OLED Sub-frame Compensation for Aging Threshold Voltage
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Solution Overview
Problem
The quality of OLED-based display pixels is affected by changes in threshold voltage and mobility over time, making it challenging to maintain image quality and achieve higher luminance levels within the parameters of image data.
Innovation Solution
The system divides each frame into sub-frames, supplies image data during one sub-frame and compensation data during another, and adjusts the drive current based on compensated image data to compensate for aging parameters, allowing for higher luminance levels and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher luminance levels are used for compensation, then compensation accuracy is improved, but the image data parameters are exceeded and desired luminance levels are not achievable
Solution Approach 1:
The frame period is divided into multiple sub-frames, with specific sub-frames designated for compensation purposes. This segmentation allows the system to allocate dedicated time resources for compensation without affecting the overall image display requirements, enabling higher luminance levels during compensation sub-frames while maintaining image data parameters for display sub-frames.
Solution Approach 2:
Compensation is performed in advance during dedicated compensation sub-frames before the actual image display sub-frames. This preliminary action allows the system to adjust transistor parameters (threshold voltage, mobility) before they affect image quality, using higher luminance levels that would not be appropriate during normal image display.
2Measurement precision
If compensation data is transferred to a different sub-frame when exceeding driver resolution, then compensation accuracy is maintained, but additional sub-frame management complexity is introduced
Solution Approach 1:
The system dynamically determines whether compensated image data exceeds driver resolution and conditionally transfers excess data to different sub-frames. This dynamic approach allows the system to adapt its data management strategy based on real-time conditions, maintaining compensation accuracy while minimizing unnecessary complexity by only implementing additional sub-frame management when required.
3Manufacturing precision
If the sub-frame supplied with image data is longer than the sub-frame supplied with compensation data, then image quality is maintained, but the frame time allocation becomes asymmetric
Solution Approach 1:
Different sub-frames are allocated different durations and functions based on their specific requirements. Image display sub-frames are made longer to ensure sufficient time for high-quality image rendering, while compensation sub-frames are shorter as they only require brief periods for parameter adjustment. This local quality approach optimizes each sub-frame's duration for its specific purpose, maintaining image quality while efficiently utilizing frame time.
Data Source
AI summary
A system uses image data, representing images to be displayed in successive frames, to drive a display having pixels that include a drive transistor and an organic light emitting device by dividing each frame into at least first and second sub-frames, supplying the image data during one of the sub-frames, supplying compensation data during the other of the sub-frames, compensating image data based on the compensation data, and supplying each pixel with a drive current that is based on the compensated image data during each frame. The compensated image data may be supplied from a driver having a preselected data resolution, and the system determines whether the compensated image data is greater than the data resolution of the driver, and if the compensated image data is greater than the data resolution of the driver, transfers the excess compensated image data to a different sub-frame.