Ultrasonic probe

Abstract

The present invention addresses the problem of providing an ultrasonic probe in which the intensity of a grating beam is reduced without reducing the pitch of vibrating elements in a vibrating element array and without reducing the transmission frequency of ultrasonic waves. The ultrasonic probe has a vibrating element array (10) comprising a plurality of vibrating elements (12) arranged in the array direction. The vibrating element (12) is virtually divided into a first virtual portion (12a) and a second virtual portion (12b) by a straight line (22) that passes through the center of gravity (20) of the vibrating element (12) and extends in the array direction. The vibration element (12) has a shape such that a first virtual center of gravity (24a), which is the center of gravity of the first virtual portion (12a), and a second virtual center of gravity (24b), which is the center of gravity of the second virtual portion (12b), are located at mutually different positions in the array direction.

Description

Technical Field

[0001] This specification discloses an improvement to an ultrasonic probe. Background Technology

[0002] An ultrasonic diagnostic apparatus is known that can form an ultrasonic tomographic image representing a cross-section in an ultrasonic scanning plane or perform various measurements based on the reflected waves from the subject when ultrasonic waves are transmitted to it. The ultrasonic diagnostic apparatus includes an ultrasonic probe that contacts the subject and transmits and receives ultrasonic waves from the subject. The ultrasonic probe has multiple vibrating elements, and ultrasonic waves are transmitted from the multiple vibrating elements toward the subject by supplying a transmission signal from the main body of the ultrasonic diagnostic apparatus to each of the multiple vibrating elements. Furthermore, the multiple vibrating elements receive the reflected waves from the subject and convert them into received signals, which are then transmitted to the main body of the apparatus.

[0003] Previously, various improvements to ultrasonic probes have been proposed, particularly improvements to the arrangement of multiple vibrating elements. For example, Patent Document 1 discloses an ultrasonic probe in which the vibrating elements are tilted along the array direction in order to obtain two-dimensional or three-dimensional images in real time through the ultrasonic probe with vibrating elements arranged in a one-dimensional direction (array direction). Furthermore, Patent Document 2 discloses a cylindrical ultrasonic transducer, which is a cylindrical ultrasonic transducer with the transducer tilted relative to the circumferential direction.

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-62396

[0006] Patent Document 2: Japanese Patent Application Publication No. 11-64492

[0007] However, virtual images sometimes appear in ultrasound tomographic images generated by ultrasound diagnostic devices. These virtual images are also known as artifacts. One cause of artifacts is the presence of a grating beam. (Reference) Figures 45-48 The grating beam is explained.

[0008] Figure 45 This is a plan view of the vibrating element array (PEA) of a conventional ultrasonic probe. Figure 46 This is a side view of a conventional vibrating element array (PEA). Furthermore, in this specification, a plan view refers to a view taken from the depth direction, and a side view refers to a view taken from the elevation direction. Also, in this specification, the arrangement direction of the multiple vibrating elements (PEs) is referred to as the array direction, the direction parallel to (on the same plane) the vibrating element surface and perpendicular to the array direction is referred to as the elevation direction, and the direction perpendicular to both the array direction and the elevation direction is referred to as the depth direction.

[0009] like Figure 45 As shown, it is assumed here that the conventional vibrating element PE has a roughly rectangular shape extending along the elevation direction. Ultrasonic waves are output from each vibrating element PE by supplying a transmitting signal to each vibrating element PE. Figure 46 In this diagram, the wavefront (WF) of the ultrasonic waves output from each vibrating element (PE) is represented by an arc centered on each PE. By synthesizing the wavefronts (WF) from each PE, a synthesized wavefront (CWFm) is formed, giving the ultrasonic waves the properties of a beam. The direction indicated by the arrow Dm perpendicular to the synthesized wavefront (CWFm) is the transmission direction of the ultrasonic beam. The intended output (the targeted) ultrasonic beam is called the master beam. Figure 46 As shown, if ultrasonic waves are simultaneously output from each vibrating element PE, the direction of the main beam becomes parallel to the depth direction. However, by controlling the timing of the ultrasonic wave output from each vibrating element PE, the direction of the main beam can be controlled.

[0010] Here, sometimes an ultrasonic beam (called a grating beam) is formed in a direction different from the main beam. For example, as Figure 46 As shown, consider the case where ultrasonic waves are simultaneously output from each vibrating element PE, and the direction of the main beam is set to be parallel to the depth direction. When ultrasonic waves are repeatedly output from each vibrating element PE according to the transmission frequency, the grating beam is formed by combining the wavefront WF output from a certain vibrating element PE and the wavefront WF output from the vibrating element PE adjacent to that vibrating element PE, which is offset by one cycle from that wavefront WF.

[0011] Figure 47 This diagram illustrates the principle of grating beam generation. First, a wavefront WFa is output from the vibrating element PEa. At this time, wavefronts are also output from other vibrating elements PE, including PEb and PEc, but... Figure 47 The wavefront diagram is omitted. After one cycle (1 / f[s] after the transmission frequency f), the wavefront WFb is output from the vibrating element PEb. At this time, the wavefront output from the vibrating element PE (other than PEb) is also omitted. Furthermore, after one cycle, the wavefront WFc is output from the vibrating element PEc. At this time, the wavefront output from the vibrating element PE (other than PEc) is also omitted.

[0012] In this way, a synthetic wavefront CWFg is formed by synthesizing wavefronts WFa, WFb, and WFc, which also possesses the properties of a beam. This is a grating beam, and the direction of transmission of the grating beam is indicated by the arrow Dg perpendicular to the synthetic wavefront CWFG.

