JP2015058251A - Power source circuit and ultrasonic wave image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source circuit in which increase in the scale of a power source circuit for an ultrasonic wave image display device is suppressed, allowing transmission of ultrasonic wave that requires a large current.SOLUTION: A power source circuit 1 of a transmission circuit that transmits a drive pulse to a vibrator which generates ultrasonic wave includes: a variable voltage power source 2; a first power source line which connects an output terminal of the variable voltage power source 2 to a power source terminal of a transmission circuit 102 through an energy accumulation circuit containing capacitors 4, 8 and constant current circuits 3, 7; a second power source line which directly connects the output terminal of the variable voltage power source 2 to the power source terminal of the transmission circuit 102; and a control part 11 which, based on a transmission condition of ultrasonic wave, performs switching control between a first mode for supplying power to the transmission circuit 102 by using the first power source line and a second mode for supplying power to the transmission circuit 102 by using the second power source line.

Description

  The present invention relates to a technique for improving a power supply circuit in an ultrasonic image display apparatus.

  2. Description of the Related Art An ultrasonic image display device that displays an ultrasonic image based on an echo signal obtained by transmitting ultrasonic waves is known. In recent years, as an image display method in this ultrasonic image display apparatus, a method using ultrasonic waves having a larger energy than conventional ones has been proposed. For example, one method is called dynamic elastography. In this method, an ultrasonic wave called a push pulse is transmitted to a subject to displace a living tissue, and then an ultrasonic wave called a detect pulse is intermittently transmitted to be displaced. This is a method of measuring the propagation velocity of a shear elastic wave (shear wave) generated when the living tissue returns to the original and obtaining the hardness of the living tissue (for example, Patent Document 1, Abstract, FIG. 9 and Patent Document 2). , Paragraph [0004] etc.). Although relatively small energy is sufficient for transmitting the detect pulse, relatively large energy is required for transmitting the push pulse.

  In order to transmit an ultrasonic wave that requires a large amount of energy, it is usually necessary to supply a large amount of power to a transmission circuit that transmits a driving pulse of a probe transducer. In order to supply a large amount of power to the transmission circuit, it is generally necessary to increase the scale of a power supply circuit that supplies power to the transmission circuit.

JP 2010-069295 A JP2012-100997A

However, an increase in the scale of the power supply circuit leads to an increase in cost of parts, and an installation space needs to be expanded as compared with the conventional case. The expansion of the installation space not only makes it difficult to reduce the size of the device, but also requires a significant change in the component layout (layout) inside the device, resulting in increased assembly man-hours and design costs (design).
cost).

  Under such circumstances, in an ultrasonic image display apparatus, it is possible to transmit ultrasonic waves that require large power while suppressing an increase in the scale of a power supply circuit that supplies power to a transmission circuit that transmits drive pulses to a vibrator. Technology is desired.

The invention of the first aspect
A power supply circuit of a transmission circuit that transmits a driving pulse to a vibrator that generates ultrasonic waves for an ultrasonic image display device,
Variable voltage power supply,
A first power line connecting the output terminal of the variable voltage power supply to the power supply terminal of the transmission circuit via a power storage circuit including a constant current circuit and a capacitor;
A second power supply line for directly connecting the output terminal of the variable voltage power supply to the power supply terminal of the transmission circuit;
Based on an ultrasonic transmission condition, a first mode for supplying power to the transmission circuit using the first power line, and a power for the transmission circuit using the second power line. There is provided a power supply circuit including a control unit that performs switching control with a second mode to be supplied.

The invention of the second aspect is
A power supply circuit of a transmission circuit that transmits a driving pulse to a vibrator that generates ultrasonic waves for an ultrasonic image display device,
Variable voltage power supply,
A constant current circuit having an input terminal connected to the output terminal of the variable voltage power source;
A capacitor connected between an output terminal of the constant current circuit and a ground of the variable voltage power supply;
A first switch circuit connected between an output terminal of the constant current circuit and a power supply terminal of the transmission circuit;
A second switch circuit connected between the output terminal of the variable voltage power supply and the power supply terminal of the transmission circuit;
Based on an ultrasonic transmission condition, a first mode in which the first switch circuit is turned on and the second switch circuit is turned off, and the first switch circuit is turned off. And a control unit that performs switching control with respect to the second mode in which the second switch circuit is turned on.

The invention of the third aspect is
When the control unit is in the first mode, the control unit controls the transmission circuit so that ultrasonic energy is constant based on a voltage at a power supply terminal of the transmission circuit. A power supply circuit according to an aspect or a second aspect is provided.

The invention of the fourth aspect is
In the first aspect, the control unit controls the transmission circuit so that the energy of the ultrasonic wave becomes constant based on a drive signal transmitted from the transmission circuit when the control unit is in the first mode. A power supply circuit according to a second aspect is provided.

