JP5805961B2 - Power supply circuit for ultrasonic image display device and ultrasonic image display device - Google Patents

Description

  The present invention relates to a power supply circuit for an ultrasonic image display device and an ultrasonic image display device.

  In an ultrasonic image display device that displays an ultrasonic image based on an echo signal obtained by transmitting an ultrasonic wave, a voltage is applied to an ultrasonic vibrator made of a piezoelectric material to vibrate the ultrasonic wave. Sending. Therefore, the ultrasonic image display apparatus is provided with a power supply circuit that supplies ultrasonic transmission power. Conventionally, for example, a flyback converter circuit is used as the power supply circuit (see, for example, Patent Document 1).

JP 2004-236869 A

  The secondary winding of the transformer constituting the flyback converter circuit includes a first secondary winding and a second secondary winding. These first and second secondary windings are included. In the secondary winding, positive and negative voltages used for ultrasonic transmission energy are generated.

  In order to generate a stable ultrasonic transmission pulse, it is desirable to generate a voltage having the same absolute value as a positive and negative voltage (symmetry of positive and negative voltages). However, due to the structure of the transformer, the inductance differs between the first secondary winding and the second secondary winding, and it is difficult to realize an exact symmetry between the positive voltage and the negative voltage. Met.

  In some cases, the power supply circuit for an ultrasonic image display device includes a positive voltage generation unit including a power supply circuit that generates a positive voltage and a negative voltage generation unit including a power supply circuit that generates a negative voltage. In this case, the generated voltage varies between the positive voltage generation unit and the negative voltage generation unit, and there is a case where accurate symmetry between the positive voltage and the negative voltage cannot be realized.

  In one aspect of the invention made in order to solve the above-described problem, the secondary winding is composed of a first secondary winding and a second secondary winding connected in series. A positive output connected to the transformer and an end of the first secondary winding opposite to the second secondary winding and outputs a positive voltage used for ultrasonic transmission energy The negative side that is connected to the line and the end of the second secondary winding opposite to the first secondary winding and outputs a negative voltage used for ultrasonic transmission energy A switching element that induces the positive voltage and the negative voltage by turning on and off an input voltage of an output line and a primary side winding of the transformer, and the positive voltage or the negative voltage becomes a predetermined voltage. A switching control unit for controlling on / off of the switching element Based on the voltage difference between the positive voltage and the negative voltage, a voltage at which the absolute values of the positive voltage and the negative voltage are equal to each other is obtained from the first secondary winding and the second second voltage. A power supply circuit for an ultrasonic image display device, comprising: a feedback circuit that feeds back between the secondary windings.

  In another aspect of the invention, a positive voltage generator that generates a positive voltage used for ultrasonic transmission energy, a negative voltage generator that generates a negative voltage used for ultrasonic transmission energy, Based on the voltage difference between the positive voltage and the negative voltage, a voltage at which the absolute values of the positive voltage and the negative voltage are equal is applied to at least one of the positive voltage generator and the negative voltage generator. A power supply circuit for an ultrasonic image display device, comprising: a feedback circuit for feeding back.

  According to the first aspect of the invention, based on a voltage difference between the positive voltage and the negative voltage, a voltage at which an absolute value of the positive voltage and the negative voltage is equal is the first secondary voltage. Feedback is provided between the side winding and the second secondary winding. Thereby, the exact symmetry of a positive voltage and a negative voltage is realizable.

  According to another aspect of the invention, a voltage at which the absolute values of the positive voltage and the negative voltage are equal based on a voltage difference between the positive voltage and the negative voltage is the positive voltage generator. And feedback to at least one of the negative voltage generator. Thereby, the exact symmetry of a positive voltage and a negative voltage is realizable.

