Ultrasonic transducer drive device and ultrasonic probe

Abstract

The purpose of this disclosure is to suppress noise generated by an ultrasonic transducer drive device in which a transmit / receive separation switch is provided between the output terminal of the transmitter and the input terminal of the receiver. [Solution] The transmitting / receiving circuit 10 includes a first transmitter TXH that outputs a first transmission signal to an ultrasonic transducer 14, a second transmitter TXL that outputs a second transmission signal with a smaller amplitude than the first transmission signal to the ultrasonic transducer, a receiver RX that receives the received signal output from the ultrasonic transducer 14, a transmit / receive separation switch 18, and a drive circuit 20. The drive circuit 20 turns off the transmit / receive separation switch 18 when the first transmitter TXH outputs a first transmission signal, turns on the transmit / receive separation switch 18 when the second transmitter TXL outputs a second transmission signal based on control by a control circuit 16 provided separately from the drive circuit 20, and turns on the transmit / receive separation switch 18 independently of the control by the control circuit 16 when a received signal is input to the receiver RX.

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic transducer driving device and an ultrasonic probe, and particularly to a device that outputs a transmission signal to an ultrasonic transducer and receives a reception signal output from the ultrasonic transducer.

Background Art

[0002] Ultrasonic diagnostic devices that observe the tissues of a subject by transmitting and receiving ultrasonic waves are widely used. In an ultrasonic diagnostic device, an ultrasonic pulse is transmitted from an ultrasonic probe, and a reflected wave based on the ultrasonic pulse is received by the ultrasonic probe. The output terminal of a transmitter for transmitting an ultrasonic pulse and the input terminal of a receiver for receiving the reflected wave are connected to an ultrasonic transducer included in the ultrasonic probe.

[0003] Generally, the amplitude of the pulse signal output by the transmitter is larger than the amplitude of the signal input to the receiver. When designing a circuit with an appropriate withstand voltage according to the amplitude of the signal for each of the transmitter and the receiver, the receiver may be difficult to withstand the voltage of the transmission pulse.

[0004] Therefore, as shown in Patent Document 1, it is conceivable to provide a transmission / reception separation switch (high-voltage switch) between the input terminal of the receiver and the output terminal of the transmitter. When transmitting an ultrasonic pulse, the transmission / reception separation switch is turned off, and when receiving a reflected ultrasonic wave, the transmission / reception separation switch is turned on. This avoids the transmission pulse output from the transmitter from applying an electrical stress to the receiver. Note that Non-Patent Document 1 describes a switch for separating the transmission circuit and the reception circuit of an ultrasonic diagnostic device and a gate driver for controlling the switch as circuits related to the present disclosure.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] [Non-Patent Document 1] B. Dufort, T. Letavic and S. Mukherjee, “Digitally Controlled High-Voltage Analog Switch Array for Medical Ultrasound Applications in Thin-Layer Silicon-On-Insulator Process”, 2002 IEEE International SO1 Conference, 10 / 02,p78-p79. [Overview of the project] [Problems that the invention aims to solve]

[0007] In the transmit / receive isolation switches described in Patent Document 1 and Non-Patent Document 1, noise may be generated in the gate driver that controls the transmit / receive isolation switch, causing noise to be introduced into the current flowing through the main line path of the transmit / receive isolation switch. This can increase the noise in the signal output from the ultrasound probe and the signal transmitted within the ultrasound diagnostic device.

[0008] The purpose of this disclosure is to suppress noise generated by an ultrasonic transducer drive device in which a transmit / receive separation switch is provided between the output terminal of the transmitter and the input terminal of the receiver. [Means for solving the problem]

[0009] This disclosure provides an ultrasonic transducer driving device provided for each of a plurality of ultrasonic transducers, comprising: a first transmitter that outputs a first transmission signal to the ultrasonic transducer; a second transmitter that outputs a second transmission signal to the ultrasonic transducer having a smaller amplitude than the first transmission signal; a receiver that receives a received signal output from the ultrasonic transducer; a transmit / receive separation switch; and a driving circuit that controls the transmit / receive separation switch, wherein the first end of the transmit / receive separation switch is connected to the ultrasonic transducer and the output end of the first transmitter; the second end of the transmit / receive separation switch is connected to the output end of the second transmitter and the input end of the receiver; the driving circuit turns off the transmit / receive separation switch when the first transmitter outputs the first transmission signal; turns on the transmit / receive separation switch based on control by a control circuit provided separately from the driving circuit and common to the plurality of ultrasonic transducers when the second transmitter outputs the second transmission signal; and turns on the transmit / receive separation switch independently of control by the control circuit when the received signal is input to the receiver.

[0010] In one embodiment, the drive circuit turns on the transmit / receive separation switch by a control current that depends on the current flowing through the control circuit when the second transmitter outputs the second transmit signal, and turns on the transmit / receive separation switch by an autocurrent independent of the current flowing through the control circuit when the receiver receives the receive signal.