The invention of the fifth aspect is
The third aspect or the fourth aspect, wherein the control unit controls the transmission circuit so that ultrasonic energy becomes constant by adjusting at least one of an amplitude and a pulse width of the drive pulse. Provide a power supply circuit.

The invention of the sixth aspect is
From the first aspect, the control unit controls to use the first mode when transmitting a first ultrasonic wave that requires more power than the variable voltage power supply can continuously supply. A power supply circuit according to any one of the five aspects is provided.

The invention of the seventh aspect
The power supply circuit according to the sixth aspect is provided, wherein the first ultrasonic wave is a push pulse that generates a shear wave.

The invention of the eighth aspect
The control unit performs control to use the second mode when transmitting a second ultrasonic wave that requires power equal to or lower than power that can be continuously supplied by the variable voltage power source. A power supply circuit according to the seventh aspect is provided.

The invention of the ninth aspect is
The power supply circuit according to any one of the first to eighth aspects, wherein the capacitor has a capacitance of 1 mF (millifarad) or more and 100 mF or less.

The invention of the tenth aspect is
The variable voltage power source has an output terminal that outputs a positive voltage and an output terminal that outputs a negative voltage,
The power supply circuit according to the first aspect is provided, wherein the first power supply line and the second power supply line each have a power supply line for positive voltage and a power supply line for negative voltage.

The invention of the eleventh aspect is
An ultrasonic image display apparatus comprising the power supply circuit according to any one of the first to eleventh aspects is provided.

  According to the invention of the above aspect, in the power supply circuit of the transmission circuit that transmits the drive pulse to the vibrator, when transmitting an ultrasonic wave that requires a large amount of power, power can be supplied from the charged capacitor to the transmission circuit. This makes it possible to transmit ultrasonic waves that require a large amount of power while suppressing an increase in the scale of the power supply circuit.

1 is a diagram showing a configuration of an ultrasonic image display device 100 according to an embodiment of the invention. 1 is a diagram illustrating a configuration of a power supply circuit 1. FIG. It is a figure which shows the power supply circuit 1 when a power supply mode is a high power mode. It is a figure which shows the power supply circuit 1 when a power supply mode is a low power mode. It is a figure which shows the example of a power supply mode and the time change of a drive pulse. It is a figure for demonstrating the droop (droop) which generate | occur | produces in the charge voltage of a large capacity capacitor, and the amplitude of a drive pulse. It is a figure for demonstrating the phenomenon in which the inclination of the droop which generate | occur | produces in the amplitude of a drive pulse changes. It is a figure which shows the 1st modification in embodiment of invention. It is a figure for demonstrating correction | amendment of the drive pulse for making the energy of an ultrasonic wave constant. It is a figure which shows the 2nd modification in embodiment of invention.

  Embodiments of the invention will be described below. The invention is not limited thereby.

  FIG. 1 is a diagram illustrating a configuration of an ultrasonic image display apparatus 100 according to the present embodiment. As shown in FIG. 1, an ultrasonic image display apparatus 100 includes an ultrasonic probe 101, a transmission / reception unit (transmission circuit) 102, a power supply circuit (power supply circuit) 1, an ultrasonic image processing unit 103, a display control unit 104, and a display unit. 105, an operation unit 106 and a control unit 107.

  The ultrasonic probe 101 is provided with a plurality of ultrasonic transducers 101a that transmit and receive ultrasonic waves. When a drive pulse that is a voltage pulse wave is applied to the ultrasonic transducer 101a, an ultrasonic wave is generated and transmitted to the subject.

  The transmission / reception unit 102 transmits a drive pulse to the ultrasonic transducer 101a. In addition, the transmission / reception unit 102 performs phasing addition of the ultrasonic echo signal to form an echo signal for each sound ray. The transmission / reception unit 102 includes a positive power supply terminal, a negative power supply terminal, and a ground terminal. The positive voltage output from the power supply circuit 1 is input to the positive power supply terminal of the transmission / reception unit 102. A negative voltage output from the power supply circuit 1 is input to the negative power supply terminal of the transmission / reception unit 102. The ground terminal of the transmission / reception unit 102 is connected to the power supply ground of the power supply circuit 1.

  The power supply circuit 1 supplies positive and negative voltages used for ultrasonic transmission energy to the transmission / reception unit 102. Details of the power supply circuit 1 will be described later.

  The ultrasonic image processing unit 103 performs processing for creating an ultrasonic image on the echo signal from the transmission / reception unit 102. For example, the ultrasonic image processing unit 103 performs B-mode processing including logarithmic compression processing and envelope detection processing, and color Doppler processing including orthogonal detection processing and filter processing.

  The display control unit 104 scan-converts the signal processed by the ultrasonic image processing unit 103 by a scan converter, and generates ultrasonic image data (data). Then, the display control unit 104 causes the display unit 105 to display an ultrasonic image based on the ultrasonic image data.

