JP2011050571A - Ultrasonic probe, ultrasonograph, and ultrasonic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the transmission and reception sensitivity of an ultrasonic transducer by eliminating the voltage drop of a detection signal due to cable transmission. <P>SOLUTION: The ultrasonic transducer (UT) 27 includes a first piezoelectric body 35, a second piezoelectric body 36, and first to fourth electrodes 37 to 40. Respective electrodes 37 to 40 are connected with first to fifth switches (SWa to SWe) 41 to 45. The first and second piezoelectric bodies 35 and 36 are connected in parallel in ultrasonic transmission, and connected in series in receiving reflected waves. A reception amplifier 47 receives the reflected waves and amplifies a detection signal output from the first and second piezoelectric bodies 35 and 36. The reception amplifier 47 is directly connected with the second electrode 38 without interposing the transmission line of electric capacity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Medical diagnosis using an ultrasonic probe is actively performed. An ultrasonic transducer (hereinafter abbreviated as UT) is disposed at the tip of the ultrasonic probe. The UT includes a backing material, a piezoelectric body and electrodes sandwiching the piezoelectric body, an acoustic matching layer, and an acoustic lens. The subject (human body) is irradiated with ultrasonic waves from the UT, and the reflected wave from the subject is received by the UT. An ultrasonic image is obtained by electrically processing the detection signal output in this way with an ultrasonic observer.

  It is also possible to obtain an ultrasonic tomographic image by irradiating while scanning with ultrasonic waves. As a method for obtaining an ultrasonic tomographic image, a mechanical scan scanning method in which a UT is mechanically rotated, rocked, or slid, or a plurality of UTs arranged in an array (hereinafter referred to as a UT array) and driven UTs are arranged. An electronic scan scanning method that is selectively switched by an electronic switch or the like is known.

  There is an increasing demand for observing deeper portions of a subject with high-definition images. In order to meet this requirement, it is necessary to increase the transmission / reception sensitivity of the UT. Conventionally, as a measure for increasing the transmission / reception sensitivity of the UT, material selection and optimization of the UT member have been performed. For example, a 1-3 composite piezoelectric body, a single crystal piezoelectric body (PMN-PT, PZN-PT, etc.), a laminated piezoelectric body is used, or sound wave attenuation of an acoustic matching layer and an acoustic lens is reduced. As another countermeasure, it is conceivable to increase the transmission power of the ultrasonic wave by increasing the voltage applied to the UT.

  However, the former material selection and optimization measures have felt that improvement has been striking, and the effects are at the peak. Under the present circumstances, a dramatic improvement in the transmission / reception sensitivity of UT cannot be expected. Further, the latter measure for increasing the transmission power of ultrasonic waves is not preferable in view of the influence on the human body.

  Patent Document 1 discloses an ultrasonic probe in which a piezoelectric electrode is divided into a plurality of parts. Since the electrodes are divided, one piezoelectric body can be handled as a plurality of piezoelectric bodies. When transmitting ultrasonic waves, connect multiple piezoelectric bodies in parallel, and when receiving reflected waves, connect them in series. Improvement has been achieved.

  By the way, for example, an abdominal ultrasound probe having a capacitance Cz = 150 pF per UT is considered as an example. Now, the capacitance of the cable that transmits the detection signal output by the UT to the ultrasonic observation device is Cc = 200 pF (assuming that a cable with a capacitance of 100 pF per meter and a length of 2 m is used), and the input resistance Is infinite, and the detection signal is received by the receiving amplifier of the ultrasonic observer. The voltage of the detection signal output from the UT is Vut. At this time, the voltage Va of the detection signal observed at the input terminal of the receiving amplifier is Va = 150 / (200 + 150) · Vut = 0.43Vut from Va = Cz / (Cc + Cz) · Vut.

  When, for example, two piezoelectric bodies are connected in series when a reflected wave is received as in Patent Document 1, the combined capacitance Cg is ¼ · Cz. The voltage Vb of the detection signal observed at the input terminal of the receiving amplifier at this time is Vb = n · {Cg / (Cg + Cz) · Vut} (n is the number of piezoelectric bodies connected in series). {37.5 / (37.5 + 200) · Vut} = 0.32 Vut.

  The voltage Vb in the case where a plurality of piezoelectric bodies are connected in series is lower than the voltage Va (= 0.43 Vut) of the detection signal observed at the input terminal of the receiving amplifier when the plurality of piezoelectric bodies are not connected in series. Even when a plurality of piezoelectric bodies are connected in series to improve reception sensitivity, a voltage drop occurs due to a decrease in capacitance. In Patent Document 1, an impedance converter is connected between the UT and the cable in order to reduce the influence of the voltage drop of the detection signal caused by the combined capacitance being reduced by connecting a plurality of piezoelectric bodies in series. ing.

Japanese Patent Laid-Open No. 03-110998

  However, it is difficult to avoid the voltage drop of the detection signal due to cable transmission only by connecting an impedance converter between the UT and the cable as in Patent Document 1 to achieve impedance matching.

  The present invention has been made in view of the above background, and an object of the present invention is to eliminate a voltage drop of a detection signal due to cable transmission and further improve transmission / reception sensitivity of an ultrasonic transducer.

  An ultrasonic probe according to the present invention is connected to an ultrasonic transducer having a plurality of piezoelectric bodies arranged in a direction parallel to a transmission / reception surface of ultrasonic waves and reflected waves, and to each electrode sandwiching the plurality of piezoelectric bodies, and includes a plurality of piezoelectric elements. A changeover switch for switching the connection of the body in parallel or in series, a drive control means for operating the changeover switch so that a plurality of piezoelectric bodies are connected in parallel at the time of transmission of ultrasonic waves and connected in series at the time of reception of reflected waves; An amplifier that receives a reflected wave and amplifies a detection voltage output from a piezoelectric body, and includes an amplifier that is directly connected to an electrode of the piezoelectric body without passing through a capacitive transmission line.

  It is preferable that the amplifier is disposed on a side surface perpendicular to the wave transmitting / receiving surface of the base material on which the piezoelectric body of the ultrasonic transducer is placed. In this case, the amplifier is mounted on a circuit board, and the circuit board is disposed on a side surface perpendicular to the wave transmitting / receiving surface of the base material. The changeover switch may be mounted on the circuit board together with the amplifier.

