Ultrasonic imaging system and signal noise reduction method

Abstract

This application provides an ultrasound imaging system and signal noise reduction method. The ultrasound imaging system includes a driver circuit board, a flexible circuit board, and an ultrasonic sensor. The driver circuit board provides a drive signal to the ultrasonic sensor via the flexible circuit board. The flexible circuit board is provided with a noise reduction circuit for filtering out noise from the drive signal. The technical solution of this application can filter out noise from the drive signal and improve the quality of ultrasound imaging.

Description

Technical Field

[0001] The present application relates to the field of ultrasonic imaging technology, and in particular to an ultrasonic imaging system and a signal noise reduction method. Background Art

[0002] Existing ultrasonic imaging systems typically use a driver circuit board to provide drive signals to the ultrasonic sensor via an FPC (Flexible Printed Circuit). Both the driver circuit board and the FPC are equipped with drive signal traces. The drive signal traces are typically very long, with the shortest drive signal trace exceeding 12 cm (centimeters), and the line spacing between adjacent drive signal traces is only 60 μm (micrometers). This line length and line spacing easily generate parasitic capacitance, which introduces noise. This in turn increases the noise input to the ultrasonic sensor, causing the data collected by the ultrasonic sensor to become noisier, affecting the quality of ultrasonic imaging. Summary of the Invention

[0003] The present invention provides an ultrasonic imaging system and a signal noise reduction method to solve the problems existing in the related art. The technical solutions are as follows:

[0004] In a first aspect, an embodiment of the present application provides an ultrasonic imaging system, comprising: a driving circuit board, a flexible circuit board, and an ultrasonic sensor;

[0005] The driving circuit board is used to provide a driving signal to the ultrasonic sensor through the flexible circuit board;

[0006] A noise reduction circuit is provided on the flexible circuit board, and the noise reduction circuit is used to filter out noise in the driving signal.

[0007] In a second aspect, an embodiment of the present application provides a signal noise reduction method, which is applied to the ultrasound imaging system provided in an embodiment of the present application. The signal noise reduction method includes:

[0008] The noise reduction circuit on the flexible circuit board is used to reduce the noise of the driving signal output by the driving circuit board.

[0009] The advantages or beneficial effects of the above technical solution include at least:

[0010] The ultrasonic imaging system provided in the embodiment of the present application can filter out the noise in the driving signal through the noise reduction circuit, effectively reduce the noise input to the ultrasonic sensor, and further reduce the noise in the data collected by the ultrasonic sensor, thereby effectively improving the quality of ultrasonic imaging.

[0011] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present application will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0013] Figure 1 A schematic diagram of the cross-sectional structure of an ultrasonic sensor in the related art and the principle of transmitting ultrasonic waves;

[0014] Figure 2 A schematic diagram of the cross-sectional structure of an ultrasonic sensor in the related art and the principle of receiving echo signals;

[0015] Figure 3 A schematic diagram of the cross-sectional structure and working principle of another ultrasonic sensor in the related art;

[0016] Figure 4 A schematic diagram of the wiring length in an ultrasound imaging system in the related art;

[0017] Figure 5 A schematic diagram of the structural framework of an ultrasound imaging system provided in an embodiment of the present application;

[0018] Figure 6 A schematic diagram of the structural framework of another ultrasound imaging system provided in an embodiment of the present application;

[0019] Figure 7 Schematic diagram of a circuit principle of a driving circuit in an embodiment of the present application;

[0020] Figure 8 is a schematic diagram of the connection relationship between the power signal line and the pixel circuit array;

[0021] Figure 9 A schematic diagram of the connection relationship between the control signal line and the pixel circuit array;

[0022] Figure 10 This is a schematic diagram of the wiring of the actual ultrasound imaging system;

[0023] Figure 11 Schematic diagram of a low-pass filter formed by decoupling capacitors and drive signal lines;

[0024] Figure 12This is a schematic diagram of the circuit principle of the sensor unit in the ultrasonic sensor;

[0025] Figure 13 Schematic diagram of the timing of each driving signal in the embodiment of the present application;

[0026] Figure 14 A schematic diagram of the structural framework of another ultrasound imaging system provided in an embodiment of the present application;

[0027] Figure 15 Schematic diagram of the application scenario of large-size ultrasonic sensors;

[0028] Figure 16 Schematic diagram of a portion of the equivalent circuit of an ultrasonic imaging system without decoupling capacitors in a noise reduction simulation test of a DC drive signal;

[0029] Figure 17 for Figure 16 Schematic diagram of the curve showing the voltage at the test point changing with time;

[0030] Figure 18 A schematic diagram of a partial equivalent circuit of an ultrasonic imaging system equipped with decoupling capacitors in a noise reduction simulation test of a DC drive signal;

[0031] Figure 19 for Figure 18 Schematic diagram of the curve showing the voltage at the test point changing with time;

[0032] Figure 20 A schematic diagram of a partial equivalent circuit of an ultrasonic imaging system without decoupling capacitors in a noise reduction simulation test of an AC drive signal;

[0033] Figure 21 for Figure 20 Schematic diagram of the curve showing the voltage at the test point changing with time;

[0034] Figure 22 A schematic diagram of a partial equivalent circuit of an ultrasonic imaging system equipped with decoupling capacitors in a noise reduction simulation test of an AC drive signal;

[0035] Figure 23 for Figure 22 Schematic diagram of the curve showing the change of test point voltage over time. DETAILED DESCRIPTION

[0036] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0037] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0038] First, the principles of the relevant technologies involved in the embodiments of this application are introduced as follows:

[0039] The principle of an ultrasonic imaging system is to scan a target object with an ultrasonic beam and obtain an image of the target by receiving and processing the echo signal generated by the target's reflection of the ultrasonic wave. Both the emission of the ultrasonic wave and the reception of the echo signal are performed by the ultrasonic sensor.

