JPH02209135A - Ultrasonic transmitter/receiver - Google Patents

Abstract

PURPOSE:To suppress a grating side lobe by comparing the amplitude values of output signals obtained from first and second receiving means and selecting the signal of the smaller amplitude value or of the equal value as the output signal. CONSTITUTION:A transmission part 20 excites respective vibrators 1-1-1-32 forming an opening in a probe 10 and the respective vibrators 1-1-1-32 transmit electric signals as ultrasonic output signals. A reflected signal from a reflector is received again by the probe 10 and the respective vibrators 1-1-1-32 convert the signal to the electric signal and output the signal. The received signal is amplified by a #1 preamplifier 2-1 in a #1 reception part 30 and a #2 preamplifier 2-2 in a #2 reception part 40, and #1 and #2 focus control circuits 3-1 and 3-2 add and synthesize the taken-out signal through a correspondent delay element having a delay time and output the signal as one output signal. #1 and #2 log amplifiers 4-1 and 4-2 logarithmically amplify the input signal and an analog signal is quantized by #1 and #2 AD converters 5-1 and 5-2 in a signal processing part 50. Then, a signal select circuit 6 compares the two input signals and select the equal value. When there is the relation of the size, the smaller value is selected and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an ultrasonic transmitting/receiving device used in, for example, an ultrasonic diagnostic device, and particularly an ultrasonic transmitting/receiving device with improved beam directivity characteristics so as to suppress dalating sidelobes. It is related to the device.

[Prior Art] Fig. 1O is a block diagram of a conventional ultrasonic transmitting/receiving device. In the figure, 1-1-1-32 is a transducer from #1 to #32 forming an aperture for transmitting and receiving ultrasonic waves. 10 is, for example, a probe in which transducers 1-1 to 1-32 are arranged linearly at regular intervals (generally referred to as a linear array probe);
is a preamplifier, 3 is a focus circuit, and 4 is a log amplifier (
(logarithmic amplifier), 31 is preamplifier 2, focus circuit 3
5 is an analog-to-digital converter (hereinafter referred to as AD converter); 20 is a transmitting unit that generally also includes a transmission focus circuit; and 80 is a digital scan φ converter (hereinafter referred to as DSC). , 70 is a display.

The operation of FIG. 1O will be explained. The transmitter 20 excites each of the transducers 1-1 to 1-32 in the probe 10 with a burst wave having a frequency of approximately 1 to 10 MHz at regular intervals via delay elements each having a corresponding delay time. . The method of exciting the vibrator through this delay element is called the electronic focusing method, and its details will be explained with reference to FIG. Each of the transducers 1-1 to 1-32 to which an electric signal is applied by this electronic focusing method converts the electric signal into an acoustic signal, and transmits it from the rectangular aperture of the probe 10 as an ultrasonic output signal. do. Here, since each of the transducers 1-1 to 1-32 has a linear array structure, the ultrasonic acoustic signal obtained by combining the output waves from each transducer has a certain directional characteristic with respect to the rectangular aperture surface. The ultrasonic acoustic signal transmitted from the probe IO propagates through a medium (for example, inside the human body), and the reflected signal from the reflecting object, which is the point of change in acoustic impedance, is received by the probe 10 again, and each The transducers 1-1 to 1-32 each convert the received ultrasonic acoustic signals into electrical signals and output them. The received signals for these 32 channels are each amplified by the preamplifier 2 in the receiving section 31 for each channel, and then supplied to the focus circuit 3.

FIG. 3 is a diagram illustrating the delay time of a delay element included in the focus circuit. That is, the conventional focus circuit provides the minimum delay time for the signals obtained from the transducers 1-1 and 1-32 at both ends of the linear array arrangement, and the minimum delay time for the signals obtained from the transducers 1-18 and 1-17 at the center of the array arrangement. The maximum delay time is given to the obtained signal, and the intermediate delay time corresponding to the arrangement position of each transducer is given to the signal obtained from the transducers located between both ends and the center of the array arrangement. Adjustments are made so that the arrival times of reflected signals from a reflecting object at a desired focus distance are made equal.

