JP2008011925A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic diagnostic apparatus with switching power supply capable of preventing noise to ultrasonic diagnostic images without using a large-scale filter and controlling a power supply voltage to be supplied to an optional voltage value. <P>SOLUTION: The ultrasonic diagnostic apparatus has a continuous wave transmission part for outputting continuous wave (CW) transmission signals to a probe vibrator and the switching power supply for supplying a desired power supply voltage to the continuous wave transmission part in order to determine the voltage of the continuous wave transmission signals. The switching power supply comprises a constant voltage power supply and a step-down chopper type power supply circuit. By turning the frequency of a switching clock for turning a switching element inside the power supply circuit ON/OFF to the frequency higher than the frequency of the continuous wave transmission signals, the noise is prevented from being generated in the ultrasonic diagnostic images. Also, by controlling the duty ratio of the switching clock, the power supply voltage of the optional voltage value is supplied to the continuous wave transmission part. Thus, the power supply voltage to be supplied to the continuous wave transmission part is finely adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a power supply unit of an ultrasonic diagnostic apparatus having a continuous wave transmission unit.

  In the continuous wave (CW) Doppler transmission unit, as shown in FIG. 4, a CW transmission signal is generated by a CW transmission clock generator 12, and the generated CW transmission signal is transmitted as a CW transmission signal. It is transmitted to the ultrasonic probe transducer by the wave circuit 11. The power supply voltage supplied to the CW transmission circuit 11 is generated by the CW voltage circuit 100 by the power output from the constant voltage power supply 13 and applied to + Vcc of the CW transmission circuit 11.

  The transmission voltage of the CW transmission signal is determined by the power supply voltage applied to + Vcc of the CW transmission circuit 11. That is, when it is necessary to increase the transmission voltage, the power supply voltage applied to + Vcc of the CW transmission circuit 11 is increased, and when the transmission voltage may be decreased, the power supply voltage applied to + Vcc of the CW transmission circuit 11 is increased. It was set low.

  When the ultrasonic probe is connected to the ultrasonic diagnostic apparatus, the transmission voltage is set so as not to exceed the ultrasonic transmission power regulation value measured in advance. In general, the ultrasonic wave transmission power differs depending on the type of ultrasonic probe, the transmission frequency, and the number of transmission channels even with the same transmission voltage setting. Therefore, the transmission voltage is set so as not to exceed the ultrasonic transmission power regulation value, and the power supply voltage that becomes the set transmission voltage is generated by the CW voltage circuit 100.

  A conventional example of the CW voltage circuit 100 is shown in FIG. This is a dropper type power supply circuit 101. A constant voltage power supply 13 is used for power input. Then, n types of dropper power supplies 16 for generating n types of power supply voltages are provided, and one of them is selected by the relay 15 according to the type of ultrasonic probe, the transmission frequency, and the number of transmission channels. Selected. For example, in the transmission condition of an ultrasonic probe, the ultrasonic power is exceeded by the m (1 <m <n) -th power supply voltage among n types of power-supply voltages, but it is lower by one step. When the power supply voltage satisfies the ultrasonic power regulation value or less, the m-1st power supply voltage is selected.

  However, since the difference between the ultrasonic power value by the mth power supply voltage and the m-1st power value is not small, the power value when the m-1st voltage is transmitted is the ultrasonic transmission power regulation value. Does not necessarily match. Accordingly, in many cases, a slight power loss occurs compared to the ultrasonic transmission power regulation value, and the maximum sensitivity of CW Doppler cannot be obtained.

  In order to improve it, the type of the power supply voltage 16 is increased, a power supply voltage that interpolates the current power supply voltage value is added, and the transmission voltage value of the CW Doppler closer to the ultrasonic transmission power regulation value is selected. Need to be able to. However, such a configuration generally results in a significant increase in the number of parts of the power supply circuit, which causes an increase in size and cost.

  FIG. 6 shows another conventional example for solving the above problem. This is a switching-type power supply circuit 102, which controls on / off of an input power supply with a predetermined duty ratio using a semiconductor element such as a switching element Ql, and smoothes it to generate a predetermined power supply. In this case, the apparatus can be downsized as compared with the dropper type power supply circuit 101.

