JP2004056352A - Ultrasonic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic transducer formed by stacking piezoelectric vibrators adopting an electrode structure attaining the layout of a ground lead wire and a signal input output wire whereby an effective area of ultrasonic wave radiation can widely be ensured and an area of interlinked magnetic flux is decreased. <P>SOLUTION: The ultrasonic transducer is characterized in the configuration to include: a vibrator 1 by forming an even number of piezoelectric vibrators 1-1, 1-2 having electrodes on both sides to have a layered structure and provided with an even number of electrodes; a non-piezoelectric acoustic matching layer 2 placed on an upper face of the vibrator and having an electrode 3b on its surface; a packing member 7 fixed to the lower face of the vibrator; and the ground lead wire 5 and the signal input output lead wire 6. An even number of electrodes and the odd number of electrodes 3a, 4a, 4b of the vibrator 1 and the electrode 3b of the acoustic matching layer are alternately connected to form two electrode pairs. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic transducer using a piezoelectric vibrator used for an ultrasonic diagnostic apparatus and an ultrasonic flaw detector.
[0002]
[Prior art]
In an ultrasonic diagnostic apparatus or an ultrasonic inspection apparatus, an ultrasonic signal is transmitted by an ultrasonic transducer equipped with a piezoelectric vibrator, and a part of the ultrasonic signal is transmitted to a boundary surface such as a defect of a tissue or a living body. The reflected ultrasonic signal reflected by the piezoelectric vibrator is received again by the piezoelectric vibrator, and this signal is imaged.
[0003]
3A and 3B are cross-sectional views schematically showing the structure of a conventional ultrasonic transducer. FIG. 3A shows a case where the piezoelectric vibrator has a single layer, and FIG. Show.
[0004]
The basic configuration of a conventional ultrasonic transducer is such that, as shown in FIG. 3A when the piezoelectric vibrator has a single layer, electrode layers 33 and 34 parallel to the piezoelectric vibrator 31 are provided. An acoustic matching layer 32 is formed on the ultrasonic wave transmitting / receiving surface (upper surface) of the element 31. Further, an acoustic lens for acoustic focusing may be formed on the acoustic matching layer 32.
[0005]
Further, a backing material 37 for fixing the piezoelectric vibrator by bonding or the like and for absorbing the ultrasonic wave radiated backward is attached to the surface of the piezoelectric vibrator 31 facing the acoustic matching layer on the electrode 34 side. Is provided.
[0006]
In a medical ultrasonic transducer such as an ultrasonic diagnostic apparatus, a ground lead wire 35 is connected to an electrode 33 on the acoustic matching layer 32 side in contact with a living body in consideration of electrical safety, and a signal voltage is input to a pair of electrodes 34. A signal input / output lead wire 36 of the flexible printed wiring to be output is connected.
[0007]
On the other hand, in order to improve the electrical matching between the ultrasonic transducer and the transmission / reception circuit, there is a method in which the piezoelectric vibrator has a laminated structure, the capacitance value is increased, and the electric impedance is reduced. When the piezoelectric vibrator according to this method has a laminated structure, the basic structure is the same as the case of a single layer as shown in FIG. 3B, but the piezoelectric vibrators 31a and 31b are The electrodes 33 and 34 are formed by firing, and are laminated and joined by a conductive adhesive to form a laminated structure. In order to maintain the connection strength between the ground lead wire 35 and the signal input / output lead wire 36, the connection electrode 34a is formed in order to solder the connection portion in a planar shape.
[0008]
In the laminated piezoelectric vibrators 31a and 31b, the electrode 33 on the acoustic matching layer 32 side that is in contact with the living body is provided to be extended on the outer side surface of the piezoelectric vibrators 31a and 31b, and the electrode on the surface that is in contact with the backing material 37 is provided. A ground lead wire 35 is connected to 33a by soldering. Further, the electrode 34 sandwiched between the stacked piezoelectric vibrators 31a and 31b does not have a soldering connection area in a planar manner other than being connected on the surface in contact with the backing material 37, and originally becomes the electrode 33a. A turn-in electrode 34a is formed in the portion, and a signal input / output lead line 36 of a flexible printed wiring is connected thereto. Since a high voltage is applied to both electrodes, a withstand voltage gap 39a is provided between the electrode 33a and the electrode 34a.
[0009]
Since two lead wires are drawn out from the lower surface of the piezoelectric vibrator, the ground common lead wire 35 and the signal input / output lead wire 36 are arranged on both sides of the backing material 77, respectively.
