JPH06225875A - Ultrasonic probe - Google Patents

Abstract

PURPOSE:To provide an ultrasonic probe (1) made of composite piezoelectric plates improving workability and suitable for mass production, (2) easily attaining a high frequency, and (3) facilitating production and having a curved face. CONSTITUTION:(1) Piezoelectric ceramic and resin powder having an acoustic impedance smaller than that of the piezoelectric ceramic are mixed into mixed ceramic, and the mixed ceramic is accumulated by vapor deposition. (2) A ultrasonic probe is constituted of a substrate, the first serial electrodes made of multiple independent electrodes formed on one principal plane of the substrate, serial deposition piezoelectric plates vapor-deposited with the mixed ceramic on the serial electrodes, and the second serial electrodes formed on the serial deposition piezoelectric plates. (3) The substrate is formed into a curved face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a field of application for ultrasonic probes, and in particular, powders of piezoelectric ceramics and resin are mixed,
The present invention relates to an ultrasonic probe formed by depositing this.

[0002]

BACKGROUND OF THE INVENTION An ultrasonic probe is useful as an ultrasonic wave transmitting / receiving unit in an ultrasonic diagnostic apparatus for medical use and the like.
Piezoelectric ceramics are used as an ultrasonic transmission / reception source.
Since the acoustic impedance of piezoelectric ceramics is considerably larger than that of the human body, an acoustic matching layer having a two-layer structure is usually formed on the transmitting / receiving surface to enhance the transmitting / receiving efficiency of ultrasonic waves. For these reasons, in recent years, a composite piezoelectric plate having a low acoustic impedance has been receiving attention. Further, for early detection of minute diseased parts in the human body (living body), there is a demand for an ultrasonic probe that has a higher frequency of ultrasonic waves, has improved sensitivity by focusing, and is easy to manufacture.

[0003]

2. Description of the Related Art FIGS. 3 and 4 are views for explaining an ultrasonic probe of this type. FIG. 3 (a) is a front sectional view, FIG. 3 (b) is a side view, and FIG. It is a figure of a composite piezoelectric board. In the ultrasonic probe, the composite piezoelectric plate 2 is fixed on the backing material 1, and the composite piezoelectric plate 2n is divided into minute composite piezoelectric pieces 2n to form a linear or sector driven array type. However, electrodes for excitation are formed on both main surfaces and led out by a flexible substrate or the like (not shown). The composite piezoelectric plate 2 is obtained by vertically and horizontally cutting a piezoelectric plate 2a such as PZT (lead zirconate titanate).
Then, the cut groove is formed by filling the resin 2b (fourth
Figure). An acoustic matching layer 3 is formed on the wave transmitting / receiving surface of each composite piezoelectric piece 2n, and an acoustic lens 4 that converges in the width direction is provided.

[0004]

However, in the ultrasonic probe having the above structure, the composite piezoelectric plate 2 is formed by vertically and horizontally cutting the piezoelectric plate 2a and embedding the resin 2b therein, and then dividing it into an array type. Therefore, workability is reduced. Further, the composite piezoelectric plate 2 must be divided for each probe, which makes mass production difficult. Further, since the ultrasonic frequency is substantially inversely proportional to the thickness t of the piezoelectric plate, it can theoretically be set high indefinitely, but in reality, there is a limit due to polishing or the like. For example, when the piezoelectric plate is made of PZT, it is actually possible to achieve a frequency of about 10 MHz (thickness of about 0.1 mm), and it is difficult to achieve a higher frequency. Further, in order to maintain good characteristics, it is necessary to reduce the width w of the minute piezoelectric piece in proportion to the thickness t and maintain the w / t ratio constant. Therefore, when the piezoelectric plate is cut, it is necessary to cut with a finer pitch and with higher accuracy as the thickness becomes smaller. Further, the acoustic lens 4 is generally formed of silicon resin, but it increases the attenuation of ultrasonic waves and causes propagation loss. Therefore, for example, a piezoelectric plate curved in the width direction may be used, but in this case, it is difficult to manufacture it with high accuracy.

[0005]

An object of the present invention is, firstly, to provide an ultrasonic probe composed of a composite piezoelectric plate which has good workability and is suitable for mass production, and secondly, an ultrasonic probe which facilitates high frequency operation. It is an object of the present invention to provide a curved ultrasonic probe that facilitates manufacturing.

[0006]

