JP4153326B2 - 2D array ultrasound probe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic probe including a two-dimensional array of vibration element arrays.
[0002]
[Prior art]
In recent years, an ultrasonic probe in which vibration elements are two-dimensionally arranged has become widespread for three-dimensional image formation using ultrasonic waves. 2. Description of the Related Art Conventionally, as a two-dimensional array of vibration element arrays, as disclosed in Patent Document 1, a transmission / reception surface in which square or rectangular vibration elements are arranged in a vertical and horizontal lattice pattern is generally used.
[0003]
However, in the case of a vertical and horizontal grid arrangement, the directivity of ultrasonic waves is greatly different between the vertical and horizontal directions, which are the grid arrangement directions, and the other oblique directions. For this reason, there is a problem that when the beam is tilted in the two-dimensional scanning of the ultrasonic beam, the sensitivity greatly varies depending on the beam scanning direction.
[0004]
With respect to such a problem, in the ultrasonic probe disclosed in Patent Document 2, regular hexagonal vibration elements are arranged in a honeycomb shape, or rectangular vibration elements are alternately arranged like brickwork. The difference in sensitivity depending on the beam scanning direction is reduced by forming a honeycomb array.
[0005]
In Patent Document 3, the piezoelectric plate is cut in three different directions by 120 degrees to form an element array in which equilateral triangle elements are spread, and six equilateral triangle elements are connected to the same electrode. And operate as a regular hexagonal element to form a honeycomb-like array of regular hexagonal elements similar to that of Patent Document 2.
[0006]
[Patent Document 1]
JP-A-6-254089 [Patent Document 2]
US Pat. No. 6,469,422 [Patent Document 3]
US Pat. No. 6,503,204 Specification
[Problems to be solved by the invention]
However, the honeycomb array shown in Patent Document 2 has a problem that it is difficult to manufacture. That is, a general square or rectangular lattice arrangement can be realized by a relatively simple process of cutting a piezoelectric plate with vertical and horizontal straight lines by a dicing saw, whereas a honeycomb-like arrangement is not possible with a linear cut. This cannot be realized, and complicated work such as arranging regular hexagonal or rectangular vibration elements in a honeycomb shape is necessary.
[0008]
To deal with such a manufacturing problem, in Patent Document 2, a piezoelectric plate is linearly cut vertically and horizontally to form a grid of rectangular sub-elements, and then two adjacent sub-elements are electrically coupled to each other. A system has been proposed in which an approximate honeycomb-like arrangement is realized by functioning as a single vibration element and staggering the combination of this combination for each stage.
[0009]
In this method, the piezoelectric plate may be diced by a straight cut, and it is not necessary to rearrange the piezoelectric plate into a honeycomb shape. However, in this method, the gap between the electrically coupled sub-elements is filled with the conductive filler, while the gap between the non-coupled elements is left in the space or filled with the non-conductive filler. It is necessary to change the handling depending on the gap, and this point is complicated in the process. In addition, in the approximate honeycomb arrangement by staggered arrangement of rectangular elements, even if the arrangement structure is honeycomb, the shape of the element itself is rectangular, and therefore the direction dependency of sensitivity is larger than that of a regular hexagonal honeycomb arrangement. There is a problem.
[0010]
Although the method of Patent Document 3 can form a regular hexagonal honeycomb structure relatively easily, there is a problem that signal crosstalk easily occurs between adjacent elements because the sides of adjacent vibration elements are in contact with each other. .
[0011]
The present invention has been made in view of such problems, and is a two-dimensional array ultrasonic probe that is less dependent on the direction of sensitivity, is relatively easy to manufacture, and can reduce crosstalk of signals between vibration elements. The purpose is to provide.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a two-dimensional array ultrasonic probe according to the present invention includes a plurality of effective vibration elements used for at least one of transmission and reception of ultrasonic waves, and ultrasonic transmission / reception interposed between the effective vibration elements. The ineffective vibration element not used in the above includes a vibration element array formed by dividing the piezoelectric plate by at least three parallel division groove groups having different directions.
[0013]
The at least three groups of parallel dividing grooves are three groups of parallel dividing grooves having different angles by 120 degrees, and each of these parallel dividing grooves is composed of parallel dividing grooves of equal intervals.
