JP2011056103A - Ultrasonic probe and ultrasonic diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the transmission and reception sensitivities of an ultrasonic transducer by a lower voltage device. <P>SOLUTION: The ultrasonic transducer (UT) 27 includes a soft relaxer-based first piezoelectric body (Ps) 35, a hard-based second piezoelectric body (Ph) 36, first and second electrodes 37, 38, and a third electrode 39 serving also as the upper surface electrode of Ps 35 and the lower surface electrode Ph 36. The first electrode 37 is connected with a pulsar 44 via a first switch (SWa) 41, the second electrode 38 with a reception amplifier 45 via a second switch (SWb) 42, and the third electrode 39 with a gland via a third switch (SWc) 43, respectively. When the ultrasonic waves are transmitted, the pulsar 44 applies an exciting pulse only to the Ps 35. When the ultrasonic waves are received, the Ps 35 and Ph 36 are connected together in series, and the total of their detection signals are input to the reception amplifier 45. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  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. It is described that the voltage applied to the UT is increased in order to compensate for power shortage during transmission.

Japanese Patent Laid-Open No. 03-110998

  In Patent Document 1, the voltage applied to the UT is increased in order to compensate for power shortage during transmission of ultrasonic waves. Increasing the applied voltage increases the scale of the voltage application circuit (pulsar) and increases power consumption. In the type of ultrasonic probe having a built-in voltage application circuit, the size of the voltage application circuit increases and the size of the ultrasonic probe increases, and the operability most necessary for the ultrasonic probe is hindered. In particular, a wireless ultrasonic probe with a built-in voltage application circuit becomes larger in size when the applied voltage is increased, and further, because the battery is battery-driven, the service life is shortened and the usability is deteriorated.

  The present invention has been made in view of the above background, and an object of the present invention is to improve transmission / reception sensitivity of an ultrasonic transducer with lower voltage driving.

  The ultrasonic probe of the present invention is different in ultrasonic transmission capability and reflected wave reception sensitivity, and includes a plurality of piezoelectric bodies arranged in a direction parallel to the transmission / reception surface of ultrasonic waves and reflected waves, and one of adjacent piezoelectric bodies. And an ultrasonic transducer in which a plurality of piezoelectric bodies are connected in series by the electrode, and a drive voltage is applied to the other piezoelectric bodies via the electrodes. Drive control means for controlling the drive of the ultrasonic transducer so that the detection voltage output from the piezoelectric body by applying the ultrasonic wave by applying it and receiving the reflected wave is added for all the piezoelectric bodies. It is characterized by providing.

  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 normal direction 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 Connected to the second piezoelectric body at the other end of the first electrode, an electrode that is not the dual-purpose electrode of the first piezoelectric body, and connected to an electrode that is not the dual-purpose electrode of the second piezoelectric body It is preferable to include an amplifier that amplifies a voltage, and a changeover switch that switches on / off the connection between the electrodes of the first piezoelectric body and the second piezoelectric body, 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 amplifier and the electrode of the second piezoelectric body are directly connected without passing through a capacitive transmission line. The amplifier may be a voltage feedback type or a charge storage type.

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.

  The ultrasonic diagnostic apparatus of the present invention is different in ultrasonic transmission capability and reflected wave reception sensitivity, and includes a plurality of piezoelectric bodies arranged in a direction parallel to the transmission and reception surfaces of ultrasonic waves and reflected waves, and adjacent piezoelectric bodies. An ultrasonic transducer having an electrode including a dual-purpose electrode that also serves as one upper surface electrode and the other lower surface electrode, and a plurality of piezoelectric bodies connected in series by the electrode, and a drive voltage through the electrodes to other piezoelectric bodies A drive control means for controlling the drive of the ultrasonic transducer so that the ultrasonic wave is generated by applying and the reflected voltage is received and the detection voltage output from the piezoelectric body is added for all the piezoelectric bodies. It comprises an ultrasonic probe provided, and an ultrasonic observer connected to the ultrasonic probe and displaying an ultrasonic image.

