JP2003210464A - Ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect received ultrasonic wave with high sensitivity and high selectivity, to allow an acoustic focus to come into the optimum position of organism tissue and to prevent sound pressure at that point from becoming lower than the peak sound pressure in the short-range sound field. <P>SOLUTION: A pair of fundamental wave transmitting rectangular opening piezoelectric elements 21a, 21b and a receiving piezoelectric element 22 for higher harmonic detection arranged being held between the elements 21a, 21b, are arranged in a straight line, and ultrasonic waves 2 of fundamental waves transmitted from a pair of fundamental wave transmitting rectangular opening piezoelectric elements 21a, 21b are transmitted through an acoustic lens 23. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe used for harmonic imaging ultrasonic diagnosis.

[0002]

2. Description of the Related Art A forceps hole of an endoscope is inserted, an ultrasonic transducer mounting portion is projected at a distal end portion thereof and brought into contact with a living tissue such as a stomach wall, and deep information of the stomach wall, for example, a layered structure of a mucous membrane is displayed with high resolution. Ultrasound diagnostic technology that visualizes ultrasonic images is becoming more important.

On the other hand, a small-diameter probe having a center frequency of 30 MHz, which is composed of a strip-shaped piezoelectric element, has been commercialized.

In this small-diameter probe, a good resolution corresponding to the frequency is obtained by transmitting and receiving ultrasonic waves at the center frequency, but on the other hand, the detectable depth (depth of penetration) is lowered. It occurs, leading to the result of narrowing the diagnostic area, resulting in the deterioration of the quality of diagnosis. Therefore, there is a demand for an improvement that improves the resolution without lowering the depth of penetration.

On the other hand, recently, as a new diagnostic modality in the field of extracorporeal ultrasonic diagnostics, the harmonic imaging diagnostic method is in the spotlight.

The harmonic imaging diagnostic method is
(1) Tissue harmonic imaging in which when ultrasonic waves propagate in a living body, harmonics that are influenced by the nonlinearity of living tissue and are superimposed on the fundamental ultrasonic waves are separated by various methods, and are imaged using this signal. Method, and (2) injecting a contrast agent bubble into the body, receiving the harmonics generated when the bubble bursts by the irradiation of transmitted ultrasonic waves, and separating the harmonics superimposed on the fundamental wave ultrasonic waves by various methods. , Is classified into the contrast harmonic imaging method for imaging using this signal.

It has been found that all of these have a S / N as good as a conventional B-mode tomographic image cannot obtain, and a diagnostic image with good resolution can be obtained, which contributes to the improvement of diagnostic accuracy of medical diagnosis. . The characteristics of harmonics are not only the effect of improving the contrast resolution due to the improvement of S / N, but also the frequency increases by an integral multiple, that is, the resolution in the depth direction improves.
It has major features that the lateral resolution is improved due to the smaller beam width and that the attenuation of ultrasonic waves can be suppressed to a level as low as the fundamental wave.

The ultrasonic transducer used in the conventional external body harmonic imaging diagnostic apparatus is
The same piezoelectric element has been used for both fundamental wave transmission and harmonic wave reception. In this case, since the signal level of the harmonic signal is much smaller than that of the fundamental wave, it is necessary to efficiently remove the fundamental wave component related to the deterioration of the harmonic image. For that purpose, special techniques such as pulse inversion, phase inversion, and use of Gaussian pulse are used.

On the other hand, the applicant of the present invention has disclosed, for example, in Japanese Patent Laid-Open No.
No. 01-258879 proposes a transmission / reception separated ultrasonic transducer for harmonic imaging that does not require these special techniques.

This transmission / reception separated ultrasonic transducer for harmonic imaging is composed of a ring-shaped piezoelectric element dedicated to fundamental wave transmission and a disc-shaped piezoelectric element dedicated to reception arranged in an inner circular portion thereof. By selecting the optimum combination, the harmonic components can be extracted with high sensitivity and high selectivity.

As described above, the present applicant has proposed that harmonics can be detected with high sensitivity and high selectivity by using the transmission / reception separation type ultrasonic transducer proposed by the present applicant. Also confirmed this effect. By applying this transducer structure to the small-diameter probe described above, it can be presumed that ultrasonic transmission / reception with high sensitivity, high resolution, and low attenuation with respect to frequency can be performed.

