JP2002165793A - Ultrasonic probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe capable of enhancing image resolution by having high electromechanical conversion efficiency and a piezoelectric element with such an optimum shape as to suppress the occurrence of an unnecessary vibrational mode. SOLUTION: The ultrasonic probe 1 is provided with the plurality of piezoelectric elements 2 for generating ultrasonic waves and transmitting/receiving the ultrasonic waves, an acoustic matched layer 3, which is located on the side of the acoustic radiation surfaces of the piezoelectric elements 2 in order to radiate the ultrasonic waves generated by the piezoelectric elements 2, and a backing material 5 serving as a back-surface load material, which is located on the side of the back surfaces of the piezoelectric elements 2 so as to absorb the necessary ultrasonic waves. The ultrasonic probe 1 is constituted by one- dimensionally arranging at least the piezoelectric elements 2. The ratio (w/t) between a thickness t in the direction of the acoustic radiation axis of the piezoelectric element 2 and a width w in the direction of the arrangement of the piezoelectric element 2 is taken constitutionally as 0.3-0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe used for ultrasonic diagnosis for medical or destructive inspection.

[0002]

2. Description of the Related Art Generally, an ultrasonic probe is disclosed in "Revised Medical Ultrasonic Device Handbook" (edited by The Japan Electronics Machinery Association, Corona, 1997.1.20, pp. 68-74). It has a simple structure. Such an ultrasonic probe generally has, for example, a configuration as shown in FIG. FIG.
FIG. 7 is a configuration diagram showing a conventional array type ultrasonic probe, and FIG.
7A is a schematic perspective view showing a configuration of a conventional array type ultrasonic probe, FIG. 7B is a side sectional view of FIG.
FIG. 3C is a perspective view showing only the piezoelectric element of FIG.

As shown in FIG. 7, a conventional array-type ultrasonic probe 50 includes a plurality of piezoelectric elements 51 formed of a piezoelectric ceramic plate having electrodes formed on both surfaces, and a plurality of piezoelectric elements 51 of the plurality of piezoelectric elements 51. Acoustic matching layers 52a, 52b and acoustic lens 53 formed on the surface on the side that transmits and receives sound waves, and back load member 5 formed on the back side of the plurality of piezoelectric elements 51
4 are integrated to form a structure in which the plurality of piezoelectric elements 51 are one-dimensionally arranged.

The piezoelectric element 51 is connected on the signal line side by a flexible printed board 55 formed of a copper foil 55a and an insulating resin 55b such as polyimide, and the ground on the acoustic matching layers 52a and 52b is a common electrode as a conductive electrode. Are connected by soldering or conductive resin using the wire 56 or foil, and are covered with a protective resin 57.

The piezoelectric element 51 is vibrated by a voltage pulse applied from an observation device (not shown), and
Ultrasonic waves are radiated through 2a and 52b and the acoustic lens 53. The acoustic matching layers 52a and 52b are required for the piezoelectric element 51 in order to efficiently propagate the emitted ultrasonic waves to the subject. On the other hand, the back load member 54 formed on the surface opposite to the acoustic matching layers 52a and 52b has a function of suppressing unnecessary vibration.

The above-mentioned array type ultrasonic probe 50 has a thickness t of one piezoelectric element 51 in the acoustic radiation axis direction, as described in, for example, Japanese Patent Publication No. 62-2813.
And the width (w /
t) is 0.8 or less, and particularly w / t = 0.66 (w =
0.4 mm, t = 0.6 mm) has been proposed.

[0007]

However, the array-type ultrasonic probe described in Japanese Patent Publication No. 2813/1987 has a thickness t of one piezoelectric element 51 in the direction of the acoustic radiation axis.
And the width (w) of the width W in the direction in which the piezoelectric elements 51 are arranged.
If (/ t) is extremely smaller than 0.8, the following problems occur.

