JP2015029755A - Ultrasonic probe and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe which has an excellent performance for transmission and reception of an ultrasonic wave while forming a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements so as to be laminated with each other, and provide a method of manufacturing the same.SOLUTION: A plurality of inorganic piezoelectric elements 2 are formed so as to be arrayed with a pitch P on a surface 1a of a backing material 1, a first acoustic matching layer 3 and a second acoustic matching layer 4 are sequentially arranged on a plurality of inorganic piezoelectric elements 2, the second acoustic matching layer 4 includes a plurality of organic piezoelectric elements 5 formed so as to be arrayed with the same pitch P as the plurality of inorganic piezoelectric elements 2, and each of the organic piezoelectric elements 5 includes a first piezoelectric element part 5a and a second piezoelectric element part 5b laminated with each other in a sound axis direction.

Description

  The present invention relates to an ultrasonic probe and a method for manufacturing the same, and more particularly to an ultrasonic probe in which a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements are laminated together and a method for manufacturing the same.

  Conventionally, in the medical field, an ultrasonic diagnostic apparatus using an ultrasonic image has been put into practical use. In general, this type of ultrasonic diagnostic apparatus transmits an ultrasonic beam from an ultrasonic probe into a subject, receives an ultrasonic echo from the subject with the ultrasonic probe, and receives the received ultrasonic echo. An ultrasonic image is generated by electrically processing the signal.

In recent years, in order to perform more accurate diagnosis, harmonic imaging that receives and visualizes harmonic components generated by distortion of an ultrasonic waveform due to nonlinearity of a subject has become mainstream. In recent years, as a new diagnostic method using ultrasonic waves, photoacoustic imaging, which irradiates a living body with laser light and receives and visualizes weak and wide-band elastic waves generated by adiabatic expansion, has been in the spotlight. is there.
As an ultrasonic probe suitable for this harmonic imaging or photoacoustic imaging, for example, as disclosed in Patent Document 1, an inorganic piezoelectric material such as lead zirconate titanate (Pb (Zr, Ti) O ₃ ) is used. A plurality of laminated inorganic piezoelectric elements using a plurality of organic piezoelectric elements using an organic piezoelectric material such as polyvinylidene fluoride (PVDF) has been proposed.
A high-power ultrasonic beam can be transmitted by the inorganic piezoelectric element, and a harmonic signal can be received with high sensitivity by the organic piezoelectric element. In addition, a normal ultrasonic reception signal can be acquired by the inorganic piezoelectric element, and a wide-band signal of photoacoustic imaging can be received with high sensitivity by the organic piezoelectric element.

International Publication No. 2008/010509

Here, since the ultrasonic beams output from the plurality of inorganic piezoelectric elements are transmitted through the organic piezoelectric body and then transmitted from the ultrasonic probe into the subject, the thickness of the organic piezoelectric body is determined by the ultrasonic wave. Designed to increase the acoustic transmission of the beam. Specifically, the organic piezoelectric body is designed in the vicinity of a thickness that satisfies the λ / 4 resonance condition with respect to the wavelength λ of the fundamental wave transmitted from the plurality of inorganic piezoelectric elements, for example. For this reason, the organic piezoelectric material cannot be designed freely, and has to be designed with a certain thickness in order to satisfy the above resonance condition.
On the other hand, since the organic piezoelectric material has a relatively small relative dielectric constant, increasing the thickness of the organic piezoelectric material decreases the electric capacity, and the received signal generated by the ultrasonic wave received by the organic piezoelectric element is It was difficult to obtain efficiently. In addition, when the electric capacity is small, the thermal noise increases, so that the S / N ratio with the acquired signal tends to decrease.

  Further, when an organic piezoelectric element is laminated on an inorganic piezoelectric element, if the electrode positions of both elements do not coincide with each other with respect to the sound axis direction, there is a risk of defocusing and a decrease in reception efficiency. Therefore, it is desirable to align the electrode positions of the inorganic piezoelectric element and the organic piezoelectric element that are stacked on each other in the direction of the sound axis. However, in the conventional ultrasonic probe configuration and manufacturing method, both electrode positions are accurately set. It was difficult to match.

Furthermore, since the degree of crystallinity of an organic piezoelectric body gradually decreases as the temperature rises, the upper limit temperature for use is at a temperature considerably lower than the Curie point. For example, in a typical polyvinylidene fluoride (PVDF), the use upper limit temperature is 80 ° C., and in a polyvinylidene fluoride trifluoride ethylene copolymer (P (VDF-TrFE)), it is 100 ° C. Therefore, if exposed to a temperature higher than the upper limit temperature during use during the process, the ferroelectricity may deteriorate and depolarization may occur.
The dielectric deterioration can be circulated by repolarization, but the coercive electric field of the organic piezoelectric material is extremely large, about 400 kV / cm to 450 kV / cm. Therefore, in order to repolarize the organic piezoelectric material once depolarized on the device, it is necessary to apply an extremely high voltage, which is actually difficult in the process. From the above, when an organic piezoelectric element is laminated on an inorganic piezoelectric element, it is desirable to produce an ultrasonic probe with a low temperature process and a small number of thermal histories, but the configuration of a conventional ultrasonic probe In addition, it was difficult with the manufacturing method.

  The present invention has been made to solve such conventional problems, and has excellent performance for ultrasonic wave transmission / reception while forming a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements on top of each other. It is an object of the present invention to provide an ultrasonic probe having the above and a method for manufacturing the same.

  An ultrasonic probe according to the present invention includes a backing material, a plurality of inorganic piezoelectric elements arrayed on the surface of the backing material, and a first acoustic matching layer disposed on the plurality of inorganic piezoelectric elements. And a second acoustic matching layer disposed on the first acoustic matching layer, wherein the second acoustic matching layer is a plurality of organic piezoelectric elements arranged in parallel to the plurality of inorganic piezoelectric elements. Each of the organic piezoelectric elements has a plurality of piezoelectric element portions stacked on each other in the sound axis direction.

