JP2008194290A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide ultrasonic diagnostic equipment generating transmission pulses at a plurality of different voltage levels without increasing the scale of transmission circuits and the number of power supplies. <P>SOLUTION: This ultrasonic diagnostic equipment 1 is provided with a plurality of ultrasonic transducers 3 for transmitting/receiving ultrasonic waves, and a plurality of transmission circuits 2 for actuating the plurality of ultrasonic transducers 3 respectively. The transmission circuits 2 are provided with resistance value variable means SW1, SW2, SW3, SW4, R11, R12, R21 and R22 for varying output resistance values of the transmission circuits 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus that collects and displays biological information such as a tomographic image and a three-dimensional image in a subject by transmitting and receiving ultrasonic waves in the subject with an ultrasonic probe, and particularly for transmission. The present invention relates to an ultrasonic diagnostic apparatus including a transmission circuit capable of applying transmission pulses having different voltage levels to a single ultrasonic transducer.

  An ultrasonic diagnostic apparatus is an image diagnostic apparatus that non-invasively obtains a tomographic image of a tissue in a subject by transmitting and receiving ultrasonic waves in the subject (see, for example, Patent Document 1). The transmission circuit of the ultrasonic diagnostic equipment is a piezoelectric ceramic array ultrasonic vibration that transmits and receives ultrasonic waves by turning on and off the DC (Direct Current) power supply voltage using switches such as bipolar transistors and FETs (Field-Effect Transistors). The child is pulse-driven at a high voltage.

  A transmission circuit is provided for each piezoelectric ceramic array ultrasonic transducer. When there are a large number of array ultrasonic waves, such as a two-dimensional array ultrasonic transducer, multiple ultrasonic transducers can be connected to the transmission circuit in parallel. A technique for reducing the number of transmission circuits by switching ultrasonic transducers connected to the transmission circuits with a switch has been devised.

  On the other hand, in order to improve the image quality of an ultrasonic tomogram or to realize various ultrasonic imaging technologies, a transmission circuit that outputs transmission pulses of different pulse voltages to an ultrasonic transducer has been devised. Specifically, a plurality of pulsers are connected in parallel to a single ultrasonic transducer in order to control the pulse voltage, ie, amplitude, of the first and second transmission pulses, and each pulser is connected to each other. A method of switching a pulser that outputs a transmission pulse to an ultrasonic transducer by connecting to an individual power source has been devised.

  FIG. 9 is a circuit diagram showing a configuration of a transmission circuit in a conventional ultrasonic diagnostic apparatus.

  As shown in FIG. 9, in a transmission circuit of a conventional ultrasonic diagnostic apparatus, a P (positive) channel FET is applied to an ultrasonic transducer composed of titanium ceramic zircon zinc (PZT) or MUT (micromachined ultrasonic transducers). The drain electrode of M1 and the N (negative) channel FET M2 drain electrode are connected. Power sources VP and VN are connected to the source electrodes of the P-channel FET M1 and the N-channel FET M2, respectively. Further, a gate drive circuit Drv for driving the gates of the P-channel FET M1 and the N-channel FET M2 is connected to the trigger control circuit 4 (Trigger Control). The transmission circuit is configured such that one of the P-channel FET M1 and the N-channel FET M2 is turned ON when a control signal is given from the trigger control circuit 4 to the gate drive circuit Drv.

  FIG. 10 is a timing chart showing the operation of the transmission circuit shown in FIG.

  When the gate voltage G1 on the P-channel FET M1 side falls, the P-channel FET M1 is turned ON, and the power supply voltage VP is supplied to the ultrasonic transducer. Also, the gate voltage G1 on the P-channel FET M1 side is returned, and the gate voltage G2 on the N-channel FET M2 side is raised to turn on the N-channel FET M2, and the voltage applied to the ultrasonic transducer is the power supply voltage VN It becomes. As a result, a transmission pulse having a predetermined output voltage (OUTPUT) is applied from the transmission circuit to the ultrasonic transducer. That is, if the power supply voltage VN is a GND level voltage, the output pulse of the output voltage is applied to the ultrasonic transducer for the time when the gate voltage G1 on the P-channel FET M1 side falls.

  Then, by temporally controlling the gate voltages G1 and G2 supplied to the P-channel FET M1 and the N-channel FET M2, respectively, a desired number of transmission pulses are transmitted to the ultrasonic transducer with a desired pulse width. Can be added. Further, the output voltage of the transmission pulse can be changed by changing the power supply voltages VP and VN.

