JP2013074375A - Ultrasonic probe and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe in which plural inorganic piezoelectric elements and plural organic piezoelectric elements are stacked to be formed capable of generating an ultrasonic image of high picture quality.SOLUTION: On a surface of a backing material 1, plural inorganic piezoelectric elements 2 having pitches P1 are arrayed to be formed, on plural inorganic piezoelectric elements 2, an acoustic matching layer 3 is extended over whole of the plural inorganic piezoelectric elements 2, and plural organic piezoelectric elements 4 having pitches P2 are arrayed to be formed on the acoustic matching layer 3. The plural organic piezoelectric elements 4 comprise: plural signal electrode layers 42 which contacts a surface of the acoustic matching layer 3; a common organic piezoelectric substance 41 joined onto the plural signal electrode layers 42 and extended over the plural organic piezoelectric elements 4; and a common ground electrode layer 43 joined onto the organic piezoelectric substance 41 and extended over the plural organic piezoelectric elements 4.

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 make a more accurate diagnosis, harmonic imaging that receives and visualizes harmonic components generated by distortion of an ultrasonic waveform due to nonlinearity of a subject is in the spotlight.
As an ultrasonic probe suitable for this harmonic imaging, for example, as disclosed in Patent Document 1, a plurality of inorganic piezoelectric elements using an inorganic piezoelectric material such as lead zirconate titanate (PZT) and polyfluoride are used. A device in which a plurality of organic piezoelectric elements using an organic piezoelectric material such as vinylidene (PVDF) is laminated is 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.

JP 11-155863 A

  A plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements are laminated via an acoustic matching layer in order to efficiently transmit ultrasonic waves. Conventionally, as shown in FIG. The acoustic matching layer is divided into a plurality of parts corresponding to the piezoelectric elements, and the corresponding organic piezoelectric elements are arranged on the divided acoustic matching layers. For this reason, the inorganic piezoelectric element and the organic piezoelectric element are arranged with the same number of channels and the same pitch. As a result, a grating lobe is likely to occur when a high-order harmonic component is received by the organic piezoelectric element, and there is a possibility that the image quality is degraded.

  The present invention has been made to solve such a conventional problem, and enables generation of a high-quality ultrasonic image while a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements are laminated. It is an object of the present invention to provide an ultrasonic probe and a manufacturing method thereof.

  An ultrasonic probe according to the present invention includes a backing material, a plurality of inorganic piezoelectric elements arranged on the surface of the backing material, and disposed over the plurality of inorganic piezoelectric elements and extending over the plurality of inorganic piezoelectric elements. And a plurality of organic piezoelectric elements arranged on the acoustic matching layer.

Preferably, the plurality of organic piezoelectric elements includes a common organic piezoelectric body extending over the plurality of organic piezoelectric elements and a plurality of signal electrodes arranged on a surface of the organic piezoelectric body facing the acoustic matching layer and separated from each other. And a common ground electrode layer disposed on the other surface of the organic piezoelectric body and extending over the plurality of inorganic piezoelectric elements.
The plurality of organic piezoelectric elements may be arranged at a pitch different from the arrangement pitch of the plurality of inorganic piezoelectric elements. For example, the plurality of organic piezoelectric elements can be arranged at a pitch narrower than the arrangement pitch of the plurality of inorganic piezoelectric elements.
The plurality of inorganic piezoelectric elements preferably include a plurality of inorganic piezoelectric bodies separated from each other and a plurality of signal electrode layers and a plurality of ground electrode layers respectively disposed on both surfaces of the plurality of inorganic piezoelectric bodies.
The plurality of inorganic piezoelectric bodies can be formed from lead zirconate titanate or magnesium niobate / lead titanate solid solution, and the organic piezoelectric body can be formed from polyvinylidene fluoride or polyvinylidene fluoride trifluoride ethylene copolymer. .
Furthermore, it is preferable to arrange an acoustic lens on a plurality of organic piezoelectric elements via a protective layer.

  An ultrasonic probe manufacturing method according to the present invention includes an acoustic matching layer in which a plurality of inorganic piezoelectric elements are arrayed on a surface of a backing material and extend over the plurality of inorganic piezoelectric elements on the plurality of inorganic piezoelectric elements. And a plurality of organic piezoelectric elements are arranged on the acoustic matching layer.

Here, the plurality of organic piezoelectric elements are formed by arranging a plurality of signal electrode layers separated from each other on the acoustic matching layer and extending over the plurality of signal electrode layers on the plurality of signal electrode layers. Can be formed, and a ground electrode layer can be formed on the entire surface of the organic piezoelectric material to form an array.
The plurality of signal electrode layers can be arranged and formed by forming a conductive layer on the entire surface of the acoustic matching layer and then dicing the conductive layer at an arbitrary pitch.

