WO2013137061A1 - Ultrasonic diagnostic device and noise reduction method - Google Patents

Ultrasonic diagnostic device and noise reduction method Download PDF

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Publication number
WO2013137061A1
WO2013137061A1 PCT/JP2013/055982 JP2013055982W WO2013137061A1 WO 2013137061 A1 WO2013137061 A1 WO 2013137061A1 JP 2013055982 W JP2013055982 W JP 2013055982W WO 2013137061 A1 WO2013137061 A1 WO 2013137061A1
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WIPO (PCT)
Prior art keywords
frequency
switching
signal
fsw
unit
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PCT/JP2013/055982
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French (fr)
Japanese (ja)
Inventor
玉野　聡
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日立アロカメディカル株式会社
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Priority to JP2014504807A priority Critical patent/JP6166255B2/en
Publication of WO2013137061A1 publication Critical patent/WO2013137061A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
    • G01S7/52077—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging with means for elimination of unwanted signals, e.g. noise or interference
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/5215—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
    • G01S15/8979—Combined Doppler and pulse-echo imaging systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
    • G01S7/52096—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging related to power management, e.g. saving power or prolonging life of electronic components
    • G—PHYSICS
    • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
    • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
    • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
    • G16H50/20—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for computer-aided diagnosis, e.g. based on medical expert systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/56—Details of data transmission or power supply

Definitions

  • the present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that reduces noise.
  • miniaturization of the ultrasonic diagnostic equipment is progressing along with the improvement of the performance of arithmetic devices such as CPU, GPU and FPGA.
  • arithmetic devices such as CPU, GPU and FPGA.
  • Patent Document 1 a technique for changing the switching frequency of the power supply circuit in accordance with the pulse repetition frequency of the ultrasonic diagnostic apparatus has been proposed (for example, Patent Document 1).
  • the present invention provides an ultrasonic diagnostic apparatus that reduces noise caused by a power supply circuit and does not superimpose power supply noise on the result of Doppler frequency analysis by pulse Doppler (PWD) or continuous wave Doppler (CWD). For the purpose.
  • PWD pulse Doppler
  • CWD continuous wave Doppler
  • the ultrasonic diagnostic apparatus detects a received ultrasonic signal using a reference wave frequency and a power supply unit that adjusts the voltage by turning on and off the switching power supply unit using the switching frequency.
  • a detection unit an analog signal of the reception signal using a sampling frequency, an A / D conversion unit that converts the reception signal from the analog signal to a digital signal, the reference wave frequency, the switching frequency, and
  • a control unit that performs control satisfying the following formula by controlling at least one of the sampling frequencies.
  • Fref n * Fsw (n-1) * Fsw ⁇ Fref- (1/2) Fadc Fref + (1/2) Fadc ⁇ (n + 1) * Fsw N: Positive integer
  • Fref Reference wave frequency
  • Fsw Switching frequency
  • Fadc Sampling frequency
  • the ultrasonic diagnostic apparatus of the present invention uses a switching frequency to turn on / off the switching power supply unit, and adjusts the voltage, and uses the sampling frequency to sample an analog signal of the ultrasonic reception signal.
  • An A / D converter that converts the received signal from the analog signal to a digital signal, and a controller that performs control that satisfies the following formula by controlling at least one of the switching frequency and the sampling frequency: Is provided.
  • the ultrasonic diagnostic apparatus detects a received ultrasonic signal using a reference wave frequency and a power supply unit that adjusts the voltage by turning on and off the switching power supply unit using the switching frequency.
  • a detection unit an analog signal of the reception signal using a sampling frequency, an A / D conversion unit that converts the reception signal from the analog signal to a digital signal, the reference wave frequency, the switching frequency, and
  • a control unit that performs control satisfying the following formula by controlling at least one of the sampling frequencies.
  • the ultrasonic diagnostic apparatus uses a switching frequency to turn on / off the switching power supply unit, adjusts the voltage, and uses the analysis frequency to frequency-analyze the ultrasonic reception signal.
  • the ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency.
  • noise can be removed together with the removal component, and other harmonic components can also be removed.
  • the filter unit is common to a filter unit that removes clutter components of the received signal.
  • the common filter unit can remove noise together with the removal component. Also, an ultrasonic diagnostic apparatus that achieves space saving and cost reduction can be realized by a common filter unit.
  • the ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency, and the filter unit is provided in front of the A / D conversion unit.
  • This configuration can support analog CWD processing or analog PWD processing.
  • the ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency, and the filter unit is provided at a subsequent stage of the A / D conversion unit and has a frequency equal to or greater than 1 ⁇ 2 of the analysis frequency. Remove frequency components.
  • This configuration is compatible with HPRF (High Pulse Repetition Frequency) mode.
  • the received signal is a Doppler signal in which an ultrasonic pulse transmitted repeatedly is reflected by an object.
  • the noise reduction method of the present invention adjusts the voltage by turning on / off the FET of the switching power supply unit using the switching frequency, performs detection of the ultrasonic reception signal using the reference wave frequency, and performs sampling. Sampling an analog signal of the received signal using a frequency, converting the received signal from the analog signal to a digital signal, and controlling at least one of the reference wave frequency, the switching frequency, and the sampling frequency; Thus, control satisfying the following mathematical formula is performed.
  • Fref n * Fsw (n-1) * Fsw ⁇ Fref- (1/2) Fadc Fref + (1/2) Fadc ⁇ (n + 1) * Fsw N: Positive integer
  • Fref Reference wave frequency
  • Fsw Switching frequency
  • Fadc Sampling frequency
  • the present invention can provide an ultrasonic diagnostic apparatus that reduces noise caused by a power supply circuit and has an effect that power supply noise is not superimposed on the result of Doppler frequency analysis.
  • FIG. 1 is a block diagram showing an example of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.
  • Diagram showing an example of a switching power supply circuit Block diagram showing an example of a circuit that performs analog CWD processing or analog PWD processing
  • (a) Diagram showing frequency component of received signal (b) Diagram showing harmonic component distribution when switching frequency Fsw is 100 KHz, (c) Harmonic component distribution when switching frequency Fsw is 150 KHz
  • Diagram showing the passband of the filter section and the frequency analysis range of the frequency analysis section The figure which showed the harmonic component distribution after the harmonic component of switching frequency Fsw and the low frequency component which accompanies it were removed
  • (a) Diagram showing that harmonic components of switching frequency Fsw do not exist within the range of the signal processing region (b) Shows that harmonic components of switching frequency Fsw and the accompanying low frequency components are removed.
  • FIG. 1 Figure Block diagram of a circuit that performs analog CWD processing or analog PWD processing in HPRF mode
  • FIG. 1 is a block diagram showing an example of an ultrasonic diagnostic apparatus according to the present embodiment.
  • the ultrasonic diagnostic apparatus 1 transmits and receives ultrasonic waves into the subject 2 via the ultrasonic probe 3, and uses the echo signal obtained by reception to diagnose the subject 2.
  • a two-dimensional ultrasonic image of the part, a three-dimensional ultrasonic image, various Doppler images, and the like are formed, and these images are displayed on the display unit 6.
  • the ultrasonic diagnostic apparatus 1 includes an ultrasonic probe 3, an ultrasonic transmission / reception unit 4, an ultrasonic image forming unit 5, a display unit 6, a control unit 7, a control panel 8, a power supply unit 9, And a clock circuit unit 10.
  • the ultrasonic probe 3 transmits ultrasonic waves to the subject 2 and receives echoes reflected by the target object.
  • the ultrasonic probe 3 includes an ultrasonic vibration section in which a plurality of transducer elements are arrayed and arranged in 1 to m channels in the longitudinal direction of the ultrasonic probe 3, and the ultrasonic probe 3 Ultrasonic waves are applied to the subject 2 from the ultrasonic vibration unit.
  • the ultrasonic probe 3 may be a linear array probe having a strip type transducer or a two-dimensional array probe.
  • the ultrasonic transmission circuit 4a generates an ultrasonic transmission signal according to the control of the control unit 7.
  • the ultrasonic reception circuit 4b receives a reception signal from the ultrasonic vibration unit of the ultrasonic probe 3 (for example, a Doppler signal in which an ultrasonic pulse transmitted repeatedly is reflected by an object), and the control unit 7
  • the phasing process of the received signal is performed by the phasing delay control.
  • the ultrasonic image forming unit 5 forms a two-dimensional ultrasonic image, a three-dimensional ultrasonic image, and various Doppler images from the received signal.
  • the display unit 6 displays the ultrasonic image formed by the ultrasonic image forming unit 5.
  • the control unit 7 controls each element of the ultrasonic diagnostic apparatus 1.
  • the control panel 8 gives an instruction to the control unit 7 by the operation of the operator.
  • the clock circuit unit 10 includes a clock frequency dividing circuit 10a.
  • the clock frequency dividing circuit 10a generates a sample clock of the A / D conversion circuit (A / D conversion unit) 4c and a switching signal of the switching power supply circuit (switching power supply unit) 9a according to the control of the control unit 7.
  • the power supply unit 9 supplies power for operation to the ultrasound diagnostic apparatus 1.
  • the power supply unit 9 includes a switching power supply circuit (switching power supply unit) 9a that efficiently raises and lowers the voltage from an intermediate potential to a potential voltage suitable for the device. That is, the power supply unit 9 adjusts the voltage by turning on / off the FET of the switching power supply circuit 9a using the switching frequency.
  • FIG. 2 is a block diagram showing a step-down switching power supply circuit as an example of the switching power supply circuit 9a.
  • the switching power supply circuit 9a uses the switching power supply controller 2-1 to turn on / off the FET1 (high side FET) and FET2 (low side FET), thereby changing the voltage from the intermediate potential to the potential voltage suitable for the device. Reduce pressure efficiently.
  • the ultrasonic transmission / reception unit 4 includes an ultrasonic transmission circuit 4a, an ultrasonic reception circuit 4b, an A / D conversion circuit 4c, and a phasing circuit 4d.
  • the ultrasonic transmission circuit 4a generates a pulsed electric signal and generates an ultrasonic signal to be transmitted to the subject 2.
  • the ultrasonic receiving circuit 4b receives the echo signal received by the ultrasonic probe 3.
  • the A / D conversion circuit 4c converts the reception signal received by the ultrasonic reception circuit 4b into a digital signal.
  • the A / D conversion circuit 4c samples the analog signal of the ultrasonic reception signal using the sampling frequency Fadc, and converts the reception signal from an analog signal to a digital signal.
  • the phasing circuit 4d performs phasing processing on the received signal.
  • the ultrasonic transmission / reception unit 4 includes a complex signal conversion unit (not shown) that performs orthogonal detection on the echo signal received by the ultrasonic reception circuit 4b and converts it into a complex signal.
  • the ultrasonic image forming unit 5 forms an ultrasonic tomographic image using the complex signal converted by the complex signal converting unit of the ultrasonic transmitting / receiving unit 4.
  • the ultrasonic image forming unit 5 includes an ultrasonic image information generation unit 5a, a digital scan converter unit (DSC unit) 5b, a graphic data generation unit 5c, a synthesis storage unit 5d, and an interface 5e.
  • the ultrasonic image information generation unit 5a generates ultrasonic image information of an inspection target (including an object) using a complex signal.
  • the DSC unit 5b scan-converts the generated ultrasonic image information into a television display image pattern, and generates ultrasonic image data.
  • the DSC unit 5b causes the display unit 6 to display an ultrasonic image using the phasing processing signal of the ultrasonic receiving circuit 4b.
  • the DSC unit 5b configures a B-mode image, an M-mode image, a Doppler image, a blood flow image, and the like, which are ultrasonic images, and displays them on the display unit 6.
  • the graphic data generation unit 5c generates graphic data such as a scale, a mark, and a character attached to the ultrasonic image based on the ultrasonic image data obtained by the scan conversion by the DSC unit 5b.
  • the synthesis storage unit 5d synthesizes and stores the ultrasonic image data generated by the DSC unit 5b and the graphic data generated by the graphic data generation unit 5c.
  • the composite storage unit 5d includes a hard disk, a temporary storage memory RAM, and the like.
  • the interface 5e displays initial values and control parameters required for various processes of the ultrasonic image information generation unit 5a, the DSC unit 5b, the graphic data generation unit 5c, and the synthesis storage unit 5d. It is read out and set in the ultrasonic image information generation unit 5a, the DSC unit 5b, the graphic data generation unit 5c, and the synthesis storage unit 5d.
  • the display unit 6 displays the image formed by the ultrasonic image forming unit 5 as an ultrasonic image.
  • the display unit 6 includes, for example, a CRT monitor or a liquid crystal monitor.
  • the control unit 7 includes a control computer system that controls the operation of each component of the ultrasonic diagnostic apparatus 1 according to an instruction from the control panel 8 and has an interface with a user interface circuit (not shown).
  • the control unit 7 controls the user interface circuit, and controls the ultrasonic transmission / reception unit 4, the ultrasonic image forming unit 5, and the like based on information from the user interface circuit. Further, the control unit 7 performs control for transmitting information imaged by the ultrasonic image forming unit 5 to a display control unit (not shown) of the display unit 6.
  • the ultrasonic diagnostic apparatus 1 reduces EMI noise generated by the power supply unit 9 and ultrasonic image noise generated by the switching power supply circuit 9a.
  • the performance of digital devices such as CPU, GPU, FPGA, and ASIC has been improved.
  • the IC process has been miniaturized.
  • the operating speed in the IC has increased, the IC power supply voltage has decreased, and the instantaneous current of the device supply power has increased.
  • the power supply unit 9 is provided in the vicinity of the device, and efficiently raises and lowers the voltage from the intermediate potential to the potential voltage suitable for the device.
  • the PointofLoad (POL) power supply method using sapphire has come to be used.
  • the ultrasonic diagnostic apparatus 1 is a power supply circuit system suitable for the ultrasonic diagnostic apparatus 1 by reducing these noises.
  • FIG. 3 is a block diagram of a circuit that performs analog CWD processing or analog PWD processing.
  • the reception signal amplification circuit 4-1 of the ultrasonic reception unit 4 amplifies the reception signal 100.
  • a mixing circuit (detection unit) 4-2 receives a reference wave signal (reference wave frequency Fref) for quadrature detection from the demodulated signal generator 4-8 in order to extract a Doppler modulation signal, according to the transmission frequency. Using the reference wave signal, the received signal 101 is quadrature-detected with a phase corresponding to the Doppler data sample position.
  • reference wave signal reference wave frequency Fref
  • the mixing circuit (detection unit) 4-2 detects the ultrasonic reception signal using the reference wave frequency Fref.
  • the channel addition circuit 4-3 performs addition processing on the reception signal 102 subjected to quadrature detection.
  • the wall filter (filter unit) 4-4 is an analog high-pass filter (AHPF), and is added to receive low-frequency components caused by body movement and extract blood flow component signals. A filtering process is performed on the signal 103.