The piezoelectric element 51 has a width W and a thickness T (w /
When t) is set to w / t <0.3, the vibration mode in the lateral direction is small, but the higher-order vibration in the thickness direction is large.
The array-type ultrasonic probe 50 in which the piezoelectric elements 51 are arranged in at least one row generates harmonic vibration (see FIG. 2). Due to the generation of the harmonics, energy is also distributed to the harmonic components of the array-type ultrasonic probe 50, so that energy loss of the fundamental frequency component is caused and the sensitivity is reduced.
Further, in the array-type ultrasonic probe 50, the transmission of the harmonic component causes disturbance in a transmission sound field formed by electronic focusing for electronically focusing the ultrasonic waves, thereby causing an artifact (virtual image). ), Or the accuracy of the ultrasonic beam synthesis result at the time of reception is reduced.
For this reason, the resolution of the ultrasonic diagnostic image is reduced.

On the other hand, the piezoelectric element 51 has a width W versus a thickness T.
When (w / t) is 0.6 to 0.8, the electromechanical conversion efficiency is improved, but a lateral vibration mode is generated. For this reason, the same trouble as the above-described harmonic component occurs, and at the same time, the crosstalk and the pulse width increase due to the radial vibration, and the resolution of the ultrasonic diagnostic image decreases when the image is formed. 3). Therefore, the piezoelectric element 51
It is necessary that the shape has a high electromechanical conversion efficiency and suppresses generation of unnecessary vibration modes.

The present invention has been made in view of the above circumstances, has a high efficiency of electromechanical conversion, has a piezoelectric element having an optimal shape which suppresses generation of unnecessary vibration modes, and can improve image resolution. It is an object to provide an ultrasonic probe.

[0011]

In order to achieve the above object, the present invention provides a plurality of piezoelectric elements for generating ultrasonic waves and transmitting and receiving the ultrasonic waves, and a plurality of piezoelectric elements located on an acoustic radiation surface side of the plurality of piezoelectric elements. And, an acoustic matching layer for radiating ultrasonic waves generated from the plurality of piezoelectric elements, and a back load member that is located on the back side of the plurality of piezoelectric elements and absorbs unnecessary ultrasonic waves,
In an ultrasonic probe in which at least the plurality of piezoelectric elements are arranged in one row, a thickness t of the piezoelectric element in the acoustic radiation axis direction and a width W of the piezoelectric element in the arrangement direction are provided.
Is set to 0.3 to 0.5.
With this configuration, the electromechanical conversion efficiency is high, and the piezoelectric element has an optimal shape that suppresses the occurrence of unnecessary vibration modes.
An ultrasonic probe capable of improving image resolution is realized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIGS. 1 to 4 relate to a first embodiment of the present invention, and FIG. 1 is a configuration diagram showing an ultrasonic probe according to the first embodiment of the present invention. FIG. 1A is a schematic perspective view showing the configuration of the ultrasonic probe, FIG. 1B is a side sectional view of FIG. 1A, and FIG. 1C is the piezoelectric element of FIG. FIG. 2 shows the operation of the first embodiment of the present invention, and shows the ratio (w) between the thickness t of the piezoelectric element and the width W.
FIG. 2A is a first graph showing impedance characteristics when w / t = 0.2, and FIG. 2B is a graph showing impedance characteristics at w / t = 0.2.
3 is a graph showing impedance characteristics in FIG.
FIG. 2C is a graph showing impedance characteristics at w / t = 0.6, FIG. 2D is a graph showing impedance characteristics at w / t = 0.6, and FIG. 3 is a first embodiment of the present invention. And the impedance characteristic is expressed by changing the ratio (w / t) of the thickness t of the piezoelectric element to the width W.
3A is a graph showing the vicinity of a fundamental resonance point at w / t = 0.5, and FIG. 3B is a graph showing w / t =
FIG. 3 is a graph showing the vicinity of the fundamental resonance point at 0.6, and FIG.
(C) is a graph showing the vicinity of the fundamental resonance point at w / t = 0.8, and FIG. 4 shows the operation of the first embodiment of the present invention. FIG. 4 is a graph showing the echo waveform of the ultrasonic probe while changing w / t).
4A is a graph showing an echo waveform of the ultrasonic probe at w / t = 0.2, FIG. 4B is a graph showing an echo waveform of the ultrasonic probe at w / t = 0.25, FIG.
4C is a graph showing an echo waveform of the ultrasonic probe at w / t = 0.3, and FIG. 4D is a graph showing an echo waveform of the ultrasonic probe at w / t = 0.5. is there.

