JP2003164456A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the quality of ultrasonic images by extracting higher harmonic components from received signals prior to A/D conversion in a harmonic imaging mode and to eliminate a difference in passband characteristic between channels. <P>SOLUTION: A band-pass filter is provided for each channel, the band-pass filter having a resonant circuit having an inductor element L and a variable capacity circuit 70. By varying control voltages 104 and 106, the capacities of diodes D1 and D2 are controlled whereby the passband characteristics can be adjusted. <P>COPYRIGHT: (C)2003,JPO

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 that processes a plurality of received signals.

[0002]

2. Description of the Related Art In ultrasonic diagnostic equipment,
The plurality of reception signals output from the plurality of vibrating elements are input to the receiving circuit. The reception circuit includes a preamplifier, a variable gain amplifier, an A / D converter, and the like provided for each channel, and further includes a phasing addition circuit that adjusts and adds the phases of a plurality of reception signals. The received signal after phasing addition is
For example, it is input to the image forming circuit through a circuit such as a bandpass filter.

By the way, when performing harmonic imaging (imaging of higher harmonics), it is necessary to extract a desired band component from the received signal. for that reason,
In the past, a bandpass filter was provided after the receiving circuit, that is, after phasing addition, and the center frequency and the like were variable.

However, when the receiving circuit is configured as a digital beam former, that is, when the received signal of each channel is digitally converted before the phasing addition, the input dynamic range of the A / D converter is taken into consideration. It is necessary to adjust the gain of the received signal. In this case, the range of the entire received signal is adjusted to the input dynamic range of the A / D converter regardless of the range of the target frequency component that is finally required. There is a problem that the ratio cannot be improved.

Particularly, in recent years, when harmonic imaging has been put into practical use, it is desired to more effectively extract the harmonic component. However, the harmonic is a signal component that is considerably weaker than the fundamental wave. If the level is adjusted to the input dynamic range of the A / D converter, a sufficient dynamic range for harmonics cannot be secured.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to extract a target component for each channel prior to A / D conversion so that the dynamic range can be adjusted. It is in.

Another object of the present invention is to easily arrange the pass band characteristics of the band pass filter between the channels.

Another object of the present invention is to enhance the image quality of ultrasonic images (particularly harmonic imaging images).

[0009]

(1) In order to achieve the above-mentioned object, the present invention inputs and processes a plurality of received signals output from a plurality of vibrating elements, thereby forming an ultrasonic image. In the ultrasonic diagnostic apparatus, a plurality of band-pass filters individually provided for each of the vibrating elements,
A phasing addition circuit that is provided after the plurality of bandpass filters and performs phasing addition on the received signals that have passed through the plurality of bandpass filters, and adjusts the passband characteristics of each of the bandpass filters. And a control unit.

With the above arrangement, the received signal is input to the phasing addition circuit via the bandpass filter. The pass band characteristic of each band pass filter is set so as to extract a component necessary for forming an ultrasonic image. Actually, when there is a difference in the pass band characteristics (especially the resonance point) of each band pass filter due to the variation (or other factors) in the operating characteristics of the elements that compose it. Can be. According to the above configuration, each pass band characteristic can be adjusted (for example, uniformized) by coping with such variations, so that the image quality of the ultrasonic image can be improved. In the above adjustment, in addition to the fine adjustment of the pass band characteristic, the pass band characteristic may be switched (for example, fundamental wave extraction and harmonic wave extraction). The adjustment can be performed at the time of shipping or maintenance of the device, or manually or automatically as required.

Desirably, the control unit performs control for equalizing pass band characteristics between band pass filters or between band pass filter groups. A more ideal adjustment can be made by adjusting each bandpass filter, and adjusting between bandpass groups simplifies the circuit configuration for adjustment while achieving a certain adjustment effect. it can.

By the way, since the elements (especially the variable capacitance diode) manufactured adjacently in the manufacturing stage have the same operation characteristics, the manufacturing order of the elements in the order of the channel number is taken into consideration in consideration thereof. Considering this, it is desirable to select the element to be used in the circuit configuration. Assuming such an arrangement, it is desirable to make adjustments for each bandpass group.