  According to the present invention, an ultrasonic transducer having a plurality of piezoelectric bodies connected in series by an electrode including a dual-purpose electrode is different in ultrasonic wave transmission capability and reflected wave reception sensitivity. The drive voltage is applied to generate an ultrasonic wave, and the reflected voltage is received and the detection voltage output from the piezoelectric body is driven to be added for all the piezoelectric bodies. Can be 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 graph which shows the relationship between the synthetic capacitance ratio and area ratio of a 1st, 2nd piezoelectric material. 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 of another example. 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.

  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 44 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 (hereinafter abbreviated as Ps) 35, a second piezoelectric body (hereinafter abbreviated as Ph) 36, and first, second, and third electrodes 37, 38, and 39. (The pedestal 25, the acoustic matching layers 28a and 28b, and the acoustic lens 29 are not shown).

Ps35 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 Ps35, Ph36 is a piezoelectric ceramic generally called a hard system, for example, a PZT (lead zirconate titanate) system. Ps35 and Ph36 are both polarized in the same direction (from bottom to top as indicated by arrows).

  Ps35 and Ph36 are separated by a line parallel to the AZ direction. Ps35 has a length in the EL direction longer than Ph36, and therefore the area of the wave transmitting / receiving surface, which is the upper surface thereof, is larger than Ph36. 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 Ps35, and model number C-5 manufactured by the company is used as Ph36. As shown in Table 1, the model number C-92H used for Ps35 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 Ph36 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. As Equivalent piezoelectric constant _{d 33} is greater high ultrasound transmission capability, since the reception sensitivity enough reflected wave larger voltage output coefficient _{g 33} high, Ps35 has a high transmission capability than Ph36, Ph36 reception sensitivity than Ps35 Can be said to be expensive.

  The first electrode 37 and the second electrode 38 are a lower electrode of Ps35 and an upper electrode of Ph36, respectively. The third electrode 39 serves as both the upper surface electrode of Ps35 and the lower surface electrode of Ph36. The 3rd electrode 39 has the connection part 40 bent in the substantially letter shape at the parting part of Ps35 and Ph36. The connecting portion 40 connects the upper electrode portion of Ps35 and the lower electrode portion of Ph36. Filling material 30 is filled in the outer side surfaces of Ps35 and Ph36 and the part where Ps35 and Ph36 are separated, which has connecting portion 40. The first electrode 37 and the second electrode 38 may be the upper electrode of Ps35 and the lower electrode of Ph36, respectively, and the third electrode 39 may serve as the lower electrode of Ps35 and the upper electrode of Ph36.

  First, second, and third switches (hereinafter referred to as SWa, SWb, and SWc) 41, 42, and 43 are connected to the first to third electrodes 37 to 39, respectively. SWa41 is a bifurcated switch, and connects the first electrode 37 and the pulser 44 or ground in a selectable manner. SWb42 and SWc43 turn on / off the connection between the second electrode 38 and the voltage feedback or charge storage type receiving amplifier 45, and the third electrode 39 and the ground, respectively. The second electrode 38, the SWb 42, and the reception amplifier 45 are directly connected to each other without passing through the capacitive transmission line.

  As shown in Table 2, the selection states of SWa to SWc 41 to 43 change depending on whether the ultrasonic wave is transmitted or the reflected wave is received. When transmitting the ultrasonic wave, the SWa 41 is tilted to the pulsar 44 side. Also, SWb42 is off and SWc43 is 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 44 and the first electrode 37 and the third electrode 39 and the ground are connected. Then, an excitation pulse (driving voltage) from the pulser 44 is applied to Ps 35 sandwiched between the first electrode 37 and the third electrode 39, and ultrasonic waves (indicated by dotted arrows) are emitted from the upper surface of Ps 35. Since the SWb 42 is off, no excitation pulse is applied to the Ph 36 sandwiched between the second electrode 38 and the third electrode 39, and therefore no ultrasonic wave is emitted from the Ph 36.

  On the other hand, when receiving the reflected wave, SWa41 is tilted to the ground side. Further, SWb42 is turned on and SWc43 is turned off. In the equivalent circuit in this case, as shown in FIG. 4B, the ground, the first electrode 37, the second electrode 38, and the reception amplifier 45 are connected. Ps35 and Ph36 are connected in series to the reception amplifier 45 by the electrodes 37 to 39. When reflected waves (indicated by dotted arrows) are incident on the upper surfaces of Ps35 and Ph36, detection signals (detection voltages) corresponding thereto are output from Ps35 and Ph36. Since both Ps35 and Ph36 are polarized in the same direction indicated by the arrows, the detection signals do not cancel out with the same polarity. Since Ps35 and Ph36 are connected in series, the detection signal input to the reception amplifier 45 via the second electrode 38 and SWb42 is the sum of the detection signals output from Ps35 and Ph36.

