JP2020116099A - Ultrasonic probe and ultrasonic diagnostic apparatus - Google Patents

Abstract

To easily eliminate characteristic deterioration of a piezoelectric element due to a pyroelectric effect.SOLUTION: An ultrasonic probe 2 comprises: a piezoelectric element 23 for transmitting and receiving ultrasonic waves between an analyte and itself; an I/O signal line 27 which is connected electrically to an I/O electrode 22 provided on the piezoelectric element 23 and through which a drive signal input to the piezoelectric element 23 and a reception signal output from the piezoelectric element 23 flow; a GND signal line 28 which is provided spaced from the I/O signal line 27 and connected electrically with a GND electrode 24 provided on the piezoelectric element 23; and a thermally deformed part 29 which is deformed thermally and brings the I/O signal line 27 and the GND signal line 28 into contact with each other at a temperature equal to or higher than a predetermined temperature.SELECTED DRAWING: Figure 4

Description

The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus.

In ultrasonic diagnosis, the state of the heart and fetus can be obtained as an ultrasonic image with a simple operation of applying an ultrasonic probe from the body surface or inside the body cavity, and since it is highly safe, repeated examinations can be performed. .. An ultrasonic diagnostic apparatus used for performing such ultrasonic diagnosis is known. For ultrasonic image data, ultrasonic waves are transmitted from the ultrasonic probe having a piezoelectric element to the subject, the ultrasonic waves are reflected by the ultrasonic probe, and various processing is performed on the received signals. Can be obtained at.

In an ultrasonic probe, the characteristics of the piezoelectric element may deteriorate due to the generation of an electric field generated by the pyroelectric effect of the piezoelectric element. The pyroelectric effect refers to a phenomenon in which the polarization (surface charge) of a dielectric changes due to temperature change. Generally, a material having a larger piezoelectric characteristic has a larger pyroelectric coefficient. Therefore, when a material having a high piezoelectric characteristic is used for a piezoelectric element, this charge amount inevitably increases, and as a result, a large electric field is applied to the piezoelectric element. .. A reverse electric field may be applied to the polarization direction of the piezoelectric element due to the influence of this electric field. If the electric field is large, that is, if the pyroelectric coefficient is large, a depolarizing action may be exerted on the piezoelectric element. is there. It is clear that the depolarization action leads to deterioration of device characteristics.

For this reason, there is known an ultrasonic probe in which a resistance (conductive paste) is applied between the metal electrodes of a piezoelectric element and electric charges generated by heat are constantly discharged to prevent voltage application to the element due to the pyroelectric effect. (See Patent Document 1).

Further, the signal line connected to the piezoelectric element (piezoelectric body) when not driven and the ground line are short-circuited by the control signal of the ultrasonic driving voltage, and the piezoelectric element of the piezoelectric element in a high temperature environment when not in use or a rapid temperature change environment is used. An ultrasonic probe that maintains reliability is known (see Patent Document 2).

JP-A-11-330578 Japanese Patent No. 6271127

However, in the ultrasonic probe of Patent Document 1, a resistor is always connected between the metal electrode on the signal line side and the metal electrode on the ground line side of the piezoelectric element. Therefore, the characteristics of the piezoelectric element deteriorate due to the resistance.

Further, in the ultrasonic probe of Patent Document 2, the switch is switched depending on the presence or absence of the control signal of the ultrasonic drive voltage, and the signal line and the ground line are short-circuited/opened. Specifically, when there is an ultrasonic drive voltage control signal, the signal line and the ground line are opened, and when there is no ultrasonic drive voltage control signal, the signal line and the ground line are short-circuited. Therefore, electrical control by the control signal of the ultrasonic drive voltage is required, and the cost increases.

An object of the present invention is to easily eliminate characteristic deterioration of a piezoelectric element due to a pyroelectric effect.

In order to solve the above problems, the ultrasonic probe of the invention according to claim 1 is
A piezoelectric element that transmits and receives ultrasonic waves to and from the subject,
An electric signal line electrically connected to the first electrode provided on the piezoelectric element, through which a drive signal input to the piezoelectric element and a reception signal output from the piezoelectric element flow,
A ground signal line provided with a gap from the electric signal line and electrically connected to a second electrode provided on the piezoelectric element;
And a thermal deformation unit that is deformed by temperature and contacts the electric signal line and the ground signal line at a predetermined temperature or higher.

The invention according to claim 2 is the ultrasonic probe according to claim 1,
The thermal deformation part is made of a conductor and functions as a part of at least one of the electric signal line and the ground signal line.

The invention according to claim 3 is the ultrasonic probe according to claim 1 or 2, wherein:
At least one of the electric signal line and the ground signal line includes an insulator part formed on the surface.

The invention according to claim 4 is the ultrasonic probe according to claim 3,
The electric signal line and the ground signal line are formed on the surface of the insulator part,
A cavity that insulates the electric signal line and the ground signal line, and is brought into contact with the electric signal line and the ground signal line by deformation of the thermal deformation unit.

The invention according to claim 5 is the ultrasonic probe according to claim 3,
The insulator part is arranged outside the electric signal line and the ground signal line, and the electric signal line or the ground signal line is formed on the surface of the piezoelectric element side.

The invention according to claim 6 is the ultrasonic probe according to any one of claims 1 to 5, wherein:
The thermal deformation part is made of bimetal.

The invention according to claim 7 is the ultrasonic probe according to any one of claims 1 to 6, wherein:
The thermal deformation part has a heat dissipation function.

The invention according to claim 8 is the ultrasonic probe according to any one of claims 1 to 7,
The electric signal line, the ground signal line, and the thermal deformation section are arranged in parallel.

The ultrasonic diagnostic apparatus of the invention according to claim 9 is
An ultrasonic probe according to any one of claims 1 to 8,
A transmitter that generates the drive signal and outputs the drive signal to the ultrasonic probe;
An image generation unit that generates ultrasonic image data based on the received signal input from the ultrasonic probe.