Preferably, each of the band pass filters extracts a harmonic component from the received signal in the harmonic imaging mode. According to this configuration, the harmonic component is extracted from the received signal and B
You can create mode images.

Desirably, each of the band pass filters is provided before the A / D converter. According to this configuration,
Since the bandpass filter is provided in the preceding stage of the A / D converter, the input dynamic range of the A / D converter can be effectively used for the harmonic components, and the image quality of the ultrasonic image can be improved.

Desirably, it includes a switching means for switching whether each of the received signals is passed through each of the band pass filters or bypassed. According to this configuration, for example, when an ultrasonic image is formed by the fundamental wave (fundamental mode), the bandpass filter is used, while in the harmonic imaging mode, the received signal is input to the bandpass filter.

Preferably, each of the bandpass filters has a resonance circuit composed of an inductor element and a capacitor element, the capacitor element includes at least one diode to which a reverse bias voltage is applied, and the control unit has the inverse circuit. The pass band characteristic of each band pass filter is adjusted by varying the bias voltage. According to this configuration, the capacitance can be changed by changing the reverse bias voltage of the diode, and the passband characteristic can be adjusted by a simple method of changing the voltage.

Preferably, the capacitor element is composed of a pair of diodes connected in opposite directions to which a reverse bias voltage is applied, and the control unit varies the reverse bias voltage for each of the pair of diodes. According to this configuration, since the pair of diodes are connected in opposite directions, it is possible to form a sufficient capacitance while complementarily compensating for characteristic variations.

(2) Further, in order to achieve the above object,
The present invention, in an ultrasonic diagnostic apparatus for inputting and processing a plurality of received signals output from a plurality of vibrating elements, thereby forming an ultrasonic image, is provided for each vibrating element, an inductor element and a capacitor. A plurality of band-pass filters having a resonance circuit including a varicap diode circuit as an element, and a plurality of band-pass filters are provided in the subsequent stage, and phasing addition is performed on a reception signal that has passed through them. A phasing addition circuit to be executed, and a plurality of bias generators that are provided for each of a plurality of vibrating element groups set for the plurality of vibrating elements and that generate a reverse bias voltage for each group to be applied to each varicap diode circuit. And a circuit for adjusting the reverse bias voltage for each group generated by each of the bias generation circuits.

According to the above configuration, since adjustment can be performed in group units, adjustment can be performed in group units for all channels, and the circuit configuration can be simplified to reduce manufacturing cost.

(3) Further, in order to achieve the above object,
The present invention relates to an ultrasonic transducer that outputs a reception signal by transmitting an ultrasonic wave and receives a reflected wave, and a preamplifier that performs preamplification on the reception signal output from the ultrasonic transducer. A filter for extracting a harmonic component, the filter circuit receiving the reception signal output from the preamplifier, a variable gain amplifier for amplifying the reception signal output from the filter circuit, and the variable An A / D converter that converts the received signal output from the gain amplifier into a digital signal; an image forming circuit that forms a harmonic imaging image based on the received signal converted into a digital signal by the A / D converter;
A display for displaying the harmonic imaging image.

According to the above configuration, it is possible to extract the harmonic component from the received signal, adjust the gain of the received signal, and then input the received signal to the A / D converter. Therefore, in the harmonic imaging mode, the level of the harmonic component is raised (the gain is higher than in the case of fundamental wave imaging), and A
The input dynamic range of the / D converter can be effectively used. As a result, in the conventional configuration, it is possible to detect even a signal component of a level that has been excluded. That is, the signal detection limit can be lowered.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall structure thereof.

The probe 10 is an ultrasonic probe that transmits and receives ultrasonic waves. The probe 10 is used by being brought into contact with the surface of a living body or by being inserted into a body cavity. The probe 10 includes an array oscillator, which will be described later with reference to FIG. 2, and the array oscillator includes a plurality of vibrating elements. An ultrasonic beam is formed by the array transducer, and the ultrasonic beam is electronically scanned. Examples of the electronic scanning method include electronic linear scanning and electronic sector scanning.

The transmitting unit 12 functions as a transmitting beam former, and the transmitting unit 12 supplies a transmitting signal to each vibrating element forming the array transducer.

