Differential line impedance adjusting method and display panel

Abstract

The invention relates to an impedance adjusting method of a differential line and a display panel. The impedance adjustment method of the differential line comprises the following steps: acquiring eye pattern data of the differential line between a driving circuit and a flexible circuit board in the display panel; determining the target impedance of the differential line according to the eye pattern data; according to the target impedance, the target resistance value of an adjustable resistor connected with the differential line in parallel and the target capacitance value of an adjustable capacitor connected with the differential line in parallel are determined, and the impedance of the differential line under the target resistance value and the target capacitance value is the target impedance; the resistance value of the adjustable resistor is adjusted to be the target resistance value, and the capacitance value of the adjustable capacitor is adjusted to be the target capacitance value. According to the invention, the technical problem of poor data transmission quality caused by impedance of the differential line is solved.

Description

Technical Field

[0001] This application relates to the field of liquid crystal displays, and more particularly to a method for adjusting the impedance of differential lines and a display panel. Background Technology

[0002] LCD displays have become the mainstream display technology due to their advantages such as being thin, light, and having low power consumption.

[0003] In existing liquid crystal displays, the differential lines exhibit differential impedance during data transmission. Differential impedance is the impedance experienced by the differential signal during transmission. If the differential impedance is stable at a suitable fixed value, the transmission quality of the differential signal is high. However, in reality, due to various factors, the differential impedance is not stable, resulting in poor differential signal transmission quality. Summary of the Invention

[0004] This application provides an impedance adjustment method for differential lines and a display panel to solve the technical problem of poor data transmission quality caused by unstable impedance of differential lines.

[0005] In a first aspect, this application provides a method for adjusting the impedance of a differential line, comprising: acquiring eye diagram data of a differential line between a driving circuit and a flexible circuit board in a display panel; determining a target impedance of the differential line based on the eye diagram data; determining a target resistance value of an adjustable resistor connected in parallel with the differential line and a target capacitance value of an adjustable capacitor connected in parallel with the differential line based on the target impedance, wherein the impedance of the differential line at the target resistance value and the target capacitance value is the target impedance; adjusting the resistance value of the adjustable resistor to the target resistance value, and adjusting the capacitance value of the adjustable capacitor to the target capacitance value.

[0006] For example, determining the target impedance of the differential line based on the eye diagram data includes: obtaining the current impedance of the differential line; comparing the eye diagram data with standard eye diagram data; and when the eye diagram data does not match the standard eye diagram data, increasing or decreasing the impedance value based on the current impedance according to the degree of mismatch to obtain the target impedance.

[0007] For example, determining the target resistance value of the adjustable resistor connected in parallel with the differential line and the target capacitance value of the adjustable capacitor connected in parallel with the differential line based on the target impedance includes determining the target resistance value and the target capacitance value according to the following formulas:

[0008] Where R is the resistance value, ranging from [50, 150Ω], C is the capacitance value, ranging from [0.1, 5pF], L is the parasitic inductance, with a value of 3nH, Zdiff(R,C) is the target impedance mentioned above, j is the imaginary unit, and f is the signal frequency.

[0009] For example, the method further includes: determining the thickness and dielectric constant of different layers of dielectric material around the differential lines on the display panel based on the differential impedance of the differential lines, so as to make the differential impedance of the differential lines transition smoothly.

[0010] For example, the method further includes: determining the linewidth of the positive line and the linewidth of the negative line of the differential line based on the differential impedance of the differential line, so that the differential impedance of the differential line is equal to the target impedance.

[0011] For example, the above method further includes: obtaining accurate eye diagram data by adjusting the spacing between the near end and far end of the differential line and the positive and negative lines in the middle portion excluding the near end and far end, wherein the near end is the end close to the driving circuit and the far end is the end close to the flexible circuit board.

[0012] Secondly, this application provides a display panel, including: a driving circuit; a flexible circuit board; a differential line connecting the driving circuit and the flexible circuit board; an adjustable resistor connected in parallel with the differential line; and an adjustable capacitor connected in parallel with the differential line; wherein the target resistance value of the adjustable resistor and the target capacitance value of the adjustable capacitor are determined based on the target impedance of the differential line, and the target impedance is determined based on the eye diagram data of the differential line.