According to the present invention, the characteristic deterioration of the piezoelectric element due to the pyroelectric effect can be easily eliminated.

It is an external view of the ultrasonic diagnosing device of embodiment of this invention. It is a block diagram showing functional composition of an ultrasonic diagnostic equipment. It is a sectional view of an ultrasonic probe of an embodiment. (A) is sectional drawing which shows some ultrasonic probes before deformation|transformation of embodiment. (B) is a cross-sectional view showing a part of the ultrasonic probe after the deformation of the embodiment. (A) is sectional drawing which shows some ultrasonic probes before a deformation|transformation of 1st Example. FIG. 6B is a cross-sectional view showing a part of the ultrasonic probe after the modification of the first embodiment. (A) is sectional drawing which shows a part of ultrasonic probe before a deformation|transformation of a 2nd Example. (B) is a cross-sectional view showing a part of the ultrasonic probe after deformation of the second embodiment. (A) is sectional drawing which shows a part of ultrasonic probe before a deformation|transformation of a 3rd Example. (B) is a sectional view showing a part of the ultrasonic probe after the modification of the third embodiment. (A) is sectional drawing which shows some ultrasonic probes before a deformation|transformation of a 4th Example. FIG. 9B is a cross-sectional view showing a part of the ultrasonic probe after deformation of the fourth embodiment.

Embodiments and first to fourth examples according to the present invention will be sequentially described in detail with reference to the accompanying drawings. The present invention is not limited to the illustrated example.

(Embodiment)
An embodiment according to the present invention will be described with reference to FIGS. First, the overall configuration of the ultrasonic diagnostic apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is an external view of an ultrasonic diagnostic apparatus 100 according to this embodiment.

As shown in FIG. 1, the ultrasonic diagnostic apparatus 100 includes an ultrasonic diagnostic apparatus main body 1 and an ultrasonic probe 2. The ultrasonic probe 2 transmits an ultrasonic wave (transmission ultrasonic wave) to an inside of a subject such as a living body (not shown), and also a reflected wave of the ultrasonic wave reflected within the subject (reflected ultrasonic wave: echo). To receive. The ultrasonic diagnostic apparatus main body 1 is connected to the ultrasonic probe 2 via a cable 3 and transmits a drive signal of an electric signal to the ultrasonic probe 2 so that the ultrasonic probe 2 can be applied to a subject. Based on the received signal which is an electric signal generated by the ultrasonic probe 2 in response to the reflected ultrasonic wave from the inside of the subject received by the ultrasonic probe 2, The internal state of the subject is imaged as ultrasonic image data.

The ultrasonic probe 2 includes a vibrator 2a (see FIG. 2) including a piezoelectric element, and the vibrators 2a are arranged in a one-dimensional array in the azimuth direction (scanning direction), for example. .. In this embodiment, for example, the ultrasonic probe 2 including 192 transducers 2a is used. The vibrators 2a may be arranged in a two-dimensional array. Further, the number of vibrators 2a can be set arbitrarily. Further, in the present embodiment, a linear electronic scan probe is used as the ultrasonic probe 2 to perform ultrasonic scanning by the convex scanning method, but either the linear scanning method or the sector scanning method is used. It can also be adopted. Communication between the ultrasonic diagnostic apparatus body 1 and the ultrasonic probe 2 may be performed by wireless communication such as UWB (Ultra Wide Band) instead of wire communication via the cable 3.

Next, the functional configuration of the ultrasonic diagnostic apparatus 100 will be described with reference to FIG. FIG. 2 is a block diagram showing the functional configuration of the ultrasonic diagnostic apparatus 100.

As shown in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes, for example, an operation input unit 11, a transmission unit 12, a reception unit 13, an image generation unit 14, an image processing unit 15, and a DSC (Digital Scan Converter). ) 16, a display unit 17, and a control unit 18.

The operation input unit 11 receives operation inputs from operators such as doctors and technicians. The operation input unit 11 is, for example, a command for instructing the start of diagnosis, data such as personal information of the subject, various switches for inputting various image parameters for displaying ultrasonic image data, and the like. , A button, a trackball, a mouse, a keyboard, etc., and outputs an operation signal to the control unit 18. The ultrasonic diagnostic apparatus body 1 may be configured to include a touch panel that is provided on the display panel of the display unit 17 and that receives a touch input from the operator.

The transmission unit 12 is a circuit that supplies a drive signal, which is an electric signal, to the ultrasonic probe 2 via the cable 3 and causes the ultrasonic probe 2 to generate a transmitted ultrasonic wave under the control of the control unit 18. .. The transmission unit 12 also includes, for example, a clock generation circuit, a delay circuit, and a pulse generation circuit. The clock generation circuit is a circuit that generates a clock signal that determines the transmission timing and the transmission frequency of the drive signal. The delay circuit sets a delay time for each individual path corresponding to each transducer 2a, delays the transmission of the drive signal by the set delay time, and focuses the transmission beam constituted by the transmitted ultrasonic waves. Circuit. The pulse generation circuit is a circuit for generating a pulse signal as a drive signal at a predetermined cycle. The transmission unit 12 configured as described above drives, for example, a continuous part (for example, 64) of the plurality of (for example, 192) transducers 2a arranged in the ultrasonic probe 2. Then, a transmission ultrasonic wave is generated. Then, the transmission unit 12 performs scanning by scanning the transducer 2a, which is driven each time a transmission ultrasonic wave is generated, in the azimuth direction (scanning direction).

The reception unit 13 is a circuit that receives a reception signal, which is an electric signal, from the ultrasonic probe 2 via the cable 3 under the control of the control unit 18. The reception unit 13 includes, for example, an amplifier, an A/D conversion circuit, and a phasing addition circuit. The amplifier is a circuit for amplifying the received signal with a preset amplification factor for each individual path corresponding to each transducer 2a. The A/D conversion circuit is a circuit for performing analog-digital conversion (A/D conversion) on the amplified reception signal. The phasing addition circuit gives a delay time to the A/D-converted reception signal for each individual path corresponding to each transducer 2a to adjust the time phase, and adds these (phasing addition) to generate a sound. This is a circuit for generating line data.