  • the analog anti-aliasing filter (filter unit) 4-5 receives signals below the Nyquist frequency of the received signal 104 so that aliasing does not occur in the subsequent CW / PW-ADC (A / D converter) 4-6. Let it pass.
  • the CW / PW-ADC (A / D converter) 4-6 samples the Doppler signal (received signal 105) that has undergone analog signal band processing at the sampling frequency Fadc based on the CW / PW-ADC converted signal (AD conversion clock). Process and convert to digital signal at hold time.
  • the filtered analog Doppler signal is required to be accurately converted to a digital signal, and an ADC of about 16 bits or more is required.
  • a method of converting to a digital signal at about 100 KHz to about 1 MHz is used in an ultrasonic diagnostic apparatus.
  • the Doppler signal converted into a digital signal is transmitted to the ultrasonic image information generation unit 5a.
  • the Doppler frequency analysis circuit (frequency analysis unit) 4-7 of the ultrasonic image information generation unit 5a performs frequency analysis by a frequency analysis method such as FFT.
  • the Doppler signal subjected to frequency analysis is displayed on the display unit 6 via the DSC unit 5b.
  • FIG. 4 is a diagram illustrating a result of frequency analysis of a Doppler signal in a continuous wave Doppler method (CWD) mode or a pulse Doppler method (PWD) mode.
  • the vertical axis represents signal intensity
  • the horizontal axis represents frequency related to Doppler signal processing.
  • the sampling frequency Fadc of the CW / PW-ADC 4-6 is set to 300 KHz continuously in the CWD mode, and 300 KHz in synchronization with repeated ultrasonic transmission in the PWD mode.
  • Fig. 4 (a) shows the frequency components of the received signal.
  • a Clutter component and a Doppler component are Doppler signal processing regions centered on a transmission / reception signal center frequency (reference wave frequency Fref).
  • a “Fref ⁇ (1/2) Fadc ⁇ A ⁇ Fref + (1/2) Fadc” appears.
  • the clutter component is a biological tissue motion component caused by organ movement during breathing, etc., and is removed by the wall filter (filter unit) 4-4 to prevent detection of a blood flow Doppler signal with a relatively weak signal strength. .
  • FIG. 4 (b) is a diagram showing the harmonic component distribution when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz.
  • FIG. 4 (c) is a diagram showing a harmonic component distribution when the switching frequency Fsw of the switching power supply circuit 9a is 150 KHz.
  • the switching noise is a positive integer multiple of the switching frequency Fsw (100 KHz) (100 KHz, 200 KHz, 300 KHz ... ) Appears as harmonic noise.
  • the switching noise is a positive integer multiple of the switching frequency Fsw (150 kHz) (150 kHz, 300 kHz, 450 kHz ... ⁇ ⁇ ) Appears as harmonic noise. Further, the spectrum spreads in the vicinity of a positive integer multiple of the switching frequency Fsw. This is because the power supply load state of the ultrasound diagnostic apparatus 1 changes from moment to moment according to the ultrasound transmission position, the contents of the computation process, the computation process state, the display state, and the apparatus operation state. This is because the On / Off duty ratio of FET1 and FET2 changes from moment to moment, and the effect appears as a low frequency component in the frequency domain.
  • FIG. 5 (a) is a diagram showing that Doppler components after quadrature detection and switching noise are superimposed when the switching frequency Fsw of the switching power supply circuit 9a is 100 kHz.
  • FIG. 5 (b) is a diagram showing that Doppler components after quadrature detection and switching noise do not overlap when the switching frequency Fsw of the switching power supply circuit 9a is 150 kHz.
  • the clutter component and the Doppler component blood flow Doppler component
  • FIG. 6 (a) shows the passband of the wall filter 4-4 (analog high-pass filter AHPF).
  • FIG. 6 (b) is a diagram showing the passband of the analog anti-aliasing filter (AAF) 4-5.
  • FIG. 6 (c) is a diagram showing a frequency analysis range according to the sampling frequency Fadc of the CW / PW-ADC 4-6.
  • the wall filter 4-4 is an analog high-pass filter (AHPF) and removes clutter components. Since the sampling frequency Fadc of CW / PW-ADC4-6 is 300 KHz, the harmonic component (300 KHz) of the switching frequency Fsw at a positive integer multiple of the sampling frequency Fadc (300 KHz) is obtained by the filtering process of the wall filter 4-4. , 600KHz, 900KHz ...) and the accompanying low frequency components are removed. On the other hand, the harmonic component of the switching frequency Fsw and the low frequency component associated therewith other than a positive integer multiple of the sampling frequency Fadc (300 KHz) are not removed.
  • AHPF analog high-pass filter
  • FIG. 7 (a) shows the harmonics of the switching frequency Fsw by the filtering process of the wall filter (filter unit) 4-4 and the AAF (filter unit) 4-5 when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz. It is the figure which showed the harmonic component distribution after the wave component and the low frequency component accompanying it were removed. As shown in Fig. 7 (a), harmonic components ( ⁇ 100KHz) of the switching frequency Fsw are removed within the range of ⁇ 1/2 ( ⁇ 150KHz) of the sampling frequency (300KHz) of CW / PW-ADC4-6. Instead, Doppler components and switching noise are superimposed. When the Doppler component and the switching noise are superimposed and imaged by the ultrasonic image forming unit 5, the noise due to the harmonic component of the switching frequency Fsw and the accompanying low frequency component is displayed on the display unit 6.
  • FIG. 7 (b) shows that when the switching frequency of the switching power supply circuit 9a is 150 KHz, the harmonic component of the switching frequency Fsw and the accompanying low frequency component are obtained by the filtering process of the wall filter 4-4 and AAF4-5. It is the figure which showed the harmonic component distribution after removing.
  • the harmonic component of the switching frequency Fsw does not exist within the range of ⁇ 1/2 ( ⁇ 150 KHz) of the sampling frequency Fadc (300 KHz) of the CW / PW-ADC4-6. Doppler component and switching noise do not overlap. As a result, the noise caused by the harmonic component of the switching frequency Fsw and the accompanying low frequency component is reduced.
  • control unit 7 matches the first harmonic component of the switching frequency Fsw to the reference wave frequency Fref, and is different from the first harmonic component of the switching frequency Fsw in the range of the signal processing region A of the Doppler signal.
  • the reference wave frequency Fref is the switching frequency.
  • the control unit 7 controls at least one of the reference wave frequency Fref and the switching frequency Fsw so as to be a positive integer multiple (n times) of Fsw.
  • the harmonic component of the switching frequency Fsw does not exist within the range of ⁇ 1/2 of the sampling frequency Fadc of the CW / PW-ADC4-6. Therefore, as shown in FIG. 4 (c), the frequency “(n ⁇ 1) * of the harmonic component F2 (second harmonic component) existing on the lower frequency side than the first harmonic component F1.
  • the controller 7 controls the control unit 7 so that at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that “Fsw” is equal to or lower than the Doppler signal processing area A “Fref ⁇ (1/2) Fadc” on the low frequency side. Control one.
  • the harmonic component of the switching frequency Fsw does not exist within the range of ⁇ 1/2 of the sampling frequency Fadc of the CW / PW-ADC4-6. Therefore, as shown in FIG. 4 (c), the frequency “(n + 1) * Fsw” of the harmonic component F3 (third harmonic component) existing on the higher frequency side than the first harmonic component F1 is Then, the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that the Doppler signal processing area A on the high frequency side becomes “Fref + (1/2) Fadc” or more.
  • These controls are expressed in mathematical formulas as follows.
  • Fref n * Fsw (1) (n-1) * Fsw ⁇ Fref- (1/2) Fadc (2) Fref + (1/2) Fadc ⁇ (n + 1) * Fsw (3) N: Positive integer Fref: Reference wave frequency
  • Fsw Switching frequency of switching power supply circuit 9a
  • Fadc Sampling frequency of CW / PW-ADC4-6
  • the control unit 7 controls the reference wave frequency Fref, switching frequency Fsw, By controlling at least one of the sampling frequency Fadc, the first harmonic component and the reference wave frequency Fref are matched, and the second and third harmonic components are within the range of the Doppler signal processing region A. It can be made non-existent.
  • the first harmonic component is allowed to exist within the Doppler signal processing region A (center of the Doppler signal processing region A).
  • the first harmonic component is removed by the wall filter (filter unit) 4-4 together with the clutter component. That is, the filter unit that removes the low-frequency component caused by the FET duty ratio change of the switching power supply circuit 9a is common to the filter unit (wall filter 4-4) that removes the clutter component of the ultrasonic reception signal.
  • Other harmonic components are also removed by the AAF (filter unit) 4-5.
  • this embodiment is advantageous in that the switching power supply circuit 9a and the CW / PW-ADC 4-6 with low power consumption and low cost can be used.
  • the clock dividing circuit 10a generates the sample clock of the CW / PW-ADC 4-6 and the switching signal of the switching power supply circuit 9a in synchronization with the ultrasonic transmission timing.
  • control unit 7 changes the switching frequency so as to satisfy the following equation instead of the above equation: At least one of Fsw and sampling frequency Fadc may be controlled.
  • Fsw n * (1/2) Fadc (4) N: positive integer
  • Fsw switching frequency of switching power supply circuit 9a
  • Fadc sampling frequency of CW / PW-ADC4-6
  • sampling frequency Fadc of CW / PW-ADC4-6 is 300KHz
  • switching frequency Fsw is 150KHz
  • the control unit 7 controls at least one of the sampling frequency Fadc and the switching frequency Fsw so as to be a positive integer multiple (n times).
  • the harmonic component switching noise
  • the filter unit that removes the harmonic component of the switching frequency is common to the filter unit (wall filter 4-4) that removes the clutter component of the ultrasonic reception signal.
  • Other harmonic components are also removed by the AAF (filter unit) 4-5.
  • control unit 7 controls at least one of the switching frequency Fsw and the sampling frequency Fadc, thereby matching the first harmonic component and the reference wave frequency Fref, and the range of the Doppler signal processing region A.
  • the second and third harmonic components can be absent.
  • control unit 7 replaces the above equation with the reference wave so as to satisfy the following equation: At least one of the frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc may be controlled.
  • FIG. 6 is a diagram showing that the data does not exist within the range of A. As shown in FIG. 8 (a), the frequency “n * Fsw” of the harmonic component F4 (fourth harmonic component) existing on the lower frequency side than the transmission / reception signal center frequency (reference wave frequency) Fref is low.
  • the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that the frequency side Doppler signal processing area A becomes “Fref ⁇ (1/2) Fadc” or less. Further, the frequency “(n + 1) * Fsw” of the harmonic component F5 (fifth harmonic component) existing on the high frequency side from the transmission / reception signal center frequency (reference wave frequency) Fref is the high frequency side Doppler signal processing area A.
  • the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so as to be equal to or higher than “Fref + (1/2) Fadc”.
  • the sampling frequency Fadc of the CW / PW-ADC4-6 is 300 KHz and the reference wave frequency Fref is 3 MHz (3000 KHz)
  • the switching frequency Fsw is 400 KHz
  • the harmonic component of the switching frequency Fsw and the accompanying low-frequency component are removed by the filtering process of the wall filter 4-4 and the AAF 4-5.
  • the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc, so that the harmonic component of the switching frequency Fsw is within the range of the Doppler signal processing region A. Can be absent.
  • the harmonic component of the switching frequency Fsw is within the range of the Doppler signal processing region A.
  • the present invention can also be applied to the HPRF (High Pulse Repetition Frequency) mode of the ultrasonic diagnostic apparatus 1.
  • HPRF High Pulse Repetition Frequency
  • the PRF Pulse Repetition Frequency
  • FIG. 9 is a block diagram of a circuit that performs digital CWD processing or digital PWD processing in the HPRF mode.
  • the amplified analog signal (received signal 101) is converted into a digital signal for each channel by ADC (A / D converter) 4-16 (received signal 1002), and as a digital signal, A quadrature detection is performed by the digital mixing circuit 4-12 (received signal 1102), and a phasing addition is performed by the channel adder 4-13.
  • ADC A / D converter
  • ADC 4-16 samples the analog signal of the ultrasonic reception signal using the sampling frequency Fadc, and converts the reception signal from an analog signal to a digital signal.
  • the ADC 4-16 digitally converts the received signal 101 using a sampling rate that is at least twice the center frequency of the received signal (for example, a sampling frequency Fadc of about 2 MHz or higher).
  • the channel adder 4-13 digitally multiplies the reference wave signal for quadrature detection (reference wave frequency Fref) and the reception signal subjected to phasing addition to extract a Doppler demodulated signal (reception signal 1103).
  • the channel adder 4-13 digitally multiplies the received signal 1002 converted digitally by a reference wave signal for each channel, and removes unnecessary high frequency components.
  • phasing addition may be performed.
  • the digitally demodulated Doppler demodulated signal is input to the digital filter 4-14 and subjected to signal processing in order to extract a necessary Doppler signal after channel addition processing.
  • an appropriate filter such as FIR, IIR or IFFT may be used.
  • the digital filter 4-14 removes a low frequency component (clutter component) caused by low-speed biological motion such as heart wall motion. Further, the digital filter 4-14 removes frequency components that are 1/2 or more of the analysis frequency (Fanalyze) for the Doppler frequency analysis circuit 4-7 (frequency analysis unit) to analyze the frequency of the Doppler signal.
  • the analysis frequency Fanalyze may be different from the PRF of the ultrasonic diagnostic apparatus 1. In particular, in the HPRF mode, the analysis frequency Fanalyze may be different from the PRF of the ultrasonic diagnostic apparatus 1.
  • the Doppler frequency analysis circuit 4-7 performs frequency analysis of the Doppler signal based on the analysis frequency Fanalyze by a frequency analysis method such as FFT.
  • the Doppler signal subjected to frequency analysis is displayed on the display unit 6 via the DSC unit 5b.
  • FIG. 10 (a) is a diagram showing frequency components of the received signal, as in FIG. 4 (a).
  • a clutter component and a Doppler component for example, a blood flow Doppler component
  • the transmission / reception signal center frequency reference wave frequency Fref
  • FIG. 10 (b) is a diagram showing the result of re-sampling by the ADC 4-16 for each analysis frequency Fanalyze.
  • the Doppler frequency analysis circuit 4-7 operates at each analysis frequency Fanalyze (1 * Fanalyze, 2 * Fanalyze, 3 * Fanalyze, 4 * Fanalyze, 5 * Fanalyze ).
  • FIG. 11 (a) is a diagram showing that switching noise is superimposed on the resampling result.
  • FIG. 11 (b) shows that switching noise is not superimposed on the resampling result.
  • the switching frequency Fsw is a positive integer multiple (n times) 1/2 of the analysis frequency Fanalyze of the Doppler frequency analysis circuit 4-7.
  • switching noise is superimposed on the clutter component. Since the switching noise superimposed on the clutter component is removed together with the clutter component by the digital filter 4-14, the switching noise is not superimposed on the resampling result of the Doppler frequency analysis circuit 4-7.