[0013] Figure 48 This is a diagram used to illustrate the conditions for generating a grating beam. In Figure 48In the diagram, the spacing between the vibrating elements PE in the vibrating element array PEA (referred to as the vibrating element spacing in this specification) is represented by P, and the angle of the main beam relative to the depth direction (the direction of the arrow Dm) is represented by θm. When multiple vibrating elements PE are arranged on a plane, the generation condition of the grating beam is represented by the following Equation 1.

[0014] P>λ / (1+sinθm)…Equation 1

[0015] In Equation 1, λ is the wavelength of the ultrasonic wave output from each vibrating element PE, and is the reciprocal of the ultrasonic wave transmission frequency.

[0016] According to Equation 1, the lower the transmission frequency of the ultrasound (the higher the wavelength), the more difficult it is to generate a grating beam. However, from the perspective of high-quality ultrasound tomography, it is sometimes not suitable to reduce the transmission frequency of the ultrasound. Furthermore, according to Equation 1, the lower the spacing between the vibrating elements, the more difficult it is to generate a grating beam. However, there are also limitations on reducing the spacing between the vibrating elements due to cost or manufacturing issues. Summary of the Invention

[0017] The purpose of the ultrasonic probe disclosed in this specification is to reduce the intensity of the grating beam without reducing the spacing between the vibrating elements of the vibrating element array or the transmission frequency of the ultrasonic waves.

[0018] The ultrasonic probe disclosed in this specification comprises an array of vibrating elements consisting of a plurality of vibrating elements arranged along an array direction. The ultrasonic probe is characterized in that, when the vibrating elements are virtually divided into a first virtual part and a second virtual part by a straight line passing through the center of gravity of the vibrating elements and extending along the array direction, each of the vibrating elements has a shape such that the first virtual center of gravity, which is the center of gravity of the first virtual part, and the second virtual center of gravity, which is the center of gravity of the second virtual part, are located at different positions in the array direction. Due to the shape, the grating beam output from the first virtual part and the grating beam output from the second virtual part cancel each other out by phase shift, thereby reducing the intensity of the grating beam output from each of the vibrating elements.

[0019] Preferably, in a planar view viewed from the depth direction, the shape of the vibrating element is a polygon with more than one pentagon, or at least one side of the vibrating element is a curve.

[0020] Preferably, in a planar view viewed from the depth direction, the shapes of the first virtual portion and the second virtual portion are in an asymmetrical relationship centered on the center of gravity of the vibrating element.

[0021] Preferably, the distance between the first virtual center of gravity and the second virtual center of gravity in the array direction, i.e., the distance between virtual centers of gravity, is less than the spacing between the vibration elements in the vibration element array.

[0022] Preferably, when the plurality of vibrating elements are arranged on a plane, the distance between the virtual centers of gravity is half the distance between the vibrating elements.

[0023] Preferably, when the plurality of vibrating elements are arranged on a curved surface, the distance between the virtual centers of gravity is half of the virtual spacing P' between the vibrating elements.

[0024] Wherein, the virtual spacing P' is composed of

[0025] P'=Psinθg / sin(θg-β)

[0026] β=(N / 4)*α

[0027] In this context, P represents the spacing between the vibrating elements, θg represents the beam angle of the grating beam, N represents the number of aperture vibrating elements, and α represents the angular spacing between the vibrating elements.

[0028] Invention Effects

[0029] According to the ultrasonic probe disclosed in this specification, the intensity of the grating beam can be reduced without reducing the spacing between the vibrating elements of the vibrating element array or the transmission frequency of the ultrasonic wave. Attached Figure Description

[0030] Figure 1 This is Figure 1, used to illustrate the cancellation conditions of the grating beam.

[0031] Figure 2 This is Figure 2, used to illustrate the cancellation conditions of the grating beam.

[0032] Figure 3 This is a side view of the vibrating element array of the ultrasonic probe according to the first embodiment.

[0033] Figure 4 This is a plan view of the vibrating element array of the ultrasonic probe according to the first embodiment.

[0034] Figure 5 It is an enlarged planar view of the vibrating element.

[0035] Figure 6 It means in Figure 4 A diagram showing the grating beam generated in a conventional linear array at the elevation position shown in Figure A.

[0036] Figure 7 It means in Figure 4A diagram of the grating beam generated in the vibrating element array according to the first embodiment at the position in the elevation direction shown in A.

[0037] Figure 8 It means in Figure 4 The diagram shown in B illustrates the grating beam generated in a conventional linear array at the elevation position.

[0038] Figure 9 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the first embodiment at the position in the elevation direction shown in B.

[0039] Figure 10 It means in Figure 4 The diagram shows the grating beam generated in a conventional linear array at the elevation position shown in C.

[0040] Figure 11 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the first embodiment at the position shown in C in the elevation direction.

[0041] Figure 12 It means in Figure 4 The diagram shows the position of the grating beam generated in a conventional linear array at the elevation direction shown in D.

[0042] Figure 13 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the first embodiment at the position shown in D in the elevation direction.

[0043] Figure 14 It means in Figure 4 The diagram shows the position of the grating beam generated in a conventional linear array at the elevation direction shown in E.

[0044] Figure 15 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the first embodiment at the elevation direction position shown in E.

[0045] Figure 16 It is a diagram representing the grating beam of a conventional linear array at a specified depth in two-dimensional space, representing the array direction and elevation direction.

[0046] Figure 17 It is a diagram showing the grating beam of the vibrating element array according to the first embodiment at a specified depth in a two-dimensional space of the array direction and elevation direction at a specified depth.

[0047] Figure 18 It is a diagram representing the grating beams generated in a conventional linear array as a whole in the elevation direction.

