding a conductive material so as to rise from the electrode surface. Here, the width of the dividing groove is narrowed within a range in which the high insulating material can sufficiently withstand the driving voltage applied, and the depth of the dividing groove is set to be equal to or larger than a distance at which the piezoelectric material causes dielectric breakdown by the driving voltage. If the depth is set so that the shortest path length on the groove surface is set, it becomes possible to sufficiently satisfy the withstand voltage between the electrodes while sufficiently reducing the interval (width of the groove) between adjacent electrodes. . This makes it possible to reduce the area of the divided portion that becomes an ineffective portion with respect to ultrasonic radiation, and to suppress the reduction of the electrode area that becomes the drive area. It is possible to realize a split drive type ultrasonic wave transmitter with good output efficiency.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the essential structure of an embodiment in which the present invention is applied to an annular array type ultrasonic wave transmitter which is an example of a split type ultrasonic wave transmitter. In the figure, reference numeral 1 is a piezoelectric element made of a piezoelectric ceramic material or the like. Although FIG. 1 shows the disk-shaped piezoelectric element 1 having a planar shape, a circular arc-shaped piezoelectric element having a concave surface, which has a converging effect by the element itself, is generally used. Here, it is represented by an easily illustrated flat plate element. On both main surfaces of the piezoelectric element 1,
Electrodes 2 and 3 are provided respectively. Of these electrodes, the upper electrode 2 is divided into rings (2a, 2b, 2c, 2d, 2e, 2f) so as to have the same area,
The lower electrode 3 is a common electrode. Then, as described above, the piezoelectric vibrator group (4, 4, ...) Is formed by dividing the upper electrode 2. Each of these piezoelectric vibrators 4, 4 ...
The focus position in the ultrasonic radiation direction can be changed by controlling the drive timing of each element 4.

A drive circuit 5 is provided on each of the electrodes 2 and 3.
Lead wires 6 and 7 are respectively connected to supply a drive voltage from the. Of these, signal leads 6, 6 ... Are connected to the respective divided upper electrodes 2a, 2b, 2c, 2d, 2e, 2f. Independent drive circuits 5, 5, ... Via these signal leads 6, 6 ,.
Drive voltage is applied to each piezoelectric vibrator 4 ,. When a high voltage pulse is applied from the drive circuit 5 to the piezoelectric vibrator 4, the piezoelectric element 1 vibrates at the resonance frequency in the thickness direction,
Emit an ultrasonic pulse into the propagation medium. Further, in order to form a focus at a predetermined distance, the drive time of each piezoelectric vibrator 4 is controlled so that the wavefront of the ultrasonic pulse emitted from each piezoelectric vibrator 4, 4 ... Is combined at the focus.

In the piezoelectric element 1, the lower electrode 3 side serves as an ultrasonic wave emitting surface, and an acoustic matching layer 8 is provided on the ultrasonic wave emitting surface side for acoustic matching with water as a propagation medium. There is. This acoustic matching layer 8 is also preferably formed of a highly insulating material having water resistance. The surface of the piezoelectric element 1 opposite to the ultrasonic wave emitting surface supports only the peripheral portion of the piezoelectric element 1 so that ultrasonic waves are not transmitted backward, and most of the surface is in contact with air. In addition, the lower electrode 3 on the ultrasonic wave emitting surface side
Touches the human body through the acoustic matching layer 8, water, and the film,
It is connected to the ground lead 7 for safety.

Here, referring to FIG. 10, an electrode division structure of a conventional annular array will be described. A high voltage pulse is applied to an ultrasonic wave transmitter used for calculus breaking or the like in order to generate strong ultrasonic waves. Therefore, it is necessary to increase the distance between the electrodes so that dielectric breakdown does not occur between the adjacent electrodes. For example, assume that a piezoelectric element with a diameter of 100 mm and a thickness of 4 mm is concentrically divided into 6 equal areas. FIG. 10A is a plan view showing a main part of the piezoelectric element based on the above assumption, and FIG. 10B is a sectional view thereof. Here, the radius of five dividing lines r each ^{_{formula: r n = (nr 0 2}} /6) 1/2 ( wherein, r ₀ is the number of the radius of the piezoelectric element, n represents the inside of the dividing lines , R ₁ = 20.4mm
, R ₂ = 28.9mm, r ₃ = 35.4mm, r ₄ = 40.8mm, r ₅ = 4
It will be 5.6 mm.

