JP2002085402A - Ultrasonic diagnostic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove offset components generated in A/D converters provided at every channel in ultrasonic diagnostic equipment provided with a digital beam former(DBF). SOLUTION: In a state where offset correcting circuits 16 are provided at every channel and the inputs of the A/D converters 14 are grounded, an offset component is specified by averaging the outputs of the converters 14 and a subtracter 30 subtracts the offset component from received signals. It is also possible to adjust the reference voltages of the converters 14 by utilizing the offset component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to a receiving circuit of an ultrasonic diagnostic apparatus having a digital beamformer.

[0002]

2. Description of the Related Art A digital beamformer (DBF) executes phasing addition after performing digital conversion of a received signal for each vibrating element. A /
Although there are various types of D converters, usually, a comparison between a reference voltage and an input signal is performed.

When an offset component (DC component) is generated in the A / D converter, accurate signal addition cannot be performed, and the dynamic range of each circuit provided at a subsequent stage of the A / D converter is effectively narrowed. In particular, at the time of reception, the transmission / reception aperture is variably controlled continuously or stepwise in conjunction with the reception dynamic focus, but in this case, the sum of offset components differs due to the difference in the number of additions. On the other hand, there is a problem that a discontinuous line or the like appears on a portion of the image corresponding to the change of the transmission / reception aperture.

Of course, by adjusting the A / D converter,
Although it is possible to make the offset component close to zero, the number of channels is very large in the DBF, and a great effort is required to perform perfect adjustment for each A / D converter. It is also conceivable to insert a filter that cuts the DC component at the subsequent stage of the A / D converter, but a relatively large circuit is provided to cut only the DC component without damaging the necessary frequency components. Required, leading to increased costs.

[0005] The offset component is generally remarkable in an A / D converter, but can also occur in circuits and elements other than the A / D converter.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to improve the image quality of an ultrasonic image by excluding an offset component generated by an A / D converter or the like.

Another object of the present invention is to cancel offset components and other error factors generated in an A / D converter or the like with a simple configuration, particularly in a DBF.

[0008]

Means for Solving the Problems (1) In order to achieve the above object, the present invention provides a vibrating element for outputting a reception signal,
A signal processing circuit that performs predetermined processing on the received signal, an offset detection unit that detects an offset component included in an output signal of the signal processing circuit, and an output signal of the signal processing circuit according to the offset component. And an offset correction unit for performing correction.

According to the above configuration, it is possible to detect the offset component included in the output signal output from the signal processing circuit, and execute a process of removing the offset component according to the detected offset component. The above signal processing circuit is an A / D converter, a preamplifier provided in the preceding stage, and other circuits. For example, if an offset component is detected for a digital signal output from an A / D converter, an offset component generated by a series of signal processing circuits including the A / D converter (transmission via a vibrating element) (A wraparound offset component from the circuit side may be included).

Preferably, the offset detecting means includes:
The offset component is specified in accordance with an output signal output when the signal processing circuit receives no signal. Since the output signal when no signal is input can be regarded as the offset component itself, the offset component is detected therefrom.

Preferably, the offset detecting means includes:
The offset component is specified according to an output signal of the signal processing circuit in a state where an input of the vibration element is grounded. According to this configuration, unnecessary signal components can be excluded from the received signal, including the wraparound offset component from the transmission circuit side.

Preferably, at least two ground switching points in a path from the input of the vibrating element to the signal processing circuit are selectively grounded, and the offset detecting means is configured to detect the ground switching state at each ground switching point. Specify the offset component. According to this configuration, any circuit, element,
It is also possible to trace how much the offset component is generated at the route point, which is useful for finding the cause. Therefore, there is an advantage that the device maintenance can be performed more accurately.

Preferably, the offset correction means comprises:
The output signal of the signal processing circuit is corrected. Preferably,
The offset correction unit corrects an operation condition of the signal processing circuit. In this way, the removal of the offset component may be performed ex post on the output signal itself,
The adjustment may be performed in advance by adjusting the operation of the circuit itself that generates the offset component.

(2) In order to achieve the above object,
The present invention provides an A / D converter for converting a received signal from a vibration element into a digital signal, an offset detecting means for detecting an offset component included in a digital signal output from the A / D converter, And offset correction means for executing processing for excluding components.

