A brightness calibration repair method and system of a display panel

Abstract

This invention belongs to the field of display panel brightness calibration technology, and relates to a method and system for brightness calibration and repair of display panels. The method includes: acquiring the time-series accumulated amount of driving current for each pixel and the time-series accumulated amount of temperature derived from thermal conduction from neighboring pixels, as two types of degradation characterization components; using the current brightness deviation value as the reconstruction target and the degradation characterization components as decomposition factors, retrospectively decomposing the independent contributions of electrical stress and thermal stress to brightness decay; using the ratio of the two contributions as addressing parameters, matching the corresponding gain slope factor and intercept offset factor, and substituting them into the current grayscale to generate the initial compensation amount; then performing frame-by-frame iterative smooth convergence with the goal of minimizing the spatial gradient of the compensation amount between adjacent pixels, outputting the final compensation amount matrix to drive brightness calibration. This invention distinguishes the independent contributions of the two degradation driving forces and compensates them differently, eliminating grayscale response mismatch at the causal level and achieving pixel-level accurate brightness calibration.

Description

Technical Field

[0001] This invention belongs to the field of display panel brightness calibration technology, and relates to a method and system for calibrating and repairing the brightness of a display panel. Background Technology

[0002] Before leaving the factory, the display panel uses optical measurement equipment to collect brightness differences pixel by pixel and establish corresponding driving compensation relationships. During the display stage, point-by-point correction is applied to the input grayscale signal to achieve an initial uniform brightness across the entire screen. However, with the accumulation of usage time, each pixel undergoes inconsistent aging and degradation due to the different display loads it bears. The compensation relationship established at the factory gradually deviates from the actual deterioration state, causing the uneven brightness across the entire screen to reappear.

[0003] One existing approach is to periodically interrupt the use of the device and re-acquire the full-screen brightness and update the compensation relationship using external optical equipment. However, this approach has a high operational threshold and cannot be normalized. Another existing approach is to assume that the brightness decay of all pixels follows the same degradation trend and to perform overall scaling or uniform offset adjustment on the factory compensation relationship based on global statistical indicators such as the total working time of the panel or the average display intensity of the full screen.

[0004] However, the existing methods described above have the following technical drawbacks: 1. Inability to identify the differences in the causes of pixel brightness degradation: In actual use, the sources of degradation driving forces for different pixels differ: pixels that continuously display high grayscale content are mainly driven to age by their own current stress, while pixels adjacent to high-power pixels are mainly driven to age by thermal stress caused by heat conduction. The two degradation mechanisms have different distortion paths for the pixel's electro-optical characteristics, and the brightness compensation required for current stress-dominated degradation and thermal stress-dominated degradation under the same grayscale driving force does not have the same trend as the grayscale change. Existing technologies cover all pixels with a uniform degradation trend and use an indiscriminate compensation relationship for global adjustment, resulting in grayscale response mismatch in some pixels after compensation, which manifests as residual brightness deviation or even local color shift at the microscopic level.

[0005] 2. Lack of differentiated tracking and response capabilities for the evolution of individual pixel degradation features: Existing technologies rely on macroscopic statistical indicators for adjustment, which cannot reflect the individual differences in the proportion of local degradation stress experienced by each pixel due to differences in the details of the displayed content. This results in the same compensation amount being applied to pixels with completely different causes of degradation, and the problem of insufficient compensation for high-load pixels and excessive compensation for low-load pixels can never be eradicated. Summary of the Invention

[0006] In view of this, in order to solve the problems mentioned in the background art, a brightness calibration and repair method and system for display panels is proposed.

[0007] The objective of this invention can be achieved through the following technical solution: The first embodiment of this invention provides a brightness calibration and repair method for a display panel, including: obtaining the driving current time-series accumulation of each pixel as a first degradation characterization component, and the temperature time-series accumulation derived from the thermal conduction of neighboring pixels as a second degradation characterization component.

[0008] Using the current pixel brightness deviation as the reconstruction target and the degradation characterization components as decomposition factors, a retrospective decomposition is performed through brightness deviation reconstruction consistency constraints and spatial thermal field continuity constraints to obtain the independent contribution distribution of each degradation characterization component to brightness decay.

[0009] Using the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, the gain slope factor and intercept offset factor corresponding to the current degradation characteristic are determined according to the pre-established compensation parameter lookup table.

[0010] Substitute the current input grayscale value into the compensation calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel.

[0011] With the goal of minimizing the spatial gradient of the compensation amount between adjacent pixels, the initial compensation amount is iterated frame by frame to achieve smooth convergence, and the final compensation amount matrix of the current frame is output.

[0012] The second embodiment of the present invention provides a brightness calibration and repair system for a display panel, comprising: a degradation feature acquisition module, a degradation contribution decomposition module, a parameter addressing and matching module, an initial compensation calculation module, and a brightness compensation determination module.

[0013] The degradation feature acquisition module is connected to the degradation contribution decomposition module, the degradation contribution decomposition module is connected to the parameter addressing and matching module, the parameter addressing and matching module is connected to the initial compensation calculation module, and the initial compensation calculation module is connected to the brightness compensation determination module.

