JP3850953B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus including a digital beam former.
[0002]
[Prior art and problems]
In a conventional ultrasonic diagnostic apparatus, received signals from ultrasonic transducer elements (hereinafter referred to as elements) are added by a phasing addition circuit, and the received signal after the addition is converted into a digital signal by an A / D converter. Is done. That is, the phasing addition is performed in an analog manner. Incidentally, the phasing addition is performed in order to electronically form an ultrasonic beam pattern by adjusting the phase of each received signal and to perform electronic focusing.
[0003]
In recent years, digital beam formers have been put into practical use against the background of lower prices of A / D converters. In this method, received signals from each element are individually A / D converted and subjected to phasing addition by digital processing. This generally has the advantage of less noise compared to analog processing.
[0004]
By the way, recently, a high-frequency probe that transmits and receives an ultrasonic wave having a frequency higher than a normal frequency has been provided. According to the sampling principle, the higher the frequency, the higher the sampling rate in the A / D converter. However, when a digital beam former is realized, there is a problem that if a large number of high-speed A / D converters are used, the cost of the apparatus increases accordingly.
[0005]
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to constitute a digital beam former capable of sampling a high-frequency received signal without using a high-speed A / D converter. There is to do.
[0006]
Another object of the present invention is to provide an ultrasonic diagnostic apparatus suitable for both a normal ultrasonic probe and a high-frequency ultrasonic probe.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises an array transducer comprising a plurality of ultrasonic transducer elements and a plurality of A / D converters. In the double speed sampling mode, the number of A / D converters is n. In the normal sampling mode, simultaneous sampling clocks are supplied to each A / D converter in parallel in the A / D converter group divided into groups, and in the double-speed sampling mode, n types having the same frequency but different phases are supplied. Clock supply means for supplying one type of sampling clock to each group; means for setting connection relations between the plurality of ultrasonic vibration elements and the plurality of A / D converters; One A / D converter is connected to each ultrasonic vibration element to be operated, and in the double speed sampling mode, each ultrasonic vibration element to be operated is connected to each group. A switching circuit that connects n A / D converters one by one from the loop in parallel, and in the double-speed sampling mode, the n A / Ds connected in parallel for each of the operating ultrasonic transducers And a synthesizer group that collectively outputs received signals from the converter as one received signal.
[0008]
According to the above configuration, in the normal sampling mode, each A / D converter is used independently, and each received signal is sampled at a normal sampling rate as in the conventional case. On the other hand, in the double speed sampling mode, a plurality of A / D converters are divided into n groups, and sampling is performed in order by each group. That is, the phases of the sampling clocks supplied to each group are shifted from each other, and sampling is performed at different timings in each group. Here, n (n = 2, 3,...) A / D converters are allocated to one operating element, and sampling signals from these A / D converters are synthesized. Apparently, a sampling result equivalent to that sampled using the sampling clock of n times can be obtained.
[0009]
When the operating element group moves in the element array direction (when electronic scanning is performed), the correspondence relationship between the element and the A / D converter is also reset. In this case, one element is assigned to each element from each group. Each A / D converter is assigned.
[0010]
When n is 2, sampling is performed at double speed, and when n is 3, sampling is performed at triple speed. Incidentally, when the number of A / D converters is m, the number of elements that can be used at one time in the array transducer is m / n or less.
[0011]
In sector scanning using all elements for one reception, a normal sampling rate is applied, and linear scanning or convex linear scanning using only a part of elements for one reception is due to high frequency. If so, a double sampling rate is applied.
[0012]
According to the present invention, high-speed sampling can be realized by effectively using an available A / D converter without actually increasing the sampling rate of the A / D converter.
[0013]
In a preferred aspect of the present invention, the clock supply means includes a clock generator and a circuit that changes the phase of the clock generated by the clock generator to generate the n types of clocks. When n is 2, a clock shifted by ½ cycle can be generated simply by inverting the clock.
[0014]
A desirable mode of the present invention includes mode selection means for selecting the normal sampling mode or the double speed sampling mode according to the type of the ultrasonic probe used.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing a configuration of a receiving circuit. In FIG. 1, the transmission circuit is not shown.