[0013] For example, the differential lines are located in the differential line layer of the display panel, and the display panel further includes: a near-field layer located on the first side of the differential line layer; a transition layer located on the first side of the near-field layer; and a far-field layer located on one side of the transition layer; wherein the dielectric constant of the near-field layer is greater than or equal to the dielectric constant of the transition layer, and the dielectric constant of the transition layer is greater than or equal to the dielectric constant of the far-field layer.

[0014] For example, the differential line mentioned above includes a first sub-differential line and a second sub-differential line, wherein the line width of the first sub-differential line is greater than the line width of the second sub-differential line.

[0015] For example, the differential line includes a first sub-differential line and a second sub-differential line. The line spacing between the first sub-differential line and the second sub-differential line on the side connected to the driving circuit is twice the line width. The line spacing between the first sub-differential line and the second sub-differential line on the side connected to the flexible circuit board is twice the line width. The line spacing between the first sub-differential line and the second sub-differential line on both sides is less than a preset spacing.

[0016] Compared with the prior art, the technical solution provided in this application has the following advantages: This application obtains eye diagram data of the differential line between the driving circuit and the flexible circuit board in the display panel; determines the target impedance of the differential line based on the eye diagram data; determines the target resistance value of the adjustable resistor connected in parallel with the differential line and the target capacitance value of the adjustable capacitor connected in parallel with the differential line based on the target impedance, wherein the impedance of the differential line under the target resistance value and the target capacitance value is the target impedance; adjusts the resistance value of the adjustable resistor to the target resistance value and adjusts the capacitance value of the adjustable capacitor to the target capacitance value, thereby determining the target impedance based on the eye diagram data of the differential line, and determining the matching target resistance value and target capacitance value based on the target impedance. By adjusting the resistance and capacitance values ​​of the adjustable resistor and the adjustable capacitor, the impedance of the differential line is maintained at a stable target impedance, thereby improving the transmission quality of the differential signal. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 A flowchart illustrating an impedance adjustment method for a differential line provided in this application embodiment; Figure 2 A control flowchart provided for an embodiment of this application; Figure 3 Another control flowchart provided for embodiments of this application; Figure 4 This is a schematic diagram of a differential line provided in an embodiment of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0023] To address the poor data transmission quality caused by unstable impedance of differential lines in existing technologies, this application provides a method for adjusting the impedance of differential lines, such as... Figure 1 As shown, it includes: S102, Obtain eye diagram data of the differential line between the driving circuit and the flexible circuit board in the display panel; S104, Determine the target impedance of the differential line based on the eye diagram data; S106, Based on the target impedance, determine the target resistance value of the adjustable resistor connected in parallel with the differential line and the target capacitance value of the adjustable capacitor connected in parallel with the differential line, wherein the impedance of the differential line under the target resistance value and the target capacitance value is the target impedance. S108, adjust the resistance value of the adjustable resistor to the target resistance value, and adjust the capacitance value of the adjustable capacitor to the target capacitance value.

[0024] The method in this application can be applied to display screens as display panels. The display panel includes a driver chip, which is directly bonded to a flexible printed circuit (FPC) or rigid circuit board via a chip-on-film (COF) film to achieve connection with the display panel. The COF acts as a bridge between the driver chip and the flexible circuit board, transmitting differential signals to the flexible circuit board through differential lines between the driver chip and the flexible circuit board to control the image displayed on the display panel.

[0025] The data from the driver chip is transmitted to the flexible circuit board via differential lines in the differential line layer. The flexible circuit board converts the differential signal into a data signal, which is then transmitted to the data signal line (LCD dataline) in the wiring layer.

[0026] During the transmission of differential signals via differential lines, the differential signals will experience differential impedance. Maintaining the differential impedance at a suitable value can improve the transmission quality of the differential signals.