[0012]

However, the small diameter probe has a limited outer diameter because it is inserted through the needle hole.
For example, in order to be able to insert the forceps hole having an outer diameter of 2.8 mmφ, the maximum length of the transducer in the rotation direction is that the outer diameter of the sheath is 2.4 mmφ, and the width of the piezoelectric element to be arranged therein needs to be suppressed to about 1.5 mm. In this case, a transducer structure in which a ring-type transmitting piezoelectric element and a disc-shaped receiving piezoelectric element are arranged in the inner circular portion thereof, which has been already proposed by the applicant (see FIG. 10 of JP 2001-258879 A).
If the size is reduced, the aperture area of the ultrasonic transducer for transmission, which has a great influence on the harmonic reception sensitivity, cannot be increased.

That is, the reception sensitivity of harmonics is proportional to the aperture of the transmitting ultrasonic oscillator and is not related to the aperture of the receiving ultrasonic oscillator. Therefore, the case where the maximum sensitivity is exhibited is the case where the opening of the reception ultrasonic transducer is a point and the opening of the transmission ultrasonic transducer is close to the entire surface. In this case, for example, in FIG.
In FIG. 1A, the rectangular piezoelectric element 101 having a = 1.5 mm (width) and b = 2.5 mm (length) is compared with FIG.
Disc piezoelectric element 102 having an opening area of 4 (b)
The diameter R is R = 2 × (1.5 × 2.5 ÷ 3.14) ^0.5
= 2.2 mm, and the radius of gyration about the central axis of rotation 103 is about 1.5 times. With this size, it becomes impossible to insert the forceps into the forceps hole of the endoscope. Therefore, the opening of the ultrasonic transducer must be a rectangular opening.

Further, in the transducer structure in which the ring-type transmitting piezoelectric element and the disc-shaped receiving piezoelectric element are arranged in the inner circular portion thereof, the acoustic focus is on the transducer surface because the aperture length cannot be made large as described above. In some cases, the acoustic focus cannot be located outside the balloon sheath due to the local proximity. In order to diagnose living tissue, the acoustic focus needs to be placed outside the balloon, and a structure that enables it is necessary. For this reason also, the opening of the ultrasonic transducer must be a rectangular opening.

On the other hand, the rectangular piezoelectric element 1 shown in FIG.
In 01, if the aperture area is increased as much as possible for the purpose of sensitivity improvement, or if the aperture size is increased to improve the focusing property of ultrasonic waves, or the acoustic focus is made farther than the outer diameter of the sheath, the long side of the rectangular aperture is increased. And the ratio A (= 2a2 / 2a1) of the short side becomes large.

It is known that as the ratio A increases, the final peak point of the central axis sound field, that is, the sound pressure at the acoustic focus, becomes smaller than the sound pressure at the peak point in the near-field sound field that greatly changes. (FIGS. 16-19).

This is because the brightness of the ultrasonic diagnostic image at the final peak point, that is, in the vicinity of the acoustic focus cannot be obtained, or is affected by multiple reflections due to the balloon wall existing in the near field region, and the B mode of high quality is obtained. It means that the image cannot be obtained. Therefore, it is necessary to make the final peak point of the central axis sound field, that is, the sound pressure at the acoustic focus larger than the peak sound pressure in the short-range sound field region as much as possible even though the opening is rectangular.

The present invention has been made in view of the above circumstances, and it is possible to detect a received ultrasonic wave with high sensitivity and high selectivity, and further, to make the acoustic focus come to the optimum position of the living tissue,
Moreover, it is an object of the present invention to provide an ultrasonic probe capable of preventing the sound pressure at that point from lowering than the peak sound pressure in the near field.

