JPH0523331A - Ultrasonic probe and manufacture of piezo-electric vibrator plate used therefor - Google Patents

Abstract

PURPOSE:To achieve higher improving effect of an ultrasonic beam weighted in amplitude. CONSTITUTION:In an ultrasonic probe in which a piezo-electric vibrator plate 1 is arranged being divided in an array, the piezo-electric vibrator plate 1 is divided in a stripe in the direction parallel with an array direction A with a plurality of cuts 3, 3... to be formed toward other main surfaces on which a support plate 2 of a conductor is mounted from one main surface while parts divided with the cuts 3 are polarized in intensity as higher at the center thereof and lower toward the end thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe and a method for manufacturing a piezoelectric vibrator plate used for the probe.

[0002]

2. Description of the Related Art Conventionally, in order to reduce a side lobe level and improve an ultrasonic beam, the polarization of a piezoelectric vibrator plate constituting an ultrasonic probe which is a piezoelectric body is changed by the piezoelectric vibrator. In the direction orthogonal to the plate arrangement direction, that is, in the thickness direction of the ultrasonic probe, it is effective to reduce the sound pressure from the central portion to the end portion and weight the emitted sound pressure. It has been confirmed.

As one of the publicly known examples using such a method, there is one in which the polarization intensity is changed according to a continuous function such as a raised cosine, a Hamming function, or a Gaussian distribution. As shown in FIG. 15B, there is one in which the polarization intensity is changed according to a stepwise function (in the figure, the horizontal axis represents the thickness direction dimension, and the vertical axis represents the electromechanical coupling coefficient k). .

FIG. 15A shows a method of changing the above-mentioned polarization intensity according to a stepwise function. The piezoelectric vibrator plate 1 has stripe-shaped electrodes 10 parallel to the arrangement direction A.
Are attached, and by applying to each electrode 10 voltages V1, V2, and V3 that are high at the center and are low toward the ends,
A polarized state as shown by the length of the arrow in FIG. 15A is obtained.

[0005]

However, in the above-mentioned conventional example, in order to obtain the piezoelectric vibrator plate 1 in which the polarization intensity is changed according to a continuous function, generally a complicated process is required and a desired distribution state is obtained. The latter method, which is relatively simple to manufacture, is superior because it has the drawback of increasing the number of control factors to obtain the polarization. An unnecessary vibration mode is generated in a portion between the electrodes 10, that is, in a portion where the electrode 10 is absent, or in a portion where the applied voltage V is low in the adjacent two electrodes 10, and the ultrasonic beam of the ultrasonic beam by amplitude weighting is generated. It had a problem of reducing the effect of improvement.

In FIG. 16, after the polarization is performed by the above-mentioned method, the striped electrode 10 is removed, and the piezoelectric vibrator plate 1 having the electrodes attached again over the entire main surface is divided in the direction orthogonal to the arrangement direction A to form the electrodes. It shows the results of measuring the resonance frequency and the anti-resonance frequency of the part which is polarized with the electrode and the part where the stripe electrode 10 is not attached at the time of polarization.

In this figure, there is a resonance and anti-resonance point at 3 to 5 MHz in the part where the electrode 10 is present, but in the part where the electrode 10 is not present, another 6 to 9 MHz in addition to around 3 to 5 MHz.
There are resonance and anti-resonance points in the vicinity. This is the case with two adjacent electrodes 10 and similar results are obtained for a part of the lower applied voltage V. The cause is that the piezoelectric element part without the electrode 10 is affected by the adjacent electrode 10. hand,
It is thought that this is because it is polarized in an oblique direction, not perpendicular to the main surface.

For this reason, when the piezoelectric element is driven, the portion without the electrode 10 and the portion with the lower applied voltage V of the two adjacent electrodes 10 are not perpendicular to the main surface. As a result, unnecessary vibration is generated in the oblique direction, which reduces the effect of improving the ultrasonic beam by amplitude weighting.

The present invention has been made to solve the above drawbacks, and is an ultrasonic probe having a high effect of improving an ultrasonic beam by amplitude weighting, and a piezoelectric vibration used for the ultrasonic probe. An object is to provide a method for manufacturing a child board.

