JPH0520079Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an improvement of a phase array transducer used in electronic sector scan ultrasonic echo tomography devices and the like.

[Conventional technology]

As shown in Fig. 1, a conventional phased array ultrasonic transducer consists of n piezoelectric elements 1 such as PZT, each of which has a rectangular shape, arranged in parallel. By driving with an appropriate phase through the element 2, the composite wavefront A of the radiated ultrasonic waves is made to proceed at an arbitrary angle in the θ direction. In this case, the combined intensity of the ultrasonic waves in the direction of travel is a function of θ. In the figure, 3 and 4 are drive electrodes.

[Problem that the invention attempts to solve]

By the way, each piezoelectric element generally has directionality.
That is, as shown in FIG. 2, the ultrasonic wave has an intensity distribution in the θ direction. Therefore, there is a drawback that the output and input of the combined ultrasonic beam are insufficient in the direction where the deflection angle θ is large.

For this reason, in electronic sector scan ultrasonic echo tomography devices and the like, as the deflection angle θ increases, driving power is increased and the degree of amplification of the received echo signal is increased.

However, there is a limit to the increase in voltage, and when the ultrasonic attenuation in a medium such as the human body is large, increasing the amplification degree also amplifies noise, which is disadvantageous.

The present invention is intended to solve these problems, and aims to provide a phase array transducer in which the dependence of the radiated ultrasound intensity on the deflection angle can be arbitrarily set.

The configuration of the present invention is as follows. That is, a piezoelectric element made of an organic piezoelectric film for transmitting and receiving ultrasonic waves is provided with a plurality of electrodes, and these electrodes transmit and receive waves with a phase difference between them. In the phased array transducer for deflecting an ultrasound beam, the electrode is made of a metal material having a cylindrical shape, and at least an arc-shaped organic piezoelectric film is formed in contact with the electrode. This is a phased array oscillator with special features.

〔Example〕

Next, embodiments of the present invention will be described with reference to FIGS. 3 to 8.

In this invention, the transmitting and receiving surfaces of the piezoelectric element are made curved rather than flat, so that the deflection angle dependence of the emitted ultrasonic intensity can be set arbitrarily. Explain.

FIG. 3 shows a first embodiment.

In the case of this example, a plurality of drive electrodes 12 having a circular cross section, such as metal wires having an appropriate diameter, are mounted on the backing member 11.
is disposed thereon, covered with an organic piezoelectric film 14 on the outer surface of which a conductive film (external electrode) 13 is formed by aluminum vapor deposition or the like, and fixed by adhesive or the like to form a vibrator main body. The organic piezoelectric film 14 is made of polyvinylidene fluoride (PVDF) or the like. In this case, each drive electrode 12 and a conductive film 13 (generally grounded), which is an external electrode facing it, constitute an element, and the transmitter and receiver surfaces of the element are curved with appropriate curvatures. , the directivity of each element on the transmitting and receiving surfaces becomes nearly omnidirectional, and the ultrasonic intensity distribution in the θ direction becomes uniform, as shown by the arrow line in the figure in the direction perpendicular to the drive electrode 12. When performing an ultrasonic sector scan, the dependence of the radiated ultrasonic intensity on the deflection angle can be improved. This deflection angle dependence can be arbitrarily set by appropriately selecting the diameter of the drive electrode 12.

Note that an arbitrary matching layer protective layer, an ultrasonic lens, a prism, etc. may be added to the outside of the conductive film 13, and a material with good ultrasonic absorption characteristics may be used as the backing member 11.

However, in this case, the ultrasonic lens has a drive electrode 1
This means something that focuses ultrasonic waves in two directions, and such something is well known.

FIG. 4 shows a second embodiment.

In the case of this example, an organic piezoelectric film 22 such as PVDF is provided in a concentric cylindrical shape around a driving electrode 21 having a circular cross section made of metal wire or the like with an appropriate diameter, and the outside thereof is coated with metal plating, vacuum evaporation, conductive paint coating, etc. Basically, a conductive film (external electrode) 23 is formed thereon, and this wire-like structure 24 is disposed on a backing member 25 to constitute a vibrator. In this case, each drive electrode 21, the piezoelectric film 22, and the conductive film 23 surrounding it constitute an element, and it is possible to achieve the same effect as the previous example. Note that a matching layer protective layer, an ultrasonic lens, a prism, etc. may be added to the outside of the conductive film 23, and a material with good ultrasonic absorption characteristics may be used as the backing member 25.

The material for the wire-like structure (one that does not form a conductive film) can be easily manufactured using the same manufacturing method as for ordinary wires, but in this case, while drawing the drive electrode material,
When forming a PVDF coating, by restricting the temperature and applying tension, the molecular arrangement can be aligned, and the PVDF
It is possible to form and polarize the PVDF layer at an appropriate temperature while applying a voltage between the external die for coating formation and the drive electrode material.

Further, the material for the wire-like structure can be produced by the procedure shown in FIG. i.e. PVDF
A conductive resin 27 serving as a driving electrode is placed at the end of the plate 26.
It can be manufactured by setting the conductive resin 27 and rolling it in from the conductive resin 27 side.

Using the wire-like structure formed by forming a conductive film on the surface of the material produced as described above, a phased array oscillator of the type shown in Fig. 4 is obtained by the procedure shown in Fig. 6 or 7. be able to.

In the case of FIG. 6, as shown in FIG.
4 is wound a plurality of times and then cut at the position of the chain line to obtain the vibrator main body 29 having the shape shown in FIG. 6b.

In the case of FIG. 7, as shown in FIG. 7a, the wire-like structure 2
4 is wound several times to form a film of the backing member material 31 on its outer periphery, and after removing the mold release core 30, this is cut at the chain line position to form the shape shown in FIG. 7b. A vibrator body 29' can be obtained. In this case, the wire-like structure 24 is the eighth
As shown in the figure, since it is concavely curved in the direction perpendicular to the juxtaposed direction, in addition to the above-mentioned effect, the transmitted ultrasonic beam 31 is focused on the curved shape of the wire-like structure 24 as shown in the figure. It is possible to achieve the effect of narrowing down near O.

[Effect of idea]

As described above, according to the present invention, it is possible to arbitrarily set the dependence of the radiated ultrasound intensity on the deflection angle.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional phase array oscillator, Figure 2
The figure is an explanatory diagram showing the radiated ultrasound intensity distribution of the same element.
FIG. 3 is a front view of the main part showing the first embodiment of the phase array resonator according to the present invention, FIG. 4 is a front view of the main part showing the second embodiment of the same, and FIG. 6 and 7 are diagrams showing the procedure for forming the electric wire-like structure shown in FIG. 4 and FIG. 8, respectively.
The figure is an explanatory diagram of the ultrasonic beam narrowing effect by the transducer produced by the procedure shown in Fig. 7. In the figure, 2 is a delay element, 11 and 25 are backing members, 12 and 21
13, 23 are conductive films, 14, 22 are piezoelectric films, 24 is a wire-like structure, and 29, 29' are vibrator bodies.

Claims (1)

[Claims for Utility Model Registration] A piezoelectric element made of an organic piezoelectric film for transmitting and receiving ultrasonic waves is provided with a plurality of electrodes, and each of these electrodes has a phase difference for transmitting and receiving,
In a phase array transducer that deflects a synthetic ultrasound beam formed by an organic piezoelectric film, the electrode is made of a metal material having a cylindrical shape, and at least the radiation surface is an arc-shaped organic piezoelectric film. A phase array vibrator, characterized in that it is formed in contact with the electrode.