[0017]
The array transducer 10 transmits and receives ultrasonic waves, and is composed of, for example, 128 elements. These elements are arranged linearly or arcuately. An ultrasonic beam is scanned by electronic scanning of the array transducer 10, thereby forming a two-dimensional data capturing area. In general, when electronic sector scanning is performed, all the elements are used simultaneously. On the other hand, when electronic linear scanning is performed, some elements are used at once, and the operating element group 200 is accompanied by electronic scanning. Shifted in the element array direction. The operating element group 200 forms a so-called reception aperture. Each element is supplied with a transmission signal from a transmission circuit, but is not shown.
[0018]
The switching circuit 12 is provided in the subsequent stage of the array transducer 10, and sets the correspondence between each element and each A / D converter. In the normal sampling mode, each element and each A / D converter are connected on a one-to-one basis. This is the same as before. On the other hand, when the double-speed sampling mode is applied, two A / D converters are assigned to one operating element. That is, two A / D converters operate in parallel for one element. However, in this case, the sampling timings of the A / D converters are shifted from each other by ½ period, and as a result, double-speed sampling is realized as described later.
[0019]
The receiver group 14 is composed of, for example, 128 receiving circuits. This receiving circuit is composed of, for example, an amplifier and a filter. Of course, the receiver group 14 may be provided before the switching circuit 12.
[0020]
The A / D converter group 16 includes, for example, 128 A / D converters. It is desirable that the number of A / D converters is at least larger than the total number of elements. In this embodiment, the same number of A / D converters as the number of elements are provided. In the normal sampling mode, one A / D converter is assigned to each element, that is, one to one is connected. On the other hand, in the double speed sampling mode, the A / D converter group 16 is divided into two groups, A group and B group, and the first pair of the A group and the first pair of the B group, the second group of the A group, Two A / D converters operate in parallel in a relationship such as the second pair of the B group. In the figure, since 128 A / D converters are provided, A / D converters 1 to 64 constitute an A group, and 65 to 128 A / D converters. Constitutes the B group.
[0021]
Therefore, the operating element group 200 is composed of at most 64 elements. For example, when the operating element group 200 is composed of 64 elements, the first A / D converter and the 65th A / D converter are always connected to the first element, and the second element is connected to the second element. On the other hand, the 2nd A / D converter and the 66th A / D converter are always connected. The same applies to the subsequent elements, and this correspondence is maintained even when the operating element group 200 is electronically scanned.
[0022]
In this embodiment, a normal sampling clock is supplied to the A / D converters of the A group, and a clock shifted by a ½ cycle is supplied to the A / D converters of the B group. These clocks are generated by the clock generator 20. The clock generator 22 generates a basic clock. The clock is supplied to the phase shifter 24, the selector 26, and each A / D converter of the A group. The phase shifter 24 executes a process of shifting the clock by ½ period. Specifically, the phase shifter 24 of this embodiment executes a process of inverting the clock. Therefore, the selector 26 receives a clock that is not shifted and a clock that is shifted by ½ period. The selector 26 selects a clock to be supplied to the B group based on a mode signal 100 output from a mode determination unit 54 described later. For example, when the normal sampling mode is selected, the selector 26 outputs the clock generated by the clock generator 22 as it is. As a result, clocks of the same phase are supplied to all A / D converters. On the other hand, when the mode signal 100 indicates the double speed sampling mode, the selector 26 selects the clock output from the phase shifter 24. As a result, a normal clock is supplied to the A group, but a clock shifted by ½ period is supplied to the B group.
[0023]
The switch group 18 is composed of, for example, 64 switches in the present embodiment. Each switch has a function of selecting two input signals. For example, when the normal sampling mode is selected, each switch continuously outputs the received signal output from the A group. On the other hand, when the double-speed sampling mode is designated, each switch switches and outputs the reception signal output from the A group and the reception signal output from the B group within one cycle of the sampling clock. As a result, a sampling signal equivalent to that obtained when the received signal is sampled at the double sampling rate can be obtained. This will be described in detail later.
[0024]
Therefore, when the normal sampling mode is designated, as shown by reference numeral 104, digital reception signals corresponding to the respective elements appear from all output lines. On the other hand, when the double-speed sampling mode is designated, a digital signal appears on the signal line corresponding to the operated element among the plurality of signal lines corresponding to the A group indicated by reference numeral 102. In this case, the rate of the digital signal is twice that of a normal one.