1 is a schematic diagram illustrating an example of an embodiment of an ultrasonic image display device according to the present invention. It is a figure which shows the power supply circuit in the ultrasonic image display apparatus shown in FIG. It is a figure which shows the induced voltage of the both ends of the 1st and 2nd secondary winding in the power supply circuit shown in FIG. It is a figure which shows the positive voltage and negative voltage in case the turns ratio of the 1st and 2nd secondary side winding is a: b. It is a figure explaining the change of an electric current. It is a figure explaining the change of an electric current. It is a figure explaining the change of an electric current. It is a figure explaining the state where the absolute value of the voltage of a positive side output line and the absolute value of the voltage of a negative side output line are equal. It is a block diagram which shows the power supply circuit in the ultrasonic image display apparatus of 2nd embodiment. FIG. 10 is a diagram illustrating a configuration of a power supply circuit illustrated in FIG. 9. It is a figure which shows the structure of the power supply circuit of the modification of 2nd embodiment. It is a block diagram which shows the power supply circuit in the ultrasonic image display apparatus of 3rd embodiment. It is a figure which shows the structure of the power supply circuit shown in FIG. It is a figure which shows the structure of the power supply circuit of the modification of 3rd embodiment. It is a block diagram which shows the power supply circuit in the ultrasonic image display apparatus of 4th embodiment. FIG. 16 is a diagram showing a configuration of a power supply circuit shown in FIG. 15. FIG. 16 is a diagram showing another example of the configuration of the power supply circuit shown in FIG. 15. It is a figure which shows the other example of the power supply circuit of 1st embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, a first embodiment will be described with reference to FIGS. As shown in FIG. 1, the ultrasonic image display apparatus 100 includes an ultrasonic probe 101, a transmission / reception unit 102, an ultrasonic image processing unit 103, a display control unit 104, a display unit 105, an operation unit 106, and a control unit 107. ing. The ultrasonic image display apparatus 100 includes a power supply circuit 1. This power supply circuit 1 is an example of an embodiment of a power supply circuit for an ultrasonic image display device according to the present invention.

  The ultrasonic probe 101 is provided with a plurality of ultrasonic transducers 101a for transmitting and receiving ultrasonic waves. A voltage is applied to the ultrasonic transducer 101a to transmit ultrasonic waves.

  The transmission / reception unit 102 drives the ultrasonic transducer. The transmitter / receiver 102 performs phasing addition of ultrasonic echo signals to form an echo signal for each sound ray. The transmitter / receiver 102 is supplied with positive and negative voltages ± HV used for ultrasonic transmission energy from the power supply circuit 1.

  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 using a scan converter, and generates ultrasonic image 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 is configured by an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or the like. The operation unit 106 includes a keyboard and a pointing device (not shown) for an operator to input instructions and information.

  The control unit 107 includes a CPU (Central Processing Unit). The control unit 107 reads a control program stored in a storage unit (not shown), and executes functions in each unit of the ultrasonic image display device 100.

  Next, the power supply circuit 1 will be described with reference to FIG. As shown in FIG. 2, the power supply circuit 1 includes a power supply 2, a transformer 3, a switching element 4, and a feedback circuit 5.

  The transformer 3 includes a primary side winding 6, a first secondary side winding 7, and a second secondary side winding 8. The first secondary winding 7 and the second secondary winding 8 are connected in series. A positive output line 9 is connected to the end of the first secondary winding 7 opposite to the second secondary winding 8 side. A negative output line 10 is connected to the end of the second secondary winding 8 opposite to the first secondary winding 7 side. The positive voltage + HV is output to the positive output line 9. Further, the negative voltage -HV is output to the negative output line 10. The transformer 3 is an example of an embodiment of a transformer in the present invention. The positive output line 9 is an example of an embodiment of a positive output line in the present invention, and the negative output line 10 is an example of an embodiment of a positive output line in the present invention.

  The switching element 4 is configured by a MOS-FET (Metal-Oxide-Semiconductor Field-Effect Transistor). By turning on the switching element 4, the voltage of the power source 2 is input to the primary winding 6. Then, by switching on and off the input voltage of the primary winding 6 by the switching operation of the switching element 4, a voltage is applied to the first secondary winding 7 and the second secondary winding 8. The induced voltage is output to the positive output line 9 and the negative output line 10 as positive and negative voltages ± HV. The switching element 4 is an example of an embodiment of a switching element in the present invention.

The switching operation of the switching element 4 is controlled by the control unit 11. The control unit 11 includes an IC (Integrated Circuit), and based on the positive voltage + HV of the positive output line 9, the switching element 4 is set so that the positive voltage + HV becomes a predetermined voltage. Feedback control. More specifically, a reference voltage (indicated voltage) V _ref (in this example, V _ref > 0) is also input to the control unit 11. However, the reference voltage V _ref may be generated inside the control unit 11. The control unit 11 compares the reference voltage V _ref with the voltage input from the positive output line 9 side, and based on the comparison result, the positive voltage + HV is a desired voltage (voltage hv described later). The switching element 4 is controlled so that The control unit 11 is an example of an embodiment of a switching control unit in the present invention.

