JP5519981B2 - Transmission circuit of ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a transmission circuit that outputs a transmission signal (positive / negative pulse) to a vibration element.

  The ultrasonic diagnostic apparatus includes a main body including a transmission unit and a reception unit, and an ultrasonic probe connected thereto. An array transducer is generally provided in the ultrasonic probe. The array transducer includes a plurality of vibration elements. A transmission unit supplies a plurality of transmission signals to the array transducer, and the transmission unit includes a plurality of transmission circuits.

  FIG. 4 shows a transmission circuit described in Patent Document 1. The transmission circuit 20 includes a transmission drive circuit 22 and a transmission control circuit 24. A transmission circuit 20 is provided for each vibration element 16. A transmission / reception separation circuit (D3, D4) is provided on the element signal line connected to the vibration element 16. A first switching circuit 200 and a second switching circuit 202 are connected to the element signal line. The first switching circuit 202 has two switching elements Q1, Q2. They are constituted by FETs (the same applies to switching elements Q3 and Q4 described later). The switching element Q1 connects the element signal line to the ground when the switching element Q1 is turned on. A diode D1 is provided between the switching element Q1 and the element signal line. A switching element Q2 is provided between the element signal line and the power source (+ HV). The switching element Q2 connects the power supply to the element signal line when the switching element Q2 is turned on. As a result, a positive pulse is output. A resistor R1 is provided between the power supply and the gate of the switching element Q2. A control signal 25 from the transmission control circuit 24 is input to the gate of the first switching element Q1, and simultaneously input to the gate of the second switching element Q2 via the capacitor C1. The switching element Q1 is turned on and the switching element Q2 is turned off except during positive pulse transmission. At the time of positive pulse transmission, the switching element Q1 is turned off and the switching element Q2 is turned on.

  The second switching circuit 202 includes a switching element Q3 and a switching element Q4. A capacitor C2 for generating a negative pulse is provided between the connection point between the two and the element signal line. The switching element Q4 connects the input side of the capacitor C2 to the power supply during the ON operation. The switching element Q3 connects the input side of the capacitor C2 to the ground when the switching element Q3 is turned on. A protective diode D2 is provided between the source of the switching element Q4 and the input side of the capacitor C2. A control signal 26 from the transmission control circuit 24 is input to the gate of the switching element Q3 and simultaneously input to the gate of the switching element Q4 via the capacitor C3. The control signal VG is a signal having a predetermined potential for turning on the switching element Q4, and the signal is given to the gate of the switching element Q4 via the resistor R2. The switching element Q4 is always in the on state by the supply of the control signal VG except during the negative pulse transmission. That is, + HV is applied to the input side of the capacitor C2 and charged (the output side of the capacitor C2 is 0V). If a control signal 26 is output from the transmission control circuit 24 during negative pulse transmission, the switching element Q4 is turned off and the switching element Q3 is turned on. In a situation where the capacitor C2 is charged, when the potential on the input side is suddenly lowered from + HV to the ground level, the potential on the output side is changed from the ground level to -HV level. In this way, by controlling the operating point of the capacitor in a floating manner, a negative pulse can be generated even though only a one-polarity power source is used. After the negative pulse is generated, the switching element Q3 is turned off and the switching element Q4 is turned on, whereby the capacitor C2 is recharged.

JP 2001-245881 A

  However, in order to realize an inexpensive device, it is desired to use a package IC in which a complementary switching element pair and a peripheral circuit are mounted. In such a case, the control signal VG shown in FIG. It has been pointed out that it is difficult to supply the necessary parts from the outside. Alternatively, when a positive pulse is generated following generation of a negative pulse, there is a possibility that the input side of the capacitor C2 becomes + HV or higher and the capacitor C2 cannot be charged properly. In a mode in which bipolar pulses are transmitted, positive and negative waveform symmetry is required, so there is a high need to solve the problem of insufficient capacitor charging.

  An object of the present invention is to appropriately charge a capacitor for pulse generation.

  An object of the present invention is to improve waveform symmetry when a bipolar pulse is generated using a unipolar power supply.

The present invention is a transmission circuit connected to an oscillating element via an element signal line, the first switching circuit for connecting a power source of one polarity to the element signal line in one polarity pulse output period, and the element By connecting the ground to the input side of the capacitor C2 in the charged state and the capacitor C2 whose output side is connected to the signal line and the other polarity pulse output period, the other polarity pulse is connected to the output side of the capacitor C2. The switching element Q4 provided between the input side of the capacitor C2 and the power supply is turned on by using the second switching circuit for generating the time and the idle time of the transmission / reception sequence, and the capacitor C2 is charged in advance. And a control circuit.

