JP5065593B2 - Ultrasonic probe and ultrasonic imaging device - Google Patents

Description

  The present invention relates to an ultrasonic probe and an ultrasonic imaging apparatus that transmit and receive ultrasonic waves to and from an object to image the inside of the object.

  An ultrasonic probe is an apparatus that irradiates an ultrasonic wave toward the object and receives reflected waves from an interface with different acoustic impedances in the object for the purpose of imaging the inside of the object. . 2. Description of the Related Art As an ultrasonic imaging apparatus using an ultrasonic probe, an ultrasonic diagnostic imaging apparatus that inspects the inside of a living body such as a human body is known.

  The ultrasonic probe has a case body that is gripped by an operator, and an ultrasonic transducer for transmitting and receiving ultrasonic waves is housed in the case body.

  FIG. 6 is a configuration diagram of a conventional transducer.

  As shown in FIG. 6, the conventional ultrasonic transducer 100 includes a back material 101, a piezoelectric vibrator 102, an acoustic matching layer 103, and an acoustic lens 104 in order from the operator's hand side. The vibrator 102 and the acoustic matching layer 103 are divided into a plurality of piezoelectric elements 105 in the direction in which the ultrasonic waves are scanned.

  Each piezoelectric element 105 includes a GND electrode 105a on the surface on the acoustic matching layer 103 side, a signal electrode 105b on the surface on the back material 101 side, and delays the electrical signal to each signal electrode 105b, A sound wave scan is in progress.

  In other words, in order to execute an ultrasonic scan, it is necessary to separately apply an electrical signal having a slight delay time to the signal electrode 105b of each piezoelectric element 105. Therefore, an insulator capable of ensuring insulation between the signal electrodes 105b is used for the back material 101 that contacts the plurality of signal electrodes 105b.

  By the way, the ultrasonic wave generated from the piezoelectric vibrator 102 is converted into heat inside the acoustic lens 104 and the back material 101 in addition to being emitted to the living body side. Therefore, the ultrasound probe is required to ensure safety, and it is necessary to suppress the transmission voltage low so that the temperature of the living body contact portion of the ultrasound probe is equal to or lower than the regulation value.

However, if the transmission voltage is kept low, there is a problem in that the S / N ratio in the deep part of the living body is deteriorated and the image diagnostic ability is lowered. Therefore, in recent years, in order to solve this problem, a method of dissipating the heat from the piezoelectric vibrator to the case or the cable via the back material has been proposed (for example, see Patent Document 1).
JP 2004-56504 A

  However, the insulator which is the material of the back material has a thermal conductivity of about 0.2 [W / mK] to 1 [W / mK], and the heat dissipation efficiency is not so good. Therefore, there is a problem that the heat generated by the piezoelectric vibrator is not efficiently transferred through the back material, and the temperature of the living body contact portion of the ultrasonic probe rises.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic probe and an ultrasonic probe capable of suppressing an increase in surface temperature while ensuring insulation between piezoelectric elements. An object is to provide a sonic imaging apparatus.

  In order to solve the problems and achieve the object, the ultrasonic probe and the ultrasonic imaging apparatus of the present invention are configured as follows.

(1) A piezoelectric vibrator having electrodes on two surfaces parallel to each other, divided into an array in a direction substantially perpendicular to the two surfaces, and transmitting / receiving ultrasonic waves to / from an object, and the piezoelectric vibrator A back material that is disposed on one side of the two surfaces and attenuates ultrasonic waves from the piezoelectric vibrator, and a heat dissipation member that is connected to the back material and that releases heat of the back material. In the ultrasonic probe, the backing material has conductivity, an insulating member is interposed between the piezoelectric vibrator and the backing material, and a groove by dividing the array is formed partway through the insulating member. A damping member having a higher ultrasonic attenuation effect than the back material is disposed on the opposite side of the piezoelectric vibrator across the back material, and the back material is a resin mixture containing carbon filler or fiber. Formed and the acoustic impedance is 2Mray It is in the range of ~7Mrayl.