  The plurality of organic piezoelectric elements includes a sheet-like first and second organic piezoelectric layers stacked on each other with the ground electrode layer interposed therebetween, and a surface of the first organic piezoelectric layer opposite to the ground electrode layer. And a plurality of second signal electrodes arranged in a separated manner on the surface of the second organic piezoelectric layer opposite to the ground electrode layer. A plurality of first piezoelectric element portions are formed by the first organic piezoelectric layer, the ground electrode layer, and the plurality of first signal electrode layers, and the second organic piezoelectric layer, A plurality of second piezoelectric element portions can be formed by the ground electrode layer and the plurality of second signal electrode layers.

The second acoustic matching layer is formed on the surface of the plurality of first signal electrode layers opposite to the first organic piezoelectric layer and is disposed on the first acoustic matching layer. It is preferable to include a plurality of first resin layers and a sheet-like second resin layer formed on the surface of the plurality of second signal electrode layers opposite to the second organic piezoelectric layer. .
Here, the acoustic impedance of the first resin layer has a value greater than or equal to the acoustic impedance of the first and second organic piezoelectric layers, and the acoustic impedance of the second resin layer is the first and second organic layers. The piezoelectric layer preferably has a value equal to or lower than the acoustic impedance of the piezoelectric layer, and the first resin layer and the second resin layer are ± 10 with respect to the acoustic impedance of the first and second organic piezoelectric layers, respectively. Preferably having an acoustic impedance in the range of%.
The first and second organic piezoelectric layers can be formed from a vinylidene fluoride-based material.

The plurality of inorganic piezoelectric elements and the plurality of organic piezoelectric elements are preferably formed at the same position with respect to the sound axis direction at the same arrangement pitch.
Each inorganic piezoelectric element preferably has an inorganic piezoelectric layer, a signal electrode layer disposed on the surface of the inorganic piezoelectric layer, and a ground electrode layer disposed on the back surface of the inorganic piezoelectric layer.
Each inorganic piezoelectric element may be divided into a plurality of sub-dies along the arrangement direction of the plurality of inorganic piezoelectric elements.
The plurality of inorganic piezoelectric layers can be formed from a Pb-based perovskite structure oxide.

An acoustic lens may be further provided on the surface of the second acoustic matching layer opposite to the first acoustic matching layer.
Moreover, it is preferable to further include a plurality of organic piezoelectric element amplifiers directly connected to the plurality of organic piezoelectric elements.
In addition, the light irradiation unit further irradiates the subject with irradiation light, and the ultrasonic wave induced from the subject by irradiation of the irradiation light from the light irradiation unit is applied to a plurality of organic piezoelectric elements or a plurality of inorganic substances. It can also be received by a piezoelectric element.

  In the method of manufacturing an ultrasonic probe according to the present invention, a sheet-like inorganic piezoelectric layer is bonded to the surface of the backing material via the first conductive layer, and the second piezoelectric material is formed on the surface of the inorganic piezoelectric layer. A sheet-like acoustic matching layer is joined via a conductive layer, a sheet-like first resin layer is joined on the surface of the acoustic matching layer, and a third conductive layer is formed on the entire surface of the first resin layer. Then, by dicing from the third conductive layer to the inorganic piezoelectric layer at a predetermined pitch in the stacking direction, a plurality of inorganic piezoelectric elements are arranged and the third conductive layer is arranged at the same pitch as the plurality of inorganic piezoelectric elements. And the divided grooves are filled with resin, and then the first organic piezoelectric layer of the sheet-like first and second organic piezoelectric layers laminated together with the fourth conductive layer interposed therebetween is formed. A sheet-like second tree bonded on the surface of the third conductive layer and bonded to the acoustic lens The fifth conductive layer formed on the surface opposite to the acoustic lens of the layer is diced at the predetermined pitch to divide the fifth conductive layer at the same pitch as the plurality of inorganic piezoelectric elements, The fifth conductive layer formed on the surface of the second resin layer is aligned with the positions of the third conductive layer and the fifth conductive layer in the arrangement direction of the plurality of inorganic piezoelectric elements. By joining on the surface of the organic piezoelectric layer, a first piezoelectric element portion comprising a third conductive layer, a first organic piezoelectric layer and a fourth conductive layer, and a fifth conductive layer, respectively. This is a method of forming a plurality of organic piezoelectric elements in which a second organic piezoelectric layer composed of a second organic piezoelectric layer and a fourth conductive layer are stacked and arranged at the same pitch as a plurality of inorganic piezoelectric elements. .

  The alignment of the third conductive layer and the fifth conductive layer can be performed at both ends in the arrangement direction of the plurality of inorganic piezoelectric elements.

  According to this invention, the first acoustic matching layer is disposed on the plurality of inorganic piezoelectric elements, and the second acoustic matching layer disposed on the first acoustic matching layer is formed on the plurality of inorganic piezoelectric elements. A plurality of organic piezoelectric elements arranged in parallel to each other, and each organic piezoelectric element has a plurality of piezoelectric element portions stacked on each other in the sound axis direction, so that a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements are arranged. An ultrasonic probe having excellent performance with respect to transmission and reception of ultrasonic waves can be realized while elements are stacked on each other.