  According to the present invention, since the plurality of organic piezoelectric elements are arranged on the acoustic matching layer extending over the plurality of inorganic piezoelectric elements, the plurality of organic piezoelectric elements can be arranged regardless of the arrangement pitch of the plurality of inorganic piezoelectric elements. Therefore, it is possible to realize generation of a high-quality ultrasonic image.

It is sectional drawing which shows the structure of the ultrasonic probe which concerns on embodiment of this invention. It is a fragmentary perspective view which shows the ultrasonic probe which concerns on embodiment. It is sectional drawing which shows the manufacturing method of the ultrasonic probe which concerns on embodiment to process order. It is sectional drawing which shows the structure of the ultrasonic probe which concerns on a modification.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 and 2 show the configuration of an ultrasonic probe according to an embodiment of the present invention.
On the surface of the backing material 1, a plurality of inorganic piezoelectric elements 2 are arranged at a pitch P1. 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. A filler 24 is filled between the adjacent inorganic piezoelectric elements 2.
The acoustic matching layer 3 is bonded on the plurality of inorganic piezoelectric elements 2. The acoustic matching layer 3 extends throughout the plurality of inorganic piezoelectric elements 2 without being divided into a plurality.

  A plurality of organic piezoelectric elements 4 are arranged on the acoustic matching layer 3. The plurality of organic piezoelectric elements 4 have a common organic piezoelectric body 41 extending across the plurality of organic piezoelectric elements 4 without being divided into a plurality of parts. Then, a plurality of signal electrode layers 42 separated from each other corresponding to the plurality of organic piezoelectric elements 4 are joined on the surface of the organic piezoelectric body 41 facing the acoustic matching layer 3, and are opposite to the acoustic matching layer 3. A common ground electrode layer 43 extending over the plurality of organic piezoelectric elements 4 is bonded on the entire surface of the organic piezoelectric body 41. Each signal electrode layer 42 is separated from the adjacent signal electrode layer 42 through a groove 31 formed in the surface portion of the acoustic matching layer 3.

That is, each organic piezoelectric element 4 is formed of a dedicated signal electrode layer 42, and an organic piezoelectric body 41 and a ground electrode layer 43 common to the plurality of organic piezoelectric elements 4. For this reason, the arrangement pitch of the plurality of organic piezoelectric elements 4 is determined only by the arrangement pitch of the plurality of signal electrode layers 42 bonded on the surface of the organic piezoelectric body 41. In this embodiment, the plurality of signal electrode layers 42 are arranged at a pitch P2 that is narrower than the arrangement pitch P1 of the inorganic piezoelectric elements 2, thereby forming a plurality of organic piezoelectric elements 4 having the arrangement pitch P2. ing.
Furthermore, an acoustic lens 6 is bonded on the plurality of organic piezoelectric elements 4 via a protective layer 5.

  The inorganic piezoelectric element 21 of the inorganic piezoelectric element 2 is formed of a piezoelectric ceramic typified by lead zirconate titanate (PZT) or a piezoelectric single crystal typified by magnesium niobate / lead titanate solid solution (PMN-PT). Yes. On the other hand, the organic piezoelectric element 41 of the organic piezoelectric element 4 is formed of a polymer piezoelectric element such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride trifluoride ethylene copolymer.

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 acoustic matching layer 3 is for efficiently allowing the ultrasonic beams from the plurality of inorganic piezoelectric elements 2 to enter the subject. The acoustic matching layer 3 has an intermediate value between the acoustic impedance of the inorganic piezoelectric element 2 and the acoustic impedance of the living body. It is formed from a material having impedance.
The protective layer 5 protects the ground electrode layer 43 of the organic piezoelectric element 4 and is formed of, for example, polyvinylidene fluoride (PVDF).
The acoustic lens 6 narrows the ultrasonic beam using refraction and improves the resolution in the elevation direction, and is made of silicon rubber or the like.

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 4 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 acoustic matching layer 3, the organic piezoelectric element 4, the protective layer 5, and the acoustic lens 6, and are combined with each other to form an ultrasonic beam and propagate through the subject. .
When an ultrasonic echo from the subject enters each organic piezoelectric element 4 via the acoustic lens 6 and the protective layer 5, the organic piezoelectric body 41 expands and contracts in response to the harmonic component of the ultrasonic wave with high sensitivity, and the signal An electrical signal is generated between the electrode layer 42 and the ground electrode layer 43 and is output as a received signal.
A harmonic image can be generated based on the reception signals output from the plurality of organic piezoelectric elements 4.

