JP2006000287A - Ultrasonic transmitting and receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic transmitting and receiving apparatus which achieves the low power consumption and cost reduction of a plurality of A/D converters for performing A/D conversion of a plurality of received signals obtained by receiving ultrasonic echo. <P>SOLUTION: This ultrasonic transmitting and receiving apparatus comprises a plurality of amplifying means 23a and 23b for amplifying the received signals outputted from a plurality of ultrasonic transducers 10, the plurality of A/D converters 23c for converting the amplified received signals to digital signals, a selecting means 24 for selecting one from the amplified received signals, an A/D converter 25 for converting the selected received signal to a digital signal, and a controlling means 41 for controlling an ultrasonic probe so that an ultrasonic beam is transmitted in a desired direction and for generating a control signal for setting an amplification factor of the plurality of amplifying means 23a on the basis of the digital signal outputted from the A/D converter 25 by controlling the selecting means 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic transmission / reception device for transmitting and receiving ultrasonic waves to perform diagnosis and non-destructive inspection of internal organs.

  In general, in an ultrasonic transmission / reception apparatus used as an ultrasonic diagnostic apparatus or an industrial flaw detection apparatus, an ultrasonic probe (probe) including a plurality of ultrasonic transducers having an ultrasonic transmission / reception function is used. It is done. Using such an ultrasonic probe, the subject is scanned with an ultrasonic beam formed by combining a plurality of ultrasonic waves, and an ultrasonic echo reflected inside the subject is received. Thus, a plurality of reception signals (also referred to as “detection signals”) are output from the plurality of ultrasonic transducers, respectively. After amplifying these received signals, A / D conversion is performed to obtain detection data as digital signals. Furthermore, by performing various signal processing on the detection data, image information relating to the subject is obtained, and based on this, a two-dimensional or three-dimensional image relating to the subject is reproduced.

  As a related technique, Patent Document 1 below discloses a reception signal forming method for performing dynamic focusing on a ΔΣ modulation signal. According to this reception signal forming method, each of a plurality of signals received by a plurality of ultrasonic transducers is ΔΣ modulated, added with a predetermined delay, added, and filtered to form a reception signal. The delay time is added by applying a stretched signal to the ΔΣ-modulated signal sequence. The ΔΣ modulator has a simpler configuration and a lower cost than a general A / D converter, but since the number of channels used in the ultrasonic transmission / reception apparatus is large, it is desired to further reduce the cost.

Patent Document 2 below discloses a reception signal forming method using a bit stream signal obtained by a simple method. According to this received signal forming method, a plurality of signals received by a plurality of ultrasonic transducers are converted into bitstream signals by a quantization method other than ΔΣ modulation, added with a predetermined delay, and added. Filter to form a received signal. In Patent Document 2, the ΔΣ modulator used in Patent Document 1 is replaced with another bit stream conversion circuit to further reduce the cost. However, when A / D conversion is performed with high resolution, the cost cannot be reduced much.
Japanese Unexamined Patent Publication No. 2000-254121 (first page, FIG. 7) JP 2000-254122 A (first and fifth pages, FIG. 8)

  Therefore, in view of the above points, the present invention reduces the cost of a plurality of A / D converters for A / D converting a plurality of reception signals obtained by receiving ultrasonic echoes, and reduces power consumption. It is an object of the present invention to provide an ultrasonic transmission / reception apparatus that realizes the realization of the system.

  In order to solve the above-described problems, an ultrasonic transmission / reception apparatus according to the present invention transmits ultrasonic waves to a subject according to a plurality of drive signals, receives ultrasonic echoes reflected from the subject, and receives a plurality of reception signals. An ultrasonic probe including a plurality of ultrasonic transducers to output, drive signal generating means for generating a plurality of drive signals to be respectively supplied to the plurality of ultrasonic transducers, and output from the plurality of ultrasonic transducers A plurality of amplifying means for amplifying a plurality of received signals at an amplification factor set by the control signal, and a plurality of first signals for converting the plurality of received signals amplified by the plurality of amplifying means into a plurality of digital signals, respectively. An A / D converter; a selection means for selecting one of a plurality of received signals amplified by the plurality of amplification means; and a selection means selected by the selection means. A second A / D converter for converting the received signal into a digital signal, a driving signal generating means for controlling the ultrasonic beam to be transmitted in a desired direction from the ultrasonic probe, and a selecting means. And controlling means for generating a control signal for setting the amplification factor in the plurality of amplifying means based on the digital signal output from the second A / D converter, and a plurality of first Receiving beam forming means for performing phase matching so as to form at least one receiving focus with respect to the digital signal output from the A / D converter.