  • control unit 7 may control at least one of the switching frequency Fsw and the analysis frequency Fanalyze so as to satisfy the following formula. That is, the control unit 7 controls one of the switching frequency Fsw and the analysis frequency Fanalyze so that switching noise is not superimposed on the resampling result of the Doppler frequency analysis circuit (frequency analysis unit) 4-7.
  • Fsw n * (1/2) Fanalyze (7) N: positive integer
  • Fsw switching frequency of switching power supply circuit 9a
  • Fanalyze analysis frequency of Doppler frequency analysis circuit 4-7
  • the control unit 7 controls at least one of the switching frequency Fsw and the analysis frequency Fanalyze.
  • the harmonic component (switching noise) is removed together with the clutter component by the digital filter (filter unit) 4-14. That is, the filter unit that removes the harmonic component of the switching frequency is the same as the filter unit (digital filter 4-14) that removes the clutter component of the ultrasonic reception signal.
  • the common filter unit can remove switching noise together with a removal component (for example, a clutter component). Also, an ultrasonic diagnostic apparatus that achieves space saving and cost reduction can be realized by a common filter unit.
  • the switching noise mixed in the Doppler signal can be reduced.
  • the switching noise of the switching power supply circuit 9a is removed by the filtering process.
  • the switching power supply circuit 9a is controlled so as not to generate switching noise in the Doppler signal processing area A.
  • switching noise since switching noise is not superimposed on the Doppler signal, switching noise can be removed from blood flow data subjected to frequency analysis, and an ultrasonic diagnostic apparatus as shown in FIG. It is possible to contribute to improvement of diagnostic performance by providing an ultrasonic image from which striped noise caused by fluctuations in the power supply load is removed.
  • the ultrasonic diagnostic apparatus is effective as an ultrasonic diagnostic apparatus for reducing noise caused by a power supply circuit and having an effect that power supply noise is not superimposed on the result of Doppler frequency analysis.
  • Ultrasonic diagnostic device 3 Ultrasonic probe 4 Ultrasonic transmitter / receiver 5 Ultrasonic image forming unit 6 Display unit 7 Control unit 8 Control panel 9 Power supply unit 10 Clock circuit unit

Abstract

This ultrasonic diagnostic device is provided with a control unit for performing control to satisfy the numerical formula below by controlling at least one from among a reference wave frequency (Fref), a switching frequency (Fsw), and a sampling frequency (Fadc), and the ultrasonic diagnostic device removes removal components (for example, clutter components) appearing near the reference wave frequency (Fref) and removes noise. Fref=n*Fsw (n-1)*Fsw≤Fref-(1/2)Fadc Fre+(1/2)Fadc≤(n+1)*Fsw N: positive integer Fref: reference wave frequency Fsw: switching frequency Fadc: Sampling frequency

Description

超音波診断装置及びそのノイズ低減方法Ultrasonic diagnostic apparatus and noise reduction method thereof
　本発明は、超音波診断装置に関し、特に、ノイズを低減する超音波診断装置に関する。 The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that reduces noise.
　近年の電子デバイスでは、製造プロセス微細化により、電子デバイス動作速度の高速化が図られてきた。その結果、瞬時動作電流増大が要求されるため、電子デバイスの近傍にスイッチング電源を配置して瞬時電流供給を可能とする方式が採用されている。 In recent electronic devices, the operation speed of electronic devices has been increased by miniaturizing the manufacturing process. As a result, since an increase in instantaneous operating current is required, a method is adopted in which a switching power supply is arranged in the vicinity of the electronic device to enable instantaneous current supply.
　超音波診断装置でも、CPU、GPU、FPGAなどの演算デバイスの性能向上に伴い、超音波診断装置の小型化が進んでいる。このように、超音波診断装置の小型化が進むと、超音波診断装置内部デバイスの動作周波数高速化が進み、EMIノイズ(電磁放射電波障害ノイズ)の増大や高周波数化が問題となっている。 Also in the ultrasonic diagnostic equipment, miniaturization of the ultrasonic diagnostic equipment is progressing along with the improvement of the performance of arithmetic devices such as CPU, GPU and FPGA. As described above, as the size of the ultrasonic diagnostic apparatus is reduced, the operating frequency of the internal device of the ultrasonic diagnostic apparatus is increased, and the increase in EMI noise (electromagnetic radiation interference noise) and the increase in frequency are problematic. .
　手術室や病室などの患者周辺には、超音波診断装置の他、患者に取り付けられたペースメーカーや脳波計が存在する場合が多く、超音波診断装置が放出したEMIノイズが他機器へ混入し、他機器の誤動作を起こすという問題がある。 There are many pacemakers and electroencephalographs attached to the patient in addition to the ultrasonic diagnostic equipment in the vicinity of the patient such as the operating room and the hospital room, and EMI noise emitted by the ultrasonic diagnostic equipment is mixed into other equipment, There is a problem of causing malfunction of other devices.
　そこで、超音波診断装置のパルス繰り返し周波数に応じて、電源回路のスイッチング周波数を変化させる技術が提案されている(例えば、特許文献1)。 Therefore, a technique for changing the switching frequency of the power supply circuit in accordance with the pulse repetition frequency of the ultrasonic diagnostic apparatus has been proposed (for example, Patent Document 1).
特開平5－130992号公報Japanese Patent Laid-Open No. 5-130992
　しかしながら、特許文献1の発明では、電源回路が発生する低周波ノイズやEMIノイズに関しては十分考慮されていない。また、電源スイッチング周波数がPRF(PulseRepetitionFrequency)に依存する場合、その高調波周波数成分により、EMIノイズの原因となる特定周波数へのエネルギー集中が生じてしまう。 However, in the invention of Patent Document 1, low frequency noise and EMI noise generated by the power supply circuit are not sufficiently considered. In addition, when the power switching frequency depends on PRF (Pulse Repetition Frequency), the harmonic frequency component causes energy concentration to a specific frequency causing EMI noise.
　そこで、本発明は、電源回路に起因するノイズを低減し、パルスドプラ法(PWD)又は連続波ドプラ法(CWD)によるドプラ周波数分析の結果に電源ノイズが重畳しないような超音波診断装置を提供することを目的とする。 Therefore, the present invention provides an ultrasonic diagnostic apparatus that reduces noise caused by a power supply circuit and does not superimpose power supply noise on the result of Doppler frequency analysis by pulse Doppler (PWD) or continuous wave Doppler (CWD). For the purpose.
　本発明の超音波診断装置は、スイッチング周波数を用いて、スイッチング電源部をオン/オフすることにより、電圧を調整する電源部と、参照波周波数を用いて、超音波の受信信号の検波を行う検波部と、サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部とを備える。 The ultrasonic diagnostic apparatus according to the present invention detects a received ultrasonic signal using a reference wave frequency and a power supply unit that adjusts the voltage by turning on and off the switching power supply unit using the switching frequency. A detection unit, an analog signal of the reception signal using a sampling frequency, an A / D conversion unit that converts the reception signal from the analog signal to a digital signal, the reference wave frequency, the switching frequency, and And a control unit that performs control satisfying the following formula by controlling at least one of the sampling frequencies.
　　　　Fref＝n＊Fsw
　　　　(n－1)＊Fsw≦Fref－(1/2)Fadc
　　　　Fref＋(1/2)Fadc≦(n＋1)＊Fsw
　　　　　　N　 ：正の整数
　　　　　　Fref：参照波周波数
　　　　　　Fsw ：スイッチング周波数
　　　　　　Fadc：サンプリング周波数
　この構成によれば、高調波成分と参照波周波数Frefとを一致させ、信号処理領域の範囲内で、その他の高調波成分が存在しないようにすることができ、参照波周波数Frefの近傍に現れる除去成分(例えば、クラッタ成分)とともに、ノイズを除去することができる。 Fref = n * Fsw
(n-1) * Fsw≤Fref- (1/2) Fadc
Fref + (1/2) Fadc≤ (n + 1) * Fsw
N: Positive integer Fref: Reference wave frequency Fsw: Switching frequency Fadc: Sampling frequency According to this configuration, the harmonic component is matched with the reference wave frequency Fref, and other harmonic components are within the signal processing area. Can be eliminated, and noise can be removed together with a removal component (for example, a clutter component) that appears in the vicinity of the reference wave frequency Fref.
　本発明の超音波診断装置は、スイッチング周波数を用いて、スイッチング電源部をオン/オフすることにより、電圧を調整する電源部と、サンプリング周波数を用いて、超音波の受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、前記スイッチング周波数及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部とを備える。 The ultrasonic diagnostic apparatus of the present invention uses a switching frequency to turn on / off the switching power supply unit, and adjusts the voltage, and uses the sampling frequency to sample an analog signal of the ultrasonic reception signal. An A / D converter that converts the received signal from the analog signal to a digital signal, and a controller that performs control that satisfies the following formula by controlling at least one of the switching frequency and the sampling frequency: Is provided.
　　　　Fsw＝n＊(1/2)Fadc
　　　　　　N   ：正の整数
　　　　　　Fsw ：スイッチング周波数
　　　　　　Fadc：サンプリング周波数
　この構成によれば、高調波成分とサンプリング周波数Fadcとを一致させて、高調波成分を除去成分(例えば、クラッタ成分)に重畳させることができ、除去成分とともに、ノイズを除去することができる。 Fsw = n * (1/2) Fadc
N: Positive integer Fsw: Switching frequency Fadc: Sampling frequency According to this configuration, the harmonic component and the sampling frequency Fadc can be matched to superimpose the harmonic component on the removal component (eg, clutter component). The noise can be removed together with the removal component.
　本発明の超音波診断装置は、スイッチング周波数を用いて、スイッチング電源部をオン/オフすることにより、電圧を調整する電源部と、参照波周波数を用いて、超音波の受信信号の検波を行う検波部と、サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部とを備える。 The ultrasonic diagnostic apparatus according to the present invention detects a received ultrasonic signal using a reference wave frequency and a power supply unit that adjusts the voltage by turning on and off the switching power supply unit using the switching frequency. A detection unit, an analog signal of the reception signal using a sampling frequency, an A / D conversion unit that converts the reception signal from the analog signal to a digital signal, the reference wave frequency, the switching frequency, and And a control unit that performs control satisfying the following formula by controlling at least one of the sampling frequencies.
　　　　n＊Fsw≦Fref－(1/2)Fadc
　　　　Fref＋(1/2)Fadc≦(n＋1)＊Fsw
　　　　　　N   ：正の整数
　　　　　　Fref：参照波周波数
　　　　　　Fsw ：スイッチング周波数
　　　　　　Fadc：サンプリング周波数
　この構成によれば、ドプラ信号処理領域の範囲内で、高調波成分が存在しないようにすることができ、参照波周波数Frefの近傍に現れる除去成分(例えば、クラッタ成分)とともに、ノイズを除去することができる。 n * Fsw≤Fref- (1/2) Fadc
Fref + (1/2) Fadc≤ (n + 1) * Fsw
N: Positive integer Fref: Reference wave frequency Fsw: Switching frequency Fadc: Sampling frequency With this configuration, it is possible to prevent the presence of harmonic components within the Doppler signal processing region, and the reference wave frequency Fref Noise can be removed together with a removal component (for example, a clutter component) that appears in the vicinity of.
　本発明の超音波診断装置は、スイッチング周波数を用いて、スイッチング電源部をオン/オフすることにより、電圧を調整する電源部と、分析周波数を用いて、超音波の受信信号を周波数分析する周波数分析部と、前記スイッチング周波数及び前記分析周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部とを備える。 The ultrasonic diagnostic apparatus according to the present invention uses a switching frequency to turn on / off the switching power supply unit, adjusts the voltage, and uses the analysis frequency to frequency-analyze the ultrasonic reception signal. An analysis unit, and a control unit that performs control that satisfies the following formula by controlling at least one of the switching frequency and the analysis frequency.
　　　　Fsw＝n＊(1/2)Fanalyze
　　　　　　N       ：正の整数
　　　　　　Fsw     ：スイッチング周波数
　　　　　　Fanalyze：分析周波数
　この構成によれば、高調波成分と分析周波数Fanalyzeとを一致させて、高調波成分を除去成分(例えば、クラッタ成分)に重畳させることができ、除去成分とともに、ノイズを除去することができる。 Fsw = n * (1/2) Fanalyze
N: positive integer Fsw: switching frequency Fanalyze: analysis frequency According to this configuration, the harmonic component and the analysis frequency Fanalyze can be matched and the harmonic component can be superimposed on the removal component (eg, clutter component). The noise can be removed together with the removal component.
　本発明の超音波診断装置は、前記スイッチング周波数の高調波成分を除去するフィルタ部を備える。 The ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency.
　この構成によれば、除去成分とともに、ノイズを除去することができ、その他の高調波成分も除去することができる。 According to this configuration, noise can be removed together with the removal component, and other harmonic components can also be removed.
　本発明の超音波診断装置では、前記フィルタ部は、前記受信信号のクラッタ成分を除去するフィルタ部と共通である。 In the ultrasonic diagnostic apparatus of the present invention, the filter unit is common to a filter unit that removes clutter components of the received signal.
　この構成によれば、共通のフィルタ部が、除去成分とともに、ノイズを除去することができる。また、共通のフィルタ部により、省スペース化及び低コスト化を図った超音波診断装置を実現することができる。 According to this configuration, the common filter unit can remove noise together with the removal component. Also, an ultrasonic diagnostic apparatus that achieves space saving and cost reduction can be realized by a common filter unit.
　本発明の超音波診断装置は、前記スイッチング周波数の高調波成分を除去するフィルタ部を備え、前記フィルタ部は、前記A/D変換部の前段に設けられる。 The ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency, and the filter unit is provided in front of the A / D conversion unit.
　この構成によれば、アナログCWD処理又はアナログPWD処理に対応することができる。 This configuration can support analog CWD processing or analog PWD processing.
　本発明の超音波診断装置は、前記スイッチング周波数の高調波成分を除去するフィルタ部を備え、前記フィルタ部は、前記A/D変換部の後段に設けられ、前記分析周波数の1/2以上の周波数成分を除去する。 The ultrasonic diagnostic apparatus of the present invention includes a filter unit that removes harmonic components of the switching frequency, and the filter unit is provided at a subsequent stage of the A / D conversion unit and has a frequency equal to or greater than ½ of the analysis frequency. Remove frequency components.
　この構成によれば、HPRF(High Pulse Repetition Frequency)モードに対応することができる。 This configuration is compatible with HPRF (High Pulse Repetition Frequency) mode.
　本発明の超音波診断装置では、前記受信信号は、繰り返して送信された超音波パルスが目的物で反射したドプラ信号である。 In the ultrasonic diagnostic apparatus according to the present invention, the received signal is a Doppler signal in which an ultrasonic pulse transmitted repeatedly is reflected by an object.
　この構成によれば、ドプラ信号に重畳するノイズを低減することができる。 According to this configuration, noise superimposed on the Doppler signal can be reduced.
