Ultrasonic probe

Abstract

Provided is an ultrasonic probe capable of generating a high-definition ultrasonic image while suppressing the number of signal lines for driving. Each of a plurality of piezoelectric elements (3) arranged in the azimuth direction is divided into four or more and ten or less divided element portions (31) in the elevation direction. The difference between the maximum value and the minimum value of the aspect ratio represented by the ratio of the thickness (Lz1) of each divided element portion to the length (Ly1) in the elevation direction is within the range of 10% with respect to the average value of the aspect ratios in the plurality of divided element portions. The array pitch (P1) in the elevation direction of the plurality of divided element portions is larger than the wavelength of the ultrasonic wave determined by the center frequency of the ultrasonic probe, and the signal electrode layers (3A) of at least two adjacent divided element portions (31C) disposed in the center in the elevation direction among the plurality of divided element portions are electrically connected to each other.

Description

Technical Field

[0001] The present invention relates to an ultrasonic probe, and in particular to an ultrasonic probe in which a plurality of piezoelectric elements arranged in an azimuth direction are respectively divided into a plurality of divided element parts in an elevation direction. Background Art

[0002] Ultrasonic diagnostic devices using ultrasonic images have been put into practical use in the medical field. Generally, such ultrasonic diagnostic devices transmit ultrasonic beams from an ultrasonic probe toward a subject, receive ultrasonic echoes from the subject with the ultrasonic probe, and electrically process the received signals to generate ultrasonic images.

[0003] As an ultrasonic probe, for example, a one-dimensional array probe can be used in which a plurality of piezoelectric elements are arranged in a straight line in the azimuth direction. By adjusting the delay amount of the plurality of piezoelectric elements to drive them, the depth of the transmission focus of the ultrasonic beam can be electronically variable on the tomographic plane in the azimuth direction. However, in the elevation direction, a fixed focus is often set by an acoustic lens disposed at the front of the probe.

[0004] On the other hand, as disclosed in Patent Documents 1 and 2, if a two-dimensional array probe in which a plurality of piezoelectric elements are arranged two-dimensionally is used, the depth of the transmission focus of the ultrasonic beam can be adjusted individually on a cross-sectional plane along any direction.

[0005] However, in a 2D array probe, the number of piezoelectric elements increases significantly, and as a result, multiple signal lines are required to drive the probe, which increases the thickness and weight of the cable connecting the ultrasonic probe and the device body, and increases the burden on the user who operates the ultrasonic diagnostic device due to rigidification. In addition, the manufacturing cost of the ultrasonic diagnostic device increases, and the processing circuit becomes complicated.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 07-131895

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 03-243099

[0008] 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.

[0009] In this 1.5-dimensional array probe, by dividing the piezoelectric element in the elevation direction, the depth of the transmission focus of the ultrasonic beam can be made electronically variable even in the elevation direction, thereby generating high-definition ultrasonic images regardless of the depth and reducing the number of signal lines used to drive the probe.

[0010] In this type of 1.5-dimensional array probe, usually, since the division width of the piezoelectric element in the elevation direction is determined based on the sensitivity of the probe, the beam shape (F value), etc., the thickness-to-width ratio of each element part after division, which is expressed by the ratio of the thickness to the length in the elevation direction, sometimes differs by several times.

[0011] If a difference in aspect ratio occurs in a plurality of element portions arranged in the elevation direction, the sensitivity band shapes in the element portions will differ due to the difference in sound speed, and a high-definition ultrasonic image may not be generated. Summary of the invention

[0012] The present invention has been made to solve such conventional problems, and an object of the present invention is to provide an ultrasonic probe capable of generating high-definition ultrasonic images while suppressing the number of signal lines for driving.

[0013] The above-mentioned object can be achieved according to the following structure.

[0014] [1] An ultrasonic probe, which is a plurality of piezoelectric elements arranged in an array along an azimuth direction on a backing material, wherein:

[0015] Each of the plurality of piezoelectric elements is composed of a stacked body 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.

[0016] Each piezoelectric element is divided into a plurality of divided element parts of not less than 4 and not more than 10 in the elevation direction.

[0017] The difference between the maximum value and the minimum value of the aspect ratio represented by the ratio of the thickness to the length in the elevation direction of each of the plurality of segmentation element portions is within 10% of the average value of the aspect ratios of the plurality of segmentation element portions,

[0018] The arrangement pitch of the plurality of segmented element portions in the elevation direction is larger than the wavelength of the ultrasonic wave determined by the center frequency of the ultrasonic probe.

[0019] Among the plurality of divided element portions, the signal electrode layers of at least two divided element portions that are arranged at the center in the elevation direction and are adjacent to each other are electrically connected to each other.

[0020] [2] The ultrasonic probe according to [1], wherein:

[0021] A wiring substrate having a conductive pattern is arranged between the plurality of piezoelectric elements and the backing material.

[0022] The signal electrode layers and the ground electrode layers of the plurality of piezoelectric elements are respectively led out through the conductive patterns of the wiring substrate.