  FIG. 11 is a circuit diagram showing a configuration of another transmission circuit in the conventional ultrasonic diagnostic apparatus.

  In the transmission circuit shown in FIG. 11, the drain electrodes of two P-channel FETs M11 and M21 and the drain electrodes of two N-channel FETs M12 and M22 are connected to an ultrasonic transducer composed of PZT and MUT. The Separate power sources VP1, VP2, VN1, and VN2 are connected to the source electrodes of the two P-channel FETs M11 and M21 and the two N-channel FETs M12 and M22, respectively. Further, a gate drive circuit Drv for driving the gates of the P-channel FETs M11 and M21 and the N-channel FETs M12 and M22 is connected to the trigger control circuit 4 (Trigger Control).

  The transmission circuit is configured such that one of the P-channel FETs M11 and M21 and the N-channel FETs M12 and M22 is turned ON when a control signal is given from the trigger control circuit 4 to the gate drive circuit Drv. . In the transmission circuit shown in FIG. 11, since one ultrasonic transducer is connected to a total of four types of power sources VP1, VP2, VN1, and VN2 via FETs M11, M21, M12, and M22, four types of output voltages are provided. Can be output to the ultrasonic transducer.

  FIG. 12 is a timing chart showing the operation of the transmission circuit shown in FIG.

  By supplying a control signal from the trigger control circuit 4 to each gate drive circuit Drv, for example, as shown in FIG. 12, the gate voltages G11, M22, M21, M12 are applied to the gate electrodes of the corresponding FETs M11, M22, M21, M12. G22, G21, and G12 are supplied. That is, the four FETs M11, M22, M21, and M12 are sequentially turned on / off, and one power source VP1 of the P channel, one power source VN2 of the N channel, the other power source VP2 of the P channel, and the other power source VN1 of the N channel The voltage is controlled so as to be sequentially supplied to the ultrasonic transducer. As a result, a transmission pulse train having output voltages (OUTPUT) at four different voltage levels VP1, VN2, VP2, and VN1 can be applied to the ultrasonic transducer.

That is, by increasing the number of FETs and power sources, it is possible to apply more transmission pulse trains having different voltage levels from the transmission circuit to the ultrasonic transducer.
JP-A-11-290321

  However, in the transmission circuit in the conventional ultrasonic diagnostic apparatus, in order to improve the image quality, that is, to output transmission pulses of different voltage levels, a pulser, FET, and power supply connected in parallel to each ultrasonic transducer It is necessary to increase the number and the type of the voltage according to the type of the amplitude of the voltage level of the controllable transmission pulse. Furthermore, when the power supply increases, the control circuit for the power supply also increases. As a result, there is a problem in that the circuit scale, manufacturing cost, power consumption, and size of the ultrasonic diagnostic apparatus increase.

  Against this background, the larger the control range of the transmission pulse voltage, the higher the image quality and the more displayable functions. Currently, no control function is installed.

  In particular, in the case of an ultrasonic diagnostic apparatus having a large number of ultrasonic transducers, such as an ultrasonic diagnostic apparatus having a two-dimensional (2D) array probe, a plurality of pulsers are provided for each ultrasonic transducer. It is difficult to provide a power source.

  The present invention has been made to cope with such a conventional situation, and an ultrasonic wave capable of generating a plurality of transmission pulses having different voltage levels without increasing the circuit scale of the transmission circuit and the number of power supplies. An object is to provide a diagnostic apparatus.

  In order to achieve the above-described object, an ultrasonic diagnostic apparatus according to the present invention includes a plurality of ultrasonic transducers for transmitting and receiving ultrasonic waves and the plurality of ultrasonic transducers as described in claim 1. And a plurality of transmission circuits to be driven, respectively, and resistance value variable means for varying the output resistance value of the transmission circuit is provided in the transmission circuit.

  In the ultrasonic diagnostic apparatus according to the present invention, a plurality of transmission pulses having different voltage levels can be generated without increasing the circuit scale of the transmission circuit and the number of power supplies.

  Embodiments of an ultrasonic diagnostic apparatus according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention.

  The ultrasonic diagnostic apparatus 1 includes a transmission circuit 2 and an ultrasonic transducer 3. A plurality of ultrasonic transducers 3 are provided, and a transmission circuit 2 corresponding to each ultrasonic transducer 3 is connected thereto. In FIG. 1, only a single ultrasonic transducer 3 and a corresponding transmission circuit 2 are shown. Each transmission circuit 2 is connected to a system control path (not shown). The ultrasonic transducer 3 is made of a piezoelectric ceramic such as PZT or MUT, converts the transmission pulse applied from the transmission circuit 2 into an ultrasonic pulse and transmits the ultrasonic pulse to a subject (not shown), while the supersonic wave generated in the subject. It has a function of receiving a sound wave echo and outputting it as an electrical signal to a receiving circuit (not shown).

