JP2642068B2 - Ultrasonic probe manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ultrasonic probe for transmitting and receiving ultrasonic waves in an ultrasonic diagnostic apparatus.

[0002]

2. Description of the Related Art Medical techniques for obtaining an ultrasonic tomographic image of a human body using ultrasonic waves are known. FIG. 2 is a sectional view of an ultrasonic probe used in a mechanical scan type ultrasonic diagnostic apparatus. Referring to FIG. 1, reference numeral 11 denotes a piezoelectric vibrator. Electrodes (not shown) are provided on the front and back of the piezoelectric vibrator 11, an acoustic matching layer 12 is provided on one electrode side, and a damping 13 layer is provided on the other electrode side. One factor that affects the performance of such an ultrasonic probe is the characteristic of the acoustic impedance of the acoustic matching layer 12. Conventionally, in order to obtain an appropriate acoustic impedance of the acoustic matching layer 12, chalcogenite glass, for example, arsenic sulphide selenide glass, has been used. However, this material has poor stability and is toxic to humans. Currently not used. In order to obtain an appropriate acoustic impedance of the acoustic matching layer instead, FIG.
A two-layer acoustic matching layer as shown in a perspective view of FIG. In the figure, reference numeral 12a denotes a first acoustic matching layer formed of quartz glass or flint glass and provided in contact with one surface of the piezoelectric vibrator 11, and 12b denotes a second acoustic matching layer formed of epoxy resin. is there. And the second
A silicon lens 14 for focusing an ultrasonic beam is provided on the acoustic matching layer, and a piezoelectric vibrator 11 including a first acoustic matching layer 12a and a second acoustic matching layer 12b corresponding to an ultrasonic wavelength to be used is provided. Notches (not shown) are provided at predetermined regular intervals to improve the directivity characteristics and constitute an ultrasonic probe. By configuring the acoustic matching layer in a two-layer structure formed of an appropriate material, the acoustic impedance can be matched to the acoustic impedance of the subject,
High sensitivity and wide band characteristics can be obtained. When using an ultrasonic probe having such a configuration as an endoscope, it is necessary to insert the probe into the body. In order to increase the wavelength, it is necessary to shorten the wavelength. For this reason, the required interval of cuts provided in the piezoelectric vibrator 11 including the acoustic matching layers 12a and 12b becomes extremely short, and naturally, the cut width also needs to be narrowed. For this reason, a diamond cutter having a very thin blade is usually used for making this cut.

[0003]

However, if the acoustic matching layer is made of quartz glass or flint glass, these materials are brittle, so that cracks are likely to be formed when making the above-mentioned cuts. There is a problem that the piezoelectric vibrator provided in contact with the probe is broken and the characteristics of the wave probe are remarkably deteriorated. Further, there is also a problem in that preferable characteristics cannot be obtained unless selection of a material constituting the plurality of acoustic matching layers and their combination are not appropriate.

The present invention has been made to solve the above-described problems, and has a high sensitivity and a wide bandwidth.
Moreover, it is an object of the present invention to provide a method of manufacturing an ultrasonic probe having excellent workability.

[0005]

SUMMARY OF THE INVENTION An ultrasonic probe according to the present invention
The main features of the manufacturing method of the present invention are that an acoustic matching layer forming step of forming at least one layer of an acoustic matching layer on one surface of the piezoelectric vibrator with free-cutting crystallized glass and a damping layer on the other surface of the piezoelectric vibrator. Layer forming process and damping for forming
After completing the layer formation process, the piezoelectric vibrator and acoustic matching layer
Step of forming a gapped portion by making a cut with a predetermined width
Based on the manufacturing method with
It has a thickness of 1/4 of the wavelength of the sound wave and a predetermined acoustic impedance.
First sound made of crystallized glass with free-cutting dance
Forming a matching layer and applying an ultrasonic wave on the first acoustic matching layer;
Thickness of 1/4 of the wavelength and smaller than the first acoustic matching layer
Second sound made of material having low acoustic impedance
A process for forming a matching layer is also provided. Also, the second acoustic matching layer
The acoustic impedance smaller than the first acoustic matching layer in the forming process
Use epoxy resin as a material with
Can also be. In addition, for piezoelectric vibrator and acoustic matching layer
In the gap portion forming step, d <λ / ｛1+ | sin (θ /
2) Form gaps at equal intervals according to the conditions of |｝
Also features. Further, the present invention provides a gap type
After completion of the formation process, an acoustic lens part is formed on the acoustic matching layer
It is also characterized by including a step of performing.