Under the control of the control unit 18, the image generation unit 14 performs envelope detection processing, logarithmic compression, or the like on the sound ray data from the reception unit 13, adjusts the dynamic range and gain, and performs luminance conversion. It is possible to generate B (Brightness) mode image data including pixels having a luminance value as received energy. That is, the B-mode image data represents the strength of the received signal by the brightness. The image generation unit 14, in addition to the B mode image data as the ultrasonic image data of which the image mode is the B mode, the A (Amplitude) mode, the M (Motion) mode, the image mode by the Doppler method (color Doppler mode, etc.), etc. The ultrasonic image data of another image mode may be generated.

Under the control of the control unit 18, the image processing unit 15 performs image processing on the B-mode image data output from the image generation unit 14 according to various image parameters being set. The image processing unit 15 also includes an image memory unit 15a configured by a semiconductor memory such as a DRAM (Dynamic Random Access Memory). Under the control of the control unit 18, the image processing unit 15 stores the image-processed B-mode image data in the image memory unit 15a in frame units. Image data in frame units may be referred to as ultrasonic image data or frame image data. The image processing unit 15 sequentially outputs the image data generated as described above to the DSC 16 under the control of the control unit 18.

Under the control of the control unit 18, the DSC 16 converts the image data received from the image processing unit 15 into an image signal for display and outputs the image signal to the display unit 17.

As the display unit 17, a display device such as an LCD (Liquid Crystal Display), a CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic EL display, and a plasma display can be applied. The display unit 17 displays a still image or a moving image of ultrasonic image data on the display screen according to the image signal output from the DSC 16 under the control of the control unit 18. Further, the display unit 17 can adjust the dynamic range under the control of the control unit 18.

The control unit 18 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and reads out various processing programs such as a system program stored in the ROM and expands them in the RAM. The operation of each unit of the ultrasonic diagnostic apparatus 100 is controlled according to the expanded program. The ROM is configured by a non-volatile memory such as a semiconductor, and stores a system program corresponding to the ultrasonic diagnostic apparatus 100, various processing programs executable on the system program, various data such as a gamma table, and the like. These programs are stored in the form of computer-readable program code, and the CPU sequentially executes operations according to the program code. The RAM forms a work area for temporarily storing various programs executed by the CPU and data related to these programs.

Regarding each unit included in the ultrasonic diagnostic apparatus 100, some or all of the functions of each functional block can be realized as a hardware circuit such as an integrated circuit. The integrated circuit is, for example, an LSI (Large Scale Integration), and the LSI may be called an IC (Integrated Circuit), a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor, and connections and settings of FPGA (Field Programmable Gate Array) and circuit cells inside the LSI can be reconfigured. A reconfigurable processor may be used. Further, some or all of the functions of each functional block may be executed by software. In this case, this software is stored in a storage medium such as one or more ROMs, an optical disk, a hard disk, or the like, and this software is executed by the arithmetic processing unit.

Next, an internal configuration of the ultrasonic probe 2 will be described with reference to FIGS. 3 and 4. FIG. 3 is a sectional view of the ultrasonic probe 2. FIG. 4A is a sectional view showing a part of the ultrasonic probe 2 before deformation. FIG. 4B is a sectional view showing a part of the ultrasonic probe 2 after deformation.

As shown in FIG. 3, the ultrasonic probe 2 includes a back surface layer 21, an I/O (Input/Output) electrode 22 as a first electrode, a piezoelectric element 23, and a GND as a second electrode. A (GrouND) electrode 24, an acoustic matching layer 25, an acoustic lens 26, an I/O signal line 27 as an electric signal line, a GND signal line 28 as a ground signal line, and a thermal deformation section 29. .. The back surface layer 21, the I/O electrode 22, the piezoelectric element 23, the GND electrode 24, the acoustic matching layer 25, and the acoustic lens 26 are sequentially stacked from the lower side to the upper side in the front view of the drawing.

The back surface layer 21 is made of, for example, a back surface loading material (backing material). The back load material is an ultrasonic absorber that is made of a material whose acoustic impedance is lower than that of the piezoelectric element 23 and that can absorb unnecessary ultrasonic waves. That is, the back load material absorbs ultrasonic waves generated from the opposite side of the piezoelectric element.

As the back load material, natural rubber, ferrite rubber, epoxy resin, rubber-based composite material, epoxy resin composite material, vinyl chloride, polyvinyl resin obtained by press-molding powder of tungsten oxide, titanium oxide, ferrite, etc. into these materials is used. Butyral (PVB), ABS resin, polyurethane (PUR), polyvinyl alcohol (PVAL), polyethylene (PE), polypropylene (PP), polyacetal (POM), polyethylene terephthalate (PETP), fluororesin (PTFE) polyethylene glycol, polyethylene terephthalate -A thermoplastic resin such as a polyethylene glycol copolymer can be applied.

A preferable back load material is made of a rubber-based composite material and/or an epoxy resin composite material, and the shape thereof is appropriately selected according to the shape of the back surface layer 21, the piezoelectric element 23, and the probe head including them. can do.

The piezoelectric element 23 has the I/O electrode 22 formed on the lower surface and the GND electrode 24 formed on the upper surface, and is laminated on the back surface layer 21. The piezoelectric element 23 is an element (piezoelectric element) having a piezoelectric material, capable of converting an electric signal into a mechanical vibration and a mechanical vibration into an electric signal, capable of transmitting and receiving an ultrasonic wave, and having a pyroelectric effect. is there.