[0011] In one embodiment, the transmit / receive separation switch comprises two switching elements, each of which includes a first electrode, a second electrode, and a control electrode, and switches the connection between the first electrode and the second electrode on and off depending on the voltage between the control electrode and the second electrode, the second electrode and the control electrode of the two switching elements are connected in common, the first electrode of one of the two switching elements is the first end and the first electrode of the other is the second end, and the transmit / receive separation switch further comprises a constant voltage device connected between the control electrode and the second electrode of each switching element, and the drive circuit flows the control current through the constant voltage device when the second transmitter outputs the second transmit signal, and flows the self current through the constant voltage device when the receiver receives the receive signal.

[0012] In one embodiment, the drive circuit includes a drive switching element and a communication switch provided between the drive switching element and a control switching element of the control circuit, wherein the communication switch is turned on when the second transmitter outputs the second transmission signal and turned off when the receiver receives the reception signal, and when the communication switch is turned on, the drive switching element together with the control switching element constitutes a current mirror circuit.

[0013] In one embodiment, the input terminal of the receiver is connected to the second terminal of the transmit / receive separation switch via a receive input circuit, the receive input circuit includes a receive switch provided between the second terminal of the transmit / receive separation switch and the receiver, the receive switch turns on when the receive signal is input to the receiver and turns off when the second transmitter outputs the second transmit signal.

[0014] In one embodiment, a limiter is provided between the receiving switch and the receiver, the limiter defining the maximum potential fluctuation in the path between the receiving input circuit and the receiver.

[0015] An ultrasonic probe according to one embodiment includes the plurality of ultrasonic transducers, the ultrasonic transducer driving devices provided corresponding to the respective ultrasonic transducers, and the control circuit.

Advantages of the Invention

[0016] According to the present disclosure, noise generated by the ultrasonic transducer driving device can be suppressed.

Brief Description of the Drawings

[0017] [Figure 1] It is a diagram showing the configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present disclosure. [Figure 2] It is a diagram showing a configuration example of a transmission / reception circuit. [Figure 3] It is a control timing chart of the transmission / reception circuit. [Figure 4] It is a diagram showing the configuration of an ultrasonic diagnostic apparatus according to an application embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0018] Embodiments of the present disclosure will be described with reference to the respective drawings. The same components shown in the plurality of drawings are denoted by the same reference numerals to simplify the description. Terms such as "input end", "output end", "first end", "second end", etc. with "end" appended at the end in the present specification mean connection parts of circuit elements shown in a circuit diagram, and do not necessarily mean only the tips of conducting wires or connection terminals. The ends as connection parts in circuit elements may be formed of various forms of conductive substances such as conducting wires, conductor plates, and three-dimensional conductors in circuit elements.

[0019] FIG. 1 shows the configuration of an ultrasonic diagnostic apparatus 100 according to an embodiment of the present disclosure. The ultrasonic diagnostic apparatus 100 includes an ultrasonic probe 102 and a main body device 104. The ultrasonic probe 102 includes a plurality of ultrasonic transducers 14, a plurality of sub-arrays 12, a plurality of adders 22, and a control circuit 16.

[0020] The plurality of ultrasonic transducers 14 in the present embodiment are two-dimensionally arranged. The two-dimensional arrangement refers to an arrangement form in which a plurality of ultrasonic transducers 14 are arranged in each of two orthogonal directions. In addition to the two-dimensional arrangement, other arrangement forms such as a one-dimensional arrangement may be adopted. Also, a plurality of ultrasonic transducers 14 may be arranged according to forms such as a linear probe, a convex probe, a sector probe, etc.

[0021] The subarray 12 has a plurality of transceiver circuits 10. One ultrasonic transducer 14 is connected to each of the plurality of transceiver circuits 10 included in the subarray 12. Each ultrasonic transducer 14 is connected to the corresponding transceiver circuit 10 among the plurality of transceiver circuits 10 provided by the plurality of subarrays 12. The transceiver circuit 10 has a function as an ultrasonic transducer driving device that outputs a transmission signal to the ultrasonic transducer 14 and receives an input of a reception signal output from the ultrasonic transducer 14. The transceiver circuit 10 having a function as an acoustic wave transducer driving device is provided for each of the plurality of ultrasonic transducers 14.

[0022] A plurality of reception signals are output from the plurality of transceiver circuits 10 included in one subarray 12 to one adder 22. The adder 22 adds the plurality of reception signals to generate a composite signal and outputs it to the main body device 104. The main body device 104 includes an analog front-end circuit FE corresponding to each of the plurality of adders 22. The composite signal output from each adder 22 is input to the analog front-end circuit FE corresponding to each adder 22. Based on the composite signal subjected to processing such as amplification by each analog front-end circuit FE, the main body device 104 generates, for example, image data representing an image such as a B-mode image, a color Doppler image, an image showing a continuous wave Doppler waveform, etc.

[0023] The transmit / receive circuit 10 will now be described. The transmit / receive circuit 10 comprises a first transmitter TXH, a transmit / receive decoupling switch 18, a drive circuit 20, a second transmitter TXL, a receiver RX, and a delay unit DL. The output terminal of the first transmitter TXH and the first terminal of the transmit / receive decoupling switch 18 are connected to one end of an ultrasonic transducer 14. The other end of the ultrasonic transducer 14 is connected to a ground conductor. The second terminal of the transmit / receive decoupling switch 18 is connected to the input terminal of the receiver RX and the output terminal of the second transmitter TXL. The output terminal of the receiver RX is connected to the input terminal of the delay unit DL, and the output terminal of the delay unit DL is connected to the input terminal of an adder 22. The drive circuit 20 is controlled by a controller 24 provided in the main unit 104. The drive circuit 20 controls the transmit / receive decoupling switch 18 to be on or off according to the control of the controller 24.

