JP3385335B2 - Method of manufacturing array type ultrasonic probe and acoustic lens - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array type ultrasonic probe having an acoustic lens (hereinafter referred to as an array type probe), and particularly to suppressing unnecessary ultrasonic waves from the outer circumference of the acoustic lens. And an array type probe having a narrow beam width (see: Japanese Patent Application Nos. 7-48978 and 7-2037).
88).

[0002]

[Prior art]

[Background of the Invention] An array type probe is useful, for example, in an ultrasonic diagnostic apparatus for medical use as an ultrasonic wave transmitting / receiving unit. For example, strip-shaped piezoelectric elements having a minute width are arranged in the width direction (long axis direction), and linear or sector drive is performed in the same direction. In such a device, generally, an acoustic lens is provided in the length direction (short axis direction) of the piezoelectric element, and ultrasonic waves are converged and transmitted / received to increase the resolution in the same direction.

"One Example of Prior Art" FIG. 5 is a diagram of an array type probe for explaining a conventional example of this kind. FIG. 5 (a) is a schematic front sectional view, and FIG. 5 (b) is a side sectional view. FIG. 1C is a diagram of the acoustic lens. The array type probe is formed by arranging strip-shaped piezoelectric elements 2 made of PZT (lead zirconate titanate) or the like on a backing material 1 in the long axis direction. Electrodes are provided on both main surfaces, and a filler is embedded between the grooves (not shown). And
On the front surface of the piezoelectric element 2, a two-layer acoustic matching layer 3 (ab) is provided which measures acoustic impedance matching with a detected body (living body or the like) and improves ultrasonic wave propagation efficiency. Further, the acoustic lens 4 is provided on the acoustic matching layer 3. The piezoelectric element group is provided with a flexible substrate or the like (not shown) that is connected to the electrodes of each piezoelectric element 2, and the mold layer 5 is provided on the outer periphery thereof. Reference numeral 6 in the drawing is a base, and reference numeral 7 is a case.

The acoustic lens 4 may basically be provided on the acoustic matching layer 3 so as to have the same length as the piezoelectric element 2 as shown in FIG. However, in reality, the piezoelectric element 2
In order to prevent the acoustic lens 4 from being displaced or disengaged with respect to, the leg portion 4b is provided on the outer periphery of the lens portion 4a [see FIG.
c) ”. In addition, when the sound velocity is slower than that of the detected body (living body), it is convex, and when it is fast, it is concave.

Then, for example, as shown in FIG. 7, the lens forming die 10 is used. The lens molding die 10 includes a concave first die 8 having a curvature and a convex second die 9. First mold 8 and second mold 9
Has a space 11 corresponding to the acoustic lens 4 between them. Then, a silicon-based resin is injected between the first die 8 and the second die 9 and pressure-welded.

Further, generally, the acoustic lens 4 (the length L of the lens portion 4a) is set to a large value in advance, and the acoustic lens 4 is also applied to a piezoelectric element 2 smaller than this. The reason is that since the lens portions 4a have the same curvature, if the length L of the piezoelectric element 2 is constant,
This is because it basically has the same focus F as shown in FIG. 8 (ab) (however, since the thickness increases, the attenuation of ultrasonic waves increases). By doing so, the versatility of the acoustic lens 4 is enhanced, and it is not necessary to manufacture the molding die 10 each time. It should be noted that the manufacturing of the first mold 8 having a curvature requires a very high technique and the manufacturing cost thereof is high.

[0007]

[Problems to be Solved by the Invention]

“Problems of the prior art” However, in the array type probe having the above-described configuration, ultrasonic waves emitted from both ends of the acoustic lens 4 expand the beam width as the accuracy of the diagnostic apparatus and the like increases.
It has recently become clear that it adversely affects resolution and the like. That is, the acoustic lens 4 is set larger than the length of the piezoelectric element 2 as described above. For this reason, it was found that the ultrasonic wave propagates especially in the lens portion 4a and leaks from the outer periphery of the acoustic lens 4 to widen the beam width of the ultrasonic wave (see FIG. 9).

[Problems and Objects of the Invention] [0008] The present invention is to solve how to eliminate the leakage of ultrasonic waves from the end of the acoustic lens and to manufacture an acoustic lens having excellent versatility. It is an object of the present invention to provide an array type probe having excellent resolution and a method for manufacturing an acoustic lens.

[0009]

According to the present invention, the leg portion extending from the outer periphery of the lens portion is provided with the lens portion of the acoustic lens covering the piezoelectric element group being equal to or less than the length of the piezoelectric element. The first solution means is to use an ultrasonic shield that is a separate body from the lens part, and integrate the lens part and the leg part.