  The amplifier is preferably embedded in a base material on which the piezoelectric body of the ultrasonic transducer is placed. In this case, the amplifier is mounted on a circuit board, and the circuit board is embedded in the base material. The changeover switch may be mounted on the circuit board together with the amplifier.

  It is preferable that a cooling mechanism for cooling the driving heat of the amplifier is provided on the base material. The base material is a so-called backing material or a pedestal on the back side of the backing material.

  The amplifier may be a voltage feedback type or a charge storage type.

  The ultrasonic transducer has a plurality of piezoelectric bodies having different ultrasonic transmission capabilities and reflected wave reception sensitivities, and an electrode including a combined electrode that also serves as one upper surface electrode and the other lower surface electrode of an adjacent piezoelectric body, A plurality of piezoelectric bodies are connected in series by the electrodes. The drive control means applies a drive voltage to electrodes other than one piezoelectric element via an electrode to generate an ultrasonic wave, receives a reflected wave, and detects a detection voltage output from the piezoelectric elements for all the piezoelectric elements. The changeover switch is operated so that the minute addition is performed.

  Note that “a plurality of piezoelectric bodies having different ultrasonic transmission capabilities and reflected wave reception sensitivities” means that each of the plurality of piezoelectric bodies is different from each other and at least one of the plurality of piezoelectric bodies. Includes cases that are different from others.

The plurality of piezoelectric bodies are polarized in the same direction parallel to the normal line of the transmission / reception surface of ultrasonic waves and reflected waves. In addition, the plurality of piezoelectric bodies have different equivalent piezoelectric constants d ₃₃ , voltage output coefficients g ₃₃ , or different area ratios of the transmission and reception surfaces of ultrasonic waves and reflected waves.

  The first piezoelectric body at one end of the series connection and the serial connection having a lower ultrasonic wave transmission capability and higher reflected wave reception sensitivity than the first piezoelectric body, and a lower area ratio of the transmission / reception surface of the ultrasonic wave and reflected wave It is preferable that a second piezoelectric body at the other end of the first piezoelectric element and a pulsar connected to an electrode that is not a dual-purpose electrode of the first piezoelectric body to supply a driving voltage. The amplifier is connected to an electrode that is not a dual-purpose electrode of the second piezoelectric body, and the changeover switch turns on / off connection of the first piezoelectric body, the electrode of the second piezoelectric body, the pulser, and the amplifier. Switch. The drive control means operates the changeover switch so that a drive voltage is applied to a piezoelectric body other than the second piezoelectric body and a sum of detection signals from all the piezoelectric bodies is input to the amplifier.

It said second piezoelectric body, wherein the low equivalent piezoelectric constant d ₃₃ than the first piezoelectric element, a high voltage output coefficient g _33, the area ratio of the transmitting and receiving surface of the ultrasonic and the reflected wave is small. For example, the first piezoelectric body is a soft relaxor system, and the second piezoelectric body is a hard piezoelectric ceramic.

  The ultrasonic transducers are arranged in a plurality of arrays. In this case, a pulser that supplies a driving voltage to the piezoelectric body, scanning control means that drives the pulser to scan ultrasonic waves, and an A / D converter that uses the detection voltage amplified by the amplifier as a digital detection signal And signal processing means for executing signal processing for generating an ultrasonic image from the detection signal, and main control means for comprehensively controlling each part.

  You may provide the multiplexer which selectively switches the said ultrasonic transducer which transmits / receives an ultrasonic wave and a reflected wave. Furthermore, a power supply unit that supplies power to each unit and a wireless transmission unit that wirelessly transmits a detection signal after signal processing to an ultrasonic observation device that displays an ultrasonic image may be provided.

  An ultrasonic diagnostic apparatus of the present invention is connected to an ultrasonic transducer having a plurality of piezoelectric bodies arranged in a direction parallel to a transmission / reception surface of ultrasonic waves and reflected waves, and each electrode sandwiching the plurality of piezoelectric bodies, A changeover switch for switching the connection of the piezoelectric bodies in parallel or in series, and a drive control means for operating the changeover switch so that a plurality of piezoelectric bodies are connected in parallel when transmitting ultrasonic waves and connected in series when receiving reflected waves; An ultrasonic probe that receives a reflected wave and amplifies a detection voltage output from the piezoelectric body, and includes an electrode directly connected to the piezoelectric body electrode without passing through a capacitive transmission line; The ultrasonic probe is connected to the ultrasonic probe and displays an ultrasonic image.

  The ultrasonic transducer of the present invention includes a piezoelectric body that transmits and receives ultrasonic waves and reflected waves, a base material on which the piezoelectric body is placed, and embedded in the base material, and receives reflected waves from the piezoelectric body. And an amplifier that amplifies the output detection voltage.

  According to the present invention, when transmitting ultrasonic waves, a plurality of piezoelectric bodies are connected in parallel, and when receiving reflected waves, they are connected in series so that the sum of detection signals is input to the receiving amplifier, and the receiving amplifier is connected to the piezoelectric transducer piezoelectric transducer. Since it is directly connected to the body electrode, the voltage drop of the detection signal due to cable transmission is eliminated, and the transmission / reception sensitivity of the ultrasonic transducer can be further improved.

It is an external view which shows the structure of an ultrasonic diagnosing device. It is a perspective view which shows the structure of an ultrasonic transducer array. It is an expanded sectional view which shows the structure of an ultrasonic transducer. It is explanatory drawing which shows the equivalent circuit of the ultrasonic transducer at the time of (A) at the time of transmission of an ultrasonic wave, and (B) at the time of reception of a reflected wave. It is a block diagram which shows the electric constitution of an ultrasonic diagnosing device. It is an expanded sectional view which shows the structure of the ultrasonic transducer which has arrange | positioned the flexible printed circuit board with a receiving amplifier on the side surface of the backing material. It is an expanded sectional view which shows the structure of the ultrasonic transducer which has arrange | positioned receiving amplifier inside the backing material. It is an expanded sectional view which shows the structure of the ultrasonic transducer which has arrange | positioned the flexible printed circuit board with a receiving amplifier inside the backing material. It is an expanded sectional view showing the composition of the ultrasonic transducer which provided the cooling mechanism. It is a block diagram which shows the electrical constitution of the ultrasonic diagnostic apparatus of another example. It is a block diagram which shows another example which connected the multiplexer. It is an expanded sectional view showing the composition of the ultrasonic transducer which has a plurality of piezoelectric bodies from which the transmission capacity of ultrasonic waves and the reception sensitivity of reflected waves differ. It is explanatory drawing which shows the equivalent circuit of the ultrasonic transducer shown in FIG. 12 at the time of (A) at the time of transmission of an ultrasonic wave, and (B) at the time of reception of a reflected wave.