[0048] Figure 19 This is a diagram showing the grating beam generated in the vibrating element array according to the first embodiment as a whole in the elevation direction.

[0049] Figure 20 It is a graph showing the relationship between signal strength and beam angle at a specified depth in the first embodiment.

[0050] Figure 21 It is a graph showing the relationship between the grating level and the distance between the virtual centroids at the beam angle where the intensity of the grating beam reaches its peak in the first embodiment.

[0051] Figure 22 This is Figure 1, which illustrates the appropriate upper limit for the distance between virtual centroids.

[0052] Figure 23 The second figure is used to illustrate the appropriate upper limit of the distance between virtual centers of gravity.

[0053] Figure 24 This is a diagram showing a deformation example of a vibrating element.

[0054] Figure 25 This is a side view of the vibrating element array of the ultrasonic probe according to the second embodiment.

[0055] Figure 26 It means in Figure 4 A diagram of the grating beam generated in a conventional curved surface array at the elevation position shown in Figure A.

[0056] Figure 27 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the second embodiment at the elevation direction position shown in A.

[0057] Figure 28 It means in Figure 4 The diagram shown in B illustrates the grating beam generated in a conventional curved surface array at the elevation position.

[0058] Figure 29 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the second embodiment at the elevation direction position shown in B.

[0059] Figure 30 It means in Figure 4The diagram shows the grating beam generated in a conventional curved surface array at the elevation position shown in C.

[0060] Figure 31 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the second embodiment at the position shown in C in the elevation direction.

[0061] Figure 32 It means in Figure 4 The diagram shows the grating beam generated in a conventional curved surface array at the elevation position shown in D.

[0062] Figure 33 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the second embodiment at the position shown in D in the elevation direction.

[0063] Figure 34 It means in Figure 4 The diagram shows the grating beam generated in a conventional curved surface array at the elevation position shown in E.

[0064] Figure 35 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array according to the second embodiment at the elevation direction position shown in E.

[0065] Figure 36 It is a diagram representing the grating beam at a specified depth of a conventional curved surface array in two-dimensional space, representing the array direction and elevation direction.

[0066] Figure 37 It is a diagram showing the grating beam at a specified depth in a two-dimensional space in the array direction and elevation direction at a specified depth, relating to the vibrating element array of the second embodiment.

[0067] Figure 38 It is a diagram representing the grating beams generated in a conventional curved surface array as a whole in the elevation direction.

[0068] Figure 39 This is a diagram showing the grating beam generated in the vibrating element array according to the second embodiment as a whole in the elevation direction.

[0069] Figure 40 It is a graph showing the relationship between signal strength and beam angle at a specified depth in the second embodiment.

[0070] Figure 41It is a graph showing the relationship between the grating beam level and the distance between the virtual centroids at the beam angle where the intensity of the grating beam reaches its peak in the second embodiment.

[0071] Figure 42 This is Figure 1, used to illustrate the calculation method for virtual spacing.

[0072] Figure 43 This is Figure 2, which illustrates the calculation method for virtual spacing.

[0073] Figure 44 It is a graph showing the relationship between the width of the main beam and the distance between the virtual centroids.

[0074] Figure 45 This is a plan view of the vibrating element array installed in a conventional ultrasonic probe.

[0075] Figure 46 This is a side view of a conventional array of vibrating elements.

[0076] Figure 47 This is a diagram illustrating the principle of grating beam generation.

[0077] Figure 48 This is a diagram used to illustrate the conditions for generating a grating beam.

[0078] Symbol Explanation

[0079] 10, 10-2 - Vibration element array, 12, 12-2, 12x - Vibration element, 12a - First virtual part, 12b - Second virtual part, 20 - Center of gravity, 24a - First virtual center of gravity, 24b - Second virtual center of gravity, P - Spacing between vibration elements, ΔG - Distance between virtual centers of gravity, P' - Virtual spacing. Detailed Implementation

[0080] <Cancellation Conditions for Grating Beams>

[0081] Before describing the first embodiment, the cancellation conditions of the grating beam will be explained. Figure 1 and Figure 2 This is a diagram used to illustrate the cancellation conditions of the grating beam. Figure 1 It is a plan view of the vibration element array PEA, which has an approximately rectangular shape in which each vibration element PE extends along the elevation direction.

[0082] Figure 1 The spacing between the vibrating elements in the array PEA shown is set to p0. Here, p0 is set to match the wavelength λ of the ultrasonic waves output from each vibrating element PE, satisfying the above-mentioned conditions for generating a grating beam. That is, if ultrasonic waves are output from each vibrating element PE included in the array PEA, a grating beam is generated.

[0083] Here, consider as Figure 2 As shown in the vibrating element array PEA', the spacing between the vibrating elements is set to p0 / 2, that is, half of the spacing between the vibrating elements that satisfies the conditions for generating the grating beam. In the vibrating element array PEA', also... Figure 1 Similarly, multiple vibrating elements PE are arranged in the array direction, but in the vibrating element array PEA', it can be considered that, conceptually, the vibrating elements PE'x with shaded lines are arranged alternately with the blank vibrating elements PE'y.

[0084] In the vibrating element array PEA', if the transmission direction of the grating beam is observed, the grating beam formed by the ultrasonic waves output from vibrating element PE'x and the grating beam formed by the ultrasonic waves output from the vibrating element PE'y adjacent to vibrating element PE'x are out of phase with each other, thus the two grating beams cancel each other out. Therefore, by setting the vibrating element spacing P to half of p0 that satisfies the grating beam generation condition, the intensity of the grating beam can be reduced.

[0085] In the embodiments disclosed in this specification, the intensity of the grating beam is reduced by utilizing the above-described cancellation condition of the grating beam.

