JPH08223697A - Array type ultrasonic probe - Google Patents

Abstract

PURPOSE: To eliminate the undesired ultrasonic waves generated at both ends of an acoustic lens and to obtain the excellent images by providing an ultrasonic wave shield at each of both ends of the acoustic lens having a curvature part that is shorter than the length of a piezoelectric element. CONSTITUTION: The double acoustic junction layers 3a and 3b are put side by side on a packing member 1 and in the longer axis direction of a pizoelectric element 2. Additionally, a convex acoustic lens 4 is attached in the shorter axis direction of the element 2. The length La of a lens member 4a of the lens 4 is set shorter than the length Lb of the element 2, and the holding legs 4c are provided at both ends of the lens 4 via a flat member 4b. Then a copper foil, e.g., a reflecting member, etc., that functions as an ultrasonic wave shield 9 is provided on the member 45. In such a constitution, the ultrasonic waves radiated at both ends of the element 2 are reflected on the shield 9 and never reach a testee body. Then these reflected waves are transmitted from the parts near the surface of the element 2 and therefore clearly distinguished from the reflected waves received from the testee body. As a result, the noise components are reduced and the picture quality is improved. Then the diagnostic accuracy is also improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an application field of an array type ultrasonic probe having an acoustic lens (hereinafter referred to as an array type probe), and particularly an array type probe which shields unnecessary ultrasonic waves. Regarding

[0002]

BACKGROUND OF THE INVENTION Array type probes are useful as ultrasonic wave transmitters / receivers in, for example, medical ultrasonic diagnostic equipment. For example, strip-shaped piezoelectric elements having a minute width are arranged in the width direction (long axis direction), and linear or sector drive is performed in the same direction. In such a device, an acoustic lens is generally provided in the length direction (short axis direction) of the piezoelectric element to improve the resolution.

[0003]

2. Description of the Related Art FIG. 2 is a view of an array type probe for explaining a conventional example of this kind. FIG. 2 (a) is a front sectional view and FIG. 2 (b) is a side sectional view. The array type probe has P on the backing material 1.
The strip-shaped piezoelectric elements 2 made of ZT (lead zirconate titanate) or the like are arranged in the major axis direction. Electrodes are provided on both main surfaces, and a filler is embedded between the grooves (not shown). And
On the front surface of the piezoelectric element 2, a two-layer acoustic matching layer 3 (ab) is provided for measuring acoustic impedance matching with a detected body (living body or the like) and improving ultrasonic wave propagation efficiency. Further, the acoustic lens 4 is attached in the minor axis direction. However, when the sound velocity is slower than that of the object to be detected, it is convex, and when it is faster, it is concave (not shown).

[0004] The acoustic lens 4 is basically when bonded to match the length L _a of the curvature portion (lens portion) 4a to L _b of the piezoelectric element 2 (FIG. 3), the smallest thickness t The propagation loss of ultrasonic waves can be minimized. However, if the centers (AA ′, BB ′) of the acoustic lens 4 and the piezoelectric element 2 deviate from the manufacturing point of error or positioning, etc. (fourth
In the figure), the substantial radiation area S of the ultrasonic wave is reduced, and the convergence direction U is inclined from the center line, so that the specifications cannot be achieved. From this, for example, the length L _b of the piezoelectric element 2 is made larger than L _{a of the} lens portion 4a. Then, "flat front portion 2b" in which flat portions 4b are provided on both end sides and holding legs 4c are further provided. In this way, the L _a <L _b, the center of the acoustic lens 4 is also shifted from that of the piezoelectric element 2, to reliably converge the ultrasound on the center line of the acoustic lens 4. Further, the holding legs 4c prevent the acoustic lens 4 from being disengaged or displaced due to a pressing force during use. In addition,
When the lens portion 4a has the same curvature and is larger than the piezoelectric element 2 (FIG. 5), the thickness t becomes large. Also,
When the centers of the two are deviated, the direction of convergence of ultrasonic waves is inclined from the center, as described above.

In such a structure, each piezoelectric element 2 has
A high voltage pulse P is applied through a delay circuit (not shown),
Sector drive is performed in the long axis direction. Then, in the minor axis direction, the resolution can be improved by converging the ultrasonic waves with the acoustic lens 4. In addition, reference numeral 5 in the drawing
Is a base, 6 is a flexible substrate, 7 is a fixing resin,
8 is a case. Further, lead wires for commonly connecting the front side of the piezoelectric element 2 are omitted.