  In FIG. 1, the ultrasonic diagnostic apparatus 2 includes a portable ultrasonic observation device 10 and an external ultrasonic probe 11. The portable ultrasonic observation device 10 includes an apparatus main body 12 and a cover 13. On the upper surface of the apparatus body 12, an operation unit 14 provided with a plurality of buttons and a trackball for inputting various operation instructions to the portable ultrasonic observation device 10 is arranged. A monitor 15 for displaying various operation screens including an ultrasonic image is provided on the inner surface of the cover 13.

  The cover 13 is attached to the apparatus main body 12 via a hinge 16, and the opening position shown in the figure that exposes the operation unit 14 and the monitor 15, the upper surface of the apparatus main body 12, and the inner surface of the cover 13 face each other. It is rotatable between a closed position (not shown) that covers and protects the unit 14 and the monitor 15. A grip (not shown) is attached to the side surface of the apparatus main body 12, and the portable ultrasonic observer 10 can be carried with the apparatus main body 12 and the cover 13 closed. A probe connecting portion 17 to which the ultrasonic probe 11 is detachably connected is provided on the other side surface of the apparatus main body 12.

  The ultrasonic probe 11 includes a scanning head 18 held by an operator and applied to a subject, a connector 19 connected to the probe connecting portion 17, and a cable 20 connecting them. An ultrasonic transducer array (hereinafter abbreviated as UT array) 21 is built in the tip of the scanning head 18.

  In FIG. 2, the UT array 21 includes a backing material 26, an ultrasonic transducer (hereinafter abbreviated as UT) 27, acoustic matching layers 28 a and 28 b, and an acoustic lens 29 on a flat base 25 made of glass-epoxy resin or the like. Are sequentially stacked.

  The backing material 26 is made of, for example, epoxy resin or silicone resin, and absorbs ultrasonic waves emitted from the UT 27 toward the pedestal 25 side. The backing material 26 has a convex shape in which a cross section perpendicular to the elevation direction (hereinafter abbreviated as EL direction) is formed in a substantially bowl shape (see also FIG. 1).

  The UT 27 has a long strip shape in the EL direction, and is arranged at a plurality of equal intervals in the azimuth direction (hereinafter abbreviated as AZ direction) orthogonal to the EL direction. Fillers 30 are filled in the gaps of the respective UTs 27 and the periphery thereof.

  The acoustic matching layers 28a and 28b are provided to alleviate the difference in acoustic impedance between the UT 27 and the subject. The acoustic lens 29 is made of silicone resin or the like, and focuses an ultrasonic wave emitted from the UT 27 toward an observation site in the subject. The acoustic lens 29 may not be provided, and a protective layer may be provided instead of the acoustic lens 29. A delay line may be provided between the first electrode 37 and the pulser 46 described later, and the ultrasonic wave may be electrically focused by shifting the timing at which the excitation pulse is applied to the UT 27.

  In FIG. 3, the UT 27 includes a first piezoelectric body 35, a second piezoelectric body 36, and first, second, third, and fourth electrodes 37, 38, 39, and 40. (The pedestal 25, the acoustic matching layers 28a and 28b, and the acoustic lens 29 are not shown).

  The first and second piezoelectric bodies 35 and 36 are piezoelectric ceramics made of the same material such as PZT (lead zirconate titanate). Both the first and second piezoelectric bodies 35 and 36 are polarized in the same direction (from the bottom to the top indicated by arrows).

  The first and second piezoelectric bodies 35 and 36 are divided by a line parallel to the AZ direction. The lengths of the first and second piezoelectric bodies 35 and 36 in the EL direction are the same, and therefore the area of the wave transmitting / receiving surface which is the upper surface thereof is also the same.

  The first and second electrodes 37 and 38 are upper surface electrodes of the first and second piezoelectric bodies 35 and 36, respectively. The third and fourth electrodes 39 and 40 are first and second piezoelectric bodies 35 and 36, respectively. The lower surface electrode. The first and second electrodes 37 and 38 are bent at a substantially right angle at the divided portions of the first and second piezoelectric bodies 35 and 36, penetrate the inside of the backing material 26 and the pedestal 25, and are provided up to the lower surface of the pedestal 25. It has been. The third and fourth electrodes 39 and 40 extend downward from the upper surfaces of the first and second piezoelectric bodies 35 and 36 along the side surfaces of the backing material 26 and the pedestal 25, and are provided up to the lower surface of the pedestal 25. Fillers 30 are filled in the outer surfaces of the first and second piezoelectric bodies 35 and 36 and the divided portions of the first and second piezoelectric bodies 35 and 36.

  First, second, third, fourth, and fifth switches (hereinafter referred to as SWa, SWb, SWc, SWd, and SWe) 41, 42, 43, 44, and 45 are provided on the first to fourth electrodes 37 to 40, respectively. Are connected to each other. More specifically, SWa 41 is connected to one end of the first electrode 37, SWb 42 is connected to one end of the second electrode 38, and SWc 43 is connected to the other end of the first and second electrodes 37, 38, respectively. SWd44 and one end of the fourth electrode 40 are connected to one end of SWd44. SWc-SWe43-45 are distribute | arranged to the lower surface of the base 25, and are connected with the extension part of each electrode 37-40 of a lower surface.

  SWa41 and SWb42 turn on / off the connection of the first electrode 37 and the pulser 46, and the second electrode 38 and the voltage feedback type or charge storage type reception amplifier 47, respectively. SWc43 and SWd44 are bifurcated switches. SWc43 connects the first electrode 37 and the second electrode 38 or the fourth electrode 40 so that they can be selected. SWd44 can select the third electrode 39 and the fourth electrode 40 or the ground. Connect to. SWc43 and SWd44 have a common output terminal connected to the fourth electrode 40, and constitute a switch with two inputs and three outputs. The SWe 45 turns on / off the connection between the fourth electrode 40 and the ground. The second electrode 38, the SWb 42, and the reception amplifier 47 are directly connected to each other without passing through the capacitive transmission line.