[0086] <First Implementation>

[0087] Figure 3 This is a side view of the vibrating element array 10 of the ultrasonic probe according to the first embodiment. Figure 4 This is a plan view of the vibrating element array 10 of the ultrasonic probe according to the first embodiment. The ultrasonic probe is connected to the main body of an ultrasonic diagnostic device for use. The ultrasonic probe has a vibrating element array 10 composed of multiple vibrating elements 12. If a transmission signal as an electrical signal is supplied from the main body of the ultrasonic diagnostic device to each vibrating element 12, ultrasonic waves of a transmission frequency (or wavelength) corresponding to the transmission signal are output from each vibrating element 12. Furthermore, each vibrating element 12 receives the reflected wave of the output ultrasonic wave from the subject and outputs a received signal as an electrical signal to the main body of the ultrasonic diagnostic device. In the main body of the ultrasonic diagnostic device, various processes such as the formation of ultrasonic images (ultrasonic tomographic images or Doppler images) and various measurements are performed based on the received signal.

[0088] like Figure 3 As shown, the vibration element array 10 according to the first embodiment is composed of a plurality of vibration elements 12 arranged on a plane. In this specification, the vibration element array composed of a plurality of vibration elements 12 arranged on a plane is thus referred to as a linear array. That is, the vibration element array 10 according to the first embodiment is a linear array. Furthermore, as... Figure 3 and Figure 4As shown, the spacing between the vibrating elements in the vibrating element array 10 is represented by P.

[0089] Figure 4 The dashed line in the text, for example, represents... Figure 45 The previously shown vibrating element has its extension direction parallel to the elevation direction. For example... Figure 4 As shown, each vibration element 12 included in the vibration element array 10 according to the first embodiment has a shape different from the shape of the conventional vibration element indicated by the dashed line. Hereinafter, reference will be made to... Figure 5 The shape of the vibration element 12 according to the first embodiment will be described in detail.

[0090] Figure 5 This is an enlarged plan view of the vibrating element 12. Here, the vibrating element 12 is virtually (conceptually) divided into two parts by a straight line 22 that passes through the center of gravity 20 of the vibrating element 12 and extends along the array direction. In this specification, Figure 5 In this context, the portion above line 22 (the part with the shaded line) is called the first virtual portion 12a, and the portion below line 22 (the blank portion) is called the second virtual portion 12b. Figure 5 The image shows a first virtual center of gravity 24a, which is the center of gravity of the first virtual part 12a, and a second virtual center of gravity 24b, which is the center of gravity of the second virtual part 12b.

[0091] The vibrating element 12 has a shape in which a first virtual center of gravity 24a and a second virtual center of gravity 24b are located at different positions in the array direction. Figure 5 In this configuration, the first virtual center of gravity 24a is shifted to the left relative to the center of gravity 20 in the array direction, and the second virtual center of gravity 24b is shifted to the right relative to the center of gravity 20 in the array direction. Therefore, the first virtual center of gravity 24a and the second virtual center of gravity 24b are shifted by an amount ΔG in the array direction. In this specification, the distance between the first virtual center of gravity 24a and the second virtual center of gravity 24b in the array direction is referred to as the virtual center of gravity distance ΔG, and the virtual center of gravity distance ΔG is expressed in units of the vibrating element spacing P (e.g., 0.5P).

[0092] As an example of the shapes where the first virtual center of gravity 24a and the second virtual center of gravity 24b are located at different positions in the array direction, the vibrating element 12 can be a shape in a planar view viewed from the depth direction where the shapes of the first virtual portion 12a and the second virtual portion 12b are point-symmetric about the center of gravity 20 of the vibrating element 12. Figure 5In the example, the vibrating element 12 is quadrilateral (especially a parallelogram). When the vibrating element 12 is a parallelogram, the first virtual centroid 24a and the second virtual centroid 24b are located at different positions in the array direction, thus the extension direction of the vibrating element 12 is not parallel to the elevation direction, becoming... Figure 5 The shape extends downwards at an angle relative to the elevation direction.

[0093] The effects of the vibrating element 12 having the shape described above will now be explained. The ultrasonic transceiver wavefront of the vibrating element 12 has a certain area, and ultrasonic waves are actually output from the entire ultrasonic transceiver wavefront. However, for simplicity, regarding the first virtual portion 12a, it is considered that ultrasonic waves are output from the first virtual centroid 24a, and regarding the second virtual portion 12b, it is considered that ultrasonic waves are output from the second virtual centroid 24b. Thus, the first virtual centroid 24a and the second virtual centroid 24b are located (offset) at different positions in the array direction, therefore, as referenced... Figure 1 and Figure 2 As explained, the phase shift between the grating beam formed by the ultrasonic waves output from the first virtual centroid 24a and the grating beam formed by the ultrasonic waves output from the second virtual centroid 24b causes the two grating beams to cancel each other out. This reduces the intensity of the grating beam. In particular, if the distance ΔG between the virtual centroids is set to P / 2, which is half the distance between the vibrating elements, the phases of the grating beam formed by the ultrasonic waves output from the first virtual centroid 24a and the grating beam formed by the ultrasonic waves output from the second virtual centroid 24b are opposite, thus the two grating beams cancel each other out, further reducing the intensity of the grating beam. Therefore, the optimal value of the distance ΔG between the virtual centroids is P / 2.

[0094] The following is for reference. Figures 6 to 20 The verification results of the grating beam intensity when the distance between virtual centroids ΔG is set to P / 2 are explained. The following verification verifies the intensity of the grating beam when the direction of the main beam is set to be parallel to the depth direction.