Therefore, the characteristic of this delay time is set corresponding to the focus distance. The focus circuit 3 adds and synthesizes the output signals taken out by adding the delay time described above to each of the input 32 channels of signals, and supplies the signal to the log amplifier 4. The log amplifier 4 amplifies the input signal using logarithmic characteristics and supplies the output signal to the AD converter 5. A
The D converter 5 quantizes the input analog signal and supplies a digital signal to the DSC 60. The DSC 60 temporarily stores the input signal in a built-in frame memory, and displays this as an ultrasound video signal on the display 70.

FIG. 11 is a diagram showing beam directivity characteristics of a conventional ultrasonic transmitter/receiver. The figure shows a perpendicular line in the center of the rectangular aperture surface of the linear array probe, and the beam directivity characteristic of a plane passing through the perpendicular line and along the array arrangement direction of the aperture surface (hereinafter referred to as the horizontal plane), and the horizontal axis is the perpendicular line. This is an angle where the direction of is 0 degrees, the left side of the perpendicular to the horizontal plane is negative, and the right side is positive. The vertical axis represents the received signal amplitude value at each angle, which is normalized using the maximum signal amplitude value of the ultrasonic received signal in the horizontal plane as OdB. Figure 11 shows the transmission frequency 5) Il
fz s This is the horizontal plane directivity characteristic when the number of vibration elements is 32 and the interval between vibration elements is the length of one wavelength of the transmission frequency λ, and as shown in the figure, in addition to the main lobe at the center position of 0 degrees, It can be seen that unnecessary grating side lobes are generated nearby.

Generally, the angle at which this grating sidelobe occurs is determined by the transmission frequency of the vibrator and the interval (pitch) between the vibrating elements, and is a cause of false images.

[Problems to be Solved by the Invention] In the conventional ultrasonic transmitting/receiving device as described above, in addition to the main lobe, undesirable grating side lobes are generated in the ultrasonic transmitting/receiving beam directivity characteristics, so that false images may occur. There is a problem that when applied to an ultrasound diagnostic device, it may cause misdiagnosis.

SUMMARY OF THE INVENTION In order to solve these problems, it is an object of the present invention to provide an ultrasonic transmitter/receiver with improved directivity characteristics that suppress grating side lobes.

[Means for Solving the Problems] The ultrasonic transmitting and receiving device according to the first invention includes a probe formed by arranging a plurality of transducers in an array, and an aperture set in the probe. Excite all included oscillators,
a transmitting means for transmitting an ultrasonic signal, and when the transducers included in the aperture receive the ultrasonic signal, half of the total number of transducers included in the aperture from one end of the array of transducers forming the aperture; a first receiving means that performs electronic focusing processing to obtain an output signal after amplifying received signals obtained from each of the transducers, and forming an aperture when the transducer included in the aperture receives an ultrasonic signal; a second receiving means for obtaining an output signal by amplifying received signals obtained from half of the total number of transducers included in the aperture from the other end of the array of transducers, and performing electronic focusing processing; 1st
and comparison and selection means for comparing the amplitude values of the output signals obtained from the receiving means and the second receiving means and selecting the signal with the smaller amplitude value or the signal of the same value as the output signal. .

The ultrasonic transmitter/receiver according to the second invention includes a probe formed by arranging a plurality of transducers in an array, and excites all the transducers included in an aperture set in the probe. ,
a transmitting means for transmitting an ultrasonic signal, and when the transducers included in the aperture receive the ultrasonic signal, half of the total number of transducers included in the aperture from one end of the array of transducers forming the aperture; a first receiving means that obtains an output signal by performing electronic focusing processing after respectively amplifying received signals obtained from a number of transducers exceeding the number of transducers; After amplifying the received signals obtained from more than half of the total number of transducers included in the aperture from the other end of the array of transducers forming the aperture, electronic focus processing is performed to obtain output signals. Comparing the amplitude values of the output signals obtained from the receiving means, the first receiving means and the second receiving means, and selecting the signal with the smaller amplitude value or the signal with the same value as the output signal. It is equipped with means.