  However, when a switching power supply as shown in FIG. 6 is used as a CW Doppler transmission power supply, the crosstalk of the switching clock generated by the oscillation circuit 19 leaks into the power supply line and is displayed on the monitor screen of the ultrasonic diagnostic apparatus. Noise may occur in the ultrasonic diagnostic image. This noise is generated on the monitor screen when the frequency of the switching power supply falls within the CW Doppler band (about 2 to 5 MHz).

In order to cope with this, an ultrasonic observation apparatus (Patent Document 1) in which a switching power supply and a filter are integrally assembled in a case having shielding properties has been proposed.
JP 2001-212141 A

  However, Patent Document 1 has the following drawbacks. In Patent Document 1, a large-scale filter 20 for preventing noise is still necessary, and a case having a shielding property for assembling a switching power supply and a filter is necessary. There was a problem of being a factor.

  The present invention has been made in view of the above circumstances, can prevent noise to an ultrasonic diagnostic image without using a large-scale filter, and can control a power supply voltage to be supplied to an arbitrary voltage value. An object of the present invention is to provide an ultrasonic diagnostic apparatus provided with a switching power supply.

  In order to solve the above problem, the ultrasonic diagnostic apparatus according to claim 1 is for determining a voltage of the continuous wave transmission signal and a continuous wave transmission unit that outputs the continuous wave transmission signal to the probe transducer. In the ultrasonic diagnostic apparatus, the switching power supply generates a switching clock for turning on / off the switching element in the switching power supply. A switching clock control unit is provided, wherein the switching clock control unit generates a switching clock having a frequency outside the frequency band of the continuous wave transmission signal, and controls a duty ratio of the switching clock. According to the above ultrasonic diagnostic apparatus, the switching clock control unit generates a switching clock having a frequency higher than the frequency of the continuous wave transmission signal so that noise is not generated in the ultrasonic diagnostic image, and the duty of the switching clock is increased. By controlling the ratio, a power supply voltage having an arbitrary voltage value is supplied to the continuous wave transmission unit. Thereby, it is possible to prevent noise in the ultrasonic diagnostic image without using a large-scale filter. In addition, the power supply voltage supplied to the continuous wave transmission unit can be controlled.

  The ultrasonic diagnostic apparatus according to claim 2 is the ultrasonic diagnostic apparatus according to claim 1, wherein the switching power supply includes a constant voltage power supply and a step-down chopper type power supply circuit, and the step-down chopper type power supply circuit includes: The switching clock control unit is provided, and the power source voltage input from the constant voltage power source is stepped down and supplied to the continuous wave transmission unit. According to the above ultrasonic diagnostic apparatus, the switching power supply steps down the power supply voltage supplied from the constant voltage power supply by the step-down chopper type power supply circuit and supplies the voltage to the continuous wave transmission unit. Thereby, the power supply voltage supplied to a continuous wave transmission part is controllable.

  According to the present invention, an ultrasonic diagnostic apparatus provided with a switching power supply that can prevent noise in an ultrasonic diagnostic image without using a large-scale filter and can control a supplied power supply voltage to an arbitrary voltage value. Can be provided.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a block diagram of an ultrasonic diagnostic apparatus according to the present invention. The ultrasonic diagnostic apparatus mainly includes an ultrasonic probe transducer 1 composed of a plurality of transducer elements, a changeover switch 2 for switching an ultrasonic transmission method, and a transmitter 8 for supplying a drive signal to the transducer 1. And a receiving unit 9 for processing a received signal output from the vibrator 1.

  The vibrator 1 is mainly composed of a transmitting vibration element T and a receiving vibration element R. An ultrasonic wave is transmitted from the transmitting vibration element T to the subject, and a reflected echo is generated in the process in which the transmitted ultrasonic wave propagates through the subject. The generated reflected echo is received by a receiving vibration element R provided in the vibrator 1 and converted into a received signal.

  The transmission unit 8 mainly includes a B-mode transmission circuit 3 that transmits pulse ultrasonic waves, a CW-mode transmission circuit 4 that transmits continuous waves, and a transmission clock generator that generates a transmission signal. It is composed of five.