[0010]
[Problems to be solved by the invention]
In the above-described vibrator body having a stacked structure of a plurality of piezoelectric vibrators, two electrodes are formed on one surface of the vibrator. Since one of the two electrodes thus formed has a structure of a turn-in electrode extending from the opposing surface, a voltage is not applied to the portion 38 of FIG. It does not function as a vibrator and does not participate in transmission and reception of ultrasonic signals. In addition, in order to provide two electrodes on the same surface, it is necessary to provide an electrode gap having an interval enough to withstand a high-voltage driving voltage, and the pressure-resistant gaps 39a and 39b do not operate as vibrators. The range becomes w shown in the figure, and the substantial ultrasonic radiation area is further reduced. In particular, in the case of a sector ultrasonic transducer for the heart of a medical ultrasonic diagnostic apparatus, this ultrasonic transducer is attached between the ribs to observe the heartbeat, but the external shape of the ultrasonic transducer is limited in order to fit the living body. In addition, when the effective range of the piezoelectric vibrator is narrowed as described above, a sufficient effective radiation aperture cannot be obtained, which has been a serious problem.
[0011]
In addition, since the grounding lead wire and the signal input / output lead wire are respectively drawn out from both side surfaces of the backing material, the area of the interlinkage magnetic flux formed by being surrounded by these lead wires is increased, and the adjacent magnetic flux from other vibrators is increased. It is susceptible to channel crosstalk and noise from electronic equipment, which may hinder the use of the continuous wave blood flow velocity display mode.
[0012]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and can provide a wide effective area for ultrasonic radiation and reduce a flux linkage area and a ground lead and a signal input / output lead. It is an object of the present invention to provide an ultrasonic transducer in which a piezoelectric vibrator having an electrode structure capable of disposing the piezoelectric transducers is laminated.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to claim 1 of the present invention, an even number of piezoelectric vibrators having electrodes on both surfaces are formed in a laminated structure, and a vibrator body having an odd number of electrodes is provided. An acoustic matching layer disposed on the upper surface of the vibrator body and provided with electrodes on the surface, a backing material fixed to the lower surface of the vibrator body, a ground lead and a signal input / output lead; An ultrasonic transducer is provided, wherein an odd number of electrodes including an odd number of electrodes of the body and an electrode of the acoustic matching layer are alternately connected to form two sets of electrodes.
[0014]
Further, according to claim 2 of the present invention, in the two electrode sets, a ground lead is connected to a first electrode set including the electrodes of the acoustic matching layer, and a second electrode set in another electrode set is provided. And a signal input / output lead wire connected to the ultrasonic transducer.
[0015]
Furthermore, according to claim 3 of the present invention, the ground lead connected to the first set of electrodes and the signal input / output lead connected to the second set of electrodes are connected to the resonator having the laminated structure. An ultrasonic transducer is provided, which is arranged close to one another on the same side of a body and a backing material holding the vibrator body.
[0016]
Further, according to claim 4 of the present invention, the ground lead connected to the first electrode set is shared with a ground lead connected to another built-in vibrator having a laminated structure. A signal input / output lead connected to the conductor and connected to the second electrode set is separated from a signal input / output lead connected to another built-in vibrator body having a built-in structure. Provided is an ultrasonic transducer which is connected and supplied by printed wiring.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view schematically illustrating the ultrasonic transducer of the embodiment, as an example, in which a piezoelectric vibrator has a two-layer laminated structure. FIG. 1A is a cross-sectional view of an ultrasonic transducer, and FIG. 1B is a cross-sectional view of each of a plurality of piezoelectric vibrators and an acoustic matching layer of a member constituting the present embodiment.
[0019]
As shown in FIG. 1A, the ultrasonic transducer according to the embodiment includes two piezoelectric vibrators 1-1 and 1-2 made of barium titanate-based or lead zirconate-based piezoelectric ceramics whose electrodes are fired. Forms the vibrator body 1 having a two-layer laminated structure with the polarization directions E reversed to each other and the electrode 3a corresponding to the ground interposed therebetween. An electrode 4a corresponding to signal input / output is provided on the upper surface of the piezoelectric vibrator 1-1 of the vibrator body 1, and an electrode 4a corresponding to signal input / output is provided on a lower surface of the piezoelectric vibrator 1-2. 4b.
[0020]
The back end surface of the acoustic matching layer 2 having the electrode 3b on one end surface in advance contacts the electrode 4b of one of the two piezoelectric vibrators 1-1, and the acoustic matching layer 2 is fixed.