  The transmitter circuit 2 includes a P-channel FET M1, an N-channel FET M2, two switches SW1, SW2 on the P-channel side, two resistors R11, R12, a power supply VP, and two switches SW3, SW4, 2 on the N-channel side. Two resistors R21, R22, power supply VN, gate drive circuits Drv1, Drv2 corresponding to each FET M1, M2, multiplexers corresponding to two switches SW1, SW2 on the P channel side (multiplexer: MUltipleXer) MUX1, N channel A multiplexer MUX2 corresponding to the two switches SW3 and SW4 on the side, a trigger control circuit 4 (Trigger Control), and a logic interface circuit 5 (Logic I / F) are provided.

  The drain electrode of the P-channel FET M 1 and the drain electrode of the N-channel FET M 2 are connected to the ultrasonic transducer 3. Three circuits are connected in parallel to the source electrode of the P-channel FET M1 and the source electrode of the N-channel FET M2, respectively. Power supplies VP and VN are connected to the other ends of the circuits connected in parallel, respectively.

  That is, the source electrode of the P-channel FET M1 has a first system connected to the power source VP via the resistor R11, a second system connected to the power source VP via the resistor R12 and the switch SW2, and A third system connected to the power source VP is connected only via the switch SW1. Similarly, the fourth channel connected to the power source VN via the resistor R21 and the fifth channel connected to the power source VN via the resistor R22 and the switch SW4 are connected to the source electrode of the N-channel FET M2. In addition, a sixth system connected to the power source VN is connected only through the switch SW3.

  A common multiplexer MUX1 is connected to the two switches SW1 and SW2 on the P channel side, and a common multiplexer MUX2 is connected to the two switches SW3 and SW4 on the N channel side. Also, corresponding gate drive circuits Drv1, Drv2 are connected to the gate electrode of the P-channel FET M1 and the gate electrode of the N-channel FET M2, respectively. Further, the two gate drive circuits Drv1, Drv2 are connected to a common trigger control circuit 4. The trigger control circuit 4 and the multiplexers MUX1 and MUX2 are connected to a common logic interface circuit 5.

  The trigger control circuit 4 has a function of controlling only one of the P-channel FET M1 and the N-channel FET M2 to be turned on by giving a control signal to the two gate drive circuits Drv1 and Drv2. .

  The multiplexer MUX1 on the P channel side controls ON / OFF of the corresponding two switches SW1 and SW2, and turns off both switches SW1 and SW2. The switch SW1 on the side where the resistor R12 is not connected Three modes are selectable: a second mode in which only the switch is turned on and a third mode in which only the switch SW2 to which the resistor R12 is connected are turned on. Similarly, the multiplexer MUX2 on the N channel side controls the ON / OFF of the corresponding two switches SW3 and SW4 and turns off both the switches SW3 and SW4. The side where the resistor R22 is not connected There are three types of modes: a fifth mode in which only the switch SW3 is turned on and a sixth mode in which only the switch SW4 to which the resistor R22 is connected is turned on.

  The control signal given from the trigger control circuit 4 to the gate drive circuits Drv1 and Drv2 and the control signal given from the multiplexers MUX1 and MUX2 to the corresponding switches SW1, SW2, SW3 and SW4 are sent from the system control circuit (not shown) to the logic interface. The signal is supplied to the trigger control circuit 4 and the multiplexers MUX1 and MUX2 via the circuit 5.

  The logic interface circuit 5 is provided with a timing table. In the timing table, timing information necessary for controlling the pulse width of the transmission pulse output from the transmission circuit 2 is stored. Then, timing information for generating a transmission pulse having a desired pulse width is given from the timing table to each gate drive circuit Drv1, Drv2, and each gate drive circuit Drv1, Drv2 receives each FET M1, at a required timing according to the timing information. It is configured to perform pulse width modulation (PWM) of the transmission pulse by performing M2 ON / OFF control.

  Next, an operation sequence in the transmission circuit 2 of the ultrasonic diagnostic apparatus 1 described above will be described.

  FIG. 2 is a timing chart showing the operation of the transmission circuit 2 shown in FIG.