[0024] The ultrasonic probe 102 and the main unit 104 are connected by multiple cable conductors 26 that constitute a cable. The adder 22 and the analog front-end circuit FE, and the controller 24 and each transmit / receive circuit 10 are also connected by cable conductors 26.

[0025] The transmitting and receiving circuit 10 is controlled by the controller 24 to one of the following states: pulse transmission state, reception state, or continuous wave transmission state. Here, the pulse transmission state refers to the state in which the first transmitter TXH outputs a pulse signal (first transmission signal) to the ultrasonic transducer 14. A pulse signal is a signal whose value changes pulsatically over time. When the state of the transmitting and receiving circuit 10 is set to the pulse transmission state, the drive circuit 20 controls the transmit / receive separation switch 18 to the OFF state. When the pulse signal is output from the first transmitter TXH to the ultrasonic transducer 14, the ultrasonic transducer 14 outputs ultrasonic pulses.

[0026] The receiving state refers to the state in which the received signal output by the ultrasonic transducer 14 based on the ultrasonic waves that have arrived at the ultrasonic transducer 14 is input to the receiver RX via the transmit / receive separation switch 18. When the state of the transmit / receive circuit 10 is set to the receiving state, the drive circuit 20 controls the transmit / receive separation switch 18 to the ON state.

[0027] The continuous wave transmission state refers to the state in which the second transmitter TXL outputs a continuous wave signal (second transmission signal) to the ultrasonic transducer 14 via the transmit / receive separation switch 18. Here, a continuous wave signal refers to a signal whose value changes periodically over time. The continuous wave signal is a signal for operating the ultrasound diagnostic device 100 in continuous wave Doppler mode, and the waveform of the signal does not need to have mathematically strictly defined continuity. That is, the continuous wave signal only needs to have a waveform such that continuous wave ultrasound is output from the ultrasonic transducer 14 by the continuous wave signal, and the Doppler shift frequency of the reflected ultrasound generated by the reflection of the continuous wave ultrasound within the subject can be detected.

[0028] When the state of the transmitting / receiving circuit 10 is set to a continuous wave state, the drive circuit 20 controls the transmit / receive separation switch 18 to turn ON. When a continuous wave signal is output from the second transmitter TXL to the ultrasonic transducer 14, the ultrasonic transducer 14 outputs continuous ultrasound.

[0029] When the ultrasound diagnostic device 100 operates in continuous wave Doppler mode, some of the transmit / receive circuits 10 belonging to the multiple sub-arrays 12 enter a continuous wave transmission state. The remaining transmit / receive circuits 10 belonging to the other part of the multiple sub-arrays 12 enter a receive state. Continuous wave ultrasound is output from the ultrasonic transducer 14 connected to the transmit / receive circuits 10 in the continuous wave transmission state. The reflected ultrasound generated by the reflection of the continuous wave ultrasound within the subject is received by the ultrasonic transducer 14 connected to the transmit / receive circuits 10 in the receive state. The ultrasonic transducer 14 outputs a received signal as an electrical signal corresponding to the received reflected ultrasound to the receiver RX via the transmit / receive separation switch 18.

[0030] The receiver RX amplifies the received signal and outputs it to the delay unit DL. The delay unit DL delays the received signal so that a received beam is formed, according to the control of the controller 24, and outputs it to the adder 22. That is, the delay unit DL corresponding to each of the multiple transmitting and receiving circuits 10 that make up one subarray 12 delays the received signal so that the received signals output from each transmitting and receiving circuit 10 reinforce each other based on ultrasound arriving from a specific receiving beam direction. The adder 22 adds the received signals output from each transmitting and receiving circuit 10 to generate a composite signal and outputs it to the main unit 104. In this way, the delay units DL in the multiple transmitting and receiving circuits 10 that make up the subarray 12 and the adder 22 corresponding to the subarray 12 constitute a phase-correcting adder. The main unit 104 generates data representing blood flow velocity, etc., based on the composite signal obtained by phase-correcting addition.

[0031] When the ultrasound diagnostic device 100 operates in pulse measurement mode, which is a mode other than continuous wave Doppler mode, each transmit / receive circuit 10 alternately switches between pulse transmission and reception states over time. Here, pulse measurement modes include B-mode and color Doppler mode. In pulse measurement mode, ultrasonic pulses are output from the ultrasonic transducers 14 connected to each transmit / receive circuit 10 in pulse transmission mode. The ultrasonic transducers 14 connected to each transmit / receive circuit 10 in reception mode receive the reflected ultrasonic waves generated when the ultrasonic pulses are reflected within the subject. Based on the composite signal generated by phase addition of the received signals output from each transmit / receive circuit 10 in reception mode, the main unit 104 generates image data representing an image corresponding to the operating mode, such as a B-mode image or a color Doppler image.