  As shown in Table 1, the selection states of SWa to SWe41 to 45 change depending on whether the ultrasonic wave is transmitted or the reflected wave is received. When transmitting an ultrasonic wave, SWa41 is turned on and SWb42 is turned off. SWc43 is tilted to the second electrode 38 side, and SWd44 is tilted to the fourth electrode 40 side. Also, SWe45 is turned on. This is the same as the state shown in FIG. An equivalent circuit in this case is as shown in FIG. That is, the pulser 46, the first electrode 37, and the second electrode 38 are connected, and the third electrode 39, the fourth electrode 40, and the ground are connected. Then, an excitation pulse (driving voltage) from the pulser 46 is applied to the first and second piezoelectric bodies 35 and 36 sandwiched between the first and second electrodes 37 and 38 and the third and fourth electrodes 39 and 40. Ultrasonic waves (indicated by dotted arrows) are emitted from the upper surfaces of the first and second piezoelectric bodies 35 and 36.

  On the other hand, when the reflected wave is received, SWa41 is turned off and SWb42 is turned on. SWc43 is tilted to the fourth electrode 38 side, and SWd44 is tilted to the ground side. Also, SWe45 is turned off. In the equivalent circuit in this case, as shown in FIG. 4B, the second electrode 38 and the reception amplifier 47 are connected. The first electrode 37 and the fourth electrode 38 are connected, and the third electrode 39 and the ground are connected. The first and second piezoelectric bodies 35 and 36 are connected in series to the reception amplifier 47 by the electrodes 37 to 40. When reflected waves (indicated by dotted arrows) are incident on the upper surfaces of the first and second piezoelectric bodies 35 and 36, detection signals (detection voltages) corresponding to the reflected waves are output from the first and second piezoelectric bodies 35 and 36. . Since the first and second piezoelectric bodies 35 and 36 are both polarized in the same direction indicated by the arrows, the detection signals do not cancel out with the same polarity. Further, since the first and second piezoelectric bodies 35 and 36 are connected in series, the detection signal input to the reception amplifier 47 via the second electrode 38 and SWb 42 is the first and second piezoelectric bodies 35 and 36. Is the sum of the detection signals output from.

  In FIG. 5, a receiver 50 is connected to the reception amplifier 47, and an A / D converter (hereinafter abbreviated as A / D) 51 is connected to the receiver 50. The receiver 50 receives the detection signal amplified by the reception amplifier 47. The A / D 51 performs digital conversion on the detection signal from the receiver 50 and digitizes the detection signal. Only one set of the receiver 50, the A / D 51, the pulsar 46, and the reception amplifier 47 is shown here, but one set is provided for each UT 27, that is, the number of the UTs 27. .

  The pulser 46 is driven and controlled by the scanning control unit 53 under the control of the CPU 52. The scanning control unit 53 selects the pulsar 46 to be driven from the plurality of pulsars 46, and sequentially switches them at a predetermined time interval. Specifically, for example, when 128 UTs 27 are arranged, among the 128 UTs 27, the adjacent 48 UTs 27 are selected as one block so that each UT 27 is driven with an arbitrary delay difference. The UT 27 to be driven is shifted by one to several for each transmission / reception of the ultrasonic wave and the reflected wave. The pulser 46 transmits an excitation pulse for causing the UT 27 to generate an ultrasonic wave based on the drive signal transmitted from the scanning control unit 53.

  Further, the scanning control unit 53 controls the switching operation of SWa to SWe41 to 45.

  The A / D 51 is connected to a beam former (hereinafter abbreviated as BF) 54. The BF 54 performs a phase matching operation on the detection signal digitized by the A / D 51. The detection log compression circuit 55 detects the amplitude of the detection signal output from the BF 54 and performs log compression. The detection signal output from the detection log compression circuit 55 is temporarily stored in a memory (not shown).

  The portable ultrasonic observer 10 has a digital scan converter (hereinafter abbreviated as DSC) 60. The DSC 60 receives a digital detection signal from the memory of the ultrasonic probe 11 via the connector 19, the probe connection unit 17, and the like. The DSC 60 converts the detection signal into a television signal under the control of the CPU 61. The television signal converted by the DSC 60 is D / A converted by a D / A converter (not shown) and displayed on the monitor 15 as an ultrasonic image.

  The CPU 61 comprehensively controls the operation of each part of the portable ultrasonic observation device 10. The CPU 61 operates each unit based on an operation input signal from the operation unit 14. Further, the CPU 61 controls the power supply unit 62 to supply power to the ultrasonic probe 11.

  The operation of the ultrasonic diagnostic apparatus 2 having the above configuration will be described. First, the connector 19 of the ultrasonic probe 11 is inserted and fixed to the probe connecting portion 17 of the portable ultrasonic observation device 10 to obtain an electrical mechanical connection between the portable ultrasonic observation device 10 and the ultrasonic probe 11. Then, the operation unit 14 is operated to turn on the power of the portable ultrasonic observation device 10, and power is supplied from the power supply unit 62 to the ultrasonic probe 11. The surgeon makes a diagnosis by observing the ultrasonic image displayed on the monitor 15 of the portable ultrasonic observation device 10 while pressing the scanning head 18 of the ultrasonic probe 11 against the subject.

  In the ultrasonic probe 11, an excitation pulse is transmitted from the pulser 46 selected by the scanning control unit 53 to the UT 27, and the subject is irradiated with ultrasonic waves from the UT 27. The pulser 46 driven by the scanning control unit 53 is sequentially switched every time transmission / reception of ultrasonic waves and reflected waves is performed. Thereby, ultrasonic waves are scanned on the subject.

  At this time, the scanning control unit 53 turns on SWa41 of the UT 27 that emits ultrasonic waves and turns off SWb42. Further, SWc43 is tilted toward the second electrode 38, and SWd44 is tilted toward the fourth electrode 40. Further, SWe45 is turned on. The excitation pulse from the pulser 46 is applied to the first and second piezoelectric bodies 35 and 36 via the electrodes 37 to 40, and ultrasonic waves are emitted from the first and second piezoelectric bodies 35 and 36 toward the subject. It is done.