[0023] [3] The ultrasonic probe according to [2], wherein:

[0024] A plurality of divisional element portions are respectively divided (split) in a vertical direction via split grooves extending from the ground electrode layer to the signal electrode layer.

[0025] [4] The ultrasonic probe according to [3], wherein the partition groove extends into the interior of the wiring substrate.

[0026] [5] The ultrasonic probe according to [3] or [4], wherein an acoustic matching layer is stacked on the ground electrode layer of the plurality of piezoelectric elements.

[0027] [6] The ultrasonic probe according to [5], wherein the partition groove extends into the interior of the acoustic matching layer.

[0028] [7] The ultrasonic probe according to any one of [3] to [6], wherein the partition groove has a groove width of 10 μm or more and 30 μm or less in the elevation direction.

[0029] [8] The ultrasonic probe according to [7], wherein:

[0030] The partition groove is filled with a filler.

[0031] [9] The ultrasonic probe according to [2], wherein:

[0032] In at least two divided element portions, a part of the piezoelectric body and the signal electrode layer are connected to each other, and mechanical vibration is blocked in the elevation direction.

[0033]

[10] The ultrasonic probe according to [9], wherein:

[0034] The piezoelectric body has a first surface in contact with the signal electrode layer and a second surface in contact with the ground electrode layer.

[0035] The piezoelectric body portions of at least two segmented element parts are adjacent to each other in the elevation direction via a partition groove extending from the second surface toward the first surface.

[0036]

[11] The ultrasonic probe according to

[10] , wherein:

[0037] The partition groove has a depth dimension greater than 90% of the thickness of the piezoelectric body.

[0038]

[12] The ultrasonic probe according to

[10] or

[11] , wherein:

[0039] The partition groove has a groove width of 10 μm or more and 30 μm or less in the elevation direction.

[0040]

[13] An ultrasonic probe according to

[12] , wherein:

[0041] The partition groove is filled with a filler.

[0042] Effects of the Invention

[0043] According to the invention, a plurality of piezoelectric elements are respectively composed of a stacked body 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 more than four divided element portions in an elevation direction. The difference between the maximum and minimum values ​​of the thickness-to-width ratio represented by the ratio of the thickness of each of the plurality of divided element portions to the length in the elevation direction is within a range of 10% relative to an average value of the thickness-to-width ratio in the plurality of divided element portions. The arrangement pitch of the plurality of divided element portions in the elevation direction is larger than the wavelength of the ultrasonic wave determined by the center frequency of the ultrasonic probe. Among the plurality of divided element portions, the signal electrode layers of at least two divided element portions which are arranged in the center in the elevation direction and adjacent to each other are electrically connected to each other, thereby being able to generate a high-definition ultrasonic image while suppressing the number of signal lines used for driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a partial perspective view showing the ultrasonic probe according to the first embodiment of the present invention.

[0045] Figure 2 It is a cross-sectional view along the elevation direction of the ultrasonic probe according to the first embodiment of the present invention.

[0046] Figure 3 This is a graph showing simulation results for calculating the frequency band of sensitivity when the aspect ratio of the piezoelectric element is changed.

[0047] Figure 4 This is a flowchart showing the method for manufacturing the ultrasonic probe according to the first embodiment of the present invention.

[0048] Figure 5 It is a cross-sectional view along the elevation direction of the ultrasonic probe according to the second embodiment of the present invention.

[0049] Figure 6 It is a cross-sectional view along the elevation direction of the ultrasonic probe according to the third embodiment of the present invention.

[0050] Figure 7 It is a cross-sectional view along the elevation direction of the ultrasonic probe according to the fourth embodiment of the present invention.

[0051] Figure 8 It is a cross-sectional view along the elevation direction of the ultrasonic probe according to the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0053] The description of the constituent elements described below is based on typical embodiments of the present invention, but the present invention is not limited to these embodiments.

[0054] In addition, in this specification, the numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0055] In this specification, “same” and “identical” include a range of error generally allowed in the technical field.

[0056] Implementation Method 1

[0057] Figure 1 2 shows the structure of an ultrasonic probe PB1 according to Embodiment 1 of the present invention. The ultrasonic probe PB1 has a structure in which a backing material 1, a wiring substrate 2, a plurality of piezoelectric elements 3, a conductive layer 4, and an acoustic matching layer 5 are sequentially stacked in a stacking direction.

[0058] The backing material 1 is a flat plate-shaped member extending along the entire length direction and width direction of the ultrasonic probe PB1 , and the wiring board 2 is on the surface of the backing material 1 and extends over the entire surface of the backing material 1 .

[0059] The plurality of piezoelectric elements 3 disposed on the wiring substrate 2 are arranged in an array in the azimuth direction, and partition grooves G1 extending in the elevation direction and the stacking direction are formed between adjacent piezoelectric elements 3, and the partition grooves G1 are filled with fillers 6. Furthermore, the plurality of piezoelectric elements 3 arranged in the azimuth direction are divided into four divided element parts 31 in the elevation direction, and partition grooves G2 extending in the azimuth direction and the stacking direction are formed between adjacent divided element parts 31, and the partition grooves G2 are filled with fillers 6.