[0032] The first transmitter TXH, the receiver RX, and the second transmitter TXL are designed according to the amplitude of the signal being transmitted. The use of circuit elements with appropriate voltage ratings ensures that these devices are of appropriate size. Furthermore, their nonlinear characteristics and noise characteristics are optimized.

[0033] In this embodiment, the amplitude of the voltage of the pulse signal output by the first transmitter TXH is greater than the amplitude of the voltage of the received signal input to the receiver RX. Furthermore, the amplitude of the pulse signal output by the first transmitter TXH is greater than the amplitude of the voltage of the continuous wave signal output by the second transmitter TXL.

[0034] If the first transmitter TXH, receiver RX, and second transmitter TXL are each designed with appropriate voltage ratings according to the amplitude of the transmitted signal, the voltage ratings of the receiver RX and second transmitter TXL may not be able to withstand the pulse signal output by the first transmitter TXH.

[0035] Therefore, in the transmit / receive circuit 10 according to this embodiment, the transmit / receive separation switch 18 is turned off when the pulse transmission state is active. As a result, when the first transmitter TXH outputs a pulse signal, the receiver RX and the second transmitter TXL are electrically disconnected from the first transmitter TXH, and the application of a voltage based on the pulse signal to the receiver RX and the second transmitter TXL is avoided.

[0036] In this embodiment, the state in which the transmit / receive separation switch 18 is turned on during continuous wave transmission is different from the state in which the transmit / receive separation switch 18 is turned on during reception. This is to appropriately control the range of voltage that can be taken at the second end of the transmit / receive separation switch 18 (one end on the receiver RX and second transmitter TXL side), or to appropriately control the noise input from the drive circuit 20 to the receiver RX via the transmit / receive separation switch 18. In the following description, the state in which the transmit / receive separation switch 18 is turned on during continuous wave transmission is referred to as the continuous transmit ON state, and the state in which the transmit / receive separation switch 18 is turned on during reception is referred to as the receive ON state.

[0037] In the continuous transmission ON state, the current flowing from the drive circuit 20 to the transmit / receive separation switch 18, and further flowing into the main line path connecting the first and second ends within the transmit / receive separation switch 18, is controlled according to the operation of the control circuit 16, which is provided in common for multiple transmit / receive circuits 10, and the operation of the drive circuit 20. That is, the current flowing from the drive circuit 20 to the transmit / receive separation switch 18, and further flowing into the main line path of the transmit / receive separation switch 18, is a control current that depends on the current flowing through the control circuit 16. The control current is a current that is controlled by the control circuit 16 to be constant or to have its fluctuations suppressed. As a result, the input impedance of the second end of the transmit / receive separation switch 18 becomes an appropriate value, and the range of possible voltages at the second end of the transmit / receive separation switch 18 becomes sufficient for the amplitude of the continuous wave signal.

[0038] Next, in the receive-on state, the connection between the drive circuit 20 and the control circuit 16 is disconnected internally. In the receive-on state, the current flowing from the drive circuit 20 to the transmit / receive separation switch 18, and further flowing into the main line path within the transmit / receive separation switch 18, is controlled according to the operation of the drive circuit 20, not by the control circuit 16. In other words, the current flowing from the drive circuit 20 to the transmit / receive separation switch 18, and further flowing into the main line path of the transmit / receive separation switch 18, is an independent self-current separate from the current flowing to the control circuit 16. As a result, the noise input to the receiver RX from the drive circuit 20 via the transmit / receive separation switch 18 is independent of the operation of the control circuit 16.

[0039] In the ultrasonic probe 102 according to this embodiment, miniaturization is achieved by providing a common control circuit 16 for multiple transmitting and receiving circuits 10, that is, for multiple ultrasonic transducers 14. If the current flowing from the drive circuit 20 to the main path of the transmit / receive separation switch 18 is controlled according to both the control circuit 16 and the drive circuit 20, the noise generated by the control circuit 16 is commonly correlated among the outputs of all transmitting and receiving circuits 10 included in the subarray 12. Therefore, the composite signal based on multiple received signals output from the subarray 12 includes noise superimposed from highly correlated noise output from multiple transmitting and receiving circuits 10. If the subarray 12 contains N transmitting and receiving circuits 10, theoretically, the composite signal will include noise with N times the power of the noise generated by the control circuit 16 from the noise output from one transmitting and receiving circuit 10.

[0040] Therefore, in the ultrasonic probe 102 according to this embodiment, the current flowing from the drive circuit 20 to the main line path of the transmit / receive separation switch 18 is controlled according to the operation of the drive circuit 20, without depending on the control circuit 16. The composite signal based on multiple received signals output from the subarray 12 contains noise superimposed with uncorrelated noise. If the subarray 12 contains N transmit / receive circuits 10, theoretically the composite signal contains noise with power not N times, but √N times, compared to the noise output from one transmit / receive circuit 10. Therefore, depending on the receive ON state, the noise contained in the composite signal generated by each subarray 12 is suppressed.