The piezoelectric material is a material containing a piezoelectric body capable of converting an electric signal into a mechanical vibration and a mechanical vibration into an electric signal. Examples of the piezoelectric body include lead zirconate titanate (PZT) ceramics, lead titanate, piezoelectric metabolites such as lead metaniobate, lithium niobate, lead zinc niobate and lead titanate, lead magnesium niobate and lead titanate, and the like. Single crystal of solid solution type single crystal, quartz, Rochelle salt, polyvinylidene fluoride (PVDF), or polyvinylidene fluoride-3 fluoride ethylene which is a copolymer of VDF and ethylene trifluoride (TrFE) PVDF copolymer such as (P(VDF-TrFE)), polyvinylidene cyanide (PVDCN) which is a polymer of vinylidene cyanide (VDCN), or vinylidene cyanide copolymer or nylon 9, nylon 11 or the like. Odd-numbered nylon, aromatic nylon, alicyclic nylon, polylactic acid, polyhydroxycarboxylic acid such as polyhydroxybutyrate, cellulose derivative, organic polymer piezoelectric material such as polyurea, and the like can be used.

The thickness of the piezoelectric material is, for example, in the range of 100 to 500 [μm]. The piezoelectric element 23 is used as the vibrator 2a in a state where the I/O electrode 22 and the GND electrode 24 are attached to both surfaces thereof.

Materials used for the I/O electrode 22 and the GND electrode 24 include gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), nickel (Ni). , Tin (Sn), and the like.

As a method of attaching the I/O electrode 22 and the GND electrode 24 to the piezoelectric element 23, for example, a base metal such as titanium (Ti) or chromium (Cr) is sputtered to a thickness of 0.02 to 1.0 [μm]. To a thickness of 1 to 10 [μm] by a sputtering method or other suitable method after forming a metal material mainly composed of the above metal elements and alloys thereof, and optionally a partially insulating material. There is a method of forming.

The I/O electrode 22 and the GND electrode 24 may be formed by a screen printing method, a dipping method, or a thermal spraying method, instead of the sputtering method, by using a conductive paste in which a fine metal powder and a low melting point glass are mixed. The I/O electrode 22 and the GND electrode 24 are provided on the surface of the piezoelectric element 23 according to the shape of the ultrasonic probe 2.

In the piezoelectric element 23, the I/O electrode 22 is electrically connected to the I/O signal line 27, the I/O signal line 27 is electrically connected to the I/O signal line of the cable 3, The GND electrode 24 is electrically connected to the GND signal line 28, and the GND signal line 28 is electrically connected to the GND signal line of the cable 3. Therefore, the drive signal output from the ultrasonic diagnostic apparatus body 1 is input to the piezoelectric element 23, and the reception signal generated by the piezoelectric element 23 is output to the ultrasonic diagnostic apparatus body 1.

The acoustic matching layer 25 matches the acoustic impedance between the piezoelectric element 23 and the acoustic lens 26, and suppresses reflection at the boundary surface between the piezoelectric element 23, the acoustic matching layer 25, and the acoustic lens 26. The acoustic matching layer 25 is attached to the subject side with respect to the piezoelectric element 23.

The acoustic matching layer 25 is composed of a single layer or a plurality of layers stacked. The acoustic impedance of the acoustic matching layer 25 in which the thicknesses of the plurality of layers are matched is gradually reduced from the lowermost layer to the uppermost layer, and the acoustic impedance of the lowermost layer is set to be less than the acoustic impedance of the piezoelectric element 23. Further, in order to match with the acoustic impedance of the acoustic lens 26 described later, it is preferable to make the difference between the acoustic impedance of the uppermost layer and the acoustic impedance of the acoustic lens 26 smaller, and more preferably, the uppermost layer and the acoustic lens 26. The acoustic matching layer 25 is provided so that the acoustic impedance of the uppermost layer at the interface becomes substantially equal to the acoustic impedance of the acoustic lens 26.

As a material used for the acoustic matching layer 25, specifically, aluminum, aluminum alloy (for example, AL-Mg alloy), magnesium alloy, macor glass, glass, fused quartz, copper graphite, PE (polyethylene) or PP (polypropylene). , PC (polycarbonate), ABC resin, ABS resin, AAS resin, AES resin, nylon (PA6, PA6-6), PPO (polyphenylene oxide), PPS (polyphenylene sulfide: glass fiber is acceptable), PPE (polyphenylene ether) , PEEK (polyether ether ketone), PAI (polyamide imide), PETP (polyethylene terephthalate), epoxy resin, urethane resin and the like. Preferably, a thermosetting resin such as an epoxy resin is molded by adding tungsten, zinc white, titanium oxide, silica or alumina, red iron oxide, ferrite, tungsten oxide, yttrium oxide, barium sulfate, molybdenum, etc. as a filler. Applicable. Here, by making the type, amount, distribution, etc. of the filler different in each layer, it is possible to make the acoustic impedance of each layer different even for the same type of resin.

The acoustic lens 26 is arranged in order to focus the ultrasonic beam using refraction and improve the resolution. That is, the acoustic lens 26 is provided on the side of the ultrasonic probe 2 that is in contact with the subject, and causes the ultrasonic waves generated by the piezoelectric element 23 to efficiently enter the subject. The acoustic lens 26 has a convex or concave lens shape in a portion in contact with the subject according to the internal sound velocity, and ultrasonic waves incident on the subject are measured in a thickness direction (elevation) orthogonal to the imaging cross section. Direction).

The acoustic impedance of the acoustic lens 26 is appropriately set so that the attenuation or reflection of ultrasonic waves between the acoustic lens 26 and the subject becomes smaller than the acoustic impedance of the subject. Here, since the subject is a human body or the like, generally, the acoustic impedance of the acoustic lens 26 is set to be extremely lower than that of a hard substance such as a piezoelectric body. Therefore, the acoustic lens 26 is made of a material (for example, a soft polymer material) corresponding to the set acoustic impedance. In order to further reduce the attenuation and reflection of ultrasonic waves between the acoustic lens 26 and the acoustic matching layer 25, the acoustic impedance of the portion of the acoustic matching layer 25 that contacts the acoustic lens 26 is the same as that of the acoustic lens 26. It is preferable that they are substantially the same.

