Stacked OLED Subpixel Circuit for Threshold Voltage Compensation
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Solution Overview
Problem
Current OLED display units face challenges in achieving uniform brightness due to uneven threshold voltage in driving transistors, leading to reduced pixel size and display effectiveness, as increasing the number of TFTs and capacitors to compensate for this issue limits pixel size and display quality.
Innovation Solution
The implementation of a stacked OLED display unit structure with subpixel units of different colors, each connected to separate pixel circuits and controlled by selector switches, allowing for independent control of light emission and improved gray-scale display capabilities, thereby compensating for threshold voltage unevenness and enhancing display effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of TFTs and capacitors is increased to compensate for threshold voltage unevenness, then display uniformity is improved, but pixel size is reduced and device complexity increases
Solution Approach 1:
The pixel circuit is segmented into multiple functional blocks: a driving transistor for current control, a switching transistor for signal input, a compensation transistor for threshold voltage correction, and a capacitor for charge storage. This segmentation allows each component to perform a specific function, achieving display uniformity without requiring excessive total components
Solution Approach 2:
The compensation transistor performs preliminary action by pre-compensating for threshold voltage unevenness during the compensation phase before the display phase. This preliminary compensation ensures that the driving transistor operates with corrected threshold values, achieving uniform display without needing additional correction components during operation
2Manufacturing precision
If the number of TFTs and capacitors is increased to compensate for threshold voltage unevenness, then display uniformity is improved, but pixel size is reduced
Solution Approach 1:
The invention changes the operational parameters of existing components rather than adding more components. By adjusting the timing phases (compensation phase, display phase, reset phase) and utilizing the electrical characteristics of the compensation transistor, the system achieves threshold voltage compensation while maintaining compact pixel size
Solution Approach 2:
The compensation transistor serves multiple functions: it compensates for threshold voltage unevenness, controls the compensation charge transfer, and participates in the reset operation. This multi-functionality allows a single component to address multiple requirements, avoiding the need for separate dedicated components for each function
Data Source
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AI summary
An organic light-emitting diode display unit, a driving method thereof and a display device are disclosed. At least part of pixel units (11) are pixel units (11) each with a stacked structure; each pixel unit (11) with the stacked structure includes two adjacent subpixel unit stacked groups (110); and each subpixel unit stacked group (110) includes at least two subpixel units (111) which have different emitting colors and are stacked and insulated from each other. During display of different image frames, each subpixel unit stacked group (110) in each pixel unit (11) with the stacked structure can display gray-scale effect of at least two colors based on applied signals. Compared with an approach that each subpixel unit can only display gray-scale effect of only one color for different image frames, the display effect can be improved.