JPH0511478B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an ultrasonic probe in which a plurality of piezoelectric vibrators are arranged in a curved shape. It is used as a wave transmitter and receiver.

(Background of the Invention) In general, electronic scanning type ultrasonic probes include a sector type which scans by simultaneously applying drive pulses with different delay amounts to each piezoelectric vibrating body arranged in a row. There is a linear method in which driving pulses are sequentially applied to each piezoelectric piece for scanning. For example, in the sector method, since the ultrasonic wave transmission and reception directions can be scanned in a fan-like manner, it is said that a wide range of exploration can be performed with a reduced number of piezoelectric vibrating elements.

FIG. 2 is a sectional view of this type of array type probe for electronic scanning. That is, this array type probe has electrodes 2 on both main surfaces of a plurality of piezoelectric pieces, for example, lead zirconate titanate, commonly known as PZT, shown by reference numeral 1 in the figure.
is formed and fixed to a backing material 3 that absorbs unnecessary ultrasonic waves, and an acoustic matching layer 4 is provided on the ultrasonic wave transmitting/receiving surface side of each piezoelectric piece 1. Then, for example, a filler 5 is applied between the piezoelectric pieces 1, a plurality of piezoelectric pieces 1 are treated as one block and an independent piezoelectric vibrating body 6, and this piezoelectric vibrating body 6 is driven by a sector or linear method to improve resolution, etc. I try to get information of good quality.

(Prior Art to the Invention) Incidentally, in recent years, in this type of array type probe, as shown in the front cross-sectional view of FIG. 8
(a) is fixed on a holding table 9 having a convex surface, for example (b), and an acoustic matching layer 10 is formed continuous on the wave transmitting/receiving surface of each piezoelectric piece 7 arranged on a curved surface. There is a method that attempts to widen the area in the direction of the wave plane for transmitting and receiving sound waves, thereby making it possible to survey a wide area (reference document: JP-A-59-229999 Publication "Method for manufacturing an ultrasonic probe").

(Disadvantages of the prior art) However, in this array type probe, the acoustic matching layer 1
0 is continuously formed on the ultrasonic wave transmitting/receiving surface side of a plurality of piezoelectric pieces 7 arranged on a curved surface. Therefore, when transmitting and receiving ultrasonic waves, adjacent piezoelectric pieces 7 interfere with each other and change the sound field characteristics. There are drawbacks to it. Additionally, in general, an acoustic matching layer is placed on each piezoelectric piece to prevent propagation loss of the acoustic energy of the ultrasound and ensure efficient transmission and reception when the ultrasonic waves propagate between the detected object and the piezoelectric piece. It is said that it is necessary to apply the coating to a thickness of λ/4. However, according to the above example, the acoustic matching layer 10 is applied after the piezoelectric pieces 7 are arranged on the curved surface, so that the thickness is uniform on the wave transmitting and receiving surface of each piezoelectric piece 7 arranged on the curved surface, and λ/ 4, it becomes extremely difficult to form. For this reason, for example, if the thickness of the acoustic matching layer 10 of each piezoelectric piece differs, the propagation path length of the ultrasonic wave will also differ, and good sound field characteristics may not be obtained.

(Objective of the invention) The present invention expands the ultrasonic wave transmission and reception area to enable wide-range exploration, prevents mutual interference of piezoelectric vibrators by the acoustic matching layer, and keeps the ultrasonic propagation path length of the acoustic matching layer constant. The purpose of the present invention is to provide an array type ultrasonic probe with excellent sound field characteristics and a method for manufacturing the same.

(Features of the Invention) The first feature of the present invention is that a plurality of piezoelectric vibrators are arranged on a curved surface, and the acoustic matching layer is formed independently for each of the piezoelectric vibrators and is a plane parallel to the ultrasonic wave transmitting/receiving surface. The second feature of the present invention is that after the surface of the backing material is made parallel to the reference plane and an independent acoustic matching layer is applied to the piezoelectric vibrator attached to the surface,
The manufacturing method involves fixing the backing material onto the curved surface of the holding table.

(Example of the first invention) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Figure 1a is a front sectional view of the ultrasonic probe of the present invention, Figure 1b is a cross-sectional view taken along line A-A' in Figure 1a, and Figure 1c is a cross-sectional view of the ultrasonic probe of the present invention.
is a side cross-sectional view taken along line BB' in figure a.