  According to the present invention, a plurality of reception signals obtained by receiving an ultrasonic echo are obtained by setting amplification factors in a plurality of amplification means based on a digital signal output from the second A / D converter. The cost of the plurality of first A / D converters for A / D conversion can be reduced, and power consumption can be reduced.

  In the present application, the transducer for one element constituting the transducer array is referred to as “ultrasonic transducer”.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a block diagram showing a configuration of an ultrasonic transmission / reception apparatus according to an embodiment of the present invention. The ultrasonic transmission / reception apparatus according to the present embodiment transmits an ultrasonic wave toward a subject, receives an ultrasonic echo reflected from the subject, and displays an ultrasonic image based on the received ultrasonic echo. It has a function.

  As shown in FIG. 1, this ultrasonic transmission / reception apparatus includes an ultrasonic probe (probe) 1 used in contact with a subject, and an ultrasonic transmission / reception apparatus connected to the ultrasonic probe 1. And a main body 2.

  The ultrasonic probe 1 has a built-in transducer array (also referred to as “array transducer”) including N ultrasonic transducers 10 arranged in a one-dimensional or two-dimensional manner. These ultrasonic transducers 10 are connected to the ultrasonic transmission / reception apparatus main body 2 via signal lines.

  The ultrasonic transducer 10 is, for example, a piezoelectric ceramic represented by PZT (Pb (lead) zirconate titanate), a polymer piezoelectric element represented by PVDF (polyvinylidene difluoride), or the like. It is constituted by a vibrator in which electrodes are formed on both ends of a piezoelectric material (piezoelectric material). In addition, in recent years, a piezoelectric material containing PZNT (an oxide containing lead, zinc, niobium, titanium), which is expected to contribute to the improvement of sensitivity and bandwidth of an ultrasonic transducer, may be used.

  When a voltage is applied to the electrodes of such a vibrator by sending a pulsed or continuous wave electrical signal, the piezoelectric material expands and contracts. By this expansion and contraction, pulsed or continuous wave ultrasonic waves are generated from the respective vibrators, and an ultrasonic beam is formed by synthesizing these ultrasonic waves. Each transducer expands and contracts by receiving propagating ultrasonic waves and generates a reception signal as an electrical signal. These received signals are used as ultrasonic detection signals.

  The ultrasonic transmission / reception apparatus main body 2 includes a plurality of switching circuits 21, a plurality of transmission system pulsar circuits 22, a plurality of reception circuits 23 constituting a reception system analog front end, a selection circuit 24, and a high resolution. A / D converter 25 is included. The ultrasonic transmission / reception apparatus main body 2 includes a plurality of shift registers 31, a plurality of phase shifters 32, and an adder 33, which constitute a digital beamformer for reception. Furthermore, the ultrasonic transmission / reception apparatus main body 2 includes a control unit 41, a display image calculation unit 42, and a display unit 50.

  The plurality of switching circuits 21 respectively connect the plurality of ultrasonic transducers 10 built in the ultrasonic probe 1 to the plurality of pulsar circuits 22 when transmitting ultrasonic waves, and when receiving ultrasonic waves, A plurality of ultrasonic transducers 10 built in the ultrasonic probe 1 are connected to a plurality of receiving circuits 23, respectively.

  The plurality of pulsar circuits 22 generate a plurality of pulsed drive signals in synchronization with the plurality of timing signals supplied from the control unit 41 and supply them to the plurality of ultrasonic transducers 10, respectively. Thereby, transmission focus processing is performed, and at least one ultrasonic beam is transmitted from the ultrasonic probe 1 in a desired direction.

  Each receiving circuit 23 includes a preamplifier 23a whose gain is controlled by a control signal, a TGC (time gain compensation) amplifier 23b, and a low-resolution A / D (analog / digital) converter 23c. Including. The reception signal output from each ultrasonic transducer 10 is amplified by the preamplifier 23a with the amplification factor set by the control signal, and the TGC amplifier 23b corrects the attenuation due to the distance that the ultrasonic wave reaches in the subject. Applied. The reception signal output from the TGC amplifier 23b is converted into a digital signal (detection data) by the A / D converter 23c.

  In the present embodiment, since the level of the received signal input to the A / D converter 23c is controlled so as to effectively use the dynamic range of the A / D converter 23c, the A / D converter 23c A low-resolution A / D converter of about 8 bits can be used. Therefore, it is possible to reduce the cost in the A / D converter 23c and realize low power consumption.

  The selection circuit 24 selects one of the plurality of reception signals amplified by the plurality of preamplifiers 23a. The A / D converter 25 has a high resolution of about 12 to 14 bits, and converts the reception signal selected by the selection circuit 24 into a digital signal. The sampling frequency of the A / D converters 23c and 25 needs to be at least about 10 times the frequency of the ultrasonic wave, and is preferably a frequency that is 16 times or more the frequency of the ultrasonic wave.