[0060] Here, for convenience, the azimuthal direction in which the flat backing material 1 extends along the XY plane and in which the plurality of 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.

[0061] A conductive layer 4 extending along the XY plane is arranged on the plurality of piezoelectric elements 3 , and an acoustic matching layer 5 extending along the XY plane is arranged on the conductive layer 4 .

[0062] 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 sequentially stacked on the conductive layer 4 .

[0063] In addition, the partition grooves G1 and G2 in the plurality of piezoelectric elements 3 all extend in the Z direction from the boundary portion between the piezoelectric element 3 and the conductive layer 4 to the inside of the wiring substrate 2 .

[0064] The backing material 1 supports the plurality of piezoelectric elements 3 via the wiring substrate 2 and absorbs ultrasonic waves radiated from the plurality of piezoelectric elements 3 in the rear of the ultrasonic probe PB1 , that is, in the −Z direction, and is made of a rubber material such as ferrite rubber.

[0065] The wiring substrate 2 arranged on the backing material 1 is composed of, for example, an FPC (Flexible Printed Circuit), and although not shown, has a plurality of conductive patterns corresponding to all divided element portions 31 divided into four in the elevation direction from each of the plurality of piezoelectric elements 3 .

[0066] The conductive layer 4 disposed on the plurality of piezoelectric elements 3 forms a common ground potential layer for all the segmented element portions 31 .

[0067] The acoustic matching layer 5 is a layer for matching the acoustic impedance of the piezoelectric element 3 and the subject so that the ultrasonic wave can be easily incident into the subject. The acoustic matching layer 5 can be formed of a material having an acoustic impedance smaller than the acoustic impedance of the piezoelectric element 3 and larger than the acoustic impedance of the subject. For example, by making the acoustic impedance of the second acoustic matching layer 5B smaller than the acoustic impedance of the first acoustic matching layer 5A and making the acoustic impedance of the third acoustic matching layer 5C smaller than the acoustic impedance of the second acoustic matching layer 5B, a layer structure in which the acoustic impedance gradually decreases from the piezoelectric element 3 toward the subject is formed.

[0068] The acoustic matching layer 5 is not limited to the one 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.

[0069] The filler 6 filled in the partition grooves G1 and G2 is used to fix the positions and postures of the piezoelectric elements 3 adjacent to each other in the X direction and the segmented element portions 31 adjacent to each other in the Y direction. For example, epoxy resin, silicone rubber, etc. can be used as the filler 6.

[0070] like Figure 2 As shown, the piezoelectric element 3 is formed of a stacked body in which a signal electrode layer 3A, a piezoelectric body portion 3B, and a ground electrode layer 3C are stacked in this order on a wiring substrate 2 .

[0071] The piezoelectric body 3B is formed of a known piezoelectric material, expands and contracts by applying a voltage and emits ultrasonic waves, and expands and contracts by receiving so-called ultrasonic echoes from the outside and generates electrical signals. As piezoelectric materials, for example, piezoelectric ceramics represented by PZT (Lead Zirconate Titanate), polymer piezoelectric elements represented by PVDF (Poly Vinylidene Di Fluoride), and piezoelectric single crystals represented by PMN-PT (Lead Magnesium Niobate-Lead Titanate: Lead Magnesium Niobate-Lead Titanate Solid Solution) can be cited.

[0072] The signal electrode layer 3A is used to apply a voltage to the piezoelectric body 3B and to extract an electric signal generated when the piezoelectric body 3B expands and contracts by receiving a so-called ultrasonic echo.

[0073] The ground electrode layer 3C is used to set the reference potential of the piezoelectric body 3B to a predetermined ground potential.

[0074] The signal electrode layer 3A and the ground electrode layer 3C are respectively formed of a metal thin film formed on the surface on the −Z direction side and the surface on the +Z direction side of the piezoelectric body 3B using, for example, a sputtering method.

[0075] The four segmented element portions 31 segmented in the elevation direction have substantially 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 segmented 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 segmented element portions 31 segmented in the elevation direction is set to be within 10% of the average value Rav of the aspect ratio R of the four segmented element portions 31.

[0076] Figure 3 , which shows the simulation results for calculating the frequency band of the sensitivity of the piezoelectric element when the aspect ratio R of the piezoelectric element is changed. Figure 3 In FIG. 1 , curve C1 represents the frequency band shape of the piezoelectric element with an aspect ratio of R=0.05, and curve C2 represents the frequency band shape of the piezoelectric element with an aspect ratio of R=0.025.

[0077] like Figure 3 As shown in FIG. 1 , if the piezoelectric element has a different aspect ratio R, the sound velocity in the piezoelectric element will be different, so that the band shape of the sensitivity will be different. Therefore, if the aspect ratio R of the four divided element parts 31 divided in the elevation direction is different by more than a predetermined degree, it may be impossible to generate a high-definition ultrasonic image in the elevation direction.