  According to the above configuration, one polarity pulse (for example, positive pulse) is generated by the operation of the first switching circuit. On the other hand, a polarity pulse (for example, a negative pulse) is generated by the capacitor C2 and the second switching circuit. Since the capacitor is charged using the idle time of the transmission / reception sequence, the charged state of the capacitor can always be made good and an appropriate other polarity pulse can be generated. However, the charging action of the capacitor C2 may be exhibited even after the transmission of the other polarity pulse. Even when charging within such a transmission / reception period becomes insufficient, according to the above configuration, the capacitor C2 can be reliably charged using the idle time of the transmission / reception sequence. Therefore, bipolar pulses can be generated using only a power supply having one polarity, and the symmetry of positive and negative pulses can be improved. Since the idle time is used, there is no influence on the ultrasonic image and no influence on the transmission signal.

Desirably, before Symbol control circuit, wherein, when the other polarity pulse is followed by the one polarity pulse is outputted, so that the capacitor C2 is charged in advance. In such a configuration, since charging of the capacitor C2 after transmission of the other polarity pulse is easily affected by transmission of the one polarity pulse, it is highly necessary to employ charging using the above-mentioned idle time.

  Preferably, the second switching circuit includes a switching element Q4 provided between the input side of the capacitor C2 and the power source, and a diode provided between the input side of the capacitor C2 and the switching element Q4. D2, a switching element Q3 provided between the input side of the capacitor C2 and the ground, and a resistor R4 provided between the input side of the capacitor C2 and the power source. Although a bypass path with the resistor R4 inserted is also a charging path in a sense, it is difficult to expect rapid charging because the resistor R4 usually has a large resistance value. On the other hand, if the switching element Q4 is turned on after the transmission of the polarity pulse, a power state can be established by connecting a power source to the input side of the capacitor C2. However, if a one-polarity pulse is generated at that time, the capacitor C2 may not be sufficiently charged. Therefore, it is desirable to adopt the above configuration. In the case where only the pulse of the other polarity is repeatedly transmitted alone, charging using the idle time in the transmission / reception sequence may not be performed if sufficient charging by the ON operation of the switching element Q4 can be expected.

Preferably, the control circuit has a ground connected to the element signal line outside the one polarity pulse transmission period and the element signal line in the one polarity pulse transmission period with respect to the first switching circuit. The first control signal SG1 for connecting the power supply is output, and the ground is connected to the input side of the capacitor C2 during the other polarity pulse output period with respect to the switching element Q3 of the second switching circuit. The second control signal SG2 is output, and the switching element Q4 of the second switching circuit is connected to the input side of the capacitor C2 in the idle time of the transmission / reception sequence, and the other polarity Immediately after the pulse output period, the power supply is connected to the input side of the capacitor C2. Outputting a third control signal SG3 to be. Preferably, the idle time of the transmission / reception sequence is a system setting period after the reception period and before the transmission period. The system setting time is a period in which delay data is set in the digital beam former, and is not transmitted / received.

  According to the present invention, the capacitor for pulse generation can be charged properly. Alternatively, waveform symmetry can be improved when a bipolar pulse is generated using a unipolar power supply.

It is a figure which shows embodiment of the transmission circuit which concerns on this invention. It is a figure which shows the relationship of three control signals. It is a figure which shows the charge period of the capacitor | condenser in a transmission / reception sequence. It is a figure which shows the conventional transmission circuit.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a transmission circuit according to the present invention. This transmission circuit is a circuit provided for each vibration element. However, a part of the configuration may be shared between the plurality of vibration elements. The transmission circuit is provided in the transmission unit of the medical ultrasonic diagnostic apparatus. In addition, the same code | symbol is attached | subjected to the structure similar to the structure shown in FIG.

  In FIG. 1, the transmission circuit 10 includes a transmission drive circuit 12 and a transmission control circuit 14. The transmission drive circuit 12 includes a first switching circuit 200 and a second switching circuit 202. Moreover, it has the capacitor | condenser C2 for a negative pulse production | generation. The input side of the capacitor C2 is a point B, and the output side is a point A (a connection point on the element signal line). The configuration and operation of the first switching circuit 200 are the same as those shown in FIG.

  The second switching circuit 202 includes a switching element Q3 and a switching element Q4. They are composed of FETs. A resistor R4 is provided in the path between the power source (+ HV) and the point B. A resistor R2 is provided in the path between the power supply and the gate of the switching element Q4. Control signal SG1 is applied to switching circuit 200, control signal SG2 is applied to switching element Q3, and control signal SG3 is applied to switching element Q4. The switching element Q3 is turned on during the negative pulse generation period, and connects the point B to the ground. Then, the potential at the point A changes from the ground level to -HV corresponding to the change in the potential at the point B from + HV to the ground level. This causes a negative pulse at point A. The switching element Q4 is turned on only for a certain period after the negative pulse transmission period, and connects the power source to the input side (point B) of the capacitor C2. As a result, the potential at point A is forcibly pulled back to the ground level (point B is pulled back to + HV). However, when a positive pulse is generated following a negative pulse, the potential at point B may rise to a level higher than + HV (eg, +2 HV). In that case, since the diode D2 works, proper charging cannot be performed. Each time transmission is repeated, the charge of the capacitor C2 decreases, the level of the negative pulse falls, and the symmetry of the positive and negative pulses is greatly broken. Therefore, as described below, the charging process of the capacitor C2 is executed in the idle time. Note that the switching element Q4 is in the OFF state except for the period immediately after the negative pulse transmission.