　本発明のノイズ低減方法は、スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整し、参照波周波数を用いて、超音波の受信信号の検波を行い、サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換し、前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う。 The noise reduction method of the present invention adjusts the voltage by turning on / off the FET of the switching power supply unit using the switching frequency, performs detection of the ultrasonic reception signal using the reference wave frequency, and performs sampling. Sampling an analog signal of the received signal using a frequency, converting the received signal from the analog signal to a digital signal, and controlling at least one of the reference wave frequency, the switching frequency, and the sampling frequency; Thus, control satisfying the following mathematical formula is performed.
　　　　Fref＝n＊Fsw
　　　　(n－1)＊Fsw≦Fref－(1/2)Fadc
　　　　Fref＋(1/2)Fadc≦(n＋1)＊Fsw
　　　　　　N   ：正の整数
　　　　　　Fref：参照波周波数
　　　　　　Fsw ：スイッチング周波数
　　　　　　Fadc：サンプリング周波数
　この構成によれば、高調波成分と参照波周波数Frefとを一致させ、信号処理領域の範囲内で、その他の高調波成分が存在しないようにすることができ、参照波周波数Frefの近傍に現れる除去成分(例えば、クラッタ成分)とともに、ノイズを除去することができる。 Fref = n * Fsw
(n-1) * Fsw≤Fref- (1/2) Fadc
Fref + (1/2) Fadc≤ (n + 1) * Fsw
N: Positive integer Fref: Reference wave frequency Fsw: Switching frequency Fadc: Sampling frequency According to this configuration, the harmonic component is matched with the reference wave frequency Fref, and other harmonic components are within the signal processing area. Can be eliminated, and noise can be removed together with a removal component (for example, a clutter component) that appears in the vicinity of the reference wave frequency Fref.
　本発明は、電源回路に起因するノイズを低減し、ドプラ周波数分析の結果に電源ノイズが重畳しないという効果を有する超音波診断装置を提供することができるものである。 The present invention can provide an ultrasonic diagnostic apparatus that reduces noise caused by a power supply circuit and has an effect that power supply noise is not superimposed on the result of Doppler frequency analysis.
本発明の実施の形態に係る超音波診断装置の一例を示したブロック図1 is a block diagram showing an example of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. スイッチング電源回路の一例を示した図Diagram showing an example of a switching power supply circuit アナログCWD処理又はアナログPWD処理を行う回路の一例を示したブロック図Block diagram showing an example of a circuit that performs analog CWD processing or analog PWD processing (a)受信信号の周波数成分を示した図、(b)スイッチング周波数Fswが100KHzである場合の高調波成分分布を示した図、(c)スイッチング周波数Fswが150KHzである場合の高調波成分分布を示した図(a) Diagram showing frequency component of received signal, (b) Diagram showing harmonic component distribution when switching frequency Fsw is 100 KHz, (c) Harmonic component distribution when switching frequency Fsw is 150 KHz Figure showing スイッチング周波数Fswによって、直交検波後のドプラ成分とスイッチングノイズが重畳するか否かを示した図Figure showing whether or not the Doppler component after quadrature detection and switching noise are superimposed by switching frequency Fsw フィルタ部の通過帯域と周波数分析部の周波数分析範囲を示した図Diagram showing the passband of the filter section and the frequency analysis range of the frequency analysis section スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去された後の高調波成分分布を示した図The figure which showed the harmonic component distribution after the harmonic component of switching frequency Fsw and the low frequency component which accompanies it were removed (a)スイッチング周波数Fswの高調波成分が信号処理領域の範囲内に存在しないことを示した図、(b)スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去されることを示した図(a) Diagram showing that harmonic components of switching frequency Fsw do not exist within the range of the signal processing region, (b) Shows that harmonic components of switching frequency Fsw and the accompanying low frequency components are removed. Figure HPRFモードにおけるアナログCWD処理又はアナログPWD処理を行う回路のブロック図Block diagram of a circuit that performs analog CWD processing or analog PWD processing in HPRF mode (a)受信信号の周波数成分を示した図、(b)分析周波数Fanalyze毎にリサンプルされた結果を示した図(a) The figure which showed the frequency component of the reception signal, (b) The figure which showed the result resampled for every analysis frequency Fanalyze (a)リサンプリング結果にスイッチングノイズが重畳することを示した図、(b)リサンプリング結果にスイッチングノイズが重畳しないことを示した図(a) Diagram showing that switching noise is superimposed on resampling result, (b) Diagram showing that switching noise is not superimposed on resampling result スイッチング時刻に相当する位置に、同心円ノイズが出現することを示した図Diagram showing concentric noise appearing at the position corresponding to the switching time
　以下、本発明の実施の形態の超音波診断装置について、図面を用いて説明する。図1は、本実施の形態に係る超音波診断装置の一例を示すブロック図である。 Hereinafter, an ultrasonic diagnostic apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of an ultrasonic diagnostic apparatus according to the present embodiment.
　図1に示すように、超音波診断装置1は、超音波探触子3を介して被検体2内に超音波を送受信し、受信によって得られたエコー信号を用いて、被検体2の診断部位の2次元超音波画像、3次元超音波画像、及び各種ドプラ画像などを構成して、表示部6にこれらの画像を表示させる。 As shown in FIG. 1, the ultrasonic diagnostic apparatus 1 transmits and receives ultrasonic waves into the subject 2 via the ultrasonic probe 3, and uses the echo signal obtained by reception to diagnose the subject 2. A two-dimensional ultrasonic image of the part, a three-dimensional ultrasonic image, various Doppler images, and the like are formed, and these images are displayed on the display unit 6.
　超音波診断装置1は、超音波探触子3と、超音波送受信部4と、超音波画像形成部5と、表示部6と、制御部7と、コントロールパネル8と、電源部9と、クロック回路部10とを備える。超音波探触子3は、被検体2に超音波を送信し、目的物で反射したエコーを受信する。 The ultrasonic diagnostic apparatus 1 includes an ultrasonic probe 3, an ultrasonic transmission / reception unit 4, an ultrasonic image forming unit 5, a display unit 6, a control unit 7, a control panel 8, a power supply unit 9, And a clock circuit unit 10. The ultrasonic probe 3 transmits ultrasonic waves to the subject 2 and receives echoes reflected by the target object.
　超音波探触子3は、複数の振動子素子をアレイ化して超音波探触子3の長軸方向に1～mチャネル配列された超音波振動部を含み、超音波探触子3は、超音波振動部から被検体2へ超音波を照射する。超音波探触子3は、短冊型振動子を備えるリニアアレイ探触子であってもよく、2次元アレイ探触子であってもよい。 The ultrasonic probe 3 includes an ultrasonic vibration section in which a plurality of transducer elements are arrayed and arranged in 1 to m channels in the longitudinal direction of the ultrasonic probe 3, and the ultrasonic probe 3 Ultrasonic waves are applied to the subject 2 from the ultrasonic vibration unit. The ultrasonic probe 3 may be a linear array probe having a strip type transducer or a two-dimensional array probe.
　超音波送信回路4aは、制御部7の制御に従って、超音波送信信号を生成する。超音波受信回路4bは、超音波探触子3の超音波振動部からの受信信号(例えば、繰り返して送信された超音波パルスが目的物で反射したドプラ信号)を受信し、制御部7の整相遅延制御により、受信信号の整相処理を行う。 The ultrasonic transmission circuit 4a generates an ultrasonic transmission signal according to the control of the control unit 7. The ultrasonic reception circuit 4b receives a reception signal from the ultrasonic vibration unit of the ultrasonic probe 3 (for example, a Doppler signal in which an ultrasonic pulse transmitted repeatedly is reflected by an object), and the control unit 7 The phasing process of the received signal is performed by the phasing delay control.
　超音波画像形成部5は、受信信号から、2次元超音波画像、3次元超音波画像、及び各種ドプラ画像を形成する。表示部6は、超音波画像形成部5で形成された超音波画像を表示する。制御部7は、超音波診断装置1の各要素を制御する。 The ultrasonic image forming unit 5 forms a two-dimensional ultrasonic image, a three-dimensional ultrasonic image, and various Doppler images from the received signal. The display unit 6 displays the ultrasonic image formed by the ultrasonic image forming unit 5. The control unit 7 controls each element of the ultrasonic diagnostic apparatus 1.
　コントロールパネル8は、操作者の操作により制御部7に指示を与える。クロック回路部10は、クロック分周回路10aを備える。クロック分周回路10aは、制御部7の制御に従って、A/D変換回路(A/D変換部)4cのサンプルクロックやスイッチング電源回路(スイッチング電源部)9aのスイッチング信号を生成する。電源部9は、超音波診断装置1に対し、動作するための電力を供給する。電源部9は、電圧を中間電位からデバイスに適した電位電圧へ効率よく昇降圧させるスイッチング電源回路(スイッチング電源部)9aを含む。つまり、電源部9は、スイッチング周波数を用いて、スイッチング電源回路9aのFETをOn/Off(オン/オフ)することにより、電圧を調整する。 The control panel 8 gives an instruction to the control unit 7 by the operation of the operator. The clock circuit unit 10 includes a clock frequency dividing circuit 10a. The clock frequency dividing circuit 10a generates a sample clock of the A / D conversion circuit (A / D conversion unit) 4c and a switching signal of the switching power supply circuit (switching power supply unit) 9a according to the control of the control unit 7. The power supply unit 9 supplies power for operation to the ultrasound diagnostic apparatus 1. The power supply unit 9 includes a switching power supply circuit (switching power supply unit) 9a that efficiently raises and lowers the voltage from an intermediate potential to a potential voltage suitable for the device. That is, the power supply unit 9 adjusts the voltage by turning on / off the FET of the switching power supply circuit 9a using the switching frequency.
　図2は、スイッチング電源回路9aの一例として、降圧型スイッチング電源回路を示したブロック図である。スイッチング電源回路9aは、スイッチング電源コントローラ2-1により、FET1(ハイサイドFET)及びFET2(ローサイドFET)をOn/Off(オン/オフ)させることで、電圧を中間電位からデバイスに適した電位電圧へ効率よく降圧させる。 FIG. 2 is a block diagram showing a step-down switching power supply circuit as an example of the switching power supply circuit 9a. The switching power supply circuit 9a uses the switching power supply controller 2-1 to turn on / off the FET1 (high side FET) and FET2 (low side FET), thereby changing the voltage from the intermediate potential to the potential voltage suitable for the device. Reduce pressure efficiently.
　超音波送受信部4は、超音波送信回路4a、超音波受信回路4b、A/D変換回路4c、及び整相回路4dを備える。超音波送信回路4aは、パルス状の電気信号を発生し、被検体2に送信する超音波信号を発生する。超音波受信回路4bは、超音波探触子3で受信したエコー信号を受信する。A/D変換回路4cは、超音波受信回路4bで受信した受信信号をデジタル信号に変換する。A/D変換回路4cは、サンプリング周波数Fadcを用いて、超音波の受信信号のアナログ信号をサンプリングし、受信信号をアナログ信号からデジタル信号へ変換する。整相回路4dは、受信信号の整相処理を行う。また、超音波送受信部4は、超音波受信回路4bで受信したエコー信号を直交検波して複素信号に変換する複素信号変換部を含む(図示せず)。 The ultrasonic transmission / reception unit 4 includes an ultrasonic transmission circuit 4a, an ultrasonic reception circuit 4b, an A / D conversion circuit 4c, and a phasing circuit 4d. The ultrasonic transmission circuit 4a generates a pulsed electric signal and generates an ultrasonic signal to be transmitted to the subject 2. The ultrasonic receiving circuit 4b receives the echo signal received by the ultrasonic probe 3. The A / D conversion circuit 4c converts the reception signal received by the ultrasonic reception circuit 4b into a digital signal. The A / D conversion circuit 4c samples the analog signal of the ultrasonic reception signal using the sampling frequency Fadc, and converts the reception signal from an analog signal to a digital signal. The phasing circuit 4d performs phasing processing on the received signal. In addition, the ultrasonic transmission / reception unit 4 includes a complex signal conversion unit (not shown) that performs orthogonal detection on the echo signal received by the ultrasonic reception circuit 4b and converts it into a complex signal.
　超音波画像形成部5は、超音波送受信部4の複素信号変換部により変換された複素信号を用いて、超音波断層像を形成する。超音波画像形成部5は、超音波画像情報生成部5a、デジタルスキャンコンバータ部(DSC部)5b、グラフィックデータ生成部5c、合成記憶部5d、及びインターフェイス5eを備える。超音波画像情報生成部5aは、複素信号を用いて検査対象(目的物を含む)の超音波画像情報を生成する。DSC部5bは、生成された超音波画像情報をテレビ表示画像パターンに走査変換して、超音波画像データを生成する。DSC部5bは、超音波受信回路4bの整相処理信号を用いて、超音波画像を表示部6に表示させる。例えば、DSC部5bは、超音波画像であるBモード画像、Mモード画像、ドプラ画像、及び血流画像などを構成し、表示部6に表示させる。 The ultrasonic image forming unit 5 forms an ultrasonic tomographic image using the complex signal converted by the complex signal converting unit of the ultrasonic transmitting / receiving unit 4. The ultrasonic image forming unit 5 includes an ultrasonic image information generation unit 5a, a digital scan converter unit (DSC unit) 5b, a graphic data generation unit 5c, a synthesis storage unit 5d, and an interface 5e. The ultrasonic image information generation unit 5a generates ultrasonic image information of an inspection target (including an object) using a complex signal. The DSC unit 5b scan-converts the generated ultrasonic image information into a television display image pattern, and generates ultrasonic image data. The DSC unit 5b causes the display unit 6 to display an ultrasonic image using the phasing processing signal of the ultrasonic receiving circuit 4b. For example, the DSC unit 5b configures a B-mode image, an M-mode image, a Doppler image, a blood flow image, and the like, which are ultrasonic images, and displays them on the display unit 6.
　グラフィックデータ生成部5cは、DSC部5bにより走査変換されて得られた超音波画像データに基づいて、超音波画像に付帯するためのスケールやマークや文字などのグラフィックデータを生成する。合成記憶部5dは、DSC部5bにより生成された超音波画像データとグラフィックデータ生成部5cにより生成されたグラフィックデータとを合成して記憶する。合成記憶部5dはハードディスクや一時記憶メモリRAMなどを含む。インターフェイス5eは、制御部7の制御命令に基づいて、超音波画像情報生成部5a、DSC部5b、グラフィックデータ生成部5c、及び合成記憶部5dの各種処理に必要な初期値や制御パラメータなどを読み出して、超音波画像情報生成部5a、DSC部5b、グラフィックデータ生成部5c、及び合成記憶部5dに設定する。 The graphic data generation unit 5c generates graphic data such as a scale, a mark, and a character attached to the ultrasonic image based on the ultrasonic image data obtained by the scan conversion by the DSC unit 5b. The synthesis storage unit 5d synthesizes and stores the ultrasonic image data generated by the DSC unit 5b and the graphic data generated by the graphic data generation unit 5c. The composite storage unit 5d includes a hard disk, a temporary storage memory RAM, and the like. Based on the control command of the control unit 7, the interface 5e displays initial values and control parameters required for various processes of the ultrasonic image information generation unit 5a, the DSC unit 5b, the graphic data generation unit 5c, and the synthesis storage unit 5d. It is read out and set in the ultrasonic image information generation unit 5a, the DSC unit 5b, the graphic data generation unit 5c, and the synthesis storage unit 5d.
