OLED Pixel Crosstalk Compensation via Grey Level Offset
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Solution Overview
Problem
OLED displays experience pixel crosstalk due to electrical characteristics, affecting image fidelity, particularly in high refresh rates and low persistence rolling shutter modes, where nearby pixels' current draw impacts voltage and current availability, leading to undesirable artifacts.
Innovation Solution
A system comprising a buffer memory, aggregation engine, offset engine, and compensation engine that calculates grey level totals, determines corresponding offset values from a look-up-table, and adjusts pixel grey levels to compensate for voltage drops across resistive values, mitigating crosstalk by providing compensated pixel grey levels to the OLED display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high refresh rates and low persistence rolling shutter modes are used in OLED displays, then the display can achieve better motion clarity and reduced motion blur, but pixel crosstalk increases due to electrical characteristics causing voltage drops and current load variations
Solution Approach 1:
The system performs preliminary calculation of the sum of grey levels for all pixels before driving the display. Based on this pre-calculated total grey level, the system determines an appropriate compensation value from a lookup table and applies it to adjust individual pixel grey levels before they are driven onto the OLED display. This preliminary action prevents crosstalk artifacts from occurring in the first place.
Solution Approach 2:
The system dynamically changes the grey level parameters of individual pixels based on the total grey level sum. By adjusting pixel intensities according to the overall brightness demand, the system compensates for voltage drops and current load variations that cause crosstalk, while maintaining the high refresh rate operation.
2Manufacturing precision
If pixel intensities are adjusted to compensate for crosstalk, then image fidelity improves, but additional processing steps are required to calculate and apply compensation values
Solution Approach 1:
The display is divided into multiple pixel portions, and the compensation process is segmented into distinct stages: calculating the total grey level sum, looking up the corresponding compensation value from a pre-generated lookup table, and applying the compensation to individual pixels. This segmentation makes the complex compensation process more manageable and efficient.
Solution Approach 2:
The system uses a lookup table that stores pre-calculated compensation values based on total grey level sums. Instead of performing complex real-time calculations, the system copies the appropriate compensation value from the lookup table based on the calculated total grey level, significantly reducing processing complexity while maintaining image fidelity.
3Object-affected harmful factors
If grey level compensation is applied to reduce crosstalk, then visible artifacts are reduced, but the processing time and computational load increase
Solution Approach 1:
The lookup table containing compensation values is pre-generated and stored before display operation. During high-speed display refresh, the system only needs to calculate the total grey level sum and perform a quick lookup, rather than performing complex iterative calculations in real-time. This preliminary preparation dramatically reduces processing time during actual display operation.
Solution Approach 2:
The compensation process is integrated into the periodic display refresh cycle. The total grey level sum is calculated and compensation is applied at each refresh period, synchronizing with the display's natural update rhythm. This periodic approach ensures smooth compensation without adding excessive processing overhead between frames.
Data Source
AI summary
A portion of an image frame of video content is received and a grey level total of the portion of the image frame is calculated. A grey level offset value corresponding to the grey level total is determined. The grey level offset value corresponds to a pixel portion of an Organic Light Emitting Diode (OLED) display that will display the portion of the image frame. Compensated pixel grey levels are generated by adjusting individual pixel grey levels using the grey level offset value. The compensated pixel grey levels are driven onto the pixel portion of the OLED display.