(2) In an ultrasonic imaging apparatus including an ultrasonic probe, the ultrasonic probe has electrodes on two parallel surfaces, and is divided into an array in a direction substantially perpendicular to the two surfaces. A piezoelectric vibrator that transmits / receives ultrasonic waves to / from an object, and a back material that is disposed on one side of the two faces with respect to the piezoelectric vibrator and attenuates ultrasonic waves from the piezoelectric vibrator And a heat radiating member connected to the back material and releasing the heat of the back material, the back material has conductivity, and an insulating member is interposed between the piezoelectric vibrator and the back material. In addition, a groove formed by dividing the array is formed partway through the insulating member, and on the opposite side of the piezoelectric vibrator across the back material, an attenuation member having a higher ultrasonic attenuation effect than the back material is disposed , The backing material is a resin mixture containing carbon filler or fiber. Is formed, the acoustic impedance is in the range of 2Mrayl～7Mrayl.

  According to the present invention, an increase in surface temperature can be suppressed while securing insulation between piezoelectric elements.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic view of an ultrasonic diagnostic apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus (ultrasonic imaging apparatus) according to the present embodiment includes an ultrasonic probe 1 and an ultrasonic diagnostic apparatus body 2, and uses a human body ( The internal state of the (object) is imaged.

  FIG. 2 is a configuration diagram of the ultrasound probe 1 according to the embodiment.

  As shown in FIG. 2, the ultrasound probe 1 is disposed in a case 10 that is gripped by an operator, a transducer 20 that is disposed in the case 10 and transmits / receives ultrasound to / from the human body, and the case 10. A flexible printed circuit (hereinafter referred to as “FPC”) 30 that transmits and receives electrical signals to and from the transducer 20, and a heat radiating plate (heat radiating member) 40 that is disposed in the case 10 and releases the heat of the transducer 20. The cable 50 is connected to the base end of the case 10 and connects the FPC 30 and the ultrasonic diagnostic apparatus main body 2.

  Next, each component will be described in detail. In the following description, the distal end side of the case 10 is the upper side, and the proximal end side of the case 10 is the lower side.

[Case 10]
The case 10 has an opening 11 at its upper end and an insertion hole 12 at its lower end. The transducer 20 (actually the acoustic lens 26) slightly protrudes from the opening 11, and a bush 60 for holding the cable 50 is fitted into the insertion hole 12.

[Transducer 20]
FIG. 3 is a perspective view of the transducer 20 according to the embodiment.

  As shown in FIG. 3, the transducer 20 includes a piezoelectric vibrator 21, an acoustic matching layer 22, a polyimide film (insulating member) 23, a first back material (back material) 24, and a second back material (attenuation member) 25. , And an acoustic lens 26.

  The piezoelectric vibrator 21 receives an electric signal and converts it into an ultrasonic wave, and receives an ultrasonic wave and converts it into an electric signal. The piezoelectric vibrator 21 includes a large number of piezoelectric elements 211.

  These piezoelectric elements 211 have a strip shape and are arranged at predetermined intervals in a direction substantially perpendicular to the axial center line of the case 10. As a material of the piezoelectric element 211, a two-component or three-component piezoelectric ceramic or the like is used. Hereinafter, the arrangement direction of the piezoelectric elements 211 is defined as an array direction, and a direction substantially perpendicular to the array direction and the vertical direction is defined as a lens direction.

  A gap between the piezoelectric vibrators 21, that is, a gap between the piezoelectric elements 211 and 211, is filled with a resin material (not shown) for ensuring the mechanical strength of the piezoelectric vibrator 21. An epoxy resin or the like is used as the material for the resin material.

  Each piezoelectric element 211 includes a GND electrode (electrode) 211a on the upper end surface and a signal electrode (electrode) 211b on the lower end surface. By applying an electric signal between these electrodes 211a and 211b, the axis of the piezoelectric element 211 is provided. Ultrasonic waves can be generated in the direction of the core wire, that is, in the vertical direction.