[0095] Figure 6 It means in Figure 4 The position shown in A in the elevation direction (one end of the vibrating element 12 in the elevation direction) in the conventional linear array ( Figure 4 A diagram of the grating beams generated in the linear array (shown by the dashed lines). Figure 7 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10 at the elevation position shown in Figure A. Figure 8 It means in Figure 4 The diagram shown in B illustrates the grating beam generated in a conventional linear array at the elevation position. Figure 9It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10 at the elevation position shown in B. Figure 10 It means Figure 4 A diagram of the grating beam generated in a conventional linear array at the position in the elevation direction (center of the vibrating element 12 in the elevation direction) shown in C. Figure 11 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10 at the elevation position shown in C. Figure 12 It means in Figure 4 The diagram shows the position of the grating beam generated in a conventional linear array at the elevation direction shown in D. Figure 13 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10 at the elevation position shown in D. Figure 14 It means in Figure 4 A diagram of the grating beam generated in a conventional linear array at the position in the elevation direction (the other end of the vibrating element 12 in the elevation direction) shown in E. Figure 15 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10 at the elevation position shown in E.

[0096] exist Figure 6 In the array, the portion with high signal intensity extending along the depth direction from the center represents the main beam MB, and the portion with slightly higher signal intensity extending radially at a predetermined beam angle from depth 0 at the center of the array represents the grating beam GB. Typically, in... Figure 6 The beam directions of the main beam MB and the grating beam GB are shown, but... Figures 7-15 and Figures 18-19 In this case, the directions of the main beam and the grating beam are also the same.

[0097] If compared separately Figure 6 and Figure 7 , Figure 8 and Figure 9 , Figure 10 and Figure 11 , Figure 12 and Figure 13 and Figure 14 and Figure 15 Therefore, it can be seen that the intensity of the grating beam GB based on the vibration element array 10 according to the first embodiment is reduced. At the center in the elevation direction ( Figure 10 and Figure 11 In this section, the intensity of the grating beam is particularly reduced. On the other hand, at the ends in the elevation direction ( Figure 6 and Figure 7 and Figure 14and Figure 15 In ), on one side of the main beam (in Figure 7 To the left of the main beam, in Figure 15 (To the right of the main beam), the reduction in the grating beam becomes smaller.

[0098] Figure 16 It is a diagram representing the grating beam at a specified depth of a conventional linear array in two-dimensional space with respect to the array direction and elevation direction. Figure 17 This is a diagram representing the grating beam at a predetermined depth of the vibrating element array 10 in two-dimensional space along the array direction and elevation direction. In the vibrating element array 10, the extension direction of each vibrating element 12 extends obliquely relative to the elevation direction, therefore, as... Figure 17 As shown by the straight line L, the direction in which the grating beam is generated will also be tilted.

[0099] Figure 18 It is a diagram representing the grating beams generated in a conventional linear array as a whole in the elevation direction. Figure 19 This is a diagram showing the grating beam generated in the vibrating element array 10 as a whole, in the elevation direction. Figures 6 to 15 In the middle, the grating beams at various positions along the elevation direction were compared, but Figure 18 and Figure 19 This is a graph obtained by averaging the signal strength at locations along various elevation directions. If compared... Figure 18 and Figure 19 Therefore, it can be seen that as a whole in the elevation direction, that is, as a whole in the vibrating element array 10, the grating beam is greatly reduced.

[0100] Figure 20 It is a graph showing the relationship between signal strength and beam angle at a specified depth. Figure 20 In the diagram, the curve represented by the dashed line is a graph of a conventional vibrating element with its extension direction parallel to the elevation direction, while the curve represented by the solid line is a graph of the vibrating element array 10 according to the first embodiment. It can be seen that in the curve represented by the dashed line, the beam angle has a grating peak of ±57 degrees, and the intensity of the grating beam becomes quite large. However, in the curve represented by the solid line, the intensity of the grating beam is greatly reduced.

[0101] Figure 21 This is a graph showing the relationship between the grating level and the distance ΔG between the virtual centroids at the beam angle where the grating beam intensity reaches its peak. Figure 21 In the curve diagram, the distance ΔG between the virtual centroids is 0 (left end of the curve), representing the same shape as the previous vibrating element whose extension direction is parallel to the elevation direction. It can be seen that in... Figure 21Within the range of the virtual centroid distance ΔG shown, the raster level is reduced at least compared to the case where the virtual centroid distance ΔG is 0 (conventional). Furthermore, as mentioned above, the reduction in raster level is greatest when the virtual centroid distance ΔG is P / 2.

[0102] Thus, by shaping the vibrating element 12 such that the first virtual centroid 24a and the second virtual centroid 24b are located at different positions in the array direction, the grating level can be reduced regardless of the distance ΔG between the virtual centroids. However, from a viewpoint other than reducing the intensity of the grating level (especially from the viewpoint of performance degradation of the main beam), there exists an appropriate range (appropriate upper limit) for the distance ΔG between the virtual centroids.

[0103] Figure 22 and Figure 23 This is a diagram illustrating the appropriate upper limit of the distance ΔG between virtual centroids. As described above, in order to control the direction of the main beam, the timing of the ultrasonic wave output from each vibrating element 12 is controlled. That is, a different delay is set for each vibrating element 12, and ultrasonic waves are output from each vibrating element 12 at a timing corresponding to that delay. In order to properly control the direction of the main beam (in other words, to output a main beam with a strong signal intensity at the target beam angle), it is crucial to output ultrasonic waves with an appropriate delay from each position (each sound source) in the array direction. Figure 22 and Figure 23 As shown by the dashed line, in conventional vibrating elements where the extension direction is parallel to the elevation direction, the vibrating elements 12 that serve as the sound source are aligned along the array direction. Thus, by setting different delay amounts for each vibrating element 12, the direction of the main beam can be appropriately controlled.

