JPS5961400A - Focusing type ultrasonic wave probe - Google Patents

Abstract

PURPOSE:To focus an ultrasonic wave irradiated from a piezoelectric body onto a sound axis with a minute and high sound field, by providing an electrode on both sides and the piezoelectric body having >=2 radii of curvature on both a sound operating side and its opposite side. CONSTITUTION:The electrodes 121, 122 are formed on both sides of a high polymer piezoelectric film 11 and a copper-made reflecting plate 13 is bonded on the electrode 122. Then, the high polymer piezoelectric film 11 is pressed with a metallic die processed in advance to form the sound operating faces having different radii of curvature. Further, the high polymer piezoelectric film 11 is bonded to a cylindrical box 15 having a step part at the inside of the tip, and leads 14, 14 are connected to the electrodes 121, 122, then a support 16 made of epoxy resin is formed. Moreover, an insulating layer 17 is formed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a focused ultrasound probe useful for ultrasound diagnostic equipment.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, as a method for improving the resolution of an ultrasound diagnostic apparatus, ultrasound waves emitted from a piezoelectric body are focused on a single point on an ultrasound propagation medium or a living body.

By the way, conventional ultrasonic probes used in such a method include those in which a piezoelectric body 12 is processed into a concave curved surface as shown in FIG. The 5-sound lens 2 processed into a concave curved surface is integrated, or the first polarization 31 is provided on one side of a flat piezoelectric body 13 as shown in FIGS. A second electrode 32 divided into 7 ring shapes is provided on the other surface,
There are known devices in which ultrasonic waves are emitted by electrically driving the piezoelectric body 13 and focused through mutual interference. All of these ultrasonic probes focus the ultrasonic waves generated from a piezoelectric material on a single point (focal point) on the sound axis based on the concavely processed piezoelectric material, the concave radius of the acoustic lens, or the design of divided electrodes. at this point n) 1 <
It is intended to obtain a high iI\ (sound-wave sound field).

However, the ultrasonic probe (d: sound + I from the focal point
There was a drawback that the ultrasonic sound field suddenly decreased in the slightly forward and backward part of the soil, and the ultrasonic beam became thicker. Therefore, as an ultrasonic probe useful for the ultrasonic BljJ'i device, it is desirable to improve not only the conventional θ1'' resolution in the horizontal direction but also the resolution in the vertical direction at the same time. ing. In order to improve the vertical resolution, the ultrasonic waves emitted from the piezoelectric material are
! The radius of curvature of the concave curved surface is set so as to focus on the -'yV distance pin+ on '1fl. Specifically, for example, the J2 piezoelectric body is subjected to concave surface processing f: by polishing, etc., and an acoustic lens is combined. This is achieved through methods such as Conventional ultrasound probes have short focus (2~4 an, ]11), medium focus (4~8 an), long focus, depending on the L1 ultrasound medium used and the diagnostic site of the subject. It takes a lot of skill and time to accurately diagnose any part by using various types of ultrasound probes depending on the focal point (8 cm or more).

For these reasons, there has recently been a demand for a variable focus type ultrasound probe that can focus ultrasound waves emitted from a single piezoelectric body at an arbitrary point, and such an ultrasound probe has been developed in the Japanese Patent Publication No. 151895 of 1983 has been proposed. This ultrasonic probe uses a polymer piezoelectric material that has been processed in advance to have a concave curve rIjj. By pressurizing or depressurizing the airtight chamber on the back side of the back electrode, the radius of curvature of the concave surface can be varied and the focal point can be arbitrarily set. Selected shi or polymer pressure processed into concave curved surface
i'j, the back side of the back electrode of the body or the 0111 plane is changed by an actuator that moves by excitation of a coil, and the radius of curvature of the concave curved surface is varied, so that the focal point can be arbitrarily selected. However, the above-mentioned ultrasonic probe is required to be equipped with an air mass/decompression device to vary the focus, or to be provided with a complicated circuit (actuator having a single component), resulting in an increase in size. Another disadvantage is that the noise generated from the actuator significantly degrades the performance of the ultrasonic probe.

[target of invention]

The present invention has been made in view of the above circumstances, and is a focusing type that focuses ultrasonic waves emitted from a piezoelectric body in a thin line on the sound axis with a high sound field, and has excellent vertical and horizontal resolution. The purpose is to provide all ultrasonic probes.

[Summary of the invention]

The present invention converts the ultrasonic waves emitted from the EE object into sound by polarizing the double-sided electrode with a piezoelectric material having two or more radii of curvature on both the γf-sounding surface and the opposite surface. This is aimed at improving not only the horizontal resolution but also the vertical resolution as in the past by focusing narrowly and with high aptitude on the axis.

As the electrode material according to the present invention, Au + Ag rN
l g Cr + AZ etc. are used. Furthermore, examples of the means for forming the electrodes include vacuum evaporation, sootering, plating, and the like.

