JP2002065672A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the decrease in scales of two kinds transmitting wave amplification circuits respectively for a pulse wave and for a continuous wave. SOLUTION: An input terminal 1 to which a transmitting wave signal for the pulse wave and a transmitting wave signal for the continuous wave are inputted in a common way, a common amplification circuit 2 connected to the input terminal 1, an amplification circuit 4 for the pulse wave and an amplification circuit 5 for the continuous wave each connected to the output of the common amplification circuit 2, an output terminal 6 comprising a common connection of the outputs each for the amplification circuit for the pulse wave and the amplification circuit for the continuous wave are equipped to construct the amplification circuits allowing to decrease the scale of the circuits by common use of a part of the amplification circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus having a function of switching and driving an ultrasonic vibrator by pulse and continuous wave ultrasonic waves.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus basically applies a voltage to a vibrator made of a piezoelectric material, transmits ultrasonic waves generated by the voltage to a subject, and generates various ultrasonic waves from reflected waves emitted from the subject. This is for extracting important information and knowing the state inside the subject.

Here, as a voltage waveform applied to the vibrator, a pulse wave (PW) method and a continuous wave (CW) method are generally used depending on the purpose of diagnosis. The pulse wave method is used to avoid deterioration of the distance resolution, and is a method of transmitting several waves of relatively large amplitude pulses in one transmission. On the other hand, the continuous wave method is a method of transmitting a burst wave containing many pulses or a continuous wave of small amplitude in order to secure Doppler information in generating a Doppler image or the like and improve sensitivity.

On the other hand, a probe that transmits and receives ultrasonic waves by directly contacting a subject is generally formed by arranging a large number of transducers in a linear or curved shape. Then, a transducer (element) group corresponding to an arbitrary transmission / reception aperture is selected, and a desired ultrasonic beam is formed while sequentially driving the transducers. Therefore, ultrasonic signals are transmitted and received independently of each other to a large number of transducers.

[0005] However, if one ultrasonic transmission / reception circuit is provided for all transducers, an enormous number of electric circuit components, signal cables and the like are required. Therefore, generally, the transmitting and receiving circuits are provided by the number of transducers corresponding to the transmitting and receiving apertures, and the driven transducers are switched by switches to be connected to the transmitting and receiving circuits, thereby reducing the circuit scale and the like.

On the other hand, in an ultrasonic diagnostic apparatus, S / N
There has been a demand for improvement in image quality such as improvement and sensitivity in deep areas, and a system with a large diameter has been developed to respond to this, and the circuit scale of the transmission / reception circuit tends to increase.

[0007]

By the way, in order to provide the functions of both the pulse system and the continuous wave system, since the electrical characteristics of the transmitted and received waves are different, the gain is fixed using an analog amplifier. In the case of the conventional transmission amplifier circuit described above, two types of transmission amplifier circuits for pulse and continuous wave must be provided independently. Therefore, twice as many wave transmitting amplifier circuits as the number of vibrators to be driven are required.
Along with the increase in the diameter, the circuit scale becomes larger and the installation space is increased.

In order to generate ultrasonic waves by driving the vibrator, it is necessary to generate sufficient vibration distortion in the vibrator. For this purpose, it is generally necessary to apply a voltage of about 100 V. Since such a voltage is generated by the transmission amplifier circuit, there is a problem that power consumption is further increased due to an increase in diameter. As a method of reducing the power consumption, it is conceivable to suppress the power consumption by switching the power supply of the transmission amplifier circuit. However, it takes time to switch the voltage of 100 V, which may limit the diagnostic mode. Is not preferred.

Further, the transmission amplifier circuit for pulse and continuous wave is used by switching according to the diagnosis mode, and the switching is generally performed by an analog switch or the like. However, there is a possibility that the output characteristics of the amplifier may be deteriorated due to the influence of the on-resistance of the analog switch, or the transmission waveform may be distorted due to the mixing of switching noise, thereby deteriorating image quality. To avoid this, there is a problem that a dedicated circuit needs to be constructed, which leads to an increase in circuit scale.

An object of the present invention is to reduce the scale of two types of transmission amplifier circuits for pulse waves and continuous waves.

[0011]

In order to solve the above problems, a transmission amplifier circuit according to the present invention comprises an input terminal to which a pulse wave transmission signal and a continuous wave transmission signal are commonly input. A common amplifier circuit connected to the input terminal, a pulse wave amplifier circuit and a continuous wave amplifier circuit respectively connected to the output of the common amplifier circuit, the pulse wave amplifier circuit and the continuous wave amplifier And an output terminal formed by connecting the outputs of the circuits in common.