Examples of the material forming the acoustic lens 26 include homopolymers such as conventionally known silicone rubber, butadiene rubber, polyurethane rubber, and epichlorohydrin rubber, and ethylene-propylene copolymer rubber obtained by copolymerizing ethylene and propylene. A copolymer rubber or the like can be applied. Of these, it is preferable to use silicone rubber and butadiene rubber.

The I/O signal line 27 is made of a conductor and is electrically connected to the I/O electrode 22 of the piezoelectric element 23 by a conductive adhesive or the like, and ultrasonic diagnosis is performed via the I/O signal line of the cable 3. The drive signal from the apparatus main body 1 is transmitted to the I/O electrode 22, and the reception signal output from the piezoelectric element 23 that receives the ultrasonic wave from the subject is input to the I/O electrode 22 via the I/O signal line of the cable 3. It is transmitted from the O electrode 22 to the ultrasonic diagnostic apparatus main body 1. The GND signal line 28 is made of a conductor, is electrically connected to the GND electrode 24 of the piezoelectric element 23 with a conductive adhesive, etc., and is connected to the ground of the ultrasonic diagnostic apparatus body 1 via the GND signal line of the cable 3. Has been done. The I/O signal line 27, the GND signal line 28, and the thermal deformation section 29 are arranged in parallel with a gap.

The thermal deformation part 29 has a function of being deformed depending on temperature, with its upper end fixed and its lower end released. The heat-deformable part 29 is made of, for example, bimetal made of any one of zinc, copper, nickel, manganese, ferrite, chromium, molybdenum, zirconium, and aluminum. Here, a material obtained by joining two or more kinds of materials having different thermal expansion coefficients is called a bimetal. In the present embodiment, the thermal deformation part 29 has an inner part 29a on the piezoelectric element 23 side and an outer part 29b on the outer side of the piezoelectric element 23, and the inner part 29a and the outer part 29b are joined together. To do.

In this embodiment, a material having a low coefficient of thermal expansion is used for the inner part 29a, and a material having a higher coefficient of thermal expansion is used for the outer part 29b as compared with the inner part 29a. For example, as the inner portion 29a and the outer portion 29b, a nickel ferrite alloy and copper are joined, a chromium ferrite alloy and nickel chromium ferrite are joined, or a nickel ferrite alloy and nickel manganese ferrite alloy are joined. There are things. Any of the above is a combination of a low thermal expansion material and a high thermal expansion material.

Here, the deformation of the thermal deformation unit 29 and its condition will be described with reference to FIG. However, in FIG. 4A and FIG. 4B, the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2 are illustrated for the sake of clarity. 3 is a cross-sectional view illustrating only the GND signal line 28 and the thermal deformation part 29.

When the piezoelectric element is exposed to a high temperature, an electric field is generated due to its pyroelectric effect, and the electric field depolarizes the piezoelectric element and deteriorates its characteristics. However, in the ultrasonic probe 2 of the present embodiment, as shown in FIG. 4A, the I/O signal line 27, the GND signal line 28, and the thermal deformation section 29 form a gap at a normal temperature. The thermal deformation unit 29 is deformed toward the GND signal line 28 side as the temperature of the ultrasonic probe 2 rises. Further, as shown in FIG. 4B, the thermal deformation section 29 brings the GND signal line 28 and the I/O signal line 27 into contact with each other due to the temperature rise, and electrically shorts them.

That is, it is possible to suppress the generation of an electric field generated by the pyroelectric effect of the piezoelectric element that occurs at high temperature, and eliminate the characteristic deterioration of the piezoelectric element 23. That is, the characteristic deterioration of the ultrasonic probe 2 can be eliminated. Although the thermal deformation unit 29 is arranged on the GND signal line 28 side in the present embodiment, the thermal deformation unit 29 may be arranged on the I/O signal line 27 side. Alternatively, the thermal deformation portions may be arranged on both sides of the GND signal line 28 side and the I/O signal line 27 side.

The thermal deformation section 29 deforms as the temperature rises, but this deformation is 10 times or more compared to the deformation due to thermal expansion of the I/O signal line 27 and the GND signal line 28 itself. For example, when the I/O signal line 27 and the GND signal line 28 are made of a metal conductor and each dimension is 0.1 [mm], the I/O signal line 27 and the GND signal line 28 are deformed by thermal expansion. Is about 0.1 [μm], but the gap between the I/O signal line 27 and the GND signal line 28 is set to 1 [μm] or more in consideration of dimensional variation, and the I/O signal line 27 and the GND signal are With the deformation of the line 28 itself due to thermal expansion, the GND signal line 28 and the I/O signal line 27 cannot be brought into contact with each other and electrically short-circuited as the temperature of the ultrasonic probe rises.

In the conventional ultrasonic probe, an abnormality occurs in the polarization of the piezoelectric element due to the pyroelectric effect of the piezoelectric element as the temperature rises. Abnormalities occur in the resonance characteristics of the piezoelectric element, causing unnecessary resonance. However, in the ultrasonic probe 2 of the present embodiment, no abnormality occurs in the polarization of the piezoelectric element even at high temperatures, and unnecessary resonance does not occur.

When the thermal deformation part 29 is a bimetal, as shown in FIGS. 4A and 4B, the distance A between the I/O signal line 27 and the thermal deformation part 29 and the thickness of the GND signal line 28. B, the thickness t of the heat deforming portion 29, the length L of the heat deforming portion 29 in the vertical direction in the figure, and the bending amount D of the heat deforming portion 29. When the bending coefficient K and the temperature range ΔT are set, the bending amount D is expressed by the following equation (1) using the thickness t and the length L of the thermal deformation portion 29.
D=K×ΔT×L×L÷t (1)

Generally, the upper limit of the operating temperature of the ultrasonic probe is 70 [°C]. That is, since the ultrasonic probe is not used at 70[° C.] or higher, it is desirable to short-circuit the I/O signal line 27 and the GND signal line 28 at 70[° C.] or higher. When the I/O signal line 27 and the GND signal line 28 are short-circuited at 70[° C.] or higher, the following is given as an example.
K=15×10 ⁻⁶ (for example, BL-2 (manufactured by Hitachi Metals Neomaterial) is used as the thermal deformation part 29),
ΔT=50° C. (room temperature: 20[° C.], high temperature: 70[° C.]),
L=10 [mm],
It is assumed that t=0.05 [mm].

