Voltage Drop Compensation in Display Panels Using Lookup Tables
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Solution Overview
Problem
Display devices, particularly active matrix flat panel displays, experience non-uniform luminance and color due to voltage drops along the display panel, especially in organic light emitting devices, caused by resistances and RC delays, leading to decreased display quality.
Innovation Solution
A method and system for voltage drop compensation using a maximum compensation voltage table and a voltage drop coefficient table to calculate and apply a voltage drop compensation voltage, which is calculated based on total output currents and XY coordinates, ensuring uniform luminance and color across the display panel by adding the compensation voltage to pre-compensation data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage lines are used to drive display panels, then the display device can be operated, but voltage drops occur due to resistances and RC delays causing non-uniform luminance and color
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation voltage values in lookup tables (MLEC LUT and LEC LUT) before actual display operation. The maximum compensation voltage table stores pre-computed voltage compensation values for maximum current conditions, while the voltage drop coefficient table provides coefficients for different current levels. This allows the system to proactively compensate for voltage drops without requiring real-time measurement and calculation during display operation.
Solution Approach 2:
The patent changes the voltage parameter dynamically based on current conditions. By calculating the total output current during one frame and using this to select appropriate compensation values from lookup tables, the system adjusts the compensation voltage according to actual operating conditions. This parameter change approach allows the system to adapt to varying current levels and maintain uniform luminance across different display regions.
2Manufacturing precision
If compensation voltage is calculated for each pixel position, then luminance uniformity is improved, but memory capacity requirements increase
Solution Approach 1:
The patent applies local quality by providing different compensation voltages for different regions of the display panel. The maximum compensation voltage table contains entries corresponding to different XY coordinates, allowing each pixel position to receive location-specific compensation. This regional differentiation addresses the varying voltage drop characteristics across different areas of the panel without requiring uniform compensation throughout.
Solution Approach 2:
The patent reduces memory requirements by changing from storing complete compensation voltage maps to storing lookup tables with discrete entries. The MLEC LUT stores maximum compensation voltages for key positions, while the LEC LUT stores voltage drop coefficients for different current levels. This parameter transformation allows the system to compute compensation values on-demand rather than storing all possible values, significantly reducing memory capacity requirements.
3Reliability
If voltage drop compensation is applied, then non-uniform luminance and color are reduced, but calculation complexity increases
Solution Approach 1:
The patent simplifies the calculation process by performing complex voltage drop calculations in advance during system initialization or calibration. The lookup tables (MLEC LUT and LEC LUT) are pre-filled with compensation values and coefficients, transforming the real-time calculation task into simple table lookup operations during actual display operation. This preliminary action significantly reduces the computational burden during runtime.
Solution Approach 2:
The patent uses lookup tables as pre-computed copies of the complex calculation results. Instead of performing complex voltage drop calculations for each pixel in real-time, the system uses pre-stored lookup table entries that represent the results of these calculations. This copying approach maintains the accuracy of voltage drop compensation while dramatically simplifying the real-time processing requirements.
Data Source
AI summary
The present invention relates to a method for compensating voltage drop of a display device, a system for voltage drop compensation, and a display device including the same. A method for compensating a voltage drop of a display device including a display panel, a maximum compensation voltage table MLEC LUT for voltage compensation when a voltage drop is a maximum in the display panel, and a voltage drop coefficient table LEC LUT representing voltage drop coefficients with respect to total output currents during one frame according to an embodiment of the present invention comprises: receiving an input image signal; gamma-converting the input image signal to obtain a pre-compensation data voltage; obtaining a first total output current flowing in all pixels PX of the display panel during one frame based on the input image signal; obtaining a first voltage drop compensation voltage V_LEC based on the voltage drop coefficient table LEC LUT and the maximum compensation voltage table MLEC LUT; and adding the first voltage drop compensation voltage V_LEC to the pre-compensation data voltage to obtain the post-compensation data voltage.