[0041] Figure 2 shows an example configuration of the transmit / receive circuit 10. The transmit / receive isolation switch 18 includes MOSFETm1 and MOSFETm2 as two switching elements. The transmit / receive isolation switch 18 also includes a Zener diode D1 as a constant voltage device. Here, a switching element includes a first electrode, a second electrode, and a control electrode, and is an element in which the connection between the first electrode and the second electrode is switched on or off depending on the voltage between the control electrode and the second electrode. In a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), the gate corresponds to the control electrode, and the drain and source correspond to the first electrode and the second electrode, respectively. Other electrical circuit elements or circuits that maintain a constant voltage between terminals may be used as a constant voltage device instead of the Zener diode D1.

[0042] The sources of MOSFETm1 and MOSFETm2 are connected in common. The gates of MOSFETm1 and MOSFETm2 are also connected in common. The cathodes of Zener diode D1 are connected to the gates of MOSFETm1 and m2, and the anodes of Zener diode D1 are connected to the sources of MOSFETm1 and m2. The drain of MOSFETm1 is the first terminal of the transmit / receive isolation switch 18, and the drain of MOSFETm2 is the second terminal of the transmit / receive isolation switch 18.

[0043] The drive circuit 20 includes a logic buffer BUF, MOSFETs m3, m4, and m5. The logic buffer BUF is connected to the positive power line LV+ and the ground conductor. The output terminal of the logic buffer BUF is connected to the source of MOSFET m3. The drain of MOSFET m3 is connected to the gates of MOSFET m1 and m2 and the cathode of Zener diode D1. The drain of MOSFET m4 is connected to the gate of MOSFET m3. The source of MOSFET m4 is connected to the ground conductor. The source of MOSFET m5 is connected to the gate of MOSFET m3 and the drain of MOSFET m4. The drain of MOSFET m5 is connected to the gate of MOSFET m0.

[0044] The controller 24 inputs the control signal CWbar to the gates of MOSFETs m4 and m5, respectively. When the control signal CWbar is high voltage, MOSFET m4 turns on and MOSFET m5 turns off. When the control signal CWbar is low voltage, MOSFET m4 turns off and MOSFET m5 turns on.

[0045] A control signal SW is input from the controller 24 to the input terminal of the logic buffer BUF. When the control signal SW is high voltage, the voltage at the output terminal of the logic buffer BUF becomes LV+, and when the control signal SW is low voltage, the voltage at the output terminal of the logic buffer BUF becomes 0.

[0046] The control circuit 16 includes a MOSFETm0 and a constant current source I1. The source of MOSFETm0 is connected to the positive power line LV+, and its drain is connected to the positive terminal of the constant current source I1. The negative terminal of the constant current source I1 is connected to the ground conductor. The gate of MOSFETm0 is connected to its own drain, as well as to the drain of MOSFETm5 in the drive circuit 20 provided in each transmit / receive circuit 10.

[0047] Thus, the drive circuit 20 includes a MOSFETm3 as a drive switching element and a MOSFETm5 as a communication switch. MOSFETm5 is positioned between the gate of MOSFETm3 and the gate of MOSFETm0, which is a control switching element. As will be described later, MOSFETm5 turns on when the second transmitter TXL outputs a continuous wave signal and turns off when a received signal is input to the receiver RX. When MOSFETm5 is turned on, MOSFETm3, together with MOSFETm0, forms a current mirror circuit.

[0048] The first transmitter TXH is connected to the positive power line HV+ and the negative power line HV-. The second transmitter TXL is connected to the positive power line LV+ and the negative power line LV-. The receiver RX and the delay unit DL are each connected to the positive power line LV+ and the ground conductor.

[0049] The above example shows the use of a MOSFET as a switching element. Other switching elements such as a JFET (Junction Field Effect Transistor) or a bipolar transistor may be used instead of a MOSFET. When a bipolar transistor is used, the base is connected to the point where the gate of the MOSFET is connected, and the collector and emitter are connected to the points where the drain and source of the MOSFET are connected, respectively.

[0050] The specific operation of the transmit / receive circuit 10 shown in Figure 2 will be explained with reference to the control timing chart shown in Figure 3. Charts (a) to (e) in Figure 3 show the time waveforms of the control signal SW, control signal CWbar, oscillator voltage, transmit / receive separation switch gate / source potential, and m2 drain potential for the pulse transmission state, receive state, and continuous wave transmission state, respectively.

[0051] In the following explanation, the term "potential" refers to a voltage relative to the potential of the ground conductor. Furthermore, the symbols "HV+" and "LV+" used above to indicate the positive power line are also used to indicate potential. Similarly, the symbols "HV-" and "LV-" used to indicate the negative power line are also used to indicate potential.

[0052] The control signals SW and CWbar represent voltage values ​​relative to the ground potential of each control signal. The transducer voltage represents the potential at one end of the ungrounded ultrasonic transducer 14. The transmit / receive separation switch gate / source potentials represent the gate potentials and source potentials of MOSFETs m1 and m2. The solid time waveform represents the source potential, and the dashed time waveform represents the gate potential. The m2 drain potential represents the drain potential of MOSFET m2.