[0040] A structure and working principle of ultrasonic sensor Figure 1 and Figure 2 As shown, the ultrasonic sensor includes a first electrode (also called an upper electrode or upper end electrode), a second electrode (also called a lower electrode or lower end electrode), and a piezoelectric layer located between the first and second electrodes. The piezoelectric material in the piezoelectric layer can be a PVDF (polyvinylidene fluoride) film piezoelectric material, or other inorganic or organic piezoelectric materials such as AlN (aluminum nitride), PZT (lead zirconate titanate piezoelectric ceramic), or ZnO (zinc oxide).

[0041] Reference Figure 1 The first electrode and the second electrode can be connected to an AC (alternating current) voltage. For example, one end of the first electrode can be connected to an AC square wave, and the other end can be grounded ( Figure 1 The ground terminal is not shown in the figure), one end of the second electrode is connected to the AC square wave, and the other end can be grounded ( Figure 1 When the first electrode and the second electrode are both connected to an AC voltage, the piezoelectric material layer between the first electrode and the second electrode will deform, or the piezoelectric material layer will drive the substrates of the upper and lower membrane layers ( Figure 1 The ultrasonic sensor vibrates together with the ultrasonic wave, thereby generating ultrasonic waves and transmitting them out. If there is an air cavity under the ultrasonic sensor, the ultrasonic waves can be strengthened and transmitted out better.

[0042] Reference Figure 2 When the ultrasonic wave is reflected by the target object to the piezoelectric layer, it will be converted into AC voltage by the piezoelectric layer. The second electrode serves as the receiving end to receive the AC voltage, and the first electrode is grounded ( Figure 2 The ground terminal is not shown).

[0043] Another structure and working principle of ultrasonic sensor is as follows Figure 3 As shown, the ultrasonic sensor includes: a glass substrate, a TFT (Thin Film Transistor) layer, a receiving electrode Rx, a PVDF film, an Ag (silver) layer (as a transmitting electrode) and a PZT sound source. The PZT sound source can emit an ultrasonic signal with high energy, which is reflected by the target object to the receiving electrode Rx.

[0044] Ultrasonic imaging systems can be used in the medical field to realize medical ultrasonic imaging. For example, the ultrasonic focused beam of an ultrasonic sensor is used to scan human tissue and then obtain a focused image based on the echo signal. Since the focused beam is narrow, the focused image obtained from each scan is in the form of a line. The focused images obtained from multiple scans can be spliced ​​into a two-dimensional image, and then the probe can be moved in a direction perpendicular to the two-dimensional image to scan and form a three-dimensional image.

[0045] The inventors of this application have found in their research that the driving circuit board is a PCB (Printed Circuit Board) provided with a driving circuit. The driving circuit board can provide a variety of driving signals, such as a power supply signal Vdd, a bias signal Vbias, a reset signal Vrst, a control signal Vclose, and a gate drive signal Gate, which can be transmitted to the ultrasonic sensor through the traces on the driving circuit board (hereinafter referred to as PCB traces) and the traces on the flexible circuit board (hereinafter referred to as FPC traces). The trace length of each driving signal is as follows: Figure 4 As shown. Figure 4 For the bias signal Vbias, reset signal Vrst, and control signal Vclose, the PCB trace length is 5 cm, the FPC trace length is 7 cm, and the total length is 12 cm; for the power signal Vdd, the PCB trace length is 10 cm, the FPC trace length is 7 cm, and the total length is 17 cm; for the gate drive signal Gate, the PCB trace length is 3 cm, the FPC trace length is 20 cm, and the total length is 23 cm.

[0046] Depend on Figure 4 From the data, we can see that the length of each drive signal from the output end to the ultrasonic sensor is relatively long, with the shortest trace length reaching 12cm. In the current ultrasonic simulation application scenario, it is necessary to test below 5cm underwater, and the drive circuit needs to be on the water surface. Therefore, the trace length of the drive signal cannot be shortened, otherwise the test requirements cannot be met. In addition, in the related art, the line spacing between adjacent traces in the flexible circuit board is only 60μm. With long traces and short spacing, the traces are very likely to couple into noise, including conducted noise and radiated noise, which will affect the quality of the drive signal and thus increase the noise of the pixel circuit acquisition signal in the ultrasonic sensor.

[0047] The following describes in detail the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems with specific embodiments.