[0019]

An ultrasonic probe of the present invention is a slender ultrasonic probe to be inserted into a body cavity, and a transmitting piezoelectric element for transmitting a fundamental ultrasonic wave,
A receiving piezoelectric element for receiving a harmonic signal induced in the object by transmitting the fundamental ultrasonic wave, and a plurality of the transmitting compression elements on a pedestal elongated in the insertion axis direction. The composite transmission ultrasonic sound field according to the above is arranged so as to be in close contact with the central axis of the reception ultrasonic sound field of the reception piezoelectric element.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 13 relate to an embodiment of the present invention, and FIG. 1 is a configuration diagram showing the configuration of an ultrasonic probe,
2 is a diagram showing a flexible shaft that can be used in the ultrasonic probe of FIG. 1, FIG. 3 is a configuration diagram showing a configuration of the ultrasonic transducer of FIG. 1, and FIG. 4 shows a shape of the ultrasonic transducer of FIG. 5, FIG. 5 is a first characteristic diagram showing the sound field characteristic of the ultrasonic transducer of FIG. 3, FIG. 6 is a second characteristic diagram showing the sound field characteristic of the ultrasonic transducer of FIG. 3, and FIG. 3 is a diagram for explaining electrode connection of the ultrasonic transducer of FIG. 3, FIG. 8 is a diagram for explaining a modified example of electrode connection of the ultrasonic transducer of FIG. 3, and FIG. 9 is for explaining a manufacturing method of the ultrasonic transducer of FIG. FIG. 10 is a second diagram illustrating the method of manufacturing the ultrasonic transducer of FIG. 3, and FIG. 11 is a third diagram illustrating the method of manufacturing the ultrasonic transducer of FIG. 4 is a fourth diagram illustrating the method of manufacturing the ultrasonic transducer of FIG. 3, and FIG.
FIG. 6C is a fifth diagram illustrating the method of manufacturing the ultrasonic transducer of FIG.

As shown in FIG. 1, the ultrasonic probe 1 of the present embodiment is a probe that is inserted into a body cavity by being inserted into a forceps channel of an endoscope, for example, and transmits a transmission fundamental wave ultrasonic wave 2. A balloon 5 capable of adhering to a wall of a body cavity having an ultrasonic transducer 4 for receiving a received ultrasonic wave 3 including a harmonic wave
And a sheath 6 connected to the balloon 5,
In the inner space 7 of the sheath 6, a two-core coaxial cable 8 for transmitting and receiving a signal is provided which is connected to the ultrasonic oscillator 4 having the ultrasonic oscillator 4 at its tip.

The balloon 5 is filled with the acoustic coupler liquid 9, and the two-core coaxial cable 8 is provided with the ultrasonic transducer 4 via the rotation support member 10 composed of a ball bearing or the like.
The balloon 5 and the sheath 6 are connected to the rotation support member 10
Are connected in a watertight manner (that is, the acoustic coupler liquid 8 is filled and held only in the balloon 5). And 2
The ultrasonic transducer 4 is generated by rotating the core coaxial cable 8.
Is rotatable about the rotating shaft 11.

Instead of the two-core coaxial cable 8, as shown in FIG.
You may provide the flexible shaft 14 which winds and accommodates the core coaxial cables 13a and 13b in a spline shape.

The ultrasonic transducer 4 of the present embodiment has a structure for improving sensitivity as a transmission / reception separation type structure. Therefore, as shown in FIG. 3, a pair of fundamental wave transmitting rectangular aperture piezoelectric elements 21a and 21b and a receiving piezoelectric element 22 for the purpose of detecting harmonics arranged so as to be sandwiched between them are linearly arranged to form a pair. The fundamental wave ultrasonic wave 2 transmitted from the rectangular aperture piezoelectric elements 21 a and 21 b for fundamental wave transmission is transmitted through the acoustic lens 23.

A transmission piezoelectric element damping layer 25 is provided on the pair of fundamental wave transmission rectangular aperture piezoelectric elements 21a and 21b, and the reception piezoelectric element 2 is provided.
2 is provided with a damping layer 26 for the receiving piezoelectric element. There are electrodes on the back surface of the acoustic lens 23 and on the back surfaces of the fundamental wave transmitting rectangular aperture piezoelectric elements 21a and 21b and the receiving piezoelectric element 22, and the back side of the acoustic lens 23 is a GND side electrode.

Here, as shown in FIG. 4, one side of each of the rectangular aperture piezoelectric elements 21a and 21b for transmitting the fundamental wave and the receiving piezoelectric element 22 is arranged to have the same size, and the center line of the side is the rotation axis. To do. Furthermore, the central axis of the ultrasonic transmission sound field formed by the pair of fundamental wave transmission rectangular aperture piezoelectric elements 21a and 21b and the central axis of the ultrasonic reception sound field by the reception piezoelectric element 22 are configured to coincide with each other, An acoustic focus 24 is formed on the central axis.

