JPH05184572A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To enable the formation of the ultrasonic probe to <=3mm diameter and the maintenance thereof at good SN so as to widen a frequency band by using one main surface of a piezoelectric plate as a flat reference plane and the other main surface as a slope and leading out the exciting electrodes of a wave transmitting/ receiving surface by a conductive layer formed on the outside surface of a cylindrical case to a metallic cap. CONSTITUTION:The piezoelectric plate 1, the one main surface of which is used as the flat reference plane and the other surface as the slope and which is formed with the exciting electrodes 2a, 2b on both the main surfaces is so fixed to the one opening end of a holding case 11 as to close this end. A metallic cap 13 having a through-hole in its central part is then fixed to the other opening end of the case 11. The thin-film- like conductive layer 18 by vapor deposition of aluminum is thereafter formed on the wave transmitting/receiving surface of the piezoelectric plate 1 and the outer periphery of the case 11 and the metallic cap 13 to electrically conduct the exciting electrode 2b to the metallic cap 13 and a shielding net wire 16. A protective film 19 consisting of an insulating resin is formed by CVD on the outside surface of the conductive layer 18. This protective film 19 on the wave transmitting/receiving surface side is commonly used as a sound matching layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field of application of a small-sized ultrasonic probe which is inserted into a body cavity and diagnoses the inside of the body cavity. Regarding the structure of the child.

[0002]

BACKGROUND OF THE INVENTION An ultrasonic probe is useful as an ultrasonic wave transmitter / receiver in an ultrasonic diagnostic apparatus for medical use. Among them,
Small-sized ultrasonic probes for use in body cavities such as the esophagus, anus, urethra, and blood vessels are becoming indispensable for the advancement of high medical care. Then, for these things, there is a background that smaller size and higher performance are required in order to reduce the burden on the patient and improve the accuracy.

[0003]

2. Description of the Related Art FIG. 3 is a sectional view of an ultrasonic probe for explaining a conventional example of this type. The ultrasonic probe is, for example, a disk-shaped piezoelectric plate 1 made of lead zirconate titanate (PZT).
Is configured as an ultrasonic wave generation source. Excitation electrodes 2 (ab) are formed on both main surfaces of the piezoelectric plate 1, and folding electrodes 2c are provided from one main surface to the other main surface. Then, it is fixed to one opening end of the resin-made cylindrical holding case 3 by an adhesive (not shown) so as to close it. However,
The other main surface having the folding electrode 2c is the inner side, and the one main surface is the outer side as the ultrasonic wave transmitting / receiving surface. Holding case 3
From the other open end, a cylindrical metal cover 4 having one end opened is provided so as to cover the outer peripheral surface of the holding case 3.
The metal cover 4 penetrates through the central portion on the other end side, and the cable 7 coated with the lead wires 5 and 6 for the signal line and the reference potential is inserted therethrough. The signal lead wire 5 is directly connected to the excitation electrode 2b on the other main surface of the piezoelectric plate 1 by soldering or the like. Further, the reference potential lead wire 6 is connected to the metal case 4, and the folded electrode 2c is electrically led out by the relay lead wire 8 that penetrates the side wall of the holding case 3 insulatively. The metal cover 4 is covered with a protective case 9 made of resin having the same shape. Then, the acoustic matching layer 10 is provided on the transmission / reception surface side.
Reference numeral 11 in the drawing is a backing material formed by pouring resin after the piezoelectric plate is fixed. With such a structure, the diameter can be made about 5 to 6 mm, and it is mainly used mainly in the esophagus. Then, the shielding effect of the metal cover 4 covering the holding case 3 enhances the signal-to-noise ratio (SN ratio) and improves the characteristics.

[0004]