[0010]

According to the present invention, the above object is to provide an ultrasonic probe in which piezoelectric vibrator plates 1 are divided and arranged in an array as shown in FIG. 1 corresponding to an embodiment. , The piezoelectric vibrator plate 1 is formed in a direction parallel to the arrangement direction A by a plurality of cuts 3 formed from one main surface toward the other main surface to which the support plate 2 of the conductor is attached. Provided is an ultrasonic probe characterized in that each part divided into stripes and divided by the notch 3 is polarized at a higher polarization center and a lower polarization intensity toward the ends. It is achieved by

The piezoelectric vibrator plate 1 used in the above ultrasonic probe has a structure in which a support plate 2 made of a conductor is attached to one main surface of the piezoelectric vibrator plate 1 before polarization, and then the other main plate. The oscillator plate is divided into stripes in a direction parallel to the arrangement direction A by making a notch 3 in the plane, and then a polarization voltage V is applied to each of the divided portions, which is higher in the central portion and lower in the end portions. It is obtained by

[0012]

According to the above structure, the piezoelectric vibrator plate 1 is weighted because the electromechanical coupling coefficient k in the direction orthogonal to the arrangement direction A is changed stepwise, and the side lobe level is lowered. Also, the electromechanical coupling coefficient k
Since the notch 3 is formed at the changed portion of, the unnecessary vibration in the oblique direction is reduced, and the effect of improving the ultrasonic beam is enhanced.

Further, since the piezoelectric vibrator plate 1 is reinforced by the support plate 2 made of a conductor, cracks and the like at the time of forming the notch 3 are surely prevented. Further, in the invention according to claim 2, the notch 3 is formed with a depth to reach the support plate 2, and the polarization is made independently without being affected by other adjacent electrodes.

In the invention of claim 3, the support plate 2
Are provided on the electrodes formed on the piezoelectric vibrator plate 1, and variations in polarization can be prevented, and soldering of the signal line 6 or the ground electrode 5 can be facilitated.

Further, in the invention of claim 4, the support plate 2 is used as an acoustic matching layer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention. In the figure, A indicates the arrangement direction of the piezoelectric vibrator plates 1, and B indicates the thickness direction. First, the entire one main surface of the piezoelectric vibrator plate 1 is shown. Forming the electrode 4 uniformly over the
The support plate 2 is formed on the other main surface by using a conductive paste or the like.

After that, a notch 3 is made on one of the main surfaces using a dicing saw. The notches 3 are formed along the arrangement direction A and from the surface where the electrodes 4 are formed toward the support plate 2 side. As a result, the piezoelectric vibrator plate 1 is divided into stripes along the arrangement direction A. Further, as will be described later, the notch 3 has a depth of at least more than 1/2 of the thickness so that interference between adjacent portions does not occur during polarization, and the notch 3 is formed at the time of forming the notch 3. The support plate 2 completely prevents cracking or warpage in the subsequent polarization process.

Through the above steps, the electrode 4 on the main surface in which the notch 3 is formed is divided in the thickness direction, and thereafter, the voltages V1, V2, and V3 are applied to each divided electrode 4 while facing each other. The supporting plate 2 to be grounded is dropped to the ground E for polarization. The applied voltage V for polarization is set so that the central part becomes the highest and the voltage becomes lower stepwise toward the end, and the polarization operation causes the piezoelectric vibrator plate 1 to move as shown by the arrow in the figure. The maximum value is in the center, and the polarization becomes gradually lower toward both ends.

This polarization operation is carried out in insulating oil,
Since the cut 3 portion is filled with insulating oil and the cut 3 is deeply formed, each divided portion of the piezoelectric vibrator plate 1 is independently polarized without being affected by the adjacent electrode 4.

A second embodiment of the present invention is shown in FIG. In the following description of the embodiments, the same configurations as those of the above-described embodiments are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the notch 3 is formed so as to reach the support plate 2, and the piezoelectric vibrator plate 1 is completely divided into stripes along the arrangement direction A. As a result, each divided portion of the piezoelectric vibrator plate 1 has a support plate 2
The state in which the adjacent electrodes 4 are connected to each other can be completely eliminated from the influence of the adjacent electrode 4 at the time of polarization.

Further, the contraction due to heat during polarization is caused by the support plate 2
Since it occurs inside, the occurrence of warpage in the direction orthogonal to the arrangement direction A is completely prevented.

FIG. 3 shows a third embodiment of the present invention, in which, for example, an Ag baking electrode 4 is provided under the support plate 2. The electrode 4 operates as follows. That is,
Taking the piezoelectric vibrator plate 1 of a commonly used 3.5 MHz linear probe as an example, its size is about 16 mm.
When the conductive paste is used, a potential difference is generated in the support plate 2 due to the resistance of the conductor, and each divided portion can be polarized with a uniform polarization strength. There are cases where you cannot. Therefore, by inserting the Ag printing electrode 4, which is generally used for polarization, between the piezoelectric vibrator plate 1 and the support plate 2 of the conductor, there is no potential difference and it is possible to perform polarization with uniform polarization intensity.