[0104] If the first virtual center of gravity 24a and the second virtual center of gravity 24b are set to different positions in the array direction, then the first virtual part 12a and the second virtual part 12b are actually a single vibrating element 12. Therefore, the first virtual center of gravity 24a and the second virtual center of gravity 24b are located at different positions in the array direction, but output ultrasonic waves with the same delay (at the same time). In fact, in Figure 22 The ultrasonic waves output from the region indicated by the diagonal line become ultrasonic waves output at a time different from the target delay. This is the main reason for the degradation of the accuracy of the main beam's directional control.

[0105] like Figure 23 As shown, with the increase of the distance ΔG between virtual centroids (in Figure 23In the example shown, the virtual centroid distance ΔG is 1 unit (spacing). The slanted region, i.e., the area where ultrasonic waves are output at timings different from the target delay, becomes larger. In other words, the greater the virtual centroid distance ΔG, the more the accuracy of the main beam's direction control deteriorates. Therefore, there is a trade-off between the main beam's direction control and the reduction in grating level. Thus, it is preferable to determine the virtual centroid distance ΔG within a range that appropriately balances both. Generally, when the virtual centroid distance ΔG is greater than 1 unit, more than half of the vibrating element 12 becomes a slanted region, and the performance of the main beam deteriorates. Therefore, the virtual centroid distance ΔG is preferably smaller than the spacing between the vibrating elements in the vibrating element array 10.

[0106] exist Figure 4 and Figure 5 In the example, the vibrating element 12 is a parallelogram shape, but the shape of the vibrating element 12 can be other shapes as long as the first virtual centroid 24a and the second virtual centroid 24b are located at different positions in the array direction. For example, in a planar view viewed from the depth direction, the shape of the vibrating element 12 can also be a polygon with more than one pentagon. Or, as... Figure 24 As shown in the diagram, at least one side of the vibrating element 12-2, when viewed from above, can be a curve. Furthermore, in... Figure 4 and Figure 5 In the example, in a planar view viewed from the depth direction, the shape of the first virtual part 12a and the shape of the second virtual part 12b of the vibrating element 12 are symmetrical about the center of gravity 20 of the vibrating element 12. However, the vibrating element 12 may also be "asymmetrical" about the center of gravity 20 of the vibrating element 12 in a planar view viewed from the depth direction.

[0107] <Second Implementation>

[0108] Figure 25 This is a side view of the vibrating element array 10-2 of the ultrasonic probe according to the second embodiment. Figure 25 As shown, the vibration element array 10-2 according to the second embodiment is composed of a plurality of vibration elements 12 arranged on a curved surface. In this specification, the vibration element array composed of a plurality of vibration elements 12 arranged on a curved surface is thus referred to as a curved surface array. That is, the vibration element array 10-2 according to the second embodiment is a curved surface array. Furthermore, as... Figure 25As shown, the spacing between the vibrating elements in the vibrating element array 10-2 is also denoted by P. In the curved array, the spacing between the vibrating elements is represented by the radial distance between the centroids of adjacent vibrating elements 12-2. In the curved array, the array direction is curved; therefore, in this specification, the direction perpendicular to the depth direction is described as the transverse direction. Furthermore, in the curved array, the normals of the ultrasonic transceiver wavefronts of each vibrating element 12 point in different directions; therefore, the depth direction and transverse direction of each vibrating element are different.

[0109] In the second embodiment, similarly to the first embodiment, each vibrating element 12, in a planar view viewed from its depth direction, for example as... Figure 4 and Figure 5 As shown, the shape has a first virtual centroid 24a and a second virtual centroid 24b located at different positions in the array direction. Therefore, by the same principle as in the first embodiment, the intensity of the grating beam output from the vibrating element array 10-2 is reduced.

[0110] The following is for reference. Figures 26-40 The verification results of the intensity of the grating beam when the distance between the virtual centroids ΔG is set to P / 2 are explained. In the following verification, the intensity of the grating beam is verified when the direction of the main beam is set to be parallel to the depth direction of one vibrating element 12.

[0111] Figure 26 It means in Figure 4 The position shown in A in the elevation direction (one end of the vibrating element 12 in the elevation direction) in the conventional curved surface array ( Figure 4 A diagram of the grating beams generated in the array shown by the dashed lines. Figure 27 It means in Figure 4 A diagram of the grating beam generated in the vibrating element array 10-2 at the elevation position shown in Figure A. Figure 28 It means in Figure 4 The diagram shown in B illustrates the grating beam generated in a conventional curved surface array at the elevation position. Figure 29 It means in Figure 4 The diagram shows the grating beam generated in the vibrating element array 10-2 at the elevation position shown in B. Figure 30 It means in Figure 4 A diagram of the grating beam generated in a conventional curved surface array at the position in the elevation direction (center of the vibrating element 12 in the elevation direction) shown in C. Figure 31 It means in Figure 4 The diagram shows the grating beam generated in the vibrating element array 10-2 at the elevation position shown in C. Figure 32 It means in Figure 4The diagram shows the grating beam generated in a conventional curved surface array at the elevation position shown in D. Figure 33 It means in Figure 4 The diagram shows the grating beam generated in the vibrating element array 10-2 at the elevation position shown in D. Figure 34 It means in Figure 4 A diagram of the grating beam generated in a conventional curved surface array at the position in the elevation direction (the other end of the vibrating element 12 in the elevation direction) shown in E. Figure 35 It means in Figure 4 The diagram shows the grating beam generated in the vibrating element array 10-2 at the elevation position shown in E.