[0014] The degradation feature acquisition module acquires the time-series accumulation of the driving current of each pixel as the first degradation characterization component, and the time-series accumulation of the temperature derived from the thermal conduction of neighboring pixels as the second degradation characterization component.

[0015] The degradation contribution decomposition module uses the current brightness deviation value of the pixel as the reconstruction target and the degradation characterization components as the decomposition factors. It performs retrospective decomposition through brightness deviation reconstruction consistency constraints and spatial thermal field continuity constraints to obtain the independent contribution distribution of each degradation characterization component to brightness decay.

[0016] The parameter addressing and matching module uses the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, and determines the gain slope factor and intercept offset factor corresponding to the current degradation characteristic based on the pre-established compensation parameter lookup table.

[0017] The initial compensation calculation module substitutes the current input grayscale value into the compensation calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel.

[0018] The brightness compensation determination module aims to minimize the spatial gradient of the compensation amount between adjacent pixels. It performs frame-by-frame iterative smooth convergence on the initial compensation amount and outputs the final compensation amount matrix for the current frame.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention obtains the time-series accumulation of the driving current of each pixel as the first degradation characterization component and the time-series accumulation of the temperature derived from the thermal conduction of neighboring pixels as the second degradation characterization component, and performs retrospective decomposition using the two as decomposition factors to obtain the independent contribution distribution of each degradation characterization component to brightness decay, thereby restoring the same brightness deviation value to the degradation contribution of the two different degradation driving forces of current stress and thermal stress, directly distinguishing the cause type of pixel brightness decay, so that the subsequent compensation strategy can make decisions based on the degradation cause composition rather than the general decay magnitude.

[0020] (2) The present invention uses the ratio of each degradation characterization component in the independent contribution distribution as the addressing parameter to determine the corresponding gain slope factor and intercept offset factor, so that the compensation amount calculation relationship of each pixel is determined by the proportion of its own degradation cause. Current stress-dominated pixels and thermal stress-dominated pixels will be guided to different gain slopes and intercept offsets. The compensation amount changes with the input gray level automatically due to the difference in degradation causes, which helps to eliminate the gray level response mismatch problem caused by the existing technology of covering the whole screen pixels with a unified degradation curve.

[0021] (3) The present invention aims to minimize the spatial gradient of the compensation amount between adjacent pixels. It performs frame-by-frame iterative smooth convergence on the initial compensation amount of each pixel. The output of the current frame is the final compensation amount matrix after spatial neighborhood constraint correction. This allows each pixel to obtain differentiated compensation parameters while the jump in compensation amount between adjacent pixels is compressed frame by frame to a state of gradual spatial gradient convergence. The compensation amount maintains a continuous transition in the screen space, avoiding the introduction of new perceptible brightness boundaries in the image due to independent pixel compensation. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the implementation steps of the method of the present invention;

[0024] Figure 2 This is a flowchart illustrating the retrospective decomposition of the present invention.

[0025] Figure 3 This is a schematic diagram of the module connection of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1 As shown, the first embodiment of the present invention provides a brightness calibration and repair method for a display panel, including: S1. obtaining the cumulative amount of driving current timing of each pixel as a first degradation characterization component, and the cumulative amount of temperature timing derived from the thermal conduction of neighboring pixels as a second degradation characterization component.

[0028] In this embodiment, the first degradation characterization component includes the following acquisition process: in each sampling period, the instantaneous current flowing through the pixel driving transistor is sampled once through the sensing line to obtain the driving current sampling value; at the same time, the gate control signal of the pixel driving transistor is monitored for level, and the cumulative duration of the conduction level in the sampling period is recorded as the effective conduction duration of the corresponding pixel in the current sampling period.

[0029] Multiplying the sampled value of the driving current by the effective conduction time yields the single-frame electrical stress increment.

[0030] Using the current frame as the reference point, backtrack to the [frame number]. A frame is defined to identify the set of historical frames corresponding to the current frame, and the time distance of each historical frame in the set relative to the current frame is obtained; where The determination method is as follows: During the display panel model finalization stage, accelerated aging tests are conducted on panel samples from the same batch under continuous constant current stress. The time taken for the brightness to decay from the reference brightness to 90% of the reference brightness is recorded. The product of this time and the display frame rate is rounded up to obtain the result. .

[0031] The attenuation weight coefficient for each historical frame is determined using the following formula based on the time distance: .

[0032] In the formula, Let be the attenuation weight coefficient to be solved. The time distance between historical frames and the current frame, where the time distance refers to the frame interval. The decay feature frame number, in physical terms, means that the weights decay to... The number of frames required depends on the distance from the current frame. The weight of historical frames has decayed to In engineering terms, this can be considered as the contribution being almost completely diminished, therefore, in order to... The frame history set covers approximately 95% of the degradation contribution and should meet the following requirements. Accordingly, in If it is already determined, take for The rounded-up value is used to ensure that the weight of the furthest historical frame decays to about 5%, thus achieving a reasonable truncation of the historical stress contribution.

[0033] The product of the single-frame electrical stress increment of each historical frame and its corresponding attenuation weight coefficient is summed, and the summation result is used as the first degradation characterization component.