[0025]
The reception control unit 50 shown in FIG. 1 controls the operation of the entire reception circuit. The reception control unit 50 includes a mode determination unit 54 in the present embodiment. The probe type detection unit 52 is means for detecting the type of the probe connected to the ultrasonic diagnostic apparatus main body, and the detection result is input to the mode determination unit 54. Then, the mode determination unit 54 sets whether the sampling mode is the normal sampling mode or the double speed sampling mode based on the probe type. The probe type detection unit 52 reads, for example, a setting state of a dip switch preset in the ultrasonic probe at the time when the ultrasonic probe is connected, and based on that, it is a high-frequency probe or a normal probe It is determined whether it is a probe. The detection result of the probe type is also sent to a transmission control unit (not shown). For example, when a high frequency probe is detected, a higher frequency than usual is used as the transmission frequency.
Of course, in the present embodiment, the mode is automatically determined. However, the mode may be determined by the user and the mode designation may be input. As described above, the mode signal 100 is supplied to the clock generation unit 20 and to the switching circuit 12 and the switch group 18.
[0026]
FIG. 2 conceptually shows the states of the signals shown in (A) to (E) of FIG. The clock shown in (A) is a clock generated by the clock generator 22, and the clock shown in (B) is a clock output from the phase shifter 24. These clocks have the same period T1, but their phases are shifted by a half period.
[0027]
In the double speed sampling mode, a signal as shown in (C) is output from the A group, and a signal as shown in (D) is output from the B group. Then, by switching the switch circuit, a sampling signal equivalent to that sampled at the double speed as shown in (E) is obtained. In the normal sampling mode, signals as shown in (C) are output from both the A group and the B group.
[0028]
Receiving signals output from the receiving circuit are synthesized with their phases being digitally aligned, thereby forming a B-mode tomographic image, for example. Such phasing addition can be performed by hardware, but may be processed by software.
In the above embodiment, the A / D converter group 16 is divided into two groups, the A group and the B group. However, the grouping may be performed by three or more groups. For example, when it is divided into three groups, it is possible to obtain a 3 × speed sampling result.
[0029]
According to the above-described embodiment, it is possible to effectively use the idle A / D converter without using the high-speed A / D converter, thereby realizing high-speed sampling. Therefore, for example, there is an advantage that it can be applied to a high frequency linear probe.
[0030]
The present invention can also be applied to cases where the number of vibrating elements and A / D converters are different.
[0031]
【The invention's effect】
As described above, according to the present invention, a high frequency received signal can be sampled without using a high-speed A / D converter. Further, according to the present invention, it is possible to adapt to both a normal ultrasonic probe and a high-frequency ultrasonic probe.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a receiving circuit of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a timing chart showing the relationship between signals.
[Explanation of symbols]
10 array transducers, 12 switching circuits, 14 receiver groups, 16 A / D converter groups, 18 switch groups, 20 clock generators, 22 clock generators, 24 phase shifters, 26 selectors, 50 reception control units, 52 Probe type detection unit, 54 mode determination unit.

Claims (3)

An array transducer comprising a plurality of ultrasonic transducer elements;
An A / D converter group composed of a plurality of A / D converters, and in the double-speed sampling mode, these A / D converters are divided into n groups;
In normal sampling mode, simultaneous sampling clocks are supplied to each A / D converter in parallel. In double speed sampling mode, n types of sampling clocks with the same frequency but different phases are supplied to each group. Means,
A means for setting connection relations between the plurality of ultrasonic vibration elements and the plurality of A / D converters, and in the normal sampling mode, one A / D converter for each ultrasonic vibration element that operates. In the double-speed sampling mode, a switching circuit that connects n A / D converters, one from each group, in parallel for each operating ultrasonic vibration element, and
In the double-speed sampling mode, a synthesizer group that collectively outputs the received signals from the n A / D converters connected in parallel for each of the operating ultrasonic vibration elements as one received signal;
Only including,
In the double-speed sampling mode, the switching circuit resets the connection relationship between the plurality of ultrasonic vibration elements and the plurality of A / D converters each time the operating ultrasonic vibration element group is moved in the element arrangement direction. An ultrasonic diagnostic apparatus. The apparatus of claim 1.
The clock supply means includes
A clock generator;
A circuit for generating the n types of clocks by changing the phase of the clock generated by the clock generator;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
An ultrasonic diagnostic apparatus comprising mode selection means for selecting the normal sampling mode or the double speed sampling mode according to a type of an ultrasonic probe to be used.

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