[0014]
In the vibration element array, a repeating pattern of a hexagonal star structure in which ultrasonic transmission / reception surfaces are composed of vibration elements having regular hexagons and equilateral triangles is formed by the three parallel divided groove groups having angles different from each other by 120 degrees. It is formed.
[0015]
In a further preferred aspect, the regular hexagonal vibration element is the effective vibration element, and the regular triangular vibration element is the ineffective vibration element.
[0016]
In a further preferred aspect, only the vibration element included in a substantially circular area within a predetermined radius from the center of the vibration element array is used as the effective vibration element among vibration elements having a regular hexagonal ultrasonic transmission / reception surface. And
[0017]
In another preferred aspect of the present invention, among the plurality of vibration elements divided by the at least three parallel division groove groups, the vibration element having a regular polygonal ultrasonic transmission / reception surface having more than four sides. Is the effective vibration element.
[0018]
In a further preferred aspect, among the vibration elements having the regular polygonal ultrasonic wave transmitting / receiving surface, only the vibration elements included in a substantially circular region within a predetermined radius from the center of the vibration element array are set as the effective vibration elements. It is characterized by.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
[0020]
FIG. 1 is a diagram showing a configuration example of a vibration element array 10 of an ultrasonic probe according to the present invention.
[0021]
As shown in this figure, the vibration element array 10 of this embodiment includes regular hexagonal columnar vibration elements 12 and 16 and a regular triangular columnar vibration element 14. When viewing the ultrasonic transmission / reception surface, this vibration element array 10 is composed of regular hexagonal (regular hexagonal columnar) vibration elements 12 and 16 each having a regular triangular (regular triangular columnar) vibration element 14 across a dividing groove 18. So-called hexagram structure repeating pattern. That is, the regular hexagonal surfaces of the vibrating elements 12 and 16 are aligned in the same direction with the same size, and the regular triangular surface of the vibrating element 14 is between the regular hexagonal surfaces of the adjacent vibrating elements 12 or 16. It exists, and the length of each side of the regular triangle and regular hexagon is equal.
[0022]
As shown in FIG. 2A, the vibration element array 10 is formed by cutting one piezoelectric plate made of a piezoelectric material into three cutting directions α, β, and γ using a dicing saw or the like. can do. Here, as shown in FIG. 2B, these cutting directions α, β, γ form an angle of 120 ° with each other (can be regarded as different by 60 °), and each of these cutting directions α, β, Cut is performed in parallel at the same cut pitch P _c for γ. By appropriately defining the positional relationship between the parallel lines in each cutting direction, the elements can be divided so as to form a hexagonal star-shaped repetitive structure as shown in FIG. A groove in each cutting direction formed by cutting becomes a divided groove 18. The dividing groove 18 can be filled later with a filler.
[0023]
Such a vibration element array 10 can be formed, for example, by performing the above-described cutting with a dicing saw or the like from one surface of a piezoelectric plate having electrodes formed on both surfaces. Cutting in this case includes both the case where the piezoelectric plate is completely cut from one surface to the other surface and the case where the cutting is performed only halfway. In any case, since the electrodes on at least one surface are divided for each vibration element 12, 14, and 16, each vibration element 12, 14, and 16 can be operated individually.
[0024]
The configuration of FIG. 1 shows an example in which the above-described cutting is performed on a rectangular piezoelectric plate.
[0025]
In a preferred configuration, only the regular hexagonal vibration elements 12 and 16 of the vibration element array 10 divided into elements as described above are used for transmission or reception, and the equilateral triangular vibration element 1 is used for either transmission or reception. Also do not use. That is, in this case, the regular hexagonal vibration elements 12 and 16 function as effective vibration elements, and the regular triangular vibration element 14 becomes an invalid vibration element. In this configuration, as shown in FIG. 3, the element pitch P _e connecting the centers of effective regular hexagonal vibrating elements 12 or 16 is equal to each other in the three cut directions α, β, and γ. For example, when the cut pitch P _c is 0.3 mm, the element pitch P _e is 0.346 mm.