That is, according to the present invention, the transmission amplifiers for the pulse wave and the continuous wave have at least different amplification characteristics.
The circuit scale of the transmission amplifier circuit was reduced by applying the stage amplification and sharing the preceding amplification circuit.
For example, when the amplification factor of the transmission amplifier for the continuous wave is about 10 times and the amplification factor of the transmission amplifier for the pulse wave is 50 to 60 times, the amplification factor of the common amplification circuit which is the preceding amplification circuit is 1
This can be realized by setting the gain to about 0 times, setting the gain of the pulse wave amplifier circuit, which is the subsequent amplifier circuit, to 5 to 6 times, and the gain of the continuous wave amplifier circuit to about 1 time.

Further, transistors (for example, transistors, for example) are used as amplifying elements of the subsequent-stage pulse wave amplifier circuit and continuous wave amplifier circuit.
When an FET or the like is used, it is preferable to provide a bias circuit for applying a DC bias so that the input signal can operate from a small voltage range. However, in this case, the bias current also flows through the amplifying element of the unused amplifier circuit.
Therefore, it is desirable to provide a control circuit that forcibly turns on and off the amplifying element of the subsequent amplifying circuit based on the mode selection signals for the pulse wave and the continuous wave.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transmission amplifier circuit according to the ultrasonic diagnostic apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows a conceptual configuration diagram of an embodiment of a transmission amplifier circuit, and FIG. 2 shows a block configuration diagram of an ultrasonic diagnostic apparatus to which the transmission amplifier circuit according to the present invention is applied.

As shown in FIG. 2, the ultrasonic diagnostic apparatus includes an ultrasonic probe 11, a transmission processing circuit 12, a transmission amplifier circuit 13, a reception amplifier circuit 14, a phasing processing circuit, Fifteen
, A signal processing circuit 16, an image processing circuit 17, and a display monitor 18. Although not shown, the probe 11 is formed by arranging a number of transducers, and is used in close contact with the surface of the subject. In general, each transducer converts an input pulse wave or continuous wave transmission signal into an ultrasonic wave and emits the ultrasonic wave to the subject, and receives an ultrasonic signal reflected from the inside of the subject to receive an electric signal. It is formed to have a function of converting into a wave signal and outputting it.

The transmission processing circuit 12 converts a transmission signal of a fundamental frequency f ₀ output from an ultrasonic transmitter (not shown) into
The transmission time to a predetermined oscillator is adjusted and output. That is, the transmission waves transmitted to the respective ultrasonic transducers so that the ultrasonic waves emitted from the plurality of transducers arranged in a strip form arrive at one focal point in the subject which is variably set. The signal transmission timing (phase) is controlled. The transmission amplifier circuit 13 amplifies the transmission signal output from the transmission processing circuit 12 and directed to each transducer, and amplifies the probe 1
One corresponding vibrator is supplied. In the present embodiment, the transmission processing circuit 12 and the transmission amplifier circuit 13
Is designed to transmit both a pulse wave (PW) and a continuous wave (CW) according to the selection.

The receiving amplifier circuit 14 has a function of receiving a plurality of received signals output from a plurality of transducers separately from a transmitted signal, and amplifying the received signals. This receiving amplifier circuit 1
From 4, the number of received signals corresponding to the number of transducers is input to the phasing processing circuit 15 as independent received signals. The phasing processing circuit 15 captures the input received signal, and, contrary to the case of the above-described transmission processing circuit 12, a plurality of reflected waves emitted from one focal point in the subject are arranged in a strip shape. In order to eliminate the time lag to reach the vibrator,
The phase of the received signal output from each transducer is delayed and matched, a plurality of matched received signals are added to form a received beam signal, and acoustic characteristic information from one focal point is obtained. It has become. The received signal a output from the phasing processing circuit 15 is input to a signal processing circuit 16 and subjected to signal processing such as filter processing, compression processing, detection processing, enhancement, and Doppler arithmetic processing. Output to 17. The image processing circuit 17 has a function of a digital scan converter (DSC), and converts a received signal into image data and causes the display monitor 18 to draw the image data.

The transmission amplifier circuit 1 in the embodiment of FIG.
As shown in FIG. 1, reference numeral 3 denotes an operational amplifier (OP amplifier), which is a pre-amplifier connected to the input terminal 1, and a post-amplifier 3 connected to the output of the operational amplifier 2. The post-amplifier 3 includes a pulse wave amplification PW amplification unit 4 and a continuous wave amplification CW amplification unit 5 connected to the output of the operational amplifier 2, respectively. The outputs of the PW amplifying unit 4 and the CW amplifying unit 5 are commonly connected to an output terminal 6, so that the amplified transmission signal is supplied to a vibrator (not shown). Also,
A control signal Tcont corresponding to a diagnostic mode selection signal for a pulse wave and a continuous wave is input to the PW amplifying unit 4 and the CW amplifying unit 5, and one of the amplifying elements of the PW amplifying unit 4 and the CW amplifying unit 5 is used. Is turned off.

