JPS63209636A - Transmission circuit of ultrasonic system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has the functions of both an ultrasonic continuous wave Doppler device and an ultrasonic device that uses ultrasonic pulses, and uses high-frequency waves to drive an ultrasonic probe. The present invention relates to a transmitter circuit for an ultrasound system that uses a transmitter driver for power amplifying signals for both functions.

(Prior art) A medical ultrasound system includes an ultrasound imaging device that irradiates ultrasonic pulses into a subject and obtains images such as tomograms based on reflected waves from the subject to make a diagnosis, and a subject. IB? measures the frequency shift of the reflected wave from a moving object within the body, detects the movement velocity of the component in the ultrasound beam direction of the moving object, and evaluates the dynamic function of the subject. :There is a 1st wave door alarm device. Ultrasonic Doppler equipment is a device that irradiates continuous waves into the subject's body and measures the speed of a moving object from the frequency shift of the reflected waves, but since the irradiated ultrasound is a continuous wave, it does not have distance resolution and is difficult to receive. The location of the source of the reflected signal cannot be known.

In order to know the position, an image is displayed using ultrasound imaging s'a and the position is confirmed. Therefore, there is a need for an ultrasound system that has both the functions of an ultrasound Doppler device and an ultrasound imaging 5A device.

In dual-function ultrasound systems, it is advantageous to use the same transmit driver both when transmitting continuous waves and when transmitting pulses or burst waves. This wave transmission driver amplifies the power of an input signal through a switching operation, and supplies an output high-frequency signal to an ultrasonic probe.

(Problem that the invention attempts to solve) The waveform of the signal that is supplied to the ultrasound probe after the transmission driver amplifies the power of the high-frequency signal through a switching operation is a square wave, whether it is a continuous wave high-frequency signal or a pulsed wave high-frequency signal. It has become. Square waves contain odd-order harmonics, so if you try to use the same ultrasonic imaging probe for ultrasound Doppler method and 8-mode imaging method, continuous wave Doppler method In this case, this harmonic, especially the third harmonic, causes problems.

(1) Since the receiving circuit of the imaging device has a wide band, 2
The frequency band ~10M1-1z can be evenly received. Therefore, when transmitting continuous waves in the frequency band of 2 to 3.5 MHz, the receiving circuit can also satisfactorily receive the frequency band of 6 to 10 MHz, and no measures are taken to reduce the sensitivity of that frequency. When transmitting while including the third harmonic, the higher the frequency, the stronger the crosstalk between the transmitter and the receiver, and the third harmonic leaks from the transmitting circuit to the receiving circuit, resulting in crosstalk. In general, receiving circuits for imaging devices include an equalizer or peaking circuit to compensate for the decrease in gain in the high frequency range, so the dynamic range is narrow and is saturated by the crosstalk of this third harmonic. Put it away.

(2) In the balanced demodulator of the receiving circuit, the reference carrier has a high conversion gain, can accurately perform a 90a phase shift, and can be made with a logic circuit that does not require switching even when the frequency changes. If a square wave with and cause noise. In particular, if the third all wave is selectively modulated with hum or the like, it will be demodulated and the hum will be mixed into the Doppler signal.

The present invention has been made in view of the above points, and its object is to transmit a continuous wave that does not contain at least odd harmonics while amplifying both a pulse wave and a continuous wave by using a transmitting driver in common. The goal is to realize a transmitting circuit for an ultrasonic system that can be used.

(Means for Solving the Problems) The present invention, which solves the above problems, has the functions of both an ultrasonic continuous wave Doppler device and an ultrasonic device using ultrasonic pulses, and uses an ultrasonic probe. In a transmission circuit of an ultrasound system that uses a transmission driver for power amplifying a high-frequency signal to be driven for both functions, at least one diode is provided between the output end of the transmission driver and the ultrasound probe. This is characterized by the insertion of a circuit in which a circuit in which a low-pass filter and a low-pass filter are connected in antiparallel.