[0053] The pulse transmission state is described below. As shown in charts (a) and (b), in the pulse transmission state, the control signal SW is at a low potential of 0, and the control signal CWbar is at a high potential of LV+. Therefore, MOSFETm4 is on, MOSFETm5 is off, and MOSFETm3 is off. As a result, the terminal voltage of Zener diode D1 becomes 0, and the voltage between the gate and source of MOSFETm1 and m2 becomes 0, turning MOSFETm1 and m2 off.

[0054] As shown in chart (c), the oscillator voltage fluctuates in a pulsed manner within the range from a minimum value HV- to a maximum value HV+. Since MOSFETs m1 and m2 are off, as shown in chart (d), when the oscillator voltage is positive or 0, the gate potential and source potential of MOSFETs m1 and m2 are 0. Therefore, there is no conduction between the first and second ends of the transmit / receive separation switch 18.

[0055] When the oscillator voltage is negative, the parasitic diode in MOSFETm1 becomes forward-biased. As a result, as shown in chart (d), the gate and source potentials of MOSFETm1 and m2 become the same as the oscillator voltage (negative) and drop to the minimum value HV-. However, because the parasitic diode of MOSFETm2 becomes reverse-biased, there is no conduction between the first and second terminals of the transmit / receive separation switch 18.

[0056] Therefore, as shown in chart (e), when the first transmitter TXH outputs a pulse signal, the potential of the drain of MOSFETm2, i.e., the second terminal of the transmit / receive isolation switch 18, is maintained at 0. This electrically isolates the receiver RX and the second transmitter TXL from the first transmitter TXH, preventing the application of a pulse signal-based voltage to the receiver RX and the second transmitter TXL.

[0057] Next, we will explain the reception state. As shown in charts (a) and (b), in the reception state, both the control signal SW and the control signal CWbar are at a high potential LV+. Therefore, MOSFETm4 is on, MOSFETm5 is off, and MOSFETm3 is on. When MOSFETm3 is turned on, a current path is formed from the output terminal of the logic buffer BUF through MOSFETm3, Zener diode D1, MOSFETm2, and receiver RX to the ground conductor.

[0058] Therefore, when the voltage of the positive power supply line LV+ is higher than the Zener voltage Vz of the Zener diode D1, the gate potentials of MOSFETs m1 and m2 are equal to the Zener voltage Vz. Conversely, when the voltage of the positive power supply line LV+ is lower than the Zener voltage Vz of the Zener diode D1, the gate potentials of MOSFETs m1 and m2 are equal to LV+. Chart (d) shows an example where the voltage of the positive power supply line LV+ is lower than the Zener voltage Vz of the Zener diode D1, and the gate potentials of MOSFETs m1 and m2 are LV+. Also, the voltage between the gates and sources of MOSFETs m1 and m2 is equal to the Zener voltage Vz.

[0059] MOSFETs m1 and m2 turn on when the voltage between their gates and sources becomes the Zener voltage Vz. As a result, as shown in charts (c) to (e), the potentials of the sources of MOSFETs m1 and m2, and the potential of the drain of MOSFET m2, oscillate in accordance with the vibrations of the ultrasound received by the ultrasonic transducer 14, similar to the transducer voltage. Consequently, a received signal corresponding to the ultrasound arriving at the ultrasonic transducer 14 is input to the input terminal of receiver RX.

[0060] In the receive state, MOSFETm5 is off, and MOSFETm3 is disconnected from the control circuit 16. That is, the drive circuit 20 is disconnected from the control circuit 16 internally, and the transmit / receive separation switch 18 is in the receive-on state. As a result, the noise input from MOSFETm3 to the receiver RX via the transmit / receive separation switch 18 is independent of the operation of the control circuit 16. Therefore, compared to the continuous transmit-on state, the noise contained in the composite signal generated for each sub-array 12 is suppressed.

[0061] Next, we will explain the continuous wave transmission state. As shown in charts (a) and (b), in the continuous wave transmission state, the control signal SW is at a high potential LV+ and the control signal CWbar is at a low potential 0. Therefore, MOSFETm4 is off, MOSFETm5 is on, and MOSFETm3 is on. As a result, the gates of MOSFETm0 and MOSFETm3 in the control circuit 16 are connected, and MOSFETm0 and m3 form a current mirror circuit.

[0062] A constant current source I1 is connected between the drain of MOSFETm0 and the ground conductor, so that a variable or constant current I1 flows from the source to the drain of MOSFETm0. Since MOSFETm0 and m3 form a current mirror circuit, a current I1 also flows from the source to the drain of MOSFETm3 as a control current (a current that depends on the current flowing through the control circuit 16). This current I1 flows through a current path from the output terminal of the logic buffer BUF to the negative power supply line LV- via MOSFETm3, Zener diode D1, MOSFETm2, and the second transmitter TXL. As a result, the voltage between the gate and source of MOSFETm1 and m2 becomes the Zener voltage Vz.

[0063] Because MOSFETm3 operates as a constant current source, the drain of MOSFETm3 has a higher impedance compared to the receiving state, and the potential of the drain of MOSFETm3 can be lower than the high potential LV+. In other words, the gate potentials of MOSFETm1 and m2 can be lower than the high potential LV+.