[0112] exist Figure 26 In the array, the portion with high signal intensity extending along the depth direction from the center of the array direction represents the main beam MB, and the portion with slightly higher signal intensity extending radially from depth 0 at the center of the array direction represents the grating beam GB. Typically, in... Figure 26 The beam directions of the main beam MB and the grating beam GB are shown, but... Figures 27-35 and Figures 38-39 In this case, the directions of the main beam and the grating beam are also the same.

[0113] If compared separately Figure 26 and Figure 27 , Figure 28 and Figure 29 , Figure 30 and Figure 31 , Figure 32 and Figure 33 and Figure 34 and Figure 35 Therefore, it can be seen that the intensity of the grating beam GB is also reduced by the vibration element array 10-2 involved in the second embodiment. Similar to the first embodiment, in the second embodiment, at the center in the elevation direction ( Figure 30 and Figure 31 The intensity of the grating beam is particularly reduced. On the other hand, at the ends in the elevation direction ( Figure 26 and Figure 27 and Figure 34 and Figure 35 In ), on one side of the main beam (in Figure 27 To the left of the main beam, in Figure 35 (To the right of the main beam), the reduction in the grating beam becomes smaller.

[0114] Figure 36 It is a diagram representing a grating beam at a specified depth of a conventional curved surface array in two-dimensional space in both the horizontal and vertical directions. Figure 37This is a diagram showing the grating beam at a predetermined depth of the vibrating element array 10-2 in a two-dimensional space in both the horizontal and vertical directions. Similar to the first embodiment, in the vibrating element array 10-2, the extension direction of each vibrating element 12 is also inclined relative to the vertical direction, therefore... Figure 37 As shown by the straight line L, the direction in which the grating beam is generated will also be tilted.

[0115] Figure 38 It is a diagram representing the grating beams generated in a conventional curved surface array as a whole in the elevation direction. Figure 39 This is a diagram showing the grating beam generated in the vibrating element array 10-2 as a whole, in the elevation direction. Figures 26-35 In the middle, the grating beams at various positions along the elevation direction were compared, but Figure 38 and Figure 39 This is a graph obtained by averaging the signal strength at locations along various elevation directions. If compared... Figure 38 and Figure 39 Therefore, it can be seen that as a whole in the elevation direction, that is, as a whole in the vibrating element array 10-2, the grating beam is greatly reduced.

[0116] Figure 40 It is a graph showing the relationship between signal strength and beam angle at a specified depth. Figure 40 In the diagram, the curve represented by the dashed line is a graph of a conventional vibrating element with its extension direction parallel to the elevation direction, while the curve represented by the solid line is a graph of the vibrating element array 10-2 according to the second embodiment. It can be seen that in the dashed line graph, the beam angle has a grating peak of ±60 degrees, and the intensity of the grating beam becomes quite large; however, in the solid line graph, the grating beam intensity is significantly reduced.

[0117] Figure 41 This is a graph showing the relationship between the grating level and the distance ΔG between the virtual centroids at the beam angle where the grating beam intensity reaches its peak. Figure 41 In the curve diagram, the distance ΔG between the virtual centroids is 0 (left end of the curve), representing the same shape as the previous vibrating element whose extension direction is parallel to the elevation direction. It can be seen that in... Figure 41 Within the range of the virtual centroid distance ΔG shown, the grating level is reduced at least compared to the case where the virtual centroid distance ΔG is 0 (previously).

[0118] In the first embodiment (linear array), the grating level decreases the most when the distance between virtual centroids ΔG is P / 2, but in the second embodiment (curved array), as... Figure 41 As shown, the grating level reduction is greatest when the distance between virtual centroids ΔG is 0.75 spacing instead of P / 2 (0.5 spacing). See below for reference. Figure 42 and Figure 43 The method for determining the optimal virtual centroid distance ΔG in the vibrating element array 10-2, which is a curved surface array, from the viewpoint of reducing the grating level, is explained.

[0119] Figure 42 and Figure 43 This is a diagram illustrating the calculation method for virtual spacing. Figure 42 In the diagram, each vibrating element 12 is simplified by a black circle indicating its center of gravity position. In the following description, as... Figure 42 As shown, the radius of curvature of the surface on which each vibrating element 12 is arranged is set to r (with its center at point O), the angular spacing between the vibrating elements 12 is set to α, and the number of aperture vibrating elements used in the transmission or reception of the vibrating element array 10-2 is set to N. The direction perpendicular to the virtual straight line VL is from the vibrating element 12x (in... Figure 42 When the direction of the main beam is set to the center (directly above), the beam angle of the grating beam relative to the direction of the main beam is set to θg.

[0120] The vibrating element array 10-2 is a curved surface array, with each vibrating element 12 arranged on the curved surface. Therefore, directly calculating the optimal distance ΔG between virtual centers of gravity is difficult. Thus, in this embodiment, as... Figure 43 As shown, the vibration elements 12 arranged on the curved surface are converted into a virtual linear array (virtual linear array), and the spacing between the vibration elements in the virtual linear array (referred to as virtual spacing in this specification) is used to determine the optimal virtual centroid distance ΔG.

[0121] In detail, assuming it passes through a vibrating element 12 (in Figure 42 The virtual straight line VL is the tangent line to the surface on which the vibrating elements 12 are arranged (where 12x is the vibrating element). Then, as shown by arrow AR, the vibrating elements 12 other than 12x are virtually rotated and virtually moved onto the virtual straight line VL, thereby forming a virtual linear array. Here, the rotation angle of each vibrating element 12 can be approximately set as the average angle of the rotation angle of the vibrating elements 12, which is half the diameter of the vibrating element array 10-2. If this average angle is set as β, then β can be expressed by the following equation 2.

