JPH0614935B2 - Transceiver circuit for ultrasonic diagnostic equipment - Google Patents

Description

The present invention relates to a transmission / reception circuit for an ultrasonic diagnostic apparatus, and in particular, a tomographic image signal Doppler shift signal is extracted from a reflection echo from the inside of a subject tomographic image inside the subject. The present invention relates to a transmission / reception circuit for an ultrasonic diagnostic apparatus for displaying both a motion state and a motion state on a screen.

[Prior Art] A reflector that moves while emitting a pulsed ultrasonic beam or the like into a subject such as a living body to display a tomographic image as an image,
For example, an ultrasonic diagnostic apparatus that displays the state of cardiac blood flow is well known. The tomographic image is obtained from the attenuation distribution of the reflection echo, and the motion state is obtained by detecting the Doppler effect received by the reflection echo as a frequency shift of the ultrasonic carrier frequency.

FIG. 4 shows a conventional transmission / reception circuit in which the Doppler shift signal (Doppler signal) is satisfactorily taken out in such an ultrasonic diagnostic apparatus. The transmission circuit outputs an ultrasonic transmission signal. A transducer 12 that generates an ultrasonic wave is connected to 10. The transmission circuit 10 outputs an ultrasonic wave excitation signal formed at a constant repetition cycle as a pulse signal to the vibrator 12 via the cable 14, and by driving the vibrator 12 with this pulse signal, Ultrasonic waves are radiated into the subject at regular intervals.

Further, a receiving circuit 16 is connected to the vibrator 12, and a Doppler signal inductance coil 18 is connected in parallel between the vibrator 12 and the receiving circuit 16. The inductance coil 18 is provided to detect a received signal in a narrow band, and the Doppler signal input to the vibrator 12 is received in the narrow band with high sensitivity, whereby the motion information can be excellently obtained. Images can be displayed.
In an ultrasonic diagnostic apparatus that displays a tomographic image and a Doppler image at the same time, in general, in order to ensure the accuracy of Doppler information, the transmission and reception of the tomographic image is performed once in each direction, and then the Doppler image is transmitted. Image transmission / reception is performed multiple times (for example, 8 to
10 times). Then, such transmission and reception is performed for each direction.

[Problems to be Solved by the Invention] However, the tomographic image signal received as the morphological information in the subject by the transducer 12 needs to receive the signal in a wide band in order to improve the resolution. The Doppler shift signal for displaying the image has a problem that it is necessary to receive the signal in a narrow band because priority is given to the sensitivity, and conventionally, there is a problem that some information must be sacrificed.

That is, the Doppler shift signal is a frequency shift signal of a carrier frequency (ultrasonic wave frequency) that appears as a Doppler effect, and it is preferable to receive a signal in a specified narrow range near a predetermined carrier frequency with high sensitivity.

Therefore, in the conventional apparatus which simultaneously displays the motion state as an image, the inductance coil 18 for the Doppler signal is provided to receive the narrow band signal, but on the other hand, the resolution of the tomographic image is lowered. However, there is a problem in image quality in the diagnosis that attaches importance to the tomographic image.

Also, paying attention to such a point, the inductance coil 1
It is also practiced to selectively switch 8 so that it is used only when making a diagnosis that emphasizes the display of the exercise state. However, since this switching is performed by a switch such as a manual switch, it is preferable to display the tomographic image and the motion state separately by shifting them in time, but when displaying both images at the same time, the maximum speed is 250 μsec. Since the switching is performed, the switching of the Doppler signal coil 18 cannot be performed according to the scanning switching speed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems, and an object thereof is to provide a transmission / reception circuit for an ultrasonic diagnostic apparatus capable of displaying both a tomographic image and a motion state in an excellent state. To do.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention transmits an ultrasonic wave into a subject by a transducer, and a tomographic image signal and a Doppler shift signal from a reflection echo in the subject. In the transmission / reception circuit for the ultrasonic diagnostic apparatus for receiving the information and displaying the in-subject information as an image,
An inductance coil for a Doppler signal for receiving a Doppler shift signal in a narrow band connected in parallel between the vibrator and the receiving circuit, and a low resistance switching element connected in series with the inductance coil A diode and a switch control circuit that controls the on / off switching of this diode at high speed are provided, and the band is always wide during transmission, and the tomographic image signal at reception is wide band and the Doppler shift signal is narrow band at high speed. It is characterized in that it can be selectively received by switching.