[Function] In the first and second inventions, the probe is formed by arranging a plurality of vibrators in an array, and the transmitting means transmits all the vibrations contained in the opening formed in the probe. Excite the child and transmit ultrasound signals.

In this first invention, a transducer included in the aperture receives the ultrasonic signal transmitted and reflected from a reflecting object, and the first receiving means is arranged in an array of transducers forming the aperture. After amplifying the received signals obtained from half of the total number of transducers included in the aperture from one end,
The second receiving means performs electronic focusing processing to generate an output signal in which grating sidelobes in one direction are suppressed, and the second receiving means receives all the transducers included in the aperture from the other end of the array of transducers forming the aperture. After amplifying the received signals obtained from half the number of transducers, electronic focusing processing is performed to generate an output signal in which grating side lobes in the other direction are suppressed, and the comparing and selecting means compares and selects the first receiving means and the first receiving means. The amplitude values of the output signals obtained from the two receiving means are compared, and the signal with the smaller amplitude value or the signal with the same value is selected as the output signal to obtain a received signal in which grating sidelobes in both directions are suppressed.

Further, in this second invention, a transducer included in the aperture receives the ultrasonic signal transmitted and reflected from a reflecting object, and the first receiving means is arranged in an array of transducers forming the aperture. After amplifying the received signals obtained from more than half of the total number of transducers included in the aperture from one end, electronic focusing processing is performed to generate a unidirectional grating without widening the main lobe beam width too much. The second receiving means generates an output signal with suppressed side lobes, and receives signals from the other end of the array of transducers forming the aperture, the number of which is more than half of the total number of transducers included in the aperture. After amplifying each received signal, the first receiving means performs electronic focusing processing to generate an output signal in which the grating side lobe in the other direction is suppressed without widening the beam width of the main lobe too much. The amplitude values of the output signals obtained from the first and second receiving means are compared, and the signal with the smaller amplitude value or the signal with the same value is selected as the output signal, and the beam width of the main lobe is not widened too much and the amplitude values of the output signals in both directions are compared. A received signal with grating sidelobes suppressed is obtained.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the ultrasonic transmitter/receiver of the present invention.
0 and 70 are the same as the conventional device shown in FIG.

2-11 and 2-2 are #1 and #2 preamplifiers, a- and 3-2 are #1 and #2 focus circuits, 4-1 and 4-2 are #1 and #20 amplifiers, 30 and 40 are #1
Receiving unit and #2 receiving unit, 5-1 and 5-2 are #1 and #2
2 is an AD converter, and 6 is a signal selection/circuit.

The operation shown in FIG. 1 will be explained. Similar to the conventional device, the transmitter 20 transmits each vibrator 1 that forms an aperture in the probe 10 with a burst wave having a frequency of about 1 to 10 MHz at regular intervals.
-1 to 1-32 are excited by the electronic focusing method. Each transducer 1-1-1-32 to which an electric signal is applied converts the electric signal into an acoustic signal, and transmits it from the rectangular aperture of the probe 10 as an ultrasonic output signal. Probe I
The wave is transmitted from O, propagates through the medium, and the reflected signal from the reflecting object, which is the point of change in acoustic impedance, returns to the probe l.
Each of the transducers 1-1 to 1-32 converts the received ultrasonic acoustic signal into an electrical signal and outputs the electrical signal.

Each of these vibrators! A major feature of the present invention is a processing method in which output signals from -1-1-32 are individually received and processed by a pair of receiving sections 30 and 40, and then selectively combined.

FIG. 2 is a diagram illustrating a probe aperture and a pair of receiving apertures of the present invention. (A) in the same figure shows that the probe opening has a rectangular opening surface, and the length in the longitudinal direction of this opening surface is equal. In (a) of the same figure, the probe aperture length is 2
This is a case where the #1 receiving port and the #2 receiving port are provided so as to be equally divided.