  In Table 2, “active” indicates driving, and “inactive” indicates non-driving. When transmitting ultrasonic waves, ultrasonic waves are emitted only from Ps35, so Ps35 is “active” and Ph36 is “inactive”. When the reflected wave is received, both the Ps 35 and Ph 36 receive the reflected wave and output a detection signal, so both are “active”.

  When transmitting ultrasonic waves, ultrasonic waves are emitted with Ps35 having a relatively high transmission capability, and when receiving reflected waves, Ps35 and reflected waves are received with Ph36 having a relatively high receiving sensitivity. Therefore, the advantages of Ps35 and Ph36 are obtained. It can be said that this is a driving method that takes advantage of (compensates for disadvantages).

  When the model number C-92H manufactured by Fuji Ceramics is used as Ps35 and the model number C-5 manufactured by the company is used as Ph36, the combined capacitance when these are connected in series is the area ratio of the transmission / reception surface of Ps35 and Ph36. In response to this, it changes as shown in FIG. The vertical axis represents the ratio of the combined capacitance when the single Ps35 is 1, and the horizontal axis represents the area ratio of the Ps35 transmission / reception surface.

  For example, when the area ratio of the transmission / reception surface of Ps35 is 80% (the area ratio of the transmission / reception surface of Ph36 is 20%), the ratio of the combined capacitance can be read as 0.055 from the graph. The capacitance of the piezoelectric body used for the abdominal ultrasound probe is usually about 200 to 300 pF. The capacitance of the piezoelectric body of this example is reduced to about 200 to 300 × 0.055 = 11 to 16.5 pF. In this example, in order to suppress the influence of the voltage drop due to the decrease in capacitance as much as possible, the reception amplifier 45 is arranged in the immediate vicinity of the UT 27, and the second electrode 38, the SWb 42, and the reception amplifier 45 are directly connected to each other for transmission. The voltage drop due to the line is reduced.

The transmitting and receiving sensitivity, (area ratio of the transmitting surface) × {(Ps35 reception sensitivity) + (reception sensitivity of Ph36)} = voltage Ph36 for (area ratio of the transmitting surface) × {1+ (Ps35 output coefficient _{g 33} Ratio)} = 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.

  In FIG. 6, a receiver 50 is connected to the reception amplifier 45, 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 45. 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 44, and the reception amplifier 45 is shown here, but one receiver is provided for each UT 27, that is, the number of the UT 27 is provided. .

  The pulser 44 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 44 to be driven from the plurality of pulsars 44, 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 pulsar 44 transmits an excitation pulse for generating an ultrasonic wave in the UT 27 based on the drive signal transmitted from the scanning control unit 53.

  Further, the scanning control unit 53 controls the switching operation of the SWa to SWc 41 to 43.

  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 44 selected by the scanning control unit 53 to the UT 27, and the subject is irradiated with ultrasonic waves from the UT 27. The pulsar 44 driven by the scanning control unit 53 is sequentially switched for each transmission / reception of ultrasonic waves and reflected waves. Thereby, ultrasonic waves are scanned on the subject.

  At this time, the scanning control unit 53 causes the SWa 41 of the UT 27 that irradiates the ultrasonic wave to fall to the pulsar 44 side, the SWb 42 is turned off, and the SWc 43 is turned on. The excitation pulse from the pulsar 44 is applied to the Ps 35 via the first electrode 37 and the third electrode 39, and an ultrasonic wave is emitted from the Ps 35 toward the subject. Ultrasonic waves are not emitted from Ph36.

  The ultrasonic wave emitted from Ps35 is reflected by the subject, and a detection signal corresponding to the reflected wave is output from the UT27. At this time, the scanning control unit 53 causes the SWa 41 of the UT 27 that receives the reflected wave to fall to the ground side, the SWb 42 is turned on, and the SWc 43 is turned off. Ps 35 and Ph 36 are connected in series to the reception amplifier 45 by the electrodes 37 to 39. The reception amplifier 45 receives the sum of the detection signals output from Ps35 and Ph36.