According to the above arrangement, the offset correcting means performs a process of actually detecting an offset component (DC component) generated in the A / D converter and excluding the offset component based on the offset component. Therefore, unnecessary components can be automatically removed, and the image quality of the ultrasonic image can be improved without requiring complicated manual adjustment. In particular, the dynamic range of each circuit after the A / D converter can be effectively used. INDUSTRIAL APPLICABILITY The present invention is applicable to both an ultrasonic diagnostic apparatus having an ultrasonic probe having a single transducer and an ultrasonic diagnostic apparatus having an ultrasonic probe having an array transducer. In addition, various methods can be adopted for removing or correcting the offset component. The removal of the offset component is ideal before the phasing addition, but a certain effect can be obtained even if the offset component is removed after the phasing addition. Note that an offset correction unit may be inserted between the delay unit and the phasing adder.

Preferably, the offset detecting means comprises:
The offset component is specified according to a digital signal output when no signal is input to the A / D converter. Since the signal output from the A / D converter when no signal is input can be regarded as an offset component, the offset component is detected using the signal.

Preferably, the offset detecting means comprises:
An average value is calculated for the digital signal output when no signal is input to the A / D converter, and the average value is used as the offset component. According to this configuration, even if the level of the offset component fluctuates with time, signal correction can be performed accurately using the average value.

Preferably, the apparatus further includes ground switching means provided before the A / D converter and connecting a ground to an input of the A / D converter instead of a reception signal path. The offset component is specified with the ground connected to the input of the A / D converter.
If you positively connect the ground to the input of the A / D converter,
The offset component can be accurately detected without being affected by external factors such as noise.

Preferably, the detection of the offset component and the correction based on the offset component are performed in a blank period between reception periods. If the offset correction is performed in such a transmission period, the idle time can be used effectively and the correction can be continuously performed, so that accurate measurement conditions can always be realized. However, it is desirable to connect a required portion on the signal path to the ground in order to prevent the influence of the transmission signal sneaking and leakage.

Preferably, the detection of the offset component is executed when the apparatus is started. Preferably, the detection of the offset component is performed at the time of device adjustment.

(3) To achieve the above object,
The present invention provides a plurality of vibration elements, a plurality of A / D converters provided for each of the vibration elements, and a plurality of A / D converters for converting a received signal from the vibration element into a digital signal, and a plurality of A / D converters provided for each of the A / D converters A plurality of offset detecting means for detecting an offset component included in a digital signal output from each A / D converter; and a plurality of offset correcting means for executing a process of removing each offset component by each of the offset components. And an adder for adding a plurality of digital signals from which the offset component has been removed.

According to the above configuration, there is an advantage that offset correction can be easily performed in the DBF regardless of the number of channels.

(4) To achieve the above object,
The present invention provides an A / D converter for converting a received signal from a vibration element into a digital signal, an offset detecting means for detecting an offset component by the A / D converter, and the A / D converter based on the offset component. And an offset correcting means for adjusting the operation of (1). According to this configuration, without directly correcting the received signal, A
The adjustment of the / D converter itself (for example, the adjustment of the reference voltage) can be performed so that the dynamic range can be effectively used to the maximum.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a main configuration of an ultrasonic diagnostic apparatus according to the present invention. FIG. 1 shows a detailed configuration of a receiving unit in the ultrasonic diagnostic apparatus.

The vibrating element 10 is an element for transmitting and receiving ultrasonic waves. A plurality of vibrating elements 10 constitute a so-called array vibrator. However, the present invention is also applicable to a case where a single oscillator is provided. A circuit for processing a received signal is provided for each vibration element 10.

More specifically, each vibrating element 10, that is, an amplifier 12 for amplifying a received signal for each channel
And an A / D converter 14 for converting a received signal from an analog signal to a digital signal, an offset correction circuit 16, and a delay unit 18. The output of the delay unit 18 is input to an adder 20. I have.

That is, the ultrasonic diagnostic apparatus according to the present embodiment has a receiving section as a digital beamformer as shown in FIG. A delay unit 14 is provided, and delay addition is performed on the digital signal. Incidentally, the configuration of the transmission circuit is not shown in FIG.
Also, control signals input to each circuit are not shown except for a part.

The received signal (combined received signal) output from the adder 20 is input to, for example, a circuit for forming a B-mode image or a circuit for performing Doppler signal processing. These circuits are known.

