JP2009153773A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately perform delay addition in a high frequency echo with the use of a low sampling frequency in a beam former. <P>SOLUTION: Two kinds of clocks in positive phase and reverse phase to be supplied from a control part 9 are prepared in order to provide excellent image quality by A/D conversion at a speed equal to that in a conventional manner even when a high frequency signal is used. The clocks are selected so as to allow adjacent vibrators to be in the different phases in A/D converters 51-58. Thus, the delay addition is accurately performed without raising the sampling frequency. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that transmits and receives using an array transducer.

  The principle of an ultrasonic diagnostic apparatus for displaying the shape of a body tissue and the blood flow state is already widely known. The general operation of the ultrasonic diagnostic apparatus will be described with reference to FIG.

  The transmission pulse generated by the transmission unit 1 drives a plurality of transducers (not shown) in the probe 3 via the aperture switch 2, and the generated ultrasonic pulse is irradiated to the subject (not shown). The

  Signals reflected inside the subject (not shown) are returned to electrical signals by a plurality of transducers (not shown) in the probe 3 and input to the receiving unit 5 via the aperture switch 2 and the limiter 4.

  In the receiving unit 5, the echo signal is converted to digital by an A / D converter (not shown), and delayed and added by a digital delayer and an adder (not shown).

  The signal subjected to delay addition is subjected to signal processing in accordance with the application by the signal processing unit 6. For example, amplitude information is extracted in the B mode, and phase detection is performed on the echo signal in the Doppler mode, and a plurality of signals are compared to obtain velocity information from the amount of phase rotation.

  The data processed in this way is converted into a form suitable for display such as scan conversion in the image construction unit 7 and displayed on the display unit 8.

  Control of the entire system is performed by the control unit 9.

  Next, the beamformer unit will be described with reference to FIG.

  Inside the probe 1, there are vibrators 11 to 26, which are driven by pulses sent by a transmitter (not shown). The high voltage switch 27 is for selecting a vibrator to be driven. In the state shown in the figure, the vibrators 11 to 18 are selected. By sequentially switching the high voltage switch 27, the position of the opening can be moved.

  In reception, a reception signal obtained by the vibrator (the vibrators 10 to 17 in the state of this figure) is input to the receiving unit 5 via the limiters 31 to 38. The limiters 31 to 38 limit the amplitude of the pulse so that the receiving circuit is not destroyed by the high-voltage transmission pulse.

  The signal input to the receiving unit 5 is amplified to an appropriate amplitude by the gain variable amplifiers 41 to 48 and converted into a digital signal by the A / D converters 51 to 58. Conversion timing is determined by the A / D conversion clock generator 28 of the controller 9.

  The digitized signal is delayed by a predetermined delay by digital delay units 61 to 68 and added by an adder 69 (see, for example, Patent Document 1).

  Another example of the configuration of the ultrasonic diagnostic apparatus will be described with reference to FIG.

  This figure is different from FIG. 5 in that there is a sorting unit 10 between the limiter 4 and the receiving unit 6.

  In a method called linear scanning, since the transmitted and received beams are not deflected, the amount of delay given to the digital delay device is symmetric about the aperture center. By using this and adding a signal at the same position from the center of the aperture in advance and then performing a delay, it becomes possible to reduce the amount of circuit components. This method is generally called foldover.

  A diagram of a beamformer corresponding to foldover is shown in FIG.

  The sorting unit 10 includes voltage-current converters 71 to 78, a cross point switch (CPS) 79, and current-voltage converters 81 to 84.

Signals are added by being converted into current signals when passing through the CPS 79.
JP-A-10-328181

  In a conventional beam former of an ultrasonic diagnostic apparatus, the A / D conversion speed needs to be sufficiently high with respect to an input signal.

  However, when looking at a fine structure such as the body surface, it is necessary to increase the transmission / echo frequency, and the speed of A / D conversion must be increased, which increases the cost.

  An object of the present invention is to provide a good image quality by A / D conversion at a speed equivalent to that of the prior art even when a high-frequency signal is used.

