JP2009160068A - Ultrasonic probe and ultrasonic diagnostic equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cool an ultrasonic transmitter-receiver by a configuration which can be downsized, in an ultrasonic probe used in ultrasonic diagnostic equipment. <P>SOLUTION: The ultrasonic probe is provided with a piezoelectric element pump 21. The piezoelectric element pump 21 comprises: a pump body 22 composed by connecting two or more stages of piezoelectric elements 22a formed in a cylindrical shape and having electrodes 22b at both ends, having a cap 25 on the input side where a flow passage area is narrower than that of the output side; and a control power source for successively applying a voltage for enlarging the inner diameter of the cylinder and then reducing it from the input side to the output side between the electrodes 22b of the piezoelectric elements 22a of the respective stages. Thus, since the operations (a) and (b) are repeatedly performed and cooled air is supplied to the ultrasonic transmitter-receiver, it is achieved by the configuration which can be substantially downsized compared to a fan or the like. Also, power consumption can be made half or less of that in the case of a cooling fan when obtaining the same cooling effect. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe (probe) used in an ultrasonic diagnostic apparatus and an ultrasonic diagnostic apparatus using the same.

  The ultrasonic diagnostic apparatus is a medical imaging device that non-invasively obtains a tomographic image of a soft tissue in a living body from a body surface by an ultrasonic pulse reflection method. Compared to other medical imaging equipment, this ultrasound diagnostic device has many features such as small size, low cost, high safety without exposure to X-rays, and blood flow imaging using the Doppler effect. It is widely used in the circulatory system (coronary artery of the heart), digestive system (gastrointestinal), internal medicine system (liver, pancreas, spleen), urology system (kidney, bladder), and obstetrics and gynecology.

  An ultrasonic probe used in such a medical ultrasonic diagnostic apparatus generally uses the piezoelectric effect of a piezoelectric ceramic in order to transmit and receive high-sensitivity and high-resolution ultrasonic waves. In this case, a single-type probe that is a single piezoelectric vibrator or an array-type probe in which a plurality of piezoelectric vibrators are arranged one-dimensionally or two-dimensionally is often used as the transmitting piezoelectric vibrator. Since the array type can obtain a fine image, it is widely used for medical purposes. However, with the increase in the number of elements for higher definition, the aperture area needs to be increased. On the contrary, there is a tendency to become narrower from the viewpoint of ease of use. The temperature rises during operation, adversely affecting the sensitivity of the device. Therefore, a device for heat dissipation is necessary.

  Therefore, in Patent Document 1, a plate having good thermal conductivity is attached to each of the piezoelectric vibrator and the circuit board for driving the piezoelectric vibrator, and the generated heat is propagated away from the probe, The other end of the plate is cooled by a fan.

On the other hand, Patent Document 2 discloses that a heat conductive fiber is provided inside a backing material used for the back portion of the piezoelectric vibrator to radiate heat. Patent Document 3 discloses that heat dissipation is improved by mixing a hollow metal material into a waterproof mold material filled between the piezoelectric vibrator and the case.
JP 2007-209699 A JP 2006-129965 A JP 2006-204622 A

  In the prior art disclosed in Patent Document 1, the piezoelectric vibrator can be sufficiently cooled, and hence deterioration of image quality due to a temperature rise of the piezoelectric vibrator can be suppressed. However, even if the probe part, such as a plate with good thermal conductivity and a heat radiating fin, has a size that does not change much from the conventional one, an extra heat dissipation mechanism is required in the surrounding area, which increases the size. is there. On the other hand, in the prior arts of Patent Document 2 and Patent Document 3, there is a problem that the piezoelectric vibrator cannot be sufficiently cooled, and the heat-dissipating housing is overheated.

  An object of the present invention is to provide an ultrasonic probe capable of sufficiently cooling an ultrasonic transmitter / receiver with a structure that can be miniaturized, and an ultrasonic diagnostic apparatus using the ultrasonic probe.