As a method of manufacturing such an acoustic lens, a step of forming a leg portion between a concave first mold and a convex second mold having the above-mentioned curvature, and a lens portion And forming the lens portion and the leg portion into one body is a second solving means.

[0011]

In the first solving means of the present invention, since the lens portion is equal to or less than the length of the piezoelectric element and the leg portion is the ultrasonic shield, the leakage of the ultrasonic wave from the outer circumference of the acoustic lens is prevented. . Further, since the lens portion and the leg portion are integrated as a separate body, there is an action of making the lens portion common.

Further, in the second solving means, the step of forming the leg portion and the step of forming the lens portion are separated,
There is an effect that the length of the lens unit can be controlled by using the same first mold. Examples of the present invention will be described below.

[0013]

[First Embodiment] FIG. 1 is a view for explaining an embodiment corresponding to the first solving means of the present invention. FIG. 1 (a) is a sectional view of an array type probe, and FIG. 1 (b) is an acoustic lens. FIG. It should be noted that the same parts as those of the previous conventional example are given the same numbers to simplify the description. In the array type probe, similarly to the above, the piezoelectric elements 2 are arranged on the backing material 1 to form the acoustic matching layer 3 (ab),
Further, an acoustic lens 4 is provided. In this embodiment, the acoustic lens 4 includes the lens portion 4a described above and the side plate 4c (corresponding to the leg portion 4b described above). As described above, the lens portion 4a is formed in a convex shape so as to match the length of the piezoelectric element 2, and is made of, for example, a silicon material having a slower sound speed than the living body. The side plate 4c has a hook shape, and is connected to the outer peripheral end surface of the lens portion 4a,
And are made of, for example, a polyimide resin having a different acoustic impedance. Then, the two are joined by an adhesive or thermocompression to be integrated.

As described above, in this embodiment, the piezoelectric element 2 and the lens portion 4a have the same length, and the side plate 4c having different acoustic impedance is provided on the outer periphery of the lens portion 4a. Therefore, since the acoustic impedances of the lens portion 4a and the side plate 4c are different, the ultrasonic waves are reflected and prevented from propagating into the side plate 4c. That is, the side plate 4c functions as an ultrasonic shield. Therefore, the leakage of ultrasonic waves from the outer circumference of the acoustic lens 4 is prevented. Therefore, the spread of the beam width is prevented and the resolution is improved.

Further, since the lens portion 4a and the side plate 4c are joined separately, the lens portion 4a is set to a large size in advance,
It may be cut according to the length of the piezoelectric element 2. Therefore, it is not necessary to manufacture the above-mentioned first mold 8 according to the length of the lens portion 4a each time the length of the piezoelectric element 2 is different.
For this reason, the versatility of the acoustic lens 4 is increased without increasing the cost.

[0016]

[Second Embodiment] FIG. 2 is a schematic view of a mold for explaining an embodiment corresponding to the manufacturing method of the second solving means in the present invention. The acoustic lens 4 is formed using the molding die 10 as described above. In this embodiment, the second mold 9a has a convex shape with a step at the tip. And the second mold 9a
Abutting the tip corner part of the concave part with the curvature of the first mold 8,
A hook-shaped space corresponding to the side plate 4c is formed. Next, a molten polyimide resin is injected into a hook-shaped space portion from a hole 12a (not shown) of the first mold and solidified to form a side plate 4c. Then, the second mold 9a is removed, and rubber-like silicon is injected into the concave space portion. Next, the injected silicon is pressed by the convex third mold 9b to form the lens portion 4a and integrate the side portion 4c.
It should be noted that when pressing, the surplus silicon is removed from the first mold 8 and the third mold.
It is formed by protruding from between the mold (side plate 4c).

With such a manufacturing method, the first die 8
While keeping the length of the concave surface of the
The length of the lens portion 4a can be controlled by changing it with the mold 9a. Therefore, the first mold 8 can be shared and the inexpensive and versatile acoustic lens 4 can be manufactured. Since the leg portion 4c is used as the ultrasonic shield as described above, leakage of ultrasonic waves from the outer circumference of the acoustic lens 4 is prevented.

[0018]

[Other Matters] In the above embodiments, the side plate 4c of the acoustic lens is used.
Has a hook shape, but there is no mold layer 5 or the like on the outer periphery or it is extremely thin, and for example, is approximately 1 / the length of the piezoelectric element 2.
In the case of 50 or less, the side plate 4c may simply be a flat plate (Fig. 3).