[0026]
As described above, by using the vibration elements 12 and 16 having the regular hexagonal ultrasonic transmission / reception surface, the direction dependency of the sensitivity can be made smaller than that of the vibration element having a square or rectangular ultrasonic transmission / reception surface. From the viewpoint of direction dependency, it is ideal to make the ultrasonic wave transmitting / receiving surface circular, but it is extremely difficult to manufacture an array of such circular vibration elements. On the other hand, in the case of the present embodiment, an array of vibrating elements having characteristics closer to circular elements than in the past is formed by a relatively simple process of cutting a piezoelectric plate along a group of parallel lines in three directions. be able to.
[0027]
Further, the arrangement of the vibration element 12 of the regular hexagon of the same cut direction, as shown in FIG. 3, offset and odd columns (first 2n ± 1 line) even columns by (a 2n columns) and de 1 / 2P _e It is an array. This is true for all cut directions α, β, and γ. Therefore, when the vibration element array 10 is viewed as a whole, the vibration element 12 functions as an array in which the vibration elements 12 are arranged at half the pitch P _e between the elements in the respective cut directions. For this reason, the grating lobe of the beam profile in each cut direction can be reduced as compared with a square lattice vibration element array having an equivalent transmission / reception surface size.
[0028]
Further, in this configuration, the sides of adjacent regular hexagonal vibration elements 12 or 16 are separated by regular triangular vibration elements 14 that are not used for transmission and reception. With such a configuration, effective vibration elements used for at least one of transmission and reception are only in contact with each other at their apexes, so that transmission or reception signal crosstalk between adjacent vibration elements is also reduced.
[0029]
Further, in a more preferable configuration, as shown in FIG. 1, among the regular hexagonal vibration elements 12 and 16, only the vibration elements 12 included in the regular hexagonal region centered on the center point of the vibration element array 10 are effective. The vibrating element 16 outside is not used for transmission / reception. By doing in this way, the shape of the whole effective vibration element group can also be approximated to a circle, and as a result, the direction dependency of sensitivity can be reduced. A configuration in which a regular hexagonal vibration element included in a substantially circular region within a predetermined radius from the center of the vibration element array 10 is used as an effective vibration element is also suitable. In FIG. 1, the invalid vibration element is hatched to clearly distinguish the effective element from the invalid element.
[0030]
FIG. 4 is a diagram schematically illustrating the appearance of an ultrasonic probe 100 including the vibration element array 10 illustrated in FIG. When such an ultrasonic probe 100 is used, when the ultrasonic beam is two-dimensionally scanned, the difference in sensitivity depending on the beam direction can be made smaller than that of an array of square lattices. Good sensitivity characteristics equivalent to the honeycomb structure can be realized.
[0031]
As described above, the vibration element array 10 of the present embodiment can be manufactured by a manufacturing process far simpler than the regular hexagonal honeycomb structure shown in Patent Document 2, and achieves good sensitivity characteristics equivalent to the manufacturing process. it can.
[0032]
FIG. 5 is a diagram showing the structure of another vibration element array 20 according to the present invention. This figure is a diagram schematically showing a state in which the vibration element array is viewed from the ultrasonic transmission / reception direction.
[0033]
In the example of FIG. 5, the piezoelectric plate is cut in parallel in four directions A, B, C, and D to form a two-dimensional array of regular octagonal columnar vibration elements 22 having a regular octagonal ultrasonic wave transmitting / receiving surface. is doing.
[0034]
Here, the A direction and the B direction are orthogonal to each other. The C direction and the D direction form an angle of 45 ° with respect to the A direction and are orthogonal to each other. About each direction of C and D, it cuts in parallel with the same cut pitch P1. For each of the A and B directions, two cutting pitches P1 (the same pitch as the C and D directions) and P2 smaller than that are alternately repeated to perform parallel cutting. A regular octagon as shown in FIG. 5 is obtained by appropriately determining the positional relationship between the ratio of the cut pitches P1 and P2 and the parallel lines in the cut directions of A, B, C, and D (which become the divided grooves 24). A two-dimensional array of effective vibration elements 22 can be formed.