　表示部6は、超音波画像形成部5で形成された画像を、超音波画像として表示する。表示部6は、例えばCRTモニタや液晶モニタなどを含む。制御部7は、コントロールパネル8からの指示に従って、超音波診断装置1の各構成要素の動作を制御し、ユーザインターフェイス回路(図示せず)とのインターフェイスを有する制御用コンピュータシステムを含む。制御部7は、ユーザインターフェイス回路を制御したり、ユーザインターフェイス回路からの情報に基づいて、超音波送受信部4や超音波画像形成部5などを制御したりする。また、制御部7は、超音波画像形成部5で画像化した情報を表示部6の表示制御部(図示せず)に伝送するための制御を行う。 The display unit 6 displays the image formed by the ultrasonic image forming unit 5 as an ultrasonic image. The display unit 6 includes, for example, a CRT monitor or a liquid crystal monitor. The control unit 7 includes a control computer system that controls the operation of each component of the ultrasonic diagnostic apparatus 1 according to an instruction from the control panel 8 and has an interface with a user interface circuit (not shown). The control unit 7 controls the user interface circuit, and controls the ultrasonic transmission / reception unit 4, the ultrasonic image forming unit 5, and the like based on information from the user interface circuit. Further, the control unit 7 performs control for transmitting information imaged by the ultrasonic image forming unit 5 to a display control unit (not shown) of the display unit 6.
　本実施の形態の超音波診断装置1は、電源部9により生じるEMIノイズやスイッチング電源回路9aにより生じる超音波画像ノイズを低減する。 The ultrasonic diagnostic apparatus 1 according to the present embodiment reduces EMI noise generated by the power supply unit 9 and ultrasonic image noise generated by the switching power supply circuit 9a.
　近年、IC製造技術の進歩に伴い、CPU、GPU、FPGA、及びASICなどのデジタルデバイスの高性能化が図られてきた。具体的には、ICのプロセスが微細化し、その結果、IC内の動作速度が上昇し、IC電源電圧が低下し、デバイス供給電源の瞬時電流が増加した。このような状況下、デバイスの高速動作や瞬時電流変化に対応するために、電源部9がデバイスの近傍に設けられ、中間電位からデバイスに適した電位電圧へ効率よく昇降圧させるスイッチング電源回路9aを用いたPointofLoad(POL)電源供給方式が用いられるようになってきた。 In recent years, with the advancement of IC manufacturing technology, the performance of digital devices such as CPU, GPU, FPGA, and ASIC has been improved. Specifically, the IC process has been miniaturized. As a result, the operating speed in the IC has increased, the IC power supply voltage has decreased, and the instantaneous current of the device supply power has increased. Under such circumstances, in order to cope with the high-speed operation of the device and the instantaneous current change, the power supply unit 9 is provided in the vicinity of the device, and efficiently raises and lowers the voltage from the intermediate potential to the potential voltage suitable for the device. The PointofLoad (POL) power supply method using sapphire has come to be used.
　この方式は、電力変換効率が高いものの、スイッチング周波数Fswに応じた高調波がEMIノイズとして放射し、周辺機器への障害となったり、アナログ信号への廻り込みにより、超音波画像ノイズとなったりする弊害があることが知られている。本実施の形態の超音波診断装置1は、これらのノイズを低減して、超音波診断装置1に適した電源回路方式である。 Although this method has high power conversion efficiency, harmonics corresponding to the switching frequency Fsw are radiated as EMI noise, which may interfere with peripheral devices or become ultrasonic image noise due to wraparound to analog signals. It is known that there are harmful effects. The ultrasonic diagnostic apparatus 1 according to the present embodiment is a power supply circuit system suitable for the ultrasonic diagnostic apparatus 1 by reducing these noises.
　図3は、アナログCWD処理又はアナログPWD処理を行う回路のブロック図である。超音波受信部4の受信信号増幅回路4-1は、受信信号100を増幅する。ミキシング回路(検波部)4-2は、ドプラ変調信号を抽出するために、復調信号生成器4-8から直交検波用の参照波信号(参照波周波数Fref)が入力され、送信周波数に応じた参照波信号を用いて、ドプラデータサンプル位置に応じた位相により受信信号101を直交検波する。 FIG. 3 is a block diagram of a circuit that performs analog CWD processing or analog PWD processing. The reception signal amplification circuit 4-1 of the ultrasonic reception unit 4 amplifies the reception signal 100. A mixing circuit (detection unit) 4-2 receives a reference wave signal (reference wave frequency Fref) for quadrature detection from the demodulated signal generator 4-8 in order to extract a Doppler modulation signal, according to the transmission frequency. Using the reference wave signal, the received signal 101 is quadrature-detected with a phase corresponding to the Doppler data sample position.
　つまり、ミキシング回路(検波部)4-2は、参照波周波数Frefを用いて、超音波の受信信号の検波を行う。チャネル加算回路4-3は、直交検波された受信信号102を加算処理する。ウォールフィルタ(フィルタ部)4-4は、アナログハイパスフィルタ(AHPF)であり、生体の体動に起因する低周波数成分を除去して血流成分信号などを抽出するために、加算処理された受信信号103にフィルタリング処理を行う。アナログアンチエリアシングフィルタ(フィルタ部)4-5は、後段のCW/PW-ADC(A/D変換部)4-6にてエリアシングが起こらないよう、受信信号104のナイキスト周波数以下の信号を通過させる。 That is, the mixing circuit (detection unit) 4-2 detects the ultrasonic reception signal using the reference wave frequency Fref. The channel addition circuit 4-3 performs addition processing on the reception signal 102 subjected to quadrature detection. The wall filter (filter unit) 4-4 is an analog high-pass filter (AHPF), and is added to receive low-frequency components caused by body movement and extract blood flow component signals. A filtering process is performed on the signal 103. The analog anti-aliasing filter (filter unit) 4-5 receives signals below the Nyquist frequency of the received signal 104 so that aliasing does not occur in the subsequent CW / PW-ADC (A / D converter) 4-6. Let it pass.
　CW/PW-ADC(A/D変換部)4-6は、アナログ信号帯域処理を行ったドプラ信号(受信信号105)をCW/PW-ADC変換信号(AD変換クロック)によるサンプリング周波数Fadcでサンプリング処理し、ホールド時間にデジタル信号へ変換する。フィルタリング処理されたアナログドプラ信号には精度よくデジタル信号に変換することが要求され、約16ビット以上のADCが要求されている。このような高精度のADCにおいては、約100KHzから1MHz程度でデジタル信号に変換する方式が、超音波診断装置で用いられている。 The CW / PW-ADC (A / D converter) 4-6 samples the Doppler signal (received signal 105) that has undergone analog signal band processing at the sampling frequency Fadc based on the CW / PW-ADC converted signal (AD conversion clock). Process and convert to digital signal at hold time. The filtered analog Doppler signal is required to be accurately converted to a digital signal, and an ADC of about 16 bits or more is required. In such a high-precision ADC, a method of converting to a digital signal at about 100 KHz to about 1 MHz is used in an ultrasonic diagnostic apparatus.
　デジタル信号に変換されたドプラ信号は、超音波画像情報生成部5aに送信される。超音波画像情報生成部5aのドプラ周波数分析回路(周波数分析部)4-7は、FFTなどの周波数分析方法により周波数分析される。周波数分析されたドプラ信号は、DSC部5bを介して、表示部6に表示される。 The Doppler signal converted into a digital signal is transmitted to the ultrasonic image information generation unit 5a. The Doppler frequency analysis circuit (frequency analysis unit) 4-7 of the ultrasonic image information generation unit 5a performs frequency analysis by a frequency analysis method such as FFT. The Doppler signal subjected to frequency analysis is displayed on the display unit 6 via the DSC unit 5b.
　次に、図4～7を用いて、ノイズが低減される過程について説明する。図4は、連続波ドプラ法(CWD)モード又はパルスドプラ法(PWD)モードにおけるドプラ信号の周波数分析の結果を示す図である。縦軸は信号強度であり、横軸はドプラ信号処理に関する周波数である。ここで、CW/PW-ADC4-6のサンプリング周波数Fadcを、CWDモードでは連続300KHzとし、PWDモードでは超音波送信繰り返しに同期して300KHzとする。 Next, the process of reducing noise will be described with reference to FIGS. FIG. 4 is a diagram illustrating a result of frequency analysis of a Doppler signal in a continuous wave Doppler method (CWD) mode or a pulse Doppler method (PWD) mode. The vertical axis represents signal intensity, and the horizontal axis represents frequency related to Doppler signal processing. Here, the sampling frequency Fadc of the CW / PW-ADC 4-6 is set to 300 KHz continuously in the CWD mode, and 300 KHz in synchronization with repeated ultrasonic transmission in the PWD mode.
　図4(a)は、受信信号の周波数成分を示した図である。図4(a)に示すように、受信信号の周波数成分として、クラッタ成分とドプラ成分(例えば、血流ドプラ成分)が、送受信信号中心周波数(参照波周波数Fref)を中心とするドプラ信号処理領域A“Fref－(1/2)Fadc≦A≦Fref＋(1/2)Fadc”に現れる。クラッタ成分は、呼吸時などにおける臓器の動きに起因する生体組織運動成分であり、信号強度が比較的弱い血流ドプラ信号の検出を妨げるため、ウォールフィルタ(フィルタ部)4-4により除去される。 Fig. 4 (a) shows the frequency components of the received signal. As shown in FIG. 4 (a), as a frequency component of a received signal, a Clutter component and a Doppler component (for example, blood flow Doppler component) are Doppler signal processing regions centered on a transmission / reception signal center frequency (reference wave frequency Fref). A “Fref− (1/2) Fadc ≦ A ≦ Fref + (1/2) Fadc” appears. The clutter component is a biological tissue motion component caused by organ movement during breathing, etc., and is removed by the wall filter (filter unit) 4-4 to prevent detection of a blood flow Doppler signal with a relatively weak signal strength. .
　図4(b)は、スイッチング電源回路9aのスイッチング周波数Fswが100KHzである場合の高調波成分分布を示した図である。 FIG. 4 (b) is a diagram showing the harmonic component distribution when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz.
　図4(c)は、スイッチング電源回路9aのスイッチング周波数Fswが150KHzである場合の高調波成分分布を示した図である。図4(b)に示すように、スイッチング電源回路9aのスイッチング周波数Fswが100KHzである場合、スイッチングノイズが、スイッチング周波数Fsw(100KHz)の正の整数倍(100KHz、200KHz、300KHz・・・・・)に高調波ノイズとして出現する。 FIG. 4 (c) is a diagram showing a harmonic component distribution when the switching frequency Fsw of the switching power supply circuit 9a is 150 KHz. As shown in FIG. 4B, when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz, the switching noise is a positive integer multiple of the switching frequency Fsw (100 KHz) (100 KHz, 200 KHz, 300 KHz ... ) Appears as harmonic noise.
　一方、図4(c)に示すように、スイッチング電源回路9aのスイッチング周波数Fswが150KHzである場合、スイッチングノイズが、スイッチング周波数Fsw(150KHz)の正の整数倍(150KHz、300KHz、450KHz・・・・・)に高調波ノイズとして出現する。また、スイッチング周波数Fswの正の整数倍の近傍に、スペクトラムの拡がりが生じる。これは、超音波診断装置1の電源負荷状態が、超音波送信位置、演算処理内容、演算処理状態、表示状態、及び装置操作状態に応じて、時々刻々と変化するため、スイッチング電源回路9aのFET1及びFET2のOn/Offデューティー比が時々刻々と変化し、その影響が周波数領域で低周波数成分として現れるためである。 On the other hand, as shown in FIG. 4 (c), when the switching frequency Fsw of the switching power supply circuit 9a is 150 kHz, the switching noise is a positive integer multiple of the switching frequency Fsw (150 kHz) (150 kHz, 300 kHz, 450 kHz ...・ ・) Appears as harmonic noise. Further, the spectrum spreads in the vicinity of a positive integer multiple of the switching frequency Fsw. This is because the power supply load state of the ultrasound diagnostic apparatus 1 changes from moment to moment according to the ultrasound transmission position, the contents of the computation process, the computation process state, the display state, and the apparatus operation state. This is because the On / Off duty ratio of FET1 and FET2 changes from moment to moment, and the effect appears as a low frequency component in the frequency domain.
　図5(a)は、スイッチング電源回路9aのスイッチング周波数Fswが100kHzである場合に、直交検波後のドプラ成分とスイッチングノイズが重畳することを示した図である。図5(b)は、スイッチング電源回路9aのスイッチング周波数Fswが150kHzである場合に、直交検波後のドプラ成分とスイッチングノイズが重畳しないことを示した図である。図5(a)(b)に示すように、直交検波後、クラッタ成分とドプラ成分(血流ドプラ成分)が、周波数0の近傍に現れる。 FIG. 5 (a) is a diagram showing that Doppler components after quadrature detection and switching noise are superimposed when the switching frequency Fsw of the switching power supply circuit 9a is 100 kHz. FIG. 5 (b) is a diagram showing that Doppler components after quadrature detection and switching noise do not overlap when the switching frequency Fsw of the switching power supply circuit 9a is 150 kHz. As shown in FIGS. 5 (a) and 5 (b), after the quadrature detection, the clutter component and the Doppler component (blood flow Doppler component) appear in the vicinity of the frequency 0.
　図6(a)は、ウォールフィルタ4-4(アナログハイパスフィルタAHPF)の通過帯域を示した図である。図6(b)は、アナログアンチエリアシングフィルタ(AAF)4-5の通過帯域を示した図である。図6(c)は、CW/PW-ADC4-6のサンプリング周波数Fadcに応じた周波数分析範囲を示した図である。 Fig. 6 (a) shows the passband of the wall filter 4-4 (analog high-pass filter AHPF). FIG. 6 (b) is a diagram showing the passband of the analog anti-aliasing filter (AAF) 4-5. FIG. 6 (c) is a diagram showing a frequency analysis range according to the sampling frequency Fadc of the CW / PW-ADC 4-6.