[0078] However, in the ultrasonic probe PB1 involved in embodiment 1, the difference dR between the maximum value Rmax and the minimum value Rmin of the thickness-to-width ratio R of the four divided element parts 31 divided along the elevation direction is set to be within 10% of the average value Rav of the thickness-to-width ratio R of the four divided element parts 31, so that the frequency band shape of the sensitivity in the four divided element parts 31 is roughly the same, and a high-definition ultrasonic image along the elevation direction can be generated.

[0079] In order to make the band shapes of the sensitivities in the four segmentation element portions 31 more uniform and further improve the resolution of the ultrasonic image in the elevation direction, the difference dR between the maximum value Rmax and the minimum value Rmin of the aspect ratio R of the four segmentation element portions 31 is preferably set to be within, for example, 5% of the average value Rav of the aspect ratio R of the four segmentation element portions 31. By designing the ultrasonic probe PB1 so that the four segmentation element portions 31 have the same aspect ratio R, and manufacturing the ultrasonic probe PB1 while suppressing the manufacturing tolerance 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 to be within 5% of the average value Rav.

[0080] And, if Figure 2 As shown, in the split element part 31 divided into four parts in the elevation direction, the signal electrode layer 3A of the split element part 31E arranged at the two ends in the elevation direction is commonly connected to a conductive pattern W1 of the wiring substrate 2, and these two split element parts 31E are constructed in a manner so as to be driven simultaneously by a common driving voltage separated by the conductive pattern W1.

[0081] Moreover, among the four divided element parts 31 divided along the elevation direction, the signal electrode layer 3A of the two divided element parts 31C located in the center is commonly connected to the conductive pattern W2 which is different from the conductive pattern W1 of the wiring substrate 2, and these two divided element parts 31C are constructed in a manner that they are driven simultaneously by a common driving voltage separated by the conductive pattern W2.

[0082] By adjusting the delay amount of the split element portions 31E at the two ends and driving the two center split element portions 31C simultaneously, the depth of the transmission focus of the ultrasonic beam can be electronically varied on the tomographic plane along the elevation direction.

[0083] As described above, in the ultrasonic probe PB1 according to the first embodiment, the depth of the transmission focus of the ultrasonic beam in the elevation direction is electronically variable, but the ultrasonic beam is not steered in the elevation direction.

[0084] Here, it is known that when the ultrasonic beam is deflected at an angle θ, in order to suppress the generation of the so-called diffraction mask, the wavelength of the ultrasonic wave emitted from the ultrasonic probe PB1 needs to be set to λ, and the arrangement pitch P of the piezoelectric elements arranged in an array needs to be set to P<λ / (1+|sinθ|).

[0085] That is, the arrangement pitch P of the piezoelectric elements needs to be set smaller than the wavelength of the ultrasonic wave. For example, when the ultrasonic wave is deflected at an angle of 45 degrees, P<0.6λ.

[0086] Typically, 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 the azimuth direction and the arrangement pitch of the piezoelectric elements in the elevation direction both need to be smaller than the wavelength of the ultrasonic wave emitted from the probe.

[0087] In the ultrasonic probe PB1 according to the first embodiment, in order to achieve ultrasonic beam steering while suppressing the generation of grating cover in the tomographic plane along the azimuth direction, it is desirable that the arrangement pitch of the piezoelectric elements 3 in the azimuth direction be set to a value smaller than the wavelength of the ultrasonic wave.

[0088] However, in the ultrasonic probe PB1 according to the first embodiment, since the ultrasonic beam is not deflected in the elevation direction, it is not necessary to suppress the generation of the grating cover. Therefore, the arrangement pitch P1 of the four segmentation element portions 31 in the elevation direction is set to a value larger than the wavelength determined by the center frequency of the ultrasonic wave emitted from the ultrasonic probe PB1.

[0089] Thus, for example, the ultrasonic probe PB1 can be manufactured more easily than a two-dimensional array type probe in terms of division of the four divided element portions 31 in the elevation direction and alignment of the divided element portions 31 with the conductive patterns W1 and W2 of the wiring board 2 .

[0090] Furthermore, the partition groove G2 that divides the adjacent division element portions 31 has a groove width F1 of 10 μm to 30 μm, preferably 20 μm or less, in the elevation direction.

[0091] By reducing the groove width F1 of the partition groove G2 , when the total length of the ultrasonic probe PB1 in the elevation direction is made constant, it is possible to ensure the division element portion 31 that is long in the elevation direction, thereby improving the sensitivity of the ultrasonic probe PB1 .

[0092] The segmentation element portion 31 in the ultrasonic probe PB1 according to the first embodiment is formed to have a length Ly1 = 1 mm in the elevation direction, a length Lx1 = 0.07 mm in the azimuth direction, and a thickness Lz1 = 0.1 mm in the Z direction, for example.

[0093] Next, use Figure 4 The method for manufacturing the ultrasonic probe PB1 according to the first embodiment will be described using the flowchart of FIG.