  The display unit 105 includes an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or the like.

  The operation unit 106 includes a keyboard (keyboard) and a pointing device (not shown) for an operator to input instructions and information.

  The control unit 107 controls each unit of the ultrasonic image display apparatus 100 so that an ultrasonic image is displayed. The control unit 107 sets ultrasonic transmission conditions according to the operation of the operator. The transmission conditions include, for example, parameters that determine the drive pulse to be transmitted to the ultrasonic transducer 101a, that is, elements that determine the amplitude and pulse width of the drive pulse, the pulse repetition period, and the like. Then, the set transmission condition is transmitted to the power supply control unit 11. The control unit 107 can be realized, for example, by a CPU (Central Processing Unit) reading and executing a predetermined program from a storage unit (not shown).

  Next, the power supply circuit 1 will be described in detail.

  FIG. 2 is a diagram illustrating a configuration of the power supply circuit 1. As shown in FIG. 2, the power supply circuit 1 includes a variable voltage power supply (variable voltage power supply) 2, a positive constant current circuit (constant current circuit) 3, a positive large capacitor (capacitor) 4, and a positive first switch circuit. (First switch circuit) 5, positive second switch circuit (second switch circuit) 6, negative constant current circuit (constant current circuit) 7, negative large capacity capacitor (capacitor) 8, negative first It has a switch circuit (first switch circuit) 9, a negative second switch circuit (second switch circuit) 10, and a power supply control unit (control unit) 11.

  The variable voltage power supply 2 outputs a positive voltage + HV and a negative voltage −HV. The variable voltage power supply 2 has a positive output terminal that outputs a positive voltage + HV, a negative output terminal that outputs a negative voltage −HV, and a ground terminal. The ground terminal of the variable voltage power supply 2 is connected to the ground of the power supply circuit 1. The variable voltage power supply 2 receives control signals from the power supply control unit 11 and changes these voltages. In this example, ± HV is variable up to ± 80V. The power supply control unit 11 sends a control signal to the variable voltage power supply 2 in order to properly adjust the positive and negative voltages ± HV based on the ultrasonic transmission conditions received from the control unit 107. As the variable voltage power supply 2, for example, a power supply circuit proposed in Japanese Patent Application Laid-Open No. 2012-170793 can be used.

  The positive-side constant current circuit 3 has an input terminal to which a positive voltage + HV is input and an output terminal that outputs a current with a constant current. The input terminal of the positive side constant current circuit 3 is connected to the positive side output terminal of the variable voltage power supply 2. The positive-side constant current circuit 3 continues to output current at a constant current until the charging voltage of the positive-side large-capacity capacitor 4 reaches + HV.

  The positive side large-capacity capacitor 4 has a plus terminal and a minus terminal. The positive terminal of the positive-side large-capacity capacitor 4 is connected to the output terminal of the positive-side constant current circuit 3, and the negative terminal of the positive-side large-capacity capacitor 4 is connected to the ground of the power supply circuit 1.

  The positive first switch circuit 5 has an input terminal and an output terminal. The input terminal of the positive first switch circuit 5 is connected to the output terminal of the positive constant current circuit 3, that is, the positive terminal of the positive large capacity capacitor 4. The output terminal of the positive first switch circuit 5 is connected to the positive power supply terminal of the transmission / reception unit 102.

  The positive second switch circuit 6 has an input terminal and an output terminal. The input terminal of the positive second switch circuit 6 is connected to the positive output terminal of the variable voltage power supply 2. The output terminal of the positive second switch circuit 6 is connected to the positive power supply terminal of the transmission / reception unit 102.

  The negative-side constant current circuit 7 has an input terminal to which a negative voltage −HV is input and an output terminal that outputs a current with a constant current. The input terminal of the negative side constant current circuit 7 is connected to the negative side output terminal of the variable voltage power supply 2. The negative-side constant current circuit 7 continues to output current at a constant current until the charging voltage of the negative-side large-capacitance capacitor 8 reaches -HV.

  The negative-side large-capacitance capacitor 8 has a plus terminal and a minus terminal. The negative terminal of the negative side large capacity capacitor 8 is connected to the output terminal of the negative side constant current circuit 7, and the positive terminal of the negative side large capacity capacitor 8 is connected to the ground of the power supply circuit 1.

  The negative first switch circuit 9 has an input terminal and an output terminal. The input terminal of the negative first switch circuit 9 is connected to the output terminal of the negative constant current circuit 7, that is, the negative terminal of the negative large capacity capacitor 8. The output terminal of the negative first switch circuit 9 is connected to the negative power supply terminal of the transmission / reception unit 102.