It is a fragmentary perspective view which shows the ultrasonic probe which concerns on Embodiment 1 of this invention. 1 is a cross-sectional view illustrating a configuration of an ultrasound probe according to Embodiment 1. FIG. 5 is a cross-sectional view showing the method of manufacturing the ultrasonic probe according to the first embodiment in the order of steps. FIG. 5 is a cross-sectional view showing a configuration of an ultrasonic probe according to Embodiment 2. FIG. 5 is a diagram illustrating a configuration of an ultrasound probe according to Embodiment 3. FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
1 and 2 show the configuration of an ultrasonic probe according to Embodiment 1 of the present invention.
The backing material 1 has a surface 1a extending along an XY plane perpendicular to the Z direction with the sound axis direction of the ultrasonic probe as the Z direction, and a plurality of inorganic piezoelectric elements on the surface 1a of the backing material 1 The elements 2 are arranged in the X direction at a predetermined pitch P. The plurality of inorganic piezoelectric elements 2 have a plurality of inorganic piezoelectric bodies 21 separated from each other, a signal electrode layer 22 is bonded to one surface of each inorganic piezoelectric body 21, and a ground electrode layer 23 is bonded to the other surface. It is joined. That is, each inorganic piezoelectric element 2 is formed of a dedicated inorganic piezoelectric body 21, signal electrode layer 22, and ground electrode layer 23 stacked in the Z direction.
A plurality of first acoustic matching layers 3 are bonded onto the plurality of inorganic piezoelectric elements 2. The plurality of first acoustic matching layers 3 are arranged in the X direction at the same pitch P as the plurality of inorganic piezoelectric elements 2, and are respectively disposed immediately above the corresponding inorganic piezoelectric elements 2. In other words, the plurality of first acoustic matching layers 3 are arranged with respect to the plurality of inorganic piezoelectric elements 2 so that the positions in the X direction, which is the arrangement direction of the plurality of inorganic piezoelectric elements 2, coincide with each other.

Further, the second acoustic matching layer 4 is bonded on the first acoustic matching layer 3. The second acoustic matching layer 4 includes a plurality of first resin layers 41 arranged on the surface of the first acoustic matching layer 3 and arranged in the X direction at the same pitch P as the plurality of inorganic piezoelectric elements 2. And a plurality of organic piezoelectric elements 5 disposed on the plurality of first resin layers 41 and a sheet-like second resin layer 42 disposed on the plurality of organic piezoelectric elements 5. .
The plurality of organic piezoelectric elements 5 have a sheet-like first organic piezoelectric layer 52 and a second organic piezoelectric layer 53 stacked in the Z direction, which is the sound axis direction, with the ground electrode layer 51 interposed therebetween. A plurality of first signal electrode layers 54 which are separated from each other on the surface of the first organic piezoelectric layer 52 opposite to the ground electrode layer 51 and arranged in the X direction, and a second organic piezoelectric body On the surface of the layer 53 opposite to the ground electrode layer 51, a plurality of second signal electrode layers 55 are formed so as to be separated from each other and arranged in the X direction.

The plurality of first signal electrode layers 54 and the plurality of second signal electrode layers 55 have the same pitch as the arrangement pitch P of the plurality of inorganic piezoelectric elements 2 and the X direction that is the arrangement direction of the plurality of inorganic piezoelectric elements 2. The first signal electrode layer 54 and the second signal electrode layer 55 corresponding to each other, the ground electrode layer 51 disposed between them, and the first organic The piezoelectric layer 52 and the second organic piezoelectric layer 53 constitute each organic piezoelectric element 5.
The ground electrode layer 51, the first organic piezoelectric layer 52, and the second organic piezoelectric layer 53 are not divided in the arrangement direction X of the plurality of inorganic piezoelectric elements 2, respectively. It extends over five.

That is, each organic piezoelectric element 5 includes a dedicated first signal electrode layer 54, a ground electrode layer 51 common to the plurality of organic piezoelectric elements 5, a first organic piezoelectric layer 52, and a second organic piezoelectric body. It comprises a layer 53 and a dedicated second signal electrode layer 55. Therefore, the arrangement pitch of the plurality of organic piezoelectric elements 5 is determined only by the arrangement pitch of the first signal electrode layer 54 and the second signal electrode layer 55, and is arranged at the same pitch P as the plurality of inorganic piezoelectric elements 2. Will be.
Further, in each organic piezoelectric element 5, the first piezoelectric element portion 5 a is formed by the first signal electrode layer 54, the first organic piezoelectric layer 52, and the ground electrode layer 51. The second piezoelectric element portion 5 b is formed by the second organic piezoelectric layer 53 and the second signal electrode layer 55. That is, each organic piezoelectric element 5 includes a first piezoelectric element portion 5a and a second piezoelectric element portion 5b that are stacked in the Z direction.

  The plurality of inorganic piezoelectric elements 2, the plurality of first acoustic matching layers 3, the plurality of first resin layers 41, and the plurality of first signal electrode layers 54 are mutually at the same pitch P and in the X direction. The stacked bodies S that are arranged so as to coincide with each other and are laminated in the Z direction from the plurality of inorganic piezoelectric elements 2 to the plurality of first signal electrode layers 54 have a configuration arranged in the X direction. And the 1st isolation | separation part 6 is formed between the laminated bodies S adjacent to each other in the X direction. The first separation portion 6 is formed by filling a filler formed in a groove formed between the stacked bodies S adjacent to each other. Each of the first separation portions 6 extends in the Z direction so as to penetrate each layer from the surface of the first signal electrode layer 54 to the surface 1a portion of the backing material 1, and is a stack arranged in the X direction. The bodies S are separated from each other.

In addition, a second separation portion 7 is formed between the plurality of second signal electrode layers 55 arranged in the X direction. The second separator 7 is filled with a filler in a groove formed from the surface of the second signal electrode layer 55 in contact with the second organic piezoelectric layer 53 to the middle of the second resin layer 42. It is formed by.
Further, an acoustic lens 8 is bonded on the second acoustic matching layer 4.

The inorganic piezoelectric element 21 of the inorganic piezoelectric element 2 is formed of an inorganic material for a piezoelectric body such as a Pb-based perovskite structure oxide. For example, Pb-based piezoelectric ceramic represented by lead zirconate titanate (Pb (Zr, Ti) O ₃ ), or magnesium niobate / lead titanate solid solution (PMN-PT) and zinc niobate / lead titanate It can be formed from a relaxor-type piezoelectric single crystal typified by a solid solution (PZN-PT).
On the other hand, the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 of the organic piezoelectric element 5 are made of an organic material for a piezoelectric material such as a vinylidene fluoride (VDF) material. For example, it can be formed from a polymer piezoelectric element such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride trifluoride ethylene copolymer (P (VDF-TrFE)).