The receiving section 14 is a circuit which functions as a receiving beam former and performs a phasing addition process on a plurality of received signals output from a plurality of vibrating elements. The specific circuit configuration will be described later with reference to FIG. 2, but in the present embodiment, a band pass filter (BPF) is provided for each channel, and the pass band characteristic of each BPF is variable or adjusted. You can

The controller 16 controls the operation of each component in the apparatus, and the controller 16 is connected to an input section 18 constituted by an operation panel or the like.

The signal processing section 20 is a circuit for performing signal processing for forming a tomographic image and signal processing for forming a Doppler image. An ultrasonic image is formed by this signal processing, and the image information is displayed on the display unit 24 via the display processing unit 22.
Is output to. Various images such as a B mode and a color flow mapping image are displayed on the display unit 24 as ultrasonic images.

The ultrasonic diagnostic apparatus of this embodiment has a so-called harmonic imaging mode in addition to an image forming function using a normal fundamental wave. In the harmonic imaging mode, the harmonic component contained in the received signal is extracted, and an ultrasonic image is formed using the harmonic component. In that case, the harmonics are extracted by the receiving unit 14 shown in FIG.

FIG. 2 shows a concrete configuration example of the receiving section 14 shown in FIG.

The array vibrator 30 is composed of a plurality of vibrating elements 32 as described above.

The receiving section 14 is roughly classified into the preamplifier group 3
4, a BPF group 38, a variable gain amplifier group 44, an A / D converter group 48, a delay line (DL) group 52, an adder 56, and the like. Here, the delay line group 52
And the adder 56 constitutes a so-called phasing addition unit 51.

As shown in FIG. 2, the preamplifier group 34
Is composed of a preamplifier 36 provided for each channel, similarly, the BPF group 38 is composed of a BPF 40 provided for each channel, and the variable gain amplifier 44 is a variable gain amplifier provided for each channel. A / D converter group 4
8 is an A / D converter 50 provided for each channel
The DL group 52 is configured by the DL 54 provided for each channel.

Here, paying attention to one channel, the received signal output from the vibration element 32 is amplified by the preamplifier 36, and then the received signal is passed to the BPF4.
Input to 0. Then, after the reception signal is filtered in the BPF 40, the reception signal as its output signal is input to the variable gain amplifier 46. The variable gain amplifier 46 is a circuit that performs a desired amplification on the received signal, and the received signal after the amplification is A /
It is converted into a digital signal in the D converter 50. The received signal converted into the digital signal is subjected to delay processing in the DL 54, and the delayed received signal is output to the adder 56. That is, in the adder 56, a plurality of received signals that have been subjected to a predetermined delay process are added, and thereby the received signal after phasing addition is output to the subsequent stage.

In the present embodiment, a plurality of groups 42 are set for a plurality of BPFs 40 constituting the BPF group 38. For example, when there are channels 0 to N, n BPFs each from the 0th side configure each group 42, and thus k groups are configured. A bias generator 60 is provided for each group 42 of each BPF 40 in this embodiment. That is, each bias generator 60 supplies a control voltage as a bias signal described later to the corresponding group. Each bias generator 60 individually controls the bias voltage in units of groups, so that the passband characteristics for the received signal can be varied or adjusted for each group. With such a configuration, it is possible to improve the image quality of the ultrasonic image by suppressing the variation of the pass band characteristics (particularly the center frequency) of the entire channel within a certain range. Particularly, in the harmonic imaging mode, the target harmonic component is extracted more efficiently, and S /
There is an advantage that the N ratio can be improved to form a good ultrasonic image.

In FIG. 2, the bias generator 58 is composed of a plurality of bias generators 60. The reception control unit 62 adjusts the gain for each variable gain amplifier 46 and also controls the delay amount in each DL 54. In addition, in the present embodiment, the reception control unit 62 also controls the switching of pass band characteristics in each BPF 40 and whether or not to substantially filter the BPF 40 according to the operation mode of the device.

In the embodiment shown in FIG. 2, the pass band characteristic of each BPF 40 is adjusted in units of the group 42. However, of course, each BPF 40 is provided with a bias generator 60 and the pass band is individually set. The characteristics may be finely adjusted.