　図6(a)に示すように、ウォールフィルタ4-4は、アナログハイパスフィルタ(AHPF)であり、クラッタ成分を除去する。また、CW/PW-ADC4-6のサンプリング周波数Fadcは300KHzであるので、ウォールフィルタ4-4のフィルタリング処理により、サンプリング周波数Fadc(300KHz)の正の整数倍におけるスイッチング周波数Fswの高調波成分(300KHz、600KHz、900KHz・・・・・)とそれに付随する低周波成分は除去される。一方、サンプリング周波数Fadc(300KHz)の正の整数倍以外におけるスイッチング周波数Fswの高調波成分とそれに付随する低周波成分は除去されない。 As shown in FIG. 6 (a), the wall filter 4-4 is an analog high-pass filter (AHPF) and removes clutter components. Since the sampling frequency Fadc of CW / PW-ADC4-6 is 300 KHz, the harmonic component (300 KHz) of the switching frequency Fsw at a positive integer multiple of the sampling frequency Fadc (300 KHz) is obtained by the filtering process of the wall filter 4-4. , 600KHz, 900KHz ...) and the accompanying low frequency components are removed. On the other hand, the harmonic component of the switching frequency Fsw and the low frequency component associated therewith other than a positive integer multiple of the sampling frequency Fadc (300 KHz) are not removed.
　したがって、図5(a)に示すように、スイッチング電源回路9aのスイッチング周波数Fswが100KHzである場合、スイッチング周波数Fswの高調波成分(100KHz、200KHz、400KHz、500KHz、700KHz・・・・・)とそれに付随する低周波成分は除去されない。この結果、図6(b)に示すように、CW/PW-ADC4-6のサンプリング周波数Fadc(300KHz)の1/2のカットオフ周波数(150KHz)を通過帯域とするAAF4-5のフィルタリング処理により、カットオフ周波数以上のスイッチング周波数Fswの高調波成分(絶対値が200KHz、400KHz、500KHz、700KHz・・・・・の高調波成分)とそれに付随する低周波成分は除去されるが、絶対値がカットオフ周波数未満のスイッチング周波数Fswの高調波成分(絶対値が100KHzの高調波成分)とそれに付随する低周波成分は除去されない。 Therefore, as shown in FIG. 5 (a), when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz, the harmonic components of the switching frequency Fsw (100 KHz, 200 KHz, 400 KHz, 500 KHz, 700 KHz ...) The accompanying low frequency components are not removed. As a result, as shown in Fig. 6 (b), the filtering process of AAF4-5 with the cut-off frequency (150KHz) half of the sampling frequency Fadc (300KHz) of CW / PW-ADC4-6 as the passband The harmonic component of the switching frequency Fsw above the cut-off frequency (the harmonic component with an absolute value of 200KHz, 400KHz, 500KHz, 700KHz ...) and the accompanying low-frequency component are removed, but the absolute value is The harmonic component of the switching frequency Fsw below the cutoff frequency (the harmonic component having an absolute value of 100 KHz) and the accompanying low frequency component are not removed.
　図7(a)は、スイッチング電源回路9aのスイッチング周波数Fswが100KHzである場合における、ウォールフィルタ(フィルタ部)4-4及びAAF(フィルタ部)4-5のフィルタリング処理により、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去された後の高調波成分分布を示した図である。図7(a)に示すように、CW/PW-ADC4-6のサンプリング周波数(300KHz)の±1/2(±150KHz)の範囲内では、スイッチング周波数Fswの高調波成分(±100KHz)が除去されず、ドプラ成分とスイッチングノイズが重畳する。ドプラ成分とスイッチングノイズが重畳した状態で、超音波画像形成部5により画像化されると、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分に起因するノイズが、表示部6に表示される。 FIG. 7 (a) shows the harmonics of the switching frequency Fsw by the filtering process of the wall filter (filter unit) 4-4 and the AAF (filter unit) 4-5 when the switching frequency Fsw of the switching power supply circuit 9a is 100 KHz. It is the figure which showed the harmonic component distribution after the wave component and the low frequency component accompanying it were removed. As shown in Fig. 7 (a), harmonic components (± 100KHz) of the switching frequency Fsw are removed within the range of ± 1/2 (± 150KHz) of the sampling frequency (300KHz) of CW / PW-ADC4-6. Instead, Doppler components and switching noise are superimposed. When the Doppler component and the switching noise are superimposed and imaged by the ultrasonic image forming unit 5, the noise due to the harmonic component of the switching frequency Fsw and the accompanying low frequency component is displayed on the display unit 6. The
　一方、図5(b)に示すように、スイッチング電源回路9aのスイッチング周波数Fswが150KHzである場合、図6(b)に示すようなCW/PW-ADC4-6のサンプリング周波数(300KHz)の1/2のカットオフ周波数(150KHz)を通過帯域とするAAF4-5のフィルタリング処理により、絶対値がカットオフ周波数以上のスイッチング周波数Fswの高調波成分(絶対値が150KHz、450KHz、750KHz・・・・・の高調波成分)とそれに付随する低周波成分は除去される。 On the other hand, as shown in FIG. 5B, when the switching frequency Fsw of the switching power supply circuit 9a is 150 KHz, 1 of the sampling frequency (300 KHz) of the CW / PW-ADC4-6 as shown in FIG. The harmonic component of the switching frequency Fsw whose absolute value is greater than or equal to the cutoff frequency (Absolute values are 150KHz, 450KHz, 750KHz ... -Harmonic components) and the accompanying low-frequency components are removed.
　図7(b)は、スイッチング電源回路9aのスイッチング周波数が150KHzである場合における、ウォールフィルタ4-4及びAAF4-5のフィルタリング処理により、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去された後の高調波成分分布を示した図である。図7(b)に示すように、CW/PW-ADC4-6のサンプリング周波数Fadc(300KHz)の±1/2(±150KHz)の範囲内では、スイッチング周波数Fswの高調波成分が存在しないので、ドプラ成分とスイッチングノイズが重畳しない。この結果、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分に起因するノイズが低減される。 FIG. 7 (b) shows that when the switching frequency of the switching power supply circuit 9a is 150 KHz, the harmonic component of the switching frequency Fsw and the accompanying low frequency component are obtained by the filtering process of the wall filter 4-4 and AAF4-5. It is the figure which showed the harmonic component distribution after removing. As shown in Fig. 7 (b), the harmonic component of the switching frequency Fsw does not exist within the range of ± 1/2 (± 150 KHz) of the sampling frequency Fadc (300 KHz) of the CW / PW-ADC4-6. Doppler component and switching noise do not overlap. As a result, the noise caused by the harmonic component of the switching frequency Fsw and the accompanying low frequency component is reduced.
　つまり、制御部7が、スイッチング周波数Fswの第1の高調波成分を参照波周波数Frefに一致させるとともに、ドプラ信号の信号処理領域Aの範囲で、スイッチング周波数Fswの第1の高調波成分と異なる高調波成分が存在しないように、参照波周波数Frefとスイッチング周波数Fswとサンプリング周波数Fadcのいずれか1つを制御することにより、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分に起因するノイズが低減される。 That is, the control unit 7 matches the first harmonic component of the switching frequency Fsw to the reference wave frequency Fref, and is different from the first harmonic component of the switching frequency Fsw in the range of the signal processing region A of the Doppler signal. By controlling any one of the reference wave frequency Fref, switching frequency Fsw, and sampling frequency Fadc so that there is no harmonic component, noise caused by the harmonic component of the switching frequency Fsw and the accompanying low frequency component Is reduced.
　本実施の形態では、図4(c)に示すように、スイッチング周波数Fswの高調波成分F1(第1の高調波成分)と参照波周波数Frefとを一致させるため、参照波周波数Frefがスイッチング周波数Fswの正の整数倍(n倍)となるように、制御部7が、参照波周波数Fref及びスイッチング周波数Fswの少なくとも1つを制御する。 In the present embodiment, as shown in FIG. 4 (c), in order to match the harmonic component F1 (first harmonic component) of the switching frequency Fsw with the reference wave frequency Fref, the reference wave frequency Fref is the switching frequency. The control unit 7 controls at least one of the reference wave frequency Fref and the switching frequency Fsw so as to be a positive integer multiple (n times) of Fsw.
　さらに、本実施の形態では、図7(b)に示すように、CW/PW-ADC4-6のサンプリング周波数Fadcの±1/2の範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにするため、図4(c)に示すように、第1の高調波成分F1よりも低周波側に存在する高調波成分F2(第2の高調波成分)の周波数“(n－1)＊Fsw”が、低周波側のドプラ信号処理領域A“Fref－(1/2)Fadc”以下になるように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御する。 Further, in the present embodiment, as shown in FIG. 7 (b), the harmonic component of the switching frequency Fsw does not exist within the range of ± 1/2 of the sampling frequency Fadc of the CW / PW-ADC4-6. Therefore, as shown in FIG. 4 (c), the frequency “(n−1) * of the harmonic component F2 (second harmonic component) existing on the lower frequency side than the first harmonic component F1. The controller 7 controls the control unit 7 so that at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that “Fsw” is equal to or lower than the Doppler signal processing area A “Fref− (1/2) Fadc” on the low frequency side. Control one.
　さらに、本実施の形態では、図7(b)に示すように、CW/PW-ADC4-6のサンプリング周波数Fadcの±1/2の範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにするため、図4(c)に示すように、第1の高調波成分F1よりも高周波側に存在する高調波成分F3(第3の高調波成分)の周波数“(n＋1)＊Fsw”が、高周波側のドプラ信号処理領域A“Fref＋(1/2)Fadc”以上になるように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御する。これらの制御は以下のように数式に表わされる。 Further, in the present embodiment, as shown in FIG. 7 (b), the harmonic component of the switching frequency Fsw does not exist within the range of ± 1/2 of the sampling frequency Fadc of the CW / PW-ADC4-6. Therefore, as shown in FIG. 4 (c), the frequency “(n + 1) * Fsw” of the harmonic component F3 (third harmonic component) existing on the higher frequency side than the first harmonic component F1 is Then, the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that the Doppler signal processing area A on the high frequency side becomes “Fref + (1/2) Fadc” or more. These controls are expressed in mathematical formulas as follows.
　　　　Fref＝n＊Fsw　　　・・・・・(1)
　　　　(n－1)＊Fsw≦Fref－(1/2)Fadc　　　・・・・・(2)
　　　　Fref＋(1/2)Fadc≦(n＋1)＊Fsw　　　・・・・・(3)
　　　　　　　　N   ：正の整数
　　　　　　　　Fref：参照波周波数
　　　　　　　　Fsw ：スイッチング電源回路9aのスイッチング周波数
　　　　　　　　Fadc：CW/PW-ADC4-6のサンプリング周波数
　以上のように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御することで、第1の高調波成分と参照波周波数Frefとを一致させ、ドプラ信号処理領域Aの範囲内で、第2及び第3の高調波成分が存在しないようにすることができる。 Fref = n * Fsw (1)
(n-1) * Fsw≤Fref- (1/2) Fadc (2)
Fref + (1/2) Fadc≤ (n + 1) * Fsw (3)
N: Positive integer Fref: Reference wave frequency Fsw: Switching frequency of switching power supply circuit 9a Fadc: Sampling frequency of CW / PW-ADC4-6 As described above, the control unit 7 controls the reference wave frequency Fref, switching frequency Fsw, By controlling at least one of the sampling frequency Fadc, the first harmonic component and the reference wave frequency Fref are matched, and the second and third harmonic components are within the range of the Doppler signal processing region A. It can be made non-existent.
　この場合、第1の高調波成分がドプラ信号処理領域Aの範囲内(ドプラ信号処理領域Aの中心)に存在することが許容される。この点が、本実施の形態の特徴の1つである。第1の高調波成分は、クラッタ成分とともに、ウォールフィルタ(フィルタ部)4-4により除去される。つまり、スイッチング電源回路9aのFETデューティ比変化により生じた低周波成分を除去するフィルタ部が、超音波の受信信号のクラッタ成分を除去するフィルタ部(ウォールフィルタ4-4)と共通である。また、その他の高調波成分も、AAF(フィルタ部)4-5により除去される。 In this case, the first harmonic component is allowed to exist within the Doppler signal processing region A (center of the Doppler signal processing region A). This is one of the features of this embodiment. The first harmonic component is removed by the wall filter (filter unit) 4-4 together with the clutter component. That is, the filter unit that removes the low-frequency component caused by the FET duty ratio change of the switching power supply circuit 9a is common to the filter unit (wall filter 4-4) that removes the clutter component of the ultrasonic reception signal. Other harmonic components are also removed by the AAF (filter unit) 4-5.
　また、後述するように、スイッチング電源回路9aのスイッチング周波数Fswを大きくして、第1の高調波成分がドプラ信号処理領域Aの範囲内に存在しないようにすることも可能であるが、高速なスイッチング電源回路9aやCW/PW-ADC4-6が要求されるため、消費電力やコストが高くなる。したがって、本実施の形態では、低消費電力で低コストのスイッチング電源回路9aやCW/PW-ADC4-6を使用できる点で有利である。 Further, as will be described later, it is possible to increase the switching frequency Fsw of the switching power supply circuit 9a so that the first harmonic component does not exist within the range of the Doppler signal processing region A. Since the switching power supply circuit 9a and the CW / PW-ADC 4-6 are required, power consumption and cost are increased. Therefore, this embodiment is advantageous in that the switching power supply circuit 9a and the CW / PW-ADC 4-6 with low power consumption and low cost can be used.
　また、上記はアナログCWDモードに関する説明であるが、アナログPWDモードでも同様の動作及び制御を行うことにより、ノイズが低減された超音波画像を実現することができる。特に、アナログPWDモードでは、超音波送信タイミングに同期して、CW/PW-ADC4-6のサンプルクロック及びスイッチング電源回路9aのスイッチング信号が、クロック分周回路10aにより生成される。 In addition, the above description is about the analog CWD mode, but an ultrasonic image with reduced noise can be realized by performing the same operation and control in the analog PWD mode. In particular, in the analog PWD mode, the clock dividing circuit 10a generates the sample clock of the CW / PW-ADC 4-6 and the switching signal of the switching power supply circuit 9a in synchronization with the ultrasonic transmission timing.
　以上、本発明にかかる実施の形態について説明したが、本発明はこれらに限定されるものではなく、請求項に記載された範囲内において変更・変形することが可能である。 As mentioned above, although embodiment concerning this invention was described, this invention is not limited to these, It is possible to change and change within the range described in the claim.
　ドプラ信号処理領域Aの範囲内で、第2及び第3の高調波成分が存在しないようにするために、上記の数式に代えて、以下の数式を満たすように、制御部7が、スイッチング周波数Fsw及びサンプリング周波数Fadcの少なくとも1つを制御してもよい。 In order to prevent the second and third harmonic components from being present within the Doppler signal processing region A, the control unit 7 changes the switching frequency so as to satisfy the following equation instead of the above equation: At least one of Fsw and sampling frequency Fadc may be controlled.