The piezoelectric element 1 is separated by removing the electrode 2 with a certain width around these dividing lines r, but the width of the electrode removing portion 9 is sufficiently large for the voltage applied to each piezoelectric vibrator 4. Insulation distance is required. The withstand voltage of the general piezoelectric element 1 is
It is about 5 kV / mm, but if it is limited to about 2 kV / mm with a margin, for example, a voltage of 8 kV can be applied at a thickness of 4 mm.

When a high voltage pulse is applied between the lower common electrode 3 and the upper divided electrode 2, the adjacent divided electrodes 2,
A potential difference also occurs between 2 ... The equivalent electric circuit of the electrode division portion is shown in FIG. 11. The electric equivalent circuit of the piezoelectric element 1 is represented by a capacitance, and in general, compared with the capacitance C ₁ in the thickness direction of the piezoelectric element 1, the divided electrodes 2, 2, ... Since the capacitance C ₂ between them is small,
The potential difference between the adjacent electrodes 2, 2 ... Has a value close to the applied voltage. Therefore, when driving at a voltage close to the withstand voltage of the piezoelectric element 1, the interval between the adjacent divided electrodes 2, 2, ...
The same width as the element thickness is required.

FIG. 10 schematically shows an electrode state in the case where the width of the electrode removing portion 9 is 4 mm as described above. The area will be quite small. If the applied voltage is lowered, the width of the electrode removing portion 9 can be narrowed, but it is necessary to apply a high voltage in order to generate strong ultrasonic waves such as calculus breaking. In such an electrode state, the substantial drive area of the piezoelectric element 1 is reduced, and as a result, the sound pressure at the focus is reduced.

On the other hand, in the ultrasonic transmitter of the embodiment shown in FIG. 1, the dividing groove 10 is formed along the element dividing line r.
And a high insulating material 11 having a higher withstand voltage than the piezoelectric element 1 is embedded in each of the dividing grooves 10 so as to rise from the surface of the electrode 2 to form the upper electrode (driving electrode) 2. It is divided.

As for the shape of the dividing groove 10, as shown in FIG. 2, first, the groove width w may be a width that can sufficiently withstand the driving voltage applied to the highly insulating material 11. When the dielectric breakdown voltage of 11 is akV / mm 2 and the applied voltage is xkV, it is preferable to set it to 2 × / a mm or more in consideration of the safety factor. Specifically, for example, a highly insulating material such as silicone rubber has a breakdown voltage of about 20 kV / mm, and therefore has the same size as the annular array shown in FIG. 10 (diameter = 100 mm, thickness = 4 mm), the width w (electrode interval) w of the groove 10 should be 1 mm even if the safety factor is taken into consideration.

Further, the depth d of the dividing groove 10 may be set so that the shortest path length of the groove surface is set to be equal to or longer than the distance at which the piezoelectric element material causes dielectric breakdown by the driving voltage, and the dielectric breakdown voltage of the piezoelectric material is set. Groove depth where the shortest path length on the groove surface is 2x / bmm or more, that is, (2x / b-2x / a), in consideration of the safety factor, when bkV / mm and applied voltage are xkV.
It is preferable that the depth is not less than / 2 mm. Assuming the same size as the annular array shown in FIG. 10, there is no problem if the path length on the groove surface is 4 mm or more of the element thickness.
Therefore, the depth d of the dividing groove 10 may be about 1.5 mm.

As the depth of the dividing groove 10 becomes deeper, the element on the outer peripheral side having a smaller width to thickness ratio is affected by resonance in the width direction, but the depth of the dividing groove 10 is smaller than that of the piezoelectric element 1. If it is about half the thickness, the effect is small. further,
When a material having high hardness (hardness) is used as the highly insulating material filling the dividing groove 10, the influence of width vibration can be reduced.
On the contrary, when acoustic independence between the adjacent piezoelectric vibrators 4 is required, a deep groove may be formed, or the dividing groove 10 may be extended to the lower surface side of the piezoelectric element 1 so that each piezoelectric element 4 is formed. It is also possible to completely separate the piezoelectric element portion of the vibrator 4. In such a case, it is effective to use a flexible rubber-like material as the highly insulating material.