The backing material 1 supports a plurality of inorganic piezoelectric elements 2 and absorbs ultrasonic waves emitted backward, and can be formed from a rubber material such as ferrite rubber.
The first acoustic matching layer 3 is for efficiently allowing ultrasonic waves emitted from the plurality of inorganic piezoelectric elements 2 to enter the subject from the acoustic lens 8. It is formed from a material having an acoustic impedance that is an intermediate value of the acoustic impedance of a living body.
The thickness of the first acoustic matching layer 3 is, for example, the wavelength of the fundamental wave of ultrasonic waves emitted from the plurality of inorganic piezoelectric elements 2 (for example, the maximum sensitivity of the −6 dB band center frequency of the inorganic piezoelectric body 21). It is set to be in the vicinity of a value that satisfies the λ / 4 resonance condition with respect to λ.

  The second acoustic matching layer 4, together with the first acoustic matching layer 3, is for making the ultrasonic waves emitted from the plurality of inorganic piezoelectric elements 2 efficiently enter the subject. The first resin The layer 41 includes a total of four layers including a first organic piezoelectric layer 52, a second organic piezoelectric layer 53, and a second resin layer 42.

The first resin layer 41 and the second resin layer 42 are formed from a resin material having an acoustic impedance close to the acoustic impedance of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53. More specifically, the first resin layer 41 is smaller than the acoustic impedance of the first acoustic matching layer 3 and the acoustic impedance of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53. And the second resin layer 42 is equal to or slightly smaller than the acoustic impedance of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53, In addition, the acoustic impedance of the acoustic lens 8 is set to be higher than the acoustic impedance. The first resin layer 41 and the second resin layer 42 can also be formed from the same material as the material for forming the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53.
The sum of the thicknesses of the four layers of the first resin layer 41, the first organic piezoelectric layer 52, the second organic piezoelectric layer 53, and the second resin layer 42 is, for example, a plurality of inorganic piezoelectric elements. 2 is set in the vicinity of a value satisfying the λ / 4 resonance condition with respect to the wavelength λ of the fundamental wave of the ultrasonic wave emitted from 2.

The filler used in the first separation unit 6 and the second separation unit 7 is for fixing the position and posture of the stacked body S and the second signal electrode layer 55 adjacent to each other. For example, an epoxy resin Formed from.
The acoustic lens 8 narrows the ultrasonic beam using refraction and improves the resolution in the Y direction, which is the elevation direction, and is made of silicon rubber or the like.

Next, the operation of the ultrasonic probe according to the first embodiment will be described.
In operation, for example, the plurality of inorganic piezoelectric elements 2 are used as transducers dedicated to ultrasonic transmission, and the plurality of organic piezoelectric elements 5 are used as transducers dedicated to ultrasonic reception.
When a pulsed or continuous wave voltage is applied between the signal electrode layer 22 and the ground electrode layer 23 of the plurality of inorganic piezoelectric elements 2, the inorganic piezoelectric body 21 of each inorganic piezoelectric element 2 expands and contracts to be pulsed or continuous. Wave ultrasound is generated. These ultrasonic waves enter the subject through the first acoustic matching layer 3, the second acoustic matching layer 4, and the acoustic lens 8, and are combined with each other to form an ultrasonic beam and pass through the subject. Propagate.

  Subsequently, when the ultrasonic echoes propagated and reflected in the subject are incident on the respective organic piezoelectric elements 5 through the acoustic lens 8 and the second resin layer 42, the respective organic piezoelectric elements 5 are caused to enter. The second piezoelectric element portion 5b and the first piezoelectric element portion 5a that are configured respond to the harmonic component of the ultrasonic wave with high sensitivity, and the second organic piezoelectric layer 53 included in the second piezoelectric element portion 5b. Each of the first organic piezoelectric layers 52 included in the first piezoelectric element portion 5a expands and contracts. As a result, an electric signal is generated between the second signal electrode layer 55 of the second piezoelectric element portion 5b and the ground electrode layer 51, and the ground electrode layer 51 of the first piezoelectric element portion 5a and the first signal are generated. An electrical signal is generated between the electrode layers 54 and is output as a received signal.

  The reception signal obtained by the second piezoelectric element unit 5b and the reception signal obtained by the first piezoelectric element unit 5a are added to each other, and a harmonic image can be generated based on the added reception signal. it can. Here, the plurality of inorganic piezoelectric elements 2 and the plurality of organic piezoelectric elements 5 are aligned with each other in the Z direction that is the sound axis direction, that is, the positions of the plurality of inorganic piezoelectric elements 2 in the arrangement direction X are the same. In addition, since they are arranged at the same pitch P, ultrasonic echoes from the subject can be received at the same arrangement position as the transmission position of the ultrasonic beam, and a harmonic image can be generated with high accuracy. Can do.

Here, the first acoustic matching layer 3 has an acoustic impedance that is an intermediate value between the acoustic impedance of the inorganic piezoelectric element 2 and the acoustic impedance of the living body that is the subject, and in the vicinity of a value that satisfies the λ / 4 resonance condition. On the other hand, the first resin layer 41 and the second resin layer 42 of the second acoustic matching layer 4 are formed of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53, respectively. The acoustic impedance has a value close to the acoustic impedance, and the first resin layer 41, the first organic piezoelectric layer 52, the second organic piezoelectric layer 53, and the second resin layer 42 have a thickness of four layers. Since the sum is set in the vicinity of a value satisfying the λ / 4 resonance condition, ultrasonic waves can be transmitted and received efficiently.
In addition, each organic piezoelectric element 5 is formed of a first piezoelectric element portion 5a and a second piezoelectric element portion 5b that are stacked in the Z direction that is the sound axis direction. By connecting the part 5a and the second piezoelectric element part 5b in parallel to each other, the capacitance as the organic piezoelectric element 5 can be increased, and a reception signal by ultrasonic echoes can be efficiently acquired, Noise can be reduced and the S / N ratio of the received signal can be improved.