The aspect ratio (b / a) of the main transmission surface composed of a pair of fundamental-wave transmission rectangular aperture piezoelectric elements 21a and 21b.
=) A so that the sound pressure,
By reducing the peak sound pressure at the focus position and near-field sound field, a good ultrasonic diagnostic image is obtained.

Thus, by using the harmonics,
Spatial resolution and contrast resolution are improved compared to the case of transmitting and receiving with the fundamental wave. An even greater advantage of using harmonics is the reduction of peak sound pressure in the near field. This results in a larger sound pressure at the acoustic focus, which substantially improves the depth of penetration of the ultrasonic waves.

FIG. 5 shows such a situation. Even when the ratio A of the long side to the short side of the principal surface becomes about 3, unlike the case of the fundamental wave (FIG. 6), the peak sound in the near field is generated. The pressure is never greater. Also, it can be seen that the acoustic focus also becomes distant and the depth of penetration improves.

On the other hand, however, the peak sound pressure at the acoustic focus is halved compared to the case where the ratio A of the long side to the short side of the circular aperture or the main surface is 1 (FIG. 5: A = 3). Therefore,
Rectangular aperture piezoelectric element 21 for each fundamental wave transmission
By setting the ratio A (= c / a) of the long side to the short side of the main surfaces of a and 21b to approximately 1 (see FIG. 4), in the present embodiment, the rectangular aperture piezoelectric element 21a for transmitting the fundamental wave, 21b, the synthesized peak sound pressure at the acoustic focus of the fundamental wave can be increased, the received ultrasonic waves can be detected with high sensitivity and high selectivity, and the acoustic focus can be located at the optimum position of the biological tissue. It is possible to prevent the sound pressure at the point lower than the peak sound pressure in the near field.

The fundamental-wave transmitting rectangular aperture piezoelectric elements 21a and 21b are, for example, lead zirconate titanate PZ.
The piezoelectric element is made of piezoelectric ceramics such as T or bismuth layered structure or a single crystal such as quartz, lithium niobate, or KNbO3 (potassium niobate). The receiving piezoelectric element 22 is, for example, a polymer piezoelectric element made of a polymer resin such as polyvinylidene fluoride or vinylidene cyanide,
Alternatively, it is a composite piezoelectric element in which columnar piezoelectric ceramics are distributed in epoxy resin or the like.

Further, the GND electrodes of the two fundamental wave transmitting rectangular aperture piezoelectric elements 21a and 21b and the three GND electrodes of the receiving piezoelectric element 22 must be at the same potential. As a means for making the three GND electrodes the same potential, as shown in FIG. 7, the electrode side of the resin film (not shown) on one side of which the electrode to which the shield wire 31 of the two-core coaxial cable 8 is connected is formed. The three GND electrodes are bonded to each other with an adhesive. This resin film may be concaved later and used as the acoustic lens 23, or only the resin film may be removed and left as the electrode film. A resin film may be used as the acoustic matching layer.

The input electrode 32 on the drive voltage input side of the receiving piezoelectric element 22 is connected to one signal line 33 of the two-core coaxial cable 8 by soldering, and drives the fundamental wave transmitting rectangular aperture piezoelectric element 21a, for example. The input electrode 34 on the voltage input side is connected to the other signal line 35 of the two-core coaxial cable 8 by soldering. Here, since the input electrodes 34 and 36 on the drive voltage input side of the fundamental wave transmitting rectangular aperture piezoelectric elements 21a and 21b need to have the same potential, the input electrodes 34 and 36 are soldered with the same potential setting wiring 37. Are connected.

The rectangular aperture piezoelectric elements 21a and 21b for transmitting the fundamental wave are the receiving piezoelectric elements 22.
Since they are isolated so as to sandwich them, if they are connected as described above in order to bring them to the same potential, if two wires are connected by a wire, two rectangular aperture piezoelectric elements for transmitting the fundamental wave 2
One of 1a and 21b has one wire connection point, but the other rectangular aperture piezoelectric elements for transmitting a fundamental wave are two, including the connection to the coaxial cable.