[0034] It should be noted that the attenuation weight coefficients of each historical frame are normalized before being used for cumulative calculation: each attenuation weight coefficient is divided by the sum of the attenuation weight coefficients of all historical frames, and the normalized attenuation weight coefficients are used in the weighted cumulative calculation of the degradation characterization components.

[0035] In this embodiment, the second degradation characterization component includes the following acquisition process: Pixels on the display panel are sequentially selected as target pixels in order from top to bottom and from left to right in each row, and for each target pixel, the following is performed: Determine the set of neighboring pixels with thermal conductivity relationship: Taking the row and column coordinates of the target pixel as the origin, expand outwards layer by layer along the row and column directions, and include all pixels other than the target pixel in the rectangular expansion area into the neighboring pixel set; wherein, the number of expansion layers is determined as follows: Extract the thermal conductivity and volumetric heat capacity of the display panel isolation layer material from the technical data provided by the material supplier, divide the thermal conductivity by the volumetric heat capacity to obtain the lateral thermal diffusivity; the lateral thermal diffusivity characterizes the rate of heat diffusion in the display surface direction.

[0036] The single-frame cycle duration of the display panel is obtained. The single-frame cycle duration is multiplied by the lateral heat diffusion coefficient and the square root is taken to obtain the single-frame heat diffusion characteristic length. The single-frame heat diffusion characteristic length represents the effective diffusion distance of heat along the display surface direction within one frame cycle.

[0037] Divide the length of the single-frame thermal diffusion feature by the pixel pitch of the display panel, and round up the quotient to the nearest integer as the number of expansion layers.

[0038] Obtain the temperature time series data of each neighboring pixel in the neighborhood pixel set within the historical frame set.

[0039] Based on the pre-calibrated thermal coupling coefficients of the pixel geometry and material thermal diffusion parameters, the temperature time series data of each neighboring pixel is multiplied by the corresponding thermal coupling coefficient and accumulated frame by frame to obtain the neighboring thermal contribution time series.

[0040] The product of the neighboring thermal contribution value and the corresponding attenuation weight coefficient in each frame of the neighboring thermal contribution time series is summed, and the summation result is used as the second degradation characterization component.

[0041] It should be noted that the pre-calibration process of the thermal coupling coefficient is as follows: during the panel material selection stage, the thickness, in-plane thermal conductivity and volumetric heat capacity of each layer in the stacked structure of each film layer above the self-emissive layer of the display panel are determined by standard thermal property testing methods (transient planar heat source method or laser flash method).

[0042] Using the finite element mesh method, the light-emitting layer plane of the display panel is discretized into an array of heat source nodes corresponding to each pixel, and each film layer is discretized into a layered thermal resistance-thermal capacity network along the longitudinal direction.

[0043] Apply a unit power excitation to each individual pixel node sequentially, while setting the power consumption of the remaining pixel nodes to zero. Write the thermal balance equation for each pixel node, in the form: .

[0044] in, pixel node heat capacity, This refers to the number of each pixel node. , pixel node temperature, Adjacent pixel nodes temperature, pixel node With pixel nodes Thermal resistance between pixel node The set of adjacent pixel nodes, pixel node Power consumption excitation.

[0045] pixel node rate of temperature change pixel node With pixel nodes Heat flow between pixels per unit time Transmitted to pixel nodes The calories.

[0046] The net inflow term for heat conduction in the neighborhood represents the total amount of heat transferred from all adjacent pixel nodes to the current pixel node via heat conduction. The sum of the heat input or output.

[0047] pixel node The heat storage item represents the heat that a node accumulates or releases due to temperature changes over time.

[0048] The equation means that the rate of change of heat storage of a pixel node is equal to the sum of the net heat flow from the neighborhood and the heat generated by its own power consumption.

[0049] The steady-state solution is obtained when the temperature change rate of all nodes in the screen approaches zero. The convergence criterion is that the maximum absolute value of the global node temperature change in the two iterations is lower than the preset temperature tolerance (0.01K), or the number of iterations reaches the preset upper limit (500 steps).

[0050] Record the steady-state temperature rise value of each pixel node, divide the steady-state temperature rise value of each response pixel node by the unit power consumption value, and use the quotient as the thermal coupling coefficient from the excitation pixel node to the response pixel node.

[0051] By traversing all pixel nodes in the screen as excitation sources and repeating the excitation and solution steps, the thermal coupling coefficient between pixel pairs in the entire screen can be obtained.

[0052] S2. Using the current pixel brightness deviation value as the reconstruction target and the degradation characterization component as the decomposition factor, a retrospective decomposition is performed through brightness deviation reconstruction consistency constraints and spatial thermal field continuity constraints to obtain the independent contribution distribution of each degradation characterization component to brightness decay.

[0053] Reference Figure 2 As shown, in this embodiment, the retrospective decomposition takes the current brightness deviation value of each pixel in the entire screen, the first degradation characterization component, and the second degradation characterization component as inputs, and uniformly solves the first brightness decay contribution and the second brightness decay contribution of all pixels in the entire screen. Specifically, it includes: using brightness deviation reconstruction consistency constraint as the main constraint and spatial thermal field continuity constraint as the penalty constraint.