  On the P channel side and N channel side, when the switches SW1 and SW3 on the side where the resistors R12 and R22 are not connected are ON, the source electrodes of the FETs M1 and M2 are connected to the power sources VP and VN, respectively. . The transmission circuit 2 in this state has the same circuit configuration as the transmission circuit of the conventional ultrasonic diagnostic apparatus shown in FIG.

  When the gate voltage G1 on the P-channel FET M1 falls by the control signals from the two gate drive circuits Drv1 and Drv2, the P-channel FET M1 is turned on and the power supply voltage VP is supplied to the ultrasonic transducer 3. Is done. Also, the gate voltage G1 on the P-channel FET M1 side is returned, and the gate voltage G2 on the N-channel FET M2 side is raised to turn on the N-channel FET M2, and the voltage applied to the ultrasonic transducer 3 is the power supply voltage. VN. As a result, a transmission pulse of a predetermined output voltage OUTPUT 1 is applied from the transmission circuit 2 to the ultrasonic transducer 3. That is, if the power supply voltage VN is a GND level voltage, the transmission pulse of the output voltage OUTPUT 1 is applied to the ultrasonic transducer 3 for the time when the gate voltage G1 on the P-channel FET M1 side falls. become.

  Then, by controlling temporally the gate voltages G1 and G2 supplied to the P-channel FET M1 and the N-channel FET M2, respectively, a desired number of transmission pulses are transmitted to the ultrasonic transducer 3 with a desired pulse width. Can be added. Further, the output voltage of the transmission pulse can be changed by changing the power supply voltages VP and VN.

  That is, when the switches SW1 and SW3 on the side where the resistors R12 and R22 are not connected are ON, the output voltage OUTPUT similar to the output voltage OUTPUT that can be output in the transmission circuit of the conventional ultrasonic diagnostic apparatus shown in FIG. One transmission pulse can be applied to the ultrasonic transducer 3.

  On the other hand, if the switches SW1 and SW3 on the side where the resistors R12 and R22 are not connected are turned off and the switches SW2 and SW4 on the side where the resistors R12 and R22 are connected are turned on, respectively, the source of the P-channel FET M1 The electrode is connected to the power supply VP via two resistors R11 and R12 connected in parallel, and the source electrode of the N-channel FET M2 is connected to the power supply VN via two resistors R21 and R22 connected in parallel. The

  In this case, when the two FETs M1 and M2 are controlled by the same gate voltages G1 and G2 as when only the switches SW1 and SW3 on the side to which the resistors R12 and R22 are not connected are turned on, respectively, as shown in FIG. When the switches SW1 and SW3 on the side to which the resistors R12 and R22 are not connected are turned ON, the transmission pulse of the output voltage OUTPUT 2 with a longer rise time and fall time than the output voltage OUTPUT 1 is ultrasonically vibrated. It can be applied to the child 3.

  When all switches SW1, SW2, SW3, SW4 are turned off, the source electrode of the P-channel FET M1 is connected to the power supply VP via the resistor 11, and the source electrode of the N-channel FET M2 is It is connected to the power supply VN via the resistor R21.

  In this case, if the two FETs M1 and M2 are controlled by the gate voltages G1 and G2 as described above, only the switches SW2 and SW4 on the side to which the resistors R12 and R22 are connected are turned ON as shown in FIG. In this case, the transmission pulse of the output voltage OUTPUT 3 having a longer rise time and fall time than the output voltage OUTPUT 2 can be applied to the ultrasonic transducer 3.

  The pulse width of the transmission pulse is determined by the frequency band of the ultrasonic wave transmitted by the ultrasonic transducer 3. As shown in FIG. 2, when the output voltages OUTPUT 1, OUTPUT 2 and OUTPUT 3 of three types of transmission pulses can be selected, the pulse width of the transmission pulse is equal to the pulse width (1 / 2 lambda), the transmitted pulse is converted to almost the same sound output at the center of the frequency band.

  On the other hand, when viewed from the transmission circuit 2 side, the steeper waveform of the output voltages OUTPUT 1, OUTPUT 2, and OUTPUT 3 causes a greater loss in the transmission circuit 2 due to the influence of parasitic impedance and the like near the output of the transmission circuit 2. In addition, the influence of electromagnetic radiation due to a steep current increases. In other words, if the sound output is the same, delaying the rise and fall of the output voltage as much as possible has better transmission efficiency and has less influence on electromagnetic compatibility (EMC).