Here, the difference between the distance A and the distance of the gap between the I/O signal line 27 and the GND signal line 28 is referred to as a distance C. From the formula (1), since the amount of bending D is 1.5 [mm], if the distance C is set to 1.5 [mm] or less, the I/O signal line 27 and the GND signal will be at 70 [° C.] or more. The electric field generated by the pyroelectric effect can be eliminated by short-circuiting with the line 28, and the characteristic deterioration can be suppressed. Therefore, no matter where the thermal deformation section 29 is provided, the GND signal line 28 and the I/O signal line 27 can be brought into contact with each other with the same amount of deformation and electrically short-circuited.

As described above, according to the present embodiment, the ultrasonic probe 2 is electrically connected to the piezoelectric element 23 that transmits and receives ultrasonic waves to and from the subject and the I/O electrode 22 provided on the piezoelectric element 23. The I/O signal line 27 through which the drive signal input to the piezoelectric element 23 and the reception signal output from the piezoelectric element 23 flow, and the GND provided on the piezoelectric element 23 with a gap from the I/O signal line 27. Heat that causes the GND signal line 28 electrically connected to the electrode 24 and the GND signal line 28 to deform at the temperature rise and contact the I/O signal line 27 and the GND signal line 28 at a predetermined temperature (high temperature: for example, 70[° C.]) or more. And a deforming portion 29.

For this reason, it is possible to suppress the generation of an electric field caused by the pyroelectric effect of the piezoelectric element that occurs at high temperature, and there is no need for electrical control for preventing the pyroelectric effect and the cost thereof. Therefore, the characteristics of the piezoelectric element 23 deteriorate due to the pyroelectric effect. Can be easily eliminated, and characteristic deterioration of the ultrasonic probe 2 can be eliminated.

Further, the thermal deformation part 29 is made of bimetal. Therefore, it is possible to suppress the generation of an electric field caused by the pyroelectric effect at a predetermined temperature or higher.

Further, the I/O signal line 27, the GND signal line 28, and the thermal deformation section 29 are arranged in parallel. Therefore, no matter where the thermal deformation section 29 is provided, the GND signal line 28 and the I/O signal line 27 can be brought into contact with each other with the same amount of deformation and electrically short-circuited.

Further, the ultrasonic diagnostic apparatus 100 includes an ultrasonic probe 2, a transmission unit 12 that generates a driving signal and outputs the driving signal to the ultrasonic probe 2, and a reception signal input from the ultrasonic probe 2. An image generation unit 14 that generates ultrasonic image data based on the image data. Therefore, it is possible to eliminate the deterioration of the characteristics of the piezoelectric element 23 and the characteristics of the ultrasonic probe 2 due to the pyroelectric effect, and it is possible to generate ultrasonic image data without deterioration.

(First embodiment)
A first example of the above-described embodiment will be described with reference to FIG. FIG. 5A is a cross-sectional view showing a part of the ultrasonic probe 2A before deformation. FIG. 5B is a sectional view showing a part of the deformed ultrasonic probe 2A.

The apparatus configuration of this example uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above-described embodiment is replaced with the ultrasonic probe 2A of this example. Therefore, the same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 5A, the ultrasonic probe 2A includes a back surface layer 21, an I/O electrode 22A, a piezoelectric element 23, a GND electrode 24A, an acoustic matching layer 25, and an acoustic lens 26. , I/O signal line 27A, GND signal line 28A, cavity portion 30, insulator portion 31, cavity portion 32, and thermal deformation portion 29. The back surface layer 21, the I/O electrode 22A, the piezoelectric element 23, the GND electrode 24A, the acoustic matching layer 25, and the acoustic lens 26 are sequentially stacked from the lower side to the upper side in the front view of the drawing. However, in FIG. 5A and FIG. 5B, the piezoelectric element 23, the I/O electrode 22A, the GND electrode 24A, and the I/O signal line 27A of the ultrasonic probe 2A are shown for the sake of clarity. , A GND signal line 28A, a cavity portion 30, an insulator portion 31, a cavity portion 32, and a thermal deformation portion 29.

The I/O electrode 22A is an I/O electrode formed on the lower surface of the piezoelectric element 23. The GND electrode 24A is a GND electrode formed on the upper surface, the side surface, and a part of the lower surface of the piezoelectric element 23. The I/O electrode 22A and the GND electrode 24A are electrically insulated by the cavity 30.

The I/O signal line 27A is composed of a conductor and is electrically connected to the I/O electrode 22A. The GND signal line 28A is made of a conductor and is electrically connected to the GND electrode 24A. The insulator part 31 is made of an insulator. The I/O signal line 27A is formed on both surfaces of the insulator portion 31, and the GND signal line 28A is formed on one surface of the insulator portion 31. In this way, the insulator portion 31, the I/O signal line 27A, and the GND signal line 28A are stacked. The I/O signal line 27A and the GND signal line 28A are insulated by the cavity portion 30 and the insulator portion 31. The insulator part 31 may be a base part of a flexible printed circuit (FPC) made of an insulator film such as polyimide. In this configuration, the I/O signal line 27A, the insulator portion 31, and the GND signal line 28A function as a flexible board.

The cavity 32 is a gap between the insulators 31 and is arranged at a position where the thermal deformation section 29 short-circuits the GND signal line 28A and the I/O signal line 27A. Since the insulator 31 is provided around the cavity 32, the I/O signal line 27A and the GND signal line 28A are not short-circuited except under high temperature. As shown in FIG. 5B, the I/O signal line 27A and the GND signal line 28A are hollow due to the deformation of the thermal deformation part 29 under high temperature (a predetermined temperature (for example, 70[° C.]) or higher). It is short-circuited by the electrical contact in the part 32.

