JPS63163162A - Array type ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain a vibrator with a wide frequency characteristic and a broad converging range, by making an ultrasonic wave radiating surface alone of a rectangular vibrator concave to set the curvature of a matching layer less than that of the concave surface. CONSTITUTION:In the manufacture of vibrators 2, one side alone of a piezo-electric ceramic substrate is made concave with a uniform thickness and in the length corresponding to a specified number of elements, and after electrodes are provided on both sides thereof, polarization is performed. After being bonded on a packing material 1, the substrate i cut up with a specified width to obtain a plurality of vibrators 2. Then, a semi-cylindrical die is prepared with the curvature thereof less than that of the vibrator 2 and a polyester film as a second matching layer 4 is mounted on the die. Then, a thermosetting epoxy resin as a first matching layer 3 is applied on the vibrator, the die having the polyester is pressed against the resin and the layers 3 and 4 are solidified to integrate. Thereafter, when the die is removed, a desired array type probe is obtained. This provides sound field characteristic in immersion superior to that when using the conventional acoustic lens as shown by a curve 21.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to an ultrasonic probe used for ultrasonic diagnosis and ultrasonic flaw detection.

(Conventional technology) Conventionally, as a method for increasing the azimuth resolution in ultrasonic diagnosis and ultrasonic flaw detection, it has been put into practice to focus an ultrasonic beam by providing an acoustic lens or using a concave transducer. ing.

Array-type ultrasound probes, which have been widely used in ultrasound diagnosis in recent years, have a configuration in which rectangular transducers are arranged in parallel in one direction, and the arrangement direction is determined by electronic scanning. However, in the direction perpendicular to the arrangement direction, the method is similar to the method described above, and acoustic ins is usually used. However, when using a concave or convex acoustic lens or a concave vibrator, it is difficult to process these with high precision.
Since the ultrasonic beam is point focused, the ultrasonic beam width is narrow and the range of high sensitivity is limited to a very narrow range. In addition, it is possible to process a transducer into a parabolic shape in order to line-focus the ultrasonic beam, but it is difficult to process.
Poor practicality.

(Problems to be Solved by the Invention) As described above, acoustic lenses and concave transducers are generally used to achieve high lateral resolution, but the focusing range of narrow ultrasonic beam width and high sensitivity is limited. The problem was that it was limited to a very narrow range.

An object of the present invention is to solve the above-mentioned problems and provide an array-type ultrasonic probe with a wide focusing range.

[Structure of the invention]

(Means for Solving the Problems) First, the basis of the present invention is a method of focusing an ultrasound beam by making only the ultrasound emission surface of a rectangular transducer concave. Since only one side of the vibrator is machined into a concave surface, it is relatively easy to manufacture and high accuracy can be obtained.

The present invention is characterized in that by making the curvature of the matching layer smaller than the curvature of the concave surface of the vibrator, a thickness of the matching layer suitable for the frequency characteristics of the vibrator can be obtained. For the matching layer, heat-curable epoxy resin or the like is applied to the ultrasonic emission surface of the sensor, and a plastic film or the like of a certain thickness having a concave curvature smaller than the concave curvature of the sensor is used as the matching layer. The second matching layer is pressed against the first matching layer and then hardened to easily produce a concave matching layer.

(Function) According to the present invention, since the transducer has a wide frequency characteristic depending on the thickness of the transducer and only the ultrasonic wave emission surface is a concave surface, a wide focusing range can be obtained. In addition, since the matching layer is configured in accordance with the wide frequency characteristics of the vibrator, high sensitivity and resolution can be obtained.

(Example) Hereinafter, in FIG. 1, an example of the invention will be explained according to the drawings.
1 shows a cross-sectional view of the play deaf ultrasound probe of the present invention. The present probe has a structure in which a transducer 2 having a concave ultrasonic emission surface is attached to a packing material 1. Furthermore, the acoustic matching layer is composed of a first matching layer 3 and a second matching layer 4. The curvature of the concave surface of the second matching layer is smaller than the curvature of the vibrator, and the second matching layer is configured to fill the gap created between the vibrator and the first matching layer.