[0048] The present application embodiment provides an ultrasonic imaging system, such as Figure 5 As shown, the system includes a driver circuit board 510, a flexible circuit board 520, and an ultrasonic sensor 530. The driver circuit board 510 is used to provide a driving signal to the ultrasonic sensor 530 via the flexible circuit board 520. The flexible circuit board 520 is provided with a noise reduction circuit 521 for filtering out noise in the driving signal.

[0049] The ultrasonic imaging system provided in the embodiment of the present application can filter out the noise in the driving signal through the noise reduction circuit, effectively reduce the noise input to the ultrasonic sensor, and further reduce the noise in the data collected by the ultrasonic sensor, thereby effectively improving the quality of ultrasonic imaging.

[0050] Optionally, multiple driving circuits are provided on the driving circuit board 510, and multiple driving signal lines are provided on the flexible circuit board 520; the first end of the driving signal line is electrically connected to the corresponding driving circuit, and the second end is electrically connected to the ultrasonic sensor 530; the third end of at least one driving signal line is electrically connected to the corresponding noise reduction circuit 521, and the distance between the second end and the third end of the driving signal line is within a preset distance range.

[0051] The distance range can be set according to actual needs or empirical values, for example, it can be 5cm (centimeter) to 10cm, so that the noise reduction circuit can be located near the end (i.e., the second end) of the driving signal line to reduce the noise caused by the driving signal line being too long and the distance between adjacent driving signal lines being too small, and the process difficulty is relatively low; a binding area is provided on the substrate of the ultrasonic sensor, and the second end of the driving signal line can be electrically connected to the binding area, and then electrically connected to the pixel circuit in the ultrasonic sensor through the binding area.

[0052] Optionally, the multiple drive circuits on the driver circuit board 510 may include: a DC drive circuit and an AC drive circuit. The DC drive circuit can output a DC drive signal, and the AC drive circuit can output an AC drive signal (or a timing drive signal). The multiple drive signal lines on the flexible circuit board 520 may include: a DC drive signal line and an AC drive signal line. The first end of the DC drive signal line can be electrically connected to the DC drive circuit, the second end can be electrically connected to the ultrasonic sensor 530, and the third end can be electrically connected to the first noise reduction circuit. The first end of the AC drive signal line can be electrically connected to the AC drive circuit, the second end can be electrically connected to the ultrasonic sensor 530, and the third end can be electrically connected to the second noise reduction circuit.

[0053] The DC drive circuit may include: a DC power supply circuit and a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) drive circuit, and the AC drive circuit may include a MOSFET drive circuit and a gate drive circuit, wherein the MOSFET drive circuit can be used as both a DC drive circuit and an AC drive circuit.

[0054] Figure 6 A specific structure of an ultrasound imaging system is shown, referring to Figure 6 For example, the DC power supply circuit may include a DC power supply and a voltage stabilizing circuit that are electrically connected, wherein the DC power supply may be a DC (Direct Current) / DC power supply module ( Figure 6 Not shown), the voltage stabilizing circuit may be as follows Figure 6 The LDO (Low Dropout Regulator) shown in the figure has a DC power supply and voltage regulator circuit that provides a DC power supply signal Vdd. The MOSFET driver circuit provides a DC bias signal Vbias, as well as an AC reset signal Vrst and a control signal Vclose. The gate driver circuit (also known as a gate driver circuit) provides a gate drive signal Gate. The number of MOSFET driver circuits can be three, each of which can provide the bias signal Vbias, the reset signal Vrst, and the Vclose signal.

[0055] Reference Figure 6 In the example of , the multiple drive signal lines on the flexible circuit board 520 include drive signal lines corresponding to five drive signals, the drive signal line corresponding to the power signal Vdd is also referred to as the power signal line, the drive signal line corresponding to the bias signal Vbias is also referred to as the bias signal line, the drive signal line corresponding to the reset signal Vrst is also referred to as the reset signal line, the drive signal line corresponding to the control signal Vclose is also referred to as the control signal line, and the drive signal line corresponding to the gate drive signal Gate is also referred to as the gate drive signal line. The DC drive signal line in the embodiment of the present application may include the above-mentioned power signal line and bias signal line, and the AC drive signal line may include the above-mentioned reset signal line, control signal line and gate drive signal line.

[0056] Reference Figure 6 In the example of FIG5 , both the power signal line and the bias signal line can be electrically connected to the corresponding first noise reduction circuit 5211, so that the noise on each DC drive signal line can be filtered out by the first noise reduction circuit 5211. In other examples, either the power signal line or the bias signal line can be electrically connected to the first noise reduction circuit 5211, so that the noise on any DC drive signal line can be filtered out by the first noise reduction circuit 5211.

[0057] Reference Figure 6 In one example, both the control signal line and the gate drive signal line are electrically connected to the corresponding second noise reduction circuit 5212, so that the noise on each AC drive signal line can be filtered out by the second noise reduction circuit 5212. In other examples, the control signal line and the gate drive signal line are electrically connected to the second noise reduction circuit 5212, so that the noise on any one of the control signal line and the gate drive signal line can be filtered out by the second noise reduction circuit 5212.

[0058] The reset signal line does not need to be connected to a noise reduction circuit to avoid a large delay that affects the timing requirements of the acquired signal.

