Ultrasonic probe

Abstract

To provide an ultrasonic probe capable of generating high-definition ultrasonic images while suppressing the number of signal lines for operation.SOLUTION: An ultrasonic probe is such that: a plurality of piezoelectric devices (3) aligned in an azimuth direction are divided into a plurality of division element portions (31) of 4 or more and 10 or less in an elevation direction; a difference between a maximal value and a minimum value of an aspect ratio represented by a ratio of a thickness (Lz1) to a length (Ly1) in the elevation direction of the division element portion is in a range of 10% to an average value of the aspect ratios in the plurality of division element portions; an alignment pitch (P1) in the elevation direction of the plurality of division element portions is larger than a wavelength of ultrasonic waves determined by center frequency of the ultrasonic probe; and signal electrode layers (3A) of two or more division element portions (31C) arranged in the center in the elevation direction adjacently to each other among the plurality of division element portions are electrically connected.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ultrasonic probe, and more particularly to an ultrasonic probe in which a plurality of piezoelectric elements arranged in the azimuth direction are each divided into a plurality of divided element portions in the elevation direction. [Background technology]

[0002] Conventionally, ultrasonic diagnostic devices using ultrasonic images have been put to practical use in the medical field. In general, this type of ultrasonic diagnostic device transmits ultrasonic beams from an ultrasonic probe toward a subject, receives ultrasonic echoes from the subject with the ultrasonic probe, and generates ultrasonic images by electrically processing the received signals.

[0003] As an ultrasonic probe, for example, a one-dimensional array type probe in which multiple piezoelectric elements are linearly arranged in the azimuth direction is used. By adjusting the delay amount for the multiple piezoelectric elements and driving them, the depth of the transmission focus of the ultrasonic beam can be electronically varied on the tomographic plane along the azimuth direction. However, the elevation direction is often a fixed focus determined by an acoustic lens placed in front of the probe.

[0004] In contrast, as disclosed in Patent Documents 1 and 2, by using a two-dimensional array type probe in which multiple piezoelectric elements are arranged two-dimensionally, it becomes possible to adjust the depth of the transmission focus of each ultrasonic beam on a slice plane along any direction. However, in a two-dimensional array type probe, the number of piezoelectric elements increases significantly, and therefore many signal lines are required to drive the probe, and the cable connecting the ultrasonic probe to the device body becomes thicker and heavier, and the cable becomes more rigid, which increases the burden on the user who operates the ultrasonic diagnostic device. Furthermore, this inevitably increases the manufacturing cost of the ultrasonic diagnostic device and complicates the processing circuit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 07-131895 [Patent Document 2] Japanese Patent Application Publication No. 03-243099 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, a probe called a 1.5-dimensional array type probe is sometimes used, in which a plurality of piezoelectric elements arranged in the azimuth direction are each divided into about 3 to 5 element portions in the elevation direction. In this 1.5-dimensional array probe, by dividing the piezoelectric elements in the elevation direction, the depth of the transmission focus of the ultrasonic beam can be electronically varied in the elevation direction as well, enabling the generation of high-resolution ultrasonic images regardless of depth while reducing the number of signal lines used to drive the probe.

[0007] In such a 1.5-dimensional array type probe, the division width of the piezoelectric element in the elevation direction is usually determined taking into consideration the sensitivity of the probe, the beam shape (F value), etc., so that there may be a difference of several times in the aspect ratio, which is expressed by the ratio of the thickness to the length in the elevation direction of each divided element part. If a difference in aspect ratio occurs among multiple element portions arranged in the elevation direction, the sound speeds will be different, and the sensitivity band shapes of each element portion will differ, which may make it impossible to generate a high-resolution ultrasound image.

[0008] The present invention has been made to solve such conventional problems, and has an object to provide an ultrasonic probe that can generate high-resolution ultrasonic images while reducing the number of signal lines used for driving. [Means for solving the problem]

[0009] The above object can be achieved by the following configuration. [1] An ultrasonic probe in which a plurality of piezoelectric elements are arranged in an array along an azimuth direction on a backing material, Each of the plurality of piezoelectric elements is made of a laminate in which a signal electrode layer, a piezoelectric body portion, and a ground electrode layer are laminated in this order on a surface of a backing material, Each piezoelectric element is divided into a plurality of divided element portions, the number of which is 4 or more and 10 or less, in the elevation direction; a difference between a maximum value and a minimum value of an aspect ratio represented by a ratio of a thickness to a length in an elevation direction of each of the plurality of divided element portions is within a range of 10% of an average value of the aspect ratios of the plurality of divided element portions; The arrangement pitch of the plurality of divided element portions in the elevation direction is greater than the wavelength of an ultrasonic wave determined by the center frequency of the ultrasonic probe, An ultrasonic probe in which, among a plurality of divided element portions, the signal electrode layers of at least two divided element portions that are arranged in the center in the elevation direction and adjacent to each other are electrically connected to each other. [2] A wiring board having a conductive pattern is disposed between the plurality of piezoelectric elements and the backing material; The ultrasonic probe according to claim [1], wherein the signal electrode layers and ground electrode layers of the multiple piezoelectric elements are each led out via a conductive pattern of the wiring board. [3] An ultrasonic probe according to [2], wherein each of the multiple divided element portions is divided in the elevation direction via a dividing groove extending from the ground electrode layer to the signal electrode layer. [4] An ultrasonic probe according to [3], in which the dividing groove extends into the interior of the wiring substrate. [5] An ultrasonic probe according to [3] or [4], in which an acoustic matching layer is laminated on the ground electrode layers of the multiple piezoelectric elements. [6] An ultrasonic probe according to [5], in which the dividing groove extends into the interior of the acoustic matching layer. [7] The ultrasonic probe according to any one of [3] to [6], wherein the dividing groove has a groove width in the elevation direction of 10 μm or more and 30 μm or less. [8] An ultrasonic probe according to [7], wherein the dividing groove is filled with a filler. [9] An ultrasonic probe as described in [2], in which two or more central divided element portions are mechanically separated in the elevation direction while a portion of the piezoelectric body and a signal electrode layer are connected to each other.