  The rise time and fall time of the output voltage are determined by the values of resistors R11, R12, R21, R22 connected in parallel to the FETs M1, M2 and the load impedance of the ultrasonic transducer 3. The ultrasonic transducer 3 is composed of piezoelectric ceramics and has a resonant load impedance. That is, if the material of each ultrasonic transducer 3 is the same, the area of each ultrasonic transducer 3 is larger, and the higher the frequency, the larger the capacity. Therefore, the values of the resistors R11, R12, R21, and R22 in the transmission circuit 2 and the switches SW1, SW2, SW3, and SW4 may be switched by the ultrasonic probe to be used.

  In the diagnosis by the ultrasonic diagnostic apparatus 1, a plurality of ultrasonic probes are selectively used depending on the purpose of use. As the types of ultrasonic probes, there are those that differ in the size of the opening and the material of the ultrasonic transducer 3 in addition to the probe frequency, such as a low-frequency probe and a high-frequency probe. There are also 1D array ultrasound probes, 1.5D array ultrasound probes, and 2D array ultrasound probes.

  The resistance between the power supply VP and VN of the ultrasonic transducer 3 and the transmission circuit 2 is affected by EMC by presetting the ultrasonic probe according to the type of the ultrasonic probe when the ultrasonic probe is attached to the ultrasonic diagnostic apparatus 1. Therefore, efficient ultrasonic transmission can be performed.

  FIG. 1 shows the transmission circuit 2 for switching the resistance value between the power sources VP and VN of the ultrasonic transducer 3 and the transmission circuit 2 in three stages, but depending on the number of types of ultrasonic probes used, The transmission circuit 2 may be configured such that the switch SW and the resistance R are increased and switching can be performed in four or more stages. For example, if the transmission circuit 2 can control 3 bits, 8 types of resistance values can be set, and if the transmission circuit 2 can control 4 bits, 16 types of resistance values can be set. Is possible.

  The switches SW1, SW2, SW3, and SW4 can be switched according to the type of ultrasonic probe to be used, and can be performed for other purposes. As the resistance value between the ultrasonic transducer 3 and the power sources VP and VN is increased, the rise time and the fall time of the output voltage of the transmission pulse become longer. If the rise time and fall time of the output voltage of this transmission pulse are further increased without changing the pulse width, the output voltage will not reach the power supply voltage VP. Using this principle, the value of the output voltage of the transmission pulse can be controlled.

  FIG. 3 is a diagram for explaining a method of controlling the value of the output voltage by increasing the rise time and fall time of the output voltage of the transmission pulse output from the transmission circuit 2 shown in FIG.

  As shown in FIG. 3, as the rise time and fall time of the output voltage of the transmission pulse P are lengthened, the value of the output voltage becomes smaller. Therefore, the value of the output voltage can be controlled by changing the rise time and fall time of the output voltage of the transmission pulse.

  Control of the output voltage of the transmission pulse is useful when performing transmission weighting that weights the amplitude of the ultrasonic pulse transmitted from the plurality of ultrasonic transducers 3. Transmission weighting is effective in reducing side lobes generated at a location different from the focal point of the ultrasonic transmission beam when scanning with an ultrasonic transmission beam formed by a plurality of ultrasonic transducers 3. Each weight of transmission weighting generally has a high ultrasonic pulse voltage transmitted from the ultrasonic transducer 3 corresponding to the center of the ultrasonic array, and the ultrasonic transducer 3 separated from the center of the ultrasonic array. Is determined by the sinc function so that the voltage of the ultrasonic pulse transmitted from is smaller.

  FIG. 4 is a block diagram showing a circuit configuration in the case of controlling the value of the output voltage of the transmission pulse for transmission weighting using the transmission circuit 2 shown in FIG.

  As shown in FIG. 4, pulsars 10 for applying transmission pulses are connected to the plurality of ultrasonic transducers 3 arranged in an array in a one-to-one relationship. That is, each pulser 10 in FIG. 4 corresponds to the transmission circuit 2 shown in FIG. Therefore, in each pulser 10, the resistance value can be switched by switching the switches SW1, SW2, SW3, and SW4 as in the transmission circuit 2 shown in FIG.

  Each pulser 10 is connected to a common trigger control circuit 11Trig. And a common multiplexer 12Apod.MUX. Each pulser 10 is controlled by a control signal from the trigger control circuit 11Trig.