  The negative second switch circuit 10 has an input terminal and an output terminal. The input terminal of the negative second switch circuit 10 is connected to the negative output terminal of the variable voltage power supply 2. The output terminal of the negative second switch circuit 10 is connected to the negative power supply terminal of the transmission / reception unit 102.

  Each of the positive-side large-capacity capacitor 4 and the negative-side large-capacity capacitor 8 is configured by a parallel connection circuit of a plurality of electrolytic capacitors, for example. Moreover, the capacity | capacitance of the positive side large capacity capacitor 4 and the negative side large capacity capacitor 8 is a mutually same capacity | capacitance, and each is a predetermined capacity | capacitance of 1mF-100mF, for example, respectively.

The positive side first switch circuit 5, the positive side second switch circuit 6, the negative side first switch circuit 9, and the negative side second switch circuit 10 are each controlled by the power supply control unit 11 to turn on / off the switches. Do. The positive first switch circuit 5, the positive second switch circuit 6, the negative first switch circuit 9, and the negative second switch circuit 10 are, for example, a diode, a MOS-FET (Metal-). Oxide-Semiconductor Field-Effect
It is composed of switching elements such as transistors.

  The positive side constant current circuit 3 and the positive side large capacity capacitor 4, and the negative side constant current circuit 7 and the negative side large capacity capacitor 8 respectively form a storage circuit. That is, the positive-side constant current circuit 3 flows current from the positive-side output terminal of the variable voltage power supply 2 into the positive-side large-capacity capacitor 4 at a constant current. When the voltage at the positive terminal of the large-capacity capacitor 4 reaches + HV, the positive-side constant current circuit 3 stops flowing the current and the charging of the positive-side large-capacity capacitor 4 is completed. Similarly, the negative-side constant current circuit 7 performs the same operation as the positive-side constant current circuit 3, and the charging of the negative-side large-capacity capacitor 8 is also completed.

  The positive-side constant current circuit 3 and the positive-side large-capacitance capacitor 4, and the negative-side constant-current circuit 7 and the negative-side large-capacity capacitor 8 are examples of the storage circuit in the invention. Also, a power supply line from the positive output terminal of the variable voltage power supply 2 to the positive power supply terminal of the transmission / reception unit 102 via the positive constant current circuit 3, the positive large capacity capacitor 4, and the positive first switch circuit 5. And a power supply line from the negative output terminal of the variable voltage power supply 2 to the negative power supply terminal of the transmission / reception unit 102 via the negative constant current circuit 7, the negative large capacity capacitor 8, and the negative first switch circuit 9. Is an example of a first power supply line in the invention. In addition, the power line from the positive output terminal of the variable voltage power supply 2 to the positive power supply terminal of the transmitter / receiver 102 via the positive second switch circuit 6 and the negative output terminal of the variable voltage power supply 2 The power supply line to the negative power supply terminal of the transmission / reception unit 102 via the side second switch circuit 10 is an example of a second power supply line in the invention.

The power supply control unit 11 receives ultrasonic transmission conditions from the control unit 107. Then, the power supply control unit 11 performs switching control of the power supply mode and control of the output voltage ± HV of the variable voltage power supply 2 based on the transmission condition. The power supply mode switching control is performed by ON / OFF control of the positive first switch circuit 5, the positive second switch circuit 6, the negative first switch circuit 9, and the negative second switch circuit 10. This power supply control unit 11 is, for example, a programmable IC (programmable, such as a field-programmable gate array (FPGA).
(Integrated Circuit).

  Here, the power supply mode will be described. There are two types of power supply modes, a high power mode and a low power mode.

  The high power mode is a mode used when instantaneously supplying a large amount of power exceeding the power that can be continuously supplied from the variable voltage power supply 2 to the transmission / reception unit 102. In other words, the power supply control unit 11 sets the power supply mode to the high power mode when transmitting ultrasonic waves that require high power exceeding the power that can be continuously supplied by the variable voltage power supply 2.

  FIG. 3 is a diagram illustrating the power supply circuit 1 when the power supply mode is the high power mode. When the high power mode is set, the power supply control unit 11 turns on the positive first switch circuit 5 and the negative first switch circuit 9, and turns on the positive second switch circuit 6 and the negative side, as shown in FIG. Control is performed so that the second switch circuit 10 is turned off. In other words, in the high power mode, the transmission / reception unit 102 receives from the variable voltage power supply 2 the storage circuit including the positive side constant current circuit 3 and the positive side large capacity capacitor 4, and the negative side constant current circuit 7 and the negative side large capacity capacitor 8. Electric power is supplied through the storage circuit. As a result, the transmission / reception unit 102 can transmit drive pulses that require large power exceeding the power that can be continuously supplied by the variable voltage power supply 2 with a relatively long pulse repetition period. For example, a drive pulse for transmitting a push pulse for generating a shear wave, a so-called transverse wave, in the body tissue of a subject may have an amplitude of 100 Vpp or more and a pulse width of 300 μsec or more, which is a conventional variable. It cannot be covered with a voltage power supply. However, after a single push pulse is transmitted, it is usually possible to take a rest time of about several hundreds msec to several sec. Therefore, it is possible to transmit a drive pulse for transmitting a push pulse in this high power mode.