The connection point becomes a mass load against the piezoelectric vibration, and a difference occurs in the vibration amplitude of the two rectangular aperture piezoelectric elements for transmitting the fundamental wave, which adversely affects the symmetry of the ultrasonic sound field. In addition, if the connection is made by soldering, the mass load varies due to the fluctuation of the soldering points. When the piezoelectric element is used for low frequencies and has a large thickness or has a large area, even if a slight difference in the mass load occurs, the influence on the sound field is small. However, when the present invention is applied to a high-frequency, small-diameter probe, which is the object of the present invention, the thickness of the piezoelectric element becomes small and the size thereof becomes small. There is a need for means for reducing the influence of wire wiring as much as possible even when the piezoelectric element is thin and its size is small.

As a means for this, as shown in FIG. 8, wiring is performed by ultrasonic wire bonding, and a relay substrate 41 is provided at a separated position in the vicinity of the piezoelectric element, and electrodes formed on the relay substrate 41. The wiring from each piezoelectric element is relayed to the pad. That is, no solder is used for one piezoelectric element, and one wire connection point 42, 43, 44 is one thin and flat wire 45,
46 and 47, electrode pads 48, 49 of the relay substrate,
Relayed to 50. The shield wire 31 of the two-core coaxial cable 8 is also connected to the GND electrode pad 51 of the relay board.

Here, a method of manufacturing the ultrasonic transducer 4 of the present embodiment will be described.

As shown in FIG. 9, a plurality of grooves 62 are formed on the electrode forming surface side of the receiving piezoelectric plate 61 having a single-sided whole surface electrode, and the resin base plate 6 is finally processed into the acoustic lens 23.
The electrode forming surface of the receiving piezoelectric plate 61 is bonded to the electrode 3. The resin base plate 63 also serves as an acoustic matching layer that acoustically matches the piezoelectric element in the ultrasonic probe and the ultrasonic transmission medium.

Next, as shown in FIG. 10, a cutting surface is cut from the upper surface of the receiving piezoelectric plate 61 to form the receiving piezoelectric element 22 as shown in FIG. A partial electrode is formed on the surface using a mask.

Subsequently, as shown in FIG. 12, a transmitting piezoelectric plate 64 having a single-sided entire surface electrode formed with a plurality of grooves 65 on the electrode forming surface side, and the receiving piezoelectric element 22 is set in the central portion of the groove 65. The transmission base plate 63 to the transmission piezoelectric plate 6
The electrode forming surfaces of No. 4 are joined. Then, the cutting surface is cut from the upper surface of the transmitting piezoelectric plate 64 to form the fundamental wave transmitting rectangular aperture piezoelectric elements 21a, 21 as shown in FIG.
b forming a rectangular aperture piezoelectric element 21 for transmitting a fundamental wave
A partial electrode is formed on the surfaces of a and 21b using a mask. After that, by cutting with the cutting unit 70, the unprocessed structure 71 of the ultrasonic transducer 4 before being processed into the acoustic lens 23 is formed. By processing the acoustic lens 23 on the resin base plate 63 of the unprocessed structure 71, it is possible to easily and inexpensively manufacture the plurality of ultrasonic transducers 4.

[Additional remarks] (Additional remark 1) The pedestal also functions as an acoustic lens configured to focus the two transmitting piezoelectric elements at desired positions.
The ultrasonic probe according to any one of 1.

(Additional Item 2) The pedestal also serves as an acoustic matching layer for acoustically matching the piezoelectric element in the ultrasonic probe and the ultrasonic transmission medium. The ultrasonic probe according to 1.

(Additional Item 3) The ultrasonic probe according to any one of claims 1 to 4, wherein a relay plate for relaying wiring is connected to the pedestal.

(Additional Item 4) The ultrasonic probe according to Additional Item 3, wherein a wiring for transmitting and receiving a signal to and from each piezoelectric element is singlely connected to one piezoelectric element.

(Additional Item 5) The ultrasonic probe according to Additional Item 3 or 4, wherein the wiring and the connection are formed by wire bonding.