[10] The piezoelectric portion has a first surface in contact with the signal electrode layer and a second surface in contact with the ground electrode layer, The ultrasonic probe according to [9], wherein the piezoelectric portions of the two or more central divided element portions are adjacent to each other in the elevation direction via a dividing groove extending from the second surface to the first surface.

[11] An ultrasonic probe according to

[10] , wherein the dividing groove has a depth dimension greater than 90% of the thickness of the piezoelectric body.

[12] An ultrasonic probe according to

[10] or

[11] , wherein the dividing groove has a groove width in the elevation direction of 10 μm or more and 30 μm or less.

[13] The ultrasonic probe according to

[12] , wherein the dividing grooves are filled with a filler. Effect of the Invention

[0010] According to this invention, each of the multiple piezoelectric elements is composed of a laminate in which a signal electrode layer, a piezoelectric body portion, and a ground electrode layer are sequentially stacked on the surface of a backing material, and each piezoelectric element is divided into four or more divided element portions in the elevation direction, the difference between the maximum and minimum aspect ratios represented by the ratio of the thickness to the elevation length of each of the multiple divided element portions is within a range of 10% of the average aspect ratios of the multiple divided element portions, the arrangement pitch of the multiple divided element portions in the elevation direction is greater than the wavelength of ultrasound determined by the central frequency of the ultrasonic probe, and the signal electrode layers of at least two divided element portions that are located in the center of the elevation direction and adjacent to each other among the multiple divided element portions are electrically connected to each other, so that it is possible to generate high-definition ultrasonic images while reducing the number of signal lines for driving. [Brief description of the drawings]

[0011] [Figure 1] 1 is a partial perspective view showing an ultrasonic probe according to a first embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view taken along an elevation direction of an ultrasonic probe according to a first embodiment of the present invention. [Diagram 3] 13 is a graph showing a simulation result in which the frequency band of sensitivity is calculated when the aspect ratio of a piezoelectric element is changed. [Figure 4] 5 is a flowchart showing a method for manufacturing the ultrasound probe according to the first embodiment of the present invention. [Diagram 5] 10 is a cross-sectional view taken along an elevation direction of an ultrasonic probe according to a second embodiment of the present invention. FIG. [Figure 6] FIG. 11 is a cross-sectional view taken along the elevation direction of an ultrasonic probe according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a cross-sectional view taken along the elevation direction of an ultrasonic probe according to a fourth embodiment of the present invention. [Figure 8] FIG. 11 is a cross-sectional view taken along the elevation direction of an ultrasonic probe according to a fifth embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following description of the components will be given based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, the terms "same" and "identical" include a generally acceptable margin of error in the technical field.

[0013] First embodiment 1 shows the configuration of an ultrasonic probe PB1 according to a first embodiment of the present invention. The ultrasonic probe PB1 has a configuration in which a backing material 1, a wiring board 2, a plurality of piezoelectric elements 3, a conductive layer 4, and an acoustic matching layer 5 are laminated in this order in the lamination direction. The backing material 1 is a flat plate-like member extending over the entire length and width of the ultrasonic probe PB1, and a wiring board 2 extends on the surface of the backing material 1 and over the entire surface of the backing material 1.

[0014] The multiple piezoelectric elements 3 arranged on the wiring board 2 are arranged in an array along the azimuth direction, and dividing grooves G1 extending in the elevation direction and stacking direction are formed between adjacent piezoelectric elements 3, and the dividing grooves G1 are filled with a filler 6. Also, each of the multiple piezoelectric elements 3 arranged in the azimuth direction is divided into four divided element portions 31 in the elevation direction, and dividing grooves G2 extending in the azimuth direction and stacking direction are formed between adjacent divided element portions 31, and the dividing grooves G2 are filled with a filler 6.

[0015] For convenience, the azimuth direction in which the flat backing material 1 extends along the XY plane and the multiple piezoelectric elements 3 are arranged is referred to as the X direction, the elevation direction in which each piezoelectric element 3 is divided into four divided element portions 31 is referred to as the Y direction, and the stacking direction from the backing material 1 toward the acoustic matching layer 5 is referred to as the +Z direction.

