JPH07274293A - Array type ultrasonic probe - Google Patents

Abstract

PURPOSE:To provide an array type probe in which an acoustic lens is not required, the sensitivity is improved and the resolution in the minor axis direction is easily enhanced. CONSTITUTION:In the array type ultrasonic wave probe formed by arranging plural paper-tablet piezoelectric elements 2 in the broadwise direction, each piezoelectric element 2 is made up of plural elements split in the minor axis direction, and delay elements 1 whose delay is smaller from the middle position toward elements at both ends are connected in common and built in the probe main body. The piezoelectric element is made up of three elements split in the minor axis direction and a delay element is connected only to the element in the middle.

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 (referred to as an array type probe), and more particularly to an array type probe which does not require an acoustic lens.

[0002]

BACKGROUND OF THE INVENTION It is useful as an ultrasonic wave transmitter / receiver in an array type probe, for example, a medical ultrasonic diagnostic apparatus. Among these, for example, there is an electronic scanning method in which strip-shaped piezoelectric vibrators having a minute width are arranged in the width direction (long axis direction) and linear or sector drive is performed in the long axis direction. Then, generally, in the length direction (short axis direction) of the piezoelectric element, an acoustic lens is covered so that ultrasonic waves are also converged in the length direction (short axis direction) of the piezoelectric element to improve the resolution in the same direction. I have to.

[0003]

2. Description of the Related Art FIG. 6 is a diagram of an ultrasonic probe for explaining a conventional example of this kind. FIG. 6 (a) is a front sectional view and FIG. 6 (b) is a side sectional view. The ultrasonic probe has P on the backing material 1.
The strip-shaped piezoelectric elements 2 made of ZT (lead zirconate titanate) are arranged in the width direction. Electrodes 3 (ab) are provided on both main surfaces of the piezoelectric element 2. An acoustic matching layer 4 is provided on the front surface of the piezoelectric element 2 so as to match the acoustic impedance with the living body and improve the ultrasonic wave propagation efficiency. Further, it is formed by attaching a convex acoustic lens 5 in the minor axis direction. Then, it is enclosed in a container (not shown). In addition, these are shown by a dotted line frame, and the probe main body 6 is formed. However, from each piezoelectric element 2, a lead wire 7 that is individually connected to the electrode 3b on the rear surface and a lead wire (not shown) that commonly connects the electrode 3a on the front surface are led out.

In such a device, as shown in FIG. 7, a high voltage pulse P is applied to each piezoelectric element 2 from the diagnostic device side 8 through each delay circuit 9. Then, by sequentially controlling the delay time θ ₍₁ to ₅₎ of the delay circuit 9, the ultrasonic waves are sent out in a fan shape in the long axis direction. That is, the wavefront W of the ultrasonic wave is changed from AA to BB with time, the ultrasonic wave is advanced in the direction orthogonal to the wavefront, and the sector is driven in the long axis direction. Then, in the short axis direction, the acoustic lens 5 converges the ultrasonic waves, so that the resolution in the same direction can be increased. Reference numeral 10 in the drawing is a cable connecting the probe body 6 and the diagnostic device side 8.

[0005]

However, in the above-described structure, since the acoustic lens 5 is used, there is a problem that attenuation occurs during propagation of ultrasonic waves and the transmission / reception gain (sensitivity) is lowered. From such a fact, for example, m piezoelectric elements 2 are divided into n also in the minor axis direction, and lead wires are derived for each.
It has been attempted to electronically converge ultrasonic waves in the same direction by a delay pulse from the diagnostic device side 8. However, in this case, m × n lead wires are led out from the probe main body 6 to the diagnostic device side 8 by the cable 10, so that the cable diameter is made large and the handling thereof is troublesome. Also,
On the side of the diagnostic device 8, a total of n × m delay circuits must be connected to the lead wires to control the delay amount for converging the short-axis direction along with the sector drive, which causes a problem of a complicated mechanism. .

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an array type probe which can improve sensitivity and can easily enhance resolution in the short axis direction.

[0007]

According to the present invention, a strip-shaped piezoelectric element is formed of a plurality of elements divided in a length direction (short axis direction) thereof, and a delay amount increases from a central portion to elements at both ends. The solution is that the delay elements are connected and commonly connected, and the delay elements are built in the probe body. Hereinafter, one embodiment of the present invention will be described together with its operation.

FIG. 1 is a schematic view of an array type probe for explaining an embodiment of the present invention, and FIG. 2 is a sectional view in the minor axis direction. In FIG. 3, the same parts as those of the prior art example are given the same numbers, and the description thereof will be simplified. As described above, the array type probe has the piezoelectric elements 2 arranged in the longitudinal direction on the backing material 1 and the acoustic matching layer 4 provided on the front surface (see FIG. 6). Further, in this embodiment, each piezoelectric element 2 is composed of a plurality of elements divided in the minor axis direction. For example, it is divided into three elements 2 (abc). The delay element 11 (abc) is connected to each element 2 (abc) through the lead wire 7, and is also commonly connected to each piezoelectric element 2. The delay amount φ _{(1, 2, 3)} of each delay element 11 becomes smaller toward the both ends with φ ₂ at the center being the maximum (where φ ₁ = φ ₃ ). In short, the center is maximum and symmetrical. In addition, these delay elements 11
(Abc) is mounted in the probe main body 6.