However, in the ultrasonic probe having the above structure, the diameter is 5 to 6 mm as described above.
Since it is so small, it cannot be inserted into, for example, a blood vessel having a diameter of about 3 mm or less. Therefore, it has been considered that the diameter of the piezoelectric plate 1 is made as small as possible, and the piezoelectric plate 1 has a similar structure for intravascular use. However, in such a thing, the metal cover-4
In addition, the thickness of the protective case 9 was limited, and it was not practical. Therefore, in reality, the metal cover 4 is omitted, and the holding case 3 is directly covered with a protective case for use in the blood vessel. However, in this case, the shield effect of the metal cover 4 disappears, the SN ratio is lowered, and the diagnostic ability is lacking. In any case, the presence of the folding electrode 2c makes the sound field characteristics asymmetric and reduces the effective transmitting / receiving area of ultrasonic waves. In particular, the smaller the piezoelectric plate 1 (for example, about 1 mm),
There is also a problem that the piezoelectric plate 1 cannot be made extremely small because the effect on the effective transmission / reception area may be great.
Since the lead electrode 8 is connected to the folded electrode 2c, for example, the folded electrode 2c needs an area equal to or larger than the diameter of the piezoelectric plate 1 regardless of its size. In addition, since the piezoelectric plate has a flat plate shape, the band width is narrow, and there is a problem that in-vivo information cannot be obtained in a wide frequency range. For this reason, for example, there is a piezoelectric plate having a curved surface (so-called convex). However, since such a piezoelectric plate has a small diameter, it is difficult to perform the polishing work and the mounting work to the holding case 3, and the characteristics vary. There was a point that it was difficult to adopt because it occurred and the sound axis was deviated.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic probe which can have a diameter of 3 mm or less, and in particular maintains a good SN ratio and has a wide band.

[0006]

According to the present invention, one main surface of a piezoelectric plate is a flat reference surface and the other main surface is an inclined surface, and the piezoelectric plate is provided at one opening end of a cylindrical case so as to close it. Provide a conductive lid on the other open end to close it,
The excitation electrode on any one of the main surfaces inside the tubular case of the piezoelectric plate is led out by a signal lead wire insulated through the conductive lid, and ultrasonic waves of the piezoelectric plate are generated. The excitation electrode on the other main surface that serves as the wave transmission / reception surface is led out by a conductive layer formed on the outer surface of the cylindrical case and electrically connected to the reference potential lead wire, and a protective film is formed on the conductive layer. In addition to the above, the protective film is also provided on the wave transmission / reception surface to serve also as the acoustic matching layer. An embodiment of the present invention will be described below.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an ultrasonic probe for explaining one embodiment of the present invention. The description of the same parts as in the previous embodiment will be simplified. The ultrasonic probe is fixed to the piezoelectric plate 1 for generating ultrasonic waves at one open end of the holding case 11 so as to close it. The piezoelectric plate 1 has one main surface of the piezoelectric plate as a flat reference surface and the back surface as an inclined surface, and the excitation electrodes 2 (ab) are formed on both main surfaces. In this embodiment, the piezoelectric plate 1
Holding case 11 with one main surface serving as the reference surface of
And is fixed so as to substantially coincide with the opening end face of the. Then, a large amount of thermosetting resin is used when the one open end is fixed to the step portion, and the surplus portion is made to flow into the holding case 11. That is, this thermosetting resin is used as the backing material 12 at the same time when the piezoelectric plate 1 is fixed. At the other open end of the holding case 11, a metal lid 13 having a through hole at its center is fixed. The coaxial cable 14 is inserted through the through hole, and the core wire of the coaxial cable 14 is fixed to the excitation electrode 2a on the other main surface of the piezoelectric plate 1 by solder or the like, using the lead wire 15 for the signal wire. Further, the shield net wire 16 is fixed inside the metal lid 13 by a conductive adhesive 17. Then, the excess space of the conductive adhesive 17 is used to replenish the internal voids. A thin film conductive layer 18 formed by vapor deposition of aluminum (Al) is formed on the wave transmitting / receiving surface of the piezoelectric plate 1 and the outer circumferences of the holding case 11 and the metal lid 13.
Is formed. That is, the excitation electrode 2b on the wave transmission / reception surface of the piezoelectric plate 1 is electrically connected to the metal lid 13 (and the shield mesh wire 16). Then, a protective film 19 made of an insulating resin is formed on the outer surface of the conductive layer 18, for example, by CVD (Chmical Vapor).
por deposition). The protective film 19 on the transmitting / receiving surface side is also used as the acoustic matching layer.

With such a structure, since the excitation electrode 2b on the wave transmitting / receiving surface is led out to the metal lid 13 by the conductive layer 18, it is not necessary to provide the folding electrode 2c of the conventional example on the piezoelectric plate 1, and accordingly, While maintaining the symmetry of the sound field characteristics,
The effective transmission / reception area of the piezoelectric plate 1 can be the actual area, and the size of the piezoelectric plate 1 itself can be reduced. Further, since the conductive film 18 and the protective film 19 are formed by vapor deposition without using the metal case 4 of the conventional example and the protective case 9 covering the same, the thickness can be reduced. Incidentally, the size of the piezoelectric plate 1 in this embodiment is 1.0 mm in diameter, and the total thickness of the holding case 11, the conductive film 18 and the protective film 19 is 0.2.
On the order of mm, the overall diameter is only 1.2 mm. In addition, since the conductive film 18 causes a shielding effect, it can be inserted into a blood vessel and can be miniaturized.
Make the ratio good. Since the piezoelectric plate 1 is not a plane parallel to the reference plane but is a plane parallel to the reference plane, the thickness is continuously changed, so that the bandwidth can be widened to obtain in-vivo information in a wide frequency range. Yes, and thus these can enhance diagnostic capabilities. Also,
Compared to the so-called convex curved surface of the conventional example, the back surface is simply an inclined surface, so that the polishing operation can be easily performed on the holding case, the characteristics can be made uniform, and the sound axis and the like can be easily aligned.