FIG. 3 shows an example of a concrete circuit configuration of the BPF 40 shown in FIG. This BPF40
Has a circuit module 72, and in the harmonic imaging mode, the filtered reception signal that has passed through the circuit module 72 is selected and output by the selector 74, while in the fundamental imaging mode, the circuit module 72 is The bypassed unfiltered received signal is selected by the selector 74 and output. That is, a bypass line 77 that bypasses the circuit module 72 and outputs the received signal 100 to the subsequent stage is provided. The selector 74 is composed of, for example, an analog switch or the like.

The circuit module 72 will be described below. The circuit module 72 has an input transistor Q1, a filter circuit 76, an output transistor Q2, etc., as shown in the figure. Here, the filter circuit 76 is
It constitutes a resonance circuit and has an inductor element (coil) L and a variable capacitance circuit 70. Variable capacitance circuit 70
The pass band characteristic of the present BPF 40 is adjusted by changing the capacitance at. The resistor R5 is mainly for adjusting the sharpness (Q value) of the pass band characteristic,
The capacitor C2 is mainly provided for DC cut. The received signal is input to the variable capacitance circuit 70 via the resistor R5 and the capacitor C2.

The variable capacitance circuit 70 constitutes a varicap diode circuit, and specifically, a pair of diodes (varicap diodes) connected in parallel in opposite directions.
It is composed of D1 and D2. A control voltage (positive voltage) 104 is applied as a reverse bias voltage to the anode side of the diode D1, and a control voltage (negative voltage) is applied to the cathode side of the diode D2 as a reverse bias voltage.
106 is being applied. Therefore, the voltage between the anode and the cathode of each diode D1, D2 can be changed to a desired value by the control voltage.

Here, each control voltage 104, 10
6 is generated by the bias generator 60 (FIG. 2) corresponding to the group to which the BPF 40 belongs. As described above, by adjusting the control voltages 104 and 106, the capacitance of the variable capacitance circuit 70 changes, and the pass band characteristic (mainly the center frequency) can be adjusted accordingly. If the diodes D1 and D2 are manufactured adjacent to each other in the manufacturing stage, the characteristics can be made uniform and a complementary compensation action can be obtained. In particular, each BPF4 in the same group
Regarding 0, it is desirable to consider so as to make the characteristics of each diode as uniform as possible. Of course, if a bias generator is provided for each BPF 40, such consideration is unnecessary. The control voltages 104 and 106 are variably controlled simultaneously or individually.

The transistor Q3 provided on the emitter side of the input transistor Q1 constitutes a part of the constant current circuit,
Bias current 102 is input to the base. The value of the bias current 102 is the same between the BPFs 40 and is fixed. However, the value of the bias current 102 can be adjusted for the constant current adjustment. A constant current source can be configured by using a resistor instead of the transistor Q3.

When the received signal 100 is input to the base of the input transistor Q1, the received signal appears as a voltage at its collector, and the received signal passes through the filter circuit 76. In the process, a signal component of a desired frequency band in the received signal is extracted according to the pass band characteristic of the filter circuit that constitutes the resonance circuit. In the present embodiment, the harmonic component is extracted, and the received signal including the component is input to the base of the output transistor Q3. Then, a received signal appears on the emitter side of the output transistor Q3, and the received signal appears via the DC cut capacitor C3 in the selector 6
4 is input. The resistors R1, R3, R4, R6,
R7, R8 and capacitors C1, C4, C5, C6, C
Reference numerals 7 and C8 are for defining the operating conditions of the circuit.

The configuration of FIG. 3 is merely an example, and various circuit configurations can be used as long as the pass band characteristic can be adjusted by the variable capacitance. When forming an image with the fundamental wave, the center frequency of the pass band characteristic may be adjusted to the frequency of the fundamental wave instead of the bypass switching of the received signal 100 to the circuit module 72. According to such a configuration, unnecessary signal components are removed,
There is an advantage that the S / N ratio can be improved. Further, the pass band characteristic may be dynamically changed according to the depth of the receiving point. Further, when configuring the variable capacitance circuit, only one diode may be used, or more diodes may be used.

