VCOM Shift Compensation in LCD Driving via Grayscale Lookup Tables
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Solution Overview
Problem
Existing display technologies, such as TFT-LCDs, face issues with color shift and line image sticking due to uneven distribution of positive and negative polarity voltages, which cannot be effectively compensated in real time, especially in regions with poor panel characteristics.
Innovation Solution
A display driving method that calculates the VCOM shift amplitude for each row of sub-pixels based on grayscale data voltages and compensates the grayscale data voltages using a compensation table to offset the VCOM shift, thereby reducing color shift and other display errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If grayscale data voltages are directly input without compensation, then the display can operate with simple driving circuitry, but color shift and line image sticking occur due to VCOM shift
Solution Approach 1:
The patent pre-calculates and stores compensation values in a lookup table before actual display operation. The compensation table is generated by simulating VCOM shift effects for different grayscale patterns, allowing real-time compensation without complex calculations during display operation
Solution Approach 2:
The patent introduces a compensation table as an intermediary between the image data and the display panel. This table stores pre-computed voltage compensation values that mediate the interaction between input images and panel characteristics, eliminating the need for complex real-time compensation circuits
2Manufacturing precision
If VCOM shift compensation is implemented in real-time through calculation, then color shift and display errors are reduced, but RC delay limits the compensation speed and effectiveness
Solution Approach 1:
The compensation values are pre-calculated and stored in a lookup table during manufacturing or initialization. This eliminates the need for real-time mathematical calculations during display operation, thereby overcoming RC delay limitations and enabling fast compensation response
Solution Approach 2:
The patent creates a digital model (compensation table) that copies and stores the complex relationship between grayscale patterns and VCOM shift effects. This digital copy allows rapid retrieval of compensation values without performing the actual physical calculations during display operation
3Device complexity
If a fixed compensation value is applied to all regions, then the driving circuitry is simplified, but regions with poor panel characteristics cannot be effectively compensated
Solution Approach 1:
The patent divides the display panel into multiple regions (e.g., center region and corner regions) and generates separate compensation values for each region based on their specific characteristics. This allows each region to receive customized compensation tailored to its local panel characteristics, improving overall compensation effectiveness
Solution Approach 2:
The compensation approach is segmented by region, with different compensation strategies applied to different areas of the display panel. The lookup table is organized to provide region-specific compensation values, allowing the system to address local variations in panel performance without requiring a completely complex customized circuit for each region
Data Source
AI summary
The present disclosure is related to a display driving method. The display driving method may include obtaining a grayscale data voltage compensation table; calculating a value of VCOM shift amplitude corresponding to a row of sub-pixels on a display panel based on grayscale data voltages of a frame of an image to be displayed; obtaining a grayscale data voltage compensation value corresponding to the row of sub-pixels on the display panel based on the calculated value of VCOM shift amplitude and the grayscale data voltage compensation table; compensating grayscale data voltages actually inputted to the row of sub-pixels based on the grayscale data voltage compensation value to obtain compensated grayscale data voltages; and outputting the compensated grayscale data voltages to the row of sub-pixels during a display time of the frame of the image to be displayed.