As shown in FIG. 1, an ultrasonic probe 1 according to a first embodiment of the present invention generates a plurality of piezoelectric elements 2 for generating ultrasonic waves and transmitting and receiving the ultrasonic waves, Element 2
An acoustic matching layer 3 for emitting ultrasonic waves generated from the plurality of piezoelectric elements 2 and an acoustic lens 4 located on the acoustic emitting surface side of the acoustic matching layer 3.
A backing material 5 located on the back side of the plurality of piezoelectric elements 2 and serving as a back load material for absorbing unnecessary ultrasonic waves;
And an array type ultrasonic probe configured by arranging at least the plurality of piezoelectric elements 2 in one dimension.

The piezoelectric element 2 is made of, for example, soft lead zirconate titanate Pb (Zr, T
i) It is made of PZT piezoelectric ceramics such as O3. The acoustic lens 4 is formed from a silicone resin. The acoustic matching layer 3 is, for example, a first acoustic matching layer 3a formed of an epoxy resin using alumina as a filler on the acoustic radiation surface side of the piezoelectric element 2 and on the acoustic radiation surface side of the first acoustic matching layer 3a. The second acoustic matching layer 3b is made of an epoxy resin alone. The backing material 5 is formed of urethane using alumina as a filler. The signal line side of the piezoelectric element 2 is connected to the flexible printed circuit board 6 on which the pattern 6a is formed.
The grounds on the first and second acoustic matching layers 3a and 3b are connected by soldering or conductive resin using a conductive wire 7 or foil as a common electrode, and are covered with a protective resin 8.

The 3 MHz array type (linear array) probe of the present invention is manufactured by the following method.
The first acoustic matching layer 3a (the acoustic impedance is 7.5
A thin plate having a thickness of about 250 μm (about MRayl) is ground.
Next, one side of the first acoustic matching layer 3a is masked with a tape or the like, and a second acoustic matching layer 3b is formed to a thickness of 190 μm on the unmasked side. Next, the piezoelectric element 2 of about 500 μm is fixed to the first acoustic matching layer 3a with an adhesive, and the flexible printed board 6 is joined to the piezoelectric element 2 by soldering. Thereafter, the backing material 5 is cast-bonded to the back side of the plurality of piezoelectric elements 2 and then fixed to the base with wax or fixed with tape. And
In this state, cutting is performed from the piezoelectric element 2 side to form an array type vibrator.

The cutting method is performed by using a precision cutting machine.
Cutting is performed at a pitch of 0.3 mm using a blade having a thickness of μm. At this time, the ratio (w / t) of the thickness t of one piezoelectric element 2 in the acoustic radiation axis direction to the width W of the piezoelectric element 2 in the arrangement direction is w / t = 0.48. It is.

After cutting, a common GND is connected to the surface electrode on the acoustic matching layer 3 side of the piezoelectric element 2 using a lead wire and solder.
Electrodes. Finally, the acoustic lens 4 is formed of a silicone resin to form a transducer portion.

In the ultrasonic probe 1 configured as described above, a drive pulse having a voltage of, for example, several tens to several hundreds of volts is applied to the piezoelectric element 2 from a drive circuit (not shown). Then, the piezoelectric element 2 to which the driving pulse is applied is rapidly deformed by the inverse piezoelectric effect. The ultrasonic probe 1 transmits an ultrasonic pulse by radiating an ultrasonic pulse excited by deformation of the piezoelectric element 2 through the acoustic matching layer 3 and the acoustic lens 4. ing.

The ultrasonic pulse transmitted from the ultrasonic probe 1 is reflected from an object, and then passes through the acoustic lens 4 and the first and second acoustic matching layers 3a and 3b to form the piezoelectric element. 2, and the piezoelectric element 2 is mechanically vibrated. In addition, as an object reflecting the ultrasonic pulse,
For medical use, it is an interface between tissues in the body, and for destructive inspection, it is a discontinuous portion such as a scratch inside the measured object.

The piezoelectric element 2 mechanically vibrated by the re-entered ultrasonic pulse converts the mechanical vibration into an electric signal by the piezoelectric effect, and then transmits the electric signal to an observation device (not shown). The observation device processes the electric signal,
The image is displayed on the monitor as an ultrasonic diagnostic image.

Here, when the ratio (w / t) of the thickness t of the piezoelectric element 2 in the acoustic radiation axis direction to the width W of the piezoelectric element 2 in the arrangement direction is changed, FIG. 2 and FIG. The impedance characteristic as shown is obtained.