A plurality of inorganic piezoelectric elements 2 can also be used as transducers for transmitting and receiving ultrasonic waves. In this case, ultrasonic echoes received by the organic piezoelectric element 5 through the acoustic lens 8 and the second resin layer 42 are further transmitted through the first resin layer 41 and the first acoustic matching layer 3, respectively. The light enters the inorganic piezoelectric element 2, and the inorganic piezoelectric body 21 expands and contracts mainly in response to the fundamental wave component of the ultrasonic wave, and generates an electric signal between the signal electrode layer 22 and the ground electrode layer 23.
Based on the reception signal corresponding to the fundamental wave component obtained from the plurality of inorganic piezoelectric elements 2 in this way and the reception signal corresponding to the harmonic component obtained from the organic piezoelectric element 5, the fundamental wave component and the harmonics are obtained. A compound image in which wave components are combined can be generated.

  Also at this time, the plurality of inorganic piezoelectric elements 2 and the plurality of organic piezoelectric elements 5 are aligned in the Z direction, which is the direction of the sound axis, and are arranged at the same pitch P, so that the fundamental wave of the ultrasonic echo The component and the harmonic component can be received at the same arrangement position, and a compound image in which the fundamental wave component and the harmonic component are combined with high accuracy can be generated.

Such an ultrasonic probe can be manufactured as follows.
First, as shown in FIG. 3A, a sheet-like inorganic piezoelectric element layer 91a extending over the entire area of the backing material 1 is bonded onto the surface 1a of the backing material 1 with an adhesive or the like. This inorganic piezoelectric element layer 91a is formed by forming a first conductive layer 92 and a second conductive layer 93 over the entire surface on both sides of an inorganic piezoelectric layer 91 extending over the surface 1a of the backing material 1, respectively. The conductive layer 92 is bonded onto the surface 1 a of the backing material 1.
Next, as shown in FIG. 3B, a sheet-like acoustic matching layer 94 extending over the entire area of the inorganic piezoelectric element layer 91a is formed on the second conductive layer 93 at a temperature of, for example, 80 ° C. to 100 ° C. Join.
Further, a sheet-like first resin layer 95 is bonded on the acoustic matching layer 94. The first resin layer 95 is large enough to extend over the entire surface of the acoustic matching layer 94, and the third conductive layer 96 is formed over the entire surface on the opposite side of the surface facing the acoustic matching layer 94. Pre-formed.

Subsequently, as shown in FIG. 3C, the third conductive layer 96, the first resin layer 95, the acoustic matching layer 94, and the inorganic piezoelectric element layer 91a are diced at a predetermined pitch P. Separate each layer into multiple pieces. At this time, since dicing is performed so as to completely divide each layer from the third conductive layer 96 to the inorganic piezoelectric element layer 91a, each fragment of each divided layer is positioned in the sound axis direction, that is, the Z direction. Aligned. As a result, a plurality of inorganic piezoelectric elements 2 arranged at an arrangement pitch P are formed on the surface 1 a of the backing material 1. A plurality of inorganic piezoelectric elements 2 and a plurality of first piezoelectric elements 2 are formed on each inorganic piezoelectric element 2. Of the acoustic matching layer 3, the plurality of first resin layers 41, and the plurality of first signal electrode layers 54 are formed so as to be aligned in the Z direction. Further, by dicing, a groove 97 extending in the Z direction is formed between the stacked bodies S adjacent to each other in the X direction.
In this way, by dicing each layer from the third conductive layer 96 to the inorganic piezoelectric element layer 91a with the pitch P, each layer is easily separated into a plurality of pieces and each piece of each separated layer is designated as Z. It can be aligned in the direction. The first signal electrode layers 54 of the plurality of organic piezoelectric elements 5 and the signal electrode layers 22 and the ground electrode layers 23 of the plurality of inorganic piezoelectric elements 2 can be accurately aligned with each other.

  Next, as shown in FIG. 3D, the first separation unit 6 that fills the inside of the plurality of grooves 97 formed by dicing and fixes the position and posture of each stacked body S. Of the sheet-like first and second organic piezoelectric layers 52 and 53 laminated on the third conductive layer 96 with the fourth conductive layer 98 interposed therebetween. The organic piezoelectric layer 52 is pressure-bonded at a temperature of about 80 ° C., for example.

  Here, as shown in FIG. 3E, the acoustic lens 8 in which the sheet-like second resin layer 99 and the fifth conductive layer 100 are sequentially formed on the surface is shown in FIG. Dicing is performed from the surface of the fifth conductive layer 100 at the same pitch P as the dicing, thereby dividing the fifth conductive layer 100 at the pitch P in the X direction. At this time, since it is difficult to cut only the thin fifth conductive layer 100, dicing is performed from the surface of the fifth conductive layer 100 to the middle in the thickness direction of the second resin layer 99, Grooves 101 are formed between the adjacent fifth conductive layers 100, and the respective grooves 101 enter the middle of the second resin layer 99.

  Then, as shown in FIG. 3F, after filling the inside of the plurality of grooves 101 with the filler to form the second separation portion 7 that fixes the position of the fifth conductive layer 100, X The fifth conductive layer 100 is bonded onto the surface of the second organic piezoelectric layer 53 while aligning the positions of the third conductive layer 96 and the fifth conductive layer 100 in the direction. At this time, it is desirable to align the third conductive layer 96 and the fifth conductive layer 100 at both ends in the X direction. When the end portion of the third conductive layer 96 in the X direction and the end portion of the backing material 1 coincide with each other, and the end portion of the fifth conductive layer 100 in the X direction and the end portion of the acoustic lens 8 coincide with each other. The positions of the third conductive layer 96 and the fifth conductive layer 100 can be aligned by aligning the end of the backing material 1 and the end of the acoustic lens 8 with each other.

