JPH0834648B2 - Transceiver circuit in ultrasonic device - Google Patents

Description

Description: [Industrial field of use] The present invention relates to a transmission / reception circuit in an ultrasonic device.

[Prior Art] An ultrasonic wave transmitting / receiving circuit configuration used in a conventional ultrasonic diagnostic apparatus is disclosed in, for example, Japanese Utility Model Laid-Open No. 56-73809 and Japanese Patent Laid-Open No. 58-69.
536, 57-67711, 59-80746, etc., except for the switching element and other details, the circuit configuration of the main part is shown in FIG. Second
In the figure, 10 is a transducer, 20 is a pulse input, 21 is a front driver, 30 is a DC power supply, 31 is a driver element, 34, 35
Is a resistor and capacitor of a driver circuit, 40 is an inductor, 41 is a damping resistor, 50 is a cable, 61 is a receiving amplifier, and 60 is a receiving amplified signal. In the drive of the transducer in the conventional device, the drive element 31 is turned off, the voltage of the power supply 30 is charged into the capacitor 35 through the resistors 34 and 41, and the inductor 40, and the drive element 31 is turned on for a time corresponding to a predetermined pulse width. This is done by discharging the electric charge of the capacitor 35 toward the transducer 10. Here, in the conventional device, the number of transmitted pulses emitted at one time is one to several, and the off (non-drive) period is, for example, 1000 times as compared with the on (drive) period of the drive element 31.
The charge of the capacitor 35 discharged at the time of driving is sufficiently replenished during the non-driving period because it is sufficiently long, such as twice or more, so that a stable driving function is achieved with each ejection.

[Problems to be Solved by the Invention] Although the above-mentioned conventional technique is sufficient for pulse drive of one to several shots, when a larger number of pulse waves are emitted (emission of burst wave) ) Or when continuously outputting pulses, there is a problem that the balance of charge and discharge to the capacitor 35 cannot be maintained, the amplitude of the output pulse gradually decreases, and pulses of the same shape cannot always be transmitted.

Therefore, an object of the present invention is to provide a transmission / reception circuit that always outputs a pulse having the same condition, that is, the same waveform, and receives an ultrasonic echo signal even in the case of multi-wave or continuous pulse drive. .

[Means for Solving the Problems] In order to achieve the above object, in the present invention, the drive power source is directly connected to the conventional device without using the charging charge of the capacitor 35.
Take from DC power supply 30. That is, the switching element 31 that is turned on / off according to the drive signal is provided between the power source 30 and the transducer 10. The inductor 40, the damping resistor 41, and the like in the conventional device do not change, and the function and effect thereof do not change.

[Operation] A switching element is arranged in series between the DC power supply and the transducer, the above switch is turned on / off according to an input pulse signal, and a pulse voltage is applied to the transducer. Even in this case, the same drive condition (waveform) is always maintained, and an arbitrary number of drives from single-pulse drive to continuous pulse drive becomes possible.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. 10 is a transducer, 20 is a pulse input signal, 21 is a front driver, 22 is a drive signal capacitor, 30 is a DC power supply,
31 is a drive (switch) element, 32 is a capacitor for stabilizing the voltage of the DC power supply 30, 33 is a bias resistance of the driver 31, 40 is an inductor, 41 is a dampening resistor, 42 is a diode, 50 is a cable, and 62 is a receiving wave. Load resistance, 61 is a wave receiving amplifier, and 60 is a wave receiving amplified output signal. The voltage of the DC power supply 30 charges the capacitor 32. When there is no signal in the drive signal 20, the output voltage of the front driver 21 keeps a certain running value, so that the driver 31 (enhancement type FET
The gate potential of the element) becomes the same as that of the power supply 30, and therefore the driver 31 is turned off. Here, when the drive signal 20 causes the output potential of the predriver 21 to change in a pulsed manner by a certain constant value, this potential displacement is transmitted to the gate of the driver 31 via the capacitor 22. If the driver element is an N-channel FET, a negative voltage is used as the power supply 30, and if the output of the front driver has a positive voltage change polarity, the driver 31
Turns on, thus connecting transducer 10 and power supply 30 through driver 31. At the same time, the inductor
Current also flows through 40. When the output of the pre-driver continues to change in the opposite direction, the driver 31 turns off, but the counter electromotive force due to the current flowing in the inductor 40 causes the transducer 31 to turn off.
A voltage having the opposite polarity to the above is applied to 10. Here, a parallel resonance circuit is formed by the capacitance of the inductor 40 and the capacitance of the transducer 10 and the cable 50, and the driver 31 turns on.
The vibration according to the off state continues due to the resonance characteristic. If this characteristic is not desirable such as during single pulse drive, a resistor 41 is inserted in parallel with the inductor 40 as a damping resistor. The diode 42 blocks the drive current from the power source 30 and serves as the damping resistor so that only the current due to the counter electromotive force of the inductor is passed to reduce the loss. When the driver element 31 is a P-channel element, the power source 30 has a positive voltage, and the diode 42 has a direction opposite to that shown in FIG. The relationship between the polarity of the output pulse of the front driver 21 and the on / off operation of the driver 31 is
The polarity is opposite to that of the channel element.

The transducer 10 receives ultrasonic echo signals as well as ultrasonic waves. That is, the echo is converted into an electric signal by the transducer 10, the signal voltage across the load resistor 62 is amplified by the receiving amplifier 61, and the output 60 is signal-processed to achieve the function as a diagnostic device. Here, since the echo signal is very small and is usually less than or equal to the threshold value of the diode 42 in the forward direction, the load resistance during reception is 62
Will only be. Therefore, the damping condition at the time of wave transmission and the load resistance condition at the time of wave reception can be selected independently.

EFFECTS OF THE INVENTION According to the present invention, a transducer is driven with an arbitrary number of pulses, an ultrasonic pulse is transmitted, and an ultrasonic echo signal is received, from a single pulse to a large number of waves to a continuous pulse. It is possible to obtain a transmission / reception circuit capable of performing the above-mentioned drive pulse waves under the same condition, that is, having the same waveform.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a wave transmission / reception circuit of an ultrasonic device showing an embodiment of the present invention, and FIG. 2 is a circuit configuration diagram showing a main part of a wave transmission / reception circuit in a conventional device. 10 …… Transducer, 20 …… Drive signal, 21 ……
Front driver, 30 …… DC power supply, 31 …… Driver element,
40 ... Inductor, 41 ... Damping resistance, 50 ... Cable, 61 ... Receiving amplifier

Claims (1)

[Claims] 1. A transducer for transmitting an ultrasonic pulse to receive an ultrasonic echo signal, an inductor, a damping resistor, and a load resistor for receiving the wave are connected in parallel, a first terminal and a ground. And a DC power supply, and the switching operation is controlled according to the drive signal as a pulse voltage driver for applying a voltage from the DC power supply to the transducer and the inductor. A field effect transistor is provided between the DC power supply and the first terminal of the parallel circuit, and the transmission / reception in the ultrasonic device for transmitting the ultrasonic pulse to receive the ultrasonic echo signal is performed. A circuit, a diode is connected between the damping resistor and a second terminal, and a receiving amplifier circuit is connected to a point on the first terminal side of the load resistor. , Wave transceiver circuit in the ultrasonic apparatus characterized by transmitting and receiving waves of the ultrasonic pulses.