[0059] Figure 7 A circuit principle of a MOSFET drive circuit is shown, referring to Figure 7 The MOSFET drive circuit may include a high-speed MOSFET driver, a field-effect transistor circuit (e.g., a TC6320 field-effect transistor circuit), a diode circuit, and a resistor. The field-effect transistor driver may be an MD1213, the field-effect transistor circuit may be a TC6320, and the resistor may have a value of 1M (megaohm). By controlling the input timing signal, the MOSFET drive circuit can generate a high-frequency pulse signal as an AC drive signal, providing a strong load driving capability. Figure 7 Where VPP is a positive voltage and VNN is a negative voltage.

[0060] The ultrasonic sensor 530 in the embodiment of the present application may include multiple pixel circuits distributed in an array. The power supply signal Vdd, bias signal Vbias, reset signal Vrst and control signal Vclose provided by the driving circuit board can all be global signals. When input into the ultrasonic sensor 530, each pixel circuit can be driven at the same time. Accordingly, the driving signal line can be simultaneously connected to the input port of the driving signal of each pixel circuit to meet the global input requirements of the driving signal. Figure 8 shows an example of connecting the power signal line to each pixel circuit, Figure 9 An example is shown in which a control signal line is connected to each pixel circuit.

[0061] Optional, such as Figure 6 As shown, the gate drive circuit can be electrically connected to a plurality of gate drive signal lines, and each gate drive signal line can be electrically connected to a corresponding second noise reduction circuit 5212. The number of gate drive signal lines can be the same as the number of rows of pixel circuits in the ultrasonic sensor 530. Figure 6Taking 200 gate drive signal lines as an example, in actual applications, the gate drive signal lines can also be of other numbers. When each gate drive signal line is connected to a second noise reduction circuit 5212, the noise on each gate drive signal line can be filtered out separately by each second noise reduction circuit 5212, thereby filtering out the noise of each connected row of pixel circuits.

[0062] Reference Figure 6 For example, the number of flexible circuit boards 520 in the embodiment of the present application can be two, for example Figure 6 Driver_FPC and Gate_FPC in the circuit are arranged to facilitate routing. The power signal line, bias signal line, reset signal line and control signal line can be located on Driver_FPC, and the gate drive signal line can be located on Gate_FPC. The actual routing is as follows: Figure 10 In other examples, based on routing requirements, the number of flexible circuit boards 520 can be more than three.

[0063] Optionally, the first noise reduction circuit 5211 and the second noise reduction circuit 5212 may each include at least one decoupling capacitor, one end of the decoupling capacitor being electrically connected to the corresponding drive signal line and the other end being grounded. The decoupling capacitor and the wiring resistance of the connected drive signal line may form a circuit as shown in FIG. Figure 11 The low-pass filter shown, Figure 11 In the figure, C represents the decoupling capacitor, and R represents the wiring resistance of the driving signal line connected to the decoupling capacitor. The low-pass filter formed by the decoupling capacitor C and the wiring resistance R of the driving signal line can filter out noise in the frequency band above the cutoff frequency.

[0064] Optional, such as Figure 6 As shown, the first noise reduction circuit 5211 may include a first decoupling capacitor C1 and a second decoupling capacitor C2 connected in parallel, and the second noise reduction circuit 5212 may include a third decoupling capacitor C3.

[0065] In the first noise reduction circuit 5211, the capacitance value of the first decoupling capacitor C1 can be determined based on the first filtering frequency and the AC drive resistance, and the capacitance value of the second decoupling capacitor C2 can be determined based on the second filtering frequency and the DC drive resistance. The first filtering frequency is the cutoff frequency of the low-pass filter circuit formed by the first decoupling capacitor C1 and the DC drive circuit. The first filtering frequency can be determined based on the first frequency range to be filtered out, and the second filtering frequency can be determined based on the second frequency range to be filtered out. The DC drive resistance can be the sum of the output impedance of the drive circuit and the resistance of the corresponding drive signal line. For example, for the drive channel where the power signal Vdd is located, the DC drive circuit can be the sum of the output impedance of the voltage stabilizing circuit and the resistance of the power signal line.

[0066] In one example, the capacitance value of the first decoupling capacitor C1 (or the capacitance value of the second decoupling capacitor C2) can be calculated as follows:

[0067] f=1 / (2πRC) Expression (1)

[0068] In expression (1), f represents the first filtering frequency (or the second filtering frequency), R represents the DC driving resistor connected to the first decoupling capacitor, and C represents the capacitance value of the first decoupling capacitor C1 (or the capacitance value of the second decoupling capacitor C2). Among them, f can be determined based on the first frequency range (or the second frequency range) to be filtered out, and the first frequency range can be determined artificially; R can be extracted from the PCB by simulation software or tested, and the simulation software can be Cadence (a software company) software. When both f and R are known, the capacitance value C can be calculated. The capacitance value of the first decoupling capacitor C1 (the second decoupling capacitor) can be less than or equal to the calculated capacitance value.

