JPH0426416A - Signal transmission circuit of ultrasonic diagnostic device - Google Patents

Abstract

PURPOSE:To obtain the signal transmission circuit of the ultrasonic diagnostic device which does not generate polarization and can operate on higher frequencies by constituting the device of a power source supply section and a driving circuit section, a delay circuit section, and a differential circuit section. CONSTITUTION:A switch SW1 turns on and the potential at the point (a) rises sharply to the level of a voltage VH with transition response and gradually executes an electric discharge when a trigger input signal Si is applied. The trigger input signal Si is applied to a switch SW2 with the delay by as much as the tau time by a delay circuit 3 and, therefore, the switch SW2 is turned on with the delay by tau from the switch SW1. The charge of a capacitor C1 is rapidly discharged through the switch SW1 and the switch SW2 and the potential at the point (a) rises sharply up to a GND level when the switch SW2 turns on. Consequently, the point (a) is the rectangular pulse of a high voltage. The rectangular pulse at the point (d) is differentiated by a differential circuit 4 and, therefore, the waveform at the point (b) is the pulse waveform of positive and negative directions up to +VH to about -VH as shown by (b) of Fig. 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a high-output, high-frequency transmitting circuit for an ultrasonic diagnostic apparatus.

(B) Prior Art A transmission circuit of a conventional ultrasonic diagnostic apparatus is shown in FIG. 6 (Japanese Unexamined Patent Publication No. 117533/1983).This transmission circuit includes an output transistor Q. The drive circuit section 60 is connected to first and second base-grounded amplifier circuits consisting of NPN (NPN) transistors Q, , Q, each having a resistor R, , R, connected to the input side, and an output terminal connected to the second base. It consists of a collector grounded amplifier circuit consisting of an NPN transistor Qc connected to the output terminal of the grounded amplifier circuit and the gate of the output transistor Q b x. This transmitter circuit has an output transistor Q. MOS-FET is used for the power supply section,
High output and high frequency output was obtained through 0N10FF control using a signal from the drive circuit section.

(c) Problems to be Solved by the Invention The transmission circuit of the conventional ultrasonic diagnostic device described above has one stage of output transistors and is configured to turn a single power supply into 0N10FF, so the output is only a trapezoidal pulse in the direction of one power supply. I can't get it. Therefore, the frequency characteristics of the output have a wide range, and there is a possibility that polarization may occur when the vibrator is dried. Furthermore, there is a problem in that there is a limit to increasing the frequency due to the gate delay of the output transistor.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a transmitting circuit for an ultrasonic diagnostic apparatus that does not cause polarization and can realize a high frequency.

(d) Means and Effects for Solving the Problems The transmission circuit of the ultrasonic diagnostic apparatus of the present invention includes a power supply unit that includes a power supply capacitor that charges voltage from a power supply and an overcurrent control unit, and a power supply unit that a drive circuit section consisting of a first transistor that supplies the accumulated charge of the storage capacitor to the load and a second transistor that discharges the accumulated charge; and a delay circuit section that shifts the control timing of the first and second transistors. and a differentiation circuit section that differentiates the output of the drive circuit section and supplies it to the load.

In this transmission circuit, when no trigger input signal is input, charge is stored in the power supply capacitor up to the power supply voltage. When a trigger input signal is applied,
The first transistor turns on, and the output of the drive circuit rises steeply to the power supply voltage. On the other hand, after the delay time caused by the delay circuit, the second transistor turns ON, the charge in the power supply capacitor is discharged via the first and second transistors, and the output of the drive circuit section sharply drops to the GND level. Fall down. In other words, the drive circuit section outputs a signal with a pulse width corresponding to the delay time. This pulse signal is differentiated by a differentiating circuit section, and pulses of both positive and negative polarities are output to the load.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 is a circuit diagram showing the basic configuration of a transmitting circuit according to the present invention. In the same figure, +■o power supply (100 to 200
A power supply unit 1 is connected to V), which includes a resistor R for overcurrent limiting, a coil, and a power supply capacitor C3 for charging the power supply voltage. Furthermore, the power supply section 1
and GND between the first switch SWl and the second switch S
A drive circuit section 2 made of Wt is connected. Although the switches SWl and SW2 are shown in principle as contact diagrams here, transistors or the like are actually used.

The switch SWl of the drive circuit section 2 is turned on by the input signal S, and the input signal S is applied to the switch SW2 after being delayed by the delay circuit 3, and the switch SW2 is turned on. The output of the drive circuit section 2 is supplied to the load RI- through a differentiating circuit 4 consisting of a resistor R2 and a capacitor C2.