FIGS. 2 and 3 are graphs showing impedance characteristics (acoustic impedance and phase with respect to frequency) by changing the ratio (w / t) between the thickness t of the piezoelectric element 2 and the width W. FIG. FIG. 2A is a graph showing impedance characteristics at w / t = 0.2, and FIG. 2B is a graph showing w / t = 0.
3 is a graph showing impedance characteristics in FIG.
FIG. 2C is a graph showing impedance characteristics at w / t = 0.5, and FIG. 2D is a graph showing impedance characteristics at w / t = 0.6. FIG. 3 (a)
Is a graph showing the vicinity of the basic resonance point at w / t = 0.5, FIG. 3B is a graph showing the vicinity of the basic resonance point at w / t = 0.6, and FIG. 3C is w / t = 0. 8 is a graph showing the vicinity of the fundamental resonance point at 0.8. The phase is a phase difference between a current signal and a voltage signal of a drive signal for driving the piezoelectric element 2. At the point where the phase difference becomes zero, the magnitude of the acoustic impedance becomes minimum, and all the electric energy supplied to the piezoelectric element 2 is converted into vibration energy.

When w / t <0.3, the vibration mode in the horizontal direction is small, but the higher-order vibration in the thickness direction is large. More specifically, when w / t = 0.2, the third and other higher harmonics increase, and as the w / t ratio increases, the vibration of the higher-order mode decreases.

On the other hand, when w / t> 0.6, a horizontal vibration component perpendicular to the polarization axis of the piezoelectric element 2 occurs. Therefore, when an ultrasonic probe is configured using the piezoelectric element 2 with w / t> 0.6, an unnecessary vibration mode is generated. Therefore, the same problems as those of the above-described harmonic components occur, and at the same time, crosstalk and an increase in pulse width occur.

FIG. 4 uses a 5 MHz piezoelectric element 2 produced in the same manner, and uses a stainless steel flat reflector by changing the ratio (w / t) of the thickness t of the piezoelectric element 2 to the width W. 6 is a graph showing an echo waveform of the ultrasonic probe measured by the above method. 4A shows an echo waveform at w / t = 0.2, FIG. 4B shows an echo waveform at w / t = 0.25, and FIG. 4C shows w / t = 0. 3 shows an echo waveform, and FIG. 4D shows an echo waveform at w / t = 0.5.

For example, when w / t <0.25 as shown in FIGS. 4A and 4B, a large harmonic component appears in the echo wave, and the waveform is disturbed. It is difficult to completely remove the harmonic components even by using a band-pass filter. On the other hand, as shown in FIGS. 4C and 4D, when w / t = 0.3 and w / t = 0.5, the harmonic component appearing in the echo wave becomes very small,
The waveform is not disturbed.

As a result, in order to efficiently vibrate the piezoelectric element 2 and to suppress the higher-order mode and the lateral vibration, the thickness t of the piezoelectric element 2 in the acoustic radiation axis direction and the thickness t of the piezoelectric element 2 It can be seen that the ratio (w / t) to the width W in the arrangement direction needs to be 0.3 ≦ w / t ≦ 0.5.

In the present embodiment, the ratio (w / t) of the thickness t of the piezoelectric element 2 in the acoustic radiation axis direction to the width W of the piezoelectric element 2 in the arrangement direction is 0.3 to 0.5. Furthermore, in the case of a soft PZT-based material, (w / t) is desirably set to 0.4 to 0.5 in order to further suppress higher-order mode vibration.

Thus, the w / t ratio of the piezoelectric element 2 is set to 0.1.
By setting the optimum value to 3 to 0.5, and more preferably to 0.4 to 0.5, the generation of unnecessary vibration modes such as a higher-order vibration mode and a lateral vibration mode is suppressed, and imaging is performed. In addition, since a simple filter may be used, and the energy loss is small, the high-sensitivity piezoelectric element 2 can be realized at low cost.

In this embodiment, an array type ultrasonic probe (linear array) arranged linearly has been described. However, a convex type ultrasonic probe in which a plurality of piezoelectric elements 2 are curved in a divided state. The present invention may be applied to a probe.