[0027] In this example, to improve the transmission quality of the differential signal, an adjustable resistor and an adjustable capacitor can be connected in parallel on the differential lines of the differential line layer. The adjustable resistor is a digital potentiometer with an adjustable resistance value, and the adjustable capacitor is a capacitor array with an adjustable capacitance value. By adjusting the resistance and capacitance values ​​of the adjustable resistor and the adjustable capacitor, the differential impedance of the differential line can be kept at a stable and appropriate value.

[0028] The resistance value of the digital potentiometer and the capacitance value of the capacitor array can be adjusted under the control of the control chip. The control chip can determine the appropriate value of the differential impedance of the differential line. For example, if the target impedance of the differential impedance is determined to be 100 ohms, the differential impedance of the differential line can be maintained at 100 ohms by adjusting the resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor.

[0029] In addition, the target impedance of the differential impedance can also be a range, such as 95-105 ohms. Then, by adjusting the resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor, the differential impedance of the differential line can be kept at 95-105 ohms.

[0030] To determine the appropriate target impedance, this example uses the eye diagram data of the differential lines to determine the target impedance.

[0031] The principle of determining the target impedance based on eye diagram data is as follows: By observing the eye diagram data of the differential lines, anomalies are identified. If there are abnormalities in the eye width, eye height, or other data, it indicates that the current differential impedance of the differential lines is inappropriate. Based on the type of anomaly in the eye diagram data, a suitable value for the differential impedance is determined, and this value is set as the target impedance. By adjusting the resistance and capacitance values ​​of the adjustable resistor and capacitor, the impedance of the differential lines is brought to the target impedance, thus restoring the output eye diagram data to normal.

[0032] If it is desired that the differential impedance of the differential line is stabilized at the target impedance, the resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor need to be determined. By using the correspondence between the target impedance and the resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor, the accurate target resistance and target capacitance values ​​can be determined. The resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor can then be controlled to achieve the differential impedance of the differential line being the target impedance.

[0033] This application obtains eye diagram data of the differential lines between the driving circuit and the flexible circuit board in the display panel; determines the target impedance of the differential lines based on the eye diagram data; determines the target resistance value of the adjustable resistor connected in parallel with the differential lines and the target capacitance value of the adjustable capacitor connected in parallel with the differential lines based on the target impedance, wherein the impedance of the differential lines under the target resistance value and the target capacitance value is the target impedance; adjusts the resistance value of the adjustable resistor and the capacitance value of the adjustable capacitor to the target resistance value, thereby determining the target impedance based on the eye diagram data of the differential lines, and determining the matching target resistance value and target capacitance value based on the target impedance. By adjusting the resistance and capacitance values ​​of the adjustable resistor and the adjustable capacitor, the impedance of the differential lines is maintained at a stable target impedance, improving the transmission quality of the differential signal.

[0034] For example, determining the target impedance of a differential line based on eye diagram data includes: obtaining the current impedance of the differential line; comparing the eye diagram data with standard eye diagram data; and, if the eye diagram data does not match the standard eye diagram data, increasing or decreasing the impedance value based on the degree of mismatch to obtain the target impedance.

[0035] In this example, after obtaining the eye diagram data of the differential line, the eye diagram data can be compared with the standard eye diagram in terms of at least one of the following: eye height, eye width, time interval error of eye jitter, random value of eye jitter, rise / fall time, and overshoot rate. If the comparison result shows a mismatch between the eye diagram data and the standard eye diagram, an anomaly in the eye diagram data is identified. In this case, the target impedance is determined by the difference between the compared eye diagram data and the standard eye diagram data. For example, if the comparison reveals a difference in eye height, with the eye height of the eye diagram data being smaller than that of the standard eye diagram data, this indicates that the differential impedance is too small. Therefore, the impedance value is increased based on the current differential impedance to obtain the target impedance. Conversely, if the eye width of the eye diagram data is larger than that of the standard eye diagram data, this indicates that the differential impedance is too large. The impedance value is decreased based on the current differential impedance to obtain the target impedance.