　　　　Fsw＝n＊(1/2)Fadc　　　・・・・・(4)
　　　　　　　　N   ：正の整数
　　　　　　　　Fsw ：スイッチング電源回路9aのスイッチング周波数
　　　　　　　　Fadc：CW/PW-ADC4-6のサンプリング周波数
　例えば、CW/PW-ADC4-6のサンプリング周波数Fadcは300KHzである場合、スイッチング周波数Fswを150KHzの正の整数倍(n倍)となるように、制御部7が、サンプリング周波数Fadc及びスイッチング周波数Fswの少なくとも1つを制御する。 Fsw = n * (1/2) Fadc (4)
N: positive integer Fsw: switching frequency of switching power supply circuit 9a Fadc: sampling frequency of CW / PW-ADC4-6 For example, when sampling frequency Fadc of CW / PW-ADC4-6 is 300KHz, switching frequency Fsw is 150KHz The control unit 7 controls at least one of the sampling frequency Fadc and the switching frequency Fsw so as to be a positive integer multiple (n times).
　n＝1(Fsw＝150KHz)である場合は、図4(c)と同様のスイッチング周波数Fswの高調波成分が現れる。この場合、図5(b)に示すように、直交検波後のドプラ成分とスイッチングノイズが重畳せず、図7(b)に示すように、ウォールフィルタ(フィルタ部)4-4及びAAF(フィルタ部)4-5のフィルタリング処理により、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去される。 When n = 1 (Fsw = 150 KHz), a harmonic component of the switching frequency Fsw similar to that in FIG. 4C appears. In this case, as shown in FIG.5 (b), the Doppler component after quadrature detection and the switching noise do not overlap, and as shown in FIG.7 (b), the wall filter (filter unit) 4-4 and the AAF (filter Part) 4-5, the harmonic component of the switching frequency Fsw and the accompanying low-frequency component are removed.
　上記と同様、この場合も、高調波成分(スイッチングノイズ)は、クラッタ成分とともに、クラッタ成分とともに、ウォールフィルタ(フィルタ部)4-4とAAF(フィルタ部)4-5により除去される。つまり、スイッチング周波数の高調波成分を除去するフィルタ部が、超音波の受信信号のクラッタ成分を除去するフィルタ部(ウォールフィルタ4-4)と共通である。また、その他の高調波成分も、AAF(フィルタ部)4-5により除去される。 Similarly to the above, also in this case, the harmonic component (switching noise) is removed together with the clutter component by the wall filter (filter unit) 4-4 and the AAF (filter unit) 4-5 together with the clutter component. That is, the filter unit that removes the harmonic component of the switching frequency is common to the filter unit (wall filter 4-4) that removes the clutter component of the ultrasonic reception signal. Other harmonic components are also removed by the AAF (filter unit) 4-5.
　以上のように、制御部7が、スイッチング周波数Fsw及びサンプリング周波数Fadcの少なくとも1つを制御することで、第1の高調波成分と参照波周波数Frefとを一致させ、ドプラ信号処理領域Aの範囲内で、第2及び第3の高調波成分が存在しないようにすることができる。 As described above, the control unit 7 controls at least one of the switching frequency Fsw and the sampling frequency Fadc, thereby matching the first harmonic component and the reference wave frequency Fref, and the range of the Doppler signal processing region A. In which the second and third harmonic components can be absent.
　また、ドプラ信号処理領域Aの範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにするために、上記の数式に代えて、以下の数式を満たすように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御してもよい。 Further, in order to prevent the harmonic component of the switching frequency Fsw from being present within the Doppler signal processing region A, the control unit 7 replaces the above equation with the reference wave so as to satisfy the following equation: At least one of the frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc may be controlled.
　　　　n＊Fsw≦Fref－(1/2)Fadc　　　・・・・・(5)
　　　　Fref＋(1/2)Fadc≦(n＋1)＊Fsw　　　・・・・・(6)
　　　　　　　　N   ：正の整数
　　　　　　　　Fref：参照波周波数
　　　　　　　　Fsw ：スイッチング電源回路9aのスイッチング周波数
　　　　　　　　Fadc：CW/PW-ADC4-6のサンプリング周波数
　図8(a)は、スイッチング周波数Fswの高調波成分がドプラ信号処理領域Aの範囲内に存在しないことを示した図である。図8(a)に示すように、送受信信号中心周波数(参照波周波数)Frefよりも低周波側に存在する高調波成分F4(第4の高調波成分)の周波数“n＊Fsw”が、低周波側のドプラ信号処理領域A“Fref－(1/2)Fadc”以下になるように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御する。また、送受信信号中心周波数(参照波周波数)Frefよりも高周波側に存在する高調波成分F5(第5の高調波成分)の周波数“(n＋1)＊Fsw”が、高周波側のドプラ信号処理領域A“Fref＋(1/2)Fadc”以上になるように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御する。 n * Fsw≤Fref- (1/2) Fadc (5)
Fref + (1/2) Fadc≤ (n + 1) * Fsw (6)
N: Positive integer Fref: Reference wave frequency Fsw: Switching frequency of switching power supply circuit 9a Fadc: Sampling frequency of CW / PW-ADC4-6 Figure 8 (a) shows the harmonic component of switching frequency Fsw in the Doppler signal processing region FIG. 6 is a diagram showing that the data does not exist within the range of A. As shown in FIG. 8 (a), the frequency “n * Fsw” of the harmonic component F4 (fourth harmonic component) existing on the lower frequency side than the transmission / reception signal center frequency (reference wave frequency) Fref is low. The control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so that the frequency side Doppler signal processing area A becomes “Fref− (1/2) Fadc” or less. Further, the frequency “(n + 1) * Fsw” of the harmonic component F5 (fifth harmonic component) existing on the high frequency side from the transmission / reception signal center frequency (reference wave frequency) Fref is the high frequency side Doppler signal processing area A. The control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc so as to be equal to or higher than “Fref + (1/2) Fadc”.
　例えば、CW/PW-ADC4-6のサンプリング周波数Fadcが300KHzで、参照波周波数Frefが3MHz(3000KHz)である場合、スイッチング周波数Fswを400KHzとすれば、“2800(n＝8)KHz≦2850(＝3000－300/2)MHz”及び“3150(＝3000＋300/2)≦3200(n＝9)KHz”となり、ドプラ信号処理領域Aの範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにすることができる。この場合、図8(b)に示すように、ウォールフィルタ4-4及びAAF4-5のフィルタリング処理により、スイッチング周波数Fswの高調波成分とそれに付随する低周波成分が除去される。 For example, if the sampling frequency Fadc of the CW / PW-ADC4-6 is 300 KHz and the reference wave frequency Fref is 3 MHz (3000 KHz), if the switching frequency Fsw is 400 KHz, “2800 (n = 8) KHz ≦ 2850 ( = 3000−300 / 2) MHz ”and“ 3150 (= 3000 + 300/2) ≦ 3200 (n = 9) KHz ”, so that there is no harmonic component of the switching frequency Fsw within the Doppler signal processing area A. Can be. In this case, as shown in FIG. 8 (b), the harmonic component of the switching frequency Fsw and the accompanying low-frequency component are removed by the filtering process of the wall filter 4-4 and the AAF 4-5.
　以上のように、制御部7が、参照波周波数Fref、スイッチング周波数Fsw、及びサンプリング周波数Fadcの少なくとも1つを制御することで、ドプラ信号処理領域Aの範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにすることができる。ただし、ドプラ信号処理領域Aの範囲内で、スイッチング周波数Fswの高調波成分が存在しないようにするためには、図8(a)に示すように、ドプラ信号処理領域Aの周波数よりも大きいスイッチング周波数Fswが要求されるので、高速なスイッチング電源回路9aやCW/PW-ADC4-6が要求される。 As described above, the control unit 7 controls at least one of the reference wave frequency Fref, the switching frequency Fsw, and the sampling frequency Fadc, so that the harmonic component of the switching frequency Fsw is within the range of the Doppler signal processing region A. Can be absent. However, in order to prevent the harmonic component of the switching frequency Fsw from being present within the range of the Doppler signal processing area A, switching larger than the frequency of the Doppler signal processing area A as shown in FIG. Since the frequency Fsw is required, a high-speed switching power supply circuit 9a and CW / PW-ADC4-6 are required.
　本発明は、超音波診断装置1のHPRF(High Pulse Repetition Frequency)モードにも適用できる。HPRFモードによるHPRFドップラー法は、目的物深度の反射波が戻ってくる前に強制的に次のパルスが送信されるので、PRF(Pulse Repetition Frequency)を高くでき、高速血流などに対応できる。この場合、デジタル信号に変換されたドプラ信号(ドプラ受信信号)がフィルタリング処理される。 The present invention can also be applied to the HPRF (High Pulse Repetition Frequency) mode of the ultrasonic diagnostic apparatus 1. In the HPRF Doppler method in the HPRF mode, since the next pulse is forcibly transmitted before the reflected wave of the target depth returns, the PRF (Pulse Repetition Frequency) can be increased and high-speed blood flow can be handled. In this case, the Doppler signal (Doppler reception signal) converted into a digital signal is subjected to filtering processing.
　図9は、HPRFモードにおけるデジタルCWD処理又はデジタルPWD処理を行う回路のブロック図である。図3と異なる点は、増幅されたアナログ信号(受信信号101)が、ADC(A/D変換部)4-16により、チャネル毎にデジタル信号に変換され(受信信号1002)、デジタル信号として、デジタルミキシング回路4-12により直交検波され(受信信号1102)、チャネル加算器4-13により整相加算される点である。 FIG. 9 is a block diagram of a circuit that performs digital CWD processing or digital PWD processing in the HPRF mode. The difference from FIG. 3 is that the amplified analog signal (received signal 101) is converted into a digital signal for each channel by ADC (A / D converter) 4-16 (received signal 1002), and as a digital signal, A quadrature detection is performed by the digital mixing circuit 4-12 (received signal 1102), and a phasing addition is performed by the channel adder 4-13.
　ADC(A/D変換部)4-16は、サンプリング周波数Fadcを用いて、超音波の受信信号のアナログ信号をサンプリングし、受信信号をアナログ信号からデジタル信号へ変換する。ADC4-16は、受信信号中心周波数の2倍以上のサンプリングレートを用いて(例えば、約2MHz以上のサンプリング周波数Fadc)、受信信号101をデジタル変換する。チャネル加算器4-13は、直交検波用の参照波信号(参照波周波数Fref)と整相加算された受信信号とをデジタル的に乗算して、ドプラ復調信号を取り出す(受信信号1103)。ここで、チャネル加算器4-13は、ヘテロダイン方式のように、デジタル変換された受信信号1002に対して、チャネル毎に参照波信号をデジタル的に乗算し、不要な高周波成分を除去した後、ベースライン情報として、整相加算してもよい。 ADC (A / D converter) 4-16 samples the analog signal of the ultrasonic reception signal using the sampling frequency Fadc, and converts the reception signal from an analog signal to a digital signal. The ADC 4-16 digitally converts the received signal 101 using a sampling rate that is at least twice the center frequency of the received signal (for example, a sampling frequency Fadc of about 2 MHz or higher). The channel adder 4-13 digitally multiplies the reference wave signal for quadrature detection (reference wave frequency Fref) and the reception signal subjected to phasing addition to extract a Doppler demodulated signal (reception signal 1103). Here, the channel adder 4-13, as in the heterodyne method, digitally multiplies the received signal 1002 converted digitally by a reference wave signal for each channel, and removes unnecessary high frequency components. As the baseline information, phasing addition may be performed.
　デジタル的に復調処理されたドプラ復調信号は、チャンネル加算処理の後、必要なドプラ信号を抽出するため、デジタルフィルタ4-14に入力され、信号処理される。デジタルフィルタ4-14としては、FIRやIIRやIFFTなどの適切なフィルタが用いられればよい。デジタルフィルタ4-14は、心臓壁運動などの低速生体運動に起因する低周波成分(クラッタ成分)を除去する。さらに、デジタルフィルタ4-14は、ドプラ周波数分析回路4-7(周波数分析部)がドプラ信号を周波数分析するための分析周波数(Fanalyze)の1/2以上の周波数成分を除去する。分析周波数Fanalyzeは、超音波診断装置1のPRFと異なってもよい。特に、HPRFモードでは、分析周波数Fanalyzeは、超音波診断装置1のPRFと異なってもよい。 The digitally demodulated Doppler demodulated signal is input to the digital filter 4-14 and subjected to signal processing in order to extract a necessary Doppler signal after channel addition processing. As the digital filter 4-14, an appropriate filter such as FIR, IIR or IFFT may be used. The digital filter 4-14 removes a low frequency component (clutter component) caused by low-speed biological motion such as heart wall motion. Further, the digital filter 4-14 removes frequency components that are 1/2 or more of the analysis frequency (Fanalyze) for the Doppler frequency analysis circuit 4-7 (frequency analysis unit) to analyze the frequency of the Doppler signal. The analysis frequency Fanalyze may be different from the PRF of the ultrasonic diagnostic apparatus 1. In particular, in the HPRF mode, the analysis frequency Fanalyze may be different from the PRF of the ultrasonic diagnostic apparatus 1.
　ドプラ周波数分析回路4-7は、FFTなどの周波数分析方法により、分析周波数Fanalyzeに基づいて、ドプラ信号を周波数分析する。周波数分析されたドプラ信号は、DSC部5bを介して、表示部6に表示される。 The Doppler frequency analysis circuit 4-7 performs frequency analysis of the Doppler signal based on the analysis frequency Fanalyze by a frequency analysis method such as FFT. The Doppler signal subjected to frequency analysis is displayed on the display unit 6 via the DSC unit 5b.
　次に、図10及び図11を用いて、ノイズが低減される過程について説明する。図10(a)は、図4(a)と同様、受信信号の周波数成分を示した図である。図10(a)に示すように、受信信号の周波数成分として、クラッタ成分とドプラ成分(例えば、血流ドプラ成分)が、送受信信号中心周波数(参照波周波数Fref)を中心として現れる。 Next, the process of reducing noise will be described with reference to FIGS. FIG. 10 (a) is a diagram showing frequency components of the received signal, as in FIG. 4 (a). As shown in FIG. 10 (a), as a frequency component of the received signal, a clutter component and a Doppler component (for example, a blood flow Doppler component) appear around the transmission / reception signal center frequency (reference wave frequency Fref).
　図10(b)は、ADC4-16により、分析周波数Fanalyze毎にリサンプルされた結果を示した図である。図10(b)に示すように、ドプラ周波数分析回路4-7が、分析周波数Fanalyze毎(1＊Fanalyze、2＊Fanalyze、3＊Fanalyze、4＊Fanalyze、5＊Fanalyze・・・・・)にリサンプルを行う。図11(a)は、リサンプリング結果にスイッチングノイズが重畳することを示した図である。 FIG. 10 (b) is a diagram showing the result of re-sampling by the ADC 4-16 for each analysis frequency Fanalyze. As shown in Fig. 10 (b), the Doppler frequency analysis circuit 4-7 operates at each analysis frequency Fanalyze (1 * Fanalyze, 2 * Fanalyze, 3 * Fanalyze, 4 * Fanalyze, 5 * Fanalyze ...). Resample. FIG. 11 (a) is a diagram showing that switching noise is superimposed on the resampling result.