In such a device, as described above, the high voltage pulse P is applied from the diagnostic device side 8 to each piezoelectric element 2 through the delay circuit 9, and the sector drive is performed in the long axis direction. Then, in the short axis direction, the high-voltage pulse P is applied through the delay element 11 (abc) having the maximum delay amount in the center. Therefore, the wavefronts of the ultrasonic waves are OA and OB, and the ultrasonic waves travel toward the center as shown in FIG. 3 (a), so that the intensity distribution of the ultrasonic waves becomes maximum at the central portion. The same figure (b). " In other words, it converges in the same way as when an acoustic lens is added. In addition, the convergence part (focal length)
Can vary depending on the amount of delay.

Therefore, in such an ultrasonic probe, the ultrasonic waves can be converged in the short axis direction without using a conventional acoustic lens, so that the resolution can be improved and the propagation loss can be prevented. The sensitivity can be increased. Then, the delay element 11 is built in the probe main body 7 and connected in common for each piezoelectric element 2 and is led out to the outside. Therefore, the number of lead wires may be the same as the conventional one, and it is necessary to increase the cable diameter. There is no. Therefore, it is easy to handle.
In addition, the minor axis direction is controlled by a fixed amount of delay element inside the probe main body, and the major axis direction is controlled by a delay circuit on the diagnostic device side as in the conventional case, independently of each other. Therefore, the sector can be easily driven in the major axis direction and the minor axis direction can be converged to the central portion without complicating the mechanism.

[0011]

[Other Matters] In the above embodiment, the piezoelectric element 2 was divided into the respective elements 2 (abc), but the front surface of the piezoelectric element 2 is divided into the common electrode 3a (or the divided portion) as shown in FIG. The same effect can be expected by providing the divided electrode 12 (abc) on the rear surface and connecting the delay element 10 (abc) to the divided electrode 12 as the electrode). That is, in this case, the common electrode 3a and the divided electrodes (abc) on both main surfaces
The opposing portion of 6 is basically the element 2 (ab
Operates corresponding to c). Further, in the above-mentioned example, since the delay element 10 (abc) is connected to each element 2 (abc), basically, when n piezoelectric elements are arranged and the short axis direction is divided into m, n × m. This requires delay elements. So, for example, dividing the minor axis direction into three,
If the delay element is connected only to the central element 2b and the elements at both ends are simply connected to only the lead wire 7 and are commonly connected, only n delay elements 10 are provided. Also in this case, the ultrasonic waves can be converged to the center as in the case described with reference to FIG. Therefore, the number of delay elements 10 can be minimized, which is extremely practical. Further, the drive system has been described as a sector, but may be linear, that is, the piezoelectric element 2 is electrically divided into a plurality of elements, and the delay amount is gradually reduced from the central portion to both end portions. It suffices that a fixed amount of delay element is connected, and an ultrasonic probe based on such an idea belongs to the technical scope of the present invention even if there is only one piezoelectric element.

[0012]

According to the present invention, a strip-shaped piezoelectric element is formed of a plurality of elements divided in the direction of the short axis, and a delay element whose delay amount decreases from the central portion to the elements at both ends is connected. Since they are commonly connected, it is possible to provide an array type probe that can improve the sensitivity and the resolution in the short axis direction.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention, and FIG. 1 (a) is a schematic configuration diagram of an ultrasonic probe. .

FIG. 2 is a sectional view (short axis direction) of an ultrasonic probe for explaining an embodiment of the present invention.

FIG. 3 (a) and FIG. 3 (b) are views for explaining the operation of one embodiment of the present invention.

FIG. 4 is a cross-sectional view (short axis direction) of an ultrasonic probe for explaining another embodiment of the present invention.

FIG. 5 is a sectional view (short axis direction) of an ultrasonic probe for explaining another embodiment of the present invention.

FIG. 6 is a view for explaining a conventional example, FIG. 6A is a front sectional view (long axis direction) of an ultrasonic probe, and FIG. 6B is a side sectional view (short axis direction). .

FIG. 7 is a diagram illustrating sector drive of an ultrasonic probe for explaining a conventional example.

[Explanation of symbols]

1 backing material, 2 piezoelectric element, 3 electrode, 4 acoustic matching layer, 5 acoustic lens, 6 probe body, 7 lead wire, 8 diagnostic device side, 9 delay circuit, 10 cable,
11 delay elements, 12 split electrodes.

Claims (2)

[Claims] 1. An array-type ultrasonic probe comprising a plurality of strip-shaped piezoelectric elements arranged in the width direction of the piezoelectric element, wherein the piezoelectric element is formed of a plurality of elements divided in the length direction thereof. An ultrasonic probe characterized in that a delay element having a smaller delay amount is connected to a common element by connecting from a portion to an element at both ends, and is incorporated in a probe body. 2. The piezoelectric element is divided into three parts in a minor axis direction.
The ultrasonic probe according to claim 1, wherein the ultrasonic probe is composed of individual elements, and the delay element is connected only to the central element.