OLED Dithering Algorithm for Low Grayscale Stain Reduction
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Solution Overview
Problem
Organic light emitting displays face challenges in finely controlling current driving diodes, particularly in low grayscale ranges, leading to low grayscale stains due to the sensitivity of diodes in this range.
Innovation Solution
An organic light emitting display apparatus employs a comparator to compare image data with critical grayscale values, using a dithering algorithm to determine corrected image data based on pixel position and image frame order, thereby reducing current differences and minimizing low grayscale stains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If direct current control is used for low grayscale display, then the display structure remains simple, but low grayscale stains occur due to difficulty in finely controlling current
Solution Approach 1:
The grayscale control is segmented into multiple critical thresholds (first critical grayscale value, second critical grayscale value, etc.). The display apparatus divides the grayscale range into multiple zones, each handled by different control strategies. This segmentation allows precise control at low grayscale levels while maintaining simplicity for higher grayscale levels.
Solution Approach 2:
The patent changes the control parameter from direct current magnitude to grayscale threshold comparison. By comparing input grayscale values against predetermined critical thresholds and applying dithering algorithms selectively, the system achieves fine current control without directly manipulating small current values, thus avoiding low grayscale stains.
2Manufacturing precision
If dithering algorithm is applied to all grayscale values, then current control precision improves, but flickering increases and processing complexity rises
Solution Approach 1:
The dithering algorithm is applied locally only to specific grayscale ranges (between first and second critical grayscale values) where low grayscale stains occur, rather than uniformly across all grayscale values. This localized application maintains current control precision where needed while avoiding flickering in other ranges.
Solution Approach 2:
Instead of applying dithering to all grayscale values (excessive action), the patent applies it partially only to the critical low grayscale range where it is most needed. This partial application suffices to eliminate stains without introducing unnecessary flickering or processing overhead elsewhere.
3Manufacturing precision
If multiple critical grayscale values are used for correction, then low grayscale stain reduction improves, but processing time and complexity increase
Solution Approach 1:
The critical grayscale values are predetermined and stored in advance. During operation, the system only needs to compare input grayscale values against these pre-established thresholds and apply corresponding corrections, rather than calculating optimal grayscale values in real-time. This preliminary preparation significantly reduces processing time while maintaining high correction accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces low grayscale stains and improves current control, enhancing the display's ability to handle low grayscale images without significant current variation, thus reducing flickering and improving image quality.
Implementation Method 1
images are generated based on light emitted from organic light emitting diodes. Each diode emits light based on the recombination of electrons and holes in an emission layer. The amount of light emitted varies based on an applied current.
Data Source
AI summary
An organic light emitting display apparatus includes a first data line, a comparator, and a data generator. The first data line is connected to a first pixel. The comparator compares first image data of input image data to at least one of a first critical grayscale value or a second critical grayscale value, where the first image data corresponds to the first pixel. The data generator determines the first critical grayscale value or the second critical grayscale value as first corrected image data when the first image data is equal to or greater than the first critical grayscale value but lower than the second critical grayscale value.