Further, it is preferable that the highly insulating material 11 with which the divided grooves 10 are filled is formed so as to cover the end portions of the divided electrodes 2 and rise over the electrode surface. This is because if the high-insulating material 11 is filled up to the same surface as the electrode surface, a discharge path that passes through the surface of the high-insulating material 11 is formed due to dielectric breakdown of air, and dielectric breakdown occurs at this portion. This is because there is a possibility. Here, the dielectric breakdown voltage of air is about 3 kV / mm, but for safety, it is limited to about 1 kV / mm, and the shortest surface path length of the highly insulating material from the exposed electrode to the exposed electrode of the adjacent element. The rising height h of the high-insulating material 11 may be set so that is within the limit. The highly insulating material 11 is not limited to the above-mentioned silicone rubber, and various insulating materials can be used as long as the withstand voltage is higher than that of the piezoelectric element material. For example, an epoxy resin for adhesion can be used. .

As is apparent from a comparison between FIG. 1 and FIG. 10, the division width (specifically, the width w of the groove 10) is sufficiently large in the annular array type ultrasonic wave transmitter according to this embodiment. Since it can be made small, even in the region where the distance between the dividing lines on the outer peripheral side is small, the drive electrodes 2 (for example, 2a and 2
It is possible to set the area of b) sufficiently large.
Therefore, the problem of sound pressure drop in the focal region can be almost ignored, and a split drive type ultrasonic wave transmitter with good output efficiency can be realized.

The above-mentioned annular array type ultrasonic wave transmitter can also be constructed by combining a ring-shaped piezoelectric element or a piezoelectric element obtained by dividing them into several pieces.

In such a case, as shown in FIG. 3, for example, first, electrodes 13 and 14 are formed on both main surfaces of each ring-shaped piezoelectric element 12, 12 ... When the ring-shaped piezoelectric elements 12, 12 ... Having the electrodes 13 and 14 are bonded with the adhesive 11, the adhesive 11
As the constituent material of the above, one having the same characteristics as the highly insulating material filled in the groove in the above-mentioned embodiment is used,
The width of the adhesive layer 11 becomes the same as the groove described above, and the adhesive 11 is raised so as to rise from the surface of the electrode 13.
Adjust the amount of. The electrodes 14 are commonly short-circuited and connected to the ground lead 7, and the acoustic matching layer 8 is formed on the surface of the electrodes 14. In this case, the acoustic matching layer 8 and the adhesive layer 11 are
It is preferable to use the same highly insulating material.

As described above, by assembling the ring-shaped piezoelectric element 12 as an annular array, the division width (specifically, the width of the adhesive layer 11) can be made sufficiently small as in the above-described embodiment. Therefore, the areas of the electrodes 13 and 14 can be set sufficiently large. The same applies to the case where the ring-shaped piezoelectric element 12 is further divided in the radial direction.

In the annular array of the above embodiment, both electrodes 13 and 14 of the piezoelectric element 12 serve as divided electrodes. Further, the width of the adhesive layer 11 exhibits the same action as that of the dividing groove, and can be considered as a dividing groove which reaches from the one surface of the piezoelectric element 12 to the other surface.

When the ring-shaped piezoelectric elements are combined to form an annular array as in the above-described embodiment, the ring element having a narrow outer peripheral side has a small width-to-thickness ratio. Therefore, the resonance frequency in the width direction may have an adverse effect, but by using a material having high hardness (hard) as the adhesive layer 11, it is possible to suppress the resonance frequency in the width direction. For resonance in the width direction, an ultrasonic wave transmitter in which the piezoelectric element 1 is integrated and only one electrode 2 is divided, as in the embodiment shown in FIG. 1, is more advantageous.

Further, when the piezoelectric elements are divided due to the capacitance of the driving circuit, or the piezoelectric elements are arranged in a matrix.
Even in the case of a two-dimensional array (for example, one having a dividing line r as shown in FIG. 2), by making the structure similar to that of FIG. 1 or 3, the divided region is minimized and the reduction of radiant energy is suppressed. be able to.

Next, another embodiment of the present invention will be described.