[Operation] According to the above configuration, the switch control circuit quickly switches on / off of the diode, and the connection of the inductance coil to the circuit is switched based on the control signal.

That is, when transmitting, the inductance coil is not connected and always has a wide band, when receiving the tomographic image signal, the inductance coil is not connected, and when receiving the Doppler signal, the inductance coil is connected, and The image signal can be received in a wide band and the Doppler signal can be received in a narrow band.

Further, in this case, since the switch control circuit operates at high speed, the tomographic image signal and the Doppler signal can be received in real time.

It is also possible to use a transistor or the like instead of the switching element and the switch control circuit, and control the switching of the inductance coil to the receiving circuit by the transistor without using the switch control circuit. However, in the case of this transistor or the like, since the resistance of the transistor itself is high, the Q value of the circuit is lowered, which makes it meaningless to connect the inductance coil.
A low resistance diode is used.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the main configuration of a transmission / reception circuit for an ultrasonic diagnostic apparatus according to the present invention, and members from the transmission circuit 10 to the inductance coil 18 for Doppler signals are the same as those of the conventional one.

A feature of the present invention is that the connection of the inductance coil 18 to the receiving circuit can be switched at high speed between the reception of the tomographic image signal and the reception of the Doppler signal. And a switch control circuit 22.

That is, the switching element 20 is connected in series to the inductance coil 18 that is connected in parallel between the vibrator 12 and the receiving circuit 16. In the embodiment, a diode is used as the switching element 20, and the anode terminal has an inductance. It is connected to the coil 18. As the switching element 20, it is necessary to use one having a low resistance in order to keep the Q value of the circuit high, and a diode is optimal in this sense.

The switch control circuit 22 for controlling the switching element 20 at high speed is provided with the switching element 20.
On the other hand, a capacitor 24 is connected in series with the switching element 20 and in parallel with the switch control circuit 22 in order to prevent the current from leaking into the other system.

The switch control circuit 22 includes two transistors T
_r1 and T _r2 are connected in series via resistors _r1 and _r2 , a voltage of 5 V is applied to both ends, and a voltage is taken out from the intermediate point (terminal Z) of the two transistors T _r1 and T _r2. To do.

According to this, when the transistor T _r1 is turned on and the transistor T _r2 is turned off by supplying the switching timing signal from the terminal C, the voltage of 5 V at the B terminal is applied, so that the voltage is applied via the transistor T _r1 . As a result, a voltage signal of 5V is output from the intermediate terminal Z. On the contrary, when the transistor T _r1 is turned off and the transistor T _r2 is turned on,
Since the transistor _Tr2 is connected to the ground side, the voltage signal of 0 V is output from the intermediate terminal Z.

The switching speed of the switch control circuit 22 is determined by the time constant of the circuit. In this case, the time constant is about 3Ω when the resistance obtained by adding the internal resistance of the transistor and the resistance r ₁ is about 3Ω. Since there is, it becomes about 0.03 μsec. Therefore, the switching control signal that operates at high speed and changes from 0 V to 5 V can be supplied to the switching element 20, and the switching of the speed of about 20 μsec as described above can be sufficiently dealt with.

The embodiment has the configuration described above, and its operation will be described below.

In FIG. 1, a transmission pulse signal is supplied from a transmission circuit 10 to a vibrator 12, and an ultrasonic pulse is output from the vibrator 12 to a subject according to the transmission pulse.
On the other hand, the transducer 12 receives a reflection echo reflected from the inside of the subject to detect a tomographic image signal and a Doppler signal from the inside of the subject.

In this case, the ground level (0V) is set as the voltage V ₁ between both ends of the vibrator 12, that is, between the X terminal and the Y terminal in the figure.
On the other hand, a voltage corresponding to the forward voltage drop V _F of the switching element 20 formed of a diode is given by the receiving circuit 16.

Then, on the cathode side of the switching element 20,
As shown in FIG. 2, the switch control circuits 22 to 0
A switching control signal that changes from V to 5 V is output, so that the connection of the inductance coil 18 to the circuit is switched.