(Second Embodiment) FIGS. 5 and 6 relate to a second embodiment of the present invention, and FIG. 5 is a schematic diagram showing an ultrasonic probe according to a second embodiment of the present invention. FIG. 6 is a sectional view and FIG.
It is a schematic sectional drawing which shows the ultrasonic probe which shows the modification of.
In the first embodiment, the ultrasonic probe is formed by forming the first acoustic matching layer 3a with an epoxy resin using alumina as a filler. In the second embodiment, however, the first acoustic matching layer 3a is formed of the first acoustic matching layer 3a. The matching layer 3a is formed of carbon to form an ultrasonic probe. The other configuration is substantially the same as that of the first embodiment, and therefore the description thereof is omitted, and the same configuration is denoted by the same reference numeral.

As shown in FIG. 5, the ultrasonic probe 10 according to the second embodiment has a composite carbon material containing ultrafine particles of silicon carbide SiC and boron carbide B4C on the acoustic emission surface side of the piezoelectric element 2. It has the 1st acoustic matching layer 11 formed from.

The 5 MHz array type (linear array) probe of the present invention is manufactured by the following method. First, a carbon composite material containing ultrafine particles of silicon carbide SiC and boron carbide B4C to be the first acoustic matching layer 11 is ground to a thickness of 200 μm. Here, the carbon composite material includes graphite (carbon) containing fine particles of SiC and B4C. In this carbon composite material, the ceramic fine powder mixed in a wedge-like manner between the graphite (carbon) particles suppresses the growth of microcracks, and has significantly improved strength as compared with graphite. For this reason, this carbon composite material has a higher frequency of 10 MHz or more (10 MHz or more).
Even when processing a thin material (0 μm or less), it can be processed relatively easily by using a double-sided lapping machine, or by attaching and grinding and polishing a base material using wax, a water-soluble adhesive, or the like.

The carbon composite material used in the present embodiment is composed of 6 wt% of SiC having an average particle size of 0.5 μm and 9 wt% of B4C having an average particle size of 5 μm, and zirconium boride. Is blended at 4 wt%. The acoustic impedance of this carbon composite material is 8.5 MRa
yl.

Next, the first carbon composite material is used.
One side of the acoustic matching layer 11 is masked with a tape or the like, and an unmasked surface is formed of an epoxy resin.
A second acoustic matching layer 3b is formed by forming a 00 μm resin layer. Next, the piezoelectric element 2 of about 300 μm is fixed to the first acoustic matching layer 11 using an adhesive, and the flexible printed circuit board 6 provided with the pattern is joined to the piezoelectric element 2 by soldering.

Thereafter, it is fixed to the base with wax or fixed with tape. Then, in this state, cutting is performed from the piezoelectric element 2 side to the middle of the second acoustic matching layer 3b to form an arrayed vibrator. As for the cutting method, a blade having a thickness of 30 μm is used at a pitch of 130 μm using a precision cutting machine. At this time, the ratio (w / t) of the thickness t of one piezoelectric element 2 in the acoustic radiation axis direction to the width W of the piezoelectric element 2 in the arrangement direction is w / t = 0.33. It is. Note that the arrayed vibrator of the present embodiment has two elements connected to one pattern, and has a so-called sub dice configuration.

Next, a backing material 5 formed of an epoxy resin using alumina as a back surface load material is cast-bonded to the back surface of the piezoelectric element 2, and the side surface of the first acoustic matching layer 11 is cleaned. I do. Then, the flexible printed circuit board 12 having the solid electrode is joined to the surface electrode on the acoustic matching layer 3 side of the piezoelectric element 2 by a conductive adhesive to form a common G board.
ND electrode. Finally, the acoustic lens 4 is formed of a silicone resin to form a transducer portion.

The ultrasonic probe 10 configured as above is
Even if the configuration of the transducer is changed, including the first and second acoustic matching layers 11 and 3b, as in the first embodiment, when w / t = 0.25 or less, harmonics including the third order are obtained. And the higher the w / t ratio, the smaller the vibration of the higher-order mode.

The manufactured ultrasonic probe 10 has w
When /t=0.25 or less, a large harmonic component appears in the echo wave, and it is difficult to completely remove even a bandpass filter. Further, as described with reference to FIGS. 2 and 3, when the w / t ratio is 0.6 or more, a vibration component in a horizontal direction perpendicular to the polarization axis enters, so that when the ultrasonic probe is used, Unnecessary vibration modes appear. For this reason, a field failure occurs as in the case of the above-described harmonic components, and crosstalk and an increase in pulse width occur, so that image accuracy is reduced when an image is formed.