[0094] First, in step S1, wiring substrate 2 is disposed on the surface of backing material 1. Wiring substrate 2 is bonded to backing material 1 by, for example, an adhesive or the like.

[0095] Next, in step S2, a stacked body is formed in which the signal electrode layer 3A, the piezoelectric body portion 3B, and the ground electrode layer 3C are sequentially stacked on the wiring substrate 2. The signal electrode layer 3A, the piezoelectric body portion 3B, and the ground electrode layer 3C are bonded by, for example, an adhesive.

[0096] In step S3 , the laminate is cut to form a plurality of partition grooves G1 extending in each of the Y direction and the Z direction, thereby forming a plurality of piezoelectric elements 3 arranged in the X direction.

[0097] In the next step S4 , each piezoelectric element 3 is cut to form a plurality of partition grooves G2 extending in 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.

[0098] In addition, both the partition grooves G1 and G2 extend in the Z direction from the ground electrode layer 3C of the piezoelectric element 3 to the inside of the wiring substrate 2 .

[0099] Then, in step S5 , the partitioning grooves G1 arranged between the plurality of piezoelectric elements 3 and the partitioning grooves G2 arranged between the plurality of segmented element portions 31 are filled with the filler 6 .

[0100] Next, in step S6, after forming the conductive layer 4 on the laminate, in step S7, the 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 segmented element portions 31 arranged in the Y direction.

[0101] Conductive layer 4 is formed, for example, by attaching metal foil to a laminate, and acoustic matching layer 5 is formed, for example, by sequentially bonding first acoustic matching layer 5A, second acoustic matching layer 5B, and third acoustic matching layer 5C at a temperature of 80° C. to 100° C.

[0102] So, like Figure 1 As shown, an ultrasonic probe PB1 is manufactured in which a plurality of piezoelectric elements 3 are arranged in the azimuth direction, that is, the X direction, and each piezoelectric element 3 is divided into a plurality of divided element portions 31 in the elevation direction, that is, the Y direction.

[0103] In addition, a plurality of conductive patterns W1 and W2 corresponding to the plurality of piezoelectric elements 3 and the plurality of segmented element portions 31 are pre-formed on the wiring substrate 2, and a laminate is formed on the wiring substrate 2 in step S2, and the laminate is cut in steps S3 and S4, whereby the plurality of segmented element portions 31 segmented from the piezoelectric elements 3 are respectively arranged on the corresponding conductive patterns W1 and W2. Thus, the signal electrode layer 3A of each segmented element portion 31 is bonded to and electrically connected to the corresponding conductive patterns W1 and W2 of the wiring substrate 2.

[0104] In this way, among the four split element parts 31 divided along the elevation direction, the signal electrode layer 3A of the split element part 31E arranged at the two ends at the two ends in the elevation direction is connected together with the conductive pattern W1 of the wiring substrate 2, and the signal electrode layer 3A of the two split element parts 31C arranged in the center in the elevation direction is connected together with the conductive pattern W2 of the wiring substrate 2.

[0105] The ground electrode layers 3C of all the segmented element portions 31 in the ultrasonic probe PB1 are bonded to and electrically connected to the conductive layer 4 , and the conductive layer 4 is connected to the ground pattern of the wiring board 2 via a resin film with a conductive film (not shown).

[0106] Furthermore, 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 substrate 2 , respectively.

[0107] The connection between the signal electrode layer 3A and the ground electrode layer 3C of each divided element portion 31 and the wiring substrate 2 is not limited to the above method, and can be performed by various methods such as soldering, conductive resin, sputtering, etc.

[0108] By applying voltages separately to the signal electrode layer 3A and the ground electrode layer 3C which are divided into four divided element parts 31 in the elevation direction among the multiple piezoelectric elements 3 arranged along the azimuth direction, through the wiring substrate 2, the depth of the transmission focus of the ultrasonic beam can be made electronically variable even in the elevation direction, thereby generating high-definition ultrasonic images regardless of whether they are shallow or deep.

[0109] In the ultrasonic probe PB1 involved in embodiment 1, the multiple piezoelectric elements 3 arranged along the azimuth direction are respectively divided into four divided element parts 31 in the elevation direction, and the signal electrode layers 3A of the divided element parts 31E arranged at the two ends at both ends in the elevation direction are electrically connected to each other through the conductive pattern W1 of the wiring substrate 2, and the signal electrode layers 3A of the two divided element parts 31C located in the center in the elevation direction are electrically connected to each other through the conductive pattern W2 of the wiring substrate 2. Therefore, while the number of signal lines used for driving can be suppressed, the depth of the transmission focus of the ultrasonic beam can be set to be electronically variable even in the elevation direction, and high-definition ultrasonic images can be generated regardless of whether they are shallow or deep.