FIGS. 4 and 5 show an embodiment showing a state in which an ultrasonic probe is constructed from the piezoelectric vibrator plate 1 formed as described above. In this embodiment, the conductor 2 on the electrode 4 is provided at a portion of the piezoelectric vibrator plate 1 excluding the edge portion, and the ground electrode 5 or the signal line 6 is soldered to the exposed portion of the electrode 4. It

This embodiment is effective when a material such as a conductive paste that is difficult to solder is used for the support plate 2, and when the signal line 6 or the ground electrode 5 is joined to the exposed portion of the electrode 4, A conductor made of the same material is attached to the exposed portion with the same thickness as that of the support plate 2.

Although FIGS. 4 and 5 show the case where the signal line 6 and the like are joined after the support plate 2 is formed, the electrodes 4 are formed on both surfaces of the piezoelectric vibrator plate 1 in addition to this. Electrode 4
The support plate 2 may be provided after the signal line 6 and the like are joined to the.

Other than the above, the signal lines 6 and the like can be attached by soldering directly to a conductor or by using the support plate 2.
It is possible to insert a metal mesh when attaching the.

6 to 8 show how to connect the electrodes 4 on the main surface with the notches 3. FIG. 6 shows a method of attaching the electrodes 11 over the entire main surface, and FIG. 7 shows each notch. FIG. 8 shows a method of attaching the striped electrode 12 so as to straddle 3 and a method of removing the divided electrode 4 and attaching the electrode 13 again over the entire main surface.

As a method of forming the electrode 4, it is possible to adopt a means such as a conductive paste, plating, vapor deposition or the like, and it is desirable to use a means that can be attached at room temperature in order to avoid depolarization by heating.

In each case, the notch 3 is filled with an epoxy resin 14, silicon resin or the like to prevent the piezoelectric vibrator plate 1 from cracking.

FIG. 6A shows the distribution of the mechanical coupling coefficient k in the thickness direction. FIG. 9 shows an embodiment in which an ultrasonic probe is formed using the piezoelectric vibrator plate 1 configured as described above. In this embodiment, the piezoelectric vibrator plate 1 is divided into an array in the arrangement direction A, a matching layer 15 is laminated on the ground-side main surface to which the support plate 2 is attached, and an acoustic lens 16 is arranged on the upper surface. To be done.

An electrode 17 is newly provided on the other main surface facing the earth side main surface, and this electrode 1
7 is connected to a flexible printed board 19 having a signal line pattern 18, and as shown in FIG. 7B, there is one opening in the direction orthogonal to the arrangement direction A, and the distribution of the electromechanical coupling coefficient k is , The central part is higher and the lower part is stepwise lower toward the end, and the probe is constructed by weighting the radiated sound pressure.

In the figure, 20 is a backing material and 2 is a backing material.
Reference numeral 1 is a printed board (metal foil) on the side of the ground electrode. Another embodiment of aperture control is shown in FIG. In this embodiment, the piezoelectric vibrator plate 1 is divided along the arrangement direction A by the notches 3 and is also divided into an array in the direction orthogonal to the arrangement direction A, and the main surface to which the support plate 2 of each small piece is attached. Signal lines 6 are connected to the electrodes 4 on the main surface facing each other. Further, a changeover switch 7 is arranged between each of the signal lines 6, and by operating the changeover switch 7, three types of openings in the thickness direction are controlled as shown in FIG.

In FIG. 10, W1 indicates a driving range corresponding to a large opening, W2 indicates a middle opening, and W3 indicates a driving range corresponding to a small opening. FIG. 12 shows another embodiment of aperture control, in which the three small pieces in the central portion are connected by the common electrode 8 and are driven simultaneously, and by operating the switch 7,
As shown in FIG. 13, two types of openings are controlled in the thickness direction.

FIG. 14 shows still another embodiment of opening control. In this embodiment, the piezoelectric vibrator plate 1 is divided into five in the width direction B as in the above-mentioned embodiments,
As shown in (b), the left and right polarization intensities are the same. A changeover switch 7 is provided on the outer piezoelectric vibrator plate 1 at the time of the large opening W1 and a resistor 9 is connected in series.

Therefore, in this embodiment, the driving voltage applied to the outer piezoelectric vibrator plate 1 is lowered by the resistor 9, and the operation of the switch 7 controls two types of openings as shown in FIG. By reducing the number of stages during polarization, the same effect as that obtained by polarization with a larger number of stages can be obtained.

In the above description, the support plate 2 has been described only as a function as an electrode or as a reinforcing member for preventing cracks of the piezoelectric vibrator plate 1 during polarization operation. It is also possible to design and use the plate 2 as the matching layer 15.

