Driving Controller for OLED Mura Reduction via Adaptive Dithering
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Solution Overview
Problem
Organic light emitting display devices face challenges in controlling fine variations in current flow, leading to low-gray level Mura (blemishes) due to difficulty in managing current amounts, especially during low-gray level image display.
Innovation Solution
An electronic device with a driving controller that includes a minimum emission gray level determining unit, pattern determining unit, driving frequency sensing unit, and data compensation unit to determine gray levels, apply dither patterns, and adjust driving frequencies, compensating image data based on these factors to stabilize current flow and reduce Mura.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the organic light emitting diode operates at low gray levels, then power consumption is reduced, but the emission level varies sharply causing low-gray level Mura
Solution Approach 1:
The patent applies dithering patterns to image data before display to pre-distribute luminance variations across multiple pixels. This preliminary action prevents sharp emission level changes at low gray levels by spreading the luminance across a pattern, thereby reducing low-gray level Mura while maintaining power efficiency.
Solution Approach 2:
The patent modifies the image data parameters by applying different dithering patterns based on gray level thresholds. When gray levels are below a threshold, dithering is applied to alter the luminance distribution parameters, preventing sharp emission variations and reducing Mura effects while preserving low power consumption benefits.
2Manufacturing precision
If dithering is applied to low gray level image data, then low-gray level Mura is reduced, but image processing complexity increases
Solution Approach 1:
The patent applies dithering selectively only to image data with gray levels below a predetermined threshold. This local approach processes only the problematic low-gray-level regions, improving display quality where needed while avoiding unnecessary processing of higher gray levels, thus limiting the increase in processing complexity.
Solution Approach 2:
The patent applies partial dithering by selecting specific dithering patterns based on gray level conditions rather than applying uniform processing to all image data. This partial action approach reduces processing complexity compared to full-frame dithering while still effectively addressing low-gray-level Mura issues.
3Loss of energy
If variable driving frequency mode is used, then power consumption is optimized, but low-gray level Mura may occur due to insufficient effective charging time
Solution Approach 1:
The patent incorporates a driving frequency sensing unit that detects the driving frequency and provides feedback to the data compensation unit. Based on this feedback, the system adjusts the dithering pattern selection and compensation parameters to ensure adequate effective charging time even in variable driving frequency mode, preventing low-gray-level Mura while maintaining power optimization.
Solution Approach 2:
The patent dynamically adapts the dithering pattern and compensation parameters based on the detected driving frequency. When operating in variable driving frequency mode, the system modifies its processing approach in real-time to account for changes in effective charging time, ensuring stable current flow and preventing Mura while preserving energy efficiency.
Data Source
AI summary
An electronic device is disclosed that includes a display panel, a data driving circuit, a scan driving circuit, and a driving controller. The driving controller generates image data based on a received image signal. The driving controller includes a minimum emission gray level determining unit that determines a gray level of the image signal, a pattern determining unit that determines a dither pattern of the image signal, a driving frequency sensing unit that determines a driving frequency of the image signal, and a data compensation unit that compensates for the image data based on the gray level and at least one of the dither pattern and the driving frequency.