  The ultrasonic probe of the present invention transmits an ultrasonic wave from an ultrasonic transmitter / receiver into a subject, receives an ultrasonic wave reflected in the subject by the ultrasonic transmitter / receiver, and obtains a received signal. In an ultrasonic probe used in an ultrasonic diagnostic apparatus for displaying an image based on the received signal, a plurality of piezoelectric elements formed in a cylindrical shape and having electrodes at both ends are connected to the input side. The inner diameter of the cylinder is between the pump body formed so that the flow area on one end side becomes narrower than the flow area on the other end side on the output side, and the electrodes of the piezoelectric elements in each stage. And a piezoelectric power pump configured to include a control power source for supplying a cooling medium to the ultrasonic wave transmitter / receiver by sequentially applying a voltage to be reduced after being enlarged from the input side to the output side. And

  According to the above configuration, an ultrasonic wave is transmitted from the ultrasonic transceiver into the subject, and the ultrasonic wave reflected in the subject is received by the ultrasonic transceiver to obtain a reception signal, and the reception In an ultrasonic probe used in an ultrasonic diagnostic apparatus for displaying an image based on a signal, a piezoelectric element pump for supplying a cooling medium to the ultrasonic transmitter / receiver is provided. The piezoelectric element pump is formed in a cylindrical shape such as a cylinder and is connected to a plurality of stages of piezoelectric elements having electrodes at both ends, and the flow area on one end side which is the input side is the output side Sequentially applied from the input side to the output side between the pump body, which is formed narrower than the flow path area on the other end side, and the electrodes of the piezoelectric elements at each stage, after the inner diameter of the cylinder is enlarged In the pump body by the voltage application as described above, the input side cylinder first expands, sucks the cooling medium from the input side and the next stage cylinder side, and flows when the cooling medium is reduced. The fluid is pushed out to the cylinder side of the next stage due to the difference in the path area. Thereafter, the piezoelectric element of each stage performs the pumping operation of sucking and pushing out the cooling medium in order from the input side to the output side. That is, the pump body pushes out the cooling medium in the manner of a peristaltic movement of the intestine.

  Therefore, the cooling of the ultrasonic transmitter / receiver can be realized with a configuration that can be significantly reduced in size and consumes less power than a fan or the like.

  In the ultrasonic probe of the present invention, the cooling medium discharged from the piezoelectric element pump is air.

  According to said structure, the said ultrasonic transmitter / receiver is cooled by ventilation.

  Therefore, it is not necessary to provide a special structure for cooling the ultrasonic transmitter / receiver and its surroundings, and the performance of the ultrasonic transmitter / receiver can be improved, and the heated air is discharged outside the probe. Therefore, it is not necessary to provide a configuration for exhaust heat on the probe, and the housing or the like is not overheated.

  Furthermore, in the ultrasonic probe of the present invention, the flow velocity of the air is 10 cm / second or more.

  According to said structure, the temperature rise of the said ultrasonic transmitter / receiver can be suppressed, and a favorable image quality can be maintained.

  In the ultrasonic probe of the present invention, the air is introduced along an electromagnetic wave shielding wall in the probe.

  According to said structure, it becomes unnecessary to provide the air flow path specially.

  Furthermore, the ultrasonic diagnostic apparatus of the present invention is characterized by using the above-mentioned ultrasonic probe.

  According to said structure, the ultrasonic diagnosing device in which a probe can be reduced in size can be implement | achieved.

  As described above, the ultrasonic probe of the present invention is formed in a cylindrical shape and is connected to a plurality of stages of piezoelectric elements having electrodes at both ends, and the flow area on one end side serving as the input side Between the pump body formed to be narrower than the flow path area on the other end side on the output side and the electrodes of the piezoelectric elements at each stage, the voltage to be reduced after the inner diameter of the cylinder is enlarged from the input side A piezoelectric element pump including a control power source for supplying a cooling medium to the ultrasonic transmitter / receiver by sequentially applying to the output side is provided.