That is, if #1 and #2 receiving port length is 91, then 11-1/
They are in a 2L relationship. The case (a) in FIG. 2 will be explained below. The received signals for 16 channels from the transducers 1-1 to 1-16 are sent to the #1 preamplifier 2-1 in the #1 receiving section 30.
Also, the 16 channels of received signals from the transducers 1-17 to 1-32 are sent to the #2 preamplifier 2- in the #2 receiving section 40.
2, each channel is amplified separately.

#1 The output signal of 16 channels from preamplifier 2-1 is #
The output signals of 16 channels from the #2 preamplifier 2-2 are supplied to the #1 focus circuit 3-1 and the #2 focus circuit 3-2, respectively. The #1 and #2 focus circuits may be a conventional focus circuit divided into two parts. That is, the third
The horizontal axis of the figure is 2 by the center line between transducer numbers 16 and 17.
The left side is the delay characteristic for #1 focus circuit,
Delay elements corresponding to the respective channel signals are provided so that the delay characteristics for the #2 focus circuit are on the right side.

#1 and #2 focus circuits 3-1 and 3-2 add and synthesize signals taken out through delay elements having delay times corresponding to the input 16-channel signals, respectively, and output them as one output signal. #1 and #20 are supplied to Guanbu 4-1 and 4-2.

#1 and #20 amplifiers 4-1 and 4-2 logarithmically amplify the input signals and supply them to #1 and #2 AD converters 5-1 and 5-2, respectively.

FIG. 4 is a diagram showing the beam directivity characteristic of the output signal from the #1 receiving section 30, and FIG. 5 is a diagram showing the beam directivity characteristic of the output signal from the #2 receiving section 40.

4 and 5 will be explained. The plane of the directional characteristics (the above-mentioned horizontal plane), the angle on the horizontal axis, the normalized signal amplitude on the vertical axis, the transmission frequency, and the vibration element spacing in Figures 4 and 5 are exactly the same as those explained in Figure 11. It is something. Here, FIG. 4 shows beam directivity characteristics obtained by receiving signals from the transducers 1-1 to 1-16 and being processed by the #1 receiving section 30.
Grating side lobes occur only around 140 degrees on the left side, and almost none exist on the right side. In addition, Fig. 5 shows the received signals from transducers 1-17 to 1-32 to #2.
This is the beam directivity characteristic received and processed by the receiving unit 40, and shows that grating side lobes occur only around +40 degrees on the right side, and are almost absent on the left side. Therefore, from Fig. 4, we take the directional characteristics to the right of the center (positive angular range) where there is no grating sidelobe, and from Fig. 5, we take the directional characteristics to the left of the center (negative angular range), It can be seen that by combining the two, a directivity characteristic in which grating sidelobes in both directions are almost eliminated can be obtained.

The analog signals output from the #1 and #2 receiving sections 30 and 40, respectively, are sent to the #1 and #2 AD in the signal processing section 50.
The signals are quantized by converters 5-1 and 5-2 and supplied to the signal selection circuit 6 as digital signals.

The signal selection circuit 6 includes, for example, a digital comparator and a selector, compares two input signals, selects the equal value when the digital values of the two input signals are equal, and selects the equal value when the digital values of the two input signals are equal. If there is a size relationship between the values, the smaller value is selected and output. In this way, the signal selection circuit 6 connects the #1 and #2 AD converters 5-1 and 5-2.
Select and output one of the input signals from the input signals. The signal selection circuit 6 selectively combines the two beam directivity characteristics, and FIG. 6 shows the directivity characteristics as a result of the combination.

FIG. 6 is a diagram showing improved beam directivity characteristics of the grating side lobe of the present invention.

The directional characteristics, horizontal axis, vertical axis, transmission frequency, vibration element spacing, etc. in FIG. 6 are exactly the same as those explained in FIGS. 4, 5, and 11.

In the figure, the grating sidelobes have been almost eliminated, and there is almost no risk of false images occurring. However, the width of the main lobe has increased, resulting in a slightly broader beam.