[0045]

As described above, according to the present invention,
The quality of the ultrasonic image can be improved.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a specific configuration example of a receiving unit shown in FIG.

3 is a circuit diagram showing a specific circuit configuration example of the BPF shown in FIG.

[Explanation of symbols]

10 probes, 12 transmitters, 14 receivers, 16
Controller, 20 signal processing unit, 22 display processing unit, 2
4 display section, 40 BPF, 42 BPF group, 6
0 bias generator, 62 reception control unit, 70 variable capacitance circuit, 72 circuit module, 74 selector.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4C301 AA02 BB01 BB02 BB23 CC02                       DD02 EE07 EE13 GB02 HH32                       HH48 HH60 JB03 JB11 JB29                       JB38 JB42 KK02 KK22                 4C601 BB05 BB06 BB07 BB21 BB23                       DE01 EE04 EE11 GB01 GB03                       HH26 HH35 HH40 JB01 JB02                       JB11 JB19 JB28 JB31 JB33                       JB34 JB45 KK02 KK12 KK18                       KK19                 5D019 FF04

Claims (9)

[Claims] 1. An ultrasonic diagnostic apparatus for inputting and processing a plurality of reception signals output from a plurality of vibrating elements to thereby form an ultrasonic image, wherein each vibrating element is provided individually. A plurality of bandpass filters, a phasing addition circuit that is provided after the plurality of bandpass filters, and performs a phasing addition on the received signals that have passed through the plurality of bandpass filters, and each of the bandpass filters An ultrasonic diagnostic apparatus comprising: a control unit that adjusts pass band characteristics of the. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the control unit performs control for equalizing pass band characteristics between band pass filters or between band pass filter groups. 3. The ultrasonic diagnostic apparatus according to claim 1, wherein each of the band pass filters extracts a harmonic component from a received signal in a harmonic imaging mode. 4. The ultrasonic diagnostic apparatus according to claim 1, wherein each of the bandpass filters is provided in front of an A / D converter. 5. The ultrasonic diagnostic apparatus according to claim 1, further comprising switching means for switching whether each of the received signals is passed through each of the bandpass filters or bypassed. 6. The receiving circuit according to claim 1, wherein each of the bandpass filters includes a resonance circuit including an inductor element and a capacitor element, and the capacitor element includes at least one diode to which a reverse bias voltage is applied. The ultrasonic diagnostic apparatus according to claim 1, wherein the control unit adjusts a pass band characteristic of each of the band pass filters by varying the reverse bias voltage. 7. The receiving circuit according to claim 6, wherein the capacitor element is composed of a pair of diodes connected to each other in reverse directions to which a reverse bias voltage is applied, and the control unit is configured to include each of the pair of diodes. The receiving circuit of the ultrasonic diagnostic apparatus, wherein the reverse bias voltage is varied. 8. An ultrasonic diagnostic apparatus for inputting and processing a plurality of received signals output from a plurality of vibrating elements to thereby form an ultrasonic image, wherein each of the vibrating elements is provided with an inductor element. A plurality of bandpass filters having a resonance circuit configured to include a varicap diode circuit as a capacitive element, and a phasing addition for a received signal that has been provided in a stage subsequent to the plurality of bandpass filters and has passed through them. A phasing addition circuit that executes the above, and a plurality of biases that are provided for each of the plurality of vibrating element groups set for the plurality of vibrating elements and that generate a reverse bias voltage for each group to be applied to each varicap diode circuit. And a reverse bias voltage for each group generated by each bias generation circuit. Diagnostic equipment. 9. An ultrasonic transducer that outputs a reception signal by transmitting an ultrasonic wave and receiving a reflected wave, and performs pre-amplification on the reception signal output from the ultrasonic transducer. A preamplifier, a filter for extracting a harmonic component, a filter circuit to which the received signal output from the preamplifier is input, a variable gain amplifier that amplifies the received signal output from the filter circuit, and the variable gain amplifier An A / D converter that converts the received signal output from the digital signal into a digital signal, an image forming circuit that forms a harmonic imaging image based on the received signal converted into the digital signal by the A / D converter, and the harmonic An ultrasonic diagnostic apparatus comprising: a display for displaying an imaging image;