[0054] The main constraint is manifested as the full-screen brightness deviation reconstruction error: for each pixel, the product of the first degradation characterization component and the first brightness decay contribution is added to the product of the second degradation characterization component and the second brightness decay contribution to obtain the reconstructed brightness deviation value.

[0055] The reconstructed brightness deviation is subtracted from the current brightness deviation value of the pixel and then squared to obtain the reconstruction mean square error of each pixel. The reconstruction mean square errors of all pixels in the screen are summed to obtain the total reconstruction mean square error. The main constraint requires minimizing the total reconstruction mean square error.

[0056] The penalty constraint requires that the sum of the squares of the differences in the contribution of the second brightness decay of any adjacent pixels be minimized; the range of adjacent pixels is taken as the four-neighbor area, specifically the top, bottom, left, and right adjacent pixels of the target pixel.

[0057] The full-screen brightness deviation reconstruction error and the full-screen spatial thermal field continuity penalty term are combined according to a preset ratio to form a comprehensive evaluation index; the preset ratio determines the relative weight between the main constraint and the penalty constraint, and its benchmark value is [value missing]. That is, the weight of the master constraint accounts for The weight of the penalty constraint accounts for .

[0058] The preset ratio is updated each time a retrospective decomposition is performed, based on the coefficient of variation of the second degradation characterization component of the full-screen pixels in the current frame. The coefficient of variation is the ratio of the standard deviation to the mean of the second degradation characterization component. The update rule is as follows: the sum of the coefficient of variation and 1 is used as an adjustment factor, which is multiplied by the main constraint weight in the baseline ratio. The penalty constraint weight remains unchanged. The two are then re-normalized and used as the comprehensive evaluation index combination ratio for the current frame.

[0059] The physical basis of this update rule is as follows: the coefficient of variation of the second degradation characterization component reflects the spatial dispersion of the full-screen thermal stress distribution. The larger the coefficient of variation, the more significant the difference in thermal stress between different pixels. By strengthening the weight of the main constraint, the accurate reconstruction of the brightness deviation of each pixel is guaranteed first under the condition of highly uneven thermal stress distribution. Conversely, the smaller the coefficient of variation, the more uniform the thermal stress distribution. By increasing the penalty constraint to regulate the continuity of the thermal field, overfitting is avoided.

[0060] Simultaneously, an amplitude limit constraint needs to be applied during the update process: if the weight percentage of the updated main constraint is lower than... Then the primary constraint will be forcibly reset to The penalty constraint weights are adjusted accordingly. This ensures that the weight of the primary constraint is always no less than that of the penalty constraint.

[0061] Using the first and second brightness decay contributions as variables to be solved, under the condition of satisfying the main constraints, the spatial distribution of the second brightness decay contribution is regularized by the penalty constraint, and the values ​​of the two contributions are iteratively adjusted along the direction of reducing the residual of the main constraints.

[0062] Specifically, the execution flow of the regularization adjustment is as follows: In each iteration, for each target pixel, the following is performed: extract the current value of the second brightness decay contribution of the target pixel in this iteration, calculate the absolute value of the difference between this value and the second brightness decay contribution of each adjacent pixel corresponding to the target pixel, and take the arithmetic mean as the spatial discontinuity measure.

[0063] The median value of the power consumption of all pixels in the row containing the target pixel is accumulated with the average inter-row thermal coupling coefficient and the normalization constant to obtain the allowable threshold. The average inter-row thermal coupling coefficient is the arithmetic mean of the thermal coupling coefficients of all pixels in the row containing the target pixel and the adjacent rows. The normalization constant is the ratio of the arithmetic mean of the absolute values ​​of the full-screen brightness deviation to the arithmetic mean of the first degradation characterization component of the full screen. The physical meaning of the allowable threshold is that the difference between the second contribution of a pixel and its neighborhood should not exceed the natural fluctuation range determined by the power consumption level and thermal conductivity of the corresponding row under normal thermal diffusion mechanism.

[0064] Compare the spatial discontinuity measure with the allowable threshold. If the former is greater than the latter, multiply the excess by the penalty intensity factor to obtain the penalty adjustment amount; otherwise, the penalty adjustment amount is zero. The penalty intensity factor is obtained as follows: in the first iteration, the penalty intensity factor is set to 1; from the second iteration onwards, the penalty intensity factor is the ratio of the main constraint residual of the current iteration to the main constraint residual of the previous iteration, and when the main constraint residual of the previous iteration is 0, the penalty intensity factor is set to 1. The main constraint residual specifically refers to the total mean square error of reconstruction mentioned above.

[0065] The penalty adjustment is superimposed on the second brightness decay contribution of the target pixel in the direction of negative feedback: when the second contribution of the target pixel is higher than its neighborhood mean, the penalty adjustment is subtracted; when it is lower than the neighborhood mean, the penalty adjustment is added. The superimposed result is used as the updated value of the second brightness decay contribution of the target pixel after regularization adjustment.

[0066] The iterative adjustment of the values ​​of the two contributions along the direction of reducing the residual of the main constraint includes: first, substituting the first brightness decay contribution and the second brightness decay contribution of this round into the reconstruction relation to calculate the residual between the reconstructed brightness deviation and the measured brightness deviation; and using the first degradation characterization component multiplied by the residual as the update gradient of the first contribution, and using the second degradation characterization component multiplied by the residual as the update gradient of the second contribution.