  Incidentally, the positive voltage + HV may not be input as it is to the control unit 11 but a voltage obtained by dividing the positive voltage + HV by a resistor (not shown) may be input.

  The positive output line 9 is provided with a diode D1, and the negative output line 10 is provided with a diode D2. Capacitors C 1 and C 2 are connected between the positive output line 9 and the negative output line 10. The capacitors C1 and C2 are connected to the ground.

  The feedback circuit 5 is an example of an embodiment of the feedback circuit in the present invention, and includes an integrator 12, resistors R1 and R2, and a protection circuit 13. The resistors R1 and R2 are connected in series between the positive output line 9 and the negative output line 10. In this example, it is assumed that the resistance values of the resistor R1 and the resistor R2 are equal. The resistors R1 and R2 are connected to an inverting input (−) of an operational amplifier Op constituting the integrator 12 via an input line 14. Through this input line 14, a voltage difference between the positive voltage + HV and the negative voltage −HV (voltage division according to the resistance values of the resistors R 1 and R 2) is input to the inverting input (−).

  The output line 15 of the operational amplifier Op is connected between the first secondary winding 7 and the second secondary winding 8. Incidentally, the symbol C3 is a capacitor constituting the integrator 12.

  The output line 15 outputs a voltage at which the absolute values of the positive voltage + HV and the negative voltage −HV are equal. Details will be described later.

  The protection circuit 13 is connected to the output line 15. The protection circuit 13 protects the operational amplifier Op from noise (surge noise) caused by ON / OFF of the input voltage in the transformer 3. The protection circuit 13 includes a positive power source + LV and a negative power source −LV connected to the output line 15, a diode D 3 connected between the positive power source + LV and the output line 15, and the positive power source − A diode D4 connected between the LV and the output line 15 is included.

  The diode D1 is connected in such a direction that current flows from the output line 15 to the positive power source + LV. The diode D2 is connected in such a direction that a negative current flows from the output line 15 to the negative power source -LV. Here, the positive power source + LV and the negative power source -LV generate a voltage having the same magnitude as the driving voltage of the operational amplifier Op. Therefore, a surge current from the transformer 3 to the output line 15 flows to the positive power supply + LV side or the negative power supply -LV side, and the operational amplifier Op can be protected.

  Incidentally, the voltage of the positive / negative power supply ± LV and the driving voltage of the operational amplifier Op are set to a voltage lower than the positive / negative voltage ± HV.

  Next, the operation of the power supply circuit 1 will be described. The control unit 11 turns on and off the switching element 4 to turn on and off the input voltage of the primary winding 6. As a result, a voltage corresponding to the winding ratio between the primary side winding 6 and the first secondary side winding 7 is induced at both ends of the first secondary side winding 7, and the primary side winding 7 A voltage corresponding to a winding ratio between the line 6 and the second secondary winding 8 is induced at both ends of the second secondary winding 8, and the positive output line 14 and the negative output line 15 outputs a positive and negative voltage ± HV.

  The induced voltage at both ends of the first secondary winding 7 is + e, and the induced voltage at both ends of the second secondary winding 8 is -e. As shown in FIG. 3, when the potential of the output line 14 is ground, + e becomes the positive voltage + HV and -e becomes the negative voltage -HV (where e> 0).

  Based on the positive voltage + HV of the positive output line 9, the control unit 11 controls the switching element 4 so that the positive voltage + HV becomes a predetermined voltage hv (hv> 0, for example, hv = 100). Feedback control.

  Here, it is assumed that the inductance ratio of the first secondary winding 7 and the second secondary winding 8 is a: b. When the potential of the output line 14 is ground, as shown in FIG. 4, when the positive voltage + HV is + e, the negative voltage −HV (the induced voltage −e) is − {(b / a ) × e}, and | + HV | ≠ | −HV |.