That is, the amplifier circuits for PW and CW are divided into two stages, the amplifier circuit of the preceding stage is made common, and the amplification characteristics adapted to each are realized by the amplifier circuit of the subsequent stage.
That is, since the PW and the CW have different amplitudes required when performing imaging, amplification is performed in accordance with the respective amplifiers in the subsequent stage. For example, the amplification factor of the transmission amplifier for CW is about 10 times, and the amplification factor of the transmission amplifier for PW is 50 to 6 times.
In the case of 0 times, the amplification factor of the OP amplifier 2 in the former stage is set to about 10 times, the amplification factor of the PW amplification unit 4 in the latter stage is 5 to 6 times,
The amplification factor of the W amplification unit 5 is set to about one. As described above, according to the embodiment of FIG. 1, since the former stage of the two types of transmission amplifier circuits is shared, the circuit scale can be reduced.

Here, FIG. 3 shows an embodiment of a specific circuit configuration of the post-amplifier circuit of FIG. The embodiment of FIG.
1 shows a basic configuration of a transmission amplifier circuit according to the present invention.
As shown in the figure, the PW amplification unit 4 and the CW amplification unit 5 have a similar circuit configuration, and are each formed by a push-pull circuit using an FET (field effect transistor) as an amplification element. That is, a P-type FET 1 and an N-type FET
The two drains are connected to each other and connected to the output terminal 6, and the respective sources are connected to the power supplies + HV1 and -HV1. Also, the gates of FET1 and FET2 are commonly connected, and a resistor R
1 and to the output of the OP amplifier 2 and to the common drain connection point via a resistor R2. However, the circuit constants of these circuit elements are set to different values according to the required amplification characteristics. In particular, the CW amplifier 5
The power supply of the push-pull circuit composed of FET1 and FET2 is set to a voltage different from that of the PW amplifier 4, such as + HV2 and -HV2.

As described above, as shown in FIG. 3, since the PW amplification section 4 and the CW amplification section 5 have similar circuit configurations, the circuit design becomes easy and the OP amplifier 2 in the preceding stage is used.
And the connection is facilitated. Further, since the push-pull circuit is used, it is easy to match the input impedance to the low input impedance of the vibrator. Furthermore, if the transmission amplifier circuit of the present embodiment is formed by matching the input / output pins of a conventional PW amplifier formed by an IC module, the transmission amplifier circuit for both PW / CW is provided by directly replacing the transmission amplifier circuit of the present embodiment. It can be formed in an ultrasonic diagnostic apparatus.

Here, generally, the operation of the FET is determined by the gate
It is determined by the source-to-source voltage and the drain current.
In the case of a push-pull circuit, such as the transmission amplifier circuit shown in FIG. 3, unless a DC bias is applied to the FET, the FET may not operate when the level of the input signal is small, and the output waveform may be distorted. May occur. Therefore, in order to operate the FET even with a small input signal, it is necessary to flow a slight drain current as a bias. It is preferable that the bias current is suppressed to a small value that does not cause waveform distortion in the output, and the influence of heat generation is reduced.

FIG. 4 shows an embodiment of the bias circuit in consideration of such points. As shown in the figure, resistors R13 and R23 are inserted between the sources of FET1 and FET2 and the power supplies + HV and -HV, respectively. Power supply + HV,-
Connect to HV. Then, the constant current source 8 is connected between a connection point between the Zener diode ZD1 and the resistor R14 and a connection point between the Zener diode ZD2 and the resistor R24. Also,
The input signal is input to the gates of FET1 and FET2 via capacitors C11 and C21, respectively.

Here, Zener diodes ZD1, ZD
Assuming that the zener potential of No. 2 is Vz (V), the gate potential of FET1 is fixed at + HV-Vz. The same applies to FET2. Then, the drain current Id is determined to a value that suppresses the above-described power consumption and suppresses the distortion of the output waveform. This Id is set to an optimum value by adjusting the resistors R13 and R23 connected to the source. As a result, the source potential of the FET 1 becomes + HV-R13 · Id. Then, the gate-source voltage Vgs of the FET 1 becomes −Vz + R13 · Id, which is determined independently of the power supply voltage + HV.
That is, since the bias circuit is formed by the Zener diode ZD, the PW amplification unit 4 and the CW amplification unit 5
The same operation is performed regardless of the power supply voltages HV1 and HV2.