  In addition, by using Apod.MUX, the switches SW1, SW2, SW3, and SW4 are individually switched for each pulsar 10 so that the resistance values of the pulsars 10 can be set to different values. For this reason, the switches SW1, SW1 are set so that the resistance value connected to the ultrasonic transducer 3 on the end side of the ultrasonic array is larger than the resistance value connected to the ultrasonic transducer 3 on the center side of the ultrasonic array. Transmission weighting can be realized by individually switching SW2, SW3, and SW4 or by determining the value of the resistance R connected to the ultrasonic transducer 3.

  Thus, the output resistance value of each pulser 10 can be varied not only for the single ultrasonic transducer 3 but also for each transmission channel.

  Up to this point, the case where the switches SW1, SW2, SW3, and SW4 are not switched after the ultrasonic probe is attached to the ultrasonic diagnostic apparatus 1 has been described. However, the switches SW1, SW2, SW3, and SW4 are switched using the transmission sequence. Can be switched dynamically.

  FIG. 5 is a timing chart showing the voltage change of the transmission pulse for explaining the timing of switching the switches SW1, SW2, SW3, SW4 in the transmission circuit 2 shown in FIG.

  The timing chart of FIG. 5 shows the voltage change when the voltage is changed for each transmission of the ultrasonic transmission beam. As shown in FIG. 5, as one method of contrast contrast mode, there is a case where a high sound pressure ultrasonic transmission beam Bh and a low sound pressure ultrasonic transmission beam Bl are switched and transmitted.

  For example, a high-voltage ultrasonic transmission beam Bh is first transmitted, and in the second to fourth transmissions, the low-voltage ultrasonic transmission beam Bl is used again. In the fifth transmission, the high-voltage ultrasonic transmission beam Bh is used again. Bh may be sent. In this case, by switching the switches SW1, SW2, SW3, and SW4 before the second transmission to the fourth transmission, the transmission of the high-voltage ultrasonic transmission beam Bh without changing the power supply voltages VP and VN and the super-low voltage The transmission of the sound wave transmission beam Bl can be switched.

  In this way, in addition to the video modes such as the B mode, the contrast mode, the color mode, the flash mode, and the monitor mode, the output of the transmission circuit 2 also depends on the type of transmission sequence used and the transmission repetition period of the transmission pulse. The resistance value can be varied.

  Further, when the transmitted ultrasonic wave is a burst wave composed of a plurality of waves other than one wave, the switches SW1, SW2, SW3, SW4 can be switched on the transmission waveform of the burst wave.

  FIG. 6 is a diagram illustrating a waveform of a burst wave output by switching the switches SW1, SW2, SW3, and SW4 on the transmission waveform in the transmission circuit 2 illustrated in FIG.

  Since each FET M1, M2 operates to turn ON alternately, when each FET M1, M2 is OFF, that is, when the other is in the ON period, switching the switches SW1, SW2, SW3, SW4 When ON, each FET M1, M2 can be selected by selecting another resistor. For this reason, by controlling the pulse width of the transmission pulse, as shown in FIG. 6, it is possible to reduce the voltage at the portions before and after the burst wave BW. If the voltage at the front and rear portions of the burst wave BW is controlled so as to follow a Gaussian distribution, it is possible to suppress the second harmonic component of the transmission pulse. Such voltage control of the transmission pulse is effective in the display mode for visualizing the second harmonic component.

  That is, the ultrasonic diagnostic apparatus 1 as described above includes the transmission circuit 2 that can switch the output resistance value. In the ultrasonic diagnostic apparatus 1, the output resistance value of the transmission circuit 2 varies for each ultrasonic probe to be used, for each ultrasonic transmission beam, for each scanning mode, for each transmission channel, or on a transmission waveform. Change according to various conditions.

  Thus, for example, transmission weighting can be performed by changing the output resistance value of the transmission circuit 2 for each transmission channel, and the output of the transmission circuit 2 on the waveform between the first wave and the second wave of the burst wave If the resistance value is changed, a uniform sound field can be formed by transmission in which the second harmonic is suppressed. Further, if the output resistance value of the transmission circuit 2 is changed for each ultrasonic probe, the current flowing into the parasitic capacitance of the output portion is reduced, and the transmission efficiency can be improved. For this reason, power saving of the transmission circuit 2 can be achieved. Furthermore, by increasing the rise time of the transmission pulse, electromagnetic radiation causing unnecessary noise can be reduced and EMC performance can be improved.

  According to the ultrasonic diagnostic apparatus 1, the amplitude of the transmission pulse generated by one system pulser can be controlled to a plurality of different values, so that transmission pulses of a plurality of voltage levels are output from a single power source. Is possible. That is, according to the ultrasonic diagnostic apparatus 1, a plurality of transmission pulses having different voltage levels can be generated without increasing the circuit scale, manufacturing cost, power consumption, and size of the ultrasonic diagnostic apparatus 1 of the transmission circuit 2. it can.

