JPS6260010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic probe equipped in an ultrasonic diagnostic apparatus.

In recent years, in order to expand the characteristics of ultrasound emitted from an ultrasound probe to a high frequency band, the acoustic impedance of the piezoelectric ceramic that excites the ultrasound has been changed to the acoustic impedance of the subject (the main component of living organisms is water, so Acoustic impedance; 1.5×10 ⁶ Kg/m ²
It can be approximated to sec. ), and the first ultrasonic transducer to be attached to such an ultrasonic probe.
Something like the one shown in the figure is being considered. As shown in FIG. 1, the ultrasonic transducer 1 consists of a plurality of piezoelectric ceramics 3 (acoustic impedance: 30 to 40 Kg/m ² ·sec) cut into tin strips having electrode layers 2a and 2b on the upper and lower surfaces. ) are arranged in parallel on a packing material 4, and a first matching layer 5 such as a glass layer (acoustic impedance;
10 to 14×10 ⁶ Kg/m ² ·sec), and then a second matching layer 6 is formed on the first matching layer 5, for example, an epoxy resin layer mixed and dispersed with glass powder (acoustic impedance: 2.5 to 4). x10 ⁶ Kg/m ² sec). Note that the thickness of the first matching layer 5 and the second matching layer 6 is the same as that of the matching layer 5.
or 1/ of the wavelength λ of the ultrasonic wave propagating in the matching layer 6
Ideally, it should be adjusted to 4.

In an ultrasonic probe, generally an ultrasonic transducer 1 is used, as shown in FIG.
An acoustic lens 7 made of, for example, silicone rubber is bonded to the ultrasonic emission surface of the piezoelectric ceramic 3 with a room temperature vulcanizable silicon adhesive 8, and an electrode layer 2b on the piezoelectric ceramic 3 and a first matching layer are bonded to each other. 5, and the first matching layer 5 and the second matching layer 6 are bonded together with an adhesive.

In this case, since the acoustic impedance of the adhesive is extremely small, for example, 1×10 ⁶ Kg/m ² sec, the acoustic impedance of the piezoelectric ceramic 3 is sequentially adjusted despite the presence of the first and second matching layers 5 and 6. Therefore, due to the presence of the adhesive, the ultrasonic waves emitted from the piezoelectric ceramic 3 cannot be emitted from the surface of the acoustic lens 7 without distorting its characteristics. There is a problem. Furthermore, since the ultrasonic probe is moved over the surface of the subject while the surface of the acoustic lens 7 is in direct contact with the subject, stress is applied to the silicone adhesive 8, causing the acoustic lens 7 and the second Another problem is that the matching layer 6 easily peels off after a short period of use.

This invention was made in view of the above circumstances, and it is possible to improve the acoustic impedance of an ultrasonic transducer by reducing the number of adhesive layers as much as possible, and to easily remove the acoustic lens from the ultrasonic transducer. The object of the present invention is to provide an ultrasonic probe that does not peel off.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a partially cutaway schematic perspective view showing a state in which an acoustic lens is attached to an ultrasonic transducer in an ultrasonic probe which is an embodiment of the present invention, and FIG. , B are explanatory diagrams showing a procedure for forming an ultrasonic transducer to which an acoustic lens is attached.

An ultrasonic probe that is an embodiment of this invention is
It is characterized by comprising an ultrasonic transducer fitted with an acoustic lens as shown in FIG.

In FIG. 2, an ultrasonic transducer 10
, a plurality of piezoelectric ceramics 13 having electrode layers 12a and 12b on the upper and lower surfaces and cut into strips are arranged in parallel on a backing material 14, and in order to reduce the acoustic impedance on the piezoelectric ceramics 13. A single-layer matching layer 15, for example, a glass layer, is bonded to the top surface of the ultrasonic transducer 10, and a silicone rubber and a polyimide layer 16 are integrally formed thereon. An acoustic lens 17 having a lower surface is bonded thereto.

The ultrasonic transducer 10 equipped with the acoustic lens 17 having the above configuration can be formed as follows. That is, as shown in FIG. 3, a rectangular plate-shaped piezoelectric ceramic body 13a with electrode layers 12c and 12d provided on the upper and lower surfaces is bonded with, for example, epoxy resin on a backing material 14 made of rubber or the like and having a substantially rectangular parallelepiped shape. The ultrasonic transducer precursor 18 is then bonded to the upper electrode layer 12d of the piezoelectric ceramic body 13a with a glass body 15a having the same planar shape as the piezoelectric ceramic body 13a using, for example, an epoxy resin adhesive. form. Next, by cutting the glass body 15a and the piezoelectric ceramic body 13a in parallel to a direction perpendicular to the longitudinal direction of the ultrasonic transducer precursor 18,
On the backing material 14 as shown in FIG. 4B,
An ultrasonic transducer 10 is obtained in which a plurality of rectangular piezoelectric ceramics 13 having matching layers 15 made of glass are arranged in parallel.
In addition to the above-mentioned method, the following method can be used for bonding the electrode layer 12d and the glass body 15a. That is, silver paint is applied to the upper surface of the rectangular plate-shaped piezoelectric ceramic body 13a and the lower surface of the glass body 15a as shown in the figure, and after the applied silver paint has dried, the silver paint applied surface of the piezoelectric ceramic body 13a and the glass body 15 are coated.
The piezoelectric ceramic body 13 is formed by overlapping the silver paint-coated surface of a and baking it in, for example, an electric furnace.
By fusing the silver paint of a and the silver paint of the glass body 15a, the piezoelectric ceramic body 13a and the glass body 15a can be bonded together through the fused silver layer. If such an adhesion method is adopted, the fused and formed silver layer can be used as the electrode layer 12d, and moreover, it can be used as the electrode layer 12d without using an organic polymer adhesive that adversely affects acoustic impedance. The glass body 15a can be firmly bonded to the glass body 15a.