[0016] A conductive layer 4 extending along the XY plane is disposed on the plurality of piezoelectric elements 3, and further, an acoustic matching layer 5 extending along the XY plane is disposed on the conductive layer 4. The acoustic matching layer 5 has a structure in which a first acoustic matching layer 5A, a second acoustic matching layer 5B and a third acoustic matching layer 5C are laminated in this order on the conductive layer 4. Each of the dividing grooves G1 and G2 in the plurality of piezoelectric elements 3 extends from the boundary between the piezoelectric element 3 and the conductive layer 4 to the inside of the wiring board 2 in the Z direction.

[0017] The backing material 1 supports multiple piezoelectric elements 3 via a wiring board 2 and absorbs ultrasonic waves emitted from the multiple piezoelectric elements 3 in the -Z direction, which is behind the ultrasonic probe PB1, and is made of a rubber material such as ferrite rubber. The wiring board 2 arranged on the backing material 1 is made of, for example, an FPC (Flexible Printed Circuit) and, although not shown, has a number of conductive patterns corresponding to all of the divided element portions 31 that are divided into four pieces in the elevation direction from each of the multiple piezoelectric elements 3. The conductive layer 4 disposed on the plurality of piezoelectric elements 3 forms a common ground potential layer for all the divided element portions 31 .

[0018] The acoustic matching layer 5 is a layer for matching the acoustic impedance between the piezoelectric element 3 and the subject to facilitate the incidence of ultrasonic waves into the subject. The acoustic matching layer 5 can be formed of a material having an acoustic impedance smaller than that of the piezoelectric element 3 and larger than that of the subject. For example, by making the acoustic impedance of the second acoustic matching layer 5B smaller than that of the first acoustic matching layer 5A and making the acoustic impedance of the third acoustic matching layer 5C smaller than that of the second acoustic matching layer 5B, a layer structure is formed in which the acoustic impedance decreases stepwise from the piezoelectric element 3 toward the subject.

[0019] The acoustic matching layer 5 is not limited to being composed of three layers, namely, the first acoustic matching layer 5A, the second acoustic matching layer 5B and the third acoustic matching layer 5C, but may be composed of two or less layers or four or more layers. The filler 6 filled in the dividing grooves G1 and G2 is intended to fix the positions and postures of the piezoelectric elements 3 adjacent to each other in the X direction and the divided element portions 31 adjacent to each other in the Y direction, and for example, epoxy resin, silicone rubber, etc. can be used as the filler 6.

[0020] As shown in FIG. 2, the piezoelectric element 3 is formed of a laminate in which a signal electrode layer 3A, a piezoelectric portion 3B, and a ground electrode layer 3C are laminated in this order on the wiring board 2.

[0021] The piezoelectric part 3B is made of a known piezoelectric material, expands and contracts when a voltage is applied to emit ultrasonic waves, and expands and contracts when a so-called ultrasonic echo is received from the outside to generate an electric signal. Examples of the piezoelectric material include piezoelectric ceramics such as PZT (Lead Zirconate Titanate), polymeric piezoelectric elements such as PVDF (Poly Vinylidene Di Fluoride), and piezoelectric single crystals such as PMN-PT (Lead Magnesium Niobate-Lead Titanate).

[0022] The signal electrode layer 3A is used to apply a voltage to the piezoelectric portion 3B and to extract an electric signal generated when the piezoelectric portion 3B expands and contracts upon receiving so-called ultrasonic echoes. The ground electrode layer 3C is used to set the reference potential of the piezoelectric portion 3B to a predetermined ground potential. The signal electrode layer 3A and the ground electrode layer 3C are each made of a thin metal film formed by, for example, sputtering on the -Z direction surface and the +Z direction surface of the piezoelectric portion 3B.

[0023] The four divided element portions 31 divided in the elevation direction have almost the same aspect ratio R. Here, the aspect ratio R is represented by the ratio of the thickness Lz1 in the Z direction to the length Ly1 in the elevation direction of each divided element portion 31. Specifically, the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratio R of the four divided element portions 31 divided in the elevation direction is set to be within a range of 10% of the average value Rav of the aspect ratios R of the four divided element portions 31.

[0024] Figure 3 shows the results of a simulation in which the frequency band of the sensitivity of a piezoelectric element is calculated when the aspect ratio R of the piezoelectric element is changed. In Figure 3, curve C1 represents the band shape of a piezoelectric element with an aspect ratio R = 0.05, and curve C2 represents the band shape of a piezoelectric element with an aspect ratio R = 0.025.

[0025] As shown in Fig. 3, when the aspect ratio R of the piezoelectric element is different, the sound speed in the piezoelectric element is different, and this causes a difference in the frequency band shape of the sensitivity. Therefore, if there is a difference of a certain degree or more in the aspect ratio R of the four divided element portions 31 divided in the elevation direction, it may not be possible to generate a high-definition ultrasonic image along the elevation direction.