[0067] Secondly, update the two contribution values ​​in the direction of reducing residuals: the first contribution value minus the product of its update gradient and the main iteration step size, and the second contribution value minus the product of its update gradient and the main iteration step size; the main iteration step size is the reciprocal of the larger value between the first degradation characterization component and the second degradation characterization component, and multiplied by the decay factor of this round. The decay factor is 1 in the first round, and multiplied by a preset decay coefficient less than 1 in each subsequent round (it can be 0.9, so that the step size gradually shrinks as the iteration progresses).

[0068] Next, regularization adjustment is applied to the updated second contribution value pixel by pixel, the penalty adjustment amount is calculated and superimposed in the negative feedback direction to obtain the regularized second contribution value; the first contribution value does not participate in the regularization adjustment.

[0069] Finally, the total mean square error of reconstruction is recalculated using the regularized second contribution and the updated first contribution, and used as the residual record of the master constraint in this round.

[0070] The iteration terminates when the master constraint residuals meet the convergence condition, and the first and second brightness decay contribution values ​​are output as the independent contribution distribution of each degradation characterization component to brightness decay.

[0071] It should be added that the convergence criterion is as follows: calculate the absolute value of the difference between the residual of the current master constraint and the residual of the previous master constraint, and use this as the jump variable of the current residual; when the number of iterations completed is less than 3, convergence is not performed, and the process proceeds directly to the next iteration; after the cumulative number of iterations reaches 3, sort the jump variables of the residuals from the previous iterations in ascending order, and take the first one after sorting. The position value is rounded down to serve as the convergence threshold. If the decrease in the residual of the main constraint in this round relative to the residual of the main constraint in the previous round is less than the convergence threshold, then convergence is determined and the iteration terminates. In addition, the ratio of the absolute value of the residual in the first round to the initial value of the main iteration step size is rounded up to obtain the upper limit of the iterations. If convergence is not achieved after reaching the upper limit of iterations, the iteration is also terminated.

[0072] In the above decomposition process, the dimension of the first brightness decay contribution is the cumulative brightness per current-time, which represents the amount of brightness decay caused by the product stress of a unit driving current and a unit time for a pixel; the dimension of the second brightness decay contribution is the cumulative brightness per temperature-time, which represents the amount of brightness decay caused by the product stress of a unit temperature and a unit time for a pixel.

[0073] S3. Using the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, determine the gain slope factor and intercept offset factor corresponding to the current degradation characteristic based on the pre-established compensation parameter lookup table.

[0074] In this embodiment, the compensation parameter lookup table includes the following pre-establishment process: selecting multiple aging test samples of the same model as the target display panel, conducting accelerated aging experiments under different driving current stresses and ambient temperatures, measuring the brightness deviation value, first degradation characterization component, and second degradation characterization component of each pixel of each sample at different aging stages; for each measured sample, taking the negative value of the brightness deviation value at the same aging stage as the required brightness compensation amount in that state, which is expressed as the brightness correction amount required to restore the pixel to the target brightness.

[0075] The ratio of the first independent contribution to the second independent contribution of each pixel under each aging state is calculated as the sample addressing parameter. After collecting all sample addressing parameters, an equal-width histogram is constructed along the addressing parameter axis from the minimum to the maximum value. The frequency of each histogram interval is counted. The sign of the frequency change rate between adjacent intervals is calculated. If the sign changes from positive to negative or from negative to positive, the boundary between adjacent intervals is marked as the density boundary point. The addressing parameter axis is divided into multiple continuous non-equal-width intervals using all density boundary points as the dividing positions.

[0076] Within each addressing interval, with the input grayscale as the independent variable and the required brightness compensation amount as the dependent variable, a least-squares linear fit is performed on all data points within the addressing interval. The slope of the fitted line is extracted as the gain slope factor corresponding to the addressing interval, and the intercept is used as the intercept offset factor corresponding to the interval. The physical dimension of the gain slope factor is brightness units per grayscale, representing the increase in brightness compensation required for each unit increase in driving grayscale under the current pixel degradation characteristics. The physical dimension of the intercept offset factor is brightness units, representing the basic offset compensation amount when the grayscale returns to zero under the linear compensation relationship corresponding to the gain slope factor.

[0077] A lookup table is established with the addressing interval index as the key and the gain slope factor and intercept offset factor as the values. The addressing interval index is generated by the addressing parameters of the current pixel after interval positioning judgment.

[0078] In this embodiment, determining the gain slope factor and intercept offset factor corresponding to the current degradation feature includes: calculating the addressing parameters of the current pixel and comparing them with the boundary values ​​of each addressing interval in the compensation parameter lookup table; if the addressing parameters fall within a certain addressing interval, then the gain slope factor and intercept offset factor corresponding to that addressing interval are directly taken.

[0079] If the addressing parameter falls outside all addressing intervals, then the gain slope factor and intercept offset factor of the nearest and second nearest intervals are linearly interpolated to obtain the gain slope factor and intercept offset factor that are adapted to the current addressing parameter.