  The transmission clock generator 5 includes a clock generator that generates a pulsed ultrasonic wave transmission signal, and a clock generator that generates a continuous wave transmission signal. The transmission signal generated by the clock generator is Output to the B-mode transmission circuit 3 and the CW-mode transmission circuit 4.

  The B-mode transmission circuit 3 transmits the transmission signal of the pulse ultrasonic wave output from the transmission clock generator 5 to the transmission vibration element T provided in the vibrator 1.

  The CW mode transmission circuit 4 transmits the continuous wave transmission signal output from the transmission clock generator 5 to the transmission vibration element T provided in the vibrator 1.

  The changeover switch 2 is provided between the transmission unit 8 and the vibrator 1. By switching the changeover switch 2 between the B-mode transmission circuit 3 and the CW-mode transmission circuit 4, the transmission method of the transmission unit 8 is set to the B-mode method or the CW Doppler method.

  The reception unit 9 includes a preamplifier 6 that amplifies the reception signal and a reception processing circuit 7 that processes the reception signal output from the preamplifier 6. The receiving unit 9 processes the received signal output from the receiving vibration element R provided in the vibrator 1. The reception signal output from the reception vibration element R is amplified by the preamplifier 6, and the amplified reception signal is processed by the reception processing circuit 7 to reconstruct an ultrasonic image (for example, a tomographic image).

  Next, a CW Doppler transmission unit will be described.

  FIG. 2 is a block diagram and a circuit diagram of a CW Doppler transmission unit and a switching power supply for supplying power to the CW Doppler transmission unit of the ultrasonic diagnostic apparatus according to the present invention.

  The CW Doppler transmission unit mainly includes a CW transmission clock generator 12 that generates a CW transmission signal and a CW transmission circuit 11 that outputs the CW transmission signal to an ultrasonic probe transducer. Is done. The switching power supply mainly includes a constant voltage power supply 13 and a switching power supply circuit 103 that converts a power supply voltage supplied from the constant voltage power supply 13 and supplies a predetermined power supply voltage to the CW transmission circuit 11. The

  The CW transmission clock generator 12 generates a rectangular wave continuous signal that is a CW transmission signal, and outputs the generated CW transmission signal to the CW transmission circuit 11.

  The CW transmission circuit 11 is turned ON / OFF by the CW transmission signal input from the CW transmission clock generator 12, and transmits the CW transmission signal at a voltage of 0 to + Vcc. The transmission voltage of the CW transmission signal is determined by the voltage applied to + Vcc of the CW transmission circuit 11. Normally, in the CW Doppler system, a signal of about 5 Vpp and about 2 to 5 MHz is output from the CW transmission circuit 11 as a continuous wave. That is, the voltage applied to + Vcc of the CW transmission circuit 11 is about 5V.

  The switching power supply circuit 103 is a chopper type step-down circuit, and is mainly a switching clock control that generates a switching clock for turning on / off the switching element Q1, the diode D1, the choke coil L1, the capacitor C1, and the switching element Q1. The circuit 18 is configured. The switching power supply circuit 103 steps down the power supply voltage supplied from the constant voltage power supply 13 to a predetermined voltage and applies it to + Vcc of the CW transmission circuit 11.

  The switching clock control circuit 18 outputs a switching clock for turning on / off the switching element Q1. The switching element Q1 is turned ON / OFF by the switching clock. When the switching element Q1 is ON, a current flows from the constant voltage power supply 13 to the choke coil L1 via the switching element Q1, and when it is OFF, a current flows from the diode D1 to the choke coil L1. Smoothed by the capacitor C1. The smoothed DC voltage is supplied from the switching power supply circuit 103 to the CW transmission circuit 11. The switching clock frequency and duty ratio are controlled by the switching clock control circuit 18.

  Next, a method for controlling the voltage applied to + Vcc of the CW transmission circuit 11 to an arbitrary voltage value by the switching power supply circuit 103 will be described.

  FIG. 3 shows a clock chart of this switching clock. When the input voltage of the switching power supply circuit 103 when the ON time is Ton with respect to the repetition period T is Vin, the output voltage Vout of the switching power supply circuit 103 is expressed by the following equation.