  A common electrode 212 for electrically sharing the GND electrode 211a of each piezoelectric element 211 is joined to one side surface of the piezoelectric vibrator 21 in the lens direction over the entire region in the array direction. The GND wiring 31 of the FPC 30 described above is connected to each GND electrode 211a via the common electrode 212, and the signal wiring 32 of the FPC 30 is connected to each signal electrode 211b.

  The acoustic matching layer 22 matches the acoustic impedance between the piezoelectric vibrator 21 and the human body. The acoustic matching layer 22 is disposed on the upper side of the piezoelectric vibrator 21 and includes a large number of acoustic matching elements 221.

  These acoustic matching elements 221 have a strip shape and are arranged at equal pitch intervals as the piezoelectric elements 211 in the array direction and the lens direction. The thickness of the acoustic matching element 221 in the vertical direction is set to ¼ of the wavelength λ of the ultrasonic wave transmitted from the piezoelectric vibrator 21.

  A gap between the acoustic matching layers 22, that is, a gap between the acoustic matching elements 221 and 221 is filled with a resin material (not shown) for ensuring the mechanical strength of the acoustic matching layer 22. An epoxy resin or the like is used as the material for the resin material.

  In this embodiment, the acoustic matching element 221 is formed of one material, but the acoustic impedance changes stepwise from the piezoelectric element 211 toward the human body using two different materials. It may be configured.

  The polyimide film 23 ensures insulation between the piezoelectric elements 211. The polyimide film 23 is interposed between the piezoelectric vibrator 21 and the first back material 24, and includes a groove portion 231 at a portion corresponding to the gap between the piezoelectric vibrator 21 and the acoustic matching layer 22.

In addition, the thermal conductivity of the polyimide film 23 is about 0.2 [W / mK], and the acoustic impedance of the polyimide film 23 is about 3 [Mra yl ] to 4 [Mra yl ].

  The thickness of the polyimide film 23 is set to 1/10 or less of the wavelength λ of the ultrasonic wave, that is, λ / 10 or less. For example, when the sound speed is 2200 [m / s] and the ultrasonic frequency is 5 [MHz], the thickness of the polyimide film 23 is 44 [μm] or less.

  The first backing member 24 attenuates the ultrasonic wave propagating to the lower side of the ultrasonic wave generated by the piezoelectric vibrator 21, that is, the operator's hand side, and converts it into heat. The first back material 24 is disposed below the polyimide film 23.

As the material of the first backing material 24, a resin mixture containing isotropic graphite, metal, carbon filler or fiber having high thermal conductivity and conductivity is used. Further, the acoustic impedance of the first back member 24 is preferably in the range of 2 [Mra yl ] to 7 [Mra yl ] with good ultrasonic convergence.

Therefore, in the present embodiment, isotropic graphite having a thermal conductivity of 90 [W / mK] and an acoustic impedance of 5 [Mra yl ] is used as a material for the first back material 24. As a result, the heat of the transducer 20 is efficiently transferred through the first back material 24.

  The second backing material 25 attenuates ultrasonic waves that have not been attenuated by the first backing material 24 out of the ultrasonic waves generated by the piezoelectric vibrator 21 and converts them into heat. The second back material 25 is disposed below the first back material 24.

As a material for the second backing material 25, a resin mixture containing an oxide filler is used. The acoustic impedance of the second backing material 25 is substantially the same as that of isotropic graphite in order to prevent reflection of ultrasonic waves at the joint surface between the first backing material 24 and the second backing material 25. It is set to equal 5 [Mra yl ].

  The acoustic lens 26 uses an acoustic refraction to converge the ultrasonic beam and improve the ultrasonic resolution. The acoustic lens 26 is disposed on the upper side of the acoustic matching layer 22 so as to cover all the acoustic matching elements 221.

  As a material of the acoustic lens 26, silicone rubber or the like is used. The acoustic impedance of the acoustic lens 26 is set to a value close to the acoustic impedance of the human body in order to prevent reflection of ultrasonic waves at the contact surface between the human body and the acoustic lens 26.