As a result, as in the first embodiment, in order to vibrate the piezoelectric element 2 efficiently and suppress higher-order modes and lateral vibrations, the direction of the acoustic radiation axis of the piezoelectric element 2 must be adjusted. It can be seen that the ratio (w / t) between the thickness t and the width W in the arrangement direction of the piezoelectric elements 2 needs to be 0.3 ≦ w / t ≦ 0.5.

In this embodiment, similarly to the first embodiment, the thickness t of the piezoelectric element 2 in the direction of the acoustic radiation axis,
Ratio (w / t) with the width W in the arrangement direction of the piezoelectric elements 2
In the case of a soft PZT material, (w / t) is desirably set to 0.4 to 0.5 in order to further suppress higher-order mode vibration. . Thus, the ultrasonic probe 10 according to the second embodiment can obtain the same effect as the ultrasonic probe 1 according to the first embodiment.

Since the first acoustic matching layer 11 made of the carbon composite material has conductivity, it is used not only as an acoustic matching layer but also as an electrode from the piezoelectric element 2. be able to. In the present embodiment, the piezoelectric element 2 and the first acoustic matching layer 11 are electrically connected via a thin adhesive layer, and by connecting the first acoustic matching layer 11, the piezoelectric element 2 after cutting is cut off. A common electrode is formed. Further, the side surface of the first acoustic matching layer 11 has a larger area that can be connected than the exposed side electrode of the piezoelectric element 2, and the reliability of the connection is improved. Further, in the configuration in which the connection is made from the side surface of the first acoustic matching layer 11, it is possible to increase the acoustic radiation area with respect to the size of the transducer portion, and it is easy to reduce the size.

Although not shown in FIG. 5, it is necessary to insulate the signal electrode side of the piezoelectric element 2 from the flexible printed circuit board 12 serving as a common GND electrode. As the method, the piezoelectric element 2 of the flexible printed board 12 itself is used.
And a method of arranging polyimide which is an insulator in a portion adjacent to the above. As other methods, there is a method in which an electrode of the piezoelectric element 2 is provided not with a full-surface electrode but in a region adjacent to the flexible printed board 12 in advance without an electrode,
It is also possible to insulate in a similar manner by sealing the exposed signal electrode of the piezoelectric element 2 with resin.

The ultrasonic probe may be configured as shown in FIG. FIG. 6 is a schematic sectional view showing an ultrasonic probe showing a modification of FIG. The ultrasonic probe 20 is shown in FIG.
As described above, the first and second acoustic matching layers 11 and 3b are stacked, and the piezoelectric element 21 slightly smaller than the first and second acoustic matching layers 11 and 3b is joined.

Thereafter, it is fixed to the base with wax or fixed with tape. Then, in this state, cutting is performed from the piezoelectric element 21 side to the middle of the second acoustic matching layer 3b,
An array type vibrator is formed in which the w / t ratio of the piezoelectric element 21 is set to an optimum value of 0.3 to 0.5, more preferably 0.4 to 0.5.

After the cutting, the divided first acoustic matching layer 11 is connected with the copper wire 7 and the conductive resin 22, and the signal line side is formed by a thin wire 24 from a substantially distal end of a glass epoxy substrate 23 having a pattern formed on both sides. Each piezoelectric element 2 is connected by soldering.

Then, a backing material 5 is filled in grooves formed by providing frames (not shown) at both ends of the first acoustic matching layer 11 to form a back load material, and the acoustic lens 4 is formed of silicone resin. To produce a transducer portion.

The ultrasonic probe 20 constructed as described above
Can obtain the same effects as those of the first and second embodiments, and can reduce the thickness of the first acoustic matching layer 11 by increasing the frequency.
When connection is difficult from the side of the above, workability is good and yield can be improved.