(Additional Item 6) The common electrode for making all the potentials of the ultrasonic wave transmitting side electrodes of the respective piezoelectric elements to the ground potential is formed on the pedestal. Item 6. The ultrasonic probe according to any one of items 1 to 5.

(Additional Item 7) The relay plate is a substrate having electrodes formed on both surfaces, one electrode being connected to a common electrode, and the other surface having a pair of electrode pads formed thereon. The ultrasonic probe according to any one of Supplementary Notes 3 to 6.

(Additional Item 8) The transmission piezoelectric element has a ratio of two sides of 1 or more and 2 or less, according to any one of the additional items 1 to 7. Ultrasonic probe.

(Additional Item 9) A method of connecting and arranging a piezoelectric element on the pedestal is such that an electrode is formed on one surface of the pedestal, and the surface is left to have a dimension that finally becomes the length of the short side of the receiving piezoelectric element, The first step of manufacturing a receiving piezoelectric element material plate in which a plurality of grooves having a depth corresponding to the final thickness of the receiving piezoelectric element is formed, and an electrode is formed on one surface thereof, and the surface is finally formed. Manufacturing a transmission piezoelectric element material plate in which a plurality of grooves having a depth that exceeds the depth that is the thickness of the final transmission piezoelectric element is left while leaving a dimension that is the length of the short side of the transmission piezoelectric element. 2, the third step of joining the receiving piezoelectric element material plate prepared in the first step so that the electrode side faces face the electrodes formed on the pedestal, and the joined receiving piezoelectric element Of material board The fourth step is to grind the surface on which no electrode is formed to the final thickness of the receiving piezoelectric element, and to the surface of the receiving piezoelectric element on which no electrode is formed, which is obtained by grinding as described above. The fifth step of forming electrodes so that the side surfaces thereof are not coated, and the piezoelectric element material plate for transmission prepared in the second step faces the electrodes formed on the pedestal side surfaces thereof A sixth step of arranging and joining the reception piezoelectric elements formed in the steps up to the fifth step so as to straddle them, and grinding the surface of the joined transmission piezoelectric element material plate on which no electrode is formed. The seventh step of processing the final thickness of the transmitting piezoelectric element, and the electrode-unformed surface of the transmitting piezoelectric element obtained by grinding as in the seventh step, so that the side surface is not coated On the electrode Forming Eighth
The method of manufacturing an ultrasonic probe, comprising:

[0051]

As described above, according to the present invention, the received ultrasonic waves can be detected with high sensitivity and high selectivity, and the acoustic focus can be located at the optimum position of the living tissue. It is possible to prevent the sound pressure from being lowered below the peak sound pressure in the near field.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an ultrasonic probe according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flexible shaft that can be used in the ultrasonic probe of FIG.

FIG. 3 is a configuration diagram showing a configuration of the ultrasonic transducer of FIG.

FIG. 4 is a diagram showing the shape of the ultrasonic transducer of FIG.

5 is a first characteristic diagram showing a sound field characteristic of the ultrasonic transducer of FIG.

6 is a second characteristic diagram showing the sound field characteristic of the ultrasonic transducer of FIG.

FIG. 7 is a diagram for explaining electrode connection of the ultrasonic transducer of FIG.

FIG. 8 is a diagram illustrating a modification of electrode connection of the ultrasonic transducer of FIG.

FIG. 9 is a first diagram illustrating a method of manufacturing the ultrasonic transducer of FIG.
Illustration

FIG. 10 is a second diagram illustrating a method of manufacturing the ultrasonic transducer of FIG.

FIG. 11 is a third diagram illustrating the method of manufacturing the ultrasonic transducer of FIG.

FIG. 12 is a fourth diagram illustrating the method of manufacturing the ultrasonic transducer of FIG.

FIG. 13 is a fifth diagram illustrating the method of manufacturing the ultrasonic transducer of FIG.

FIG. 14 is a diagram illustrating an opening area of a transmission ultrasonic transducer of a transmission / reception separated ultrasonic transducer.

FIG. 15 is a diagram showing the shape of a rectangular piezoelectric element.

16 is a first characteristic diagram showing a sound field characteristic of the rectangular piezoelectric element of FIG.

FIG. 17 is a second characteristic diagram showing the sound field characteristic of the rectangular piezoelectric element of FIG.