[0006]

By forming at least one layer of the acoustic matching layer on one surface of the piezoelectric vibrator with crystallizable glass having good workability and less crack progression, the accuracy of the step of forming the cut is improved. In addition to increasing the height, the piezoelectric vibrator in contact with the acoustic matching layer is prevented from being damaged due to this cutting step, and the other acoustic matching layer is formed of epoxy resin, and is formed with one of the free-cutting crystallized glass. The acoustic characteristics of the ultrasonic probe can be improved by the combination.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an ultrasonic probe according to the manufacturing method of this embodiment. In the figure, 1 indicates that the material is P
ZT, acoustic impedance Z _P is 33 × 10 ⁶ Kg
The piezoelectric vibrator has an m ⁻² sec ⁻¹ , and in one step on one plate surface of the piezoelectric vibrator 1, the material is a free-cutting crystallized glass, and the acoustic impedance Z ₁ is 14.4 ×. 10 ⁶ Kg m
The first acoustic matching layer 2 formed at ^-2 sec ^{-1 and} having a thickness of ４ of the ultrasonic wavelength λ is provided. Further, in the second step, the material is made of epoxy resin on the first acoustic matching layer 2,
Acoustic impedance Z ₂ is 3.14 × 10 ⁶ Kg m ^-2 sec
^-1 and a thickness of 1/4 of the ultrasonic wavelength λ.
An acoustic matching layer 3 is provided. In the third step, a damping layer 4 formed by dispersing tungsten powder or the like in epoxy resin is provided on the other plate surface of the piezoelectric vibrator 1.
Then, in the fourth step, the piezoelectric vibrator 1, the first acoustic matching layer 2 and the second acoustic matching layer 3 are formed using a diamond cutter by the following equation d <λ / (1+ | sin (θ / 2) |), where d: The gap 5 is formed by cutting at equal intervals satisfying the following conditions: the division center interval of the transducer, λ: wavelength of ultrasonic wave, θ: scanning angle. In the next fifth step, a silicon lens 6 for focusing the ultrasonic beam is formed on the upper surface of the second acoustic matching layer 3,
The main part of the ultrasonic probe of the embodiment is completed. Table 1 shows the characteristics of each material used in this example.

[0008]

[Table 1]

Next, the free-cutting crystallized glass used in this embodiment will be described in detail. This free-cutting crystallized glass is composed of SiO ₂ (46 wt%), Al ₂ O ₃ (16 wt%).
%), Mg O (17wt% ), K 2 O (10wt%), F
(4% by weight) and B ₂ O ₃ (7% by weight), and a mixture of these was melted and put into a mold and cooled to obtain a desired shape.
It is obtained by heating and crystallizing it, and has a structure in which microcrystals of synthetic mica are randomly grown uniformly in borosilicate glass as a base material.

As described above, the free-cutting crystallized glass has a structure in which microcrystals of synthetic mica are randomly dispersed in the base material borosilicate glass. When the notch is provided in the first acoustic matching layer 2 constituted by
Since the crack is prevented by the synthetic mica crystal and does not progress to the inside and is limited to the cut portion, the piezoelectric vibrator 1 provided in contact with the crack may be damaged by the progress of the crack in the first acoustic matching layer 2. Absent. In addition, since the crystallized glass having a free-cutting property is a cutting mechanism having a good cutting workability capable of cutting while generating powdery chips, the gap size of the gap 5 and the cutting interval of the piezoelectric vibrator 1 are smaller than those of conventional materials. d can be made accurate, and the characteristics as an ultrasonic probe can be improved.