As described above, according to the present embodiment, the ultrasonic probe 2A includes the insulator part 31 having the I/O signal line 27A and the GND signal line 28A formed on the surface thereof, the I/O signal line 27A and the GND signal line. 28A is insulated, and the cavity 32 in which the I/O signal line 27A and the GND signal line 28A are brought into contact with each other by the deformation of the thermal deformation section 29 is provided. Therefore, the characteristic deterioration of the piezoelectric element 23 and the characteristic deterioration of the ultrasonic probe 2 due to the pyroelectric effect can be eliminated, and the insulation between the I/O signal line 27A and the GND signal line 28A can be improved.

(Second embodiment)
A second example of the above-described embodiment will be described with reference to FIG. FIG. 6A is a sectional view showing a part of the ultrasonic probe 2B before deformation. FIG. 6B is a cross-sectional view showing a part of the ultrasonic probe 2B after the deformation.

The apparatus configuration of this example uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above-described embodiment is replaced with the ultrasonic probe 2B of this example. Therefore, the same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 6A, the ultrasonic probe 2B includes a back surface layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , I/O signal line 27, GND signal line 28B, and thermal deformation unit 29. However, in FIG. 6A and FIG. 6B, the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2B are shown for the sake of clarity. 3 is a cross-sectional view illustrating only the GND signal line 28B and the thermal deformation part 29. FIG.

The GND signal line 28B is made of a conductor and is electrically connected to the GND electrode 24A. The thermal deformation section 29 is made of a conductor, has a function of being deformed by temperature, and functions as a part of the GND signal line 28B.

As shown in FIG. 6B, as the temperature of the ultrasonic probe 2B rises, the thermal deformation section 29 deforms toward the I/O signal line 27, and further rises in temperature (predetermined temperature (for example, 70[ [° C.]) or more), the I/O signal line 27 is contacted, and the I/O signal line 27 and the GND signal line 28B are electrically short-circuited. That is, it is possible to suppress the generation of an electric field generated by the pyroelectric effect of the piezoelectric element 23 that occurs at high temperatures, and eliminate the characteristic deterioration of the piezoelectric element 23. That is, it is possible to eliminate the characteristic deterioration of the ultrasonic probe 2B.

As described above, according to this embodiment, the thermal deformation section 29 is made of a conductor and functions as a part of the GND signal line 28A. Therefore, the characteristic deterioration of the piezoelectric element 23 and the characteristic deterioration of the ultrasonic probe 2B due to the pyroelectric effect can be eliminated, and at the same time, electric conduction becomes possible as a part of the GND signal line 28B, and the ultrasonic probe 2B It is possible to reduce the space.

Although the thermal deformation section 29 is arranged as a part of the GND signal line 28B in the present embodiment, it may be arranged as a part of the I/O signal line. In this configuration, the thermal deformation section 29 comes into contact with the GND signal line at a high temperature. Similarly, the ultrasonic probe may have a configuration including a thermal deformation portion that functions as a part of the GND signal line and a thermal deformation portion that functions as a part of the I/O signal line.

(Third embodiment)
A third example of the above-described embodiment will be described with reference to FIG. FIG. 7A is a cross-sectional view showing a part of the ultrasonic probe 2C before deformation. FIG. 7B is a sectional view showing a part of the deformed ultrasonic probe 2C.

The apparatus configuration of this example uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above-described embodiment is replaced with the ultrasonic probe 2C of this example. Therefore, the same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 7A, the ultrasonic probe 2C includes a back surface layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , I/O signal line 27, GND signal line 28C, thermal deformation section 29, and insulator section 33. However, in FIG. 7A and FIG. 7B, the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2C are illustrated for the sake of clarity. FIG. 28 is a cross-sectional view illustrating only the GND signal line 28C, the thermal deformation section 29, and the insulator section 33.

The GND signal line 28C is made of a conductor and is electrically connected to the GND electrode 24A. The thermal deformation section 29 is made of a conductor, has a function of being deformed by temperature, and also functions as a part of the GND signal line 28C.

The insulator part 33 is, for example, a base part of a flexible substrate made of an insulator film such as polyimide. The GND signal line 28C and the thermal deformation section 29 are formed on the surface of the insulator section 33 on the piezoelectric element 23 side. In this way, the GND signal line 28A or the thermal deformation part 29 and the insulator part 33 are sequentially laminated from the piezoelectric element 23 side to the outside. The insulator part 33 easily holds the thermal deformation part 29, and electrically insulates the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, the I/O signal line 27, and the GND signal line 28C from the outside. It is possible.

As the temperature of the ultrasonic probe 2C rises, the thermal deformation section 29 deforms toward the I/O signal line 27, and further rises in temperature (a predetermined temperature (for example, 70[° C.]) or more) causes I/O. The I/O signal line 27 and the GND signal line 28C come into contact with the signal line 27 and are electrically short-circuited. That is, it is possible to suppress the generation of an electric field generated by the pyroelectric effect of the piezoelectric element 23 that occurs at high temperatures, and eliminate the characteristic deterioration of the piezoelectric element 23. That is, it is possible to eliminate the characteristic deterioration of the ultrasonic probe 2C.

As described above, according to the present embodiment, the ultrasonic probe 2C is arranged outside the I/O signal line 27 and the GND signal line 28C, and the GND signal line 28C is formed on the surface of the piezoelectric element 23 side (inner side). The insulator part 33 is provided. Therefore, the deterioration of the characteristics of the piezoelectric element 23 and the characteristics of the ultrasonic probe 2C due to the pyroelectric effect can be eliminated, and the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal are externally supplied. It enables electrical insulation to the line 27 and the GND signal line 28C.