[0069] In one example, the capacitance value of the first decoupling capacitor C1 can be greater than the capacitance value of the second decoupling capacitor C2. For example, the capacitance value of the first decoupling capacitor can be 10 μF (microfarad), which can be used to filter out low-frequency noise. The capacitance value of the second decoupling capacitor C2 can be 0.10 μF, which can be used to filter out high-frequency noise. Here, low-frequency noise is noise in a first frequency range, and high-frequency noise is noise in a second frequency range. The first frequency range can include the second frequency range, and the lowest frequency of the first frequency range can be lower than the lowest frequency of the second frequency range. The first decoupling capacitor C1 can also filter out high-frequency noise, but parasitic inductance is easily generated when filtering out high-frequency noise, reducing the filtering effect of high-frequency noise. The setting of the second decoupling capacitor C2 can make up for the deficiency of the first decoupling capacitor C1 in filtering out high-frequency noise.

[0070] In the second noise reduction circuit 5212, the capacitance value of the third decoupling capacitor C3 can be determined based on the third filtering frequency and the AC drive resistance. The third filtering frequency is the cutoff frequency of the low-pass filter circuit formed by the third decoupling capacitor C3 and the AC drive signal line. The third filtering frequency can be determined based on the rise time of the AC drive signal. For example, the third filtering frequency corresponding to the gate drive signal can be determined based on the rise time of the gate drive signal. The AC drive resistance can be the sum of the output impedance of the AC drive circuit and the resistance of the AC drive signal line. For example, for the drive channel where the gate drive signal is located, the AC drive resistance can be the sum of the output impedance of the gate drive circuit and the resistance of the gate drive signal line.

[0071] In an optional implementation, the capacitance value of the third decoupling capacitor C1 can be calculated as follows:

[0072] f=0.35 / RT=1 / (2πRC) Expression (2)

[0073] In expression (2), f represents the third filter frequency, RT represents the rise time of the AC drive signal (the rise time can also be expressed as Tr), T represents the AC drive resistor connected to the third decoupling capacitor C3, and C represents the capacitance value of the third decoupling capacitor C3. RT can be found in the technical specifications, and R can be extracted from the PCB using simulation software (such as Cadence software) or measured. When both RT and R are known, the capacitance value C can be calculated.

[0074] The following takes the calculation of the capacitance value of the first decoupling capacitor C1 corresponding to the control signal Vclose as an example to introduce the specific application of the above expression (2). In an example, if the rise time RT of the control signal Vclose is 1μs (microseconds) in the technical specifications, the output impedance of the MOSFET drive circuit corresponding to the control signal Vclose extracted by the simulation software is 100Ω (ohms), and the wiring resistance of the control signal line is 0.14Ω, then the AC drive resistance corresponding to the control signal Vclose is 100.14Ω. Substituting 1μs and 100.14Ω into the above expression (2), we can get:

[0075] f = 0.35 / (1×10e6) = 35 kHz

[0076] C = (1 × 10e6) / (0.7 × π × 100.14) ≈ 1.6 nF (nanofarad)

[0077] At this time, the capacitance value of the first decoupling capacitor C1 corresponding to the control signal Vclose may be less than or equal to 1.6 nF, for example, may be 1 nF.

[0078] Table 1 shows an example of capacitance values ​​of decoupling capacitors corresponding to different driving signals.

[0079]

[0080] Referring to expression (1) in Table 1, the DC drive signals Vdd and Vbias have no Tr / Tf (rise time / fall time) requirements. The capacitance value of the first decoupling capacitor can be calculated based on the above expression (1) according to the output impedance of the DC drive circuit (not shown in Table 1) and the wiring resistance of the DC signal line. The AC drive signals Vrst, Vclose, and Gate1-200 (representing the gate drive signals Gate of rows 1 to 200 in the input ultrasonic sensor) have Tr / Tf requirements. The capacitance value of the second decoupling capacitor can be calculated based on the above expression (2) according to the Tr / Tf requirements (Tr and Tf have the same value, so only Tr is considered), the output impedance of the AC drive circuit (not shown in Table 1), and the wiring resistance of the AC signal line. The control signal line is not connected to the decoupling capacitor, so the calculation of the capacitance value is not involved.

[0081] The ultrasonic sensor 530 in the embodiment of the present application may include a plurality of sensor units distributed in an array, each of which includes Figure 12 The structure of the transmitting and receiving component 531 and the pixel circuit 532 can be referred to Figure 3 Pixel circuit 532 includes a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4 and a capacitor C4.

[0082] In such Figure 12 In the pixel circuit 532 shown, the control terminal, first terminal, and second terminal of the first transistor T1 are electrically connected to the reset signal terminal, the bias signal terminal, and the first node P1, respectively. The control terminal, first terminal, and second terminal of the second transistor T2 are electrically connected to the control signal terminal, the first node P1, and the second node P2, respectively. The control terminal, first terminal, and second terminal of the third transistor T3 are electrically connected to the second node P2, the power signal terminal, and the third node P3, respectively. The control terminal, first terminal, and second terminal of the fourth transistor T4 are electrically connected to the gate signal terminal, the third node P3, and the output terminal Out, respectively. One end of the capacitor C4 is electrically connected to the second node P2, and the other end is grounded. The reset signal terminal can be used to receive a reset signal Vrst provided by the MOSFET driver circuit, the bias signal terminal can be used to receive a bias signal Vbias provided by the MOSFET driver circuit, the control signal terminal can be used to receive a control signal Vclose provided by the MOSFET driver circuit, the power signal terminal can be used to receive a power signal Vdd provided by the voltage regulator circuit, and the gate signal terminal can be used to receive a gate drive signal Gate provided by the gate driver circuit. The capacitor C4 can be a parasitic capacitor of the circuit or a separate capacitor.