　図11(b)は、リサンプリング結果にスイッチングノイズが重畳しないことを示した図である。図11(a)と比較して、図11(b)に示すように、スイッチング周波数Fswが、ドプラ周波数分析回路4-7の分析周波数Fanalyzeの1/2の正の整数倍(n倍)である場合は、クラッタ成分にスイッチングノイズが重畳する。クラッタ成分に重畳したスイッチングノイズは、クラッタ成分とともに、デジタルフィルタ4-14により除去されるので、ドプラ周波数分析回路4-7のリサンプリング結果にスイッチングノイズが重畳しない。 FIG. 11 (b) shows that switching noise is not superimposed on the resampling result. Compared to FIG. 11 (a), as shown in FIG. 11 (b), the switching frequency Fsw is a positive integer multiple (n times) 1/2 of the analysis frequency Fanalyze of the Doppler frequency analysis circuit 4-7. In some cases, switching noise is superimposed on the clutter component. Since the switching noise superimposed on the clutter component is removed together with the clutter component by the digital filter 4-14, the switching noise is not superimposed on the resampling result of the Doppler frequency analysis circuit 4-7.
　このように、リサンプリング結果にスイッチングノイズが重畳しないようにするために、以下の数式を満たすように、制御部7が、スイッチング周波数Fsw及び分析周波数Fanalyzeの少なくとも1つを制御してもよい。つまり、制御部7が、ドプラ周波数分析回路(周波数分析部)4-7のリサンプリング結果にスイッチングノイズが重畳しないように、スイッチング周波数Fswと分析周波数Fanalyzeのいずれか1つを制御する。 Thus, in order to prevent the switching noise from being superimposed on the resampling result, the control unit 7 may control at least one of the switching frequency Fsw and the analysis frequency Fanalyze so as to satisfy the following formula. That is, the control unit 7 controls one of the switching frequency Fsw and the analysis frequency Fanalyze so that switching noise is not superimposed on the resampling result of the Doppler frequency analysis circuit (frequency analysis unit) 4-7.
　　　　Fsw＝n＊(1/2)Fanalyze　　　・・・・・(7)
　　　　　　　　N       ：正の整数
　　　　　　　　Fsw     ：スイッチング電源回路9aのスイッチング周波数
　　　　　　　　Fanalyze：ドプラ周波数分析回路4-7の分析周波数
　以上のように、制御部7が、スイッチング周波数Fsw及び分析周波数Fanalyzeの少なくとも1つを制御することで、ドプラ周波数分析回路4-7のリサンプリング結果にスイッチングノイズが重畳しないようにすることができる。 Fsw = n * (1/2) Fanalyze (7)
N: positive integer Fsw: switching frequency of switching power supply circuit 9a Fanalyze: analysis frequency of Doppler frequency analysis circuit 4-7 As described above, the control unit 7 controls at least one of the switching frequency Fsw and the analysis frequency Fanalyze. Thus, switching noise can be prevented from being superimposed on the resampling result of the Doppler frequency analysis circuit 4-7.
　上記と同様、この場合も、高調波成分(スイッチングノイズ)は、クラッタ成分とともに、デジタルフィルタ(フィルタ部)4-14により除去される。つまり、スイッチング周波数の高調波成分を除去するフィルタ部が、超音波の受信信号のクラッタ成分を除去するフィルタ部(デジタルフィルタ4-14)と共通である。共通のフィルタ部が、除去成分(例えば、クラッタ成分)とともに、スイッチングノイズを除去することができる。また、共通のフィルタ部により、省スペース化及び低コスト化を図った超音波診断装置を実現することができる。 Similarly to the above, in this case, the harmonic component (switching noise) is removed together with the clutter component by the digital filter (filter unit) 4-14. That is, the filter unit that removes the harmonic component of the switching frequency is the same as the filter unit (digital filter 4-14) that removes the clutter component of the ultrasonic reception signal. The common filter unit can remove switching noise together with a removal component (for example, a clutter component). Also, an ultrasonic diagnostic apparatus that achieves space saving and cost reduction can be realized by a common filter unit.
　以上、本発明の実施の形態によれば、ドプラ信号へ混入するスイッチングノイズを低減することができる。アナログCWDモード又はアナログPWDモードの場合、スイッチング電源回路9aのスイッチングノイズが、フィルタリング処理により除去される。また、ドプラ信号処理領域Aにスイッチング電源回路9aのスイッチングノイズが生じないように制御される。この結果、本発明の実施の形態によれば、ドプラ信号にスイッチングノイズが重畳しないので、周波数分析された血流データからスイッチングノイズを除去することができ、図12に示すような超音波診断装置の電源負荷変動に起因する縞状ノイズが除去された超音波画像を提供することで診断性能向上に貢献することができる。 As described above, according to the embodiment of the present invention, the switching noise mixed in the Doppler signal can be reduced. In the analog CWD mode or the analog PWD mode, the switching noise of the switching power supply circuit 9a is removed by the filtering process. In addition, the switching power supply circuit 9a is controlled so as not to generate switching noise in the Doppler signal processing area A. As a result, according to the embodiment of the present invention, since switching noise is not superimposed on the Doppler signal, switching noise can be removed from blood flow data subjected to frequency analysis, and an ultrasonic diagnostic apparatus as shown in FIG. It is possible to contribute to improvement of diagnostic performance by providing an ultrasonic image from which striped noise caused by fluctuations in the power supply load is removed.
　本発明にかかる超音波診断装置は、電源回路に起因するノイズを低減し、ドプラ周波数分析の結果に電源ノイズが重畳しないという効果を有し、ノイズを低減する超音波診断装置として有用である。 The ultrasonic diagnostic apparatus according to the present invention is effective as an ultrasonic diagnostic apparatus for reducing noise caused by a power supply circuit and having an effect that power supply noise is not superimposed on the result of Doppler frequency analysis.
　1　超音波診断装置、3　超音波探触子、4　超音波送受信部、5　超音波画像形成部、6　表示部、7　制御部、8　コントロールパネル、9　電源部、10　クロック回路部 1 Ultrasonic diagnostic device 3 Ultrasonic probe 4 Ultrasonic transmitter / receiver 5 Ultrasonic image forming unit 6 Display unit 7 Control unit 8 Control panel 9 Power supply unit 10 Clock circuit unit

Claims (12)

  1. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　参照波周波数を用いて、超音波の受信信号の検波を行う検波部と、
    　サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、
    　前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部と
    　を備えることを特徴とする超音波診断装置。
    Fref ＝ n ＊ Fsw
    (n－1)＊Fsw ≦ Fref － (1/2)Fadc
    Fref + (1/2)Fadc ≦ (n+1)＊Fsw
    n：正の整数
    Fref：参照波周波数
    Fsw：スイッチング周波数
    Fadc：サンプリング周波数     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    A detection unit for detecting an ultrasonic reception signal using a reference wave frequency;
    Samples the analog signal of the received signal using a sampling frequency, and converts the received signal from the analog signal to a digital signal; and
    An ultrasonic diagnostic apparatus comprising: a control unit that performs control satisfying the following formula by controlling at least one of the reference wave frequency, the switching frequency, and the sampling frequency.
    Fref = n * Fsw
    (n-1) * Fsw ≤ Fref-(1/2) Fadc
    Fref + (1/2) Fadc ≤ (n + 1) * Fsw
    n: positive integer
    Fref: Reference wave frequency
    Fsw: Switching frequency
    Fadc: Sampling frequency
  2. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　サンプリング周波数を用いて、超音波の受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、
    　前記スイッチング周波数及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部と
    　を備えることを特徴とする超音波診断装置。
    Fsw ＝ n＊(1/2)Fadc
    n：正の整数
    Fsw：スイッチング周波数
    Fadc：サンプリング周波数     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    An analog signal of an ultrasonic reception signal is sampled using a sampling frequency, and the A / D conversion unit converts the reception signal from the analog signal to a digital signal.
    An ultrasonic diagnostic apparatus comprising: a control unit that performs control satisfying the following formula by controlling at least one of the switching frequency and the sampling frequency.
    Fsw = n * (1/2) Fadc
    n: positive integer
    Fsw: Switching frequency
    Fadc: Sampling frequency
  3. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　参照波周波数を用いて、超音波の受信信号の検波を行う検波部と、
    　サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、
    　前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部と
    　を備えることを特徴とする超音波診断装置。
    n＊Fsw ≦ Fref － (1/2)Fadc
    Fref + (1/2)Fadc ≦ (n+1)＊Fsw
    n：正の整数
    Fref：参照波周波数
    Fsw：スイッチング周波数
    Fadc：サンプリング周波数     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    A detection unit for detecting an ultrasonic reception signal using a reference wave frequency;
    Samples the analog signal of the received signal using a sampling frequency, and converts the received signal from the analog signal to a digital signal; and
    An ultrasonic diagnostic apparatus comprising: a control unit that performs control satisfying the following formula by controlling at least one of the reference wave frequency, the switching frequency, and the sampling frequency.
    n * Fsw ≤ Fref-(1/2) Fadc
    Fref + (1/2) Fadc ≤ (n + 1) * Fsw
    n: positive integer
    Fref: Reference wave frequency
    Fsw: Switching frequency
    Fadc: Sampling frequency
  4. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　分析周波数を用いて、超音波の受信信号を周波数分析する周波数分析部と、
    　前記スイッチング周波数及び前記分析周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行う制御部と
    　を備えることを特徴とする超音波診断装置。
    Fsw ＝ n＊(1/2)Fanalyze
    n：正の整数
    Fsw：スイッチング周波数
    Fanalyze：分析周波数     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    A frequency analysis unit for analyzing the frequency of the received ultrasonic signal using the analysis frequency;
    An ultrasonic diagnostic apparatus comprising: a control unit that performs control satisfying the following formula by controlling at least one of the switching frequency and the analysis frequency.
    Fsw = n * (1/2) Fanalyze
    n: positive integer
    Fsw: Switching frequency
    Fanalyze: Analysis frequency
  5. 　前記スイッチング周波数の高調波成分を除去するフィルタ部を備えることを特徴とする請求項1乃至4の何れか1つに記載の超音波診断装置。 The ultrasonic diagnostic apparatus according to any one of claims 1 to 4, further comprising a filter unit that removes harmonic components of the switching frequency.
  6. 　前記フィルタ部は、前記受信信号のクラッタ成分を除去するフィルタ部と共通であることを特徴とする請求項5に記載の超音波診断装置。 6. The ultrasonic diagnostic apparatus according to claim 5, wherein the filter unit is common to a filter unit that removes a clutter component of the received signal.
  7. 　前記スイッチング周波数の高調波成分を除去するフィルタ部を備え、
    　前記フィルタ部は、前記A/D変換部の前段に設けられることを特徴とする請求項1乃至3の何れか1つに記載の超音波診断装置。     A filter unit for removing harmonic components of the switching frequency;
    4. The ultrasonic diagnostic apparatus according to claim 1, wherein the filter unit is provided upstream of the A / D conversion unit.
  8. 　前記スイッチング周波数の高調波成分を除去するフィルタ部を備え、
    　前記フィルタ部は、前記分析周波数の1/2以上の周波数成分を除去することを特徴とする請求項4に記載の超音波診断装置。     A filter unit for removing harmonic components of the switching frequency;
    5. The ultrasonic diagnostic apparatus according to claim 4, wherein the filter unit removes a frequency component that is 1/2 or more of the analysis frequency.
  9. 　前記受信信号は、繰り返して送信された超音波パルスが目的物で反射したドプラ信号であることを特徴とする請求項1乃至4の何れか1つに記載の超音波診断装置。 5. The ultrasonic diagnostic apparatus according to claim 1, wherein the received signal is a Doppler signal in which an ultrasonic pulse transmitted repeatedly is reflected by an object.
  10. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　参照波周波数を用いて、超音波の受信信号の検波を行う検波部と、
    　サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換するA/D変換部と、
    　前記スイッチング周波数の第1の高調波成分を前記参照波周波数に一致させるとともに、ドプラ信号の信号処理領域の範囲で、前記スイッチング周波数の前記第1の高調波成分と異なる高調波成分が存在しないように、前記参照波周波数と前記スイッチング周波数と前記サンプリング周波数の少なくとも1つを制御する制御部と
    　を備えることを特徴とする超音波診断装置。     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    A detection unit for detecting an ultrasonic reception signal using a reference wave frequency;
    Samples the analog signal of the received signal using a sampling frequency, and converts the received signal from the analog signal to a digital signal; and
    The first harmonic component of the switching frequency is matched with the reference wave frequency, and there is no harmonic component different from the first harmonic component of the switching frequency in the range of the signal processing region of the Doppler signal. The ultrasonic diagnostic apparatus further comprising: a control unit that controls at least one of the reference wave frequency, the switching frequency, and the sampling frequency.
  11. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整する電源部と、
    　分析周波数を用いて、超音波の受信信号を周波数分析する周波数分析部と、
    　前記周波数分析部のリサンプリング結果にスイッチングノイズが重畳しないように、前記スイッチング周波数と前記分析周波数の少なくとも1つを制御する制御部と
    　を備えることを特徴とする超音波診断装置。     Using the switching frequency, the power supply unit that adjusts the voltage by turning on / off the FET of the switching power supply unit,
    A frequency analysis unit for analyzing the frequency of the received ultrasonic signal using the analysis frequency;
    An ultrasonic diagnostic apparatus comprising: a control unit that controls at least one of the switching frequency and the analysis frequency so that switching noise is not superimposed on a resampling result of the frequency analysis unit.
  12. 　スイッチング周波数を用いて、スイッチング電源部のFETをオン/オフすることにより、電圧を調整し、
    　参照波周波数を用いて、超音波の受信信号の検波を行い、
    　サンプリング周波数を用いて、前記受信信号のアナログ信号をサンプリングし、前記受信信号を前記アナログ信号からデジタル信号へ変換し、
    　前記参照波周波数、前記スイッチング周波数、及び前記サンプリング周波数の少なくとも1つを制御することにより、下記の数式を満たす制御を行うことを特徴とするノイズ低減方法。
    Fref ＝ n ＊ Fsw
    (n－1)＊Fsw ≦ Fref － (1/2)Fadc
    Fref + (1/2)Fadc ≦ (n+1)＊Fsw
    n：正の整数
    Fref：参照波周波数
    Fsw：スイッチング周波数
    Fadc：サンプリング周波数     Using the switching frequency, the voltage is adjusted by turning on / off the FET of the switching power supply.
    Use the reference wave frequency to detect the received ultrasonic signal,
    Sampling the analog signal of the received signal using a sampling frequency, converting the received signal from the analog signal to a digital signal,
    A noise reduction method comprising performing control satisfying the following formula by controlling at least one of the reference wave frequency, the switching frequency, and the sampling frequency.
    Fref = n * Fsw
    (n-1) * Fsw ≤ Fref-(1/2) Fadc
    Fref + (1/2) Fadc ≤ (n + 1) * Fsw
    n: positive integer
    Fref: Reference wave frequency
    Fsw: Switching frequency
    Fadc: Sampling frequency
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