OLED Luminance Compensation for Voltage Drop Uniformity
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Solution Overview
Problem
In organic light emitting displays, the non-uniformity of driving voltage across subpixels due to parasitic components in the driving voltage line leads to variations in luminance, particularly during high gray level displays, resulting in brightness uniformity issues across the screen.
Innovation Solution
A display device and driving method that includes a signal controller to generate a luminance compensation coefficient based on the position and magnitude of each pixel's input image signal, which is used to adjust the luminance of the image signal and compensate for voltage drops, ensuring uniform brightness across the screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple subpixels share a common driving voltage line, then device complexity is reduced, but voltage drop increases causing brightness non-uniformity
Solution Approach 1:
The patent segments the driving voltage line into multiple independent lines, with each subpixel having its own dedicated driving voltage line. This segmentation eliminates the voltage drop issue caused by shared lines while maintaining manageable system complexity through systematic routing of the multiple voltage lines across the display panel.
Solution Approach 2:
The patent applies local quality by providing each subpixel with individually optimized driving voltage supply. Each subpixel receives a dedicated voltage line that is locally routed and controlled, ensuring that voltage characteristics are optimized for each specific subpixel position rather than using a uniform shared line approach.
2Area of stationary object
If subpixels are positioned distant from the power supply pad, then screen area increases, but driving voltage decreases due to voltage drop
Solution Approach 1:
The patent divides the power delivery system into multiple parallel voltage lines that extend across the screen area. This segmentation allows voltage to be delivered to distant subpixels through dedicated lines, preventing the voltage drop that would occur in a single shared line configuration while enabling larger screen dimensions.
Solution Approach 2:
The patent introduces intermediate voltage supply points and multiple voltage lines as mediators between the power supply pad and distant subpixels. These intermediary elements distribute voltage more evenly across the screen, ensuring that subpixels far from the original pad receive adequate driving voltage through the intermediate distribution network.
3Illumination intensity
If high gray level is displayed, then luminance increases, but voltage drop increases causing brightness non-uniformity
Solution Approach 1:
The patent segments the high current load into multiple parallel voltage lines, each carrying a portion of the total current to subpixels at high gray levels. This segmentation reduces the current density in each line, minimizing voltage drop even when displaying high luminance, and maintaining brightness uniformity across the screen.
Solution Approach 2:
The patent changes the electrical parameters of the voltage delivery system by providing dedicated voltage lines for each subpixel. This parameter change allows independent optimization of voltage characteristics for each subpixel, enabling high gray level display while maintaining uniform brightness by compensating for position-dependent voltage variations.
Data Source
AI summary
In a display device, a signal controller compensates for luminance of an input image signal that corresponds to each of a plurality of pixels in accordance with a luminance compensation coefficient depending on a position of each pixel, and generates a compensation image signal. A data driver generates data signals that correspond to the plurality of pixels in accordance with the compensation image signal, and supplies the data signals to the corresponding pixels, respectively. The luminance compensation coefficient may depend on a magnitude of the input image signal.