Display Device Shift Clock Pulse Width Adjustment for Luminance Uniformity
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Solution Overview
Problem
Organic light-emitting display devices face issues with luminance uniformity due to deviations in sensing periods and IR drop, leading to variations in electrical characteristics across pixels, especially at different grayscale levels and screen positions.
Innovation Solution
A display device and method that adjust the pulse width and voltage of the shift clock in real-time based on feedback signals to equalize sensing periods across the screen, using a sensing device to detect pulse widths and a driving device to generate the shift clock, thereby compensating for IR drop and electrical characteristic deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed sensing period is used for all pixels, then the control is simple, but luminance uniformity deteriorates due to RC delay variations in different screen positions
Solution Approach 1:
The patent applies dynamics by making the sensing period variable instead of fixed. The sensing period is dynamically adjusted based on the screen position to compensate for RC delay variations. Different sensing periods are applied to different regions (e.g., first sensing period for first region, second sensing period for second region), thereby maintaining luminance uniformity across the display panel.
Solution Approach 2:
The patent applies local quality by tailoring the sensing period to specific local regions of the display panel. Each region has its own optimized sensing period that accounts for local RC delay characteristics. This localized approach ensures that each pixel region experiences appropriate sensing timing, improving overall luminance uniformity.
2Measurement precision
If the gate signal on-time is extended to compensate for RC delay, then sensing accuracy improves, but the display response time deteriorates
Solution Approach 1:
The patent uses dynamics to adjust the gate signal on-time based on the specific needs of different pixel regions. Instead of using a uniformly extended on-time that would slow down the entire display, the on-time is dynamically extended only for regions experiencing RC delay, thereby maintaining sensing accuracy without unnecessarily extending the overall display response time.
Solution Approach 2:
The patent applies local quality by extending the gate signal on-time selectively for specific regions that have RC delay issues. Regions without significant RC delay use the standard on-time, thus maintaining fast response. This localized extension ensures sensing accuracy where needed while preserving overall display speed.
3Manufacturing precision
If internal compensation circuit is embedded in each pixel, then manufacturing complexity increases, but electrical characteristic deviation is reduced
Solution Approach 1:
The patent extracts the sensing and compensation functionality from individual pixel circuits and implements it at the panel level through a sensing device that measures RC delays and a control device that adjusts gate signals accordingly. This approach eliminates the need for complex internal compensation circuits in each pixel while still achieving electrical characteristic uniformity across the display panel.
Data Source
AI summary
A display device receives a feedback signal for a pulse signal supplied to a display panel, senses a pulse width of a scan signal, and changes one or both of a pulse width of the shift clock and a pulse voltage of the shift clock for each screen position of the display panel in response to a pulse width of the feedback signal.