  The detection signal from the UT 27 is amplified by the receiving amplifier 45, then 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, Ps35 having a relatively high transmission capability and Ph36 having a relatively high reception sensitivity are connected in series by the electrodes 37 to 39, Ps35 is used for transmitting ultrasonic waves, and Ps35 is used for receiving reflected waves. And Ph36 output the detection signal and input the sum to the reception amplifier 45, so that 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 27, and low voltage drive is possible.

  In the above embodiment, the UT 27 having two piezoelectric bodies of Ps35 and Ph36 is illustrated, but the number of piezoelectric bodies may be two or more. For example, as in a UT 70 shown in FIG. 7, another hard third piezoelectric body (hereinafter abbreviated as Ph ′) 71 may be added to the soft relaxer Ps 35 and the hard Ph 36. Similar to the above embodiment, Ps35, Ph36, and Ph'71 are polarized in the same direction. Further, the areas of the transmission and reception surfaces of Ph36 and Ph'71 are the same, and the area ratio of the transmission and reception surfaces is, for example, Ps: Ph: Ph '= 4: 1: 1.

  In this case, in addition to the third electrode 39 of the above-described embodiment, the fourth electrode 72 serving as the upper electrode of Ph36 and the lower electrode of Ph′71 and having the connection part 73 similar to the connection part 40 of the third electrode 39 is provided. Form. Further, the second electrode 38 of the above embodiment is the upper surface electrode of Ph′71. The connection between the first and second electrodes 37, 38 and the SWa41, SWb42 is the same as in the above embodiment. The point from which SWc43 is connected to the 4th electrode 72 instead of the 3rd electrode 39 differs from the said embodiment. The selection states of SWa to SWc 41 to 43 at the time of transmitting an ultrasonic wave and receiving a reflected wave are the same as those in Table 2.

When transmitting ultrasonic waves, ultrasonic waves are emitted from Ps35 and Ph36. It cannot be emitted from Ph'71. When receiving the reflected wave, Ps 35, Ph 36, and Ph ′ 71 are connected in series to the reception amplifier 45. As the number of piezoelectric bodies connected in series increases, the combined capacitance decreases, but the transmission / reception sensitivity improves. Since the third electrode 39 is the upper electrode of Ps35 and the lower electrode of Ph36, the ultrasonic waves emitted from Ps35 and Ph36 are in opposite phases, but the area of the transmission / reception surface of Ph36 is smaller than that of Ps35. , the equivalent piezoelectric constant _{d 33} also is smaller Ph36, cancellation of ultrasound Ps35 by ultrasound Ph36 is slight.

  When the number of piezoelectric bodies constituting the UT is n (n is a natural number of 2 or more), the third electrode 39 and the fourth electrode 72 that also serve as one upper surface electrode and the other lower surface electrode of adjacent piezoelectric bodies. N-1 common electrodes 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 37 and the second electrode 38.

  In the above-described embodiment, an example in which the portable ultrasonic observation device 10 and the ultrasonic probe 11 are wire-connected by the cable 20 has been described. However, a portable ultrasonic observation device such as the ultrasonic diagnostic apparatus 80 illustrated in FIG. You may apply to what transmits / receives the data between 81 and the ultrasonic probe 82 by radio | wireless.

  In FIG. 8, a portable ultrasonic observation device 81 and an ultrasonic probe 82 are provided with a wireless reception unit 83 and a wireless transmission unit 84 for wirelessly exchanging detection signals after A / D conversion. The ultrasonic probe 82 has a built-in battery 85, and power from the battery 85 is supplied to each part of the ultrasonic probe 82 via the power supply unit 86.

  According to the present invention, even when the UT is driven at a relatively low voltage, a relatively high transmission / reception sensitivity can be obtained. Therefore, the service life of the type driven by the battery 85, such as the ultrasonic probe 82, can be made longer than before. be able to. 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. 9, a multiplexer (hereinafter abbreviated as MUX) 90 that selectively switches the UT 27 to be driven may be interposed between the UT array 21, the pulser 44, 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 90 are selected. In this way, since the pulsar 44 and the receiver 50 need only be prepared for the number of UTs 27 to be driven at a time (48 in this case), the ultrasonic probe can be further miniaturized.