The preferred acoustic characteristics of the two-layered acoustic matching layer are as follows: the acoustic impedance of the subject is Z _OT ; the acoustic impedance of the piezoelectric vibrator is Z _P ; the acoustic impedance of the first acoustic matching layer is Z ₁ ; (2) Assuming that the acoustic impedance of the acoustic matching layer is Z ₂ , the relationship of Z ₁ / Z ₂ = (Z _P / Z _OT ) ^1/2 is satisfied. By satisfying this expression, high-sensitivity characteristics can be obtained in a wide band. According to this embodiment, Z ₁ = 14.4 × 10 ⁶ Kg m ^-2 sec ^-1 Z ₂ = 3.14 × 10 ⁶ Kg m is _{^{-2 sec -1 Z P = 33 ×}} 10 6 Kg m -2 sec -1, when the ^{_{Z P = 1.5 × 10 6 Kg}} m -2 sec -1, Z 1 / Z ₂ = 4.59, and one of (Z _P / Z _OT )
The value almost matches the value of ^1/2 = 4.69, and an almost ideal ultrasonic probe can be obtained. This is a result of selecting free-cutting crystallized glass and epoxy resin as materials for the first acoustic matching layer 2 and the second acoustic matching layer 3 and combining them.

It should be noted that the present invention is not limited to the above-described embodiment, but can be modified and implemented without changing the gist. In the above embodiment, the acoustic matching layer has a two-layer structure. For example, even in the case of a three-layer structure or more, the use of a free-cutting crystallized glass for the acoustic matching layer in contact with the vibrator has been described in the embodiments. Can be implemented effectively.

[0013]

As described above, according to the present invention, it is possible to provide a method of manufacturing an ultrasonic probe having high sensitivity, a wide bandwidth, and excellent workability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an ultrasonic probe manufactured by a process according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional ultrasonic probe.

FIG. 3 is a perspective view of another conventional ultrasonic probe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator, 2 ... 1st acoustic matching layer, 3 ... 2nd acoustic matching layer, 4 ... Damping layer, 5 ... Gap, 6 ... Silicon lens.

Claims (6)

(57) [Claims] 1. An acoustic matching layer forming step of forming at least one acoustic matching layer of free-cutting crystallized glass on one surface of a piezoelectric vibrator, and forming a damping layer on the other surface of the piezoelectric vibrator. A damping layer forming step, and after the damping layer forming step is completed, a gap section forming step of forming a gap section by cutting the piezoelectric vibrator and the acoustic matching layer with a predetermined width. A method for manufacturing an ultrasonic probe, comprising: 2. The step of forming an acoustic matching layer comprises forming a first acoustic matching layer made of crystallizable glass having a thickness of one-fourth of an ultrasonic wave and having a predetermined acoustic impedance. a first acoustic matching layer forming step, on the first acoustic matching layer, a second acoustic of a material having a smaller acoustic impedance than even the first acoustic matching layer only at a thickness of 1/4 of the ultrasonic wavelength in the The method for manufacturing an ultrasonic probe according to claim 1 , further comprising: a second acoustic matching layer forming step of forming a matching layer. 3. The ultrasonic probe according to claim 2, wherein the material having an acoustic impedance smaller than that of the first acoustic matching layer in the second acoustic matching layer forming step is an epoxy resin. Production method. 4. The ultrasonic probe according to claim 1, wherein in the gap forming step, gaps are formed in the piezoelectric vibrator and the acoustic matching layer at equal intervals based on predetermined conditions. Method of manufacturing a contact. 5. The step of forming a gap portion includes the following steps: d <λ / ｛1+ | sin (θ / 2) |｝ (where, d: interval between divided centers of transducers, λ: wavelength of ultrasonic waves, θ: scanning angle) 5. The method for manufacturing an ultrasonic probe according to claim 4, wherein the ultrasonic probe is formed at regular intervals satisfying the conditional expression. 6. The manufacturing of the ultrasonic probe according to claim 4, further comprising a step of forming an acoustic lens portion on the acoustic matching layer after the completion of the gap portion forming step. Method.