[0083] Figure 13 A timing diagram of each driving signal is shown, referring to Figure 13When the power supply signal Vdd and the bias signal Vbias both remain high, and the reset signal Vrst and the control signal Vclose are both high, the first transistor T1 is turned on, and the bias signal Vbias can be input to the first node P1, raising the potential of the first node P1. The reset signal Vrst can change from a high level to a low level at the peak of the echo signal RX, causing the first transistor T1 to switch from on to off, and the bias signal Vbias is no longer input to the first node P1 by the first transistor T1. At this time, the control signal Vclose remains high, and the second transistor T2 remains on. The induced voltage obtained by the echo signal collected and converted by the transmitting and receiving component 531 can be input to the second node P2, charging the capacitor C4, causing it to store the induced voltage of the echo signal. When the control signal Vclose changes from a high level to a low level, it latches the voltage of the capacitor C4. Each row's gate drive signal Gate can sequentially control the fourth transistor T4 in the connected row of pixel circuits 532 to turn on at a high level, sequentially reading the echo signal. Figure 13 Gate1, Gate2 and Gate200 represent the gate driving signals connected to the pixel circuits in the 1st row, the 2nd row and the 200th row respectively.

[0084] The ultrasonic sensor 530 in the embodiment of the present application can be of small size or large size, and the number of the corresponding driving circuit board 510 and the flexible circuit board 520 can be one group or multiple groups. The specific size range corresponding to the small size and the large size can be determined according to the actual situation. Figure 6 The set of driving circuit boards 510 and flexible circuit boards 520 shown in the figure can provide driving signals to all pixel circuits in the ultrasonic sensor 530. For a large-sized ultrasonic sensor 530, the number of pixel circuits is usually large, which can reach the order of millions or tens of millions. The driving load capacity of the set of driving circuit boards 510 and flexible circuit boards 520 is limited and may not be able to drive the large-sized ultrasonic sensor 530. In this case, the following configuration can be used: Figure 14 The multiple groups of driving circuit boards 510 and flexible circuit boards 520 shown perform partitioned driving, that is, each group of driving circuit boards 510 and flexible circuit boards 520 can drive the pixel circuits of one partition in the ultrasonic sensor 530 .

[0085] For large-sized ultrasonic sensors 530, the use of multiple sets of driver circuit boards 510 and flexible circuit boards 520 for partitioned driving can shorten the routing length of the drive signal lines. However, due to the sharp increase in routing, the noise introduced by the drive signal lines is still very large. The introduced noise includes power ripple of the driver circuit, crosstalk between flexible circuit boards, crosstalk between each drive signal line on the flexible circuit board, and electromagnetic interference (EMC) in space. In addition, due to the problem of non-uniform process of ultrasonic sensors, different partitions may have different loads in resistance and capacitance, while the specifications of the driver circuits used are the same, which will cause impedance mismatch in some partitions, resulting in overshoot and ringing in the waveform of the drive signal, which is equivalent to introducing a large amount of noise. In this case, the noise reduction circuit set on the flexible circuit board can still effectively filter out the noise of the drive signal line. By adjusting the capacitance value of the decoupling capacitor in the noise reduction circuit, the load of different partitions can be flexibly matched, thereby improving signal quality.

[0086] Figure 15 Shows an application scenario of a large-scale integrated flexible ultrasonic sensor, referring to Figure 15 This type of ultrasonic sensor can be used in the medical field. Specifically, this type of ultrasonic sensor can be used to cover the surface of human tissue, such as the surface of large areas of human tissue such as the abdomen, arms, and thighs, to achieve high-precision, large-area, multi-dimensional real-time imaging.

[0087] The ultrasonic imaging system provided in the embodiments of the present application can also be applied to fields such as fingerprint recognition and space detection.

[0088] Based on the same inventive concept, embodiments of the present application also provide a signal noise reduction method that can be applied to any of the ultrasound imaging systems provided in embodiments of the present application. The signal noise reduction method includes: using a noise reduction circuit on a flexible circuit board to reduce the noise of a drive signal output by a driver circuit board.

[0089] The signal noise reduction method provided in the embodiment of the present application can improve the quality of the echo signal collected by the pixel circuit by reducing the noise of the driving signal, thereby improving the quality of ultrasonic imaging.

[0090] Optionally, the noise reduction circuit on the flexible circuit board is used to reduce the noise of the driving signal output by the driving circuit board, which may include: filtering out noise in a first frequency range of the DC driving signal output by the DC driving circuit on the driving circuit board through a first noise reduction circuit on the flexible circuit board; and filtering out noise in a third frequency range of the AC driving signal output by the AC driving circuit on the driving circuit board through a second noise reduction circuit on the flexible circuit board.

[0091] The first frequency range may include the second frequency range. The first frequency range may be set manually, and the second frequency range may be determined based on the above expression (2) according to the rise time of the corresponding AC drive signal.