  The ultrasonic waves emitted from the first and second piezoelectric bodies 35 and 36 are reflected by the subject, and a detection signal corresponding to the reflected waves is output from the UT 27. At this time, the scanning control unit 53 turns off SWa41 of the UT 27 that receives the reflected wave, and turns on SWb42. Further, SWc43 is tilted to the fourth electrode 38 side, and SWd44 is tilted to the ground side. Furthermore, SWe45 is turned off. The first and second piezoelectric bodies 35 and 36 are connected in series to the reception amplifier 47 by the electrodes 37 to 40. The reception amplifier 47 receives the sum of the detection signals output from the first and second piezoelectric bodies 35 and 36.

  The detection signal from the UT 27 is amplified by the reception amplifier 47, received by the receiver 50, A / D converted by the A / D 51, and digitized. The detection signal digitized by the A / D 51 is sent to the BF 54, subjected to phase matching calculation by the BF 54, further detected and Log compressed by the detection Log compression circuit 55, and then temporarily stored in the memory.

  The detection signal after detection and log compression is transmitted to the DSC 60 of the portable ultrasonic observation device 10 via the connector 19 and the probe connection unit 17 and the like, and is converted into a television signal by the DSC 60. The television signal converted by the DSC 60 is D / A converted and displayed on the monitor 15 as an ultrasonic image.

  As described above, when transmitting ultrasonic waves, the first and second piezoelectric bodies 35 and 36 are connected in parallel, and when receiving reflected waves, they are connected in series and the sum of detection signals is input to the reception amplifier 47. Transmission / reception sensitivity can be improved. Since the reception amplifier 47 is disposed in the immediate vicinity of the UT 27 and the second electrode 38, the SWb 42, and the reception amplifier 47 are directly connected to each other, a voltage drop due to the transmission line can be reduced.

  In the above-described embodiment, the UT 27 having the two piezoelectric bodies of the first and second piezoelectric bodies 35 and 36 is illustrated, but the number of piezoelectric bodies may be two or more. As the number of piezoelectric bodies increases, the combined capacitance when connected in series further decreases. For this reason, it is necessary to further reduce the voltage drop due to the transmission line. As a countermeasure against this, it is conceivable to arrange the reception amplifier 47 closer to the UT 27.

  The UTs 70, 75, and 80 shown in FIGS. 6 to 8 are provided with measures for further approaching the reception amplifier 47. 6 to 8 are different from the above embodiment only in the structure, and the selection states of SWa to SWe 41 to 45 at the time of transmission of ultrasonic waves and reception of reflected waves are the same as those in Table 1. .

  The UT 70 shown in FIG. 6 has a flexible printed circuit board (hereinafter referred to as FPC) 71 made of polyimide or the like attached to its side surface. The FPC 71 is arranged from the side surface of the filler 30 filling the side surface of the second piezoelectric body 35 to the upper side surface of the backing material 26.

  The second electrode 38 is formed longer toward the side surface than in the above embodiment, and one end of the second electrode 38 is bent downward in the shape of a hand. The FPC 71 is connected to the hand-shaped bent portion of the second electrode 38 and the ground with solder or the like. As indicated by a dotted circle, the SWB 42 and the reception amplifier 47 are mounted on the FPC 71. As in the above embodiment, the SWb 42 is connected to the second electrode 38, and the ground terminal of the reception amplifier 47 is connected to the ground. In the figure, only one SWb 42 of the UT 70 and the reception amplifier 47 are mounted on one FPC 71, but actually, the SWb 42 and the reception amplifier 47 corresponding to the number of UTs 70 are mounted on one FPC 71.

  Since the FPC 71 on which the reception amplifier 47 is mounted is attached to the side surface of the backing material 26, the reception amplifier 47 can be disposed closer to the UT, and the voltage drop due to the transmission line can be further reduced.

  In the UT 75 shown in FIG. 7, SWa to SWe 41 to 45 and the reception amplifier 47 are embedded in the backing material 26. The first and second electrodes 37 and 38 do not penetrate through the backing material 26 and the pedestal 25 as in the above embodiment, and are provided only up to the upper surface of the backing material 26. The first and second electrodes 37 and 38 are connected to the SWc 43 near the upper surface of the backing material 26. Similar to the UT 70 of FIG. 6, the second electrode 38 is formed long toward the side surface, one end of which is bent downward in the shape of a scissors, and further extended toward the upper side surface of the backing material 26. It is formed in a substantially U-shaped cross section. The SWb 42 is connected to the extended portion of the second electrode 38.

  Unlike the above-described embodiment, the third and fourth electrodes 39 and 40 do not extend to the lower surface of the pedestal 25 and are provided only to the vicinity of the upper portion of the backing material 26. The third and fourth electrodes 39 and 40 are connected to the SWd 44 and the SWe 45 at the upper part of the backing material 26.

  Since the receiving amplifier 47 is embedded in the backing material 26, the voltage drop due to the transmission line can be further reduced as in the case of FIG. In the case of FIG. 6, the UT is slightly enlarged in the EL direction by the amount of the FPC 71 disposed on the side surface of the backing material 26. However, in this example, the size can be reduced.

  A UT 80 shown in FIG. 8 is an example in which the SWa to SWe 41 to 45 and the reception amplifier 47 embedded in the backing material 26 in FIG. 7 are integrated in one FPC 81. Since the configuration of the electrodes and the like is the same as that in FIG. In this case as well as the FPC 71 of FIG. 6, only one is drawn in the figure, but in reality, the SWAs to SWe 41 to 45 and the reception amplifiers 47 corresponding to the number of UTs 80 are mounted on one FPC 81. Since the degree of integration of each part is increased, the UT array can be made more compact than in the case of FIG. 7 in which each part is dissipated, and handling during manufacture of the UT array is facilitated.