In FIG. 3, which of the PW amplifier 4 and the CW amplifier 5 is operated is selectively switched by a control signal Tcont. For example, Tcont is a binary logic signal, CW operation at L (Low), PW at H (High).
Set to action. Then, based on H and L of Tcont,
Any one of the FETs 1 and F of the PW amplifier 4 and the CW amplifier 5
The operation of ET2 is turned on and off. Specifically, it can be realized by the switching control circuit shown in FIG. That is, the bipolar transistor Q1 is inserted and connected between the gate of the FET1 and the power supply + HV, Tcont is input to the base via the resistor R15, and the base is connected to the power supply + HV via the resistor R16. here,
The H level of Tcont is set to + HV, and the L level is + H
It is assumed that V-α is set. The figure shows FET1
Although only a switching control circuit is shown for
The same applies to FET2.

With this configuration, when Tcont is H, a potential of + HV is applied to the base of the transistor Q1, and the voltage between the base and the emitter of the transistor Q1 is equal, so that the transistor Q1 is turned off. .
As a result, as in the case where the transistor Q1 is not provided in the FET1, a drain current flows by the bias circuit of FIG. 4 and the FET1 is turned on. That is, when Tcont is H, FET
1 turns on, and the PW amplifying unit 4 is selected and operated. On the other hand, when Tcont is L, +
The potential of HV-α is applied. Here, α is the transistor Q
By setting 1 to a value enough to turn on, the voltage between the base and the emitter of transistor Q1 becomes α, and transistor Q1 turns on. That is, an emitter current flows through the transistor Q1, and the gate potential of the FET 1 becomes substantially equal to + HV. As a result, the gate-source voltage required for the operation of the FET 1 cannot be sufficiently obtained, and the FET 1 is turned off. That is, when Tcont is L, the FET 1 is turned off, and the operation of the PW amplifier 4 stops. In the case of the CW amplifying unit 5, the switching circuit can be realized by creating a state opposite to the PW amplifying unit 4 with respect to Tcont.

As described above, according to the switching control circuit shown in FIG. 5, according to the Tcont output from the control means (not shown) of the ultrasonic diagnostic apparatus based on the selection signal of the PW mode or the CW mode. , PW amplifier 4 and CW
Switching of the amplification unit 5 can be performed. Moreover,
According to the present embodiment, since the FET is turned off, the bias current described with reference to FIG. 4 is stopped, so that unnecessary current consumption can be reduced.

In particular, according to the embodiment shown in FIG. 3, since the input and output terminals of the PW amplifying unit 4 and the CW amplifying unit 5 are connected in common, the problem of crosstalk between them is bothersome. In this regard,
Since the switching control circuit of FIG. 5 completely turns off the FET, there is no problem of crosstalk.
That is, the gate potential of the inactive FET is
No matter what voltage is applied to the gate, the transistor Q1 will not lower the source potential in the case of P-type and will not be higher than the source potential in the case of the N-type due to the short-circuit effect of the transistor Q1. Is completely off.

[0029]

As described above, according to the present invention, the scale of the two types of transmission amplifier circuits for pulse waves and continuous waves can be reduced.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an embodiment of a transmission amplifier circuit according to a characteristic portion of the present invention.

FIG. 2 is a block diagram of an embodiment of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 3 is a specific circuit diagram of an embodiment of a transmission amplifier circuit according to a characteristic portion of the present invention.

FIG. 4 is a circuit diagram of a bias circuit according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a switching circuit according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 input terminal 2 operational amplifier 3 post-amplifier 4 PW amplifier 5 CW amplifier 6 output terminal 11 probe 12 transmission processing circuit 13 transmission amplifier circuit 14 reception amplifier circuit 15 phasing processing circuit 16 signal processing circuit 17 image processing Circuit 18 Display monitor

Claims (1)

[Claims] An ultrasonic probe for transmitting and receiving an ultrasonic wave, a transmission processing circuit for performing a focus process of a pulse wave or a continuous wave transmission signal transmitted to the ultrasonic probe, and the transmission process A transmission amplifier circuit that amplifies a pulse wave or continuous wave transmission signal output from the circuit and supplies the amplified signal to the ultrasonic probe, and performs a focus process on a reception signal output from the ultrasonic probe. An ultrasonic diagnostic apparatus comprising: a phasing circuit for performing pulse wave transmission; and an image processing means for generating an image based on a received signal output from the phasing circuit. An input terminal to which the wave signal and the transmission signal for the continuous wave are input in common, a common amplifier circuit connected to the input terminal, and a pulse wave amplifier circuit connected to the output of the common amplifier circuit, and A continuous wave amplifier circuit, the pulse wave amplifier circuit and the Ultrasonic diagnostic apparatus characterized by comprising an output terminal formed by commonly connecting the output of the amplifier circuit for connection waves.