[0035]
Of the vibration element array 20 thus formed, only the regular octagonal vibration element 22 is used as an effective vibration element for at least one of transmission and reception, and the other vibration elements are invalid vibration elements. Thereby, since the ultrasonic wave can be transmitted and received by the regular octagonal vibration element 22 which is more circular than the regular hexagon, the direction dependence of the sensitivity of the ultrasonic probe can be improved.
[0036]
As described above, the example of FIG. 5 can also form a two-dimensional array of vibration elements 22 with less direction dependency by a simple operation of cutting a piezoelectric plate along a straight line.
[0037]
In the example of FIG. 5 as well, only the regular octagonal vibration element 22 included in a substantially circular region within a predetermined radius from the center of the vibration element array 20 is used as an effective vibration element, so that an ultrasonic probe is used. It is possible to improve the direction dependency of the sensitivity of the entire touch element.
[0038]
【The invention's effect】
As described above, in the ultrasonic probe according to the present invention, the element is divided by the group of three or more parallel division grooves in different directions, and therefore, an ultrasonic transmission / reception surface having three or more sides directed in different directions is provided. A vibrating element is formed. In the conventional square lattice vibration element array, the side of the ultrasonic wave receiving surface of each vibration element has only two directions, but in the present invention, there are three or more directions. Can improve. In addition, since the vibration element array according to the present invention has a structure that is divided into a plurality of vibration elements by a combination of parallel division groove groups, a process such as cutting for element division is performed along parallel straight lines. The vibration element array can be formed by a relatively simple operation of repeating in a plurality of directions. Further, in the present invention, since the ineffective vibration element is interposed between the effective vibration elements, signal crosstalk between the effective vibration elements can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a vibration element array of an ultrasonic probe according to the present invention.
FIG. 2 is a diagram for explaining the main part of the manufacturing process of the transducer array of the ultrasonic probe according to the present invention.
FIG. 3 is a diagram for explaining a relationship between effective vibration elements.
4 is a diagram schematically showing the appearance of an ultrasonic probe including the vibration element array illustrated in FIG. 1. FIG.
FIG. 5 is a diagram showing the structure of another vibration element array according to the present invention.
[Explanation of symbols]
10 vibration element array, 12, 16 vibration element (regular hexagon), 14 vibration element (regular triangle), 18 dividing groove.

Claims (5)

A plurality of effective vibration elements used for at least one of transmission and reception of ultrasonic waves and an ineffective vibration element that is not used for ultrasonic transmission / reception interposed between the effective vibration elements are parallel to at least three groups whose directions are different from each other. A vibration element array formed by dividing the divided groove group ,
The at least three groups of parallel dividing grooves are three groups of parallel dividing grooves that are different from each other by 120 degrees, and each of these parallel dividing grooves is composed of equally divided parallel dividing grooves,
In the vibration element array, a repeating pattern of a hexagonal star structure in which ultrasonic transmission / reception surfaces are composed of vibration elements having regular hexagons and equilateral triangles is formed by the three groups of parallel division grooves having angles different from each other by 120 degrees. A two-dimensional array ultrasonic probe characterized by having 2. The two-dimensional array ultrasonic probe according to claim 1, wherein the regular hexagonal vibration element is the effective vibration element, and the equilateral triangular vibration element is the ineffective vibration element . 3. The vibration element included in a substantially circular region within a predetermined radius from the center of the vibration element array among the vibration elements having a regular hexagonal shape as the ultrasonic transmission / reception surface is defined as the effective vibration element. 2D array ultrasound probe. A plurality of effective vibration elements used for at least one of transmission and reception of ultrasonic waves and an ineffective vibration element that is not used for ultrasonic transmission / reception interposed between the effective vibration elements are parallel to at least three groups whose directions are different from each other. A vibration element array formed by dividing the divided groove group,
Of the plurality of vibration elements divided by the at least three groups of parallel division grooves, a vibration element having a regular polygonal ultrasonic transmission / reception surface having more than four sides is defined as the effective vibration element. A two-dimensional array ultrasonic probe. The vibration element included in a substantially circular region within a predetermined radius from the center of the vibration element array among the vibration elements having the regular polygonal ultrasonic transmission / reception surface is the effective vibration element. 4. The two-dimensional array ultrasonic probe according to 4.

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