[0006]

However, in the above-mentioned configuration, as described above, the acoustic lens 4 is
The lens portion 4a is smaller than the length of the piezoelectric element 2. Therefore, the ultrasonic wave from the central region of the piezoelectric element 2 passes through the lens portion 4a and is converged. However, it has been recently revealed that ultrasonic waves emitted from both ends of the piezoelectric element 2 have an adverse effect along with the increase in precision. That is, the ultrasonic waves from both ends pass through the flat portion 4b of the acoustic lens 4 and go straight, and are reflected and received by an interface region such as a diseased part in the same region and are received. As a result, there is a problem that the reflected wave in the original convergence region becomes a noise component, disturbs the image, and deteriorates the diagnostic accuracy.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic probe which eliminates unnecessary ultrasonic waves from both ends of an acoustic lens and obtains a good image.

[0008]

SOLUTION: The basic solution means of the present invention is to provide ultrasonic shields on both ends of an acoustic lens having a curvature portion set to be shorter than the length of a piezoelectric element. An embodiment of the present invention will be described below.

[0009]

1 is a side sectional view of an ultrasonic probe for explaining an embodiment of the present invention. The same parts as those in the prior art example are designated by the same reference numerals, and the description thereof will be simplified. In the array type probe, similarly to the above, the piezoelectric elements 2 are arranged in the long axis direction on the backing material 1, two acoustic matching layers 3 (ab) are provided, and the convex acoustic lens 4 is provided with the short axis. It is formed by attaching in the direction. The acoustic lens 4 has a length L of the lens portion 4a.
_a is made smaller than L _b of the piezoelectric element 2 and flat portions 4 are provided on both end sides.
Holding legs 4c are provided with b interposed. Then, the flat portion 4b is provided with, for example, a copper foil serving as a reflecting material, which functions as the ultrasonic shield 9.

With such a configuration, the ultrasonic waves emitted from both ends of the piezoelectric element 2 are reflected by the ultrasonic shield 9 and are not emitted to the object to be detected. Since the reflected waves from both ends are reflected from the vicinity of the surface of the piezoelectric element 2, they are clearly distinguished from the reflected waves from the object to be detected, and the resolution is not affected by image processing or the like. Therefore, only the signal transmitted / received from the central region of the piezoelectric element 2 via the lens portion 4b can be processed, so that the noise component can be reduced, the image can be improved, and the diagnostic accuracy can be improved. Further, incidentally, by setting the length L _a of the lens portion freely, it is possible to control the substantial opening area and improve the production.

[0011]

[Other Matters] In the above-described embodiment, the ultrasonic shield 9 achieves its function as a reflector, but it may be a sound absorber having a large attenuation of ultrasonic waves. Further, although the ultrasonic shield 9 is applied on the flat portion 4b of the acoustic lens 4, it may be on the lower side or embedded in the flat portion, and further, for example, a leg including the lens portion 4a and the flat portion 4b. You may integrally join with the part 4c as a separate body. Further, although the flat portions 4b are provided on both end sides of the lens portion 4c, they are not necessarily required to be literally flat and may be curved surfaces or rough surfaces. Further, although the sector drive has been described, linear drive may be used. In short, an acoustic lens is attached in the short axis direction of an array type in which piezoelectric elements (including division) are arranged, and a substantial radiation area and What shields both end sides other than the lens portion 4a is included in the technical scope of the present invention. Although the acoustic lens has a convex shape, as a matter of course, it may have a concave shape because of the relationship with the speed of sound as described above.

[0012]

According to the present invention, since the ultrasonic shields are provided on both end sides of the acoustic lens having the curvature portion set to be shorter than the length of the piezoelectric element, unnecessary ultrasonic waves from both end sides of the lens portion are eliminated. It is possible to provide an ultrasonic probe that eliminates and obtains a good image.

[Brief description of drawings]

FIG. 1 is a side sectional view of an ultrasonic probe for explaining an embodiment of the present invention.

FIG. 2 is a diagram of an ultrasonic probe for explaining a conventional example, where FIG. 2 (a) is a front sectional view and FIG. 2 (b) is a side sectional view.

FIG. 3 is a partial side sectional view of an ultrasonic probe for explaining a conventional example.

FIG. 4 is a partial side sectional view of an ultrasonic probe for explaining a conventional example.

FIG. 5 is a partial side sectional view of an ultrasonic probe for explaining a conventional example.

[Explanation of symbols]

1 backing material, 2 piezoelectric element, 3 acoustic matching layer, 4
Acoustic lens, 5 bases, 6 flexible, 7 fixing resin, 8 case, 9 ultrasonic shield.

Claims (1)

[Claims] 1. An array in which a plurality of piezoelectric elements are arranged in the width direction, an acoustic lens having a curvature portion in the length direction of the piezoelectric elements and leg portions on both end sides is provided on the piezoelectric element group. The ultrasonic probe of the type, wherein a curvature portion of the acoustic lens is shorter than a length of the piezoelectric element, and ultrasonic shields are provided on both end sides.