  Further, in the ultrasonic diagnostic apparatus 1, the variable range of the voltage of the transmission pulse can be widened by combining with the PWM. Further, finer and more accurate voltage control of the transmission pulse can be realized.

  FIG. 7 is a block diagram showing a second embodiment of the ultrasonic diagnostic apparatus according to the present invention.

  In the ultrasonic diagnostic apparatus 1A shown in FIG. 7, the ultrasonic switch shown in FIG. 1 is that the four switches SW1, SW2, SW3, and SW4 of the transmission circuit 2A are constituted by FETs M11, M12, M21, and M22, respectively. Different from the device 1. Since other configurations and operations are not substantially different from those of the ultrasonic diagnostic apparatus 1 shown in FIG. 9, the same components are denoted by the same reference numerals and description thereof is omitted.

  That is, in the ultrasonic diagnostic apparatus 1A, the switches SW1, SW2, SW3, and SW4 are configured by FETs M11, M12, M21, and M22, respectively. That is, the two FETs M11 and M12 on the P channel side function as switches by being turned ON / OFF by a control signal from the multiplexer MUX1 on the P channel side. Similarly, the two FETs M21 and M22 on the N channel side function as switches by being turned ON / OFF by a control signal from the multiplexer MUX2 on the N channel side. For this reason, in the ultrasonic diagnostic apparatus 1A, a practical switch operation is possible.

  Since the voltage of the transmission pulse is 100V or higher, the two FETs M1 and M2 on the output side need to be high-voltage FETs, but as switches SW1, SW2, SW3, and SW4 for variable output resistance As the FETs M11, M12, M21, and M22 used, low-voltage FETs are sufficient. Therefore, it is possible to select a small FET for each of the FETs M11, M12, M21, and M22 used as the switches SW1, SW2, SW3, and SW4 for changing the output resistance value, and the circuit scale and manufacture of the transmission circuit 2A can be selected. The increase in cost can be suppressed to a slight extent.

  The FETs M11, M12, M21, and M22 used as the output resistance value variable switches SW1, SW2, SW3, and SW4, respectively, can be selected with a small ON resistance. The ON resistance itself can be varied by changing the gate voltages of M12, M21, and M22.

  FIG. 8 is a block diagram showing a third embodiment of the ultrasonic diagnostic apparatus according to the present invention.

  In the ultrasonic diagnostic apparatus 1B shown in FIG. 8, four switches SW1, SW2, SW3, SW4 and resistors R11, R12, R21, R22 of the transmission circuit 2B are connected to FETs M11 and N for variable resistance on the P channel side. 1 is different from the ultrasonic diagnostic apparatus 1 shown in FIG. 1 in that a resistance variable FET M21 on the channel side is replaced and the multiplexers MUX1 and MUX2 are replaced by bias control circuits BiasCont1 and BiasCont2, respectively. Since other configurations and operations are not substantially different from those of the ultrasonic diagnostic apparatus 1 shown in FIG. 9, the same components are denoted by the same reference numerals and description thereof is omitted.

  That is, in the transmission circuit 2B of the ultrasonic diagnostic apparatus 1B shown in FIG. 8, the FET M11 on the P channel side for changing the output resistance of the transmission circuit 2B is connected to the source electrode of the voltage supply FET M1. The Similarly, an N-channel FET M21 for varying the output resistance of the transmission circuit 2B is connected to the source electrode of the voltage supply FET M2. Bias control circuits BiasCont1 and BiasCont2 are connected to the gate electrodes of the variable resistance FETs M11 and M21, respectively.

  Each of the bias control circuits BiasCont1 and BiasCont2 changes the bias voltage discretely or continuously and supplies the bias voltage to the corresponding variable resistance FETs M11 and M21. As a result, the ON resistances of the variable resistance FETs M11 and M21 change. That is, the output resistance value of the transmission circuit 2B can be varied.

  Like the transmission circuit 2B of the ultrasonic diagnostic apparatus 1B, the output resistance value of the transmission circuit 2B is changed to the ON resistances of the FETs M11 and M21 instead of using the switches SW1, SW2, SW3, SW4 and the resistors R11, R12, R21, R22. It can be realized by changing. In such a transmission circuit 2B of the ultrasonic diagnostic apparatus 1B, the variable range of the output resistance value can be expanded.