Next, we will discuss the manufacturing method and an example of the characteristics of this probe. The vibrator 2 is made of a piezoelectric ceramic substrate having a length corresponding to a predetermined number of elements and a uniform thickness, processed to have a concave surface on only one side, provided with electrodes on both sides, and then polarized. After bonding the piezoelectric ceramic substrate to the packing material 1, the piezoelectric ceramic substrate is cut into a predetermined width to obtain a plurality of vibrators. Next, a semi-cylindrical mold with a curvature smaller than that of the vibrator is prepared, and a polyester film, which will become the second matching layer, is attached to the mold. Next, a thermosetting epoxy resin that will become the first matching layer for acoustic matching with the test object is applied onto the vibrator, and a mold with polyester attached is pressed from above to form the second matching layer. cure the first
and the second matching layer are integrated. Thereafter, the mold used to fix the second matching layer is removed. Although the present array probe can be manufactured in this manner, the center frequency of the probe and the thickness and curvature of the vibrator must be carefully considered in relation to the focal length.

Further, the matching layer should also be configured to be a 1/4 wavelength matching layer that corresponds to the wide frequency characteristics of the vibrator by using materials in which the sound speeds of the first matching layer and the second matching layer are similar. is important.

Next, we will discuss the ultrasonic beam width characteristics of this probe and an array deaf probe using a conventional acoustic lens. Both probes had a center frequency of 5 MHz and a focal length of 60 to 65 mm, and the sound field characteristics in water immersion were compared. In Figure 2, the horizontal axis shows the distance between the probe and the target as water distance, and the vertical axis shows the distance on the acoustic axis of the ultrasonic radiation when the target is scanned perpendicular to the ultrasonic radiation direction. The distance of 1/2 of the maximum output is shown as the ultrasonic beam width. It is desirable that the ultrasonic beam width be as narrow as possible over a wide range, so that high lateral resolution can be obtained.

As shown in the figure, the ultrasonic beam width 21 of the array-type ultrasonic probe of the present invention covers a wider range of water than the beam width 22 of the conventional array-type ultrasonic probe using an acoustic lens. It is narrow over the distance and shows good characteristics. If we compare the water distance range where the ultrasonic beam width is 211I+ or less,
In an ultrasonic probe, an array using an acoustic lens is approximately 30
In the case of the present array-type ultrasonic probe, the number is about 551111, which is an increase of about 1.8 times.

(Effects of the Invention) By making the ultrasonic radiation surface of the transducer constituting the array-type ultrasonic probe concave, the ultrasonic beam width is narrow over a wide range, that is, the array type ultrasonic probe has the characteristics of a wide focusing area. An ultrasonic probe is obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an ultrasonic probe according to the present invention, and Fig. 2 is a cross-sectional view of an array-type ultrasonic probe using a conventional acoustic lens and an array-type ultrasonic probe according to the present invention. It is a graph showing characteristics of ultrasonic beam width. 1... Packing material, 2... Vibrator, 3... First
matching layer, 4... second matching layer, 21.
...Ultrasonic beam width characteristics of the play-type ultrasound probe of the present invention, 22...Ultrasonic beam width characteristics of the conventional array-type ultrasound probe. Agent Patent Attorney Nori Chika Yudo Kikuo Takehana

Claims (2)

[Claims] (1) In an array-type ultrasonic probe composed of a plurality of rectangular transducers, a packing material, a matching layer, etc., the ultrasonic radiation surface of the rectangular transducer has a concave shape in the long side direction. An array type ultrasonic probe characterized in that an acoustic matching layer having a concave surface having a curvature smaller than that of the concave surface of the transducer is provided on the ultrasonic emission surface of the transducer. (2) The array-type ultrasonic probe according to claim 1, wherein the acoustic matching layer has a two-layer structure made of materials with different acoustic impedances.