Thereby, the inorganic piezoelectric layer 91, the first conductive layer 92, and the second conductive layer 93 divided by the first separation unit 6 in which the ultrasonic probe shown in FIGS. , The inorganic piezoelectric body 21, the signal electrode layer 22 and the ground electrode layer 23 of the inorganic piezoelectric element 2, and the acoustic matching layer 94, the first resin layer 95, and the third divided by the first separation unit 6, respectively. The conductive layers 96 form the first acoustic matching layer 3, the first resin layer 41, and the first signal electrode layer 54, respectively. In addition, the fourth conductive layer 98, the second resin layer 99, and the fifth conductive layer 100 divided by the second separator 7 are respectively connected to the ground electrode layer 51, the second resin layer 42, and the second conductive layer 100. Two signal electrode layers 55 are formed.

Since the crystallinity of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 gradually decreases as the temperature rises, there is a use upper limit temperature at a temperature considerably lower than the Curie point. For example, when a high temperature of 80 ° C. to 100 ° C. used when laminating each layer such as the acoustic matching layer 94 is directly applied, the first organic piezoelectric layer 52 is formed of a backing material. Each of the first to third conductive layers 96 is stacked and then stacked on the third conductive layer 96, and the acoustic lens 8 and the second lens formed in a separate process shown in FIG. A laminate of the resin layer 99 and the fifth conductive layer 100 is bonded onto the second organic piezoelectric layer 53. For this reason, the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 are exposed to a high temperature, for example, when another layer is laminated or when the filler is filled in the grooves 97 and 101. And depolarization can be suppressed.
Furthermore, since the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 do not exist until the respective layers from the backing material 1 to the third conductive layer 96 are sequentially bonded, these layers are They can be bonded to each other at a high temperature and laminated with a high adhesive force.

For example, the frequency of ultrasonic waves transmitted from the plurality of inorganic piezoelectric elements 2 is about 7 MHz, the acoustic impedance of the first acoustic matching layer 3 is about 8.9 Mrayl (kg / m ² s), and the second acoustic matching layer In the case of producing a linear probe having an acoustic impedance of about 4.0 Mrayl, lead zirconate titanate (Pb (Zr, Ti) O ₃ ) is used as the inorganic piezoelectric body 21 and the thickness thereof is about 190 μm. The thickness of the first acoustic matching layer 3 and the first resin layer 41, the first organic piezoelectric layer 52, the second organic piezoelectric layer 53, and the second constituting the second acoustic matching layer 4 are formed. The sum of the thicknesses of the four resin layers 42 in total can be formed to about 80 μm. Thereby, the plurality of organic piezoelectric elements 5 can be formed with a desired thickness while the second acoustic matching layer 4 satisfies the resonance condition for the plurality of inorganic piezoelectric elements 2.

In this way, each organic piezoelectric element 5 is composed of the first piezoelectric element portion 5a and the second piezoelectric element portion 5b stacked on each other in the Z direction, and the thickness of the first acoustic matching layer 3 and the second The sum of the total thickness of the first resin layer 41, the first organic piezoelectric layer 52, the second organic piezoelectric layer 53, and the second resin layer 42 constituting the acoustic matching layer 4, respectively, By setting so as to satisfy the resonance condition, the reception efficiency of the received signals in the plurality of organic piezoelectric elements 5 is improved while maintaining an excellent acoustic transmittance with respect to the ultrasonic beams transmitted from the plurality of inorganic piezoelectric elements 2. Can be made. Furthermore, the capacitance as the organic piezoelectric element 5 can be increased, and it is possible to efficiently obtain a received signal by ultrasonic echoes, thereby reducing thermal noise and improving the S / N ratio of the received signal. Can do.
In addition, since the plurality of inorganic piezoelectric elements 2 and the plurality of organic piezoelectric elements 5 are arranged so as to be aligned with each other in the Z direction that is the sound axis direction, it is possible to generate high-accuracy harmonic images and compound images. .
Further, since the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 of the organic piezoelectric element 5 are less likely to be exposed to a high temperature when the ultrasonic probe is manufactured, the first organic piezoelectric body. It is possible to prevent the layer 52 and the second organic piezoelectric layer 53 from depolarizing.

Each inorganic piezoelectric element 2 can be divided into a plurality of sub-dies. For example, the inorganic piezoelectric material 21, the signal electrode layer 22, and the ground electrode layer 23 constituting each inorganic piezoelectric element 2 are each divided into a plurality of pieces along the X direction that is the arrangement direction of the plurality of inorganic piezoelectric elements 2. Is done. Thus, by dividing each inorganic piezoelectric element 2 into a plurality of sub-dies, the piezoelectric multiplier of the inorganic piezoelectric element 2 can be improved, and the transmission / reception sensitivity of the ultrasonic probe can be improved.
In order to manufacture such an ultrasonic probe, during the dicing shown in FIG. 3C, the inorganic piezoelectric element layer 91a or each layer from the inorganic piezoelectric element layer 91a to the acoustic matching layer 94 is sounded. The dicing groove may be formed by further dicing in the Z direction which is the axial direction.

Embodiment 2
As shown in FIG. 4, the inorganic piezoelectric element A / D converter 9 is connected to the signal line electrode layer 22 of each inorganic piezoelectric element 2, and the first piezoelectric element portion 5 a of the organic piezoelectric element 5 is connected to the first piezoelectric element portion 5 a. The signal electrode layer 54 and the lead wire from the second signal electrode layer 55 of the second piezoelectric element portion 5b are connected to each other at a connection point A, and the organic piezoelectric element amplifier 10 and the organic piezoelectric element are connected to the connection point A. The A / D converters 11 can be sequentially connected.
Here, the electric capacity of the plurality of organic piezoelectric elements 5 can be increased by connecting the first piezoelectric element portion 5a and the second piezoelectric element portion 5b in parallel to each other. It is desirable to amplify. At this time, in order to prevent the received signal from being attenuated while being transmitted from the organic piezoelectric element 5 to the organic piezoelectric element amplifier 10, the organic piezoelectric element amplifier 10 is connected to the first signal electrode layer 54 of the organic piezoelectric element 5 and It is preferable to connect or connect directly to the vicinity of the second signal electrode layer 55.