[0036] It should be noted that the above examples are only to illustrate the relationship between eye diagram data and target impedance. The difference between the eye diagram data and standard eye diagram data can be preset, along with the corresponding impedance adjustment method. Therefore, after comparing the eye diagram data with the standard eye diagram data, the difference between the two can be used to determine how to adjust the current impedance to obtain the target impedance.

[0037] In this example, by adjusting the resistance value of the digital potentiometer and the capacitance value of the capacitor array, the differential impedance of the differential line is kept at the target impedance, thereby improving the transmission quality of the differential signal.

[0038] For example, determining the target resistance value of the adjustable resistor connected in parallel with the differential line and the target capacitance value of the adjustable capacitor connected in parallel with the differential line, based on the target impedance, includes determining the target resistance value and the target capacitance value according to the following formulas: (1) Where R is the resistance value, ranging from [50, 150Ω], C is the capacitance value, ranging from [0.1, 5pF], L is the parasitic inductance, with a value of 3nH, and Z... diff (R,C) represents the target impedance, j is the imaginary unit, and f is the signal frequency.

[0039] This example provides formulas for determining the target resistance and target capacitance values ​​of the adjustable resistor and adjustable capacitor based on the target impedance. In the above formulas, Z... diff The target impedance is C, the target capacitance, and the target resistance is R, which are unknown. The impedance is calculated by varying R and C within a certain range until at least one set of R and C values ​​is found, corresponding to the target impedance. This set of resistance and capacitance values ​​then represents the target resistance and target capacitance values.

[0040] If multiple sets of target resistance and target capacitance values ​​are calculated, adjust the resistance and capacitance values ​​of the adjustable resistor and adjustable capacitor using any one of these sets.

[0041] For example, the above method further includes: determining the thickness and dielectric constant of different layers of dielectric material around the differential lines on the display panel based on the differential impedance of the differential lines, so as to make the differential impedance of the differential lines transition smoothly.

[0042] In this example, the differential lines are distributed in a differential line layer. The dielectric material surrounding the differential line layer, with its varying thickness and dielectric constant, affects the differential impedance of the differential lines. To ensure stable differential impedance, a dielectric layer can be placed between the differential line layer and the data line layer. This dielectric layer consists of multiple sub-dielectric layers. The dielectric constant of the sub-dielectric layers closer to the differential line layer is higher, gradually decreasing as they approach the data line routing layer, until the dielectric constant of the sub-dielectric layer in contact with the routing layer is the same as that of the routing layer. This achieves a uniform structure where the dielectric constant of the dielectric layer gradually decreases from the differential line layer to the routing layer.

[0043] To achieve a gradual decrease in the dielectric constant of the dielectric layer, several methods can be employed. One method involves using multiple dielectric materials with different dielectric constants to form sub-dielectric layers, which together constitute the dielectric layer. The closer the dielectric constant of the sub-dielectric layers is to the trace layer, the lower its dielectric constant.

[0044] In this approach, a material with the same dielectric constant as the trace layer needs to be found as the layer in the dielectric layer that contacts the trace layer, ensuring that the dielectric constant of the region where the dielectric layer contacts the trace layer remains unchanged. If it is not possible to guarantee that the dielectric constant of the layer in contact with the trace layer is the same as that of the trace layer, then the dielectric constant of the layer in contact with the trace layer should be slightly greater than that of the trace layer.

[0045] Another approach involves mixing materials with different dielectric constants to change their proportions, thus obtaining dielectric layers with varying dielectric constants. For example, a material with a low dielectric constant and a material with a high dielectric constant can be selected. The material with the high dielectric constant is gradually added to the material with the low dielectric constant, changing the proportion of the material with the high dielectric constant, thereby obtaining a dielectric layer with increasingly higher dielectric constants. In this approach, after adding the material with the high dielectric constant to the material with the low dielectric constant, the proportion can be controlled to obtain a material with the same dielectric constant as the trace layer. This material is then cured to form the contact area between the dielectric layer and the trace layer. The proportion of the material with the high dielectric constant is then gradually increased towards the direction away from the trace layer, and the material is gradually cured to obtain a dielectric layer with increasingly higher dielectric constants, where the dielectric constant of the contact area between the dielectric layer and the trace layer is the same as that of the trace layer.