In this modification, the first and second acoustic matching layers 11 and 3b are laminated, and the first and second acoustic matching layers 1 and 3b are stacked.
After forming a laminate in which the piezoelectric elements 21 slightly smaller than 1, 3b are joined, when cutting, a cut is made to a depth such that a part thereof reaches the first acoustic matching layer 11, so that an area for ground wiring is formed. To form Thereafter, dicing is performed to form an array-type element, and a common electrode is formed by connecting the wires 9 with the conductive resin 22, so that an ultrasonic probe can be manufactured. After bonding, wiring is performed at the cut portions in the carbon material, so that there is no conduction failure due to the adhesive or the like, and the yield and reliability are improved.

Further, in the present embodiment, the first acoustic matching layer 11 is completely cut. However, each cut piezoelectric element can be cut off slightly in the depth direction or by providing an uncut portion at the end. It is not necessary to connect the common GND, and an inexpensive and highly reliable device can be manufactured. Further, the first acoustic matching layer 1
80% in the thickness direction regardless of the application of 1
By cutting as described above, the piezoelectric element 21 having high electromechanical conversion efficiency can be manufactured.

Since the cut piezoelectric element 21 is connected to an adjacent element, there is a problem of crosstalk. However, since the common GND electrode side is left uncut, no wiring is required, and the transducer can be manufactured at low cost. In addition, only the sub-die portion is
By cutting in the middle of 1 or the middle of the first acoustic matching layer 11 which is a conductive acoustic matching layer, crosstalk can be suppressed and the reliability of wiring can be improved.

As in the first embodiment, a convex ultrasonic probe can be manufactured by bending the piezoelectric element 21 while being divided into a plurality of piezoelectric elements 21.

The configuration in each of the first and second embodiments and the modifications described above may have various modifications. Representative examples are shown below. The piezoelectric element 2
A similar effect can be obtained with a piezoelectric element such as a piezoelectric single crystal in addition to a PMN-based piezoelectric ceramic, such as a PZT-based piezoelectric ceramic obtained by general sintering.

The method of manufacturing the probe is not limited to the above embodiment. For example, the second acoustic matching layer 3b is ground and formed to a predetermined thickness with an epoxy resin, and the first acoustic matching layer is formed. The layer 3a is cast, ground, and formed with an epoxy resin containing alumina filler, and after fixing the piezoelectric element 2 with an adhesive,
The w / t ratio may be set to 0.3 to 0.5 by dicing from the piezoelectric element 2 side to the middle of the second acoustic matching layer 3b.

As described above, after forming the acoustic matching layer 3 which is harder than the backing material 5 which is the back load material, the acoustic matching layer 3 is cut from the piezoelectric element 2 side, thereby increasing the accuracy in the depth direction,
During the cutting, the displacement of the piezoelectric element 2 is small, and it is unlikely that the piezoelectric element 2 is broken and the groove width is stabilized. For this reason, a high-frequency transducer having a small width of the piezoelectric element 2 or a downsized transducer can be manufactured with high yield.

As described with reference to FIG. 6, a frame (not shown) is provided after wiring on the signal side, and a mixture of an epoxy resin having flexibility after curing and an insulating powder such as alumina or zirconia is provided in the frame. By casting and forming the backing material 5 as a back load material, a stable probe can be formed without the need for an adhesive layer and with a small variation in reflection at the interface.

It is to be noted that each configuration of the embodiment of the present invention described here can be variously modified and changed. Further, the present invention is not limited to only the above-described embodiment, and the width W of the piezoelectric element 2 in the arrangement direction is defined as the width W orthogonal to the acoustic radiation axis of the piezoelectric element 2. 2, the ratio of the thickness t in the direction of the acoustic radiation axis to the width W orthogonal to the acoustic radiation axis of the piezoelectric element 2 is 0.3 to 0.3.
The ultrasonic probe may be configured as 0.5, more preferably 0.4 to 0.5.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[Supplementary Notes] (Supplementary note 1) A plurality of piezoelectric elements that generate ultrasonic waves and transmit and receive the ultrasonic waves, and are located on the sound radiation surface side of the plurality of piezoelectric elements and are generated from the plurality of piezoelectric elements. Acoustic matching layer for emitting ultrasonic waves, and a back load material that is located on the back side of the plurality of piezoelectric elements and absorbs unnecessary ultrasonic waves,
In an ultrasonic probe in which at least the plurality of piezoelectric elements are arranged in one row, a thickness t of the piezoelectric element in the acoustic radiation axis direction and a width W of the piezoelectric element in the arrangement direction are provided.
The ultrasonic probe characterized in that the ratio of 0.3 to 0.5.