[FPC30]
The FPC 30 is disposed on one side of the transducer 20 in the lens direction, and has a planar two-layer structure mainly including a GND wiring 31 and a signal wiring 32. The GND wiring 31 and the signal wiring 32 are separated in the middle of the FPC 30, and are connected to the common electrode 212 and the signal electrode 211b at the respective leading ends.

[Heatsink 40]
The heat radiating plate 40 is joined to both side surfaces of the first back member 24 in the lens direction by screws (not shown) or the like. The heat radiating plate 40 extends from a middle part in the vertical direction of the first back member 24 to the lower side of the case 10, and protrudes from the end surface of the cable 50 when closest to the lower end of the case 10. It is connected to a shield wire (described later) 53 (see FIG. 2). As the material of the heat sink 40, copper having a thermal conductivity of about 200 [W / mK] is used.

[Cable 50]
FIG. 4 is a cross-sectional view of the cable 50 according to the embodiment.

  As shown in FIG. 4, the cable 50 is held at the lower end of the case 10 by the bush 60, and mainly includes a plurality of signal lines 51, a resin material 52 that covers the periphery of the signal lines 51, and a resin material 52. Is formed of a large number of shield wires 53 arranged in an annular shape on the outer peripheral portion of the wire and an outer skin 54 covering the outside of the shield wires 53.

  The shield line 53 is for protecting the signal line 51 from external noise. The shield wire 53 protrudes from the end face of the cable 50 on the case 10 side and is connected to the lower side of the heat sink 40. As a material for the shield wire 53, a highly conductive metal such as copper or aluminum is used.

  Next, a manufacturing process of the ultrasonic probe 1 having the above configuration will be briefly described.

  First, a piezoelectric vibration block and an acoustic matching block are prepared. The piezoelectric vibration block is obtained by forming an electrode on a piezoelectric material formed in a block shape by plating or sputtering, and then performing polarization treatment on the piezoelectric material.

  When the piezoelectric vibration block and the acoustic matching block are prepared, the acoustic matching block is joined to one electrode of the piezoelectric vibrator block, and the piezoelectric vibration block and the acoustic matching block are processed to a desired thickness and size.

  Next, the signal wiring 32 of the FPC 30 is connected to the electrode to which the acoustic matching block is bonded among the electrodes of the piezoelectric vibrator block. In this state, the signal wiring of the FPC 30 is a single thin film. And the polyimide film 23, the 1st back material 24, and the 2nd back material 25 are joined in order on the opposite side of an acoustic matching block on both sides of a piezoelectric vibrator block, and the middle part of the polyimide film 23 from the acoustic matching block side Dicing is performed until

  Thus, the piezoelectric vibrator block is divided into a plurality of piezoelectric elements 211 to become the piezoelectric vibrator 21, and the acoustic matching block is divided into a plurality of acoustic matching elements 221 to become the acoustic matching layer 22. In addition, a plurality of grooves 231 are formed in the polyimide film 23. Further, the signal wiring 32 of the FPC 30 is divided for each piezoelectric element 211 of the piezoelectric vibrator 21.

  Next, the common electrode 212 is joined to one side surface of the piezoelectric vibrator 21 in the lens direction, and the GND electrodes 211 a and the GND wiring 31 of the FPC 30 are connected via the common electrode 212.

  After filling the gap between the piezoelectric vibrator 21 and the acoustic matching layer 22 with a resin material, the acoustic lens 6 is bonded to the opposite side of the piezoelectric vibrator 21 with the acoustic matching layer 22 interposed therebetween. Thus, the transducer 20 having the above configuration is completed.

  Next, the transducer 20 is housed in the case 10, and the heat radiating plates 40 are joined to both side surfaces of the first back material 24 in the array direction. And while connecting FPC30 and the cable 50, the heat sink 40 and the shield wire 53 of the cable 50 are connected. Thus, the ultrasonic probe 1 according to the present embodiment is completed.