[0080] The selection of the nearest and second nearest intervals includes two cases: one is that the addressing parameter is less than the minimum lower boundary of all addressing intervals, and the nearest interval is determined as the first addressing interval and the second nearest interval is determined as the second addressing interval; the other is that the addressing parameter is greater than the maximum upper boundary of all addressing intervals, and the nearest interval is determined as the last addressing interval and the second nearest interval is determined as the penultimate addressing interval.

[0081] The specific process of linear interpolation is as follows: calculate the distance from the addressing parameter to the nearest interval center value, and the ratio of the distance from the second nearest interval center value to the nearest interval center value, as the interpolation weight; the range of the interpolation weight is [0,1], the closer to the nearest interval the weight tends to 0, and the closer to the second nearest interval the weight tends to 1.

[0082] The interpolated gain slope factor is obtained by multiplying the gain slope factor of the nearest interval by 1 and the interpolation weight, and then adding the gain slope factor of the second nearest interval multiplied by the interpolation weight. The intercept offset factor is interpolated in the same way.

[0083] S4. Substitute the current input grayscale value into the compensation calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel.

[0084] In this embodiment, generating the initial compensation amount for each pixel includes: obtaining the input grayscale value of the current frame, multiplying it by the gain slope factor to obtain a product term.

[0085] Add the product term to the intercept offset factor to obtain the initial brightness compensation value.

[0086] For each pixel, retrieve the calibration ratio of its maximum brightness measured during the panel's factory calibration phase to the maximum value of the driving electrical parameters, and divide the initial brightness compensation value by the calibration ratio to obtain the driving electrical parameter compensation value.

[0087] The driving electrical parameter compensation value is used as the initial compensation value, wherein the driving electrical parameter is the conduction current between the source and drain of the pixel driving transistor, or the control voltage between the gate and source of the pixel driving transistor.

[0088] S5. With the goal of minimizing the spatial gradient of the compensation amount between adjacent pixels, the initial compensation amount is iterated frame by frame to achieve smooth convergence, and the final compensation amount matrix of the current frame is output.

[0089] In this embodiment, the step of performing frame-by-frame iterative smooth convergence of the initial compensation amount includes: using the row coordinates of each pixel on the display panel as the row index and the column coordinates as the column index, and using the initial compensation amount of each pixel as the matrix element value at the corresponding position to construct a compensation amount matrix.

[0090] Using the row and column coordinates of a pixel as a reference, the sum of the absolute values ​​of the differences between the compensation amount of each pixel and the compensation amount of its neighboring pixels is calculated as the local spatial gradient.

[0091] The iteration step size factor is dynamically set based on the spatial non-uniformity prediction of the display panel: During the manufacturing stage of the display panel, the brightness distribution of each pixel under full white field is collected by illuminating with a planar light source, and the standard deviation of the brightness difference between adjacent pixels is calculated as the benchmark value of spatial non-uniformity.

[0092] After the compensation matrix for the current frame is constructed, the sum of the local spatial gradients of all pixels on the screen is calculated as the global spatial gradient sum. The ratio obtained by dividing the spatial non-uniformity benchmark value by the global spatial gradient sum is multiplied by a scaling constant and used as the iteration step size factor for the current frame. The scaling constant is determined by running a smooth iteration process with different scaling factors in simulation verification of the same model panel and recording the number of iterations required to reach convergence. The maximum value that makes the number of convergence iterations fall within the processing time margin per frame supported by the display frame rate is selected as the scaling constant and stored in non-volatile memory.

[0093] In addition, when the sum of global spatial gradients is less than the preset minimum threshold, the iteration step size factor is set to 0, the smooth iteration of the current frame is skipped, and the initial compensation amount is directly used as the final compensation amount for output.

[0094] The compensation amount of each pixel is updated along the direction of local spatial gradient descent. The update amount is the iteration step size factor multiplied by the difference between the current pixel compensation amount and the average compensation amount of the neighboring pixels.

[0095] After each update, the global spatial gradient sum of the full-screen compensation matrix is ​​recalculated. If the decrease in the global spatial gradient sum of the current frame compared to the previous iteration is less than a preset convergence tolerance, or if the number of iterations reaches a preset maximum number of iterations, then the iteration is considered to have converged, and the final compensation matrix of the current frame is output. The preset convergence tolerance is taken as the global spatial gradient sum calculated in the first iteration before the start of this iteration. The preset maximum number of iteration rounds is taken as the minimum value between the row resolution and column resolution of the display panel. The maximum number of iterations is set to at least 1. When the calculated value is less than 1, it is set to 1. The corresponding physical basis is that the minimum number of iterations required for spatial gradient information to be transferred from one edge pixel to the opposite edge pixel through adjacent pixels is half the width of the panel. Half of this value is taken as a sufficiently conservative estimate.

[0096] It should be noted that this invention also adds an oscillation detection mechanism: if the difference between the maximum and minimum values ​​of the sum of global spatial gradients in three consecutive iterations is less than the sum of global spatial gradients in the first iteration... If the condition is met, it is considered that the system has entered a stable oscillation state, and the iteration is terminated directly, and the compensation matrix of the current round is output.