  The control unit 41 supplies a plurality of timing signals to the plurality of pulser circuits 22 so that at least one ultrasonic beam is transmitted from the ultrasonic probe in a desired direction. Here, the control unit 41 sequentially sets the transmission directions of the ultrasonic beams, and changes the transmission directions of these ultrasonic beams according to a predetermined scanning method. Moreover, the control part 41 sets the receiving direction of an ultrasonic echo sequentially at the time of reception.

  2 to 4 show the relationship between the transmission direction of the ultrasonic beam and the reception waveform of the ultrasonic echo. In each figure, (a) shows the wavefronts of the ultrasonic echoes from the reflection source existing in the transmission direction of the ultrasonic beam toward the plurality of ultrasonic transducers 11 to 18, and (b) shows those ultrasonic waves. The waveforms of a plurality of reception signals respectively output from the transducer are shown.

  FIG. 2 shows a case where an ultrasonic echo is received from the front of the center line of the plurality of ultrasonic transducers 11 to 18, and since the ultrasonic echo reaches the central ultrasonic transducers 14 and 15 earliest, The waveform of the reception signal output from the ultrasonic transducers 14 and 15 is the most advanced.

  FIG. 3 shows a case where an ultrasonic echo is received from slightly above the center line of the plurality of ultrasonic transducers 11 to 18 in the figure, and the ultrasonic echo 13 is slightly above the center. Therefore, the waveform of the reception signal output from the ultrasonic transducer 13 is the most advanced.

  FIG. 4 shows a case where an ultrasonic echo is received from obliquely below the plurality of ultrasonic transducers 11 to 18, and since the ultrasonic echo reaches the lower ultrasonic transducer 18 earliest, The waveform of the reception signal output from the ultrasonic transducer 18 is the most advanced.

  Based on such a principle, the control unit 41 controls the selection circuit 24 so as to select a reception signal corresponding to the ultrasonic transducer that reaches the earliest ultrasonic echo among the plurality of ultrasonic transducers. The reception signal output from the selection circuit 24 is converted into detection data by the A / D converter 25. Based on the detection data output from the A / D converter 25, the control unit 41 includes a plurality of preamplifiers 23a so that a substantial dynamic range is secured in the A / D converters 23c of the plurality of reception circuits 23. A control signal for setting the amplification factor is generated.

  Here, a specific method for setting the amplification factor of the preamplifier 23a will be described. FIG. 5 is a diagram illustrating a state in which an ultrasonic beam is transmitted from the ultrasonic transducer to the ultrasonic phantom. An ultrasonic phantom 60 shown in FIG. 5 is a pseudo subject used to check the performance of the ultrasonic transmission / reception apparatus. When an ultrasonic beam is transmitted from the ultrasonic transducer 10 to the ultrasonic phantom 60 and an ultrasonic echo generated by reflection of the ultrasonic beam is received by the ultrasonic transducer 10, a waveform of a reception signal as shown in FIG. can get.

  As shown in FIG. 6, the ultrasonic echo is an echo from a clear structure, a coherent echo having a good correlation with the transmission waveform when the time axis of the waveform is expanded, and a micro scatterer having a size equal to or smaller than the transmission wavelength. And an incoherent echo having no correlation with the transmission waveform. Accordingly, the coherent echo component included in the reception signal input to the A / D converter 23c is based on the reception signal corresponding to the ultrasonic transducer that reaches the earliest ultrasonic echo. The control unit 41 adjusts the amplification factor of the preamplifier 23a so that it is 0.5 to 0.8 times the full scale and the incoherent echo component is about 0.1 times the full scale of the A / D converter 23c. . When an ultrasonic beam is transmitted by forming a transmission focal point by performing transmission beam forming, the coherent echo is not attenuated in the deep part of the subject until it becomes two orders of magnitude smaller than the shallow part.

  Referring to FIG. 1 again, the shift register 31 shifts the detection data output from the A / D converter 23c in synchronization with the supplied clock signal. At this time, the amount of delay can be largely adjusted depending on whether or not a clock signal is supplied to the shift register 31. Further, the phase shifter 32 finely adjusts the delay amount for the detection data output from the shift register 31.

  Phase matching is performed so as to form at least one reception focus by giving a desired delay amount to detection data output from the plurality of A / D converters 23c by the plurality of shift registers 31 and the phase shifter 32. . The adder 33 adds the detection data values output from the plurality of phase shifters 32. Thus, reception focus processing is performed, and sound ray data in which the focus of the ultrasonic echo is narrowed is formed.