FIG. 7 is a diagram showing beam directivity characteristics obtained by enlarging the main lobe of FIG. 6 in the angular direction. This figure is a main lobe directional characteristic diagram that is completely the same as that explained in FIG. 6, except that the angle scale on the horizontal axis is enlarged. In addition, the solid line in the figure shows the directivity of the main lobe due to the output of the #1 receiver 30 (that is, only one receiver), and the broken line indicates the directivity of the main lobe due to the output selectively combined by the signal selection circuit 6. ing. It can be seen from the figure that the width of the main lobe after selective synthesis becomes slightly wider.

As a method of narrowing the width of the main lobe after this selective synthesis, there is a method of widening the interval between the vibrating elements and increasing the aperture area. For example, FIG. 8 shows a beam directivity characteristic diagram when the interval between the vibrating elements is twice that of FIGS. 4 and 5, that is, the length of two wavelengths of the transmission frequency is 2λ.

FIG. 8 is a diagram showing beam directivity characteristics with an improved main lobe width according to the present invention, and is the same as that explained in FIG. 4 except that the spacing between the vibrating elements is doubled. In the figure, the solid line indicates the beam directivity characteristic due to the output of the #1 receiver 30, and the broken line indicates the beam directivity characteristic due to the output selectively combined by the signal selection circuit 6.

FIG. 9 is a diagram showing a beam directivity characteristic obtained by enlarging the main lobe of FIG. 8 in the angular direction. This figure is the same main lobe directivity diagram as explained in FIG. 8, except that the angle scale on the horizontal axis is enlarged. In addition, the solid line in the figure shows the directivity of the main lobe due to the output of the #1 receiver 30 (that is, only one receiver), and the broken line indicates the directivity of the main lobe due to the output selectively combined by the signal selection circuit 6. ing. Comparing FIG. 9 with FIG. 7, it can be seen that the width of the main lobe is narrower. By narrowing the width of the main lobe, the resolution of the ultrasound image signal obtained by receiving and processing the reflected signal obtained from the probe 10 is improved, and high-quality image display becomes possible.

The signal selection circuit 6 supplies the selectively combined signals to the DSC 80. The DSC 80 temporarily stores the input signal in its built-in frame memory, and displays this as an ultrasound video signal on the display 70.
Displayed by

In the above embodiment, an example was shown in which the signal selection circuit 6 compares the magnitude relationship between the two digital signals and performs the selection operation. Exactly the same effect can be expected even if the magnitude relationship of the analog signals is compared by an analog voltage comparator and the selection operation is performed based on the comparison result.

In addition, in the above embodiment, as shown in FIG. 2 (A), #1
Although the example is shown in which the length I11 of the receiving and receiving port #2 is equal to 1/2 of the probe aperture length, the present invention is not limited thereto. #
If the length 12 of the receiving and receiving ports 1 and #2 exceeds the probe aperture length 172, that is, 1/2>112L. In this case, the output signal from the vibrator in the overlapping portion of the two receiving apertures is received and processed by both the #1 and #2 receiving sections 30 and 40. In this case, the effect of suppressing the grating side lobe is somewhat reduced, but the width of the main lobe can be narrowed without increasing the interval between the vibrating elements. In this way, it is possible to realize a product that successfully balances the two trade-off characteristics. For example, as shown in FIG. 2 (1), when the #1 and #2 receiving port lengths 13 are 172 or less than the probe aperture length, that is, 112L (l/3) may be used.

Further, in the above embodiment, an example of a linear array probe in which a plurality of vibrating elements are arranged in a straight line at regular intervals was shown, but the present invention is not limited to this, and the present invention is not limited to this. It is also possible to apply the present invention to a convex-type probe for diagnosing the abdomen of a human body, for example.