[0021]
The electrode 3c and the electrode 4c are provided on the respective side surfaces of the piezoelectric vibrators 1-1 and 1-2 or the acoustic matching layer 2, and the electrode 3a and the electrode 3b and the electrode 4a and the electrode 4b are connected and connected respectively. You.
[0022]
Further, the tip of a signal input / output lead wire 6 of a flexible printed wiring for inputting / outputting a signal is connected to an electrode 4a on the lower surface of the piezoelectric vibrator 1-2 by soldering or a conductive adhesive. The piezoelectric vibrator 1-2 is bonded to the backing material 7 so as to lay the connection portion and the electrode 4a.
[0023]
The tip of the ground lead wire 5 connected to the ground is connected to the electrode 3b provided on the acoustic matching layer 2 on the same side as the side surface on which the signal input / output lead wire 6 is arranged. The acoustic lens 8 is bonded to the upper surface of the acoustic matching layer 2 so as to lay the connection portion and the electrode 3b.
[0024]
The laminated piezoelectric vibrators 1-1 and 1-2 and the acoustic matching layer 2 and the electrodes 3a, 3b, 4a and 4b provided thereon are formed as members as shown in FIG. After that, the electrodes are stacked, and the electrodes in contact with each other are adhered to each other with a conductive adhesive to assemble them.
[0025]
In this assembly, in the piezoelectric vibrator 1-2 located at the lowermost layer, a piezoelectric ceramic such as a barium titanate-based or lead zirconate titanate-based (PZT) is formed into a predetermined thickness and shape to cause resonance vibration at a desired frequency. The signal input / output electrode 4a is provided on one surface, for example, the lower surface, the ground electrode 3a is provided on the upper surface of the opposite surface, and withstand voltage gaps 9a and 9b are provided on one side end of each surface. It is formed of an electrode material. In addition, the connection electrode 4c is similarly formed on the right side surface of the piezoelectric vibrator 1-2, for example, using the same silver electrode paste or conductive paint.
[0026]
Similarly, in the middle-layer piezoelectric vibrator 1-1 placed on the upper part of the piezoelectric vibrator 1-2, the piezoelectric ceramic is similarly processed into a predetermined thickness and shape, and one surface in contact with the piezoelectric vibrator 1-2 is grounded. The electrode 3a is formed of an electrode material such as a silver electrode paste, with the signal input / output electrode 4a provided on the upper surface of the facing surface and the withstand voltage gaps 9c and 9d provided on one side end of each surface. The withstand voltage gap 9c is provided at the same position as the withstand voltage gap 9b provided on the corresponding piezoelectric vibrator 1-2. The connection electrode 4c for input / output signals is provided on the side of the piezoelectric vibrator 1-1 on the same side as the connection electrode 4c of the previous piezoelectric vibrator 1-2, and the ground connection electrode 3c is provided on the opposite side. Each of them is formed of a silver electrode paste or a conductive paint.
[0027]
Since the piezoelectric vibrator having the above-described electrode structure does not include a portion of the structure of the spiral electrode, a region W that operates as a piezoelectric vibrator as shown in FIG. Except for both withstand voltage gaps 9, the entire region increases.
[0028]
Further, the acoustic matching layer 2 to be the uppermost layer is made of a non-piezoelectric material and also has heat resistance, for example, cut ceramics or the like, is processed into a predetermined thickness and shape, and a gap of a withstand voltage gap 9e is provided on the lower surface thereof. The signal input / output electrode 4b, the ground electrode 3b on the upper surface facing the same, and the grounding connection electrode 3c on the same side surface as the connection electrode 3c of the lower piezoelectric vibrator 1-1 are respectively connected with silver electrode paste or conductive material. It is formed with a conductive paint. Here, the case of the acoustic matching layer 2 composed of one layer is shown. However, when the acoustic matching layer 2 is composed of two or three layers, the acoustic matching layer 2 is formed after forming two or three matching layers. The signal input / output electrode 4b, the ground electrode 3b, and the connection electrode 3c are formed to obtain two or three acoustic matching layers 2.
[0029]
After firing the ceramics on which the electrodes are formed and fixing the electrodes, the piezoelectric vibrators 1-1 and 1-2 of the piezoelectric ceramics other than the acoustic matching layer 2 have a voltage of about 1 kV / A voltage of mm × (thickness of ceramics) is applied to perform a polarization process, and the resultant is used as the piezoelectric vibrators 1-1 and 1-2 to be laminated and assembled.