[0009]

[Other Matters] In the above embodiment, the coaxial cable 14
Although the excitation electrode 2 (ab) is derived by using, the cable is not limited to this as shown in FIG. 2 and may be a cable in which lead wires 20 and 21 for signal and reference potential are simply coated. .. Further, the conductive film 18 is also formed on the excitation electrode 2b on the wave transmission / reception surface side of the piezoelectric plate 1, but it suffices that conductivity be measured in the peripheral portion thereof, and the entire surface of the excitation electrode 2b is directly protected without vapor deposition. The film 19 may be formed. In addition, the holding case 11
Although the metal lid 13 is provided on the other opening end of the above, a resin 23 or the like having a metallized layer 22 on the surface may be used in place of the metal lid. Is. Further, although the signal lead wire 15 is directly fixed to the excitation electrode 2a, a metallized layer 22 may be provided on the inner wall of the holding case 11 and connected thereto. In this case, since solder or the like for fixing the signal lead wire 15 does not adhere to the piezoelectric plate 1, there is no risk of deterioration of vibration characteristics. Further, although the flat reference surface of the piezoelectric plate 1 is used as the wave transmission / reception surface side, it is also applicable that the inclined surface side is used as the wave transmission / reception surface side. However, it is practical to use the reference surface as the transmitting / receiving surface side because it is easy to match the opening end face of the holding case 11 and the sound axis can be made perpendicular to the opening end face. Further, in the present invention, the diameter does not necessarily have to be 3 mm or less, that is, it can be applied to other than blood vessels,
Various modifications are possible.

[0010]

According to the present invention, the surface of the piezoelectric plate is a flat reference surface and the back surface is an inclined surface. Provide a lid on the other open end to close it,
The excitation electrode on any one of the main surfaces inside the tubular case of the piezoelectric plate is led out by a signal lead wire insulated through the conductive lid, and ultrasonic waves of the piezoelectric plate are generated. The excitation electrode on the other main surface that serves as the wave transmission / reception surface is led out by a conductive layer formed on the outer surface of the cylindrical case and electrically connected to the reference potential lead wire, and a protective film is formed on the conductive layer. In addition to the above, the protective film is also provided on the wave transmitting / receiving surface to serve also as the acoustic matching layer, so that the diameter is 3 mm.
It is possible to provide the following, and in particular, it is possible to provide an ultrasonic probe having a wide band while maintaining a good SN ratio, and its contribution is very large.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic probe for explaining an embodiment of the present invention.

FIG. 2 is a sectional view of an ultrasonic probe for explaining another embodiment of the present invention.

FIG. 3 is a sectional view of an ultrasonic probe for explaining a conventional example.

[Explanation of reference numerals] 1 piezoelectric plate, 1a reference surface, 1b inclined surface, 2 excitation electrode, 11 holding case, 12 backing material, 13 metal lid, 14 coaxial cable, 17 conductive adhesive, 18
Conductive layer, 19 Protective film.

Claims (1)

[Claims] 1. A piezoelectric plate for ultrasonic wave generation, wherein one main surface of the piezoelectric plate is a flat reference surface and the other main surface is an inclined surface, and excitation electrodes are formed on both main surfaces of the piezoelectric plate. The piezoelectric plate is provided at the open end of the cylindrical case so as to close the one open end, and the conductive lid is provided at the other open end of the cylindrical case so as to close the other open end, The excitation electrode on one of the main surfaces inside the cylindrical case of the piezoelectric plate is led out by a signal lead wire that is insulated through the conductive lid, and ultrasonic wave transmission / reception of the piezoelectric plate is performed. The excitation electrode on the other main surface to be the wave front is led out by a conductive layer formed on the outer surface of the cylindrical case and electrically connected to the reference potential lead wire, and a protective film is provided on the conductive layer. At the same time, the protective film is also provided on the transmitting / receiving surface to serve also as the acoustic matching layer. An ultrasonic probe to be.