The offset correction circuit 16 will be described in detail. A received signal output from the A / D converter 14 is input to one input terminal of a subtractor 30, and the received signal is input to one input terminal of an adder 24. Input to terminal. A flip-flop circuit 26 is connected to the other input terminal of the adder 24.
Is output as a feedback signal and the adder 24
Adds the two input signals and outputs the result to the flip-flop circuit 26. The flip-flop circuit 26 functions as a memory, adds the output of the adder 24 within a certain period, and outputs the added value to the 1 / N circuit 28. The 1 / N circuit 28 is a circuit that divides the addition result by the numerical value N, and the value after the division, that is, the average value is input to the other input terminal of the subtractor 30. Here, the average value corresponds to the offset component of the A / D converter 14.

The subtracter 30 subtracts the offset component obtained as described above from the received signal output from the A / D converter 14, and outputs the subtracted received signal to the delay unit 18.
Output to

When the offset component of the A / D converter 14 is specified, the switch 22 is switched from the terminal A to the terminal B in the present embodiment.
The input of the A / D converter 14 is connected to the ground.
That is, at the time of such no-signal input, the output signal output from the A / D converter 14 is presumed to be exactly an offset component. Therefore, such an offset component is sampled by N clocks, and these are sampled. The offset component as an average value is specified by averaging. Then, when processing the actual received signal, the switch 22 is switched from the B side to the A side, and the offset component is subtracted from the received signal.

Incidentally, the above circuit configuration is provided for each channel, but FIG. 1 typically shows only a reception signal processing circuit for one channel.

FIG. 2 is a timing chart showing the above-mentioned operation. In FIG. 2, (A) shows transmission / reception timing. As shown in FIG. The transmission period has been set. In other periods, a reception signal is obtained as shown in FIG.

In this embodiment, the correction value clear signal 102 is output at the beginning of the transmission blank period as shown in FIG.
The stored value of 6 has been cleared. And (D)
In the correction value addition period, as shown in FIG.
Are switched and the A / D converter 1 is connected to the ground and the A / D converter 1 for N clocks.
4 are added. The result of the addition is calculated by the 1 / N circuit 28 as described above, and the offset component as an average value is specified.

In the above embodiment, the offset component is specified using the transmission blank period. For example, the offset component is detected only when the device is shipped, and the correction value is determined. It is also possible to store it in a memory. Similarly, the above process may be performed only at the time of maintenance. Further, the above-described offset component may be automatically detected when the power of the apparatus is turned on.

By the way, in the embodiment shown in FIG. 1, the offset component is directly subtracted from the received signal in the subtractor 30. For example, as shown by the broken line in FIG. The component may be used as a correction value and used for adjusting the reference voltage in the A / D converter 14. According to such a configuration, the operating characteristics of the A / D converter 14 can be feedback-adjusted, and the dynamic range can be effectively used as much as possible. Further, according to such a configuration, the subtractor 30 is not required, and it is considered that there is an advantage also in the circuit configuration.

In any case, by performing the processing for eliminating the offset component as described above, the image quality of the ultrasonic image can be improved, and the complicated adjustments required for maintenance can be eliminated. Becomes

The offset correction circuit 16 shown in FIG. 1 can be provided, for example, between the delay unit 18 and the adder 20. The offset correction circuit 16 accumulates the offset component for each channel and performs offset correction on the output of the adder 20. It is also possible to do.

FIG. 3 shows the configuration of another embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, each vibrating element 10
A transmission circuit 40 is connected to the input of the control signal, and a switch 42 is provided between each vibration element 10 and each transmission circuit 40. When the switch 42 is set to the A terminal side, the transmission circuit 40 is connected to the vibrating element 10 and the switch 4
When 2 is on the B terminal side, the ground is connected to the vibration element 10. That is, in this case, the input side of the vibration element 10 is grounded.

When detecting the offset component and performing the offset correction, the switch 22 or the switch 42 is selectively operated, and the selected switch grounds the path point. When only the switch 42 is switched to the terminal B side,
The output of the A / D converter 14 includes an offset component generated by the A / D converter 14, an offset component generated by the preamplifier 12, and an offset component generated by the vibration element 10 or sneaking from the input side thereof. Are all synthesized. Therefore, if all the offset components are detected by the offset correction circuit 16, the offset correction circuit 16 can collectively exclude such all offset components.