When the absolute value of the voltage of the positive output line 9 (positive voltage + HV) and the absolute value of the voltage of the negative output line 10 (negative voltage −HV) are different from each other, the resistance The current flowing through R1 or the resistor R2 changes. Specifically, assuming that the current flowing through the resistor _R1 is I _R1 and the current flowing through the resistor R2 is I _R2 , if | + HV | = | −HV | = hv, as shown in FIG. , I _R1 = I _R2 = i.

When + HV = hv and −HV = −hv−Δx (| + HV | <| −HV |), as shown in FIG. 6, I _R1 = i, I _R2 = i + Δi, and the capacitor C3 In addition, a current Δi in a direction from the output line 15 toward the input line 14 flows.

Further, when + HV = hv and −HV = −hv + Δx (| + HV |> | −HV |), as shown in FIG. 7, I _R1 = i, I _R2 = i−Δi, and the capacitor C3 In addition, a current Δi in a direction from the input line 14 to the output line 15 flows.

  As described above, since a current flowing through the capacitor C3 is generated, a potential difference is generated between the input line 14 and the output line 15, and the voltage of the output line 15 changes. Specifically, in the case of FIG. 6, the voltage of the output line 15 is high, and in the case of FIG. 7, the voltage of the output line 15 is low. Then, the voltage of the output line 15 settles to a voltage y which finally becomes | + HV | = | −HV | = | hv | as shown in FIG. Specifically, y = [{(b / a) −1} / {(b / a) +1}] × hv.

  As described above, the absolute value | + e | of the induced voltage + e of the first secondary winding 7 and the absolute value | -e | of the induced voltage −e of the second secondary winding 8 Even if there is a variation (| + e | ≠ | −e |), the voltage difference is fed back between the first and second secondary windings 7 and 8 by the feedback circuit, and the integrator 12 As a result, the voltage of the output line 15 becomes y, and | + HV | = | −HV | = | hv |. Therefore, accurate symmetry between the positive voltage and the negative voltage can be realized.

(Second embodiment)
Next, 2nd embodiment is described based on FIG.9 and FIG.10. However, the same components as those of the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

  The power supply circuit 20 of the second embodiment includes a positive voltage generator 21, a negative voltage generator 22, and a feedback circuit 5 'as shown in FIG. A positive output line 23 is connected to the positive voltage generator 21, and a negative output line 24 is connected to the negative voltage generator 22. A reference voltage input line 25 is connected to the positive voltage generator 21 and the negative voltage generator 22. The reference voltage input line 25 is an example of an embodiment of the reference voltage input line in the present invention. Further, the output line 15 of the feedback circuit 5 ′ is connected to the positive voltage generator 21.

  The positive voltage generator 21 has a first power supply circuit 26 as shown in FIG. The first power supply circuit 26 is a power supply circuit having a known configuration, and a detailed configuration is omitted. The first power supply circuit 26 generates the positive voltage + HV from a predetermined voltage and outputs it to the positive output line 23. The positive voltage generator 21 is an example of an embodiment of a positive voltage generator in the present invention.

The first power supply circuit 26 includes a control unit 261. The control unit 261 includes an IC. The control unit 261 receives a voltage (V _ref ′, which will be described later) corrected from the reference voltage V _ref from the reference voltage input line 25. The control unit 261 receives a feedback voltage from a feedback voltage input line 27 connected to the positive output line 23. The control unit 261 compares the corrected reference voltage V _ref ′ with the feedback voltage, and based on the comparison result, the first voltage + HV is set to be equal to | −HV |. The power supply circuit 26 is feedback controlled. The control unit 261 is an example of an embodiment of a control unit in the present invention.

  Incidentally, the feedback voltage input line 27 is an example of an embodiment of the feedback voltage input line in the present invention.

An adder 28 is connected to the reference voltage input line 25 to the positive voltage generator 21. The adder 28 receives a voltage from the feedback circuit 5 'and corrects the reference voltage _Vref so that the absolute value of the positive voltage + HV and the absolute value of the negative voltage -HV are equal. . The adder 28 is an example of an embodiment of a correction unit in the present invention. Details will be described later.

  The negative voltage generator 22 has a second power supply circuit 29. The second power supply circuit 29 is also a power supply circuit having a known configuration, and detailed description thereof is omitted. The second power supply circuit 29 generates the negative voltage −HV from a predetermined voltage and outputs it to the negative output line 24. The negative voltage generator 22 is an example of an embodiment of a negative voltage generator in the present invention.