[0046] For example, the dielectric layer may include a near-field layer, a transition layer, and a far-field layer. The near-field layer has a larger dielectric constant, the far-field layer has the same dielectric constant as the trace layer, and the transition layer has a dielectric constant that transitions from the near-field layer to the trace layer.

[0047] Therefore, when the differential signal passes through the trace, its dielectric constant has already decreased to match that of the trace layer before entering it. Thus, the dielectric constant remains unchanged when the signal enters the trace layer, ensuring smooth signal transmission. The dielectric constant of the transition layer increases from the trace layer to the near-field layer, allowing the dielectric constant to decrease slowly as the signal propagates from the near-field layer to the far-field layer, preventing abrupt changes in dielectric constant that could cause signal reflection. This ensures the stability of the differential impedance of the differential lines.

[0048] The differential impedance is calculated using the following formula, which determines that the differential impedance changes smoothly due to the uniform change in dielectric constant when the differential line passes through layers.

[0049] (2) In this example, the dielectric layer can use polyimide as the base dielectric, doped with nano-alumina. The volume fraction of nano-alumina in different gradient levels of the dielectric layer gradually increases from 5% to 25%, forming different gradient levels of dielectric constants. Polyimide has a relatively low dielectric constant, lower than that of the wiring layer. Doping polyimide with nano-alumina gradually increases the dielectric constant of the dielectric layer as the volume fraction of nano-alumina increases. In this example, the dielectric layer starts with 5% nano-alumina doping. Doping with 5% nano-alumina raises the dielectric constant of the dielectric layer to the same level as the wiring layer. Therefore, the volume fraction of nano-alumina in the polyimide near the wiring layer is controlled at 5%. Then, as the dielectric moves away from the wiring layer, the volume fraction of nano-alumina is gradually increased. When it reaches 25%, the dielectric constant of the dielectric layer increases, forming a dielectric layer with a gradually decreasing dielectric constant from the near-field layer to the wiring layer.

[0050] For example, the above method further includes: determining the linewidth of the positive line and the linewidth of the negative line of the differential line based on the differential impedance of the differential line, so that the differential impedance of the differential line is equal to the target impedance.

[0051] Besides setting the dielectric constant, the linewidth of the differential lines in the differential layer can also be adjusted to stabilize the differential impedance. A differential line in a differential layer consists of two lines: one positive and one negative, with the original linewidths being the same. However, in this example, the linewidths of the positive and negative lines are set to be different. The purpose of setting the linewidths differently is to compensate for impedance imbalances caused by environmental changes.

[0052] When line widths are inconsistent, the positive line width can be set to be greater than the negative line width. This can be achieved by increasing the positive line width, decreasing the negative line width, or both. Increasing the positive line width reduces its single-ended impedance, while decreasing the negative line width increases it. By increasing the positive line width and decreasing the negative line width, the single-ended impedance is adjusted, further balancing the differential impedance and compensating for impedance imbalances caused by environmental changes.

[0053] The line width of the positive line can be increased by 3%-8%, and the line width of the negative line can be decreased by 3%-8%. Typically, every 1% change in line width can cause a 0.6 ohm change in single-ended impedance.

[0054] For example, the above method further includes: obtaining accurate eye diagram data by adjusting the spacing between the near end and far end of the differential line and the positive and negative lines in the middle portion excluding the near end and far end, wherein the near end is the end closer to the driving circuit and the far end is the end closer to the flexible circuit board.