In the present embodiment, the thermal deformation unit 29 is arranged on the GND signal line 28C side to be a part of the GND signal line 28C (contacts the I/O signal line 27 at high temperature). It may be arranged on the signal line 27 side to be a part of the I/O signal line 27 (contact with the GND signal line 28C under high temperature). Alternatively, the ultrasonic probe is disposed on the GND signal line side and is a part of the GND signal line for thermal deformation, and the ultrasonic probe is disposed on the I/O signal line side for a part of the I/O signal line. It is good also as a structure provided with a part.

(Fourth embodiment)
A fourth example of the above-described embodiment will be described with reference to FIG. FIG. 8A is a cross-sectional view showing a part of the ultrasonic probe 2D before thermal deformation. FIG. 8B is a sectional view showing a part of the ultrasonic probe 2D after thermal deformation.

The apparatus configuration of the present example uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above-described embodiment is replaced with the ultrasonic probe 2D of the present example. Therefore, the same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 8A, the ultrasonic probe 2D includes a back surface layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , I/O signal line 27, GND signal line 28, and thermal deformation unit 29D. However, in FIG. 8A and FIG. 8B, the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 in the ultrasonic probe 2D are illustrated for the sake of clarity. 3 is a cross-sectional view illustrating only the GND signal line 28 and the thermal deformation portion 29D.

The thermal deformation part 29D has a function of deforming depending on temperature, with its upper end being fixed and its lower end being released, and also having a heat dissipation function. When the piezoelectric element 23 transmits ultrasonic waves, heat is generated due to electroacoustic conversion loss. In order to reduce this heat generation, a heat dissipation member made of a material such as metal having high heat conduction is required around the piezoelectric element 23. A metal is mentioned as a material having a high thermal conductivity, and among the metals, copper, molybdenum, aluminum and the like are preferable. Therefore, the thermal deformation part 29D is made of, for example, a bimetal containing the above metal as a heat dissipation member.

Further, the thermal deformation portion 29D has a larger surface area as compared with the thermal deformation portion 29 of the above-mentioned embodiment, and enhances the heat radiation effect. The heat deforming portion 29D can suppress heat generation of the piezoelectric element 23 by a heat radiation function, suppress generation of an electric field generated by the pyroelectric effect of the piezoelectric element 23 that occurs at high temperature, and eliminate deterioration of the characteristics of the piezoelectric element 23. That is, it is possible to eliminate the characteristic deterioration of the ultrasonic probe 2D, and heat is generated when the piezoelectric element 23 transmits an ultrasonic wave, but the generated heat is reduced.

As described above, according to the present embodiment, the thermal deformation portion 29D is made of a material such as metal having high thermal conductivity and has a large plane area, and thus has a heat dissipation function. Therefore, the deterioration of the characteristics of the piezoelectric element 23 and the characteristics of the ultrasonic probe 2D due to the pyroelectric effect can be eliminated, and the piezoelectric element 23 generates heat when transmitting ultrasonic waves, but the generated heat can be reduced. ..

The description in the above-described embodiments and examples is an example of a suitable ultrasonic probe and ultrasonic diagnostic apparatus according to the present invention, and the present invention is not limited to this. For example, a configuration may be used in which at least two of the above-described embodiment and each example are appropriately combined.

Further, the detailed configuration and the detailed operation of each part constituting the ultrasonic diagnostic apparatus 100 in the above-described embodiments and examples can be appropriately changed without departing from the spirit of the present invention.

100 ultrasonic diagnostic apparatus 1 ultrasonic diagnostic apparatus main body 11 operation input unit 12 transmitting unit 13 receiving unit 14 image generating unit 15 image processing unit 15a image memory unit 16 DSC
17 display section 18 control section 2, 2A, 2B, 2C, 2D ultrasonic probe 21 back surface layer 22, 22A I/O electrode 23 piezoelectric element 24, 24A GND electrode 25 acoustic matching layer 26 acoustic lens 27, 27A I/ O signal line 28, 28A, 28B, 28C GND signal line 29, 29D Thermal deformation part 30, 32 Cavity part 31, 33 Insulator part 2a Transducer 3 cable

Claims (9)

A piezoelectric element that transmits and receives ultrasonic waves to and from the subject,
An electrical signal line electrically connected to the first electrode provided on the piezoelectric element, through which a drive signal input to the piezoelectric element and a reception signal output from the piezoelectric element flow,
A ground signal line provided with a gap from the electric signal line and electrically connected to a second electrode provided on the piezoelectric element;
An ultrasonic probe comprising: a thermal deformation unit that is deformed by temperature and contacts the electric signal line and the ground signal line at a predetermined temperature or higher. The ultrasonic probe according to claim 1, wherein the thermal deformation portion is made of a conductor and functions as a part of at least one of the electric signal line and the ground signal line. The ultrasonic probe according to claim 1, wherein at least one of the electric signal line and the ground signal line includes an insulator portion formed on a surface thereof. The electric signal line and the ground signal line are formed on the surface of the insulator part,
The ultrasonic probe according to claim 3, further comprising: a cavity portion that insulates the electric signal line and the ground signal line, and is brought into contact with the electric signal line and the ground signal line by deformation of the thermal deformation portion. .. The ultrasonic wave according to claim 3, wherein the insulator portion is arranged outside the electric signal line and the ground signal line, and the electric signal line or the ground signal line is formed on a surface of the piezoelectric element side. Probe. The ultrasonic probe according to claim 1, wherein the thermal deformation section is made of bimetal. The ultrasonic probe according to any one of claims 1 to 6, wherein the thermal deformation section has a heat dissipation function. The ultrasonic probe according to any one of claims 1 to 7, wherein the electric signal line, the ground signal line, and the thermal deformation section are arranged in parallel. An ultrasonic probe according to any one of claims 1 to 8,
A transmitter that generates the drive signal and outputs the drive signal to the ultrasonic probe;
An ultrasonic diagnostic apparatus comprising: an image generation unit that generates ultrasonic image data based on the received signal input from the ultrasonic probe.

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