OLED Display On-Pixel Ratio Brightness Control
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Solution Overview
Problem
High dynamic range (HDR) images in organic light emitting display devices consume more power due to increased brightness, leading to higher power consumption compared to standard dynamic range (SDR) images.
Innovation Solution
An organic light emitting display device and its driving method that calculate the on-pixel ratio (OPR) of HDR images and adjust the brightness of on-pixels by controlling the power voltage and gamma settings, reducing power consumption by decreasing the high power voltage or increasing the low power voltage when the on-pixel ratio is below a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high dynamic range (HDR) image is displayed with high brightness, then image quality and contrast ratio are improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic brightness adjustment by calculating the on-pixel ratio in real-time and adapting the driving voltage accordingly. The image processor dynamically changes the brightness level based on the calculated OPR, transitioning between high brightness (when OPR is high) and low brightness (when OPR is low) modes, thereby resolving the contradiction between maintaining high brightness for image quality and reducing power consumption.
Solution Approach 2:
The patent changes the driving voltage parameter based on the on-pixel ratio calculation. When OPR is high, the full high power voltage is applied to maintain high brightness. When OPR is low, the driving voltage is reduced to lower brightness levels, thereby maintaining image quality where needed while reducing overall power consumption through parameter adaptation.
2Reliability
If brightness of on-pixels is increased for HDR image, then contrast ratio is improved, but power consumption increases
Solution Approach 1:
The patent applies local quality by maintaining high brightness and contrast ratio only for the necessary portion of the display (on-pixels with OPR > threshold) while reducing brightness for off-pixels or low-OPR regions. This selective application of high brightness preserves contrast ratio where needed while minimizing power consumption in other areas.
Solution Approach 2:
The contrast ratio is dynamically maintained by adjusting brightness based on real-time OPR calculation. The system adapts the brightness level frame-by-frame or line-by-line depending on the OPR, ensuring high contrast ratio is maintained when necessary while reducing power consumption when full brightness is not required.
3Illumination intensity
If high power voltage is continuously applied to pixels, then brightness is maintained, but power consumption increases
Solution Approach 1:
The patent implements periodic recalculation of the on-pixel ratio at specific intervals (frame basis or line basis) to determine when high power voltage is actually needed. Instead of continuous high voltage application, the system periodically assesses the OPR and adjusts voltage levels accordingly, maintaining brightness when necessary while reducing power consumption during low-OPR periods.
Solution Approach 2:
The driving voltage is dynamically adjusted based on real-time OPR calculation rather than being continuously fixed at high level. The system transitions between high voltage and reduced voltage states based on the calculated OPR, thereby maintaining brightness when needed while significantly reducing power consumption during low-OPR conditions.
Data Source
AI summary
An organic light emitting display device includes: a display panel including a plurality of pixels; a power source configured to provide a high power voltage and a low power voltage to the pixels; a data driver configured to provide a data signal to the pixels through data lines; a scan driver configured to provide a scan signal to the pixels through scan lines; a timing controller configured to provide control signals that control the power source, the data driver, and the scan driver; and an image processor configured to receive an HDR image signal by every frame, calculate an on-pixel ratio (OPR) that represents a ratio of a number of the pixels that turn on based on the HDR image signal to the number of all pixels included in the display panel, and control a brightness of the pixels that turn on based on the on-pixel ratio.