  The display image calculation unit 42 generates image data based on the sound ray data output from the adder 33. For example, the display image calculation unit 42 generates B-mode image data for displaying an ultrasonic image on a two-dimensional screen based on sound ray data obtained by sector scanning, or obtained by a Doppler method. Based on the sound ray data, Doppler image data for displaying a moving object such as a blood flow is generated, or a stable Doppler image is generated based on the sound ray data obtained by color flow mapping (CFM). CFM image data for display is generated. Here, the CFM repeats the operation of scanning the ultrasonic beam in the azimuth direction within a predetermined scanning range while repeating the transmission while fixing the ultrasonic beam until a somewhat stable Doppler frequency is obtained at each distance. This refers to the two-dimensional Doppler tomography.

  Further, the display image calculation unit 42 converts the image data in the sound ray data space into image data in the physical space by converting the scanning format of the image data. The display unit 50 includes a display device such as a CRT or LCD, for example, and displays an ultrasonic image based on the image data generated by the display image calculation unit 42.

  The control unit 41 and the display image calculation unit 42 may be configured by a central processing unit (CPU) and software, or may be configured by a digital circuit or an analog circuit. In the preamplifier 23a, the received signal may be logarithmically converted, and the gain may be changed by changing the offset voltage.

  INDUSTRIAL APPLICABILITY The present invention can be used in an ultrasonic transmission / reception apparatus used for transmitting an ultrasonic wave and observing an organ or the like in a living body.

It is a block diagram which shows the structure of the ultrasonic transmitter / receiver which concerns on one Embodiment of this invention. It is a figure which shows the relationship between the transmission direction of an ultrasonic beam and the received waveform of an ultrasonic echo in the case of receiving an ultrasonic echo from diagonally upward of an ultrasonic transducer. It is a figure which shows the relationship between the transmission direction of an ultrasonic beam and the received waveform of an ultrasonic echo in the case of receiving an ultrasonic echo from diagonally below an ultrasonic transducer. It is a figure which shows the relationship between the transmission direction of an ultrasonic beam in the case of receiving an ultrasonic echo from the front of an ultrasonic transducer, and the received waveform of an ultrasonic echo. It is a figure which shows the state which is transmitting the ultrasonic beam from the ultrasonic transducer to the ultrasonic phantom. It is a figure which shows the waveform of the received signal obtained in the state of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Ultrasonic transmitter-receiver main body 10, 11-18 Ultrasonic transducer 21 Switching circuit 22 Pulsar circuit 23 Receiving circuit 23a Preamplifier 23b TGC
23c Low resolution A / D converter 24 Selection circuit 25 High resolution A / D converter 31 Shift register 32 Phase shifter 33 Adder 41 Control unit 42 Display image calculation unit 50 Display unit 60 Ultrasonic phantom

Claims (4)

An ultrasonic probe including a plurality of ultrasonic transducers that transmit ultrasonic waves to a subject in accordance with a plurality of drive signals, receive ultrasonic echoes reflected from the subject, and output a plurality of received signals, respectively; ,
Drive signal generating means for generating a plurality of drive signals for supplying to each of the plurality of ultrasonic transducers;
A plurality of amplification means for amplifying a plurality of reception signals output from the plurality of ultrasonic transducers, respectively, with an amplification factor set by a control signal;
A plurality of first A / D converters for respectively converting a plurality of received signals amplified by the plurality of amplifying means into a plurality of digital signals;
Selecting means for selecting one of a plurality of received signals amplified by the plurality of amplifying means;
A second A / D converter for converting the received signal selected by the selecting means into a digital signal;
By controlling the drive signal generation means so that an ultrasonic beam is transmitted from the ultrasonic probe in a desired direction, and by controlling the selection means, the second A / D converter Control means for generating a control signal for setting an amplification factor in the plurality of amplification means based on the output digital signal;
Receiving beam forming means for performing phase matching so as to form at least one receiving focus with respect to digital signals output from the plurality of first A / D converters;
An ultrasonic transmission / reception apparatus comprising: Each of the plurality of amplification means is
A first amplifier that amplifies a reception signal output from each ultrasonic transducer at an amplification factor set by a control signal and supplies the amplified signal to the selection unit;
A second amplifier for correcting the attenuation of the received signal output from the first amplifier according to the distance reached by the ultrasonic wave in the subject and supplying the corrected signal to each first A / D converter; ,
The ultrasonic transmission / reception apparatus according to claim 1, comprising:   The ultrasonic transmission / reception apparatus according to claim 1, wherein a resolution of the plurality of first A / D converters is lower than a resolution of the second A / D converter.   4. The control unit according to claim 1, wherein the control unit controls the selection unit to select a reception signal corresponding to an ultrasonic transducer that reaches an earliest ultrasonic echo among the plurality of ultrasonic transducers. The ultrasonic transmitting / receiving apparatus according to claim 1.

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