[0026] However, in the ultrasonic probe PB1 according to the first embodiment, the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratio R of the four divided element portions 31 divided in the elevation direction is set to be within a range of 10% of the average value Rav of the aspect ratios R of the four divided element portions 31. Therefore, the frequency band shapes of the sensitivity in the four divided element portions 31 are approximately equal, making it possible to generate a high-resolution ultrasonic image along the elevation direction.

[0027] In order to make the frequency band shapes of the sensitivities in the four divided element portions 31 more uniform and further improve the resolution of the ultrasonic image along the elevation direction, it is preferable to set the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratios R of the four divided element portions 31 to be within, for example, 5% of the average value Rav of the aspect ratios R of the four divided element portions 31. By designing the ultrasonic probe PB1 so that the four divided element portions 31 have the same aspect ratio R and manufacturing the ultrasonic probe PB1 with the manufacturing tolerance suppressed to within, for example, 5%, the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratio R can be set within 5% of the average value Rav.

[0028] Also, as shown in FIG. 2, of the four divided element portions 31 divided in the elevation direction, the signal electrode layers 3A of the two end divided element portions 31E arranged at both ends in the elevation direction are both connected to one conductive pattern W1 of the wiring board 2, and these two divided element portions 31E are configured to be driven simultaneously by a common driving voltage via the conductive pattern W1. Furthermore, of the four divided element portions 31 divided in the elevation direction, the signal electrode layers 3A of the two central divided element portions 31C are both connected to a conductive pattern W2 that is separate from the conductive pattern W1 of the wiring board 2, and these two divided element portions 31C are configured to be driven simultaneously by a common driving voltage via the conductive pattern W2.

[0029] By adjusting the delay amount for the two end element portions 31E and simultaneously driving the two central element portions 31C, the depth of the transmission focus of the ultrasonic beam can be electronically varied in the tomographic plane along the elevation direction. In this way, in the ultrasonic probe PB1 according to the first embodiment, the depth of the transmission focus of the ultrasonic beam is electronically variable in the elevation direction, but the ultrasonic beam is not steered in the elevation direction.

[0030] Here, when steering the ultrasonic beam at an angle θ, in order to suppress the occurrence of so-called grating lobes, the wavelength of the ultrasonic wave emitted from the ultrasonic probe PB1 is defined as λ, and the arrangement pitch P of the piezoelectric elements arranged in an array is defined as follows: P<λ / (1+|sinθ|) In other words, the arrangement pitch P of the piezoelectric elements must be smaller than the wavelength of the ultrasonic wave. For example, when steering at an angle of 45 degrees, P<0.6λ It becomes.

[0031] Generally, in a two-dimensional array probe, the ultrasonic beam is steered in both the azimuth and elevation directions, so the arrangement pitch of the piezoelectric elements in both the azimuth and elevation directions must be smaller than the wavelength of the ultrasonic waves emitted from the probe. In the ultrasonic probe PB1 according to the first embodiment, in order to enable steering of the ultrasonic beam while suppressing the occurrence of grating lobes in the cross-sectional plane along the azimuth direction, it is desirable to set the arrangement pitch of the piezoelectric elements 3 in the azimuth direction to a value smaller than the wavelength of the ultrasonic waves.

[0032] However, in the ultrasonic probe PB1 according to the first embodiment, since the ultrasonic beam is not steered in the elevation direction, it is not necessary to suppress the occurrence of grating lobes. Therefore, the arrangement pitch P1 of the four divided element portions 31 in the elevation direction is set to a value larger than the wavelength determined by the central frequency of the ultrasonic waves emitted from the ultrasonic probe PB1. This makes it possible to manufacture the ultrasonic probe PB1 more easily than a two-dimensional array type probe, for example, in terms of dividing the divided element portions 31 into four in the elevation direction and aligning the divided element portions 31 with the conductive patterns W1 and W2 of the wiring board 2.

[0033] Further, the dividing groove G2 dividing the adjacent divided element portions 31 has a groove width F1 in the elevation direction of 10 μm or more and 30 μm or less, preferably 20 μm or less. By reducing the groove width F1 of the dividing groove G2, when the overall length of the ultrasonic probe PB1 in the elevation direction is kept constant, a divided element portion 31 that is long in the elevation direction can be secured, thereby improving the sensitivity of the ultrasonic probe PB1.

[0034] The divided element portion 31 in the ultrasonic probe PB1 according to the first embodiment is formed to have, for example, a length Ly1 of 1 mm in the elevation direction, a length Lx1 of 0.07 mm in the azimuth direction, and a thickness Lz1 of 0.1 mm in the Z direction.

[0035] Next, a method for manufacturing the ultrasonic probe PB1 according to the first embodiment will be described with reference to the flow chart of FIG. First, in step S1, the wiring board 2 is placed on the surface of the backing material 1. The wiring board 2 is joined to the backing material 1 by, for example, an adhesive or the like. Next, in step S2, a laminate is formed by sequentially laminating the signal electrode layer 3A, the piezoelectric body portion 3B, and the ground electrode layer 3C on the wiring board 2. The signal electrode layer 3A, the piezoelectric body portion 3B, and the ground electrode layer 3C are bonded together by, for example, an adhesive or the like.