  Therefore, the cooling of the ultrasonic transmitter / receiver can be realized with a configuration that can be significantly reduced in size and consumes less power than a fan or the like.

  Furthermore, the ultrasonic diagnostic apparatus of the present invention uses the above-described ultrasonic probe as described above.

  Therefore, an ultrasonic diagnostic apparatus capable of downsizing the probe can be realized.

  Hereinafter, although one embodiment of the present invention is described, the present invention is not limited to this embodiment, and various aspects are included in the present invention.

[Embodiment 1]
FIG. 1 is a cross-sectional view of an ultrasonic probe 1 according to an embodiment of the present invention. The ultrasonic probe 1 is generally attached to the tip of a coaxial cable 2 extending from a diagnostic apparatus main body for displaying a power supply or displaying an image for diagnosis or outputting a print. In addition, the drive circuit boards 4 and 5 are accommodated in the ultrasonic transceiver 10.

  In the housing 3, an opening 6 is formed on the side opposite to the side where the coaxial cable 2 is drawn, and the ultrasonic transceiver 10 faces the subject from the opening 6. An ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like is mounted on the drive circuit boards 4 and 5, and the ultrasonic transceiver 10 is responsive to a drive signal from the diagnostic apparatus body. The ultrasonic wave is transmitted into the subject, and the received signal obtained by receiving the ultrasonic wave reflected in the subject by the ultrasonic transceiver 10 is appropriately processed and output to the diagnostic apparatus body. And displaying an image based on the received signal.

  The ultrasonic transceiver 10 can be configured in various modes. In the example of FIG. 1, two matching layers 12 and 13 are provided on the front surface of the piezoelectric element group 11 in which piezoelectric vibrators are arranged in an array. And a damper 14 is provided on the back surface. As the piezoelectric element group 11, a 32 × 32 element two-dimensional linear array is used. For the piezoelectric vibrator, a green sheet is made from a commercially available PZT powder by a known method, sintered at 1200 ° C., elements are formed into a 32 × 32 array with a dicing saw, and wiring is performed by silver baking. Can be created. As the frequency constant of the PZT, a frequency constant of 2200 Hz · m is used, and thus a resonance frequency of 3.5 MHz is obtained with a thickness of 629 μm. The matching layers 12 and 13 are made of silicon resin, and the damper (backing material) 14 is made by solidifying tungsten powder with epoxy resin. The arrangement of the ultrasonic transceiver 10 configured as described above and the drive circuit boards 4 and 5 described above may be appropriately selected.

  In the ultrasonic probe 1 configured as described above, it should be noted that in the present invention, a piezoelectric element pump 21 for supplying cooling air to the ultrasonic transceiver 10 is provided. The piezoelectric element pump 21 includes a pump body 22 and a control power source 23 that drives the pump body 22. In the present embodiment, the pump main body 22 is provided in a pair at symmetrical positions with the coaxial cable 2 sandwiched between the side of the casing 3 where the coaxial cable 2 is drawn. Corresponding to this, a pair of exhaust holes 28 are provided in the vicinity of the ultrasonic transmitter / receiver 10, and a gap between them is indicated by an arrow with a shield wall 26 for preventing leakage of electromagnetic waves as a flow path. The cooling air flows in The control power supply 23 is realized by the ASIC, FPGA, or the like mounted on the drive circuit board 5.

  2A and 2B are diagrams showing the structure of the pump main body 22, wherein FIG. 2A is a side view and FIG. 2B is a top view. The pump body 22 is formed in a cylindrical shape as shown in FIG. 3, and piezoelectric elements 22a having electrodes 22b at both ends thereof are connected in a plurality of stages (six stages in the example of FIG. 2) and are on the input side. One end side is closed with a cap 25 and the intake hole 24 is formed in the cap 25. The cap 25 includes a cylindrical portion 25a connected to a cylindrical piezoelectric element 22a and an end plate 25b that closes one end portion of the cap 25, and the intake hole 24 is formed in the cylindrical portion 25a (see FIG. In the example of FIG. 2, the flow path area of the pump body 22 is narrower on the intake side than on the exhaust side. The flow passage area is preferably set so that the axial cross-sectional area of the intake hole 24 is less than half of the inner circumference of the piezoelectric element 22a, particularly about a quarter or less. The number of 24 is arbitrary, and the intake hole 24 may be provided in the end plate 25b.