[0055] In this example, in addition to adjusting the linewidth of the differential lines in the differential line layer, the spacing between the positive and negative lines was also adjusted. Adjusting the spacing of the differential lines ensures the accuracy of the eye diagram data, further guaranteeing the accuracy of the determined target impedance. In this example, the side of the positive and negative lines closest to the output terminal of the driver chip is defined as the near end, and the spacing of the lines at the near end is adjusted to a larger pitch. The side closest to the flexible circuit board is defined as the far end, and the spacing of the lines at the far end is also adjusted to a larger pitch. The spacing of the lines in the middle of both ends is kept unchanged or reduced. Increasing the spacing can be achieved by adjusting the spacing to twice the linewidth.

[0056] The method in this embodiment adjusts the spacing between the positive and negative lines at different positions in the differential line, enabling the use of large spacing at the far and near ends to reduce crosstalk, and the use of small spacing in the middle part of the line to improve the coupling coefficient and suppress common-mode noise.

[0057] The following example illustrates this. To improve the quality of differential signals transmitted through differential lines, a dielectric layer is placed between the differential line layer and the trace layer in this example. This is achieved by precisely controlling the dielectric constant of the dielectric material surrounding the positive and negative transmission lines of the differential lines. This allows the dielectric constant to form a three-dimensional gradient distribution, achieving a continuous impedance transition and solving the signal reflection problem caused by the abrupt change in dielectric constant due to differential lines crossing layers.

[0058] The specific design involves setting three gradient transition regions on both sides of the difference line; these three gradient transition regions are the dielectric layers. These include: Near-field layer: =4.2 (High dielectric region, used to suppress edge field leakage) Transition layer: =4.2→3.5 gradual change (according to the function) The dielectric constant ε(x) is a function of position x in the transition layer, where x refers to the distance from the near-field layer. Far-field layer =3.5 (matching the substrate of the wiring layer).

[0059] To fabricate the dielectric layer, polyimide (PI) was chosen as the base material, which has an inherent dielectric constant. 3.2, Simultaneously doped with nano-alumina (Al2O3), its dielectric constant 9.8, by changing the volume fraction of the dopant alumina This achieves continuously adjustable dielectric constant. The formula is: (3) Where, ε eff The dielectric layer varies with the volume fraction of alumina. The dielectric constant changes with the volume fraction. Each 1% change in volume fraction corresponds to Δ... The dielectric constant is approximately 0.06 ohms, with a doping volume fraction ranging from 5% to 25%. To form a dielectric layer with a uniformly varying dielectric constant, a continuous variation can be achieved through the gradient distribution of nanoparticles, resulting in a smooth transition of characteristic impedance and a reduced impedance abrupt change rate during layer crossing.

[0060] Furthermore, not only are dielectric layers with uniformly varying dielectric constants set in the differential line layer and the trace layer, but the linewidths of the positive and negative signal lines of the differential lines are also adjusted. This is achieved by actively introducing the linewidth difference between the positive and negative lines of the differential pair. (in For positive line width, (for negative linewidth), to compensate for manufacturing tolerance linewidth ±10% and impedance imbalance caused by environmental changes.

[0061] positive line width = The single-ended impedance is reduced by increasing the line width; negative line width. = The single-ended impedance is increased by reducing the line width. The adjustment range is generally 3%-8% of the design standard line width, and each 1% change in line width causes an impedance change of approximately 0.6Ω.

[0062] When the standard value of line width =0.1mm, when manufacturing tolerances cause a positive line width of ±10%, set: = +5% =0.105mm, = -5% =0.095mm, which can narrow the impedance deviation from ±8Ω to ±2Ω.

[0063] After adjusting the line width, the differential impedance is calculated using the following formula. Where Z0 is the single-sided impedance, Z... diff denoted by , where w is the differential impedance of the differential line, t is the line width, h is the line thickness, and s is the dielectric layer thickness. The dielectric constant of the dielectric layer is: (4) (5) In addition to adjusting the line width, the distance between the positive and negative signal lines of the differential lines can also be adjusted.

[0064] The differential line is taken as the near end of the driver chip output terminal, and the near end crosstalk coefficient NEXT is defined. (6) Local self-sensing , The original spacing is adjusted by the near-end crosstalk coefficient to obtain the near-end spacing. The near-end spacing being greater than twice the line width W can effectively reduce near-end crosstalk.