[0036] In step S3, the laminate is diced to form a plurality of dividing grooves G1 extending along the Y direction and the Z direction, thereby forming a plurality of piezoelectric elements 3 arranged in the X direction. In the following step S4, each piezoelectric element 3 is diced to form a plurality of dividing grooves G2 extending along the X direction and the Z direction, thereby dividing the piezoelectric element 3 into a plurality of divided element portions 31 arranged in the Y direction. Both of the dividing grooves G1 and G2 extend from the ground electrode layer 3C of the piezoelectric element 3 to the inside of the wiring board 2 in the Z direction.

[0037] Furthermore, in step S5, the dividing grooves G1 arranged between the plurality of piezoelectric elements 3 and the dividing grooves G2 arranged between the plurality of divided element portions 31 are filled with the filler 6, respectively. Next, in step S6, a conductive layer 4 is formed on the laminate, and then in step S7, an acoustic matching layer 5 is formed on the conductive layer 4. Here, the conductive layer 4 and the acoustic matching layer 5 are arranged so as to cover all of the plurality of piezoelectric elements 3 arranged in the X direction and the plurality of divided element portions 31 arranged in the Y direction. The conductive layer 4 is formed, for example, by attaching a metal foil onto the laminate, and the acoustic matching layer 5 is formed, for example, by sequentially bonding a first acoustic matching layer 5A, a second acoustic matching layer 5B and a third acoustic matching layer 5C at a temperature of 80°C to 100°C.

[0038] In this manner, as shown in FIG. 1, an ultrasonic probe PB1 is manufactured in which a plurality of piezoelectric elements 3 are arranged in the X direction, which is the azimuth direction, and each piezoelectric element 3 is divided into a plurality of divided element portions 31 in the Y direction, which is the elevation direction.

[0039] A plurality of conductive patterns W1, W2 corresponding to the plurality of piezoelectric elements 3 and the plurality of divided element portions 31 are formed in advance on the wiring board 2, a laminate is formed on the wiring board 2 in step S2, and the laminate is diced in steps S3 and S4, so that the plurality of divided element portions 31 separated from each piezoelectric element 3 are disposed on the corresponding conductive patterns W1, W2. As a result, the signal electrode layer 3A of each divided element portion 31 is bonded and electrically connected to the corresponding conductive patterns W1, W2 of the wiring board 2.

[0040] In this way, of the four divided element portions 31 divided in the elevation direction, the signal electrode layers 3A of the two end divided element portions 31E located at both ends in the elevation direction are both connected to the conductive pattern W1 of the wiring board 2, and the signal electrode layers 3A of the two divided element portions 31C located in the center in the elevation direction are both connected to the conductive pattern W2 of the wiring board 2.

[0041] In addition, the ground electrode layers 3C of all the divided element portions 31 in the ultrasonic probe PB1 are each joined to the conductive layer 4 and electrically connected to the conductive layer 4, and further, the conductive layer 4 is connected to the ground pattern of the wiring board 2 via a resin film with a conductive film or the like not shown. The signal electrode layers 3A and the ground electrode layers 3C of all the divided element portions 31 are led out from the ultrasonic probe PB1 via the conductive patterns W1 and W2 of the wiring board 2, respectively. The connection between the signal electrode layer 3A and the ground electrode layer 3C of each divided element portion 31 and the wiring board 2 is not limited to the above-mentioned method, and can be performed by various methods, for example, using solder, conductive resin, sputtered film, etc.

[0042] By applying a voltage via the wiring board 2 to the signal electrode layer 3A and the ground electrode layer 3C of each of the four divided element portions 31 divided in the elevation direction in a plurality of piezoelectric elements 3 arranged in the azimuth direction, the depth of the transmission focus of the ultrasonic beam can be electronically varied in the elevation direction as well, making it possible to generate high-definition ultrasonic images both at shallow and deep locations.

[0043] In the ultrasonic probe PB1 of embodiment 1, a plurality of piezoelectric elements 3 arranged in the azimuth direction are each divided into four divided element portions 31 in the elevation direction, and the signal electrode layers 3A of the divided element portions 31E at the two ends arranged in the elevation direction are electrically connected to each other by the conductive pattern W1 of the wiring board 2, and the signal electrode layers 3A of the two divided element portions 31C located in the center in the elevation direction are electrically connected to each other by the conductive pattern W2 of the wiring board 2. Therefore, while suppressing the number of signal lines for driving, the depth of the transmission focus of the ultrasonic beam can be electronically varied in the elevation direction, and high-definition ultrasonic images can be generated both at shallow and deep areas.

[0044] In the ultrasonic probe PB1 of the first embodiment, the divided element portion 31 has a size of an elevation length Ly1=1 mm, an azimuth length Lx1=0.07 mm, and a Z-direction thickness Lz1=0.1 mm, but this is not limited to this and the size can be, for example, about an elevation length Ly1=0.5 to 2 mm, an azimuth length Lx1=0.05 to 0.2 mm, and a Z-direction thickness Lz1=0.05 to 0.2 mm.