  6 to 8, the receiving amplifier 47 and the like are arranged on the side surface of the backing material 26 or embedded therein, but the receiving amplifier 47 has a problem of driving heat. In the case of FIG. 6, since it is arranged on the side surface of the backing material 26, a slight heat dissipation effect can be expected as compared with the cases of FIGS. 7 and 8. There is concern about the negative effects of

  Therefore, as shown in FIG. 9, a conduit 86 through which a liquid refrigerant 85 such as cooling water flows is piped in the vicinity of the FPC 81 in the backing material 26. The pipe 86 is connected to a cooler and a circulation pump (both not shown). The liquid refrigerant 85 that has taken away the drive heat of the reception amplifier 47 of the FPC 81 is cooled by the cooler, and the pipe 86 is connected by the circulation pump. Circulate inside. In this way, it is possible to cool the drive heat caused by mounting the reception amplifier 47 with high integration, and to eliminate the adverse effects thereof. In FIG. 9, the UT 80 in FIG. 8 is taken as an example, but the above cooling mechanism may be provided in the UTs 70 and 75 in FIGS.

  Although the examples of FIGS. 6 and 7 have been described individually, some of the UTs have the receiving amplifier 47 disposed on the side of the backing material 26, and others are embedded in the backing material 26. These may be combined. In addition, although the example in which the reception amplifier 47 and the like are arranged on the side surface of the backing material 26 or embedded in the inside has been described, the pedestal 25 may be used instead of the backing material 26.

  In the above embodiment, the portable ultrasonic observation device 10 and the ultrasonic probe 11 are wired by the cable 20. However, the portable ultrasonic observation device such as the ultrasonic diagnostic apparatus 90 shown in FIG. 10 is used. You may apply to what transmits / receives the data between 91 and the ultrasonic probe 92 by radio | wireless.

  In FIG. 10, a portable ultrasonic observation device 91 and an ultrasonic probe 92 are provided with a wireless reception unit 93 and a wireless transmission unit 94 for wirelessly exchanging detection signals after A / D conversion, respectively. The ultrasonic probe 92 has a built-in battery 95, and power from the battery 95 is supplied to each part of the ultrasonic probe 92 via the power supply unit 96.

  According to the present invention, since a relatively high transmission / reception sensitivity can be obtained even if the UT is driven with a relatively low voltage, the voltage drop due to the transmission line is suppressed, so that the battery 95 is driven like the ultrasonic probe 92. The service life of the type can be made longer than before. In addition, since the circuit is driven at a low voltage, it is possible to reduce the circuit scale of the pulser and the like, and thus contribute to the miniaturization of the ultrasonic probe.

  As shown in FIG. 11, a multiplexer (hereinafter abbreviated as MUX) 100 that selectively switches the UT 27 to be driven may be interposed between the UT array 21, the pulser 46, and the receiver 50. For example, when the number of UTs 27 is 128 and the adjacent 48 UTs 27 are driven as one block by giving an arbitrary delay difference to each UT 27, the 48 units driven by the MUX 100 are selected. By doing so, it is only necessary to prepare the pulsar 46 and the receiver 50 for the number of UTs 27 to be driven at a time (in this case, 48), so that the ultrasonic probe can be further miniaturized.

  In the above embodiment, the first and second piezoelectric bodies 35 and 36 are made of piezoelectric ceramics made of the same material, and the areas of these transmission and reception surfaces are also the same, but a configuration like the UT 105 shown in FIG. In FIG. 12, the UT 105 includes a first piezoelectric body (hereinafter abbreviated as Ps) 106, a second piezoelectric body (hereinafter abbreviated as Ph) 107, and first, second, and third electrodes 108, 109, and 110. Is done.

Ps106 is a piezoelectric ceramic generally called a soft relaxor system, for example, Pb (Mn, Nb) O ₃ —PbTiO ₃ , Pb (Ni, Nb) O ₃ —PbTiO ₃ , Pb (Zn, Nb) O ₃ —PbTiO _3. Mainly _3rd . Unlike Ps106, Ph107 is a piezoelectric ceramic generally called a hard system, for example, a PZT (lead zirconate titanate) system. Both Ps106 and Ph107 are polarized in the same direction (from the bottom to the top indicated by the arrows).

  Ps106 and Ph107 are divided by a line parallel to the AZ direction. Ps106 has a longer length in the EL direction than Ph107, and therefore the area of the transmission / reception surface, which is the upper surface thereof, is larger than Ph107. The area ratio of the transmission / reception wave surface is, for example, Ps: Ph = 4: 1.

In this example, model number C-92H manufactured by Fuji Ceramics is used as Ps106, and model number C-5 manufactured by the company is used as Ph107. As shown in Table 2, the model number C-92H used for Ps106 has a relative dielectric constant ε ₃₃ of 5300, an equivalent piezoelectric constant d ₃₃ of 770, and a voltage output coefficient g ₃₃ of 16.4. On the other hand, the model number C-5 used for Ph107 has a relative dielectric constant ε ₃₃ of 1170, an equivalent piezoelectric constant d ₃₃ of 333, and a voltage output coefficient g ₃₃ of 32.1. Model number C-5 is about 0.43 times the equivalent piezoelectric constant _{d 33} is model number C-92H, the voltage output coefficient _{g 33} is approximately 1.95 times. The larger the equivalent piezoelectric constant d ₃₃ is, the higher the ultrasonic wave transmission capability is. The larger the voltage output coefficient g ₃₃ is, the higher the reflected wave reception sensitivity is. Therefore, Ps 106 has higher transmission capability than Ph 107, and Ph 107 has higher reception sensitivity than Ps 106. Can be said to be expensive.

  The first electrode 108 and the second electrode 109 are a lower electrode of Ps106 and an upper electrode of Ph107, respectively. The third electrode 110 serves as both the upper surface electrode of Ps106 and the lower surface electrode of Ph107. The 3rd electrode 110 has the connection part 111 bent in the substantially letter shape at the parting part of Ps106 and Ph107. The connecting portion 111 connects the upper electrode portion of Ps106 and the lower electrode portion of Ph107. Filling material 30 is filled in the outer surface of Ps106 and Ph107 and the part where Ps106 and Ph107 are separated, where connection portion 111 is located. The first electrode 108 and the second electrode 109 may be the upper electrode of Ps106 and the lower electrode of Ph107, respectively, and the third electrode 110 may serve as the lower electrode of Ps106 and the upper electrode of Ph107.