In the figure, reference numeral 11 indicates a piezoelectric vibrating body, and this piezoelectric vibrating body 11 includes, for example, four piezoelectric pieces 13a, 13b, 13c, and 13d with electrodes 12 formed on both main surfaces.
Four blocks are arranged on the outer peripheral surface of the backing material 14, with each block being one block. The bucking material 14 is made of a flat plate-like elastic flexible material made of vinyl chloride mixed with ferrite powder. It is formed into a curved shape that is fixed to a holding base 15 that protrudes from the top. Furthermore, the bucking material 14 is provided with cutting grooves 16 that divide the piezoelectric vibrating body 11 at predetermined intervals, and each part between the cutting grooves 16 to which the piezoelectric vibrating body is fixed has a linear shape. That is, bucking material 16
The overall shape of the piezoelectric vibrator is curved, and the fixed portion of each piezoelectric vibrator is straight. In the figure, reference numeral 18 indicates a grounding lead wire that commonly connects both sides of the electrodes 12 on the front side to obtain symmetrical sound field characteristics, and 19 indicates a grounding lead wire that connects the electrodes 12 on the back side alternately from both sides of each piezoelectric vibrator 11. This is a metal foil derived from The ultrasonic wave transmitting/receiving surface of each piezoelectric vibrator 11 includes the first layer 20a filled between the piezoelectric pieces 13 and the surface excluding both sides where the grounding lead wire 18 is attached, and the second layer 20b. A two-layer acoustic matching layer 20 is coated on the entire surface. That is, the main surface of the piezoelectric vibrator fixed on the backing material and the surface of the acoustic matching layer are linear parallel planes. A filler 21 having an acoustic impedance value different from that of the acoustic matching layer 20 is provided between the piezoelectric vibrators 11 and in the grooves 16 .

Therefore, in the ultrasonic probe having this configuration, since the ultrasonic wave transmitting/receiving surface is arranged in a substantially curved shape, the ultrasonic wave transmitting/receiving direction can be expanded. Further, the acoustic matching layer 20 is applied independently to each block vibrating body, and a filler material 21 having different impedance is placed between them.
, it is possible to prevent mutual interference via the acoustic matching layer. Since the fixed portion of each piezoelectric vibrating body in the bucking material 16 is made linear, the piezoelectric vibrating body 11 is made into a flat shape rather than a curved surface,
Furthermore, the acoustic matching layer 20 can also be made planar. Therefore, the thickness of the acoustic matching layer 20 can be easily controlled to a constant thickness. Therefore, this ultrasonic probe can not only expand the transmission and reception directions of ultrasonic waves but also have good sound field characteristics. Further, in this embodiment, each piezoelectric piece 13a forming the piezoelectric vibrating body 11,
The first acoustic matching layer 20a is buried between 13b, 13c, and 13d, and the acoustic matching layer 20 is continuously formed on the ultrasonic wave transmitting/receiving surface side of each piezoelectric piece 13, so that each piezoelectric piece 13a, 13b, 13c,
Vibration in the thickness direction becomes easier to combine between 13d,
It is expected that the ultrasonic wave transmission and reception sensitivity of each piezoelectric vibrator 11 will be improved.

(Embodiments of the Invention) The manufacturing method of the present invention will be explained below with reference to process diagrams a to i in FIG. 4. In the description of this embodiment, the same parts as those described above will be given the same numbers.

First, the backing material 14 is attached to the processing table 22 with the bottom surface as a reference surface (FIG. 4a), and the surface of the bucking material 14 is maintained parallel to the reference surface by, for example, polishing (FIG. 4a). b), on the surface of this backing material 14 is a rectangular piezoelectric plate 23 made of, for example, PZT, which has electrodes 12 on both main surfaces and has metal foils 19 led out from both sides in the longitudinal direction on the back surface.
(Partial view of c in the same figure). Note that the parallelism of the surface of the backing material 14 with respect to the reference plane is measured, for example, by measuring each distance from the reference plane. Next, the piezoelectric plate 23 is divided and cut into a plurality of piezoelectric pieces 13 by providing a first cutting groove 24 in the width direction that reaches the bucking material 14 (partially normal cross section in FIG. 4d). Next, both sides of the surface of each piezoelectric piece 13 are masked with, for example, adhesive tape 25 (plan view of FIG. The first acoustic matching layer 20a is formed by polishing to λ/4 of the acoustic wave wavelength, and the adhesive tape 25 is removed (as shown in the side cross-sectional view of FIG. 5). Next, both sides of each piezoelectric piece 13 are newly masked, and the second acoustic matching layer 20b is similarly placed on the first
(cross-sectional view of FIG. 4g). Next, a plurality of piezoelectric pieces 13a, 13b,
13c and 13d as one block, a second kerf 26 deeper than the first kerf 24 that reaches the backing material 14 from the surface of the second acoustic matching layer 20b and also cuts the metal foil 19 in each block. is provided and divided into blocks to form each piezoelectric vibrating body 11 (fourth
Partial front sectional view of Figure h). Next, the backing material 14 to which the acoustic matching layer 20 and each piezoelectric piece 13 are integrally fixed is removed from the processing table 22, and the backing material 14 is fixed so that its bottom surface is aligned with the curved surface of the holding table 15, The wave transmitting/receiving surface formed by the piezoelectric vibrating body 11 is approximately curved (FIG. 4i). At this time, the outer circumferential surface of the bucking material 14 to which each piezoelectric vibrating body 11 is adhered becomes a straight line in the tangential direction to each curved surface before bending due to the elasticity of the bucking material 14.
As explained in FIG. 1, each piezoelectric piece 1
Grounding lead wires 14 are connected to both sides of the surface of the piezoelectric piece 11 to commonly connect the surface electrodes of each piezoelectric piece 11, and between each piezoelectric vibrating body 11 and between the second cut groove 23 and each piezoelectric piece 13.
A filler 21 made of, for example, epoxy resin having an acoustic impedance value different from that of the acoustic matching layer 16 is applied to both sides of the surface.