  The piezoelectric element 22a can be molded, for example, by punching and cutting a piezoelectric film. As the material used here, an inorganic material or an organic material exhibiting piezoelectricity can be used. Inorganic materials include PZT (alloy of lead, zirconium and titanium), inorganic materials using niobium and bismuth instead of barium titanate and lead for deleading, polyvinylidene fluoride, fluorine A copolymer of vinylidene fluoride and ethylene trifluoride, polycyanovinylidene, polyurea, or the like can be used. The inorganic material can be molded by firing the precursor formed into a cylindrical shape by punching from the film as described above in the range of 700 ° C to 1300 ° C. In the case of an organic material, it can be formed by cutting and punching after forming into a film.

  Gold, platinum, silver, copper, aluminum, brass, or the like can be selected as the electrode 22b. As the size of the cylinder, it is preferable to select a range in which the outer diameter is 50 μm to 10 mm and the length (height) is 1 μm to 1 cm. As shown in FIG. 4, the electrodes 22b are connected in parallel so that electric fields are generated in opposite directions between the piezoelectric elements 22a cascaded in a straight line.

  Therefore, between the control power source 23 and the electrode 25b of each piezoelectric element 22a, the odd-numbered piezoelectric element and the even-numbered piezoelectric element, which are counted from the intake hole 24, have alternating polarities (180 ° different in phase). When a voltage is applied, the inner diameter of the odd-numbered piezoelectric element is enlarged and the inner diameter of the even-numbered piezoelectric element is reduced as shown in FIG. 5A at a certain timing, and vice versa at the next timing. As shown in b), the inner diameter of the odd-numbered piezoelectric elements is reduced, and the inner diameter of the even-numbered piezoelectric elements is increased. Therefore, each piezoelectric element 22a is thickened and thinned with the position of the electrode 22b as a node, and performs an operation like a peristaltic movement of the intestine. The air is pushed out to the open output side.

  If the resonance frequency of the piezoelectric element 22a is lower than 100 kHz, an audible sound will be heard, which is unfavorable because it gives an unpleasant sound to the examinee. When a piezoelectric element exceeding 100 MHz is formed, the piezoelectric element Therefore, it is not preferable because the pump efficiency is lowered. Therefore, it may be arbitrarily selected between 100 kHz and 100 MHz. Among them, 200 kHz to 20 MHz is preferable, and 400 kHz to 10 MHz is most preferable.

  6 to 8 are graphs showing the experimental results of the inventors of the present application. In the experiment, a PZT piezoelectric element having a frequency constant of 1900 Hz · m is used as the piezoelectric element 22a of the pump body 22, and the length (height) tm is 1.9 mm (1 MHz resonance) and the outer diameter as one unit element. The tz was 5 mm and the inner diameter tex was 4 mm. This element was stacked in six stages, closed by an end plate 25b having four intake holes 24 having an inner diameter of 1 mm, and wiring was applied to each electrode 22b. After wiring, insulation was performed with a polyimide film, and two pump bodies 22 were installed on the ultrasonic probe 1. FIG. 6 shows the change in the suction amount by changing the voltage applied to the piezoelectric element 22a. The drive frequency from the control power supply 23 is 1 MHz, which is the resonance frequency, and shows the change in the outside air suction speed when the drive voltage is changed. As the drive voltage is increased, the suction speed is increased, and the ultrasonic transceiver 10 can be cooled with stronger wind to suppress an increase in temperature. Heat is exhausted from the exhaust hole 28, and the housing 3 is cooled from the inside by the air flowing along the shield wall 26.