  Next, the operation of the ultrasonic probe having the above configuration will be described.

  In the present embodiment, the first back material 24 is disposed below the piezoelectric vibrator 21 and isotropic graphite having high thermal conductivity is used as the material. Therefore, the heat of the transducer 20 flows into the heat radiating plate 40 without stagnation in the first back material 24, and is quickly radiated from the shield wire 53 of the cable 50, so that the temperature rise of the acoustic lens 26 that contacts the human body is suppressed. can do.

  As a result, since it is possible to set a high transmission voltage for use in ultrasonic diagnosis, a high-quality ultrasonic image with a good S / N ratio is acquired even when imaging the deep part of the living body. be able to.

  Further, a polyimide film 23 is interposed between the piezoelectric vibrator 21 and the first back material 24. Therefore, insulation between the piezoelectric elements 211 is ensured, and separate electric signals can be applied to each piezoelectric element 211.

  Moreover, the thickness of the polyimide film 23 is set to 1/10 or less of the ultrasonic wavelength λ. Therefore, since the acoustic influence on the transmitted and received ultrasonic waves can be reduced to a negligible level, a polyimide film 23 is interposed between the piezoelectric vibrator 21 and the first back material 24 as in this embodiment. However, the quality of the ultrasonic image is not deteriorated.

  In the present embodiment, the second back material 25 having a higher damping effect than the first back material 24 is disposed below the first back material 24. Therefore, even if the material of the first back material 24 is a material having a small attenuation effect, the ultrasonic waves from the piezoelectric vibrator 21 can be sufficiently attenuated by the second back material 25. Conversely, as in the present embodiment, by arranging the second back material 25 below the first back material 24, the range of material selection for the first back material 24 can be expanded. It becomes.

In the present embodiment, the acoustic impedance of the second back member 25 is set to 5 [Mra yl ] equal to the acoustic impedance of the first back member 24. Therefore, it is possible to prevent reflection of ultrasonic waves at the joint surface between the first back material 24 and the second back material 25.

  In the present embodiment, the thickness of the polyimide film 23 is λ / 10 or less. However, if the thickness of the acoustic matching layer 22 is less than the thickness, that is, λ / 4 or less, the heat of the transducer 20 is on the acoustic lens 26 side. Therefore, it is possible to achieve the object of the present invention to prevent the temperature of the portion of the ultrasonic probe 1 in contact with the human body from being increased.

  In the present embodiment, in order to attenuate the ultrasonic wave, two backing materials, that is, the first backing material 24 and the second backing material 25 are arranged below the piezoelectric vibrator 21. The invention is not limited to this.

  That is, if a resin mixture containing a carbon fiber having a thermal conductivity of 500 [W / mK] is used as the material of the first back member 24, the attenuation coefficient increases to about 5 [dB / MHz · mm]. The ultrasonic wave can be sufficiently attenuated only by the first backing material 24.

The acoustic impedance of the first back member 24 including the carbon fiber is about 4 [MRa yl ], and the thermal conductivity is about 10 [W / mK].

  Next, a second embodiment of the present invention will be described with reference to FIG. Here, the description of the same configuration and operation as those of the first embodiment is omitted.

  FIG. 5 is a configuration diagram of an ultrasonic probe 1A according to the second embodiment of the present invention.

  As shown in FIG. 5, the present embodiment is an example in which the technique of the present invention is applied to a two-dimensional array type ultrasonic probe 1A. The two-dimensional array type ultrasonic probe 1 </ b> A includes a drive circuit 70 for driving the transducer 20 on the proximal end side in the case 10.

  For this reason, when the two-dimensional array type ultrasonic probe 1A is used, heat is generated from the drive circuit 70, and the ultrasonic probe 1A may be heated. However, as in the present embodiment, the first back material 24 is disposed below the piezoelectric vibrator 21 via the polyimide film 23, and heat is discharged from the shield wire 53 of the cable 50 via the heat radiating plate 40. Then, heating of the transducer 20 caused by the drive circuit 70 can be suppressed while ensuring insulation between the piezoelectric elements 211.