  The above contents will be described in more detail with reference to FIGS. FIG. 2 shows the waveforms of the control signals SG1, SG2, and SG3. When it is desired to transmit a positive pulse, a pulse as indicated by reference numeral 100 is supplied as the control signal SG1. Accordingly, a positive pulse as indicated by reference numeral 102 is generated by the action of the switching circuit, and is supplied to the vibration element. On the other hand, when it is desired to transmit a negative pulse, a pulse indicated by reference numeral 104 is supplied as the control signal SG2, and a pulse indicated by reference numeral 108 is supplied as the control signal SG3 immediately after that in order to quickly recover the potential. The As a result, a rectangular negative pulse is generated as indicated by reference numeral 106. Next, when it is desired to transmit a set of a negative pulse and a positive pulse, a pulse indicated by reference numeral 104 is given as the control signal SG2, and a pulse indicated by reference numeral 108 is given as the control signal SG3 immediately thereafter. As a result, a set of a negative pulse 106 and a positive pulse 102 indicated by reference numeral 103 is generated.

  FIG. 3 shows a transmission / reception sequence. Reference numeral 200 denotes a reception period, 202 denotes a system setting period, and 204 denotes a transmission period. When transmitting a set of a negative pulse and a positive pulse, a pulse indicated by reference numeral 104 is given as the control signal SG2, and immediately after that, a pulse indicated by reference numeral 108 is given as the control signal SG3. At the same time, a pulse denoted by reference numeral 100 is given as the control signal SG1. In such a case, if the potential at point B shown in FIG. 1 rises above + HV, the capacitor C2 cannot be charged by the action of the diode D2. Although it is possible to charge the capacitor C2 by extending the output period of the pulse 108, the ultrasonic image may be affected by switching the switching element Q4 from the on state to the off state during the subsequent reception period 200. There is. Therefore, a charging period 206 is determined within the system setting period 202, and the switching element Q4 is turned on using the control signal SG3 during the period. During the system setting period, there is no influence on the ultrasonic image and no influence on the transmission operation. The charging period 206 may be secured for every system setting period of every cycle, or the charging period 206 may be set every plural number. In the circuit configuration shown in FIG. 1, since it is only necessary to individually supply control signals to the switching elements Q3 and Q4, it is easy to use the popular product package as a transmission circuit.

  As described above, if the capacitor C2 is sufficiently charged in advance using a period that does not affect transmission / reception, problems such as a decrease in the level of the negative pulse and a breakdown of the symmetry of the positive / negative pulse can be prevented. Is possible.

  DESCRIPTION OF SYMBOLS 10 Transmission circuit, 12 Transmission drive circuit, 14 Transmission control circuit, 16 Vibration element.

Claims (5)

A transmission circuit connected to the vibration element via an element signal line,
A first switching circuit for connecting a power source of one polarity to the element signal line in one polarity pulse output period;
A capacitor C2 whose output side is connected to the element signal line;
A second switching circuit for generating a second polarity pulse on the output side of the capacitor C2 by connecting a ground to the input side of the capacitor C2 in a charged state in the other polarity pulse output period;
A control circuit that turns on the switching element Q4 provided between the input side of the capacitor C2 and the power supply using the idle time of the transmission / reception sequence so that the capacitor C2 is charged in advance;
A transmission circuit of an ultrasonic diagnostic apparatus. The transmission circuit according to claim 1,
Before SL control circuit, the other if the polarity pulse followed by the one polarity pulse is outputted, so that the capacitor C2 is charged in advance, the transmission circuit of the ultrasonic diagnostic apparatus characterized by. The transmission circuit according to claim 2, wherein
The second switching circuit includes:
The switching element Q4;
A diode D2 provided between the input side of the capacitor C2 and the switching element Q4;
A switching element Q3 provided between the input side of the capacitor C2 and the ground;
A resistor R4 provided between the input side of the capacitor C2 and the power source;
including,
A transmission circuit for an ultrasonic diagnostic apparatus. The apparatus of claim 3.
The control circuit includes:
A ground is connected to the element signal line outside the one polarity pulse transmission period and the power source is connected to the element signal line during the one polarity pulse transmission period with respect to the first switching circuit. A first control signal SG1 is output,
A second control signal SG2 for connecting the ground to the input side of the capacitor C2 during the other polarity pulse output period to the switching element Q3 of the second switching circuit;
The power source is connected to the input side of the capacitor C2 in the idle time of the transmission / reception sequence with respect to the switching element Q4 of the second switching circuit, and the power source is connected to the input side of the capacitor C2 immediately after the other polarity pulse output period. A third control signal SG3 is output so as to be connected,
A transmission circuit for an ultrasonic diagnostic apparatus. The apparatus according to any one of claims 1 to 4,
The transmission circuit of the ultrasonic diagnostic apparatus, wherein the idle time of the transmission / reception sequence is a system setting period after the reception period and before the transmission period.

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