  FIG. 7 is a graph showing the measurement result of the temperature rise with respect to the usage time of the ultrasonic transceiver 10. The voltage applied to the piezoelectric element 22a is changed from 0V to 60V. It is understood that the temperature rise is suppressed when the voltage is increased to 60V. Therefore, from FIG. 7, the voltage that can suppress the temperature rise is 60 V, and correspondingly, from FIG. 6 described above, the suction speed that can suppress the temperature rise is 10 cm / second or more.

  Here, FIG. 8 shows a change in image quality when the applied voltage of the piezoelectric element 22a is 0 V, that is, when cooling is not performed. The temperature rise of the ultrasonic transceiver 10 is the same as the graph of FIG. The image quality deteriorates as the temperature rises, and maintains that level when the temperature rise stops. The image quality evaluation in FIG. 8 is performed by visually observing the image displayed on the display panel of the diagnostic apparatus main body. The most excellent image is “excellent”, the excellent image is “good”, and the normal image is “Poor” and poor image quality are evaluated as “poor”. By performing the cooling at the driving voltage of 60 V and the suction speed of 10 cm / second or more as in the present invention, there is almost no temperature rise as shown in FIG. 7, and the image quality as shown in FIG. There was no deterioration, and the phenomenon of resolution, sharpness and speckle noise reduction was observed. In this way, a clear image can be stably obtained by suppressing the temperature rise of the ultrasonic transceiver 10.

  As described above, in the ultrasonic probe 1 of the present embodiment, a plurality of piezoelectric elements 22a that are formed in a cylindrical shape and have the electrodes 22b at both ends are connected to one end side that is the input side. An inner diameter of the cylinder is expanded between a pump body 22 provided with a cap 25 and having a flow passage area narrower than the other end side on the output side, and the electrode 22b of the piezoelectric element 22a of each stage. Then, the piezoelectric element pump 21 including the control power source 23 for supplying cooling air to the ultrasonic transmitter / receiver 10 by sequentially applying the voltage to be reduced from the input side to the output side is provided. Cooling of the transceiver 10 can be realized with a configuration that can be significantly reduced in size compared to a fan or the like. Also, the power consumption can be reduced to less than half that of the cooling fan in obtaining the same cooling effect. Furthermore, the cost can be reduced as compared with a configuration in which a large-area heat radiation fin is provided or air is blown through the coaxial cable 2 from the diagnostic device main body side.

  In addition, it is necessary to provide a special configuration for cooling the ultrasonic transceiver 10 and its periphery by cooling the ultrasonic transceiver 10 by blowing air using the cooling medium discharged from the piezoelectric element pump 21 as air. In addition, the performance of the ultrasonic transmitter / receiver 10 can be improved, and the heated air is exhausted to the outside of the probe 1. Therefore, it is necessary to provide a structure for exhausting heat on the probe 1. And the housing 3 does not overheat. In addition, by introducing the air along the electromagnetic wave shielding wall 26 in the probe 1, it is not necessary to provide a special air flow path.

[Embodiment 2]
FIG. 9 is a side view of a pump main body 32 in an ultrasonic probe according to another embodiment of the present invention. The pump main body 32 is similar to the pump main body 22 shown in FIG. Reference numerals are given and description thereof is omitted. It should be noted that in this pump body 32, an insulating layer 33 is interposed between the electrodes 22b of each piezoelectric element 22a, and a voltage for individually controlling each piezoelectric element 22a is applied from a control power source (not shown). That is. That is, in the pump body 22 described above, the electrodes between the adjacent piezoelectric elements are shared and only voltages having a phase difference of 180 ° are applied, whereas in the pump body 32, the adjacent piezoelectric elements are adjacent. This is because the electrodes between the elements are separated so that each piezoelectric element 22a has a fine phase. Therefore, the peristaltic motion becomes smoother, and the discharge air amount can be increased as compared with the pump main body 32 even when driven under the same conditions.