Next, the operation of the transmitter circuit shown in FIG. 1 will be explained with reference to the signal waveform diagram shown in FIG.

Before the trigger input signal S is applied, the switch SW
+ and S W z are both in the OFF state, and the power supply ■8 is connected to the capacitor C1 through the coil LI and resistor R1.
More charges are being charged and accumulated, reaching a voltage level of 8. Eventually, when a trigger input signal S, is applied,
When the switch SW1 is turned on, the potential at point a rises sharply to the level of voltage ②a due to a transient response, and then gradually discharges (see a in FIG. 2). In addition, the trigger input signal S
i is delayed by the delay circuit 3 by the time τ and then the switch SW
2, the switch SW2 is added to the switch SWl
It is turned on with a delay of τ. When switch SW2 is turned on, the charge in capacitor C5 is transferred to switches sw, , SW
2, a strong discharge occurs, and the potential at point a drops sharply to the GND level. As a result, point a becomes a high voltage rectangular wave pulse.

Since the rectangular wave pulse at point a is differentiated by the differentiating circuit 4,
The waveform at point b ranges from +VH to approximately -V, as shown in Fig. 2b.
The pulse waveform is up to H in the positive and negative directions.

FIG. 3 shows a specific example transmitting circuit. 1st
The same reference numerals as in the figures indicate the same parts. Here, the transistor Q corresponds to the switch SWI in FIG.
, is. Further, the resistor R1, diode DI% capacitor C5 constitutes a bias circuit for the transistor Q.

The transistor Q corresponds to the switch SW2 in FIG. Resistor R1 is transistor Q.

The resistor R4 connected between the transistor Q and 92 is an overcurrent protection resistor for the transistor Qt.

The transistor Q3 corresponds to the delay circuit 3 in FIG.
, capacitors C4 and C%, diode D2, and variable resistor VR, which also serves as a driver for transistor Q2 in this circuit example.

In addition, in FIG. 3, the current booster 5 provided at the input section is for driving the gate capacitance of transistors Q, , Q, and specific circuit examples thereof are shown in FIGS. 4 and 5. ing.

In the circuit of FIG. 3, the delay time τ is the transistor Q,
The time constant (Cs + CI+) is determined by the gate input capacitance C1, the capacitor C3, and the variable resistor VR. Therefore, by changing the resistance value of the variable resistor VR, the delay time τ can be changed and the output frequency can be changed.

In addition, as the delay circuit in Fig. 3, a capacitor C and a resistor R are used.
Although an example of the circuit has been shown, it is also possible to configure a delay circuit using a CR using a variable capacitance diode, or a delay circuit using a delay line.

(F) Effects of the Invention According to the present invention, since the power supply section consisting of the current limiting section and the power supply capacitor is provided, the first and second transistors for power supply and discharge of the output can be ONL at the same time. , no excessive current will flow. Furthermore, since the first transistor for power feeding and the second transistor for discharging are independent, there is no limit to increasing the frequency due to gate delay of the transistor. Further, frequency adjustment can be easily performed by adjusting the control timing of the first and second transistors. Furthermore, since the drive output is output through a differentiating circuit, it becomes a pulse output in the positive and negative directions, which has the advantage of being less likely to cause polarization of the vibrator.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing the basic configuration of the transmitting circuit of the present invention, Fig. 2 is a waveform time chart for explaining the operation of the transmitting circuit, and Fig. 3 is a concrete diagram of the transmitting circuit according to the embodiment. 4 and 5 are circuit connection diagrams showing specific examples of the current booster used in the transmitting circuit of the same embodiment.
The figure is a circuit diagram of a transmitting circuit of a conventional ultrasonic diagnostic apparatus. 1: source supply section, 2: ° drive circuit section, 3: delay circuit section, 4: differentiation circuit section, C+: ii source supply capacitor, R+: iti current limiting resistor, Ql: first transistor, Q2: Second transistor. Patent applicant OMRON Co., Ltd. agent
Patent Attorney Shigeru Nakamura

Claims (1)

[Claims] (1) In a transmitting circuit of an ultrasonic diagnostic apparatus that sends out high-voltage pulses in response to a predetermined trigger input signal, a power supply section consisting of a power supply capacitor that charges voltage from the power supply and an overcurrent control section; a drive circuit section consisting of a first transistor that supplies the accumulated charge of the supply capacitor to the load and a second transistor that discharges the accumulated charge; and a delay circuit that shifts the control timing of the first and second transistors. A transmitting circuit for an ultrasonic diagnostic apparatus, comprising: a differential circuit section that differentiates the output of the drive circuit section and supplies the differentiated output to a load.