The present invention solves the problem by dividing A / D converters into a plurality of groups.
An ultrasonic diagnostic apparatus of the present invention includes a probe including a plurality of transducers that transmit and receive ultrasonic waves in a subject, a plurality of transmission units that drive the plurality of transducers, and drive outputs of the plurality of transmission units. A plurality of high-voltage switches that determine which transducer to connect to,
A beam former that performs A / D conversion on the echo signals obtained from the plurality of transducers by a plurality of A / D converters, adds a digital delay, and
A plurality of phases are used for the phase of the conversion clock of the A / D converter applied to the plurality of A / D converters of the beamformer.

  As a result, the problem is solved by dividing the A / D converters into a plurality of groups and changing the conversion timing for each group.

  According to the second aspect of the present invention, the signals of adjacent vibrators are adapted to high frequency input by changing the A / D conversion timing.

  In the invention of claim 3, a cross-point switch is provided between the high-voltage switch and the A / D converter to enable opening folding, thereby reducing the circuit quantity and cost.

  In the invention of claim 4, in the invention of claim 3, the circuit of the circuit is maintained while maintaining the image quality by making the connection of the cross point switch 1 to 2 at the center of the opening and 1 to 1 at the end of the opening. The amount is reduced.

  According to a fifth aspect of the invention, in the third aspect of the invention, the cross-point switch connection is provided at the end of the opening by providing a vibrator that is not connected, thereby reducing the circuit quantity while maintaining the image quality. is there.

  In the invention of claim 6, in the invention of claim 3, a high frequency signal is accurately measured by converting the two vibrators at the center of the opening by two A / D converters having different conversion timings. Is.

  In the invention of claim 7, in the invention of claim 3, the voltage-current converter is installed before the crosspoint switch, and the current-voltage converter is installed after the crosspoint switch. Since the number is reflected in the input voltage of the A / D converter, the amount of signal processing is reduced.

  According to the ultrasonic diagnostic apparatus of the present invention, even when a high-frequency signal is used, the clock supplied from the control unit in order to provide a good image quality by A / D conversion at the same speed as the conventional one is in the normal phase and the reverse phase. By preparing two types and selecting clocks so that adjacent transducers have different phases in the A / D converter, delay addition can be performed with high accuracy without increasing the sampling frequency.

  Hereinafter, implementation of this invention is demonstrated using FIGS. 1-3.

(Embodiment 1)
FIG. 1 is a block diagram of a beam former of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. Compared with FIG. 5, FIG. 1A has two systems of A / D conversion clocks in the control unit 9, and two clocks of normal phase and reverse phase are supplied. The difference is that each of the / D converters 51 to 58 selects one of the two clocks.

  FIG. 1A shows the selection of a clock in an 8-channel opening.

  Clocks are arranged in the order of normal phase and reverse phase with the opening center as a boundary.

  When receiving an ultrasonic signal, the difference in delay between adjacent channels is small, so converting one of the adjacent signals in the normal phase and the other in the reverse phase doubles the apparent sampling rate. It is possible to

  This makes it possible to deal with high-frequency echo signals without increasing the speed of the A / D converter.

(Embodiment 2)
FIG. 2 is a block diagram of a beam former of the ultrasonic diagnostic apparatus according to the second embodiment of the present invention.

  FIG. 2A shows a case where the two-phase clock according to the first embodiment is applied to the second conventional example. In this embodiment, since the order of signals can be sorted by a CPS (cross point switch) 79, it is not necessary to switch the clock of the A / D converter.

  FIG. 2B shows the selection of the clock in the 8-channel opening. Further, the A / D converter can be divided into a plurality of groups, and the conversion timing can be changed for each group.

(Embodiment 3)
FIGS. 3A to 3C show examples of connection of CPS units in the beam former of the ultrasonic diagnostic apparatus according to the third embodiment of the present invention.

  FIGS. 3A to 3C assume a 32-channel opening, and show half of them. The top is the edge of the opening and the bottom is the opening center. The transducers expressed in black are converted by two A / D converters (with different conversion clock phases), and the shaded transducers are digitally converted by one A / D converter, white Is a vibrator that is not used. In the A / D converter, black represents the normal phase and white represents the reverse phase.

  In the vicinity of the center of the opening, the difference in delay time between adjacent transducers is small, so that the apparent sampling frequency is increased using a plurality of A / D converters. At the end of the opening, the difference in delay time between adjacent vibrators is large, so it can be considered that signals are coming in with different phases, and a plurality of A / D converters can be connected to one vibrator. No need to use it.