[0065] The side of the differential line closest to the flexible circuit board is defined as the far end, and the far-end crosstalk coefficient FEXT is defined. (7) Where: K is the coupling coefficient, L is the parallel trace length, and f is the signal frequency. For the speed of transmission.

[0066] Adjusting the initial spacing by controlling the far-end crosstalk coefficient, and increasing the spacing at the output end helps reduce the coupling coefficient k. The far-end spacing is also twice the linewidth, which can effectively suppress far-end crosstalk and reduce the bit error rate. For example, ... Figure 2 As shown, the spacing between the proximal and distal ends is wider, while the spacing in the middle part is narrower.

[0067] The section between the input and output terminals uses a narrow pitch design.

[0068] Define the coupling coefficient (K): K= (8) s is the line spacing, h is the dielectric thickness. is the dielectric constant. Reducing the line spacing helps improve the coupling coefficient; strong coupling allows the electromagnetic field to concentrate between the differential pairs, suppressing common-mode noise.

[0069] In addition to adding a dielectric layer and adjusting the line width and line spacing as mentioned above, the differential impedance of the differential lines can also be adjusted by connecting a digital potentiometer and a capacitor array in parallel with the differential lines.

[0070] Figure 3 This is a schematic diagram illustrating how the control chip in this example controls the resistance value of the digital potentiometer and the capacitance of the adjustable capacitor array. (See diagram for example.) Figure 3 As shown, the data monitoring and processing module sends the resistance and capacitance values ​​determined based on the eye diagram data to the control chip. The control chip then controls the resistance and capacitance values ​​of the digital potentiometer and the adjustable capacitor array based on these values. Figure 4 As shown, the digital detection processing module obtains eye diagram data, impedance parameters and feature parameters fed back by the multi-source detection module and the parameter feature extraction module through its data processing engine, calculates the target impedance, and calculates the target resistance value and target capacitance value according to the above formula (1), and sends them to the control chip.

[0071] The data processing engine can detect eye diagrams and impedance data, and feed them back to the feature extraction module. The feature extraction module performs feature extraction on the data to obtain the eye height of the eye diagram. Eye Width: Horizontal opening width (unit UI), representing the time interval error of eye diagram jitter. Random jitter extracted via a dual Dirac model, and the rise / fall time and overshoot rate of the jitter in the eye diagram were obtained: 20%-80% level time: *100% and differential impedance. By calculating and processing the characteristic data, and setting characteristic parameters and constraining differential impedance conditions according to the COF eye diagram specifications, the target impedance is obtained. The target impedance can be a range, such as 95Ω ≤ ≤105Ω, the result is calculated using the resistor-capacitor and differential impedance model, i.e., the above formula (1).

[0072] This application embodiment also provides a display panel, including: a driving circuit; a flexible circuit board; a differential line connecting the driving circuit and the flexible circuit board; an adjustable resistor connected in parallel with the differential line; and an adjustable capacitor connected in parallel with the differential line; wherein the target resistance value of the adjustable resistor and the target capacitance value of the adjustable capacitor are determined according to the target impedance of the differential line, and the target impedance is determined according to the eye diagram data of the differential line.

[0073] For example, the differential lines are located in the differential line layer of the display panel, and the display panel further includes: a near-field layer located on the first side of the differential line layer; a transition layer located on the first side of the near-field layer; and a far-field layer located on one side of the transition layer; wherein the dielectric constant of the near-field layer is greater than or equal to the dielectric constant of the transition layer, and the dielectric constant of the transition layer is greater than or equal to the dielectric constant of the far-field layer.

[0074] For example, the differential line includes a first sub-differential line and a second sub-differential line, wherein the line width of the first sub-differential line is greater than the line width of the second sub-differential line.

[0075] For example, the differential line includes a first sub-differential line and a second sub-differential line. The line spacing between the first sub-differential line and the second sub-differential line on the side connected to the driving circuit is twice the line width. The line spacing between the first sub-differential line and the second sub-differential line on the side connected to the flexible circuit board is twice the line width. The line spacing between the first sub-differential line and the second sub-differential line on both sides is less than a preset spacing.