[Effects of the Invention] As described above, according to the present invention, the transducers of an ultrasonic probe arranged in an array can be divided into two groups that do not overlap at all or two groups that partially overlap at the center of the array. By individually receiving and processing the received signals obtained from the transducers belonging to each group, comparing the amplitudes of the individually received and processed output signals, and selecting the output signal with the smaller amplitude value, Since it is possible to obtain a beam directivity characteristic in which the grating side lobe is sufficiently suppressed, or a beam directivity characteristic in which the grating side lobe suppression effect is slightly reduced but the beam width of the main lobe is narrowed,
The effect of preventing false images in ultrasound received images has been achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an ultrasonic transmitter/receiver according to the present invention, FIG. 2 is a diagram illustrating a probe aperture and a pair of receiving apertures according to the present invention, and FIG. 3 is a diagram showing a focus circuit. A diagram explaining the delay time of the built-in delay element, Figure m4 is a diagram showing the beam directivity characteristic of the output signal from the #1 receiving section 30, and FIG. 5 is a diagram showing the beam directivity characteristic of the output signal from the #2 receiving section 40. 6 is a diagram showing improved beam directivity characteristics of the grating side lobe of the present invention. FIG. 7 is a diagram showing beam directivity characteristics obtained by enlarging the main lobe of FIG. 6 in the angular direction. The figure shows the beam directivity characteristic with improved main lobe width of the present invention, Figure 9 shows the beam directivity characteristic with the main lobe of Figure 8 expanded in the angular direction, and Figure 10 shows the beam directivity characteristic of the conventional ultrasonic wave. FIG. 11, which is a block diagram of a transmitting/receiving device, is a diagram showing beam directivity characteristics of a conventional ultrasonic transmitting/receiving device. In the figure, ■-1 to 1-32 are vibrators, 2 is a preamplifier, 2-1 is a #1 preamplifier, 2-2 is a #2 preamplifier, 3 is a focus circuit, 3-1 is a #1 focus circuit,
3-2 is #2 focus circuit, 4 is log amplifier, 4-1
is #10 Guamp, 4-2 is #20 Guamp, 5 is AD
Converter, 5-1 is #IAD converter, 5-2 is #2 AD converter, 10 Lt probe, 20 Get transmitter, 30 is #1 receiver, 31 is receiver, 4o is #2 receiver , 50 is a signal processing section, 60 is a DSC, and 70 is a display device.

Claims (2)

[Claims] (1) A probe formed by arranging a plurality of transducers in an array, and a transmitting means that excites all the transducers included in an aperture set in the probe and transmits an ultrasonic signal. , When the transducers included in the aperture receive an ultrasonic signal, receive signals obtained from half of the total number of transducers included in the aperture from one end of the array of transducers forming the aperture. a first receiving means that performs electronic focus processing to obtain an output signal after amplification, and the other end of the array of transducers forming the aperture when the transducers included in the aperture receive an ultrasonic signal; a second receiving means for obtaining an output signal by performing electronic focusing processing after amplifying received signals obtained from half of the total number of transducers included in the aperture; An ultrasonic transmitting/receiving device comprising: comparison and selection means for comparing amplitude values of output signals obtained from the receiving means and selecting a signal with a smaller amplitude value or a signal with an equal value as an output signal. (2) A probe formed by arranging a plurality of transducers in an array, and a transmitting means that excites all the transducers included in an aperture set in the probe and transmits an ultrasonic signal. , When the transducers included in the aperture receive an ultrasonic signal, the ultrasonic signal is obtained from more than half of the total number of transducers included in the aperture from one end of the array of transducers forming the aperture. a first receiving means that performs electronic focusing processing to obtain an output signal after amplifying each received signal; and an array of transducers that form an aperture when the transducers included in the aperture receive an ultrasonic signal. a second receiving means that obtains an output signal by performing electronic focusing processing after respectively amplifying received signals obtained from more than half of the total number of transducers included in the aperture from the other end; Comparing and selecting means for comparing the amplitude values of the output signals obtained from the receiving means and the second receiving means and selecting the signal with the smaller amplitude value or the signal of the same value as the output signal. Ultrasonic transceiver device.