Therefore, according to this manufacturing method, since the surface of the bucking material 14 is made parallel to the reference plane 22 of the processing table and the acoustic matching layer 20 is formed on each piezoelectric piece 11, each acoustic matching layer 20a, 20b The thickness can be reliably set to λ/4. Then, the space between each piezoelectric vibrating body 11 filled with the acoustic matching layer 20 is cut by providing a second cut groove 26 that reaches the backing material 14, and after making the acoustic matching layer 20 independent for each piezoelectric vibrating body. Since this backing material 14 is fixed on the curved surface of the holding base 15, the parallelism of the acoustic matching layer 20 is not impaired and its thickness is made uniform to λ/
It can be maintained at 4. Therefore, with this manufacturing method,
By keeping the propagation distance of the ultrasonic waves through the acoustic matching layer 20 constant, mutual interference between the piezoelectric vibrators caused by the acoustic matching layer can be prevented, and an ultrasonic probe capable of wide-range exploration can be provided. Furthermore, according to this embodiment, the external force when the bucking material 14 is bent is concentrated and absorbed by the cut grooves 26 due to the elasticity of the bucking material 14. It is easily fixed onto the curved surface of the holding base 15, and the linearity of the surface of the backing material 14 is not impaired. Therefore, the directions of ultrasonic wave transmission and reception of each piezoelectric vibrating body 11 do not vary due to external force during bending.
Since the direction is perpendicular to the tangent to each curved surface, directivity characteristics as specified can be obtained.

(Other Matters) In the description of the embodiments of the present invention, the piezoelectric vibrating body has been explained with four piezoelectric pieces as one block, but the present invention is not limited to this, and for example, one piezoelectric piece may be used as one block. Needless to say, a piezoelectric vibrator may also be used. Further, in this manufacturing method, the cut grooves 26 are provided between the piezoelectric vibrating bodies on the surface side of the bucking material 14, and the cut grooves 26 are curved into the holding base 22.
For example, as shown in the sectional view in FIG. 5a, the backing material 14 may be provided on both sides between the piezoelectric vibrating body 11 on both main surfaces of the backing material 14, or as shown in the sectional view in FIG. 5b. The backing material 14 to which the piezoelectric vibrating body 11 is attached is provided at multiple locations on the bottom side of the backing material 14 to appropriately disperse and absorb external forces during bending, taking into consideration the elasticity and other materials of the backing material 14. The linearity of the surface may not be impaired.

(Effects of the Invention) As described above, the present invention expands the transmission and reception area of ultrasonic waves, enables wide-range exploration, prevents mutual interference of block vibrators by the acoustic matching layer, and provides an array type device with excellent sound field characteristics. An ultrasonic probe and a method for manufacturing the same can be provided.

[Brief explanation of the drawing]

Figure 1 is a diagram of the ultrasonic probe of the present invention, and the figure a
1 is a front sectional view, FIG. FIG. 2 is a front cross-sectional view illustrating the general configuration of an array type probe, and FIG. 3 is a cross-sectional view showing a conventional ultrasonic probe and a schematic process thereof. Figure 4 a, b, c, d, e,
f, g, h, and i are process diagrams explaining the manufacturing method of the ultrasonic probe of the present invention, and Figures 5a and 5b are cross-sectional views of other examples of the backing material used in the present invention. It is. 11...Piezoelectric vibrating body, 13...Piezoelectric piece, 14...
...Butting material, 15...Holding stand, 16...Cutting groove.

Claims (1)

[Scope of Claims] 1. A holding table having a curved surface, a backing material fixed on the holding table, a piezoelectric vibrating body composed of a plurality of piezoelectric pieces arranged on the backing material, and a piezoelectric vibrating body arranged on the backing material. an acoustic matching layer matching provided for each piezoelectric vibrating body, the backing material having a curved surface as a whole and a fixed part of each piezoelectric vibrating body having a linear shape, and the piezoelectric vibrating body being fixed on the backing material. An ultrasonic probe characterized in that a main surface and a surface of the acoustic matching layer are linear parallel planes. 2. A piezoelectric plate is pasted on a backing material whose surface is parallel to a linear reference plane, and a first cutting groove reaching the backing material is provided to divide the piezoelectric plate into a large number of piezoelectric pieces. With a plurality of piezoelectric pieces as one block, second cut grooves deeper than the first cut grooves are provided in the backing material to form a plurality of piezoelectric vibrating bodies, and independent acoustic waves are formed on the ultrasonic wave transmitting and receiving surfaces of the piezoelectric vibrating bodies. After providing a matching layer to form an integrated piezoelectric vibrating body, the backing material of the integrated piezoelectric plate vibrating body is fixed onto the curved surface of the holding base, and the main body fixed on the backing material of the piezoelectric vibrating body is fixed. A method for manufacturing an ultrasonic probe, characterized in that the surface and the surface of the acoustic matching layer are formed as linear parallel planes.