[0110] In addition, in the ultrasonic probe PB1 of embodiment 1, the split element portion 31 has a length in the elevation direction Ly1=1 mm, a length in the azimuth direction Lx1=0.07 mm, and a thickness in the Z direction Lz1=0.1 mm, but is not limited to this. For example, it can also be set to a length in the elevation direction Ly1=0.5~2 mm, a length in the azimuth direction Lx1=0.05~0.2 mm, and a thickness in the Z direction Lz1=0.05~0.2 mm.

[0111] Implementation Method 2

[0112] exist Figure 2 In the ultrasonic probe PB1 of the first embodiment shown, the partition groove G2 that separates the four segmented element portions 31 divided in the elevation direction from each other extends from the boundary between the piezoelectric element 3 and the conductive layer 4 to the inside of the wiring substrate 2, but the present invention is not limited to this.

[0113] Figure 5 2 shows the structure of the ultrasonic probe PB2 according to Embodiment 2. In the ultrasonic probe PB2, the segmented element portions 31 adjacent in the elevation direction are separated from each other by the partition groove G3, and the partition groove G3 extends from the boundary portion between the piezoelectric element 3 and the conductive layer 4 to the boundary portion between the piezoelectric element 3 and the wiring substrate 2. That is, the partition groove G3 has a groove depth equal to the thickness of the piezoelectric element 3 in the Z direction, but does not extend to the inside of the wiring substrate 2.

[0114] The partition groove G3 is filled with a filler 6 .

[0115] Although not shown in the figure, in the ultrasonic probe PB2 involved in embodiment 2, the partition groove that divides the piezoelectric elements 3 adjacent to each other in the azimuth direction also has a groove depth equal to the thickness of the piezoelectric element 3 in the Z direction, just like the partition groove G3, and does not extend into the interior of the wiring substrate 2.

[0116] The ultrasonic probe PB2 involved in embodiment 2 is the same as the ultrasonic probe PB1 of embodiment 1 in that the partition groove G3 is used instead of the partition groove G2 to partition the split element parts 31 adjacent in the elevation direction, and the piezoelectric elements 3 adjacent in the azimuth direction are partitioned from each other by a partition groove having a groove depth equal to the thickness of the piezoelectric element 3 in the Z direction instead of the partition groove G1. The other structures are the same as those of the ultrasonic probe PB1 of embodiment 1.

[0117] Even in the ultrasonic probe PB2 of this structure, as with the ultrasonic probe PB1 of embodiment 1, it is possible to suppress the number of signal lines used for driving, and at the same time, make the depth of the transmission focus of the ultrasonic beam electronically variable even in the elevation direction, thereby generating high-definition ultrasonic images regardless of whether they are shallow or deep.

[0118] Implementation 3

[0119] Figure 6 2 shows the structure of the ultrasonic probe PB3 according to the third embodiment. In the ultrasonic probe PB3, the partition groove G4 that divides the partition element portions 31 adjacent in the elevation direction from each other extends to the +Z direction end of the acoustic matching layer 5. That is, the partition groove G4 extends from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring substrate 2.

[0120] The acoustic matching layer 5 is directly disposed on the ground electrode layer 3C of each division element portion 31 , and a conductive layer 4 extending along the XY plane is formed on the +Z direction end of the acoustic matching layer 5 so as to cover the entire ultrasonic probe PB3 .

[0121] 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).

[0122] The partition groove G4 is filled with a filler 6 .

[0123] Although not shown, in the ultrasonic probe PB3 according to the third embodiment, the partitioning grooves that partition the piezoelectric elements 3 adjacent to each other in the azimuth direction also extend from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring substrate 2 similarly to the partitioning grooves G4 .

[0124] The ultrasonic probe PB3 involved in the third embodiment is the same as the ultrasonic probe PB1 of the first embodiment in that the piezoelectric element 3 and the acoustic matching layer 5 are divided in the azimuth direction by a partition groove extending from the +Z direction end of the acoustic matching layer 5 to the inside of the wiring substrate 2, and are also divided in the elevation direction by a partition groove G4, and a conductive layer 4 is formed on the +Z direction end of the acoustic matching layer 5. The other structures are the same as those of the ultrasonic probe PB1 of the first embodiment.

[0125] Even in the ultrasonic probe PB3 having such a structure, as in the ultrasonic probe PB1 of embodiment 1 and the ultrasonic probe PB2 of embodiment 2, it is possible to suppress the number of signal lines used for driving and to make the depth of the transmission focus of the ultrasonic beam in the elevation direction electronically variable, thereby generating high-definition ultrasonic images in both shallow and deep parts.

[0126] in addition, Figure 6 The partition groove G4 shown in the figure partitions all of 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 present invention is not limited thereto, and may be configured to extend from the inside of the wiring substrate 2 and the dividing element portion 31 to the middle of the acoustic matching layer 5 in the Z direction. For example, the partition groove G4 may be configured to partition the first acoustic matching layer 5A and the second acoustic matching layer 5B of the acoustic matching layer 5 without partitioning the third acoustic matching layer 5C, or the partition groove G4 may be configured to partition the first acoustic matching layer 5A of the acoustic matching layer 5 without partitioning the second acoustic matching layer 5B and the third acoustic matching layer 5C.