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 4 via the acoustic lens 6 and the protective layer 5 are further incident on the respective inorganic piezoelectric elements 2 via the organic piezoelectric element 4 and the acoustic matching layer 3, and are inorganic. The 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 wave component obtained from the organic piezoelectric element 4, the fundamental wave component and the harmonics are obtained. A compound image in which wave components are combined can be generated.

  At this time, since the plurality of organic piezoelectric elements 4 have an arrangement pitch P2 narrower than the arrangement pitch P1 of the plurality of inorganic piezoelectric elements 2, even if the organic piezoelectric element 4 receives higher-order harmonic components. Therefore, the grating lobe is hardly generated, and therefore, a high-quality ultrasonic image can be generated.

Such an ultrasonic probe can be manufactured as follows.
First, as shown in FIG. 3 (A), a conductive material 72 and 73 formed on both surfaces of the inorganic piezoelectric material 71 extending over the entire surface of the backing material 1, respectively, are bonded with an adhesive or the like. Bond on the surface of 1.
Next, as shown in FIG. 3B, by dicing the inorganic piezoelectric body 71 and the conductive layers 72 and 73 at a pitch P1, a plurality of inorganic substances arranged at an arrangement pitch P1 on the surface of the backing material 1 The piezoelectric element 2 is formed. At this time, in order to completely divide the conductive layer 72 located between the inorganic piezoelectric body 71 and the backing material 1, dicing is performed until reaching the surface portion of the backing material 1. It will be separated from the adjacent inorganic piezoelectric element 2 through the groove 25.

Thus, the filling material 24 is filled in the groove 25 formed between the adjacent inorganic piezoelectric elements 2, and as shown in FIG. 3C, the positions and postures of the plurality of inorganic piezoelectric elements 2. Then, the acoustic matching layer 3 is bonded onto the plurality of inorganic piezoelectric elements 2. The acoustic matching layer 3 has a size sufficient to extend over the whole of the plurality of inorganic piezoelectric elements 2, and is electrically conductive on the entire surface of the acoustic matching layer 3 opposite to the surface facing the plurality of inorganic piezoelectric elements 2. Layer 74 is pre-formed.
Next, as shown in FIG. 3D, the conductive layer 74 is diced at a pitch P2, thereby arranging the conductive layer 74 on the surface of the acoustic matching layer 3 at an arrangement pitch P2 corresponding to the plurality of organic piezoelectric elements 4. A plurality of signal electrode layers 42 are formed. At this time, in order to completely divide the conductive layer 74 at the pitch P2, dicing is performed until reaching the surface portion of the acoustic matching layer 3, and each signal electrode layer 42 is adjacent to the signal electrode layer via the groove 31. It will be divided from 42.

Further, as shown in FIG. 3E, an organic piezoelectric body 41 is bonded on the plurality of signal electrode layers 42 by a conductive adhesive or the like. The organic piezoelectric body 41 has a size sufficient to extend over the whole of the plurality of signal electrode layers 42, and is grounded on the entire surface of the organic piezoelectric body 41 opposite to the surface facing the plurality of signal electrode layers 42. An electrode layer 43 is formed in advance. Thus, a plurality of organic piezoelectric elements 4 arranged at the arrangement pitch P2 are formed.
Thereafter, the acoustic lens 6 is bonded onto the ground electrode layer 43 of the plurality of organic piezoelectric elements 4 via the protective layer 5, whereby the ultrasonic probe shown in FIGS. 1 and 2 is manufactured.

Thus, the acoustic matching layer 3 is not divided into a plurality of parts and has a size that extends only over the whole of the plurality of inorganic piezoelectric elements 2, and the plurality of organic piezoelectric elements 4 includes the plurality of organic piezoelectric elements 4. Since the common organic piezoelectric element 41 and the ground electrode layer 43 extending over the organic piezoelectric element 4 are provided, it is extremely easy only by dicing the conductive layer 74 shown in FIG. 3D at an arbitrary pitch. The arrangement pitch P2 of the plurality of organic piezoelectric elements 4 can be freely set.
The arrangement pitch P <b> 2 of the plurality of organic piezoelectric elements 4 is determined only by the dicing pitch of the conductive layer 74 without being restricted by the arrangement pitch P <b> 1 of the plurality of inorganic piezoelectric elements 2.
For this reason, it is possible to easily manufacture an ultrasonic probe having a structure optimal for a purpose of use and the like and generate a high-quality ultrasonic image.

  In addition, although the several signal electrode layer 42 was formed by dicing the conductive layer 74 currently formed on the whole surface of the acoustic matching layer 3, it is not restricted to this, For example, on the whole surface of the acoustic matching layer 3 A plurality of signal electrode layers 42 can be formed by patterning the conductive layer at an arbitrary pitch.