The second power supply circuit 29 has a control unit 291. The control unit 291 includes an IC. A reference voltage V _ref is input to the control unit 291 from the reference voltage input line 25. The control unit 291 receives a feedback voltage from a feedback voltage input line 30 connected to the negative output line 24. The control unit 291 compares the reference voltage V _ref with the feedback voltage, and feedback-controls the second power supply circuit 29 based on the comparison result so that the negative voltage −HV becomes a desired voltage. .

Incidentally, when the reference voltage V _ref is positive, the control unit 291 compares a voltage obtained by inverting the sign of the reference voltage V _{ref with} the negative voltage −HV.

  The output line 15 from the integrator 12 is connected to the adder 28. Incidentally, the feedback circuit 5 ′ does not have the protection circuit 13.

The operation of the power supply circuit 20 of this example will be described. In the power supply circuit 20 of this example, the positive voltage generator 21 outputs the positive voltage + HV. The negative voltage generator 22 outputs the negative voltage -HV. In an ideal state, the absolute value of the positive voltage + HV and the absolute value of the negative voltage −HV are both equal to a desired voltage (| + HV | = | −HV |). However, in actuality, a voltage having a magnitude different from the desired voltage may be output and | + HV | ≠ | −HV |. In this case, the reference voltage V _ref is corrected by the action of the integrator 12, and the corrected reference voltage V _ref ′ is input to the control unit 261 of the positive voltage generation unit 21, so that the absolute value of the positive voltage + HV is obtained. The value becomes equal to the absolute value of the negative voltage -HV.

More specifically, for example, when the state of | + HV | <| −HV | is reached, the voltage of the output line 15 increases by Δz as described with reference to FIG. Δz is added to the reference voltage V _ref by the adder 28, and V _ref ′ = V _ref + Δz is input to the control unit 261 as the corrected reference voltage V _ref ′. When the reference voltage increases in this way, the control unit 261 controls the first power supply circuit 26 so that the positive voltage + HV increases. Then, the voltage of the output line 15 settles to a voltage at which a reference voltage V _ref ′ finally obtained by | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, the positive voltage + HV rises and becomes equal to the absolute value of the negative voltage −HV (| + HV | = | −HV |).

On the other hand, when the state becomes | + HV |> | −HV |, the voltage of the output line 15 becomes lower by Δz as described with reference to FIG. Accordingly, −Δz is added by the adder 28 (ie, Δz is subtracted), and V _ref ′ = V _ref −Δz is input to the control unit 261 as the corrected reference voltage V _ref ′. . When the reference voltage decreases in this way, the control unit 261 controls the first power supply circuit 26 so that the positive voltage + HV decreases. Then, the voltage of the output line 15 settles to a voltage at which a reference voltage V _ref ′ finally obtained by | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, the positive voltage + HV decreases and becomes equal to the absolute value of the negative voltage −HV (| + HV | = | −HV |).

According to this example described above, even if the absolute values of the positive voltage + HV and the negative voltage −HV vary, the reference voltage V _ref input to the control unit 261 is corrected, and the positive voltage The absolute value of + HV is increased or decreased so as to be equal to the absolute value of the negative voltage −HV. Therefore, accurate symmetry between the positive voltage and the negative voltage can be realized.

Next, a modification of the second embodiment will be described. In this modification, as shown in FIG. 11, a subtracter 31 is provided in the feedback voltage input line 27 instead of the adder 28. The output line 15 is connected to the subtractor 31. Accordingly, the control unit 261 receives the reference voltage V _ref as it is, while receiving the feedback voltage corrected by the subtractor 31. The controller 261 controls the first power supply circuit 26 by comparing the corrected feedback voltage with the reference voltage _Vref . The subtractor 31 is an example of an embodiment of a correction unit in the present invention.

  In this modification, when the state of | + HV | <| −HV | is reached and the voltage of the output line 15 increases by Δz, Δz is subtracted from the feedback voltage + FV by the subtractor 31, and the control unit 261. Is supplied with + FV−Δz as a corrected feedback voltage. When the feedback voltage decreases in this way, the control unit 261 controls the first power supply circuit 26 so that the positive voltage + HV increases. Then, the voltage of the output line 15 settles down to a voltage at which a feedback voltage of finally | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, the positive voltage + HV rises and becomes equal to the absolute value of the negative voltage −HV (| + HV | = | −HV |).