  First, second, and third switches (hereinafter referred to as SWa ′, SWb ′, and SWc ′) 112, 113, and 114 are connected to the first to third electrodes 108 to 110, respectively. SWa ′ 112 is a bifurcated switch, and connects the first electrode 108 and the pulser 46 or the ground in a selectable manner. SWb'113 and SWc'114 turn on / off the connection between the second electrode 109 and the receiving amplifier 47, and the third electrode 110 and the ground, respectively. The second electrode 109, SWb'113, and the reception amplifier 47 are directly connected to each other without using a capacitive transmission line, as in the above embodiment.

  As shown in Table 3, the selection states of SWa ′ to SWc ′ 112 to 114 are changed depending on whether an ultrasonic wave is transmitted or a reflected wave is received. When transmitting ultrasonic waves, SWa'112 is tilted toward the pulsar 46 side. Further, SWb'113 is turned off and SWc'114 is turned on. This is the same as the state shown in FIG. An equivalent circuit in this case is as shown in FIG. That is, the pulser 46 and the first electrode 108, and the third electrode 110 and the ground are connected. Then, an excitation pulse (driving voltage) from the pulser 46 is applied to Ps 106 sandwiched between the first electrode 108 and the third electrode 110, and ultrasonic waves (indicated by dotted arrows) are emitted from the upper surface of the Ps 106. Since SWb'113 is off, no excitation pulse is applied to Ph107 sandwiched between the second electrode 109 and the third electrode 110, and therefore no ultrasonic wave is emitted from Ph107.

  On the other hand, when receiving the reflected wave, SWa'112 is tilted to the ground side. Further, SWb'113 is turned on and SWc'114 is turned off. In the equivalent circuit in this case, as shown in FIG. 13B, the ground, the first electrode 108, the second electrode 109, and the reception amplifier 47 are connected. Ps 106 and Ph 107 are connected in series to the reception amplifier 47 by the electrodes 108 to 110. As in the above embodiment, the detection signal input to the reception amplifier 47 via the second electrode 109 and SWb ′ 113 is the sum of the detection signals output from Ps 106 and Ph 107.

  In Table 3, “active” indicates driving, and “inactive” indicates non-driving. When transmitting ultrasonic waves, ultrasonic waves are emitted only from Ps 106, so Ps 106 is “active” and Ph 107 is “inactive”. When a reflected wave is received, both the Ps 106 and Ph 107 receive the reflected wave and output a detection signal, so both are “active”.

  When transmitting ultrasonic waves, ultrasonic waves are emitted with Ps106 having relatively high transmission capability, and when receiving reflected waves, Ps106 and reflected waves are received with Ph107 having relatively high reception sensitivity. Therefore, the advantages of Ps106 and Ph107 are obtained. It can be said that this is a driving method that takes advantage of (compensates for disadvantages).

The ratio of the transmission and reception sensitivity (the area ratio of the transmitting surface) × {(reception sensitivity of Ps106) + (reception sensitivity of Ph107)} = (area ratio of the transmitting surface) × {1+ (of Ph107 for Ps106 voltage output coefficient _{g 33} )} = 0.80 × (1 + 1.95) = 2.36 (= + 7.46 dB). When the same kind of piezoelectric bodies are simply connected in series, the transmission / reception sensitivity is only several times that of the piezoelectric bodies, but in this example, the transmission / reception sensitivity is improved more than several times.

  Ps106 with relatively high transmission capability and Ph107 with relatively high reception sensitivity are connected in series with each electrode 108 to 110, and Ps106 is used when transmitting ultrasonic waves, and both Ps106 and Ph107 are detected when receiving reflected waves. Since the signal is output and the sum is input to the reception amplifier 47, the transmission / reception sensitivity can be further improved as compared with the prior art. If the transmission / reception sensitivity is improved, there is no need to increase the drive voltage applied to the UT 105, and low voltage drive is possible.

  When the number of piezoelectric bodies constituting the UT is n (n is a natural number of 2 or more), the shared electrodes such as the third electrode 110 that serve as one upper surface electrode and the other lower surface electrode of the adjacent piezoelectric body are n-1 are required. The total number of electrodes including the dual-purpose electrode is n + 1, and the number of electrodes other than the dual-purpose electrode is the first electrode 108 and the second electrode 109.

  The connection portion 111 is provided on the third electrode 110 which is a dual-purpose electrode which also serves as one upper surface electrode and the other lower surface electrode of the adjacent piezoelectric body. However, instead of the connection portion, one of the adjacent piezoelectric bodies is bonded by wire bonding or the like. The upper electrode and the other lower electrode may be made conductive. Further, a piezoelectric resin such as PVDF (polyvinylidene fluoride) may be used instead of the hard piezoelectric ceramic.

  In the above embodiment, the piezoelectric bodies are arranged along the EL direction, but may be arranged along the AZ direction. In the above embodiment, a so-called convex electronic scanning type extracorporeal ultrasonic probe has been exemplified. However, a radial electronic scanning type or a mechanical scanning scanning type ultrasonic probe that mechanically rotates, swings, or slides a single UT. An acoustic probe may be used. The present invention can also be applied to an in-vivo ultrasonic probe inserted into a forceps channel of an electronic endoscope or an ultrasonic endoscope integrated with an electronic endoscope.

2,90 Ultrasonic diagnostic apparatus 10, 91 Portable ultrasonic observation device 11, 92 Ultrasonic probe 21 Ultrasonic transducer array (UT array)
25 Pedestal 26 Backing material 27, 70, 75, 80, 105 Ultrasonic transducer (UT)
35 1st piezoelectric body 36 2nd piezoelectric body 37-40 1st-4th electrode 41-45 1st-5th switch (SWa-SWe)
46 Pulser 47 Receiving amplifier 51 A / D converter (A / D)
52 CPU
53 Scanning Control Unit 54 Beamformer (BF)
55 Detection Log Compression Circuit 71, 81 Flexible Printed Circuit Board (FPC)
85 Liquid refrigerant 86 Pipe line 94 Wireless transmitter 95 Battery 100 Multiplexer (MUX)
106 First piezoelectric body (Ps)
107 Second piezoelectric body (Ph)
108-110 1st-3rd electrode 111 Connection part 112-114 1st-3rd switch (SWa '-SWc')

Claims (20)