Vout = Vin × (Ton / T)
For example, if the power supply generated by the constant voltage power supply 13 is 15 V, T = 150 ns, and Ton = 50 ns, the output voltage Vout is
Vout = 15V × (50ns / 150ns) = 5V
It becomes.

  As described above, by controlling the duty ratio of the switching clock, the voltage value supplied from the switching power supply circuit 103 to the CW transmission circuit 11 can be stepped down to a predetermined voltage.

  Next, a method for preventing noise in the ultrasonic diagnostic image by the switching power supply circuit 103 will be described.

The clock frequency fc output from the switching clock control circuit 18 is
fc = 1 / T
Can be expressed as If the repetition period T is set so that the clock frequency fc is outside the CW Doppler frequency band, the influence of noise due to the crosstalk of the switching clock can be prevented. The transmission frequency of the CW Doppler is about 2 to 5 MHz. For example, when the transmission frequency is 2 MHz, the clock frequency is outside the band other than the transmission frequency ± 100 kHz which is the band of the transmission frequency, that is, 2.1 MHz or higher and 1. What is necessary is just to make it 9 MHz or less. In the case of a clock frequency of 1.9 MHz or less, the frequency is set such that the harmonic does not fall within the band.

  As described above, by setting the clock frequency of the switching clock to be out of the CW Doppler frequency band, even when no filter is inserted between the switching power supply circuit 103 and the CW transmission circuit 11, the ultrasonic wave It is possible to prevent noise from being generated in the ultrasonic diagnostic image displayed on the monitor screen of the diagnostic apparatus. As a result, a large-scale filter is not required, and the power supply circuit can be downsized or reduced in price.

  Although the case of the CW Doppler method has been described in this embodiment, the present invention is used by setting the clock frequency of the switching clock outside the transmission frequency band even in cases other than the CW Doppler method. be able to.

  In this embodiment, the step-down chopper type switching power supply circuit is used. However, the present invention is not limited to the step-down chopper type, and other known switching power supply circuits such as a step-up chopper type can be used.

1 is a block diagram of an ultrasonic diagnostic apparatus to which the present invention is applied. It is a block diagram and a circuit diagram of a power supply for a CW Doppler wave transmission unit and a CW Doppler wave transmission unit in the ultrasonic diagnostic apparatus. It is a control signal of the switching clock control circuit which controls the switching power supply which is a power supply for CW Doppler transmission parts in the ultrasonic diagnostic apparatus. It is a block diagram of a power supply for a CW Doppler transmission unit and a CW Doppler transmission unit in a conventional ultrasonic diagnostic apparatus. It is a circuit diagram of the power supply for CW Doppler transmission parts in the conventional ultrasonic diagnostic apparatus. It is a circuit diagram of the power supply for CW Doppler transmission parts in the conventional ultrasonic diagnostic apparatus.

Explanation of symbols

1: ultrasonic probe transducer, 2: changeover switch, 3: B mode transmission circuit, 4: CW mode transmission circuit, 5: transmission clock generator, 6: preamplifier, 7: reception processing circuit , 8: transmitting unit, 9: receiving unit, 11: CW transmitting circuit, 12: CW transmitting clock generator, 13: constant voltage power supply, 18: switching clock control circuit, 100: CW voltage circuit, 101: Dropper power supply circuit, 102: switching power supply circuit, 103: switching power supply circuit

Claims (2)

An ultrasonic diagnosis comprising: a continuous wave transmission unit that outputs a continuous wave transmission signal to a vibrator; and a switching power supply that supplies a desired power supply voltage to the continuous wave transmission unit in order to determine a voltage of the continuous wave transmission signal In the device
The switching power supply includes a switching clock control unit that generates a switching clock for turning ON / OFF a switching element in the switching power supply,
The ultrasonic diagnostic apparatus, wherein the switching clock control unit generates a switching clock having a frequency outside a frequency band of the continuous wave transmission signal and controls a duty ratio of the switching clock. The switching power supply includes a constant voltage power supply and a step-down chopper type power supply circuit,
The step-down chopper type power supply circuit includes the switching clock control unit, and steps down a power supply voltage input from the constant voltage power supply and supplies the stepped-down chopper type power supply circuit to the continuous wave transmission unit. Ultrasound diagnostic equipment.

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