[0127] Implementation 4

[0128] Figure 7 2 shows the structure of the ultrasonic probe PB4 according to the fourth embodiment. In the ultrasonic probe PB4, among the four segmented element portions 31 segmented in the elevation direction, the two segmented element portions 31C located in the center are not completely segmented from each other, but a part of the piezoelectric body portion 3B and the signal electrode layer 3A are connected to each other. Between the two segmented element portions 31C, a partition groove G5 extending in the -Z direction from the boundary portion between the piezoelectric element 3 and the conductive layer 4 toward the wiring substrate 2 is formed.

[0129] The piezoelectric body 3B of the split element part 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 partition groove G5 extends from the second surface M2 toward the first surface M1 in the piezoelectric body 3B and has a depth dimension D2 greater than 90% of the thickness D1 of the piezoelectric body 3B in the Z direction. That is, the two split element parts 31C are connected to each other through the signal electrode layer 3A spanning the two split element parts 31C and the connecting part 3Br located on the +Z direction side of the signal electrode layer 3A and remaining as a part of the piezoelectric body 3B. In addition, the signal electrode layer 3A common to the two split element parts 31C is connected to the conductive pattern W2 of the wiring substrate 2.

[0130] The ultrasonic probe PB4 involved in embodiment 4 is the same as the ultrasonic probe PB1 of embodiment 1 in that the two central split element parts 31C of the four split element parts 31 are adjacent in the elevation direction via the partition groove G5, and are connected to each other via the signal electrode layer 3A and the connecting part 3Br. The other structures are the same as those of the ultrasonic probe PB1 of embodiment 1.

[0131] The two segmented element portions 31C adjacent to each other in the elevation direction through the segmentation groove G5 having a depth dimension D2 greater than 90% of the thickness D1 in the Z direction of the piezoelectric body 3B are connected to each other through the signal electrode layer 3A and the connection portion 3Br, but the state in which the mechanical vibrations are isolated from each other functions in the same manner as the two segmented element portions 31C that are completely separated as in the ultrasonic probe PB1 of Embodiment 1. Here, "the mechanical vibrations are isolated from each other" means that when a voltage is applied to one of the two segmented element portions 31C or when vibrations are generated by receiving ultrasonic echoes, the influence of the vibration on the other segmented element portion 31C is almost non-existent and is at a level that cannot be measured.

[0132] Therefore, in the ultrasonic probe PB4 of embodiment 4, even if the thickness-to-width ratios R of the four divided element parts 31 divided along the elevation direction are almost equal, if the difference dR between the maximum value Rmax and the minimum value Rmin of the thickness-to-width ratio R is within the range of 10% relative to the average value Rav of the thickness-to-width ratio R of the four divided element parts 31, the frequency band shapes of the sensitivities in the four divided element parts 31 are also almost the same.

[0133] Therefore, in the ultrasonic probe PB4 of embodiment 4, as with the ultrasonic probes PB1 to PB3 of embodiments 1 to 3, it is possible to suppress the number of signal lines used for driving and, at the same time, make the depth of the transmission focus of the ultrasonic beam electronically variable even in the elevation direction, thereby generating high-definition ultrasonic images regardless of whether they are shallow or deep.

[0134] Furthermore, in the ultrasonic probe PB4 of embodiment 4, the signal electrode layers 3A of the two split element parts 31C located in the center in the elevation direction are connected to each other, and the signal electrode layer 3A is connected to the conductive pattern W2 of the wiring substrate 2. Therefore, the wiring substrate 2 only needs to have one conductive pattern W2 relative to the two split element parts 31C, thereby simplifying the structure of the wiring substrate 2.

[0135] Implementation method 5

[0136] exist Figure 2 In the ultrasonic probe PB1 of the first embodiment shown, the plurality of piezoelectric elements 3 arranged in an array in the azimuth direction are each divided into four divided element portions 31 in the elevation direction, but the present invention is not limited thereto.

[0137] Figure 8 , the structure of the ultrasonic probe PB5 according to Embodiment 5 is shown. In the ultrasonic probe PB5, a plurality of piezoelectric elements 3 arranged in the azimuth direction are respectively divided into five divided element parts 31 in the elevation direction. The five divided element parts 31 are respectively divided in the elevation direction by partition grooves G6, and the partition grooves G6 are filled with fillers 6.

[0138] The five divided element portions 31 have substantially the same aspect ratio R, which is represented 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 ratio R of the five divided element portions 31 divided in the elevation direction is set to be within 10% of the average value Rav of the aspect ratio R of the five divided element portions 31.

[0139] Among the five split element parts 31 divided along the elevation direction, the signal electrode layer 3A of the split element part 31E arranged at the two ends in the elevation direction is commonly connected to a conductive pattern W1 of the wiring substrate 2, and these two split element parts 31E are constructed in a manner so as to be driven simultaneously by a common driving voltage separated by the conductive pattern W1.