[0030]
When the acoustic matching layer 2 is formed of a resin mixed with an acoustic impedance adjusting powder, the signal input / output electrode 4a, the ground electrode 3b, and the connection electrode 3c are formed of a conductive paint and fired. The coating is dried without performing the above steps, and is adhered to the upper portion of the laminated vibrator with a conductive adhesive to assemble.
[0031]
In the above description, after forming each electrode and baking the ultrasonic transducer, a polarization process is performed to bond the piezoelectric ceramics as the piezoelectric vibrators 1-1 and 1-2 for lamination with a conductive adhesive. The procedure for forming the piezoelectric vibrator body 1 having a laminated structure was described above. After forming and firing each electrode, these were adhered to each other with a conductive adhesive, and were applied to the electrodes 3 and 4 at about 1 kV / mm. The ultrasonic transducer of the present embodiment can also be configured by assembling in the procedure of applying the above-mentioned voltage and performing polarization processing to form the piezoelectric vibrator body 1 having a laminated structure.
[0032]
In the array type ultrasonic transducer used in the electronic scanning ultrasonic diagnostic apparatus, the acoustic matching layer 2 and the laminated piezoelectric vibrator 1 are cut by a dicing saw in a plane parallel to the cross section in FIG. Then, the ground lead wire 5 and the signal input / output lead wire 6 are formed while maintaining the connection to the respective target electrodes. In particular, the signal input / output lead wires 6 requiring a large number of signal lines can be suitably constituted by flexible printed wiring.
[0033]
The operation of the ultrasonic transducer of the present embodiment configured as described above will be described.
[0034]
An AC voltage having a resonance frequency of the laminated piezoelectric vibrator 1 is applied to the signal input / output lead 6 with respect to the ground lead 5 shown in FIG. The stacked piezoelectric vibrators 1-1 and 1-2 both vibrate by contracting or expanding in the thickness direction. In this deformation, one surface is fixed to the backing material 7 having a sufficiently large mass, and the amplitude of vibration of the surface on which the electrode 4b is applied is almost four times that of a single-layer piezoelectric vibrator having the same resonance frequency. Become.
[0035]
This vibration propagates through the acoustic matching layer 2 provided on the upper surface of the laminated piezoelectric vibrator body 1. Since the acoustic matching layer 2 is formed with a thickness corresponding to 波長 wavelength of the resonance frequency of the laminated piezoelectric vibrator, the acoustic matching layer 2 can be applied to a medium outside the ultrasonic transducer by a １ ／ wavelength matching effect of wave propagation. The ultrasonic vibration generated in the laminated piezoelectric vibrator body 1 is efficiently propagated and emitted.
[0036]
On the other hand, when the ultrasonic vibration propagates from the outside to the ultrasonic transducer of the present embodiment, the above-described operation is performed reversibly, and the vibration resonance voltage is applied between the electrodes 3 and 4 of the laminated piezoelectric vibrator body 1. Is generated, and can be taken out as a signal voltage between the grounding lead wire 5 and the signal input / output lead wire 6 connected to the respective electrodes and provided on one side of the ultrasonic transducer. Serve as a signal.
[0037]
In the above description, the stacking of two layers has been described. However, FIG. 2 shows another embodiment having an even number of layers, such as four layers and six layers, in which four layers are stacked.
[0038]
In this embodiment, a four-layer stack 21-1 to 21-4 is formed by repeatedly stacking a set of two-layer piezoelectric vibrators 21-1 and 21-2 having the above-described electrode structure. That is, a vibrator body composed of 2n (even number) layers has a piezoelectric vibrator 1-1 and a piezoelectric vibrator 1-2 shown in FIG. The n sets of daughters are stacked, and the connection electrodes 23c and 24c on both sides are connected between the respective stacks. Further, an acoustic matching layer 22 having an electrode 23b on the surface, which has the same form as the acoustic matching layer having an electrode on the surface shown in the uppermost part of FIG. The electrode 23c on the side surface of the laminated vibrator and the electrode 23b on the surface are connected.
[0039]
With respect to the even number of laminated piezoelectric vibrators and acoustic matching layers formed as described above, a ground lead (not shown) is connected to the side end of the electrode 23b of the acoustic matching layer 22 not provided with the connection electrode 23c, Also, a signal input / output lead (not shown) is connected to the end of the electrode 24a of the lowermost vibrator on the same side as the ground lead.