An ultrasonic transducer having a plurality of piezoelectric bodies arranged in a direction parallel to a transmission / reception surface of ultrasonic waves and reflected waves;
A changeover switch connected to each electrode sandwiching a plurality of piezoelectric bodies, and switching the connection of the plurality of piezoelectric bodies in parallel or in series,
Drive control means for operating the changeover switch so that a plurality of piezoelectric bodies are connected in parallel at the time of transmission of ultrasonic waves and connected in series at the time of reception of reflected waves;
An amplifier that receives a reflected wave and amplifies a detection voltage output from a piezoelectric body, and includes an amplifier that is directly connected without an electrode of a piezoelectric body and a capacitive transmission line. Acoustic probe. 2. The ultrasonic probe according to claim 1, wherein the amplifier is disposed on a side surface of the base material on which the piezoelectric body of the ultrasonic transducer is placed, which is perpendicular to the wave transmitting / receiving surface.   The ultrasonic probe according to claim 2, wherein the amplifier is mounted on a circuit board, and the circuit board is disposed on a side surface perpendicular to the wave transmitting / receiving surface of the base material.   The ultrasonic probe according to claim 3, wherein the changeover switch is mounted on the circuit board together with the amplifier.   5. The ultrasonic probe according to claim 1, wherein the amplifier is embedded in a base material on which a piezoelectric body of the ultrasonic transducer is placed.   The ultrasonic probe according to claim 5, wherein the amplifier is mounted on a circuit board, and the circuit board is embedded in a base material.   The ultrasonic probe according to claim 6, wherein the changeover switch is mounted on the circuit board together with the amplifier.   8. The ultrasonic probe according to claim 2, wherein a cooling mechanism for cooling the driving heat of the amplifier is provided on the base material.   The ultrasonic probe according to claim 1, wherein the amplifier is of a voltage feedback type or a charge storage type. The ultrasonic transducer has a plurality of piezoelectric bodies having different ultrasonic transmission capabilities and reflected wave reception sensitivity, and an electrode including a combined electrode that also serves as one upper surface electrode and the other lower surface electrode of an adjacent piezoelectric body, A plurality of piezoelectric bodies are connected in series by the electrodes,
The drive control means applies a drive voltage to electrodes other than one piezoelectric element via an electrode to generate an ultrasonic wave, receives a reflected wave, and detects a detection voltage output from the piezoelectric elements for all the piezoelectric elements. The ultrasonic probe according to claim 1, wherein the changeover switch is operated so as to be added by a minute amount.   The ultrasonic probe according to any one of claims 1 to 10, wherein the plurality of piezoelectric bodies are polarized in the same direction parallel to a normal line of a transmission / reception surface of ultrasonic waves and reflected waves. 12. The ultrasonic probe according to claim 10, wherein the plurality of piezoelectric bodies have different equivalent piezoelectric constants d ₃₃ , voltage output coefficients g ₃₃ , or area ratios of transmission and reception surfaces of ultrasonic waves and reflected waves. A first piezoelectric body at one end of the series connection;
A second piezoelectric body at the other end of the series connection, which has lower ultrasonic wave transmission capability and higher reflected wave reception sensitivity than the first piezoelectric body, and a lower area ratio of the transmission and reception surfaces of the ultrasonic wave and reflected wave;
A pulsar connected to an electrode that is not a dual-purpose electrode of the first piezoelectric body and supplying a driving voltage;
The amplifier is connected to an electrode that is not a dual-purpose electrode of the second piezoelectric body;
The changeover switch switches on / off the connection between the electrodes of the first piezoelectric body and the second piezoelectric body and the pulser and the amplifier,
The drive control means operates the changeover switch so that a drive voltage is applied to a piezoelectric body other than the second piezoelectric body, and a sum of detection signals from all the piezoelectric bodies is input to the amplifier. The ultrasonic probe according to any one of claims 10 to 12, characterized in that: The second piezoelectric body has an equivalent piezoelectric constant d ₃₃ lower than that of the first piezoelectric body, a high voltage output coefficient g ₃₃ , and a small area ratio of transmission and reception surfaces of ultrasonic waves and reflected waves. The ultrasonic probe according to any one of 10 to 13.   15. The ultrasonic probe according to claim 10, wherein the first piezoelectric body is a soft relaxor system, and the second piezoelectric body is a hard piezoelectric ceramic. The ultrasonic transducers are arranged in a plurality of arrays,
A pulser that supplies a drive voltage to the piezoelectric body;
Scanning control means for driving the pulser and scanning ultrasonic waves;
An A / D converter using the detection voltage amplified by the amplifier as a digital detection signal;
Signal processing means for executing signal processing for generating an ultrasound image from the detection signal;
The ultrasonic probe according to any one of claims 1 to 15, further comprising main control means for comprehensively controlling each part.   The ultrasonic probe according to claim 16, further comprising a multiplexer that selectively switches the ultrasonic transducer that transmits and receives ultrasonic waves and reflected waves. Power supply means for supplying power to each unit;
The ultrasonic probe according to claim 16, further comprising: a wireless transmission unit that wirelessly transmits a detection signal after signal processing to an ultrasonic observation device that displays an ultrasonic image. An ultrasonic transducer having a plurality of piezoelectric bodies arranged in a direction parallel to a transmission / reception surface of ultrasonic waves and reflected waves;
A changeover switch connected to each electrode sandwiching a plurality of piezoelectric bodies, and switching the connection of the plurality of piezoelectric bodies in parallel or in series,
Drive control means for operating the changeover switch so that a plurality of piezoelectric bodies are connected in parallel at the time of transmission of ultrasonic waves and connected in series at the time of reception of reflected waves;
An ultrasonic probe that receives a reflected wave and amplifies a detection voltage output from a piezoelectric body, and includes an amplifier directly connected to the piezoelectric body electrode without passing through a capacitive transmission line;
An ultrasonic diagnostic apparatus comprising: an ultrasonic observer connected to the ultrasonic probe and displaying an ultrasonic image. A piezoelectric body that transmits and receives ultrasonic waves and reflected waves;
A base on which the piezoelectric body is placed;
An ultrasonic transducer comprising an amplifier embedded in the base material and receiving a reflected wave and amplifying a detection voltage output from the piezoelectric body.

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