  In the high power mode, the output voltage ± HV of the variable voltage power supply 2 is often controlled to be as large as possible, for example, the maximum output voltage of the variable voltage power supply 2.

  On the other hand, the low power mode is a mode used when supplying power to the transmitting / receiving unit 102 that is equal to or lower than the power that the variable voltage power supply 2 can continuously supply. In other words, the power supply control unit 11 sets the power supply mode to the low power mode when transmitting an ultrasonic wave that requires low power below the power that the variable voltage power supply 2 can continuously supply.

  FIG. 4 is a diagram illustrating the power supply circuit 1 when the power supply mode is the low power mode. When the power control unit 11 sets the low power mode, the positive first switch circuit 5 and the negative first switch circuit 9 are turned off, the positive second switch circuit 6 and the negative side, as shown in FIG. Control is performed so that the second switch circuit 10 is turned on. That is, in the low power mode, the variable voltage power supply 2 and the transmission / reception unit 102 are directly connected, and power is directly transmitted from the variable voltage power supply 2 to the transmission / reception unit 102 without passing through a constant current circuit and a storage circuit with a large capacity capacitor. Supplied. Thereby, the transmission / reception part 102 can transmit the drive pulse which requires the electric power below the electric power which the variable voltage power supply 2 can supply continuously with a comparatively short pulse repetition period. In addition, the transmission / reception unit 102 can instantly receive power supply from the variable voltage power supply 2 at the necessary voltage without waiting for charging / discharging of the large-capacity capacitor, and can respond instantly to changes in drive pulses. can do. In particular, when performing dynamic elastography, it is necessary to transmit a low-power detect pulse immediately after transmitting a high-power push pulse. necessary.

  Hereinafter, the operation of the power supply circuit 1 will be described with reference to examples of drive pulses.

  FIG. 5 is a diagram illustrating an example of the time change of the power supply mode and the drive pulse. In this example, first, in the high power mode, a push pulse for generating a shear elastic wave is transmitted to the subject in a single shot. Immediately thereafter, a detect pulse for detecting the propagation velocity of the shear elastic wave is repeatedly transmitted a plurality of times in the low power mode.

  First, the power supply control unit 11 performs control to set the power supply mode to the high power mode. That is, these switch circuits are set so that the positive first switch circuit 5 and the negative first switch circuit 9 are turned on and the positive second switch circuit 6 and the negative second switch circuit 10 are turned off. To control. Further, control is performed to set the output voltage ± HV of the variable voltage power supply 2 to an optimum voltage for transmission of push pulses, for example, ± 80 V.

  When the voltage ± HV is set to ± 80 V, the positive side large capacity capacitor 4 and the negative side large capacity capacitor 8 are charged until the charging voltage reaches ± 80 V. Accordingly, the supply voltage ± DV of the power supply circuit 1 gradually increases and reaches ± 80V. The supply voltage ± DV of the power supply circuit 1 is also a voltage at the power supply terminal of the transmission / reception unit 102, and is also a charging voltage for the positive-side large-capacity capacitor 4 and the negative-side large-capacitance capacitor 8 in the large power mode.

  When the charging of the positive-side large-capacity capacitor 4 and the negative-side large-capacity capacitor 8 is completed, the power supply control unit 11 transmits a control signal instructing transmission of a push pulse requiring high power to the transmission / reception unit 102. In response to this, the transmission / reception unit 102 generates and transmits a drive pulse DPsw of a push pulse using the charges charged in the positive side large capacity capacitor 4 and the negative side large capacity capacitor 8. The ultrasonic transducer 101a is driven by the drive pulse and transmits a push pulse.

  Immediately after the push pulse is transmitted, it is necessary to immediately transmit a detect pulse for generating the propagation velocity of the shear elastic wave generated in the biological tissue of the subject by the push pulse with a relatively short pulse repetition period. is there.

  Therefore, immediately after the push pulse is transmitted, the power supply control unit 11 performs control to instantaneously switch the power supply mode to the low power mode. That is, these switch circuits are set so that the positive first switch circuit 5 and the negative first switch circuit 9 are turned off and the positive second switch circuit 6 and the negative second switch circuit 10 are turned on. To control. Further, control is performed to set the output voltage ± HV of the variable voltage power supply 2 to an optimum voltage for transmission of the detect pulse, for example, ± 15V.