  The polarization directions of the first organic piezoelectric layer 52 and the second organic piezoelectric layer 53 along the Z direction, which is the sound axis direction, are opposite to each other, and the first piezoelectric element portion 5a and the second piezoelectric element portion 5a The received signals obtained from the piezoelectric element portion 5b have the same polarity, and can be added to each other at the connection point A in FIG.

  Further, the number of signal lines drawn from the ultrasonic probe can be reduced by disposing the multiplexer in the ultrasonic probe incorporating the ultrasonic probe according to the second embodiment. For example, a multiplexer is disposed after the A / D converter 9 for the inorganic piezoelectric element and the A / D converter 11 for the organic piezoelectric element, and is drawn from the A / D converter 9 for the inorganic piezoelectric element and the A / D converter 11 for the organic piezoelectric element. These two signal lines can be combined into one.

  In the first and second embodiments described above, each organic piezoelectric element 5 has two piezoelectric element portions 5a and 5b stacked on each other in the sound axis direction. However, the present invention is not limited to this. Each organic piezoelectric element 5 can also be configured to have three or more piezoelectric element portions stacked on each other in the sound axis direction. By connecting three or more piezoelectric element portions in parallel to each other, the capacitance as the organic piezoelectric element 5 is increased, and the S / N ratio of the received signal can be improved.

Embodiment 3
In the first and second embodiments, the ultrasonic waves generated by the plurality of inorganic piezoelectric elements 2 are transmitted toward the subject, and the ultrasonic echoes reflected in the subject are the plurality of inorganic piezoelectric elements 2 or the plurality. However, as shown in FIG. 5, by newly providing a light irradiation unit 31 that irradiates the subject with the irradiation light L, the light irradiation unit 31 is directed toward the subject. For example, a plurality of organic piezoelectric elements 5 can receive photoacoustic waves U (ultrasonic waves) induced from the subject by irradiation with irradiation light L. Thereby, what is called photoacoustic imaging (PAI: Photoacoustic Imaging) which images the inside of a subject using a photoacoustic effect can be performed.
The light irradiation unit 31 sequentially irradiates a subject with a plurality of irradiation lights L having different wavelengths, and may be composed of a semiconductor laser (LD), a light emitting diode (LED), a solid-state laser, a gas laser, or the like. it can. For example, the light irradiation unit 31 uses pulsed laser light as the irradiation light L and irradiates the subject with the pulsed laser light while sequentially switching the wavelength for each pulse.

When performing photoacoustic imaging, irradiation light L is irradiated from the light irradiation unit 31 toward the subject, and when the irradiated irradiation light L is irradiated to a predetermined biological tissue V in the subject, the living body The tissue V absorbs the light energy of the irradiation light L and emits a photoacoustic wave U (ultrasonic wave) that is an elastic wave.
For example, the object is sequentially irradiated with irradiation light L having a wavelength of about 750 nm and irradiation light L having a wavelength of about 800 nm from the light irradiation unit 31. Here, oxygenated hemoglobin (hemoglobin combined with oxygen: oxy-Hb) contained in a large amount in human arteries has a higher molecular absorption coefficient than the irradiation light L having a wavelength of 800 nm with respect to the irradiation light L having a wavelength of 750 nm. . On the other hand, deoxygenated hemoglobin (hemoglobin deoxy-Hb not bound to oxygen) contained in a large amount in veins has a lower molecular absorption coefficient for irradiation light L with a wavelength of 750 nm than irradiation light L with a wavelength of 800 nm. For this reason, when the irradiation light L having a wavelength of 800 nm and the irradiation light L having a wavelength of 750 nm are respectively irradiated to an artery and a vein, photoacoustic waves U having an intensity corresponding to the molecular absorption coefficient of the artery and vein are respectively emitted.
The photoacoustic wave U emitted from the artery or vein is received by the plurality of organic noise elements 5 of the ultrasonic probe in the same manner as in the first and second embodiments.

As described above, the ultrasonic probe can be used not only for an ultrasonic image but also for a photoacoustic image, and various ultrasonic diagnosis can be performed by using one ultrasonic probe. It can be carried out.
The photoacoustic wave U induced from the subject by the irradiation of the irradiation light L can be received by the plurality of inorganic piezoelectric elements 2.

  DESCRIPTION OF SYMBOLS 1 Backing material, 1a The surface of a backing material, 2 Inorganic piezoelectric element, 3rd 1st acoustic matching layer, 4th 2nd acoustic matching layer, 5 Organic piezoelectric element, 5a 1st piezoelectric element part, 5b 2nd piezoelectric element Part, 6, 7 Separation part, 8 acoustic lens, 9 A / D converter for inorganic piezoelectric element, 10 amplifier for organic piezoelectric element, 11 A / D converter for organic piezoelectric element, 21 inorganic piezoelectric body, 22 signal electrode layer, 23 Ground electrode layer, 31 light irradiation portion, 41 first resin layer, 42 second resin layer, 51 ground electrode layer, 52 first organic piezoelectric layer, 53 second organic piezoelectric layer, 54 first Signal electrode layer, 55 second signal electrode layer, 91 inorganic piezoelectric layer, 91a inorganic piezoelectric element layer, 92 first conductive layer, 93 second conductive layer, 94 acoustic matching layer, 95 first resin layer, 96 third conductive layer, 97, 10 Groove, 98 the fourth conductive layer, 99 a second resin layer, 100 a fifth conductive layer, P array pitch, L irradiated light, U photoacoustic wave.

