Timing Controller IR-Drop Compensation for OLED Displays
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Solution Overview
Problem
Large-scale OLED displays experience brightness degradation due to the IR-Drop phenomenon, where power supply voltage drops across longer conductive lines, leading to non-uniform display brightness.
Innovation Solution
A timing controller with an image compensator that divides input images into blocks, selects central column pixels, calculates average representative gray levels, and applies gains from lookup tables to compensate for IR-Drop effects, generating compensated image data to maintain uniform brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display panel is scaled up to large size, then the display area is increased, but the conductive line length increases causing voltage drop and brightness non-uniformity
Solution Approach 1:
The patent divides the display panel into multiple regions based on conductive line lengths, with each region having its own compensation parameters stored in lookup tables. This segmentation allows different brightness compensation to be applied to different areas, resolving the brightness uniformity issue in large-scale displays
Solution Approach 2:
The patent applies different compensation gains to different regions of the display panel based on their specific conductive line characteristics. By storing and applying region-specific compensation parameters in lookup tables, the system achieves local optimization of brightness uniformity across the entire large-scale display
2Area of stationary object
If the conductive line length is increased to cover larger display area, then the display area is expanded, but the electrical resistance increases causing voltage drop
Solution Approach 1:
The patent pre-calculates and stores compensation parameters in lookup tables during the design phase, based on simulated or measured voltage drop characteristics of different regions. This preliminary action allows the system to compensate for voltage drop effects without requiring real-time measurement or complex calculations during operation
Solution Approach 2:
The patent changes the gray level parameters of pixels based on their location-specific compensation gains retrieved from lookup tables. By adjusting the driving voltage parameters (gray levels) according to regional voltage drop characteristics, the system compensates for energy loss in long conductive lines
3Illumination intensity
If lookup tables with region-specific compensation parameters are used, then brightness uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent uses lookup tables that store pre-calculated compensation parameters, effectively creating a simplified model of the complex voltage drop characteristics. Instead of implementing complex real-time calculations, the system copies and applies pre-determined compensation values from the lookup tables, reducing computational complexity while maintaining brightness uniformity
Data Source
AI summary
A timing controller includes an image compensator for generating compensated image data. The image compensator is configured to: divide an input image into plural image blocks; select plural pixels located at one column of the image block as plural target pixels; generate an average representative gray level of the image block according to a histogram of gray levels of the image block; input the average representative gray level into a first lookup table to obtain a first gain; input a vertical pixel position of the target pixel and the average representative gray level into a second lookup table to obtain a second gain; obtain the compensated gray level by multiplying the gray level, the first gain, and the second gain of the target pixel; and replace the gray levels with the compensated gray levels to acquire the compensated image data.