[0097] Reference Figure 3 As shown, the second embodiment of the present invention provides a brightness calibration and repair system for a display panel, including: a degradation feature acquisition module, a degradation contribution decomposition module, a parameter addressing and matching module, an initial compensation calculation module, and a brightness compensation determination module.

[0098] The degradation feature acquisition module is connected to the degradation contribution decomposition module, the degradation contribution decomposition module is connected to the parameter addressing and matching module, the parameter addressing and matching module is connected to the initial compensation calculation module, and the initial compensation calculation module is connected to the brightness compensation determination module.

[0099] The degradation feature acquisition module acquires the time-series accumulation of the driving current of each pixel as the first degradation characterization component, and the time-series accumulation of the temperature derived from the thermal conduction of neighboring pixels as the second degradation characterization component.

[0100] The degradation contribution decomposition module uses the current brightness deviation value of the pixel as the reconstruction target and the degradation characterization components as the decomposition factors. It performs retrospective decomposition through brightness deviation reconstruction consistency constraints and spatial thermal field continuity constraints to obtain the independent contribution distribution of each degradation characterization component to brightness decay.

[0101] The parameter addressing and matching module uses the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, and determines the gain slope factor and intercept offset factor corresponding to the current degradation characteristic based on the pre-established compensation parameter lookup table.

[0102] The initial compensation calculation module substitutes the current input grayscale value into the compensation calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel.

[0103] The brightness compensation determination module aims to minimize the spatial gradient of the compensation amount between adjacent pixels. It performs frame-by-frame iterative smooth convergence on the initial compensation amount and outputs the final compensation amount matrix for the current frame.

[0104] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A method for repairing luminance calibration of a display panel, characterized in that, include: The driving current time-series accumulation of each pixel is obtained as the first degradation characterization component, and the temperature time-series accumulation derived from the thermal conduction of neighboring pixels is obtained as the second degradation characterization component. Using the current pixel brightness deviation as the reconstruction target and the degradation characterization component as the decomposition factor, a retrospective decomposition is performed through brightness deviation reconstruction consistency constraints and spatial thermal field continuity constraints to obtain the independent contribution distribution of each degradation characterization component to brightness decay. Using the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, the gain slope factor and intercept offset factor corresponding to the current degradation characteristic are determined according to the pre-established compensation parameter lookup table. Substitute the current input grayscale value into the compensation calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel. With the goal of minimizing the spatial gradient of the compensation amount between adjacent pixels, the initial compensation amount is iterated frame by frame to achieve smooth convergence, and the final compensation amount matrix of the current frame is output. 2.The brightness calibration repair method of a display panel according to claim 1, wherein, The first degradation characterization component includes the following acquisition process: Obtain the sampled value of the driving current flowing through the pixel, and obtain the effective conduction time of the pixel within the corresponding sampling period; Multiply the sampled value of the driving current by the effective conduction time to obtain the single-frame electrical stress increment; Determine the set of historical frames corresponding to the current frame, and obtain the time distance of each historical frame in the set relative to the current frame; The attenuation weight coefficient for each historical frame is determined based on the time distance. The product of the single-frame electrical stress increment of each historical frame and its corresponding attenuation weight coefficient is summed, and the summation result is used as the first degradation characterization component. 3.The brightness calibration repair method of the display panel according to claim 2, characterized in that, The second degradation characterization component includes the following acquisition process: For the target pixel, determine the set of neighboring pixels that have a thermal conduction relationship; Obtain the temperature time-series data of each neighboring pixel in the neighborhood pixel set within the historical frame set; Based on the pre-calibrated thermal coupling coefficients of the pixel geometry and material thermal diffusion parameters, the temperature time series data of each neighboring pixel is multiplied by the corresponding thermal coupling coefficient and accumulated frame by frame to obtain the neighboring thermal contribution time series. The product of the neighboring thermal contribution value and the corresponding attenuation weight coefficient in each frame of the neighboring thermal contribution time series is summed, and the summation result is used as the second degradation characterization component. 4.The brightness calibration repair method of the display panel according to claim 1, wherein, The retrospective decomposition, which reconstructs consistency constraints and spatial thermal field continuity constraints through brightness deviation, includes: The consistency constraint of brightness deviation reconstruction is the main constraint, and the continuity constraint of spatial thermal field is the penalty constraint. The main constraint requires that the product of the first degradation characterization component and the first brightness decay contribution, plus the product of the second degradation characterization component and the second brightness decay contribution, should minimize the mean square error of the reconstruction of the current brightness deviation value by the linear superposition result. The penalty constraint requires that the sum of the squares of the differences in the second brightness decay contribution of any adjacent pixels be minimized; Using the first and second brightness decay contributions as variables to be solved, under the condition of satisfying the main constraints, the spatial distribution of the second brightness decay contribution is regularized by the penalty constraint, and the values ​​of the two contributions are iteratively adjusted along the direction of reducing the residual of the main constraints. The iteration terminates when the master constraint residuals meet the convergence condition, and the first and second brightness decay contribution values ​​are output as the independent contribution distribution of each degradation characterization component to brightness decay.