FIG. 5 is a sectional view showing the structure of an ultrasonic wave transmitter for shock wave generation (see Japanese Patent Application No. 4-014086) to which the present invention is applied. In the ultrasonic wave transmitter shown in FIG. 5, a back surface element 15 made of a material having substantially the same acoustic impedance as the piezoelectric element 1 and having substantially the same thickness and area is bonded to the back surface of the piezoelectric element 1. The back element 15 is usually
The same material as that of the piezoelectric element 1 is used so that it is not driven by voltage application.

As described above, when the back element 15 is made of the same material as the piezoelectric element 1 and an insulating material, the electrode 16 provided on one surface of the back element 15 is turned to the other surface to form the electrode of the back element 15. A voltage pulse is applied to each divided electrode 2 of the piezoelectric element 1 from each independent driving circuit 5 via 16. In this structure, since the back surface element 15 has no potential difference, only the piezoelectric element 1 is driven. It is more preferable to use the back element 15 that is not subjected to the polarization treatment. The electrode 16 on the back surface element 15 side may be formed on the entire circumference of the surface, or may be formed only on a minute area connected to the drive electrode 2 of the piezoelectric element 1.

The back element 15 described above is divided similarly to the piezoelectric element 1. In FIG. 5, the piezoelectric element 1 and the back surface element 15 are each divided into two parts. Then, these are divided into the dividing grooves 10 and 17 in the piezoelectric element 1 and the back surface element 15, respectively, as in the above-described embodiment.
Is formed so that the divided portion is as small as possible. The division groove 10 on the piezoelectric element 1 side is formed so as to satisfy the same conditions as those of the above-described embodiment, but the back element 15 is formed.
The width of the divided groove 17 on the side is formed to be at least larger than the width of the divided groove 10 of the piezoelectric element 1, and the gap between the adjacent electrodes 16 causes a gap between the electrodes 2 of the piezoelectric element 1 due to misalignment during bonding. It is preferable not to be narrower than the interval. The high insulating material 11 filling the dividing grooves 10 and 17 is 2
An adhesive may be used to bond the two elements 1 and 15, or another highly insulating material may be filled after the bonding.

If the back element 15 is made of a conductive material such as metal, it is not necessary to form an electrode. With such a structure, it is possible to easily lead out from the electrode 2 of the piezoelectric element 1. FIG. 6 shows a case where the back surface element 15 is made of a conductive material, and the dividing groove 10 of the piezoelectric element 1 is shown.
It is sufficient to divide the back element 15 made of a conductive material into a width at least wider than the width, and fill the highly insulating material 11 between them.

As in each of the above-mentioned embodiments, the back surface element 15 having an acoustic impedance substantially equal to that of the piezoelectric element 1 is provided on the surface of the piezoelectric element 1 on the side opposite to the ultrasonic reflection surface, thereby preventing the element from being destroyed. It is possible to increase the shock wave sound pressure.

Next, a case of forming an annular array with the ultrasonic wave transmitter having the above-mentioned back surface element will be described with reference to FIG. The division of the piezoelectric element 1 is performed by forming the division groove 10 as in FIG. 1 and filling the division groove 10 with the highly insulating material 11. Further, the back surface element 15 made of an insulating material is formed with a dividing groove 17 having a width at least wider than that of the dividing groove 10 formed in the piezoelectric element 1 at a position corresponding to the groove position of the piezoelectric element 1, and also has a high insulating property. Fill with material 11.

Since the electrode 16 of the back surface element 15 is divided in a ring shape, it cannot be drawn out to the back surface in the wrap-around structure. Therefore, by forming a conductive path 18 from each electrode 16a of the back element 15 on the side in contact with the divided electrode 2 of the piezoelectric element 1 to the electrode 16b on the back surface of the back element 15, each ring-shaped piezoelectric vibrator 4 is formed. The electrode is pulled out from. FIG. 7B shows a case where the plane positions of the conductive paths 18 electrically connected to the divided electrodes 2 of the ring-shaped piezoelectric vibrators 4 are arranged so that the lead connection electrodes 16b from the drive circuit do not come into close contact with each other. Is shown.

The conductive path 18 penetrating the back surface element 15 is formed at a predetermined position by laser processing or a diamond drill when the back surface element 15 is formed of piezoelectric ceramics of the same material as the piezoelectric element 1. It can be formed by providing a through hole, injecting the same silver paste as in the formation of the surface electrode 16b into the through hole, and performing a heat treatment. A two-dimensional array arranged as shown in FIG. 4 can be formed with the same structure.