The piezoelectric material according to the present invention includes polyvinyrizofluoride/,
Polymer piezoelectric film such as polyvinyl chloride, polyacrylonitrile, or polyvinylidene fluoride/tetrafluoroethylene, Pl) vinylidene fluoride/ethylene trifluoride, polyaminovinylidene/vinyl 11r acid? , 1? : A polymer piezoelectric film having the common properties of Examples include sheets. In addition, the above polymer piezoelectric film or composite polymer piezoelectric film
lj'/-) (il- A structure in which a plurality of laminated films (or sheets) are laminated so that each of the laminated films (or sheets) vibrates in thickness can also be used as a piezoelectric material.

As mentioned above, the reason for using a polymer piezoelectric film (or a composite type polymer film or sheet) as a piezoelectric material is that it has good processability. PZT' (lead zirconium titanate) and Pb
Ceramic piezoelectric materials such as Tl03 (lead titanate) (
1. This is because processing the piezoelectric body into a concave curved surface is achieved by polishing or the like. Form concave curved surfaces with desired precision,
It is extremely difficult to obtain a uniform thickness. For example, when polishing a ceramic piezoelectric material, the piezoelectric material may be destroyed due to cracks or defects during polishing, or the ultrasonic frequency may be reduced due to distortion or uneven thickness of the piezoelectric material during processing. Variations occur and the performance of the ultrasonic probe is significantly degraded. In addition, in the manufacture of such ultrasonic probes, there are problems with process control during polishing and workability, which lowers the yield due to problems such as 1. It is very difficult to process the song to T/4))).

Therefore, as the piezoelectric material mentioned above, the polymer 1-iE'r
If lt film or the like is used, the workability is significantly superior to that of ceramic or Kunu pressure "iI↓ bodies, and concave surfaces can also be achieved in the cylinder with high accuracy. The above objective is achieved by subjecting the molecular piezoelectric film 1 to zero-resist processing.

Alternatively, a back cover that can be used as a support such as F-1 resin was placed in a container, and a 7ti, 4-back metal thin film, a polymer piezoelectric film, and the metal thin film were placed on the surface of the back cover. After that, press to make a kuhomi, part 1-1
A desired concave curved surface is obtained by curing the back part (A), and a concave mj where the polymer piezoelectric film and the support are integrated
A type ultrasonic probe is obtained.

[Embodiments of the invention]

A focused ultrasonic probe, which is an embodiment of the present invention, will be described with reference to FIGS. 4(a) and 4(b), along with the entire manufacturing method.

[1] Thickness of polymer piezoelectric film 65/Am
Ag films were deposited on both sides of the proposed polyvinyrite fluoride film by vacuum evaporation to a thickness of about 0.0mm.
A 5 μm Ag film was formed. Next, a DC voltage of 5000V was applied to the Ag film on both sides of the film at 100°C.
The polymer piezoelectric film 11 was carved by applying time, and one Ag film was used as the first electrode 121. Next, the other Ag film is appropriately etched to reduce the diameter to 1.
A second electrode 122 having a tripharyngeal diameter was formed. Next, a copper reflector J3 corresponding to a quarter wavelength is adhered to the second electrode 122 using an epoxy adhesive or a cyanoacrylate adhesive /ζ (as shown in FIG. 4(a)).

[11] Next, the polymer piezoelectric film 11 was pressed using a pre-processed mold, and the radius of curvature of the 651 plane of the film was set to 30 mm, 50 mm, and 70 mm from 1ql+. At this time, the acoustic motion rf that creates different radii of curvature
iu;i: They are all set to have the same area, and the curvature radius of 30 mm is for sound (7.5 mmφ, curvature radius of 50 mm)
Between Huff 5 and Wa φ, 10.6 cycles φ, radius of curvature 70 is 1
The diameter was changed from 06 mm to 13.0 mm. Subsequently, the lead wire 14 was connected to the center of the reflection plate 13 and also connected to the ψi1a Fill of the first electrode 12. Next, the piezoelectric film 11 is placed in a cylindrical casing 15 having a step Xl- inside the tip, and the side of the piezoelectric film 1 having the reflection plate 13 is placed inside the casing 15 (g+r) Vc i )'lX position and fixed with adhesive. Incidentally, there is a pore (not shown) in the side wall of the casing 15, through which the lead wire 14 of the first box 7 (the first box 7) passes through. was filled with epoxy resin and cured to form a support 16. Furthermore, the first electrode 721 (111
Q ahead of 1 housing 15! Apply acrylic ester ultraviolet curing paint inside the ij and irradiate it with ultraviolet rays to reduce the thickness to 12μ.
An insulating layer 17 of n1 was formed (as shown in FIG. 4(b)).