That is, in the switching control signal of FIG. 2, the switch control circuit 22 which is the cathode side of the switching element 20.
When the voltage V ₂ of the Z terminal on the side becomes 0 V, the potential on the anode side becomes higher than that on the cathode side by V _F, and the switching element 20 becomes conductive (ON). Therefore, the inductance coil 18 is connected in parallel with the vibrator 12, thereby forming a resonance circuit.

On the other hand, the voltage V _{2 at} the Z terminal on the switch control circuit 22 side is 5
At V, the potential on the cathode side becomes V _F on the anode side.
Since the voltage becomes higher than (X terminal voltage V ₁ ), the reverse voltage is applied to the switching element 20 to bring it into a non-conducting state (OFF), whereby the inductance coil 18 becomes unconnected.

In this way, the switching element 20 is turned on / off by the control signal from the switch control circuit 22, and this on / off operation is performed at high speed, so that the selective switching connection of the inductance coil 18 is performed at high speed. Then, the tomographic image signal is transmitted when the inductance coil 18 is not connected, and the Doppler signal is transmitted to the inductance coil 1.
8 will be received in the connected state.

The capacitor 24 is connected to the circuit simultaneously with the inductance coil 18 when receiving the Doppler signal, and the capacitor 24 can prevent the high frequency from leaking into another system.

In the embodiment, a diode is used as the switching element 2, but since the diode has a small resistance component, the Q value of the circuit can be maintained at a good value, and the Doppler signal can be received in a narrow band. There is an advantage that it becomes possible. Therefore, in the present invention, the FET is used instead of the diode.
It is possible to use a transistor such as, but in this case, it is necessary to use a transistor having a low resistance value.

Further, as described above, according to the present invention, the switching element 2
Since the reverse voltage of 0 may be a low voltage, it is possible to satisfactorily switch the connection of the inductance coil 18 by a control signal of a low voltage. Further, with such a configuration, as a switching control circuit including the switch control circuit 22, A simple structure can be achieved.

In this way, the inductance coil 1 during reception
Although the selective connection of 8 allows a good image signal to be received, this switching operation does not cause any problems during transmission.

That is, the transmission pulse is a signal having a change from the voltage V _F to −V ₃ as shown in FIG. ₃ , but it is unnecessary because the inductance coil 18 is conventionally connected even at the time of transmission. There was a problem that it caused various vibrations. However, in the present invention, the switching element 20 is rendered non-conductive with respect to the transmission pulse, which is equivalent to the case where the inductance coil 18 is not connected during transmission. Therefore, the presence of the inductance coil 18 does not cause an unnecessary tailing state in the transmission signal.

[Effects of the Invention] As described above, according to the present invention, the inductance coil for the Doppler signal is selectively switched to be connected to the transmission circuit and the reception circuit. When receiving a signal, both the tomographic image signal and the Doppler signal can be satisfactorily received without being affected by the inductance coil.

Further, since the switching is performed at a higher speed than the switch control circuit, the tomographic image signal and the Doppler signal can be switched at a high rate, and the real-time information of both can be displayed at the same time.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a schematic configuration of a transmission / reception circuit for an ultrasonic diagnostic apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a switching control super signal output from a switch control circuit of the present invention. FIG. 3 is a diagram showing a transmission signal output from the transmission circuit, and FIG. 4 is a circuit block diagram showing a schematic configuration of a conventional transmission / reception circuit. 10 ... Transmission circuit 12 ... Oscillator 16 ... Reception circuit 18 ... Inductance coil 20 ... Switching element 22 ... Switch control circuit.

Claims (1)

[Claims] 1. An ultrasonic wave for transmitting ultrasonic waves into a subject by a transducer, receiving a tomographic image signal and a Doppler shift signal from a reflection echo inside the subject, and displaying the in-subject information as an image. In a transceiver circuit for a diagnostic device, an inductance coil for a Doppler signal, which is connected in parallel between the oscillator and a receiving circuit to receive a Doppler shift signal in a narrow band, and is connected in series with the inductance coil. A diode as a low-resistance switching element, and a switch control circuit that controls switching on / off of this diode at high speed,
The transmission / reception for ultrasonic diagnostic equipment is characterized in that a wide band is always provided at the time of transmission, the tomographic image signal at the time of reception is wide band, and the Doppler shift signal is switched and selected at high speed in a narrow band. circuit.