  The power supply control unit 11 transmits a control signal instructing transmission of the detect pulse to the transmission / reception unit 102. In response to this, the transmission / reception unit 102 receives a plurality of drive pulses DPdt for receiving a power supply from the variable voltage power supply 2 and transmitting a plurality of detect pulses at a relatively short pulse repetition period, for example, several hundred μsec. Generate and send. The ultrasonic transducer 101a is driven by the drive pulse and transmits a plurality of detect pulses.

  As described above, according to the present embodiment, when the power supply mode is the high power mode, the power supply circuit 1 is connected to the transmission / reception unit 102 via the constant current circuit and the power storage circuit including the large-capacitance capacitors 4 and 8. Since it is connected, power can be supplied from the large-capacitance capacitors 4 and 8 charged by the variable voltage power supply 2 to the transmission / reception unit 102, and an ultrasonic wave that requires a large amount of power while suppressing an increase in scale of the power supply circuit 1. Can be sent.

  Further, according to the present embodiment, when the power supply mode is switched from the high power mode to the low power mode, the variable voltage power supply 2 is directly connected to the transmission / reception unit 102 without passing through the power storage circuit. The voltage supplied to the unit 102 can be instantaneously switched to a voltage suitable for ultrasonic transmission that does not require large power. In particular, in this example, the necessary detect pulse can be transmitted immediately after the push pulse is transmitted in the high power mode.

  By the way, in this embodiment, the transmission / reception unit 102 continues to receive power from the charged positive-side large-capacity capacitor 4 and negative-side large-capacitance capacitor 8 while transmitting drive pulses in the high-power mode. Therefore, in the high power mode, while the drive pulse is being transmitted, the charges charged in the positive side large capacity capacitor 4 and the negative side large capacity capacitor 8 continue to decrease, and the absolute charge voltage of these large capacity capacitors is reduced. The values | + DV | and | −DV | That is, as shown in FIG. 6, the supply voltage ± DV of the power supply circuit 1 undergoes a change in which the absolute value of the voltage gradually approaches 0 V as time elapses, that is, a so-called droop. Further, the amplitude of the drive pulse transmitted by the transmission / reception unit 102 is normally determined by the positive and negative voltages supplied to the transmission / reception unit 102. Therefore, with the occurrence of droop in the supply voltage ± DV of the power supply circuit 1, the amplitude of the drive pulse transmitted from the transmission / reception unit 102 also decreases along the droop curve as shown in FIG. .

  On the other hand, it is conceivable that the capacity of the large-capacity capacitor varies among devices due to component variations, or gradually decreases with time due to component deterioration. That is, the slope of the droop of the charging voltage in the large-capacitance capacitor when the drive pulse is transmitted in the high-power mode varies between devices or changes with time. Further, it is considered that the energy of the ultrasonic wave depends on the amplitude and pulse width of the drive pulse. Accordingly, when the droop inclination varies or changes, the time change of the amplitude of the drive pulse does not become constant, and the ultrasonic energy does not become constant.

  For example, consider a case in which a drive pulse DPsw1 of a push pulse as shown in FIG. This drive pulse DPsw1 has a droop slope of α and a pulse width of Δt1. It is assumed that this is changed to the drive pulse DPsw2 as shown in FIG. This drive pulse DPsw2 has a droop gradient that is tighter than α and a pulse width that is Δt1 that is the same as that of the drive pulse DPsw1. In this case, the energy of the push pulse is reduced as much as the droop slope becomes tighter.

  Therefore, a modification for solving this problem will be described below.

(First modification)
FIG. 8 is a diagram showing a first modification in the present embodiment. As shown in FIG. 8, in the first modification, the power supply circuit 1 ′ includes a series circuit of a positive first resistor 24 and a positive second resistor 25, a positive A / D (analog-digital) converter 27. The negative-side first resistor 31 and the negative-side second resistor 32 and a negative-side A / D converter 34 are further included.

  The series circuit of the positive first resistor 24 and the positive second resistor 25 is connected between the positive terminal of the positive large capacity capacitor 4 and the power supply ground. The analog input terminal of the positive side A / D converter 27 is connected to the connection point between the positive side first resistor 24 and the positive side second resistor 25, and the digital output terminal of the positive side A / D converter 27 is The power supply control unit 11 is connected. Similarly, the series circuit of the negative first resistor 31 and the negative second resistor 32 is connected between the negative terminal of the negative large capacitor 8 and the power supply ground. The analog input terminal of the negative A / D converter 34 is connected to the connection point between the negative first resistor 31 and the negative second resistor 32, and the digital output terminal of the negative A / D converter 34 is The power supply control unit 11 is connected. That is, the supply voltage ± DV of the power supply circuit 1 ′, which is the charging voltage of the positive-side large-capacitance capacitor 4 and the negative-side large-capacitance capacitor 8 and also the voltage at the power supply terminal of the transmission / reception unit 102, is divided by resistors. Sampling is performed by the A / D converter, and the data is transmitted to the power supply control unit 11.