[0045] Embodiment 2 In the ultrasonic probe PB1 of embodiment 1 shown in FIG. 2, the dividing grooves G2 that separate the four divided element portions 31 divided in the elevation direction extend from the boundary between the piezoelectric element 3 and the conductive layer 4 to the inside of the wiring board 2, but this is not limited to this.

[0046] 5 shows the configuration of an ultrasonic probe PB2 according to embodiment 2. In this ultrasonic probe PB2, divided element portions 31 adjacent to each other in the elevation direction are separated from each other by a separating groove G3, and the separating groove G3 extends from the boundary between the piezoelectric element 3 and the conductive layer 4 to the boundary between the piezoelectric element 3 and the wiring board 2. In other words, the separating groove G3 has a groove depth equal to the thickness of the piezoelectric element 3 in the Z direction, and does not extend into the wiring board 2. The dividing groove G3 is filled with a filler 6.

[0047] Although not shown, in the ultrasonic probe PB2 of embodiment 2, the dividing grooves that divide adjacent piezoelectric elements 3 in the azimuth direction also have a groove depth equal to the thickness of the piezoelectric elements 3 in the Z direction, similar to the dividing groove G3, and do not extend into the interior of the wiring board 2. The ultrasonic probe PB2 of the second embodiment is configured in the ultrasonic probe PB1 of the first embodiment such that adjacent divided element portions 31 in the elevation direction are separated by a separating groove G3 instead of the separating groove G2, and adjacent piezoelectric elements 3 in the azimuth direction are separated from each other by a separating groove having a groove depth equal to the thickness of the piezoelectric element 3 in the Z direction instead of the separating groove G1, and the other configurations are the same as those of the ultrasonic probe PB1 of the first embodiment.

[0048] In the ultrasonic probe PB2 having such a configuration, like the ultrasonic probe PB1 of the first embodiment, the number of signal lines for driving is reduced, and the depth of the transmission focus of the ultrasonic beam in the elevation direction is electronically variable, thereby making it possible to generate high-definition ultrasonic images in both shallow and deep areas.

[0049] Third embodiment 6 shows the configuration of an ultrasonic probe PB3 according to embodiment 3. In this ultrasonic probe PB3, the dividing groove G4 that divides the divided element portions 31 adjacent to each other in the elevation direction extends to the +Z direction end of the acoustic matching layer 5. That is, the dividing groove G4 extends from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring board 2.

[0050] Furthermore, the acoustic matching layer 5 is disposed directly on the ground electrode layer 3C of each divided element portion 31, and a conductive layer 4 is formed on the +Z direction end of the acoustic matching layer 5, extending along the XY plane so as to cover the entire ultrasonic probe PB3. The ground electrode layer 3C of each divided element portion 31 is electrically connected to the conductive layer 4 via, for example, a resin film with a conductive film (not shown). The dividing groove G4 is filled with a filler 6.

[0051] Although not shown, in the ultrasonic probe PB3 of embodiment 3, the dividing groove that divides adjacent piezoelectric elements 3 in the azimuth direction also extends from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring substrate 2, similar to the dividing groove G4. The ultrasonic probe PB3 of embodiment 3 is configured such that the piezoelectric element 3 and the acoustic matching layer 5 of the ultrasonic probe PB1 of embodiment 1 are divided in the azimuth direction by a dividing groove extending from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring board 2, and are also divided in the elevation direction by a dividing groove G4, and a conductive layer 4 is formed on the +Z direction end of the acoustic matching layer 5, and the other configurations are similar to those of the ultrasonic probe PB1 of embodiment 1.

[0052] In the ultrasonic probe PB3 having such a configuration, like the ultrasonic probe PB1 of the first embodiment and the ultrasonic probe PB2 of the second embodiment, the number of signal lines for driving is reduced, and the depth of the transmission focus of the ultrasonic beam in the elevation direction is electronically variable, thereby making it possible to generate high-definition ultrasonic images in both shallow and deep areas.

[0053] 6 divides the first acoustic matching layer 5A, the second acoustic matching layer 5B, and the third acoustic matching layer 5C of the acoustic matching layer 5, but the invention is not limited thereto and may be configured to extend from the inside of the wiring board 2 and the divided element portion 31 to partway in the Z direction of the acoustic matching layer 5. For example, the dividing groove G4 may divide the first acoustic matching layer 5A and the second acoustic matching layer 5B of the acoustic matching layer 5 but not divide the third acoustic matching layer 5C, or the dividing groove G4 may divide the first acoustic matching layer 5A of the acoustic matching layer 5 but not divide the second acoustic matching layer 5B and the third acoustic matching layer 5C.

[0054] Fourth embodiment 7 shows the configuration of an ultrasonic probe PB4 according to embodiment 4. In this ultrasonic probe PB4, of the four divided element portions 31 divided in the elevation direction, the two divided element portions 31C located in the center are not completely separated from each other, but a part of the piezoelectric body portion 3B and the signal electrode layer 3A are connected to each other. A dividing groove G5 is formed between the two divided element portions 31C, extending in the -Z direction from the boundary portion between the piezoelectric element 3 and the conductive layer 4 toward the wiring board 2.