  Such a piezoelectric element pump can be applied not only to an ultrasonic probe but also to other microfabrication (MEMS) materials. For example, it can be applied to blood circulation pumps in the field of biochemistry, and can also be used in DNA separation circuits for genetic diagnosis. Here, the conventional ultrasonic pump is a type in which an ultrasonic vibrator is brought into contact with a liquid feeding pipe, and the vibration is transmitted to the pipe to feed the liquid. The piezoelectric element pump according to the present embodiment has an advantage that it is not worn and damaged because the liquid feeding pipe is a direct ultrasonic vibrator. An ultrasonic vibrator in which the ultrasonic vibrator is vinylidene fluoride has high chemical resistance, and thus can be applied to a wide range. Although the present invention is based on air cooling, it can also be used for water cooling. In the case of water cooling, it is useful to select a material that hardly reacts with chemicals even if a preservative is added.

  In the scope of the idea of the present invention, those skilled in the art can easily conceive various modified examples and modified examples, and these modified examples and modified examples also belong to the scope of the present invention. It is understood.

1 is a cross-sectional view of an ultrasonic probe according to an embodiment of the present invention. It is a figure which shows the structure of the pump main body which concerns on one Embodiment of this invention. It is a figure of one piezoelectric element which constitutes the pump main part. It is a figure for demonstrating the electrode routing of the said pump main body. It is a figure for demonstrating the motion of the said pump main body. It is a graph which shows the experiment result of this inventor, and shows the change of the suction | inhalation amount when changing the applied voltage to the said pump main body. It is a graph which is an experimental result of this inventor, and shows the measurement result of the temperature rise with respect to the use time of an ultrasonic transceiver. It is a graph which is an experimental result of this inventor, and shows an image quality change at the time of not cooling an ultrasonic transceiver. It is a side view of the pump main body in the ultrasonic probe concerning other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Coaxial cable 3 Housing | casing 4,5 Drive circuit board 6 Opening 10 Ultrasonic transmitter / receiver 11 Piezoelectric element group 12,13 Matching layer 14 Damper 21 Piezoelectric element pump 22 Pump main body 22a Piezoelectric element 22b Electrode 23 Control Power supply 24 Intake hole 25 Cap 26 Shield wall 28 Exhaust hole

Claims (6)

An ultrasonic wave is transmitted from the ultrasonic transmitter / receiver into the subject, the ultrasonic wave reflected in the subject is received by the ultrasonic transmitter / receiver, a received signal is obtained, and an image based on the received signal is displayed. In an ultrasound probe used in an ultrasound diagnostic apparatus,
A plurality of piezoelectric elements that are formed in a cylindrical shape and have electrodes at both ends are connected, and the flow area on one end that is the input side is greater than the flow area on the other end that is the output side The ultrasonic transmission / reception is performed by sequentially applying from the input side to the output side a voltage to be reduced after the inner diameter of the cylinder is enlarged between the narrowly formed pump body and the electrodes of the piezoelectric elements at each stage. An ultrasonic probe comprising a piezoelectric element pump configured to include a control power source for supplying a cooling medium to the child.   The ultrasonic probe according to claim 1, wherein the cooling medium discharged from the piezoelectric element pump is air.   The ultrasonic probe according to claim 2, wherein a flow velocity of the air is 10 cm / second or more.   The ultrasonic probe according to claim 2, wherein the air is introduced along an electromagnetic wave shielding wall in the probe.   An ultrasonic diagnostic apparatus using the ultrasonic probe according to any one of claims 1 to 4. A plurality of piezoelectric elements that are formed in a cylindrical shape and have electrodes at both ends are connected, and the flow area on one end that is the input side is greater than the flow area on the other end that is the output side A pump body formed narrowly;
A control power supply for supplying a cooling medium to the ultrasonic transceiver by sequentially applying a voltage to be reduced after the inner diameter of the cylinder is enlarged between the electrodes of the piezoelectric elements at each stage from the input side to the output side. And a piezoelectric element pump.

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