[0038]

As is apparent from the above description, according to the present invention, it is possible to eliminate the influence of the adjacent electrodes during polarization and prevent cracks during handling of the piezoelectric vibrator plate.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the present invention, in which (a) shows a state before polarization and (b) shows a polarization state.

FIG. 2 is a diagram showing another embodiment of the piezoelectric vibrator plate.

FIG. 3 is a view showing still another embodiment of the piezoelectric vibrator plate.

FIG. 4 is a diagram showing a method of wiring to a piezoelectric vibrator plate.

5 is a diagram showing a state in which wiring is performed in FIG.

6A and 6B are diagrams showing a method of forming an electrode, FIG. 6A is a side view thereof, and FIG. 6B is a diagram showing a distribution of a mechanical-electrical coupling coefficient.

FIG. 7 is a diagram showing another method of forming electrodes.

FIG. 8 is a diagram showing still another method of forming electrodes.

FIG. 9 is a view showing an ultrasonic probe according to the present invention,
(A) is a whole figure, (b) is a figure showing distribution of a mechanical-electric coupling coefficient.

FIG. 10 is a view showing another embodiment of FIG. 9, and (a)
Is an overall view, and (b) is a view showing a distribution of a mechanical-electrical coupling coefficient.

11 is a diagram showing a state of aperture control in FIG.
(A) shows a small opening state, (b) shows a middle opening state, and (c) shows a large opening state.

12 is a diagram showing still another embodiment of FIG. 9,
(A) is a whole figure, (b) is a figure showing distribution of a mechanical-electric coupling coefficient.

13 is a diagram showing a state of aperture control of FIG.
(A) shows a small opening and (b) shows a large opening.

14 is a diagram showing still another embodiment of FIG. 12,
(A) is a whole figure, (b) is a figure showing distribution of a mechanical-electric coupling coefficient.

FIG. 15 is a diagram showing a conventional example, FIG.
(B) is a figure which shows distribution of a mechanical coupling coefficient.

16A and 16B are diagrams showing problems of the conventional example, in which FIG. 16A shows characteristics of a portion having no electrode, and FIG. 16B shows characteristics of a portion having an electrode.

[Explanation of sign]

1 Piezoelectric vibrator plate 2 Support plate 3 notches 4 electrodes 5 Earth electrode 6 signal lines 7 Changeover switch 8 common electrode 9 resistance V polarization voltage

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoto Matsui             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (9)

[Claims] 1. An ultrasonic probe in which a piezoelectric vibrator plate (1) is divided and arranged in an array, wherein the piezoelectric vibrator plate (1) is a support plate of a conductor from one main surface.
(2) is divided into stripes in a direction parallel to the arrangement direction by a plurality of notches (3, 3 ...) Formed toward the other main surface to which it is attached, and the notches (3) An ultrasonic probe characterized in that each part divided by is polarized with a high polarization intensity at the center and a low polarization intensity toward the end. 2. The ultrasonic probe according to claim 1, wherein the notch (3) is formed to a depth reaching the support plate (2). 3. The support plate (2) is provided on an electrode (4) formed on a piezoelectric vibrator plate (1), and the electrode (4) is provided with a ground electrode (5) or a signal line (6). ) Is connected.
The ultrasonic probe described. 4. An ultrasonic probe according to claim 1, 2 or 3, wherein the support plate (2) is used as a matching layer. 5. A piezoelectric element plate (1) divided by the notch (3) is further divided into an array in a direction orthogonal to the arrangement direction, and each signal line (6) is formed from each small piece.
Switch to each signal line (6)
The ultrasonic probe according to claim 1, wherein (7) is provided, and the opening in the direction orthogonal to the array direction is controlled by the switch (7). 6. The ultrasonic probe according to claim 5, wherein a plurality of the small pieces, which are adjacent to each other in the direction orthogonal to the arrangement direction, are connected by a common electrode (8). 7. A switch (7) for the signal line (6)
7. The ultrasonic probe according to claim 6, wherein the resistance (9) is provided and the value of the resistance (9) is increased from the center to the end in the direction orthogonal to the arrangement direction. Child. 8. A transducer plate (2) is attached to one main surface of a piezoelectric vibrator plate (1) before polarization, and then a notch (3) is made from the other main surface of the plate. (1) is divided into stripes in a direction parallel to the array direction, and then is used for an ultrasonic probe in which a high polarization voltage (V) is applied to each of the divided parts, which is higher in the central part and lower toward the ends. Piezoelectric vibrator plate manufacturing method. 9. Electrodes (4) on both principal surfaces of the piezoelectric vibrator plate (1).
9. The method for manufacturing a piezoelectric vibrator plate used for an ultrasonic probe according to claim 8, wherein the support plate (2) made of a conductor is attached to one of the main surfaces after forming the.