  Further, not only the resistance variable FETs M11 and M21 but also the ON resistances of the voltage supply FETs M1 and M2 can be changed. Therefore, it is possible to control the output resistance value of the transmission circuit also by varying the gate drive voltage applied to the corresponding voltage supply FETs M1 and M2 from the respective gate drive circuits Drv1 and Drv2.

  In the ultrasonic diagnostic apparatuses 1, 1 </ b> A, and 1 </ b> B of the above embodiments, the case where the ultrasonic vibrator 3 is a piezoelectric ceramic vibrator has been described. However, the ultrasonic vibrator 3 is a capacitive micromachined ultrasonic wave. Even in the case of a transducer (cMUT: capacitive MUT), the output resistance value of the transmission circuit can be controlled similarly. The cMUT is an ultrasonic transducer 3 in which diaphragms that mechanically vibrate due to electrostatic force are arranged in an array on a silicon substrate. When the ultrasonic transducer 3 is a cMUT, a transmission circuit capable of varying the output resistance value is provided on a silicon substrate constituting the cMUT or on another substrate disposed on the back surface of the silicon substrate. it can. In the case where the ultrasonic transducer 3 has a capacitive load such as a cMUT, the variable function of the output resistance value in the transmission circuit is particularly effective.

  Further, the transmission circuit may be provided either on the apparatus main body side or in the ultrasonic probe. Furthermore, it is not always necessary to provide a transmission circuit whose output resistance value can be varied arbitrarily, and the transmission circuit is configured so that the output resistance of the transmission circuit can be varied for each of the plurality of reception channels. May be.

1 is a configuration diagram showing a first embodiment of an ultrasonic diagnostic apparatus according to the present invention. FIG. 2 is a timing chart showing the operation of the transmission circuit shown in FIG. The figure explaining the method of controlling the value of an output voltage by lengthening the rise time and fall time of the output voltage of the transmission pulse output from the transmission circuit shown in FIG. The block diagram which shows the circuit structure in the case of controlling the value of the output voltage of a transmission pulse for transmission weighting using the transmission circuit shown in FIG. FIG. 2 is a timing chart showing a change in voltage of a transmission pulse for explaining timing for switching a switch in the transmission circuit shown in FIG. 1. FIG. The figure which shows the waveform of the burst wave output by switching a switch on a transmission waveform in the transmission circuit shown in FIG. The block diagram which shows 2nd Embodiment of the ultrasonic diagnosing device which concerns on this invention. The block diagram which shows 3rd Embodiment of the ultrasonic diagnosing device which concerns on this invention. The circuit diagram which shows the structure of the transmission circuit in the conventional ultrasonic diagnostic apparatus. 10 is a timing chart showing the operation of the transmission circuit shown in FIG. The circuit diagram which shows the structure of another transmission circuit in the conventional ultrasonic diagnostic apparatus. 12 is a timing chart illustrating the operation of the transmission circuit illustrated in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Ultrasonic diagnostic apparatus 2, 2A, 2B Transmission circuit 3 Ultrasonic transducer 4 Trigger control circuit 5 Logic interface circuit 10 Pulser 11 Trigger control circuit 12 Multiplexer

Claims (11)

A plurality of ultrasonic transducers for transmitting and receiving ultrasonic waves;
A plurality of transmission circuits that respectively apply transmission pulses to the plurality of ultrasonic transducers,
An ultrasonic diagnostic apparatus, wherein the transmission circuit is provided with resistance value varying means for varying the output resistance value of the transmission circuit. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to switch the output resistance value according to a type of an ultrasonic probe to be used. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to switch the output resistance value according to at least one of a video mode, a transmission sequence, and a transmission repetition period. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to vary the output resistance value for each transmission channel of the transmission pulse. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to switch the output resistance value on a waveform of the transmission pulse. 2. The ultrasonic diagnostic apparatus according to claim 1, further comprising modulation means for performing pulse width modulation of the transmission pulse. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is provided for each transmission channel of the transmission pulse or for each of a plurality of transmission channels. The resistance value varying means is configured to control the output voltage of the transmission pulse by adjusting the rise time and fall time length of the transmission pulse by switching the output resistance value. The ultrasonic diagnostic apparatus according to claim 1. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to vary the output resistance value by switching resistors connected in parallel by a switch. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to vary the output resistance value by switching resistors connected in parallel by a transistor functioning as a switch. The ultrasonic diagnostic apparatus according to claim 1, wherein the resistance value varying unit is configured to vary the output resistance value by varying an ON resistance of a transistor.

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