Although the lens portion 4a is made to match the length of the piezoelectric element 2, the length of the lens portion 4 may be shorter than that of the piezoelectric element 2 to provide the hook-shaped side plate 4c. In this case, the side plate 4
Since the ultrasonic wave is shielded by c, the lens portion 4a has a substantial length of the piezoelectric element 2 (aperture length of the ultrasonic wave) "4th
Figure ". In this case, the hook portions of the side plate 4c are located on the upper surfaces of both ends of the piezoelectric element 2, and the ultrasonic wave from the piezoelectric element directly propagates. Therefore, for example, a foamed resin in which bubbles are contained in a polyimide resin may be used to complete the shielding by the bubbles.

In the second embodiment, the polyimide resin for forming the side plate 4c is injected and solidified, and then the silicon for forming the lens portion 4a is injected. 9 may be used to form the side plate c by injecting a resin after the lens portion 4a. Moreover,
The side plate 4c is not formed by injection, but the side plate 4c formed in advance may be provided on the inner circumference of the first mold 8 or the outer circumference of the second mold by an adhesive or the like. In addition, as described above, the resin forming the side plate 4c may be a foamed resin containing air bubbles in order to enhance the shielding effect. The side plate 4c is not limited to polyimide and may be silicon mixed with bubbles. Basically, the acoustic impedance is different from that of the lens 4a, or is an ultrasonic shield made of foam or the like that enhances the shielding effect. I wish I had it.

Further, although both ends of the acoustic lens 4 are shown as open ends for convenience of explanation, they are generally closed, and this is not excluded from the present invention. As described above, the present invention can be variously modified, and the point is that an acoustic lens integrally formed with a lens part and a side plate composed of an ultrasonic shield as a separate body, and an array type probe using the same. The child basically belongs to the technical scope of the present invention.

[0022]

According to the present invention, the lens portion of the acoustic lens covering the piezoelectric element group is equal to or less than the length of the piezoelectric element, and the leg portion extending from the outer periphery of the lens portion is referred to as the lens portion. The ultrasonic shield is a separate body, and the lens portion and the leg portion are integrated. The method further includes a step of forming a leg portion between a concave first die having a curvature and a convex second die, and a step of forming a lens portion. Since the acoustic lens is manufactured by integrating the and, it is possible to provide an acoustic lens with excellent versatility, and also to eliminate the leakage of ultrasonic waves from the end of the acoustic lens to provide an array type probe with excellent resolution. Can be provided.

[Brief description of drawings]

1A and 1B are diagrams illustrating a first embodiment of the present invention, FIG. 1A is a side sectional view of an array type probe, and FIG. 1B is a diagram of an acoustic lens.

FIG. 2 is a view for explaining the manufacturing method of the second embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are schematic views of a mold.

FIG. 3 is a side sectional view of an array type probe for explaining another example of the first embodiment of the present invention.

FIG. 4 is a side sectional view of an array type probe for explaining still another example of the first embodiment of the present invention.

5A and 5B are views for explaining a conventional example, where FIG. 5A is a front sectional view of an array type probe, FIG. 5B is a sectional side view of the same, and FIG.
Is a diagram of an acoustic lens.

FIG. 6 is a side sectional view of an array type probe for explaining a conventional example.

FIG. 7 is a cross-sectional view of a molding die for an acoustic lens for explaining a conventional example.

FIG. 8 is a schematic side sectional view of an array type probe for explaining a conventional example.

FIG. 9 is a side sectional view of an array type probe for explaining the problems of the conventional example.

[Explanation of symbols]

1 backing material, 2 piezoelectric element, 3 acoustic matching layer, 4
Acoustic lens, 4a lens part, 4b leg part, 4c side plate, 5 mold layer, 6 base, 7 case, 8 1st
Mold, 9 Second mold, 10 Mold for molding, 11 Space part.

Continuation of front page (56) References JP 62-268536 (JP, A) JP 63-177700 (JP, A) JP 57-113692 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H04R 1/34 330 G10K 11/30 H04R 17/00 332

Claims (2)

(57) [Claims] 1. A piezoelectric element group in which a plurality of piezoelectric elements are arranged in the width direction, and an acoustic lens including a lens portion having a curvature portion in the length direction of the piezoelectric element and a leg portion is covered on the piezoelectric element group. In the array type ultrasonic probe consisting of, the lens portion of the acoustic lens is equal to or less than the length of the piezoelectric element,
An ultrasonic probe in which the leg portion is an ultrasonic shield that is separate from the acoustic lens, and the lens portion and the leg portion are integrated. 2. A resin having a concave first mold having a curvature and a second mold having a convex shape, wherein a resin is formed in a space formed by fitting the first mold and the second mold. In order to form an acoustic lens including a lens portion having a curvature and a leg portion extending from the outer periphery of the lens portion, a leg portion is provided between the first mold and the second mold. A method of manufacturing an acoustic lens, characterized in that the step of forming and the step of forming a lens part are separately provided, and the lens part and the leg part are integrated.