In addition, the acoustic matching layer 3 in which the conductive layer 74 is formed in advance on the surface is bonded onto the plurality of inorganic piezoelectric elements 2. 3 may be bonded, and then the conductive layer 74 may be formed on the surface of the acoustic matching layer 3.
Similarly, the organic piezoelectric body 41 having the ground electrode layer 43 formed in advance on the surface is bonded on the plurality of signal electrode layers 42. After the organic piezoelectric body 41 is bonded on the plurality of inorganic piezoelectric elements 2, The ground electrode layer 43 may be formed on the surface of the organic piezoelectric body 41.

  The plurality of organic piezoelectric elements 4 do not necessarily have to be arranged at a pitch narrower than the arrangement pitch P1 of the plurality of inorganic piezoelectric elements 2. For example, as shown in FIG. They can also be arranged with the same arrangement pitch P1 as the piezoelectric elements 2. Further, the plurality of organic piezoelectric elements 4 may be arranged at a pitch wider than the arrangement pitch P1 of the plurality of inorganic piezoelectric elements 2.

  1 backing material, 2 inorganic piezoelectric element, 3 acoustic matching layer, 4 organic piezoelectric element, 5 protective layer, 6 acoustic lens, 21 inorganic piezoelectric body, 22 signal electrode layer, 23 ground electrode layer, 24 filler, 25, 31 groove , 41 Organic piezoelectric material, 42 Signal electrode layer, 43 Ground electrode layer, 71 Inorganic piezoelectric material, 72 to 74 conductive layer, P1 Arrangement pitch of a plurality of inorganic piezoelectric elements, P2 Arrangement pitch of a plurality of organic piezoelectric elements.

Claims (10)

Backing material,
A plurality of inorganic piezoelectric elements arranged on the surface of the backing material;
An acoustic matching layer disposed on the plurality of inorganic piezoelectric elements and extending over the plurality of inorganic piezoelectric elements;
An ultrasonic probe comprising: a plurality of organic piezoelectric elements arranged on the acoustic matching layer. The plurality of organic piezoelectric elements are:
A common organic piezoelectric body extending across the plurality of organic piezoelectric elements;
A plurality of signal electrode layers arranged on a surface of the organic piezoelectric body facing the acoustic matching layer and separated from each other;
The ultrasonic probe according to claim 1, further comprising: a common ground electrode layer disposed on the other surface of the organic piezoelectric body and extending over the plurality of inorganic piezoelectric elements.   The ultrasonic probe according to claim 1, wherein the plurality of organic piezoelectric elements are arranged at a pitch different from an arrangement pitch of the plurality of inorganic piezoelectric elements.   The ultrasonic probe according to claim 3, wherein the plurality of organic piezoelectric elements are arranged at a pitch narrower than an arrangement pitch of the plurality of inorganic piezoelectric elements. The plurality of inorganic piezoelectric elements are:
A plurality of inorganic piezoelectric bodies separated from each other;
The ultrasonic probe according to claim 1, further comprising: a plurality of signal electrode layers and a plurality of ground electrode layers respectively disposed on both surfaces of the plurality of inorganic piezoelectric bodies.   The plurality of inorganic piezoelectric bodies are made of lead zirconate titanate or magnesium niobate / lead titanate solid solution, and the organic piezoelectric body is made of polyvinylidene fluoride or polyvinylidene fluoride trifluoride ethylene copolymer. The ultrasonic probe as described in any one of -5.   The ultrasonic probe according to any one of claims 1 to 6, further comprising an acoustic lens disposed on the plurality of organic piezoelectric elements via a protective layer. A plurality of inorganic piezoelectric elements are arrayed on the surface of the backing material,
Bonding an acoustic matching layer extending over the plurality of inorganic piezoelectric elements on the plurality of inorganic piezoelectric elements,
A method of manufacturing an ultrasonic probe, comprising: arranging a plurality of organic piezoelectric elements on the acoustic matching layer. The plurality of organic piezoelectric elements are:
A plurality of signal electrode layers separated from each other on the acoustic matching layer;
Bonding an organic piezoelectric body extending over the plurality of signal electrode layers on the plurality of signal electrode layers,
The method for manufacturing an ultrasonic probe according to claim 8, wherein an array is formed by forming a ground electrode layer on the entire surface of the organic piezoelectric body.   The ultrasonic probe according to claim 9, wherein the plurality of signal electrode layers are formed by forming a conductive layer on the entire surface of the acoustic matching layer and then dicing the conductive layer at an arbitrary pitch. Manufacturing method.

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