(Function) Since the antiparallel-connected high-voltage diode and the low-pass filter are connected in parallel, the high-voltage pulse wave is input to the ultrasonic probe and transmitted without loss, and the low-voltage continuous wave is transmitted at the third harmonic. The waves are transmitted in a waveform with the waves and high-order harmonics removed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The figure is a configuration diagram of main parts of an embodiment of the present invention. In the figure, reference numeral 1 denotes a transmission driver that amplifies the power of a transmission high-frequency signal by a switching operation, and transmits a continuous wave (2) and a pulsed wave (2) by switching between them. 2 is a switch circuit constructed by connecting in antiparallel high-voltage operating diodes Ds and D2 connected in series in the same direction and high-voltage operating diodes Di and D4 connected in series in the same direction; 3 is a coil Ls;
This is a low-pass filter in which L2 is connected in series and a capacitor C is inserted between the connection point and the ground.The switch circuit 2 and the low-pass filter 3 are connected in parallel, and one end is connected to the transmitter driver 1. . D5 is the coil L of low-pass filter 2
s, a high-voltage operating diode with its anode connected to the connection point of L2, and its cathode connected to a +5V DC power supply, Da, a 7 node connected to a -5V DC power supply, and the connection point of coils L1 and L2 of low-pass filter 2. It is a high voltage operating diode with its cathode connected to the Reference numeral 4 denotes a transmitting transducer element that converts the output high-frequency signal of the wave transmitting driver 1 into an ultrasonic signal and transmits it into the subject, and a transfer element that receives reflected waves from the subject and converts them into electrical signals. The ultrasonic probe consists of a transducer element, and is connected to the output side connection point of the switch circuit 2 and the low-pass filter 3, and the receiving side is connected to the receiving circuit.

Next, the operation of the apparatus configured as described above will be explained.

During pulse wave transmission, the high frequency pulse signal is amplified by the wave transmitting driver 1 to a high level ranging from 100 volts to ±100 volts and is input to the parallel circuit of the switch circuit 2 and the low-pass filter 3. Constituent diode D1 of switch circuit 2
D4 is conductive because the input signal is at a high level, and diode D
+, 02 is the positive potential of the pulse, diodes D3, D
4 becomes conductive due to the negative potential of the pulse and passes the input signal. Diode D5 is at the positive potential of the pulse, diode D6
conducts due to the negative potential of the pulse, thereby preventing a current with a resonant frequency component from flowing in the capacitor C and the coil L+, and also prevents a part of the high-frequency pulse signal from passing through the low-pass filter 3. The high frequency pulse signal that has passed through the switch circuit 2 is input to the ultrasonic probe 4, where it is converted into an ultrasonic signal and transmitted.

During continuous wave transmission, a high frequency continuous wave is amplified by the wave transmitting driver 1 and output with an amplitude of about volts or less. Since all of the diodes D+-Da operating at a high voltage do not become conductive at a voltage of several volts, the continuous wave signal is blocked by the switch circuit 2 and passes through the low-pass filter 3. If the cutoff frequency of the low-pass filter 3 is appropriately selected, the problematic high-frequency components are removed and a continuous wave in the form of a sine wave is output, which is input to the ultrasound probe 4, converted into an ultrasound signal, and transmitted. Ru.

As explained in detail above, according to the circuit of this embodiment, both operation modes of low level continuous sine wave and high level pulse wave or burst wave are automatically switched and transmitted without switching. It starts to wave.

Note that the present invention is not limited to the above embodiments.

For example, the diode connected to the connection point of the low-pass filter coil can be omitted. Further, although two diodes were used in each switch circuit, the number can be selected appropriately taking into consideration the withstand voltage and operating voltage.

(Effects of the Invention) As described above in detail, according to the present invention, it is possible to automatically optimize and switch between the continuous sine wave and pulse wave operation modes without switching using a switch. The practical effect is great.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a block diagram of main parts of an embodiment of the present invention. 1... Wave transmission driver 2... Switch circuit 3...
・Low pass filter 4...Ultrasonic probe D+-Ds・
··diode

Claims (1)

[Claims] An ultrasound system that has both the functions of an ultrasound continuous wave Doppler device and an ultrasound device that uses ultrasound pulses, and that both functions share a transmission driver that amplifies the power of the high-frequency signal that drives the ultrasound probe. In the transmission circuit, at least one
1. A transmitting circuit for an ultrasonic system, characterized by inserting a circuit in which diodes are connected in antiparallel and a low-pass filter is connected in parallel.