  Further, at the end, as shown in FIG. 3B, a vibrator that is not used at the end is provided, and the apparent opening can be widened by thinning.

  Furthermore, in the central portion, as shown in FIG. 3C, two transducers can be bundled and digitized by two A / D converters having different clock phases.

  In these figures, the arrangement of end portions is bundled with two patterns that are spaced apart from each other, and two transducers that connect one transducer to two A / D converters at the center. Although the patterns connected to the two A / D converters are shown, these patterns may be mixed.

  As a similar method, for example, a method like Patent Document 1 is known. However, in the method of Patent Document 1, since a plurality of A / D converters are used for all transducers, A / D conversion is performed. There is a problem that the required amount of the vessel increases and the cost does not decrease. On the other hand, according to the method of the present invention, by assigning a plurality of A / D converters only to the center of the aperture having the same phase, the beamformer can be adapted to a high frequency while avoiding the cost problem. Is possible.

  Furthermore, in this method, since the signal in the crosspoint switch is converted to a current, when two A / Ds are connected to the output as shown in FIG. 3D, the output current is halved. Thus, the amplitude when converted to voltage is halved. If the signal obtained from one transducer is digitally converted by two A / D converters and used for delay addition, the amplitude must be halved. In this circuit, the amplitude is not increased. Can be halved.

  As is clear from the above-described embodiment, the present invention is capable of delay-adding high-frequency echo signals with high accuracy without using a high-speed A / D converter in the beamformer, and has high performance at low cost. Can be realized.

Explanatory drawing of the parallel reception method of the ultrasonic Doppler blood flow meter in the 1st Embodiment of this invention Explanatory drawing of the parallel reception method of the ultrasonic Doppler blood flow meter in the 2nd Embodiment of this invention Explanatory drawing of the parallel reception method of the ultrasonic Doppler blood flow meter in the prior art example of this invention The block diagram of the ultrasonic diagnosing device in the prior art example of this invention The block diagram of the beam former part of the ultrasonic diagnosing device in the prior art example of this invention Block diagram of an ultrasonic diagnostic apparatus in another conventional example of the present invention The block diagram of the beam former part of the ultrasonic diagnosing device in another prior art example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission part 2 Aperture switch 3 Probe 4 Limiter 5 Reception part 6 Signal processing part 7 Image processing part 8 Display part 9 Control part 10 Sort part 11-26 Vibrator 27 High voltage switch 28 A / D conversion clock generation part 29 Phase inverter 31-38 Limiter 41-48 Variable gain amplifier 51-58, 151-166 A / D converter 61-68 Digital delay device 69 Adder 71-78 V-I converter 79 Crosspoint switch (CPS)
81-84 I-V converter

Claims (7)

A probe composed of a plurality of transducers for transmitting and receiving ultrasonic waves in a subject, a plurality of transmission units for driving the plurality of transducers, and a transducer to which the drive outputs of the plurality of transmission units are connected A plurality of high pressure switches to determine,
A beam former that performs A / D conversion on the echo signals obtained from the plurality of transducers by a plurality of A / D converters, adds a digital delay, and
An ultrasonic diagnostic apparatus using a plurality of phases as the phase of a conversion clock of an A / D converter applied to a plurality of A / D converters of the beam former. The ultrasonic diagnostic apparatus according to claim 1, wherein the phase of the clock applied to the plurality of A / D converters is set to two phases of a normal phase and a reverse phase, and is switched for each transducer from the center of the opening. The ultrasonic diagnostic apparatus according to claim 1, wherein a crosspoint switch is provided between the high-voltage switch and the A / D converter. 4. The ultrasonic diagnostic apparatus according to claim 3, wherein the connection of the cross point switch to the A / D converter is one to two at the center of the opening and one to one at the end of the opening. The ultrasonic diagnostic apparatus according to claim 3, wherein a vibrator that is not connected to the A / D converter is provided at an end of the opening. 4. The ultrasonic diagnostic apparatus according to claim 3, wherein an electrical signal of two adjacent transducers is added to the central portion of the opening, and A / D conversion is performed by two A / D converters having different conversion timings. A voltage-current converter is provided before the crosspoint switch, and a current-voltage converter is provided after the crosspoint switch. The current is distributed according to the number of connected A / D converters and reflected in the input voltage of the A / D converter. The ultrasonic diagnostic apparatus according to claim 3.

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