[0076] For other examples of this embodiment, please refer to the examples above, which will not be repeated here.

[0077] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0078] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0079] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0080] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method of adjusting the impedance of a differential line, characterized in that, The method comprises: acquiring eye diagram data of a differential line between a driving circuit and a flexible circuit board in a display panel; determining a target impedance of the differential line according to the eye diagram data; determining a target resistance value of an adjustable resistance in parallel with the differential line and a target capacitance value of an adjustable capacitance in parallel with the differential line according to the target impedance, wherein the impedance of the differential line under the target resistance value and the target capacitance value is the target impedance; adjusting the resistance value of the adjustable resistance to the target resistance value and adjusting the capacitance value of the adjustable capacitance to the target capacitance value.

2. The method of claim 1, wherein, The determining of the target impedance of the differential line according to the eye diagram data comprises: acquiring a current impedance of the differential line; comparing the eye diagram data with standard eye diagram data; when the eye diagram data does not match the standard eye diagram data, increasing or decreasing the impedance value on the basis of the current impedance according to the degree of the mismatch to obtain the target impedance.

3. The method of claim 1, wherein, The determining of the target resistance value of the adjustable resistance in parallel with the differential line and the target capacitance value of the adjustable capacitance in parallel with the differential line according to the target impedance comprises: determining the target resistance value and the target capacitance value according to the following formula: Wherein, R is the resistance value, ranging from [50, 150Ω], C is the capacitance value, ranging from [0.1, 5pF], L is the parasitic inductance, the value is 3nH, Z diff (R,C) is the target impedance, j is the imaginary unit, and f is the signal frequency.

4. The method of claim 1, wherein, The method further comprises: determining the thickness and the dielectric constant of different layers of dielectric material around the differential line on the display panel according to the differential impedance of the differential line, so as to smoothly transition the differential impedance of the differential line.

5. The method of claim 1, wherein, The method further comprises: determining the line width of the positive line and the line width of the negative line of the differential line according to the differential impedance of the differential line, so as to make the differential impedance of the differential line equal to the target impedance.

6. The method of claim 1, wherein, The method further comprises: obtaining accurate eye diagram data by adjusting the distance between the near end, the far end and the intermediate part of the positive line and the negative line of the differential line other than the near end and the far end, wherein the near end is the end close to the driving circuit and the far end is the end close to the flexible circuit board.

7. A display panel, characterized by, The display panel comprises: a driving circuit; a flexible circuit board; a differential line connecting the driving circuit and the flexible circuit board; an adjustable resistance in parallel with the differential line; and an adjustable capacitance in parallel with the differential line; wherein the target resistance value of the adjustable resistance and the target capacitance value of the adjustable capacitance are determined according to the target impedance of the differential line, and the target impedance is determined according to the eye diagram data of the differential line.

8. The display panel of claim 7, wherein, The differential line is located in a differential line layer of the display panel, and the display panel further comprises: a near field layer located on the first side of the differential line layer; a transition layer located on the first side of the near field layer; a far field layer located on the side of the transition layer; wherein the dielectric constant of the near field layer is greater than or equal to the dielectric constant of the transition layer, and the dielectric constant of the transition layer is greater than or equal to the dielectric constant of the far field layer.

9. The display panel of claim 7, wherein, The differential line comprises a first sub-differential line and a second sub-differential line, and the line width of the first sub-differential line is greater than the line width of the second sub-differential line.

10. The display panel of claim 7, wherein, The differential line includes a first sub-differential line and a second sub-differential line, the first sub-differential line and the second sub-differential line have a line spacing of twice the line width on the side connected to the driving circuit; the first sub-differential line and the second sub-differential line have a line spacing of twice the line width on the side connected to the flexible circuit board, and the first sub-differential line and the second sub-differential line have a line spacing less than a preset spacing between the two sides.

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