[0092] In the case where the noise reduction circuit includes a decoupling capacitor and the wiring resistance of the driving signal line connected to the decoupling capacitor can form a Figure 11 The low-pass filter shown can reduce the noise of the driving signal on the connected driving signal line and filter out the noise in the driving signal.

[0093] When the first noise reduction circuit includes a first decoupling capacitor and a second decoupling capacitor having different capacitance values, low-frequency noise in the DC drive signal can be filtered out based on the decoupling capacitor with a larger capacitance value, and high-frequency noise in the DC drive signal can be filtered out based on the decoupling capacitor with a smaller capacitance value. When the second noise reduction circuit includes a third decoupling capacitor, high-frequency noise in the AC drive signal can be filtered out based on the third decoupling capacitor.

[0094] When multiple drive signal lines, such as a power signal line, a bias signal line, a control signal line, and a gate drive signal line, are provided on a flexible circuit board, for each drive signal line, noise on the drive signal line can be filtered out based on a decoupling capacitor connected to the drive signal line. The specific filtering principle can be referred to the previous introduction and will not be repeated here.

[0095] The signal noise reduction method provided in the embodiment of the present application can be applied to Figure 6 The ultrasonic imaging system with a single set of driving circuit boards and flexible circuit boards shown in FIG. 1 can also be applied to Figure 14 The ultrasonic imaging system shown is provided with multiple sets of driving circuit boards and flexible circuit boards.

[0096] The signal noise reduction method provided in the embodiments of this application can be applied in the medical field. By reducing the noise of the driving signal, the quality of the echo signal collected by the pixel circuit can be improved, thereby improving the quality of ultrasound imaging. High-quality ultrasound images can help more accurately diagnose the patient's condition. The signal noise reduction method provided in the embodiments of this application can also be applied in fields such as fingerprint recognition and space exploration.

[0097] In order to test the effectiveness of the ultrasound imaging system and signal noise reduction method provided in the embodiments of the present application in improving the quality of ultrasound imaging, the inventors of the present application conducted simulation tests on the noise reduction of DC drive signals and the noise reduction of AC drive signals respectively.

[0098] Figure 16 The equivalent circuit of the ultrasonic imaging system without decoupling capacitors in the noise reduction simulation test of the DC drive signal is shown. Figure 16In the figure, V1 is a DC power supply with an amplitude of 10V (volts), the output impedance R3 is 100Ω, AC1 is a simulated noise source with a frequency of 1KHz and an amplitude of 100mV (millivolts), R1 is the wiring resistance of the DC drive signal line, and the resistance value is 0.13Ω, and OUT is the end of the drive signal line, which serves as the test point for the simulation test.

[0099] Figure 17 Shown Figure 16 The curve of the voltage V(out) at the test point OUT changing with time is given by Figure 17 It can be seen that on the basis of the 10V DC voltage output by the DC power supply, there is an AC signal with an amplitude of about 100mV, which means that the noise in the DC drive signal is 100mV at this time.

[0100] Figure 18 The equivalent circuit of part of the ultrasonic imaging system with decoupling capacitors in the noise reduction simulation test of the DC drive signal is shown. Figure 18 In the figure, V1 is a DC power supply with an amplitude of 10V, and the output impedance R3 is 100Ω. AC1 is a simulated noise source with a frequency of 1KHz and an amplitude of 100mV. R1 is the routing resistance of the DC drive signal line with a resistance value of 0.13Ω. C1 is the first decoupling capacitor with a capacitance value of 10μF. C2 is the second decoupling capacitor with a capacitance value of 0.1μF. OUT is the end of the drive signal line, which serves as the test point for the simulation test.

[0101] Figure 19 Shown Figure 18 The curve of the voltage V(out) at the test point OUT changing with time is given by Figure 18 It can be seen that based on the 10V DC voltage output by the DC power supply, there is an AC signal with an amplitude of about 16mV, which means that the noise in the DC drive signal is 16mV at this time. Compared with the case without decoupling capacitors, the noise in the DC drive signal is greatly reduced.

[0102] Figure 20 The equivalent circuit of the ultrasonic imaging system without decoupling capacitors in the noise reduction simulation test of the AC drive signal is shown. Figure 20 In the figure, V1 is an AC power supply that can output a pulse signal with an amplitude of 10V. The output impedance R3 is 100Ω. AC1 is a simulated noise source with a frequency of 1KHz and an amplitude of 100mV. R1 is the wiring resistance of the AC drive signal line with a resistance value of 0.34Ω. OUT is the end of the drive signal line, which serves as the test point for the simulation test.

[0103] Figure 21 Shown Figure 20 The curve of the voltage V(out) at the test point OUT changing with time is given by Figure 21It can be seen that the rise time of V(out) is about 0.2μs, which meets the technical specification requirement of less than 1μs. After rising, it stabilizes at around 14.88V, indicating that the noise in the DC drive signal at this time is 100mV.