FIG. 18 is a third characteristic diagram showing the sound field characteristic of the rectangular piezoelectric element of FIG.

FIG. 19 is a fourth characteristic diagram showing the sound field characteristic of the rectangular piezoelectric element of FIG.

[Explanation of symbols]

1 ... Ultrasonic probe 2 ... Transmission fundamental wave ultrasonic wave 3 ... Received ultrasonic wave 4 ... Ultrasonic transducer 5 ... Balloon 6 ... Sheath 7. Space inside the sheath 8 ... 2-core coaxial cable 9 ... Acoustic coupler liquid 10 ... Rotation support member 11 ... Rotation axis 12 ... Hollow contact coil 13a, 13b ... 1-core coaxial cable 14 ... Flexible shaft 21a, 21b ... Rectangular aperture piezoelectric element for fundamental wave transmission 22 ... Receiving piezoelectric element 23 ... Acoustic lens 24 ... Acoustic focus 25 ... Damping layer for transmitting piezoelectric element 26 ... Damping layer for receiving piezoelectric element

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[Procedure amendment]

[Submission date] April 16, 2002 (2002.4.1)
6)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

An ultrasonic probe of the present invention is a slender ultrasonic probe to be inserted into a body cavity, and a transmitting piezoelectric element for transmitting a fundamental ultrasonic wave,
A receiving piezoelectric element for receiving a harmonic signal induced in the object by transmitting the fundamental ultrasonic wave, and a plurality of front parts on a pedestal elongated in the insertion axis direction.
Constructed by arranging the central axis of the combined transmission ultrasonic field by serial transmission piezoelectric element for the substantially brought close contact so as to coincide with the central axis of the receiving ultrasonic field having piezoelectric elements for the reception.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Yokoi             2-43 Hatagaya, Shibuya-ku, Tokyo Ori             Inside Npus Optical Industry Co., Ltd. (72) Inventor Kazunari Tokuda             2-43 Hatagaya, Shibuya-ku, Tokyo Ori             Inside Npus Optical Industry Co., Ltd. F-term (reference) 4C301 AA03 BB28 BB30 EE06 EE07                       EE20 FF01 FF04 FF15 GA01                       GA15 GB04 GB14 GB18 GB19                       GB20 GB29 GB33 GC01 HH47                       HH48 JA17                 4C601 BB05 BB09 BB11 BB12 BB14                       EE03 EE04 EE30 FE01 GA01                       GA11 GA14 GB01 GB03 GB04                       GB14 GB19 GB20 GB32 GB35                       GB41 GC01 GC13 GC17 GD11                       GD12 HH26 HH35                 5D019 AA01 BB12 FF04 HH03                 5D107 AA20 BB07 CC01 CC10 CC12                       CC13 FF01 FF07

Claims (4)

[Claims] 1. An elongated ultrasonic probe to be inserted into a body cavity, wherein a transmission piezoelectric element for transmitting a fundamental ultrasonic wave and a harmonic signal induced in an object by the transmission of the fundamental ultrasonic wave are provided. A receiving piezoelectric element for receiving, and a receiving piezoelectric element having a central axis of a synthetic transmitting ultrasonic sound field formed by a plurality of transmitting compression elements on a pedestal elongated in the insertion axis direction. An ultrasonic probe characterized in that the ultrasonic probe is arranged in close contact with the central axis of the ultrasonic sound field. 2. The closely arranged state is such that the transmitting piezoelectric element, the receiving piezoelectric element, and the transmitting piezoelectric element are arranged in this order from the front end direction toward the proximal direction. Item 2. The ultrasonic probe according to item 1. 3. A damping layer for reception having a damping characteristic suitable for the piezoelectric element for reception is closely fixed to the piezoelectric element for reception on the surface opposite to the base, and damping suitable for the two piezoelectric elements for transmission. The ultrasonic probe according to claim 1 or 2, further comprising a reception damping layer having characteristics, which is closely fixed to the transmission piezoelectric element. 4. The receiving damping layer enters the pedestal side of the transmitting damping layer, and the transmitting damping layer fills a gap between the transmitting piezoelectric element and the receiving piezoelectric element to form an integrated structure. The ultrasonic probe according to claim 3, wherein the ultrasonic probe is configured.