(Additional Item 2) The ultrasonic probe according to Additional Item 1, wherein the piezoelectric element is formed from a lead zirconate titanate Pb (Zr, Ti) O3 material.

(Additional Item 3) The piezoelectric element or at least one acoustic matching layer joined to the piezoelectric element is divided while leaving a part of the piezoelectric element or the acoustic matching layer in the acoustic radiation axis direction. 3. The ultrasonic probe according to claim 1 or 2, wherein

(Additional Item 4) A plurality of piezoelectric elements for generating ultrasonic waves and transmitting and receiving the ultrasonic waves, and the ultrasonic waves generated from the plurality of piezoelectric elements, which are located on the acoustic radiation surface side of the plurality of piezoelectric elements. An acoustic matching layer for radiating light, and a back load member located on the back side of the plurality of piezoelectric elements and absorbing unnecessary ultrasonic waves, wherein at least the plurality of piezoelectric elements are arranged in one row. In the acoustic probe, a ratio of a thickness t of the piezoelectric element in the acoustic radiation axis direction to a width W orthogonal to the acoustic radiation axis direction of the piezoelectric element is 0.3 to 0.5. Ultrasonic probe.

(Additional Item 5) The ultrasonic probe according to additional item 4, wherein the piezoelectric element is formed from a lead zirconate titanate Pb (Zr, Ti) O3 material.

(Supplementary Note 6) The piezoelectric element or at least one acoustic matching layer joined to the piezoelectric element is divided while leaving a part of the piezoelectric element or the acoustic matching layer in the acoustic radiation axis direction. 6. The ultrasonic probe according to claim 4 or 5, wherein

[0065]

As described above, according to the present invention, an electromechanical conversion efficiency is high, a piezoelectric element having an optimal shape which suppresses generation of unnecessary vibration modes is provided, and an image resolution can be improved. An acoustic probe can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an ultrasonic probe according to a first embodiment of the present invention.

FIG. 2 is a first graph showing the operation of the first embodiment of the present invention and showing impedance characteristics by changing the ratio (w / t) between the thickness t and the width W of the piezoelectric element.

FIG. 3 is a second graph showing the operation of the first embodiment of the present invention and showing impedance characteristics by changing the ratio (w / t) between the thickness t of the piezoelectric element and the width W.

FIG. 4 is a graph showing the operation of the first embodiment of the present invention, and showing the echo waveform of the ultrasonic probe by changing the ratio (w / t) between the thickness t of the piezoelectric element and the width W.

FIG. 5 is a schematic sectional view showing an ultrasonic probe according to a second embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing an ultrasonic probe showing a modification of FIG. 5;

FIG. 7 is a configuration diagram showing a conventional array type ultrasonic probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe (array type ultrasonic probe) 2 ... Piezoelectric element 3 ... Acoustic matching layer 3a ... 1st acoustic matching layer 3b ... 2nd acoustic matching layer 4 ... Acoustic lens 5 ... Backing material (back load) Material)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04R 1/34 330 H04R 1/34 330Z 17/00 332A 17/00 332 H01L 41/08 J (72) Invention Takuya Imahashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Inventor Akiko Mizunuma 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term inside Olympus Optical Co., Ltd. ) 2G047 EA05 GB02 GB12 4C301 EE06 GB03 5D019 AA11 AA21 BB02 BB18 FF04 FF05 GG01 GG03 GG05 GG06 5D107 AA03 AA16 BB07 BB09 CC01 CC12

Claims (1)

[Claims] 1. A plurality of piezoelectric elements for generating ultrasonic waves and transmitting and receiving the ultrasonic waves, and radiating the ultrasonic waves generated from the plurality of piezoelectric elements, the ultrasonic elements being located on an acoustic emission surface side of the plurality of piezoelectric elements. An acoustic matching layer for, and a back load member located on the back side of the plurality of piezoelectric elements and absorbing unnecessary ultrasonic waves,
In an ultrasonic probe in which at least the plurality of piezoelectric elements are arranged in one row, a ratio of a thickness t of the piezoelectric element in an acoustic radiation axis direction to a width W of the piezoelectric element in an arrangement direction is defined as: An ultrasonic probe characterized by being 0.3 to 0.5.