[0064] As shown in chart (e), a continuous wave signal oscillating in a rectangular pattern from a minimum value LV- to a maximum value LV+ is output from the second transmitter TXL to the drain of MOSFET m2. Since the gate potentials of MOSFET m1 and m2 can be lower than the high potential LV+, the gate potentials of MOSFET m1 and m2 fluctuate in a rectangular pattern from a minimum value LV-+Vz to a maximum value LV+, as shown in charts (d) and (e). Since MOSFET m1 and m2 are on, the source potentials of MOSFET m1 and m2 fluctuate in a rectangular pattern from a minimum value LV- to a maximum value LV+, as shown in chart (d).

[0065] As a result, the transducer voltage fluctuates in a rectangular shape within the range from a minimum value LV- to a maximum value LV+, as shown in chart (c). That is, the continuous wave signal output from the second transmitter TXL is output to the ultrasonic transducer 14 via the transmit / receive separation switch 18.

[0066] In the continuous wave transmission state, the gates of MOSFETm0 and MOSFETm3 in the control circuit 16 are connected, and MOSFETm0 and m3 form a current mirror circuit. That is, in the continuous transmission ON state, the current flowing from the drive circuit 20 to the transmit / receive deactivation switch 18, and further flowing into the main line path of the transmit / receive deactivation switch 18, is controlled according to the operation of the control circuit 16 and the drive circuit 20, and the transmit / receive deactivation switch 18 is in the continuous transmission ON state. Since MOSFETm3 operates as a constant current source, the drain of MOSFETm3 has a higher impedance compared to the receive state. As a result, the range of possible voltages at the second terminal of the transmit / receive deactivation switch 18 is sufficient for the amplitude of the continuous wave signal.

[0067] Figure 4 shows the configuration of an ultrasound diagnostic apparatus 106 according to an applied embodiment of the present disclosure. The ultrasound diagnostic apparatus 106 is an ultrasound diagnostic apparatus 100 with the addition of a receiving input circuit 30 between the transmit / receive separation switch 18 and the receiver RX in the transmit / receive circuit 10.

[0068] The receiving input circuit 30 includes a receiving switch RS and a limiter Lm. The receiving switch RS is connected between the second terminal of the transmit / receive separation switch 18 and the input terminal of the receiver RX. The receiving switch RS may be composed of a switching element such as a MOSFET or a bipolar transistor. A limiter Lm is provided in the path between the receiving switch RS and the receiver RX. The limiter Lm includes clamp diodes D2 and D3. The anode of clamp diode D2 is connected to the ground conductor, and its cathode is connected to the path between the receiving switch RS and the receiver RX. The anode of clamp diode D3 is connected to the path between the receiving switch RS and the receiver RX, and its cathode is connected to the ground conductor.

[0069] The receiver switch RS is turned off when the transmit / receive circuit 10A is in continuous wave transmission mode and turned on when it is in pulse transmission or reception mode. Alternatively, the receiver switch RS may be turned off when the transmit / receive circuit 10A is in continuous wave transmission or pulse transmission mode and turned on when it is in reception mode. The limiter Lm limits the potential in the path between the receiver switch RS and the receiver RX to a range from a lower limit of -Vf to an upper limit of +Vf, where Vf is the forward voltage of clamp diodes D2 and D3.

[0070] In other words, the limiter Lm maintains the potential of the path between the receiving switch RS and the receiver RX when it is between -Vf and +Vf. If the potential of the path between the receiving switch RS and the receiver RX is about to fall below -Vf, the limiter Lm sets it to -Vf. If the potential of the path between the receiving switch RS and the receiver RX is about to exceed +Vf, the limiter Lm sets it to +Vf. In this way, the limiter Lm defines the maximum fluctuation range of the potential of the path between the receiving switch RS and the receiver RX.

[0071] With this configuration, in the receiving state, the amplitude of the voltage input to receiver RX is limited to a range from a lower limit of -Vf to an upper limit of +Vf. As a result, even if the magnitude of the received signal accidentally exceeds the forward voltage Vf of clamp diodes D2 and D3, the magnitude of the voltage applied to receiver RX is limited to the forward voltage Vf, thus avoiding electrical stress on receiver RX.

[0072] Furthermore, when the second transmitter TXL outputs a continuous wave signal, the output terminal of the second transmitter TXL and the input terminal of the receiver RX are disconnected. Therefore, the amplitude of the continuous wave signal is fixed regardless of the forward voltage Vf of the clamp diodes D2 and D3. Also, a continuous wave signal with a larger amplitude than that of the transmit / receive circuit 10 shown in Figure 2 may be output from the second transmitter TXL. Note that the receive input circuit 30 does not necessarily have to use a limiter Lm, and may exclusively use a receive switch RS.

[0073] The above describes an embodiment in which the transmitting / receiving circuit (10,10A) in the ultrasonic probe 102 comprises at least a first transmitter TXH, a transmit / receive separation switch 18, a receiver RX, a delay unit DL, a second transmitter TXL, and a drive circuit 20. One or more of these components of the transmitting / receiving circuit (10,10A) may be provided on the main unit 104 side. For example, the second transmitter TXL may be provided on the main unit 104. In this case, the components provided on the main unit 104 side are connected to the transmitting / receiving circuit (10,10A) in the ultrasonic probe 108 by cable conductors 26.