  As a result, since the transmission voltage that can be used at the time of ultrasonic diagnosis can be set high, a high-quality ultrasonic image with a good S / N ratio can be acquired even when imaging the deep part of the living body. .

  The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the spirit of the invention in the stage of implementation. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  That is, the application target of the present invention is not limited to a medical ultrasonic diagnostic apparatus, and may be applied to an image of an internal state of a structure (object) such as an ultrasonic flaw detector. .

1 is a schematic diagram of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. The lineblock diagram of the ultrasonic probe concerning the form. The perspective view of the transducer which concerns on the same embodiment. Sectional drawing of the cable which concerns on the same embodiment. The block diagram of the ultrasonic probe which concerns on the 2nd Embodiment of this invention. The block diagram of the conventional ultrasonic transducer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ultrasonic probe, 1A ... Ultrasonic probe, 21 ... Piezoelectric vibrator, 22 ... Acoustic matching layer, 23 ... Polyimide film (insulating member), 24 ... First back material (back material), 25 2nd back material (attenuation member), 40 ... Radiation plate (heat dissipation member), 211a ... GND electrode (electrode), 211b ... Signal electrode (electrode).

Claims (6)

Piezoelectric vibrators having electrodes on two parallel surfaces, arrayed in a direction substantially perpendicular to the two surfaces, and transmitting and receiving ultrasonic waves to and from the object;
A back material that is disposed on one side of the two surfaces with respect to the piezoelectric vibrator and attenuates ultrasonic waves from the piezoelectric vibrator;
In the ultrasonic probe provided with a heat radiating member connected to the back material and releasing heat of the back material,
The backing material has conductivity, an insulating member is interposed between the piezoelectric vibrator and the backing material, and a groove by array division is formed partway through the insulating member,
On the opposite side of the piezoelectric vibrator across the back material, an attenuation member having a higher ultrasonic attenuation effect than the back material is disposed ,
The backing material is formed of a resin mixture containing carbon filler or fiber, and has an acoustic impedance in the range of 2 Mrayl to 7 Mrayl.
An ultrasonic probe characterized by that.   An acoustic matching layer for matching the acoustic impedance between the piezoelectric vibrator and the object is disposed on the opposite side of the back material with the piezoelectric vibrator interposed therebetween, and the insulating member extends in the transmission / reception direction. The ultrasonic probe according to claim 1, wherein a thickness of the acoustic matching layer is smaller than a thickness of the acoustic matching layer in the transmission / reception direction.   The ultrasonic probe according to claim 1, wherein a thickness of the insulating member in the transmission / reception direction is 1/10 or less of a wavelength of the ultrasonic wave.   The ultrasonic probe according to claim 1, wherein the heat radiating member is provided on the back material and at a position separated from the piezoelectric vibrator and the insulating member.   The ultrasonic probe according to claim 1, wherein an acoustic impedance of the attenuation member is substantially equal to an acoustic impedance of the back member. In an ultrasound imaging apparatus equipped with an ultrasound probe,
The ultrasonic probe is
Piezoelectric vibrators having electrodes on two parallel surfaces, arrayed in a direction substantially perpendicular to the two surfaces, and transmitting and receiving ultrasonic waves to and from the object;
A back material that is disposed on one side of the two surfaces with respect to the piezoelectric vibrator and attenuates ultrasonic waves from the piezoelectric vibrator;
A heat radiating member connected to the back material and releasing the heat of the back material;
The backing material has conductivity, an insulating member is interposed between the piezoelectric vibrator and the backing material, and a groove by array division is formed partway through the insulating member,
On the opposite side of the piezoelectric vibrator across the back material, an attenuation member having a higher ultrasonic attenuation effect than the back material is disposed ,
The backing material is formed of a resin mixture containing carbon filler or fiber, and has an acoustic impedance in the range of 2 Mrayl to 7 Mrayl.
An ultrasonic imaging apparatus characterized by that.

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