  In the above-described embodiment, the connection portions 40 and 73 are provided on the third electrode 39 and the fourth electrode 72, which are dual-purpose electrodes that also serve as one upper surface electrode and the other lower surface electrode of adjacent piezoelectric bodies. One upper surface electrode and the other lower surface electrode of adjacent piezoelectric bodies may be made conductive by wire bonding or the like.

  In the above embodiment, the piezoelectric bodies are arranged along the EL direction, but may be arranged along the AZ direction. Further, a piezoelectric resin such as PVDF (polyvinylidene fluoride) may be used instead of the hard piezoelectric ceramic.

  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, 80 Ultrasonic diagnostic apparatus 10, 81 Portable ultrasonic observation device 11, 82 Ultrasonic probe 21 Ultrasonic transducer array (UT array)
27, 70 Ultrasonic transducer (UT)
35 First piezoelectric body (Ps)
36 Second piezoelectric body (Ph)
37-39 1st-3rd electrode 40,73 Connection part 41-43 1st-3rd switch (SWa-SWc)
44 Pulser 45 Receiving amplifier 51 A / D converter (A / D)
52 CPU
53 Scanning Control Unit 54 Beamformer (BF)
55 Detection Log Compression Circuit 71 Third Piezoelectric Body (Ph ′)
72 4th electrode 84 Wireless transmission part 85 Battery 90 Multiplexer (MUX)

Claims (12)

A plurality of piezoelectric bodies arranged in a direction parallel to the transmission / reception surface of the ultrasonic waves and the reflected waves, and one upper surface electrode and the other lower surface electrode of the adjacent piezoelectric bodies having different ultrasonic transmission capabilities and reflected wave reception sensitivities An ultrasonic transducer in which a plurality of piezoelectric bodies are connected in series by the electrode,
A drive voltage is applied to electrodes other than one through an electrode to generate an ultrasonic wave, and a detection voltage output from the piezoelectric body by receiving a reflected wave is added for all the piezoelectric bodies. An ultrasonic probe comprising drive control means for controlling the drive of the ultrasonic transducer.   The ultrasonic probe according to claim 1, wherein the plurality of piezoelectric bodies are polarized in a normal direction of a transmission / reception surface of ultrasonic waves and reflected waves. 3. The ultrasonic probe according to claim 1, 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 pulser that is connected to an electrode that is not a dual-purpose electrode of the first piezoelectric body and supplies a driving voltage;
An amplifier that is connected to an electrode that is not a dual-purpose electrode of the second piezoelectric body and amplifies a detection voltage;
A switch for switching on / off the connection of the first piezoelectric body, the electrode of the second piezoelectric body, and the connection between 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 1 to 3, wherein   5. The ultrasonic probe according to claim 4, wherein the amplifier and the electrode of the second piezoelectric body are directly connected without using a capacitive transmission line. 6.   The ultrasonic probe according to claim 4, wherein the amplifier is of a voltage feedback type or a charge storage type. 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 4 to 6.   The ultrasonic probe according to any one of claims 4 to 7, 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 claim 1, further comprising main control means for comprehensively controlling each unit.   The ultrasonic probe according to claim 9, 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 9, 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. A plurality of piezoelectric bodies arranged in a direction parallel to the transmission / reception surface of the ultrasonic waves and the reflected waves, and one upper surface electrode and the other lower surface electrode of the adjacent piezoelectric bodies having different ultrasonic transmission capabilities and reflected wave reception sensitivities An ultrasonic transducer in which a plurality of piezoelectric bodies are connected in series by the electrode, and a drive voltage is applied to the other piezoelectric bodies via the electrodes to generate ultrasonic waves. And an ultrasonic probe comprising drive control means for controlling the drive of the ultrasonic transducer so that the detection voltage output from the piezoelectric body upon receiving the reflected wave is added for all of the piezoelectric bodies;
An ultrasonic diagnostic apparatus comprising: an ultrasonic observer connected to the ultrasonic probe and displaying an ultrasonic image.

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