  Based on the data, the power supply control unit 11 controls the transmission / reception unit 102 to adjust at least one of the amplitude and pulse width of the drive pulse so that the energy of the push pulse becomes constant. For example, the power supply control unit 11 predicts a droop of the amplitude of the drive pulse from the above data, and calculates a feature amount that represents a time integral of the amplitude of the drive pulse × the pulse width. Then, at least one of the amplitude and the pulse width of the drive pulse is corrected so that the feature amount is always constant. For example, as shown in FIG. 9A, when the slope of the droop is α, the drive pulse DPsw1 having a pulse width Δt1 is transmitted. On the other hand, when the droop slope is tighter than α, as shown in FIG. 9B, the pulse width is set to Δt2 longer than Δt1 so that the time integral of the amplitude of the drive pulse × pulse width is constant. Drive pulse DPsw3 is transmitted.

  According to such a first modification, the energy of the push pulse can be made constant irrespective of the variation due to the variation or deterioration of the capacitance of the large-capacity capacitor.

(Second modification)
FIG. 10 is a diagram illustrating a second modification example of the present embodiment. As shown in FIG. 10, in the second modification, the power supply circuit 1 ″ includes a positive third switch circuit 21, a positive half-wave rectifier circuit 22, a positive low pass filter (Low Pass Filter) circuit 23, and a positive first Series circuit of 1 resistor 24 and positive second resistor 25, positive A / D converter 27, negative third switch circuit 28, negative half wave rectifier circuit 29, negative low pass filter circuit 30, negative first A series circuit of a first resistor 31 and a negative second resistor 32 and a negative A / D converter 34 are further provided.

  One end of the positive-side third switch circuit 21 is connected to one channel among a plurality of output terminals in the transmission / reception unit 102. The other end of the positive third switch circuit 21 is connected to the input terminal of the positive half wave rectifier circuit 22. The output terminal of the positive half-wave rectifier circuit 22 is connected to the input terminal of the positive low-pass filter circuit 23. The series circuit of the positive first resistor 24 and the positive second resistor 25 is connected between the output terminal of the positive low pass filter circuit 23 and the power supply ground. The analog input terminal of the positive side A / D converter 27 is connected to the connection point between the positive side first resistor 24 and the positive side second resistor 25, and the digital output terminal of the positive side A / D converter 27 is The power supply control unit 11 is connected. Similarly, one end of the negative third switch circuit 28 is connected to one channel other than the one channel among the plurality of output terminals in the transmission / reception unit 102. The other end of the negative third switch circuit 28 is connected to the input terminal of the negative half wave rectifier circuit 29. The output terminal of the negative side half-wave rectifier circuit 29 is connected to the input terminal of the negative side low-pass filter circuit 30. The series circuit of the negative first resistor 31 and the negative second resistor 32 is connected between the output terminal of the negative low pass filter circuit 30 and the power supply ground. The analog input terminal of the negative A / D converter 34 is connected to the connection point between the negative first resistor and the negative second resistor, and the digital output terminal of the negative A / D converter 34 is a power source. It is connected to the control unit 11. In other words, if necessary, one or both of the positive and negative third switch circuits are turned on, and the transmitted drive pulse voltage is half-wave rectified for one or both of positive and negative and smoothed by a low-pass filter. (Integration), the voltage is divided by a resistor, sampled by an A / D converter, and the data is transmitted to the power supply control unit 11.

  Based on the data, the power supply control unit 11 controls the transmission / reception unit 102 to adjust at least one of the amplitude and pulse width of the drive pulse so that the energy of the push pulse becomes constant. For example, the power supply control unit 11 predicts a droop of the amplitude of the drive pulse from the above data, and either the amplitude or the pulse width of the drive pulse or the pulse width so that the time integral of the amplitude of the drive pulse × the pulse width is constant or Control both.

  According to such a second modified example, as in the first modified example, the energy of the push pulse can be made constant regardless of the variation due to the variation or deterioration of the capacitance of the large-capacity capacitor.

  In the present embodiment, the case where a push pulse for generating a shear elastic wave is transmitted in the high power mode is described as an example. However, the present invention is not limited to this.

  In the present embodiment, the case where the power supply mode is switched from the high power mode to the low power mode is described as an example, but the present invention is not limited to this. Any combination of high power mode and low power mode can be envisaged.

  Further, in the present embodiment, the transmission / reception unit 102 has a specification that uses both positive and negative voltages as its power supply, but may also be a so-called single power supply specification that uses only positive or negative voltage as its power supply. In this case, the power supply circuits 1 to 1 ″ can be configured to have only a positive or negative circuit.