On the other hand, a hollow-shaped acoustic lens 17 having a polyimide layer 16 on the lower surface as shown in FIG.
It can be formed as follows. That is, a film made of intermediate polyamide carboxylic acid obtained by preliminary polycondensation of pyromellitic anhydride and diamine is placed on the bottom surface of the female mold having a rectangular recess similar to the piezoelectric ceramic body 13a, On top of this, a predetermined amount of silicone resin containing a vulcanizing agent is filled, and then a film made of intermediate polyamide carboxylic acid and a female mold filled with the silicone resin are placed on the upper curved surface of the semicylindrical acoustic lens 17. A male mold having a flat inner concave surface is fitted and pressed while heating. Then, the intermediate polyamide carboxylic acid that forms the film is dehydrated and becomes polyimide, and the silicone resin becomes silicone rubber through a crosslinking reaction, and is also partially crosslinked with polyimide to form silicone rubber and polyimide. and are united together. After heating and pressing with the male die for a predetermined period of time, the male die and the female die are removed to obtain a semicylindrical acoustic lens 17 having a polyimide layer 16 on the lower surface as shown in FIG. 4A.

Next, a fourth
After installing the ultrasonic transducer 10 shown in Figure B, a fourth
Polyimide layer 16 of acoustic lens 17 shown in Figure A
By bonding them with, for example, an epoxy resin adhesive, an acoustic lens 1 as shown in FIG.
It is possible to obtain an ultrasonic probe comprising an ultrasonic transducer 10 equipped with an ultrasonic transducer 7.

The acoustic impedance of polyimide is approximately 3×10 ⁶
Kg/m ² sec, and the acoustic lens 17 having such a polyimide layer is connected to the ultrasonic transducer 1.
0, the polyimide layer functions as a matching layer, so the matching layer in the ultrasonic transducer 10 can be a single glass layer, and the matching layer formed on the piezoelectric ceramic 13 can be simplified. Can be done. Furthermore, in the past, when attaching an acoustic lens to an ultrasonic transducer having a matching layer consisting of two layers, there were three adhesive layers that extremely deteriorated the acoustic characteristics, but according to the present invention, the electrode layer 12b, a matching layer 15 consisting of only a glass layer, and a polyimide layer 1 of this matching layer 15 and an acoustic lens 17.
Since it only requires two adhesive layers with 6,
The number of adhesive layers can be reduced to prevent the adhesive from adversely affecting acoustic properties. Piezoelectric ceramic 13 and matching layer 1 are formed by baking silver paint.
5, the number of adhesive layers can be further reduced by one, and an adverse effect on the acoustic properties can be further prevented. Furthermore, a polyimide layer 16 with high mechanical strength is integrally formed with silicone rubber on the lower surface of the acoustic lens 17, and since the polyimide layer 16 is extremely firmly adhered to the epoxy adhesive, the acoustic lens 17 Even if the ultrasonic probe equipped with the ultrasonic transducer 10 attached thereto is moved over the surface of the object while being in strong contact with the object, the silicone rubber body and the polyimide layer 16 will peel off at the acoustic lens 17. Or, the acoustic lens 17 and the matching layer 15 will not separate.

Although one embodiment of the present invention has been described in detail above, it goes without saying that the present invention is not limited to the above-mentioned embodiment and includes various modifications without changing the gist of the invention.

In the above embodiment, the raw materials for the polyimide forming the lower surface of the acoustic lens were pyromellitic anhydride and diamine, but they may also be other aromatic carboxylic acid anhydrides and diamines.

According to the invention described in detail above, it is possible to prevent deterioration of ultrasonic characteristics due to the presence of an adhesive layer, and therefore it is possible to provide an ultrasonic probe with good ultrasonic characteristics over a high frequency band. Furthermore, since the polyimide layer is formed on the acoustic lens, the acoustic lens does not easily peel off from the matching layer, and an inexpensive ultrasonic probe with a single matching layer can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a conventional ultrasonic transducer equipped with an acoustic lens, FIG. 2 is a schematic perspective view showing an embodiment of the present invention, and FIGS. 3 and 4 A and B. FIG. 2 is an explanatory diagram showing a procedure for forming an ultrasonic transducer to which an acoustic lens is attached. 10... Ultrasonic transducer, 12a, 1
2b... Electrode layer, 13... Piezoelectric ceramic, 14
... Bucking material, 16 ... Polyimide layer, 17
...acoustic lens.

Claims (1)

[Claims] 1. In an ultrasonic probe in which an acoustic lens is attached to an ultrasonic transducer having a piezoelectric ceramic layer and a matching layer, a polyimide layer is formed on the lower surface of the acoustic lens body simultaneously with the formation of the acoustic lens, and the polyimide layer is covered with the An ultrasonic probe characterized by having a matching layer laminated thereon.