[0055] The piezoelectric body 3B of the divided element portion 31C has a first surface M1 in contact with the signal electrode layer 3A and a second surface M2 in contact with the ground electrode layer 3C, and the dividing groove G5 extends from the second surface M2 toward the first surface M1 in the piezoelectric body 3B and has a depth dimension D2 that is greater than 90% of the thickness D1 of the piezoelectric body 3B in the Z direction. That is, the two divided element portions 31C are connected to each other via the signal electrode layer 3A that spans these two divided element portions 31C and the connection portion 3Br that is located on the +Z direction side of the signal electrode layer 3A and remains as a part of the piezoelectric body 3B. The signal electrode layer 3A that is common to the two divided element portions 31C is connected to the conductive pattern W2 of the wiring board 2.

[0056] The ultrasonic probe PB4 of the fourth embodiment is configured such that, of the four divided element portions 31 in the ultrasonic probe PB1 of the first embodiment, the two divided element portions 31C located in the center are adjacent to each other in the elevation direction via a dividing groove G5 and are connected to each other via the signal electrode layer 3A and a connecting portion 3Br, and the other configurations are the same as those of the ultrasonic probe PB1 of the first embodiment.

[0057] Two divided element portions 31C adjacent in the elevation direction via a dividing groove G5 having a depth dimension D2 that is greater than 90% of the thickness D1 in the Z direction of the piezoelectric body portion 3B are connected to each other via the signal electrode layer 3A and the connection portion 3Br, but are separated from each other in terms of mechanical vibration and act similarly to two divided element portions 31C that are completely separated as in the ultrasonic probe PB1 of embodiment 1. Here, "separated from each other in terms of mechanical vibration" means that when a voltage is applied to one of the two divided element portions 31C or vibration occurs due to reception of an ultrasonic echo, the vibration has almost no effect on the other divided element portion 31C and reaches an unmeasurable level.

[0058] Therefore, also in the ultrasonic probe PB4 of embodiment 4, if the aspect ratios R of the four divided element portions 31 divided in the elevation direction are approximately equal, and the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratios R is within a range of 10% of the average value Rav of the aspect ratios R of the four divided element portions 31, the frequency band shapes of the sensitivity in the four divided element portions 31 will be approximately equal.

[0059] Therefore, in the ultrasonic probe PB4 of embodiment 4, like the ultrasonic probes PB1 to PB3 of embodiments 1 to 3, the number of signal lines for driving is reduced, and the depth of the transmission focus of the ultrasonic beam in the elevation direction can be electronically varied, thereby making it possible to generate high-definition ultrasonic images in both shallow and deep areas. Furthermore, in the ultrasonic probe PB4 of embodiment 4, the signal electrode layers 3A of the two divided element portions 31C located in the center in the elevation direction are connected to each other, and this signal electrode layer 3A is connected to the conductive pattern W2 of the wiring board 2. Therefore, the wiring board 2 only needs to have one conductive pattern W2 for the two divided element portions 31C, and the configuration of the wiring board 2 can be simplified.

[0060] Fifth embodiment In the ultrasonic probe PB1 of embodiment 1 shown in FIG. 2, the multiple piezoelectric elements 3 arranged in an array along the azimuth direction are each divided into four divided element portions 31 in the elevation direction, but this is not limited to this.

[0061] 8 shows the configuration of an ultrasonic probe PB5 according to embodiment 5. In this ultrasonic probe PB5, a plurality of piezoelectric elements 3 arranged in the azimuth direction are each divided in the elevation direction into five divided element portions 31. Each of the five divided element portions 31 is divided in the elevation direction via dividing grooves G6, and the dividing grooves G6 are filled with a filler 6.

[0062] The five divided element portions 31 have approximately the same aspect ratio R, which is expressed by the ratio of the thickness Lz2 in the Z direction to the length Ly2 in the elevation direction of each divided element portion 31. Specifically, the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratios R of the five divided element portions 31 divided in the elevation direction is set to be within a range of 10% of the average value Rav of the aspect ratios R of the five divided element portions 31.

[0063] Of the five divided element portions 31 divided in the elevation direction, the signal electrode layers 3A of the two end divided element portions 31E located at both ends in the elevation direction are both connected to one conductive pattern W1 of the wiring board 2, and these two divided element portions 31E are configured to be driven simultaneously by a common driving voltage via the conductive pattern W1. Furthermore, of the five divided element portions 31 divided in the elevation direction, the signal electrode layers 3A of the three central divided element portions 31C are all connected to the conductive pattern W2 of the wiring board 2, and these three divided element portions 31C are configured to be driven simultaneously by a common driving voltage via the conductive pattern W2.

[0064] The ultrasonic probe PB5 of embodiment 5 has a similar configuration to the ultrasonic probe PB1 of embodiment 1, except that the piezoelectric element 3 is divided into five divided element portions 31 in the elevation direction via dividing grooves G6, and the signal electrode layers 3A of the three centrally located divided element portions 31C are commonly connected to the conductive pattern W2 of the wiring board 2.