  On the other hand, when the state of | + HV |> | −HV | is reached and the voltage of the output line 15 decreases by Δz, −Δz is subtracted from the feedback voltage + FV by the subtractor 31 (that is, Δz is added). The control unit 261 receives + FV + Δz as the corrected feedback voltage. When the feedback voltage increases in this way, the control unit 261 controls the first power supply circuit 26 so that the positive voltage + HV decreases. Then, the voltage of the output line 15 settles down to a voltage at which a feedback voltage of finally | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, the positive voltage + HV decreases and becomes equal to the absolute value of the negative voltage −HV (| + HV | = | −HV |).

  In this modification, even if the absolute values of the positive voltage + HV and the negative voltage −HV vary, the feedback voltage input to the control unit 261 is corrected, and the absolute value of the positive voltage + HV is changed to the absolute value of the positive voltage + HV. The negative voltage rises or falls to be equal to the absolute value of HV. Therefore, accurate symmetry between the positive voltage and the negative voltage can be realized.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. However, the same components as those of the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

In the power supply circuit 40 of the third embodiment, the output line 15 of the feedback circuit 5 ′ is connected to the negative voltage generator 22. More specifically, a subtractor 41 is provided in the reference voltage input line 25 to the second power supply circuit 29, and the output line 15 is connected to the subtractor 41. Accordingly, the reference voltage V _ref ′ corrected by the subtracter 41 is input to the control unit 291. The control unit 291 controls the second power supply circuit 29 by comparing a voltage obtained by inverting the sign of the reference voltage V _ref ′ with the feedback voltage. The subtractor 41 is an example of an embodiment of a correction unit in the present invention.

In the power supply circuit 40 of this example, the state becomes | + HV | <| −HV |, and when the voltage of the output line 15 becomes higher by Δz, Δz is subtracted from the reference voltage V _ref by the subtractor 41, The control unit 291 receives V _ref ′ = V _ref −Δz as the corrected reference voltage V _ref ′. When the reference voltage decreases in this way, the control unit 291 controls the second power supply circuit 29 so that the negative voltage −HV increases (so that | −HV | becomes smaller). Then, the voltage of the output line 15 settles to a voltage at which a reference voltage V _ref ′ finally obtained by | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, | −HV | becomes smaller and equal to the absolute value of the positive voltage + HV (| + HV | = | −HV |).

On the other hand, when the state becomes | + HV |> | −HV | and the voltage of the output line 15 becomes lower by Δz, −Δz is subtracted from the reference voltage V _ref by the subtractor 41 (that is, Δz is added). The control unit 291 receives V _ref ′ = V _ref + Δz as the corrected reference voltage V _ref ′. When the reference voltage increases in this way, the control unit 291 controls the second power supply circuit 29 so that the negative voltage −HV decreases (so that | −HV | increases). Then, the voltage of the output line 15 settles to a voltage at which a reference voltage V _ref ′ finally obtained by | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, | −HV | becomes larger and becomes equal to the absolute value of the positive voltage + HV (| + HV | = | −HV |).

According to the present example described above, even if the absolute values of the positive voltage + HV and the negative voltage -HV vary, the reference voltage V _ref input to the control unit 291 is corrected, and the negative voltage The absolute value of −HV is increased or decreased so as to be equal to the absolute value of the positive voltage + HV. Therefore, accurate symmetry between the positive voltage and the negative voltage can be realized.

Next, a modification of the third embodiment will be described. In this modification, as shown in FIG. 14, a subtracter 42 is provided in the feedback voltage input line 27 instead of the subtracter 41. The output line 15 is connected to the adder 42. Therefore, the control unit 291 receives the reference voltage V _ref as it is and the feedback voltage corrected by the subtractor 42. The controller 291 controls the second power supply circuit 29 by comparing the corrected feedback voltage with the reference voltage _Vref . The subtractor 42 is an example of an embodiment of a correction unit in the present invention.