[0074] Furthermore, the above describes an embodiment in which one control circuit 16 is provided for multiple transmitting and receiving circuits (10, 10A) in an ultrasonic probe (102, 108). The control circuit 16 may be provided for each group of multiple transmitting and receiving circuits (10, 10A) that are divided into multiple groups. That is, the same number of control circuits 16 as the number of groups of transmitting and receiving circuits (10, 10A) may be provided. In this case, the gate of the MOSFETm0 provided in the control circuit 16 is connected to the drive circuit 20 of each transmitting and receiving circuit (10, 10A) belonging to the group corresponding to the control circuit 16. [Explanation of Symbols]

[0075] 10 Transmit / receive circuit, 12 Subarray, 14 Ultrasonic transducer, 16 Control circuit, 18 Transmit / receive separation switch, 20 Drive circuit, 22 Adder, 24 Controller, 26 Cable conductors, 30 Receive input circuit, 100, 106 Ultrasonic diagnostic device, 102, 108 Ultrasonic probe, 104 Main unit, TXH First transmitter, TXL Second transmitter, RX Receiver, DL Delay unit, m0~m5 MOSFET, BUF Logic buffer, I1 Constant current source, D1 Zener diode, D2, D3 Clamp diodes, RS Receive switch, FE Analog front-end circuit.

Claims

1. An ultrasonic transducer driving device provided for each of a plurality of ultrasonic transducers, The ultrasonic transducer is provided with a first transmitter that outputs a first transmission signal, A second transmitter outputs a second transmission signal to the ultrasonic transducer, which has a smaller amplitude than the first transmission signal. A receiver to which the received signal output from the ultrasonic transducer is input, Transmit / receive separation switch, The system includes a drive circuit that controls the transmit / receive separation switch, The first end of the transmit / receive separation switch is connected to the ultrasonic transducer and the output end of the first transmitter. The output terminal of the second transmitter and the input terminal of the receiver are connected to the second terminal of the transmit / receive separation switch. The aforementioned drive circuit is When the first transmitter outputs the first transmission signal, the transmit / receive separation switch is turned off. When the second transmitter outputs the second transmission signal, the transmit / receive separation switch is turned on based on control by a control circuit provided separately from the drive circuit and common to the plurality of ultrasonic transducers. An ultrasonic transducer driving device characterized in that, when the receiving signal is input to the receiver, the transmit / receive separation switch is turned on independently of the control by the control circuit.

2. An ultrasonic transducer driving device according to claim 1, The aforementioned drive circuit is When the second transmitter outputs the second transmission signal, the transmit / receive separation switch is turned on by a control current that depends on the current flowing through the control circuit. An ultrasonic transducer driving device characterized in that, when the receiving signal is input to the receiver, the transmit / receive separation switch is turned on by an independent current separate from the current flowing through the control circuit.

3. The ultrasonic transducer driving device according to claim 2, The aforementioned transmit / receive separation switch is Equipped with two switching elements, Each of the aforementioned switching elements is It includes a first electrode, a second electrode, and a control electrode, and switches the connection between the first electrode and the second electrode on and off according to the voltage between the control electrode and the second electrode. The second electrode and the control electrode of the two switching elements are connected in common, with the first electrode of one of the two switching elements becoming the first end and the first electrode of the other becoming the second end. The aforementioned transmit / receive separation switch further, Each switching element is equipped with a constant voltage device connected between the control electrode and the second electrode, The aforementioned drive circuit is When the second transmitter outputs the second transmission signal, the control current is supplied to the constant voltage device. An ultrasonic transducer driving device characterized in that, when the receiving signal is input to the receiver, the constant voltage device is supplied with its own current.

4. An ultrasonic transducer driving device according to any one of claims 1 to 3, The aforementioned drive circuit is A drive switching element and A communication switch is provided between the drive switching element and the control switching element of the control circuit, The aforementioned communication switch is It turns on when the second transmitter outputs the second transmission signal. The receiver turns off when the received signal is input to it. An ultrasonic transducer driving device characterized in that, when the aforementioned communication switch is turned on, the driving switching element, together with the control switching element, constitutes a current mirror circuit.

5. An ultrasonic transducer driving device according to any one of claims 1 to 3, The input terminal of the receiver is connected to the second terminal of the transmit / receive separation switch via a receive input circuit. The receiving input circuit is, The receiver is provided between the second end of the transmit / receive separation switch and the receiver, The aforementioned receiving switch is An ultrasonic transducer driving device characterized by being turned on when the receiving signal is input to the receiver and turned off when the second transmitter outputs the second transmission signal.

6. The ultrasonic transducer driving device according to claim 5, A limiter is provided between the receiving switch and the receiver, The aforementioned limiter is An ultrasonic transducer driving device characterized by defining the maximum potential fluctuation range of the path between the receiving input circuit and the receiver.

7. Multiple ultrasonic transducers, An ultrasonic transducer driving device according to any one of claims 1 to 3, provided in correspondence with each of the ultrasonic transducers, An ultrasonic probe characterized by comprising the aforementioned control circuit.

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