Display Panel Pixel Compensation for Luminance Uniformity
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Solution Overview
Problem
Display devices, particularly OLEDs, suffer from luminance non-uniformity due to characteristic value changes or deviations in transistors and OLEDs across subpixels, leading to degraded display quality.
Innovation Solution
A pixel compensation technique is implemented, where a sensing line connected to each subpixel senses characteristic values, and an ADC converts these values into digital data to adjust the data provided to subpixels, compensating for transistor changes and preventing luminance non-uniformity, with the timing controller controlling the data driving and gate driving units to apply appropriate voltages during blank times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixel compensation technique is implemented to sense and adjust data for each subpixel, then luminance non-uniformity is reduced, but device complexity increases due to additional sensing lines and ADC components
Solution Approach 1:
The sensing line serves multiple functions: it acts as both a gate line for driving subpixels and a sensing line for measuring transistor characteristic values. This multi-functionality eliminates the need for separate dedicated sensing lines, reducing structural complexity while maintaining pixel compensation capability
Solution Approach 2:
The system uses its existing gate lines and data lines to perform sensing operations without requiring entirely separate dedicated sensing circuits. The gate driving unit and data driving unit are utilized to apply sensing voltages and read sensing results, making the existing infrastructure serve dual purposes
2Reliability
If recovery data is applied to reset transistors during blank time, then transistor characteristic deviations are corrected, but charge accumulation occurs on the first gate line of the next frame causing brightness defects
Solution Approach 1:
Before applying recovery data to reset transistors, the system pre-charges the first gate line to a specific voltage level during the blank time. This preliminary action counteracts the charge accumulation that would otherwise occur when recovery data is applied, preventing brightness defects on the first gate line of the next display frame
Solution Approach 2:
The first gate line is charged to a predetermined voltage level during the blank time before the actual display frame begins. This preliminary charging ensures that when recovery data is subsequently applied to reset transistors, the gate line maintains proper voltage levels and avoids brightness defects
3Manufacturing precision
If data voltages are output to data lines during blank time with waveforms identical to gate line voltages, then charge characteristics are equalized, but energy consumption increases
Solution Approach 1:
Instead of applying the same charging waveform to all data lines, the system selectively charges only specific data lines that are connected to subpixels requiring reset. The charging operation is localized to areas where it is actually needed, reducing unnecessary energy consumption while maintaining charge characteristic uniformity where required
Data Source
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AI summary
A display device can include a display panel, in which a subpixel including a transistor where data lines and gate lines intersect, is disposed; a gate driving unit that sequentially outputs a gate signal to the gate lines; a data driving unit that outputs a data voltage to the data lines according to the gate signal provided to each gate line, and outputs to the data lines during a blank time before a specific frame, data voltages having an output waveform that is identical to data voltages of at least one gate line of the specific frame; and a timing controller that controls the gate driving unit and the data driving unit, and performs a pixel compensation which changes data provided to each subpixel.