Further, FIG. 8 shows a structure in the case where an ultrasonic wave transmitter composed of laminated piezoelectric elements is divided. 2
The piezoelectric elements 1 are laminated so that the polarization directions are opposed to each other,
A conductive member 19 made of a thin metal plate or a plurality of metal wires is sandwiched and adhered to the joint surface for lead extraction. The two piezoelectric elements 1 are divided grooves 1 correspondingly formed.
It is divided into two regions by the highly insulating material 11 filled in 0 and 10. The electrodes 3 on the exposed surface side of each of the laminated piezoelectric elements 1 are commonly short-circuited and connected to the ground lead 7, and the conductive members 19 drawn out from the central portion of the connection are connected to the signal leads 5, respectively, as illustrated. A drive voltage is applied from each drive circuit omitting. The ultrasonic wave emitting surface and the surface on the opposite side have the same structure as the conventional one.

In comparison with the conventional piezoelectric element, the thus constructed piezoelectric element has substantially the same resonance frequency and wave number if the entire thickness is the same, and if the voltage applied between the two terminals is the same, the element is The applied electric field doubles and the radiated sound pressure can be increased.

It is difficult to form an annular array with the ultrasonic wave transmitter having the above-mentioned laminated structure, but as shown in FIG. 9, for example, the circular vibrator 20 can be divided into four. In FIG. 9, a dividing groove is formed along the dividing line r in the same manner as in the laminated ultrasonic wave transmitter shown in FIG.
For the lead connection, a part 19a is pulled out from the end of the piezoelectric element, and is sandwiched and bonded between the piezoelectric elements so as not to protrude into the dividing groove.

[0043]

As described above, according to the ultrasonic wave transmitter of the present invention, in the ultrasonic wave transmitter of the division drive type driven by the high voltage pulse, the ineffective portion is set against the ultrasonic wave radiation. It is possible to reduce the area of the divided portion and suppress the substantial reduction of the driving area. Therefore, it is possible to provide an ultrasonic wave transmitter having a good output efficiency, which suppresses a decrease in sound pressure in the focal region as much as possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a schematic configuration of an ultrasonic wave transmitter according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing an electrode division portion of the ultrasonic wave transmitter shown in FIG.

FIG. 3 is a cross-sectional view of essential parts showing a schematic configuration of a transducer-divided ultrasonic wave transmitter according to another embodiment of the present invention.

FIG. 4 is a diagram for explaining the concept of a two-dimensional array type ultrasonic wave transmitter.

FIG. 5 is a sectional view showing a schematic configuration of an ultrasonic wave transmitter having a back surface element according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view showing another configuration example of an ultrasonic wave transmitter having a back surface element.

FIG. 7 is a diagram showing a schematic configuration of an annular array type ultrasonic wave transmitter having a back surface element according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a schematic configuration of a laminated structure type ultrasonic wave transmitter according to an embodiment of the present invention.

FIG. 9 is a plan view showing another configuration example of a laminated structure type ultrasonic wave transmitter.

FIG. 10 is a diagram showing a schematic configuration of a conventional annular array.

FIG. 11 is a diagram showing an equivalent electric circuit of an electrode division unit in the ultrasonic wave transmitter.

[Explanation of symbols]

 1 ... Piezoelectric element 2 ... Divided electrode 3 ... Common electrode 4 ... Piezoelectric vibrator 5 ... Driving circuit 10 ... Divided groove 11 ... Highly insulating material

Claims (1)

[Claims] 1. A piezoelectric vibrator group is configured by dividing at least one electrode of a piezoelectric element having electrodes on both sides into a plurality of parts,
In an ultrasonic wave transmitter that applies a high voltage pulse from a driving power supply to each of these piezoelectric vibrators to generate a strong ultrasonic wave, the electrodes are divided from the electrode surface along the division line of the electrodes to the piezoelectric element. At least a dividing groove is formed in the element, and a high insulating material having a higher withstand voltage than the piezoelectric element is embedded in the dividing groove so that a part thereof rises from the electrode surface. And ultrasonic wave transmitter.