[0122] β=(N / 4)*α…Equation 2

[0123] That is, by rotating each vibration element 12 only by an angle β, a virtual linear array in which the vibration elements 12 are virtually arranged on a virtual straight line VL can be formed.

[0124] On the other hand, the conditions for generating grating beams in a linear array can be represented by the following Equation 3.

[0125] P·sinθ=mλ…Equation 3

[0126] In Equation 3, P is the spacing between the vibrating elements, θ is the beam angle of the grating beam, m is an integer, and λ is the wavelength of the ultrasonic wave.

[0127] If we change form 3, we can obtain the following form 4.

[0128] P=mλ / sinθ…Equation 4

[0129] In Equation 4, the grating beam, which serves as the condition for generation, indicates that if the beam angle θ of the grating beam decreases, the spacing P between the vibrating elements increases. As shown in Equation 2, it can be approximated by the following: Since each vibrating element 12 is virtually rotated by an angle β to form a virtual linear array, the grating angle becomes θg-β (reference). Figure 43 Therefore, if mλ is constant, then according to Equation 3,

[0130] P'sin(θ-β)=Psinθg…Equation 5

[0131] Established.

[0132] In Equation 5, P' is the spacing between the vibrating elements in the virtual linear array, i.e., the virtual spacing.

[0133] According to Equation 5, the virtual spacing P' is represented by Equation 6.

[0134] P'=Psinθg / sin(θg-β)...Equation 6

[0135] The virtual spacing P' in the virtual linear array was obtained using Equation 6. Therefore, according to the implementation method, the distance ΔG between the virtual centroids is set to half of the virtual spacing P', thereby further reducing the intensity of the grating beam.

[0136] In Equation 6, when the angle β is sufficiently greater than the angle θg, Equation 6 can be approximately represented by the following Equation 7.

[0137] P'=P / (1-β)…Equation 7

[0138] As a virtual spacing P', the optimal virtual centroid distance ΔG can also be determined using Equation 7.

[0139] Figure 44 This is a graph showing the relationship between the width of the main beam and the distance ΔG between the virtual centroids in the vibrating element array 10-2. The main beam width refers to the angular width of the beam at a signal intensity less than a specified value from the maximum signal intensity of the main beam, using the beam angle at which the main beam reaches its maximum signal intensity as a reference (reference). Figure 40 The smaller the main beam width (BW), the better the performance of the main beam.

[0140] like Figure 44As shown, as the virtual centroid distance ΔG increases, the main beam width BW increases. That is, the performance of the main beam gradually decreases. In other words, the virtual centroid distance ΔG and the main beam width BW are in a trade-off relationship; therefore, it is preferable to consider the balance between the two when determining the virtual centroid distance ΔG. For example, if we compare the case where the virtual centroid distance ΔG is set to 0.5 spacing with the case where it is set to 0.75 spacing, the intensity of the grating beam is further reduced when the virtual centroid distance ΔG is set to 0.75 spacing compared to the case where it is set to 0.5 spacing (see reference). Figure 41 However, this results in a larger main beam width (BW). In this case, one can prioritize reducing the intensity of the grating beam by setting the virtual centroid distance ΔG to 0.75, or prioritize the main beam width (BW) by setting the virtual centroid distance ΔG to 0.5.

[0141] The inspection result display device for vibration elements involved in the present invention has been described above. However, the inspection result display device for vibration elements involved in the present invention is not limited to the above embodiments. Various modifications can be made as long as they do not depart from the spirit of the invention.

Claims

1. An ultrasonic probe comprising an array of vibrating elements consisting of a plurality of vibrating elements arranged along an array direction, characterized in that, When the vibrating element is virtually divided into a first virtual part and a second virtual part by a straight line passing through the center of gravity of the vibrating element and extending along the array direction, each of the vibrating elements has a shape such that the first virtual center of gravity, which is the center of gravity of the first virtual part, and the second virtual center of gravity, which is the center of gravity of the second virtual part, are located at different positions in the array direction. Due to the shape, the grating beam output from the first virtual portion and the grating beam output from the second virtual portion cancel each other out by phase shift, thereby reducing the intensity of the grating beam output from each of the vibrating elements.

2. The ultrasonic probe according to claim 1, characterized in that, In a planar view taken from the depth direction, the shape of the vibrating element is a polygon with more than one pentagon, or at least one side of the vibrating element is a curve.

3. The ultrasonic probe according to claim 1, characterized in that, In a planar view taken from the depth direction, the shapes of the first virtual portion and the second virtual portion are in an asymmetrical relationship centered on the center of gravity of the vibrating element.

4. The ultrasonic probe according to claim 1, characterized in that, The distance between the first virtual center of gravity and the second virtual center of gravity in the array direction, i.e., the distance between virtual centers of gravity, is less than the spacing between the vibration elements in the vibration element array.

5. The ultrasonic probe according to claim 4, characterized in that, When the plurality of vibrating elements are arranged on a plane, the distance between the virtual centers of gravity is half the distance between the vibrating elements.

6. The ultrasonic probe according to claim 4, characterized in that, When the plurality of vibrating elements are arranged on a curved surface, the distance between the virtual centroids is half of the virtual spacing P' between the vibrating elements, wherein, Virtual spacing P' is determined by P' = Psin θg / sin(θg-β) β=(N / 4)*α means, P is the spacing between the vibrating elements, θg is the beam angle of the grating beam, N is the number of aperture vibrating elements, and α is the angular spacing between the vibrating elements.

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