[0065] In the ultrasonic probe PB5 having such a configuration, like the ultrasonic probes PB1 to PB4 of the first to fourth embodiments, the number of signal lines for driving is reduced, and the depth of the transmission focus of the ultrasonic beam in the elevation direction can be electronically varied, thereby making it possible to generate high-definition ultrasonic images in both shallow and deep areas.

[0066] In addition, for the ultrasonic probes PB2 to PB4 of the second to fourth embodiments, the piezoelectric element 3 can also be divided into five divided element portions 31 in the elevation direction as in the fifth embodiment. Also, each of the plurality of piezoelectric elements 3 arranged in the azimuth direction can be divided into six or more and ten or less divided element portions 31 in the elevation direction.

[0067] In the above-mentioned first to fifth embodiments, the four or five divided element portions 31 divided in the elevation direction are classified into two groups consisting of two divided element portions 31E arranged at both ends in the elevation direction and two or three divided element portions 31C located in the center in the elevation direction, but the present invention is not limited to this. For example, the divided element portions 31 divided in the elevation direction may be classified into three or more groups according to their arrangement positions in the elevation direction, and the signal electrode layers 3A of the divided element portions 31 in the group including at least two divided element portions 31 located in the center in the elevation direction and adjacent to each other may be electrically connected to each other, and each group may be connected to a different conductive pattern of the wiring board 2. [Explanation of symbols]

[0068] 1 backing material, 2 wiring board, 3 piezoelectric element, 3A signal electrode layer, 3B piezoelectric body portion, 3Br connection portion, 3C ground electrode layer, 4 conductive layer, 5 acoustic matching layer, 5A first acoustic matching layer, 5B second acoustic matching layer, 5C third acoustic matching layer, 6 filler, PB1 to PB5 ultrasonic probes, G1, G2, G3, G4, G6 dividing grooves, 31, 31E, 31C divided element portions, Ly1, Ly2 length, Lz1, Lz2, D1 thickness, C1, C2 curves, W1, W2 conductive patterns, P1 arrangement pitch, F1 groove width, G5 dividing groove, M1 first surface, M2 second surface, D2 depth dimension.

Claims

1. An ultrasonic probe in which a plurality of piezoelectric elements are arranged in an array along an azimuth direction on a backing material, each of the plurality of piezoelectric elements is formed of a laminate in which a signal electrode layer, a piezoelectric body portion, and a ground electrode layer are laminated in this order on a surface of the backing material; Each of the piezoelectric elements is divided into a plurality of divided element portions, the number of which is 4 or more and 10 or less, in an elevation direction; a difference between a maximum value and a minimum value of an aspect ratio represented by a ratio of a thickness to a length in the elevation direction in each of the plurality of divided element portions is within a range of 10% of an average value of the aspect ratios in the plurality of divided element portions; an arrangement pitch of the plurality of divided element portions in the elevation direction is greater than a wavelength of an ultrasonic wave determined by a center frequency of the ultrasonic probe; an ultrasonic probe, wherein the signal electrode layers of at least two of the plurality of divided element portions that are arranged in the center in the elevation direction and adjacent to each other are electrically connected to each other.

2. a wiring board having a conductive pattern is disposed between the plurality of piezoelectric elements and the backing material; 2. The ultrasonic probe according to claim 1, wherein the signal electrode layers and the ground electrode layers of the plurality of piezoelectric elements are each led out via the conductive pattern of the wiring board.

3. 3. The ultrasonic probe according to claim 2, wherein each of the plurality of divided element portions is divided in the elevation direction by a dividing groove extending from the ground electrode layer to the signal electrode layer.

4. The ultrasonic probe according to claim 3 , wherein the dividing groove extends to an inside of the wiring substrate.

5. 4. The ultrasonic probe according to claim 3, further comprising an acoustic matching layer laminated on the ground electrode layers of the plurality of piezoelectric elements.

6. The ultrasonic probe according to claim 5 , wherein the dividing groove extends to an inside of the acoustic matching layer.

7. The ultrasonic probe according to claim 3 , wherein the dividing groove has a groove width in the elevation direction of 10 μm or more and 30 μm or less.

8. 8. The ultrasonic probe according to claim 7, wherein the dividing groove is filled with a filler.

9. 3. The ultrasonic probe according to claim 2, wherein the at least two divided element portions are mechanically separated in the elevation direction while a part of the piezoelectric portion and the signal electrode layer are connected to each other.

10. the piezoelectric portion has a first surface in contact with the signal electrode layer and a second surface in contact with the ground electrode layer, The ultrasonic probe according to claim 9 , wherein the piezoelectric portions of the at least two divided element portions are adjacent to each other in the elevation direction via a dividing groove extending from the second surface toward the first surface.

11. The ultrasonic probe according to claim 10, wherein the dividing groove has a depth dimension that is greater than 90% of the thickness of the piezoelectric body portion.

12. The ultrasonic probe according to claim 10 , wherein the dividing groove has a groove width in the elevation direction of 10 μm or more and 30 μm or less.

13. The ultrasonic probe according to claim 12, wherein the dividing grooves are filled with a filler.

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