  In this modification, when the state of | + HV | <| −HV | is reached and the voltage of the output line 15 increases by Δz, Δz is subtracted from the feedback voltage −FV by the subtractor 42, and the control unit -FV-Δz is input to 291 as the corrected feedback voltage. When the feedback voltage decreases in this way (that is, when the absolute value of the negative voltage fed back | −HV | increases), the control unit 291 increases (| −HV |) so that the negative voltage −HV increases. The second power supply circuit 29 is controlled so that the second power supply circuit 29 becomes smaller. Then, the voltage of the output line 15 settles down to a voltage at which a feedback voltage of finally | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, | −HV | increases and becomes equal to the absolute value of the positive voltage + HV (| + HV | = | −HV |).

  On the other hand, when the state of | + HV |> | −HV | is reached and the voltage of the output line 15 decreases by Δz, −Δz is subtracted from the feedback voltage −FV by the subtractor 31 (that is, Δz is added). -FV + Δz is input to the control unit 291 as the corrected feedback voltage. When the feedback voltage increases in this way (that is, when the absolute value | -HV | of the negative voltage fed back decreases), the control unit 291 causes the negative voltage -HV to decrease (| -HV). The second power supply circuit 29 is controlled so that | Then, the voltage of the output line 15 settles down to a voltage at which a feedback voltage of finally | + HV | = | −HV | is obtained by the action of the integrator 12. As a result, | −HV | increases and becomes equal to the absolute value of the positive voltage + HV (| + HV | = | −HV |).

  In this modification, even if the absolute values of the positive voltage + HV and the negative voltage −HV vary, the feedback voltage input to the control unit 291 is corrected so that the absolute value of the negative voltage −HV is It rises or falls to be equal to the absolute value of the positive voltage + HV. Therefore, accurate symmetry between the positive voltage and the negative voltage can be realized.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. However, the same components as those of the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

  In the power supply circuit 50 of the fourth embodiment, the output line 15 is connected to the positive voltage generator 21 and the negative voltage generator 22. The output line 15 may be connected to the reference voltage input line 25 as shown in FIG. 16, or may be connected to the feedback voltage input lines 27 and 30 as shown in FIG. .

In the case of FIG. 16, in the adder 28 provided in the reference voltage input line 25 to the first power supply circuit 26, the voltage of the output line 15 is added to the reference voltage _Vref . Further, in the subtracter 41 provided in the reference voltage input line 25 to the second power supply circuit 29, the voltage of the output line 15 is subtracted from the reference voltage _Vref . Thereby, even if the absolute values of the positive voltage + HV and the negative voltage −HV vary (| + HV | ≠ | −HV |), the reference voltage to the control units 261 and 291 is corrected, and | + HV | And | −HV | settle to a voltage intermediate between these | + HV | and | −HV |, so that | + HV | = | −HV |.

  In the case of FIG. 17, in the subtractor 31 provided in the feedback voltage input line 27, the voltage of the output line 15 is subtracted from the feedback voltage + FV. Further, in the subtractor 42 provided in the feedback voltage input line 30, the voltage of the output line 15 is subtracted from the feedback voltage -FV. As a result, even if the absolute values of the positive voltage + HV and the negative voltage −HV vary (| + HV | ≠ | −HV |), the feedback voltage to the control units 261 and 291 is corrected, and | + HV | | −HV | settles at a voltage intermediate between | + HV | and | −HV |, and becomes | + HV | = | −HV |.

  As mentioned above, although this invention was demonstrated by the said embodiment, of course, this invention can be variously implemented in the range which does not change the main point. For example, in the power supply circuit 1 of the first embodiment, as shown in FIG. 18, a resistor R3 connected to the ground may be connected between the resistors R1 and R2. By this resistor R3, the voltage of the input line 14 becomes lower than when the resistor R3 is not connected, and the voltage input to the integrator 12 can be adjusted.