[0040]
Further, a backing material and an acoustic lens (not shown) are fixed to the lowermost vibrator and the acoustic matching layer, respectively, to constitute another embodiment having an even number of laminated piezoelectric vibrators. Also in the ultrasonic transducer of another embodiment using the even number of laminated piezoelectric vibrators, a signal voltage can be taken out between both lead wires, and the same can be used as a signal for imaging.
[0041]
As described above, in the present embodiment, an ultrasonic transducer that lowers the electrical impedance by using an even number of piezoelectric vibrators as a laminated structure, and has an electrode structure that does not require a wrap-around electrode for the laminated piezoelectric vibrators. Ultrasonic radiation efficiency can be increased by increasing the region that functions as a piezoelectric vibrator. Also, an electrode is provided on the surface of the acoustic matching layer, and this is connected to ground via a ground lead, so that the outermost electrical part as an ultrasonic transducer is a ground lead and an electrode connected thereto. This has the effect of protecting the living body from electrical insults required for medical equipment.
[0042]
Also, since the grounding lead and signal input / output lead are aligned and pulled out on the side of the ultrasonic transducer so that the interlinkage magnetic flux area is reduced, the ultrasonic signal is less affected by crosstalk between channels of the array and external noise. There is an effect that transmission and reception of data can be performed.
[0043]
【The invention's effect】
As described above, the ultrasonic transducer according to the present invention is an electrode that eliminates the need for a feed-in electrode in order to secure an effective area for ultrasonic radiation, even if the ultrasonic transducer has an even number of piezoelectric vibrators. The structure increases the area of ultrasonic radiation of the piezoelectric vibrator, and furthermore, the ground electrode is arranged on the outermost periphery of the electric structure of the ultrasonic transducer, so that electrical safety can be ensured. Further, since the ground electrode and the signal input / output electrode are arranged on the uppermost surface and the lowermost surface of the piezoelectric signal conductor having the acoustic matching layer, the ground lead wire and the signal input / output lead wire are integrated on one side of the ultrasonic transducer. It is possible to obtain an output signal which is less affected by crosstalk between channels and external noise.
[Brief description of the drawings]
FIG. 1 is a sectional view schematically showing an embodiment of an ultrasonic transducer according to the present invention.
FIG. 2 is a cross-sectional view schematically showing a four-layer stack as an example of another embodiment of the ultrasonic transducer of the present invention.
FIG. 3 is a sectional view schematically showing a conventional ultrasonic transducer using stacked piezoelectric vibrators.
[Explanation of symbols]
1 ... piezoelectric vibrator body,
1a, 1b, 1-1, 1-2, 21-1 to 21-4 ... piezoelectric vibrator,
2, 22 ... acoustic matching layer,
3a, 3b, 3c, 23b, 23c,... Electrodes
4a, 4b, 4c, 24a, 24c, ... electrodes
5 ... ground lead wire,
6 ... Signal input / output lead wire,
7, 27 ... backing material,
8 ... Acoustic lens,
9, 9a, 9b, 9c, 9d, 9e, 39 ... withstand pressure gap,
34a...

Claims (4)

A vibrator body in which an even number of piezoelectric vibrators having conductors on both surfaces are formed in a laminated structure to form an odd number of electrodes,
An acoustic matching layer disposed on one surface of the vibrator body and having electrodes on the surface;
A backing material fixed to a surface of the vibrator body opposite to the surface,
An odd number of electrodes of the vibrator body and an even number of electrodes composed of the electrodes of the acoustic matching layer are alternately connected to form two electrode sets,
An ultrasonic transducer having a ground lead connected to one of the two electrode sets and a signal input / output lead connected to the other. The two electrode sets are configured such that a ground lead is connected to a first electrode set including the electrodes of the acoustic matching layer, and a signal input / output lead is connected to a second electrode set of another electrode set. The ultrasonic transducer according to claim 1, wherein: The ground lead connected to the first set of electrodes and the signal input / output lead connected to the second set of electrodes are formed of the vibrator having the laminated structure and the backing material for holding the vibrator. 3. The ultrasonic transducer according to claim 2, wherein the ultrasonic transducers are arranged close to each other on the same side surface. A grounding lead connected to the first electrode set is connected to a grounding conductor shared with a grounding lead connected to a vibrator body having another laminated structure incorporated therein, and is connected to the second electrode set. The connected signal input / output leads are separated from the signal input / output leads connected to the other laminated vibrator body incorporated therein, and both are connected and supplied by flexible printed wiring. The ultrasonic transducer according to claim 3.

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