When the switch 22 is switched to the terminal B side, the offset component generated only by the A / D converter 14 can be specified as described above. Therefore, by selectively operating the two switches 22 and 42, it is possible to analyze which circuit on the signal path generates the offset component and to what extent. A switching signal 100 is input to the switch 22 and a switching signal 104 is input to the switch 42 from a control circuit (not shown), and each switch performs a switching operation according to the switching signals. Therefore, the selective switching control of the two switches 22 and 42 can be automated.

In the above embodiment, the vibration element 10
The ground switching point is formed on the input side of a desired circuit for checking whether or not an offset component is generated. Further, three or more ground switching points may be provided on a series of paths so that the cause of the occurrence of the offset component can be determined in more detail.

[0045]

As described above, according to the present invention,
There is an advantage that the problem inherent in the A / D converter can be solved and the image quality of the ultrasonic image can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 2 is a timing chart for explaining the operation of the circuit configuration shown in FIG.

FIG. 3 is a block diagram illustrating a configuration according to another embodiment.

[Explanation of symbols]

10 vibration element, 12 amplifier, 14 A / D converter,
16 offset correction circuit, 18 delay unit, 20 adder, 22, 42 switch, 24 adder, 26 flip-flop circuit, 28 1 / N circuit, 30 subtractor,
40 Transmission circuit.

Claims (15)

[Claims] A vibrating element that outputs a received signal; a signal processing circuit that performs a predetermined process on the received signal; and an offset detection unit that detects an offset component included in an output signal of the signal processing circuit. An ultrasonic diagnostic apparatus comprising: an offset correction unit configured to correct an output signal of the signal processing circuit according to the offset component. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein said offset detecting means specifies said offset component in accordance with an output signal output when no signal is input to said signal processing circuit. 3. The apparatus according to claim 1, wherein said offset detecting means specifies said offset component according to an output signal of said signal processing circuit in a state where an input of said vibrating element is grounded. Diagnostic device. 4. The apparatus according to claim 1, wherein at least two ground switching points in a path from an input of the vibrating element to the signal processing circuit are selectively grounded, and the offset detecting means includes a ground switch. An ultrasonic diagnostic apparatus characterized in that the offset component is specified in a ground state of a switching point. 5. An ultrasonic diagnostic apparatus according to claim 1, wherein said offset correction means corrects an output signal of said signal processing circuit. 6. The ultrasonic diagnostic apparatus according to claim 1, wherein said offset correction means corrects an operation condition of said signal processing circuit. 7. An A / D converter for converting a received signal from a vibrating element into a digital signal, an offset detecting means for detecting an offset component included in the digital signal from the A / D converter, and an offset component An ultrasonic diagnostic apparatus comprising: an offset correction unit configured to execute a process of excluding the following. 8. An ultrasonic diagnostic apparatus according to claim 7, wherein said offset detecting means specifies said offset component in accordance with a digital signal output when no signal is input to said A / D converter. apparatus. 9. The apparatus according to claim 8, wherein said offset detecting means calculates an average value of a digital signal output when no signal is input to said A / D converter, and calculates the average value as said offset. An ultrasonic diagnostic apparatus characterized by comprising a component. 10. The apparatus according to claim 8, wherein ground switching means provided before the A / D converter and connecting a ground to an input of the A / D converter instead of a reception signal path is provided. The ultrasonic diagnostic apparatus, wherein the offset detection unit specifies the offset component in a state where a ground is connected to an input of the A / D converter. 11. The ultrasonic diagnostic apparatus according to claim 1, wherein the detection of the offset component is performed during a blank period between reception periods. 12. The ultrasonic diagnostic apparatus according to claim 1, wherein the detection of the offset component is executed when the apparatus is started. 13. The ultrasonic diagnostic apparatus according to claim 1, wherein the detection of the offset component is performed at the time of adjusting the apparatus. 14. A plurality of vibrating elements, a plurality of A / D converters provided for each of the vibrating elements, for converting a received signal from the vibrating element to a digital signal, and for each of the A / D converters. A plurality of offset detecting means for detecting an offset component included in a digital signal from each of the A / D converters; and a process for eliminating an offset component included in the digital signal from each of the A / D converters An ultrasonic diagnostic apparatus comprising: a plurality of offset correction means for performing a correction; and an addition means for adding a plurality of digital signals from which the offset component has been removed. 15. An A / D converter for converting a signal received from a vibrating element into a digital signal, an offset detecting means for detecting an offset component included in a digital signal output from the A / D converter, An ultrasonic diagnostic apparatus comprising: an offset correction unit that adjusts the operation of the A / D converter by using an offset component.