The present invention relates to PVD (Phys
Chemical Vapor Deposition) or CVD (Chemical Vapor Deposition)
Focusing on the point that a piezoelectric thin film can be formed by vapor deposition such as (or Deposition), powders of piezoelectric ceramics and a resin having a lower acoustic impedance are mixed to form mixed ceramics, and the mixed ceramics are deposited by vapor deposition. That is the basic solution. Hereinafter, one embodiment of the present invention will be described together with its operation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic ultrasonic probe for explaining one embodiment of the present invention, in which FIG. 1 (a) is a front sectional view and FIG. 1 (b) is a side view. The ultrasonic probe comprises a base 5, a first row electrode 6, a composite deposition piezoelectric plate 7, a second row electrode 8 and an acoustic matching layer 9. The base 5 is made of resin or the like, and has a concave surface in the width direction of one main surface. First row electrode 6
Is composed of a plurality of electrodes that are separated and independent from each other, and are formed in alignment with the length direction of the base 5. For example, it is formed by vapor deposition with the electrode unnecessary portion being masked. The composite deposition piezoelectric plate 7 is formed on the first row electrodes 6 by PVD. That is, the mixed ceramics are deposited by vapor deposition with only the first columnar electrodes 6 exposed by the mask. The mixed ceramics is formed by mixing PZT and a resin having a lower acoustic impedance than PZT. Then, the thickness is controlled by, for example, a monitor device (not shown). The second columnar electrode 8 is formed by vapor deposition with the columnar deposited piezoelectric plate 7 exposed by a mask. The acoustic matching layer 9 has a single-layer structure, and both are arranged in rows to form PVD on the second row electrodes 8.
And the like. The electrodes on the wave transmission / reception surface side are commonly connected by, for example, a lead wire (not shown), and a filler is embedded in each gap of the row-shaped deposited piezoelectric plates and the like. And the first
After the formation of the second row electrodes 6 and 8, the polarization process is performed.

With such a structure, since particles of the mixed ceramics are scattered and deposited by PVD, a composite piezoelectric plate having an acoustic impedance smaller than that of PZT can be formed. Therefore, when the human body (living body) is used as the specific inspection body, the acoustic matching layer can have a single layer structure. Also,
By masking, the column-shaped stacked piezoelectric plates 7 are formed separately and independently, and the thickness t thereof is controlled by an electronic monitor device, so that they can be uniformly deposited in units of μm or less. Therefore, it is possible to realize a high frequency in which the ultrasonic frequency is 10 MHz or higher. Further, unlike the conventional example, it is not necessary to cut the piezoelectric plates, and the pitch p between the deposited piezoelectric plates and the width w of the deposited piezoelectric plates are determined by the mask accuracy. Therefore, the cutting process is unnecessary, workability is improved, and high-precision manufacturing is possible. Further, in this embodiment, since one main surface of the base 5 is concave, ultrasonic waves are converged without using an acoustic lens. Therefore, the ultrasonic wave is made highly sensitive without being attenuated, and the number of parts can be reduced.

[0009]

[Other Matters] In the above embodiments, the array type probe is described as an example, but it is applicable to a single plate. Further, although one main surface of the base is concave, it may be flat or convex depending on the application, and the shape is not limited. In addition, although a schematic diagram is shown and described in the embodiment, for example, regarding electrode lead-out and the like, as shown in FIG. 2, both sides of the base 5 are projected and the first row-shaped electrodes 6 are extended. , Eg flexible board (not shown)
Can be connected and led out to the outside. Further, although the second row-shaped electrodes 8 on the wave transmitting / receiving surface are commonly connected by the lead wire, they may be integrally connected at the time of vapor deposition so as not to come into contact with the first row-shaped electrodes, for example. Further, the columnar stacked piezoelectric plate 7 is provided directly on the base 5, but this is because the ultrasonic wave has a large amount of attenuation as the frequency becomes higher, and the adverse effect of the reflected wave disappears, so that the backing material is not necessary. Is. Further, although the matrix of the mixed ceramics is PZT, other piezoelectric ceramics such as lead titanate can also be applied. Further, the ultrasonic frequency may be 10 MHz or less, and in short, a structure in which an ultrasonic probe is formed by scattering and depositing mixed ceramics basically belongs to the technical scope of the present invention.

[0010]

As described above, according to the present invention, powders of piezoelectric ceramics and resin having a smaller acoustic impedance are mixed to form mixed ceramics, and the mixed ceramics are deposited by vapor deposition. As an ultrasonic probe composed of a composite piezoelectric plate suitable for mass production,
It is possible to provide an ultrasonic probe that facilitates high frequency, and thirdly, provide a curved ultrasonic probe that facilitates fabrication.

[Brief description of drawings]

FIG. 1 is a schematic ultrasonic probe diagram for explaining an embodiment of the present invention, in which FIG. 1 (a) is a front sectional view and FIG. 1 (b) is a side view.

FIG. 2 is a side view of an ultrasonic probe for explaining another embodiment of the present invention.

FIG. 3 is a diagram of an ultrasonic probe for explaining a conventional example, where FIG. 3 (a) is a front sectional view and FIG. 3 (b) is a side view.

FIG. 4 is a diagram of a composite piezoelectric plate for explaining a conventional example.

[Explanation of symbols]

5 bases, 6 and 8 row electrodes, 7 row deposited piezoelectric plates, 9
Acoustic matching layer

Claims (3)

[Claims] 1. An ultrasonic probe characterized by being formed by mixing powders of piezoelectric ceramics and a resin having a lower acoustic impedance than the ceramics to prepare mixed ceramics, and depositing the mixed ceramics by vapor deposition. 2. The mixed ceramics according to claim 1, wherein a base, a first row-shaped electrode formed on one main surface of the base and formed of a plurality of independent electrodes, and the row-shaped electrode are provided on the first row-shaped electrode. An array-type ultrasonic probe for high frequency, comprising: a column-shaped deposited piezoelectric plate formed by vapor-depositing and a second column-shaped electrode formed on the column-shaped deposited piezoelectric plate. . 3. The ultrasonic probe for high frequencies, wherein the base of claim 2 is a curved surface.