[0104] Figure 22 The equivalent circuit of part of the ultrasonic imaging system with decoupling capacitors in the noise reduction simulation test of the AC drive signal is shown. Figure 22 In the figure, V1 is an AC power supply that can output a pulse signal with an amplitude of 10V. The output impedance R3 is 100Ω. AC1 is a simulated noise source with a frequency of 1KHz and an amplitude of 100mV. R1 is the routing resistance of the AC drive signal line with a resistance value of 0.34Ω. C2 is a decoupling capacitor with a capacitance value of 1nF. OUT is the end of the drive signal line, which serves as the test point for the simulation test.

[0105] Figure 23 Shown Figure 22 The curve of the voltage V(out) at the test point OUT changing with time is given by Figure 22 It can be seen that the rise time of V(out) is about 0.5μs, meeting the technical specification requirement of less than 1μs. After rising, it stabilizes at around 14.65V, reducing the noise in the AC drive signal compared to the case without decoupling capacitors.

[0106] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless they are mutually inconsistent.

[0107] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0108] The word "comprising" used in this specification refers to the features, integers, steps, operations, elements and / or components stated, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. The word "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0109] The terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like in this specification indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to this application.

[0110] In this specification, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0111] Should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intermediate elements may exist. In addition, "connected" or "coupled" used herein may include wireless connection or wireless coupling.

[0112] In this specification, "electrically connected" includes components connected together via an element having some electrical function. There are no particular limitations on the "element having some electrical function" as long as it enables the transfer of electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other components with various functions.

[0113] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An ultrasonic imaging system, characterized in that: include: Driver circuit board, flexible circuit board and ultrasonic sensor; The driving circuit board is used to provide a driving signal to the ultrasonic sensor through the flexible circuit board; The flexible circuit board is provided with a noise reduction circuit, and the noise reduction circuit is used to filter out noise in the driving signal; the driving circuit board is provided with multiple driving circuits, and the flexible circuit board is provided with multiple driving signal lines; The multiple drive circuits include: a DC drive circuit, and the multiple drive signal lines include: a DC drive signal line; a first end of the DC drive signal line is electrically connected to the DC drive circuit, a second end is electrically connected to the ultrasonic sensor, and a third end is electrically connected to a first noise reduction circuit, and the other end of the first noise reduction circuit is grounded; the first noise reduction circuit includes a first decoupling capacitor and a second decoupling capacitor connected in parallel; in the first noise reduction circuit, the capacitance value of the first decoupling capacitor is determined according to a first filtering frequency and a DC drive resistor, and the capacitance value of the second decoupling capacitor is determined according to a second filtering frequency and a DC drive resistor; The first filtering frequency is determined based on a first frequency range to be filtered out; The second filtering frequency is determined based on a second frequency range to be filtered out; The DC drive resistance is the sum of the output impedance of the DC drive circuit and the resistance of the DC drive signal line.

2. The ultrasonic imaging system according to claim 1, wherein: The first end of the driving signal line is electrically connected to the corresponding driving circuit, and the second end is electrically connected to the ultrasonic sensor; The third end of at least one driving signal line is electrically connected to the corresponding noise reduction circuit; The distance between the second end and the third end of the driving signal line is within a preset distance range.

3. The ultrasonic imaging system according to claim 2, wherein: The plurality of driving circuits include: an AC driving circuit, and the plurality of driving signal lines include: an AC driving signal line; A first end of the AC drive signal line is electrically connected to the AC drive circuit, a second end is electrically connected to the ultrasonic sensor, and a third end is electrically connected to the second noise reduction circuit.

4. The ultrasonic imaging system according to claim 3, wherein: The AC drive circuit includes: a gate drive circuit; the AC drive signal line includes a gate drive signal line; The gate driving circuit is electrically connected to a plurality of gate driving signal lines, and each gate driving signal line is electrically connected to a corresponding second noise reduction circuit.

5. The ultrasonic imaging system according to claim 3 or 4, characterized in that: The first noise reduction circuit and the second noise reduction circuit each include at least one decoupling capacitor; One end of the decoupling capacitor is electrically connected to the corresponding driving signal line, and the other end is grounded.

6. The ultrasonic imaging system according to claim 5, wherein: The second noise reduction circuit includes a third decoupling capacitor.

7. The ultrasonic imaging system according to claim 6, wherein: In the second noise reduction circuit, the capacitance value of the third decoupling capacitor is determined according to the third filtering frequency and the AC drive resistance; The third filtering frequency is determined based on the rise time of the AC driving signal; The AC driving resistance is the sum of the output impedance of the AC driving circuit and the resistance of the AC driving signal line.

8. A signal noise reduction method, characterized in that: Applied to the ultrasound imaging system according to any one of claims 1 to 7, the signal noise reduction method comprises: The noise reduction circuit on the flexible circuit board is used to reduce the noise of the driving signal output by the driving circuit board.

9. The signal noise reduction method according to claim 8, characterized in that: The noise reduction circuit on the flexible circuit board is used to reduce the noise of the driving signal output by the driving circuit board, including: filtering out noise in a first frequency range of a DC drive signal output by a DC drive circuit on the drive circuit board through a first noise reduction circuit on the flexible circuit board; The second noise reduction circuit on the flexible circuit board is used to filter out noise within a third frequency range of the AC driving signal output by the AC driving circuit on the driving circuit board.

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