The focused ultrasonic probe 'F manufactured as described above has three radii of curvature on both sides (equal radii of curvature on the acoustically active surface side of the polymer IIE film 11), as shown in FIG. 4(b). 1 and a second electrode 12 on the side opposite to the acoustic active surface.
2. A reflection plate 13 is provided, and the first electrode 12 and the reflection plate 1 are provided.
A lead bond 14° 14 is provided on each of the film 11.
is provided at the tip of the cylindrical casing 17, a support 16 is provided in a part of the casing 15 on the reflection plate I3 side, and an insulating layer 17 is provided in the tip of the casing 15 on the first electrode 121 side. It has a structure with

According to the focused ultrasonic probe of the present invention, the polymer piezoelectric film 1) is 3050.70 rrr compared to the acoustic type 1.
Because it has a structure with a radius of curvature of 3 heel of yn,
It is possible to focus the ultrasonic wave θ emitted from the film 11 narrowly and in a narrow sound field on the sound axis, and to form the ultrasonic focusing points A, B, and C as shown in FIG. In addition to improving the resolution in the directional direction, we also achieved the resolution in the vertical direction, which was previously unattainable. The diameter of the example is 0.5 m at 50 m (frtl) from the center axis of the ultrasonic probe.
A nylon thread of 2.0 mm in length was set up with a knot, and the intensity of the reflected ultrasound wave (echo wave) was plotted when the thread was moved in the xry direction. In addition,
4 in Figure 5 is polymer 17, film, 51152
are the first . . . on both sides of the film 4. 6 represents a second electrode, 6 represents a reflective plate, and 7 represents an insulating layer. As a result, the comparative example is x
= (1,l:!i in the center above 11+y
= 53 mm % RIJ is also a polymer piezoelectric film 1)
The intensity of the echo wave was maximum only at a distance of 53 mmfqj [from the surface. On the other hand, in the example, the intensity of the echo wave reached its maximum three times at 80 points as shown in FIG. It can be confirmed that the focused ultrasonic probe of this example is superior to the focused ultrasonic probe of the comparative example.

Note that the focused ultrasonic probe 1 according to the present invention may be the one shown in FIG. Focused ultrasonic probe shown in Figure 7,
Compared to the one shown in FIG. 4(b), the first electrode 12. of the polymer piezoelectric film 1. On the opposite side, a plurality of polarized ring-shaped second electrodes 22 are formed on the Ag film and the copper reflector 4 with a ring-shaped gap of 1 width in between.
is provided 11, and it is read in 22 of each edition 2.
The I springs 14', 14'... are connected to each other. Here, the first electrode 121 and the second electrode 2
2 is given pressure ↑b, but the portion of the groove 2 where the second electrode 22 is not formed becomes non-piezoelectric.

According to the focused ultrasound probe shown in FIG.
First electrodes 12 on both sides of the polymer piezoelectric film 11. and a plurality of ring-shaped molecules separated by grooves 21. P,
Since piezoelectricity is thinly distributed only in the second electrode, the non-piezoelectricity portion of the film lx l l is accompanied by a large loss and piezoelectric constant = 0 (or electromechanical coupling engagement -0
). Therefore, the piezoelectric non-imparting part acts as a sound absorbing part and has a good air quality. It becomes H-body.

As a result, the river 'Fl'j
Electrical and acoustic coupling between the parts is eliminated, and crosstalk is prevented.The focused ultrasonic probe shown in FIG. Four waves can be obtained by focusing in a line on the axis.

When we plotted the intensity of the ultrasound echo wave under the same conditions as the focused ultrasound probe shown in Figure 4(b), we found that it was 8.
Actual jj, ω results similar to those in the J'j, f5 diagram were obtained.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a focusing ultrasonic probe that has excellent resolution in the vertical and horizontal directions and can provide a clear image when used in an ultrasonic diagnostic apparatus.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a conventional ultrasonic probe, FIG. 3(a) is a plan view of another conventional ultrasonic probe, and FIG. ), Figure 4(a)
, (b) is a top view of H No. 1 showing the focused ultrasonic probe-F of the present invention in the order of manufacturing steps, FIG. Figure 6 is similar to Figure 4 (b
) An explanatory diagram showing the experimental results using the illustrated focused ultrasonic probe. 1)...Molecular piezoelectric film, 121 + 122
+22... Electrode, 13... Reflector, 15... Housing, 16... Support, 17... Insulating layer, 2...
groove. Applicant's agent Patent attorney Takehiko Takehiko Figure 1 4.

Claims (1)

[Claims] 1. First . With the second electrode, the acoustic operation 1r
A focused ultrasonic probe characterized in that both the ii side and the opposite side are provided with piezoelectric bodies having two or more radii of curvature. 2. Divide the second electrode on the side opposite to the acoustically active surface of the piezoelectric body into a plurality of ring-shaped electrodes, and impart piezoelectricity only to the divided electrodes and the first electrode. A focused ultrasonic probe according to item 1 of the patent claim in box 1.1x having /ite as a feature. 3. A focused ultrasonic probe according to claim 1, characterized in that a polymer piezoelectric film or a composite polymer piezoelectric sheet is used as the piezoelectric material. #'F A focused ultrasonic probe according to claim 1.