OLED Luminance Control Circuit for Still Image Burn-In Prevention
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Solution Overview
Problem
Organic light emitting diode (OLED) displays experience deterioration and image burn-in when displaying still images for extended periods, leading to reduced display quality and lifespan due to stress on organic light emitting diodes and thin film transistors.
Innovation Solution
A luminance control circuit that calculates a target luminance gain based on the average luminance of an image signal, gradually reducing the luminance of still images to minimize stress on OLEDs and transistors, using a target luminance gain calculator, output luminance gain calculator, and luminance scaler to adjust the image signal, while also storing previous luminance gains and applying decay weights to smooth luminance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the OLED device displays a still image for a long time, then the image quality is maintained, but the organic light emitting diode or thin film transistor deteriorates causing stain and reduced lifespan
Solution Approach 1:
The system detects still images in advance and applies luminance reduction before deterioration occurs. The still image detection unit identifies static content, and the luminance control circuit proactively reduces brightness to prevent organic material degradation and burn-in, rather than waiting for damage to manifest.
Solution Approach 2:
The invention dynamically changes the luminance parameter of the display based on image content. When still images are detected, the system adjusts the luminance gain coefficient to reduce overall brightness, thereby decreasing stress on organic light emitting diodes and thin film transistors without completely turning off the display.
2Reliability
If the luminance of still images is reduced, then deterioration and burn-in are minimized, but the display quality and user perception may be affected
Solution Approach 1:
The system applies partial luminance reduction rather than complete dimming. By using a luminance gain coefficient that partially reduces brightness (not fully extinguishing the display), the system achieves sufficient stress reduction to prevent deterioration while maintaining acceptable display quality and user perception.
Solution Approach 2:
The luminance reduction is applied proactively when still images are detected, preventing deterioration before it occurs. This preliminary action allows the system to maintain normal brightness for moving images while selectively reducing brightness only when needed, preserving overall display quality.
Data Source
AI summary
A luminance control circuit of a display device includes a target luminance gain calculator calculating a target luminance gain based on an average luminance of a first image signal when the first image signal is determined to be a still image, an output luminance gain calculator calculating an output luminance gain based on a previous output luminance gain of a previous frame and the target luminance gain of a present frame, and a luminance scaler outputting a second image signal obtained by changing a luminance of the first image signal based on the output luminance gain.