[0140] Moreover, among the five divided element parts 31 divided in the elevation direction, the signal electrode layers 3A of the three divided element parts 31C located in the center are commonly connected to the conductive pattern W2 of the wiring substrate 2, and these three divided element parts 31C are configured in a manner to be simultaneously driven by a common driving voltage through the conductive pattern W2.

[0141] The piezoelectric element 3 of the ultrasonic probe PB5 involved in embodiment 5 is divided into five divided element parts 31 in the elevation direction separated by the partition groove G6, and the signal electrode layer 3A of the three divided element parts 31C located in the center is connected to the conductive pattern W2 of the wiring substrate 2. Other than this, it has the same structure as the ultrasonic probe PB1 of embodiment 1.

[0142] Even in the ultrasonic probe PB5 of this structure, as with the ultrasonic probes PB1 to PB4 of embodiments 1 to 4, it is possible to suppress the number of signal lines used for driving, and at the same time, make the depth of the transmission focus of the ultrasonic beam electronically variable even in the elevation direction, thereby generating high-definition ultrasonic images regardless of whether they are shallow or deep.

[0143] In addition, in the ultrasonic probes PB2 to PB4 of the second to fourth embodiments, the piezoelectric element 3 can be divided into five divided element portions 31 in the elevation direction as in the fifth embodiment.

[0144] Furthermore, the plurality of piezoelectric elements 3 arranged in the azimuth direction may be divided into six or more and ten or less divided element portions 31 in the elevation direction.

[0145] In the above-mentioned first to fifth embodiments, the four or five split element portions 31 split in the elevation direction are classified into two groups consisting of two split element portions 31E arranged at both ends in the elevation direction and two or three split element portions 31C arranged at the center position in the elevation direction, but the present invention is not limited to this. For example, it is also possible to configure as follows: the plurality of split element portions 31 split in the elevation direction are classified into three or more groups according to the arrangement positions in the elevation direction, the signal electrode layers 3A of the respective split element portions 31 in the group including at least two split element portions 31 located in the center and adjacent to each other in the elevation direction are electrically connected to each other, and the respective groups are connected to different conductive patterns of the wiring substrate 2.

[0146] Explanation of symbols

[0147] 1-backing material, 2-wiring substrate, 3-piezoelectric element, 3A-signal electrode layer, 3B-piezoelectric body part, 3Br-connecting part, 3C-ground electrode layer, 4-conductive layer, 5-acoustic matching layer, 5A-1st acoustic matching layer, 5B-2nd acoustic matching layer, 5C-3rd acoustic matching layer, 6-filler, PB1~PB5-ultrasonic probe, G1, G2, G3, G4, G6-partitioning groove, 31, 31E, 31C-dividing element part, Ly1, Ly2-length, Lz1, Lz2, D1-thickness, C1, C2-curve, W1, W2-conductive pattern, P1-arrangement spacing, F1-groove width, G5-partitioning groove, M1-1st surface, M2-2nd surface, D2-depth dimension.

Claims

1. An ultrasonic probe, which is a plurality of piezoelectric elements arranged in an array along the azimuth direction on a backing material, wherein: The plurality of piezoelectric elements are each composed of a stacked body in which a signal electrode layer, a piezoelectric body portion, and a ground electrode layer are sequentially stacked on the surface of the backing material. Each of the piezoelectric elements is divided into a plurality of divided element parts of not less than 4 and not more than 10 in the elevation direction, The difference between the maximum value and the minimum value of the thickness-to-width ratio of each of the plurality of dividing element parts is within 10% of the average value of the thickness-to-width ratio of the plurality of dividing element parts, the thickness-to-width ratio being represented by the ratio of the thickness to the length in the elevation direction, The arrangement pitch of the plurality of segmentation element portions in the elevation direction is larger than the wavelength of the ultrasonic wave determined by the center frequency of the ultrasonic probe. The signal electrode layers of at least two of the plurality of segmentation element portions that are disposed at the center in the elevation direction and are adjacent to each other are electrically connected to each other.

2. The ultrasonic probe according to claim 1, wherein: A wiring substrate having a conductive pattern is arranged between the plurality of piezoelectric elements and the backing material. The signal electrode layers and the ground electrode layers of the plurality of piezoelectric elements are respectively led out through the conductive pattern of the wiring substrate.

3. The ultrasonic probe according to claim 2, wherein: The plurality of dividing element portions are respectively partitioned in the elevation direction via partition grooves extending from the ground electrode layer to the signal electrode layer.

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

5. The ultrasonic probe according to claim 3, wherein: An acoustic matching layer is stacked on the ground electrode layer of the plurality of piezoelectric elements.

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

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

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

9. The ultrasonic probe according to claim 2, wherein: Parts of the piezoelectric body and the signal electrode layer of the at least two divided element portions are connected to each other, and mechanical vibration of the at least two divided element portions in the elevation direction is blocked.

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

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

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

13. The ultrasonic probe according to claim 12, wherein: The partition groove is filled with a filler.

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