5. The method of claim 1, wherein the method further comprises: The compensation parameter lookup table includes the following pre-establishment process: Multiple aging test samples of the same model as the target display panel were selected and accelerated aging experiments were conducted under different driving current stresses and ambient temperatures. The brightness deviation value, first degradation characterization component and second degradation characterization component of each pixel of each sample were measured at different aging stages. The ratio of the first independent contribution to the second independent contribution of each pixel under each aging state is calculated as the sample addressing parameter. The probability density distribution of all sample addressing parameters is statistically analyzed, and the sample addressing parameters are divided into multiple continuous non-equal width intervals. Within each addressing interval, with the input grayscale as the independent variable and the required brightness compensation amount as the dependent variable, least-squares linear fitting is performed on all data points within the addressing interval. The slope of the fitted line is extracted as the gain slope factor corresponding to the addressing interval, and the intercept is used as the intercept offset factor corresponding to the addressing interval. A lookup table is established with the addressing interval index as the key and the gain slope factor and intercept offset factor as the values. The addressing interval index is generated by the addressing parameters of the current pixel after interval positioning judgment.

6. The brightness calibration repair method of a display panel according to claim 5, wherein, The determination of the gain slope factor and intercept offset factor corresponding to the current degradation characteristics includes: Calculate the addressing parameters of the current pixel and compare them with the boundary values ​​of each addressing interval in the compensation parameter lookup table: If the addressing parameter falls within a certain addressing interval, then the gain slope factor and intercept offset factor corresponding to that addressing interval are directly taken. If the addressing parameter falls outside all addressing intervals, then the gain slope factor and intercept offset factor of the nearest and second nearest intervals are linearly interpolated to obtain the gain slope factor and intercept offset factor that are adapted to the current addressing parameter.

7. The method of claim 1, wherein the method further comprises: The initial compensation amount for each pixel includes: Obtain the grayscale value of the current frame input, multiply it by the gain slope factor, and obtain the product term; Add the product term to the intercept offset factor to obtain the initial brightness compensation value; For each pixel, retrieve the calibration ratio between the maximum brightness measured during the panel factory calibration phase and the maximum value of the driving electrical parameters, divide the initial brightness compensation value by the calibration ratio, and obtain the driving electrical parameter compensation value. The driving electrical parameter compensation value is used as the initial compensation value, wherein the driving electrical parameter is the conduction current between the source and drain of the pixel driving transistor, or the control voltage between the gate and source of the pixel driving transistor. 8.The brightness calibration repair method of the display panel of claim 1, wherein, The step of performing frame-by-frame iterative smooth convergence of the initial compensation amount includes: Using the row coordinates of each pixel on the display panel as the row index and the column coordinates as the column index, the initial compensation amount of each pixel is used as the matrix element value at the corresponding position to construct the compensation amount matrix; Based on the row and column coordinates of the pixel, the sum of the absolute values ​​of the differences between the compensation amount of each pixel and the compensation amount of the neighboring pixels is calculated as the local spatial gradient. Set the iteration step size factor, update the compensation amount of each pixel along the direction of local spatial gradient descent, and the update amount is the iteration step size factor multiplied by the difference between the current pixel compensation amount and the average compensation amount of the four neighboring pixels. After each update, the sum of global spatial gradients of the full-screen compensation matrix is ​​recalculated. If the decrease in the sum of global spatial gradients in the current frame compared to the previous iteration is less than the preset convergence tolerance, or if the number of iterations reaches the preset maximum number of iterations, then the iteration is determined to be converged, and the final compensation matrix of the current frame is output. 9.The brightness calibration repair method of claim 8, wherein, The iteration step size factor is dynamically set based on the estimated spatial non-uniformity of the display panel, including: During the manufacturing process of the display panel, the brightness distribution of each pixel under full white field is collected by illuminating it with a planar light source, and the standard deviation of the brightness difference between adjacent pixels is calculated as a reference value for spatial non-uniformity. The iteration step size factor is obtained by scaling the ratio of the spatial non-uniformity benchmark value to the sum of the global spatial gradients.

10. A brightness calibration repair system of a display panel, characterized by, include: The degradation feature acquisition module acquires the time-series accumulation of the driving current of each pixel as the first degradation characterization component, and the time-series accumulation of the temperature derived from the thermal conduction of neighboring pixels as the second degradation characterization component. The degradation contribution decomposition module takes the current brightness deviation value of the pixel as the reconstruction target and the degradation characterization component as the decomposition factor. It performs retrospective decomposition through brightness deviation reconstruction consistency constraint and spatial thermal field continuity constraint to obtain the independent contribution distribution of each degradation characterization component to brightness decay. The parameter addressing and matching module uses the ratio of each degradation characteristic component in the independent contribution distribution as the addressing parameter, and determines the gain slope factor and intercept offset factor corresponding to the current degradation characteristic based on the pre-established compensation parameter lookup table. The initial compensation calculation module substitutes the current input grayscale value into the compensation amount calculation relationship determined by the gain slope factor and the intercept offset factor to generate the initial compensation amount for each pixel. The brightness compensation determination module aims to minimize the spatial gradient of the compensation amount between adjacent pixels. It performs frame-by-frame iterative smooth convergence on the initial compensation amount and outputs the final compensation amount matrix for the current frame.

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