  In the first and second modified examples, the power supply control unit 11 performs transmission / reception so as to correct the drive pulse based on both positive and negative output voltages in the power supply circuit 1 or both positive and negative voltages in the drive pulse. The unit 102 is controlled. However, more simply, the transmitter / receiver 102 is controlled to correct the drive pulse based on either the positive or negative output voltage of the power supply circuit 1 or the positive or negative voltage of the drive pulse. You may make it do. In this case, the drive voltage may be corrected by predicting the other voltage from one of the positive and negative voltages.

100 Ultrasonic image display device (ultrasonic image display device)
101 Ultrasonic probe 101a Ultrasonic vibrator (vibrator)
102 Transmission / reception unit (transmission circuit)
DESCRIPTION OF SYMBOLS 103 Ultrasonic image processing part 104 Display control part 105 Display part 106 Operation part 107 Control part 1,1 ', 1 "Power supply circuit (power supply circuit)
2 Variable voltage power supply (variable voltage power supply)
3 Positive side constant current circuit (constant current circuit)
4 Positive large-capacity capacitor (capacitor)
5 Positive first switch circuit (first switch circuit)
6 Positive second switch circuit (second switch circuit)
7 Negative constant current circuit (constant current circuit)
8 Negative side large capacity capacitor (capacitor)
9 Negative first switch circuit (first switch circuit)
10 Negative second switch circuit (second switch circuit)
11 Power supply control unit (control unit)
21 Positive side third switch circuit 22 Positive side half-wave rectifier circuit 23 Positive side low-pass filter circuit 24 Positive side first resistor 25 Positive side second resistor 27 Positive side A / D converter 28 Negative side third switch circuit 29 Negative side Half-wave rectifier circuit 30 Negative-side low-pass filter circuit 31 Negative-side first resistor 32 Negative-side second resistor 34 Negative-side A / D converter

Claims (11)

A power supply circuit of a transmission circuit that transmits a driving pulse to a vibrator that generates ultrasonic waves for an ultrasonic image display device,
Variable voltage power supply,
A first power supply line connecting an output terminal of the variable voltage power supply to a power supply terminal of the transmission circuit via a power storage circuit including a constant current circuit and a capacitor;
A second power supply line for directly connecting the output terminal of the variable voltage power supply to the power supply terminal of the transmission circuit;
A first mode for supplying power to the transmission circuit using the first power supply line based on an ultrasonic transmission condition, and a first mode for supplying power to the transmission circuit using the second power supply line. And a control unit that performs switching control between the two modes. A power supply circuit of a transmission circuit that transmits a driving pulse to a vibrator that generates ultrasonic waves for an ultrasonic image display device,
Variable voltage power supply,
A constant current circuit having an input terminal connected to the output terminal of the variable voltage power source;
A capacitor connected between the output terminal of the constant current circuit and the ground of the variable voltage power supply;
A first switch circuit connected between an output terminal of the constant current circuit and a power supply terminal of the transmission circuit;
A second switch circuit connected between the output terminal of the variable voltage power supply and the power supply terminal of the transmission circuit;
Based on an ultrasonic transmission condition, the first switch circuit is turned on and the second switch circuit is turned off, the first switch circuit is turned off, and the first switch circuit is turned off. And a control unit that performs switching control with a second mode in which the two switch circuits are turned on.   The control unit controls the transmission circuit so that ultrasonic energy is constant based on a voltage at a power supply terminal of the transmission circuit in the first mode. The power supply circuit described in 1.   The said control part controls the said transmission circuit so that the energy of an ultrasonic wave may become fixed based on the drive signal transmitted from the said transmission circuit, when it is the said 1st mode. The power supply circuit according to 2.   The said control part controls the said transmission circuit so that the energy of an ultrasonic wave may become fixed by adjusting at least one of the amplitude and pulse width in the said drive pulse, The Claim 3 or Claim 4 is controlled. Power supply circuit.   The said control part is controlled to use a said 1st mode, when transmitting the 1st ultrasonic wave which requires the electric power exceeding the electric power which the said variable voltage power supply can supply continuously. The power supply circuit according to any one of the above.   The power supply circuit according to claim 6, wherein the first ultrasonic wave is a push pulse that generates a shear elastic wave.   The control unit controls to use the second mode when transmitting a second ultrasonic wave that requires power equal to or lower than power that can be continuously supplied by the variable voltage power source. The power supply circuit described in 1.   The power supply circuit according to any one of claims 1 to 8, wherein the capacitor has a capacitance of 1 mF or more and 100 mF or less. The variable voltage power source has an output terminal that outputs a positive voltage and an output terminal that outputs a negative voltage.
2. The power supply circuit according to claim 1, wherein each of the first power supply line and the second power supply line includes a positive voltage power supply line and a negative voltage power supply line. An ultrasonic image display device comprising the power supply circuit according to any one of claims 1 to 10.

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