OLED Display Compensation for Horizontal Line Luminance
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Solution Overview
Problem
In OLED display apparatuses, the process differential and deterioration of driving transistors lead to luminance deviations between pixels, causing visible horizontal lines during external compensation, which affects the display quality, especially at low gray scales.
Innovation Solution
A display apparatus and method that converts input image data into compensation image data using a calculated compensation value, outputting a compensation data voltage to data lines before and after sensing for external compensation, thereby maintaining luminance consistency across horizontal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing for external compensation is performed during vertical blank time, then threshold voltage and mobility characteristics can be corrected, but a visible dark horizontal line appears on the display
Solution Approach 1:
The patent applies preliminary action by outputting a compensation data voltage to the data line before the sensing operation begins. This pre-charges the OLEDs along the horizontal line, ensuring they are ready to emit light immediately when the sensing period ends, thereby preventing the dark line phenomenon while maintaining accurate threshold voltage measurement capability
2Adaptability or versatility
If sensing is performed on a horizontal line, then external compensation can be achieved, but no image is displayed during the sensing period causing luminance deviation
Solution Approach 1:
The patent applies preliminary anti-action by counteracting the expected luminance drop before it occurs. By providing a compensation data voltage that charges the OLEDs prior to sensing, the system pre-compensates for the upcoming non-emission period, ensuring luminance consistency across horizontal lines while maintaining external compensation functionality
3Measurement precision
If anode charging period is extended for low gray scale pixels, then threshold voltage compensation can be performed, but non-emission area is enlarged making the horizontal line more visible
Solution Approach 1:
The patent applies preliminary action by charging the OLED anodes with a compensation data voltage before the sensing period begins. This allows the threshold voltage compensation to be performed accurately while minimizing the non-emission area, as the OLEDs are already charged and ready to emit light immediately when sensing completes, preventing the horizontal line from becoming visible
Data Source
AI summary
The present application relates to a display apparatus having a panel including sub-pixels, data lines, and horizontal lines; a sensing circuit to collect sensing data by sensing for external compensation in the horizontal lines; a calculator to determine a characteristic change of each of the sub-pixels using the sensing data to calculate an external compensation value; a data aligner to receive input image data, and when the input image data corresponds to a horizontal line where the sensing is performed, to convert the input image data into compensation image data based on a compensation value; and a data driver to output a compensation data voltage corresponding to the compensation image data to a data line corresponding to the sensed horizontal line before and after the sensing is performed, and output a sensing data voltage to the data line while the sensing is performed.