Claims (15)

Backing material,
A plurality of inorganic piezoelectric elements arranged on the surface of the backing material;
A first acoustic matching layer disposed on the plurality of inorganic piezoelectric elements;
A second acoustic matching layer disposed on the first acoustic matching layer,
The second acoustic matching layer includes a plurality of organic piezoelectric elements arranged in parallel to the plurality of inorganic piezoelectric elements,
Each of the organic piezoelectric elements has a plurality of piezoelectric element portions stacked on each other in the sound axis direction. The plurality of organic piezoelectric elements are:
Sheet-like first and second organic piezoelectric layers laminated together with a ground electrode layer interposed therebetween;
A plurality of first signal electrode layers arrayed separately from each other on the surface of the first organic piezoelectric layer opposite to the ground electrode layer;
A plurality of second signal electrode layers arranged separately on the surface of the second organic piezoelectric layer opposite to the ground electrode layer;
A plurality of first piezoelectric element portions are formed by the first organic piezoelectric layer, the ground electrode layer, and the plurality of first signal electrode layers,
2. The ultrasonic probe according to claim 1, wherein a plurality of second piezoelectric element portions are formed by the second organic piezoelectric layer, the ground electrode layer, and the plurality of second signal electrode layers. The second acoustic matching layer is
A plurality of first resin layers formed on the surface of the plurality of first signal electrode layers opposite to the first organic piezoelectric layer and disposed on the first acoustic matching layer When,
The ultrasonic probe according to claim 2, further comprising: a sheet-like second resin layer formed on a surface of the plurality of second signal electrode layers opposite to the second organic piezoelectric layer. Child.   The acoustic impedance of the first resin layer has a value greater than or equal to the acoustic impedance of the first and second organic piezoelectric layers, and the acoustic impedance of the second resin layer is the first and second acoustic impedances. The ultrasonic probe according to claim 3, having a value equal to or lower than the acoustic impedance of the organic piezoelectric layer.   The said 1st resin layer and the said 2nd resin layer have an acoustic impedance in the range of +/- 10% with respect to the acoustic impedance of the said 1st and 2nd organic piezoelectric material layer, respectively. Ultrasonic probe.   The ultrasonic probe according to any one of claims 2 to 5, wherein the first and second organic piezoelectric layers are formed of a vinylidene fluoride-based material.   The super structure according to any one of claims 1 to 6, wherein the plurality of inorganic piezoelectric elements and the plurality of organic piezoelectric elements are formed at the same position with respect to the sound axis direction at the same arrangement pitch. Sonic probe. Each of the inorganic piezoelectric elements is
An inorganic piezoelectric layer;
A signal electrode layer disposed on the surface of the inorganic piezoelectric layer;
The ultrasonic probe according to claim 1, further comprising: a ground electrode layer disposed on a back surface of the inorganic piezoelectric layer.   The ultrasonic probe according to claim 8, wherein each of the inorganic piezoelectric elements is divided into a plurality of sub-dies along an arrangement direction of the plurality of inorganic piezoelectric elements.   The ultrasonic probe according to claim 8, wherein the plurality of inorganic piezoelectric layers are formed of a Pb-based perovskite structure oxide.   The ultrasonic probe according to claim 1, further comprising: an acoustic lens disposed on a surface of the second acoustic matching layer opposite to the first acoustic matching layer. .   The ultrasonic probe according to any one of claims 1 to 11, further comprising a plurality of organic piezoelectric element amplifiers directly connected to the plurality of organic piezoelectric elements. It further has a light irradiation unit that irradiates irradiation light toward the subject,
The ultrasonic wave induced from the subject by irradiating the irradiation light from the light irradiation unit is received by the plurality of organic piezoelectric elements or the plurality of inorganic piezoelectric elements. Ultrasonic probe. A sheet-like inorganic piezoelectric layer is bonded to the surface of the backing material via the first conductive layer,
A sheet-like acoustic matching layer is bonded to the surface of the inorganic piezoelectric layer via a second conductive layer,
Bonding a sheet-like first resin layer on the surface of the acoustic matching layer and forming a third conductive layer on the entire surface of the first resin layer;
A plurality of inorganic piezoelectric elements are arrayed by dicing from the third conductive layer to the inorganic piezoelectric layer at a predetermined pitch in the stacking direction, and the third conductive layer is the same as the plurality of inorganic piezoelectric elements. Divided by the pitch of
After filling the divided grooves with resin, the first organic piezoelectric layer of the sheet-like first and second organic piezoelectric layers stacked on each other with the fourth conductive layer interposed therebetween is replaced with the third organic piezoelectric layer. On the surface of the conductive layer of
The fifth conductive layer formed on the surface opposite to the acoustic lens of the sheet-like second resin layer bonded to the acoustic lens is diced at the predetermined pitch, whereby the fifth conductive layer is formed. Dividing the layer at the same pitch as the plurality of inorganic piezoelectric elements;
The fifth conductive layer formed on the surface of the second resin layer while aligning the positions of the third conductive layer and the fifth conductive layer in the arrangement direction of the plurality of inorganic piezoelectric elements. By joining on the surface of the second organic piezoelectric layer, a first piezoelectric element portion comprising the third conductive layer, the first organic piezoelectric layer, and the fourth conductive layer, respectively. The fifth conductive layer, the second organic piezoelectric layer, and the second piezoelectric element portion made of the fourth conductive layer are stacked and arranged at the same pitch as the plurality of inorganic piezoelectric elements. A method of manufacturing an ultrasonic probe, comprising forming a plurality of organic piezoelectric elements.   The method of manufacturing an ultrasonic probe according to claim 14, wherein the alignment of the third conductive layer and the fifth conductive layer is performed at both ends in the arrangement direction of the plurality of inorganic piezoelectric elements.

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