1, 20, 40, 50 Power circuit 3 Transformer 4 Switching element 5, 5 ′ Feedback circuit 6 Primary winding 7 First secondary winding 8 Second secondary winding 9, 23 Positive output line 10, 24 Negative output line 11 Control unit (switching control unit)
12 integrator 13 protection circuit 15 output line 21 positive voltage generator 22 negative voltage generator 25 reference voltage input line 27, 30 feedback voltage input line 28 adder (correction unit)
31, 41, 42 Subtractor (correction unit)
261 Control unit (control unit)
291 Control unit

Claims (12)

A transformer in which a secondary winding is composed of a first secondary winding and a second secondary winding connected in series;
A positive output line connected to an end of the first secondary winding opposite to the second secondary winding and outputting a positive voltage used for ultrasonic transmission energy;
A negative output line connected to an end of the second secondary winding opposite to the first secondary winding, and outputting a negative voltage used for ultrasonic transmission energy; ,
A switching element for inducing the positive voltage and the negative voltage by turning on and off the input voltage of the primary winding of the transformer;
A switching control unit for controlling on / off of the switching element so that the positive voltage or the negative voltage becomes a predetermined voltage;
A voltage obtained by dividing a positive voltage and a negative voltage at a voltage dividing point is input, and a voltage is output between the first secondary winding and the second secondary winding to be fed back. A voltage feedback circuit between the first secondary winding and the second secondary winding based on a voltage difference between the positive voltage and the negative voltage. A feedback circuit that outputs a voltage such that the absolute value of the positive voltage and the negative voltage are equal , and the potential at the voltage dividing point is zero ;
A power supply circuit for an ultrasonic image display device. A positive voltage generator for generating a positive voltage used for ultrasonic transmission energy;
A negative voltage generator for generating a negative voltage used for ultrasonic transmission energy;
A feedback circuit that receives a voltage obtained by dividing a positive voltage and a negative voltage at a voltage dividing point, outputs a voltage to at least one of the positive voltage generator and the negative voltage generator, and feeds back the voltage. A voltage fed back to at least one of the positive voltage generator and the negative voltage generator based on a voltage difference between the positive voltage and the negative voltage, and an absolute value of the positive voltage and the negative voltage. A feedback circuit that outputs a voltage so that the potential at the voltage dividing point is zero, and the voltages are equal in value;
A power supply circuit for an ultrasonic image display device. The positive voltage generator includes a controller that controls the positive voltage to a predetermined voltage,
A reference voltage from a reference voltage input line is input to the control unit, and a feedback voltage is input from a feedback voltage input line connected to a positive output line that outputs the positive voltage.
The control unit compares the reference voltage and the feedback voltage, and feedback-controls the positive voltage generation unit so that the positive voltage becomes the predetermined voltage. Power supply circuit for ultrasonic image display apparatus. The negative voltage generator has a controller that controls the negative voltage to a predetermined voltage,
A reference voltage from a reference voltage input line is input to the control unit, and a feedback voltage is input from a feedback voltage input line connected to the negative output line that outputs the negative voltage,
The control unit compares the reference voltage with the feedback voltage, and feedback-controls the positive voltage generation unit so that the positive voltage becomes the predetermined voltage. A power supply circuit for an ultrasonic image display device according to claim 1.   5. The ultrasonic image display power supply circuit according to claim 3, wherein the feedback circuit inputs a voltage to the reference voltage input line or the feedback voltage input line. 6. The reference voltage input line is provided with a correction unit that receives the voltage from the feedback circuit and corrects the reference voltage,
The voltage input to the correction unit from the feedback circuit is a voltage whose reference voltage is corrected so that absolute values of the positive voltage and the negative voltage are equal to each other. Power supply circuit for ultrasonic image display apparatus. The feedback voltage input line is provided with a correction unit that receives the voltage from the feedback circuit and corrects the feedback voltage.
The voltage input to the correction unit from the feedback circuit is a voltage whose feedback voltage is corrected so that absolute values of the positive voltage and the negative voltage are equal to each other. Power supply circuit for ultrasonic image display apparatus.   The power supply circuit for an ultrasonic image display device according to claim 1, wherein the feedback circuit includes an integrator.   The power supply circuit for an ultrasonic image display device according to any one of claims 1 to 8, further comprising a protection circuit that protects the feedback circuit from surge noise.   The power supply circuit for an ultrasonic image display device according to claim 9, wherein the protection circuit is connected to an output line of the feedback circuit.   The protection circuit includes a power supply unit having the same voltage as an operating voltage of an integrator constituting the feedback circuit, and a diode provided between the power supply unit and an output line of the feedback circuit. The power supply circuit for an ultrasonic image display device according to claim 9 or 10.   An ultrasonic image display device comprising the power supply circuit for an ultrasonic image display device according to claim 1.

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