AMOLED Brightness Stabilization via Variable Gamma Control
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Solution Overview
Problem
Conventional active matrix organic light emitting displays (AMOLEDs) experience unstable brightness initially, leading to rapid increase and then reduction, resulting in short lifespan and difficulty in commercialization due to damage from continuous driving.
Innovation Solution
A light emitting display system comprising a pixel circuit unit, data driver, scan driver, gamma correcting unit, and timing controller that supplies a variable gamma control signal to adjust the data signal magnitude based on brightness characteristics from the start of operation, stabilizing brightness over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional AMOLED is driven continuously, then brightness can be maintained initially, but the lifespan is rapidly reduced due to damage to TFT and organic light emitting layers
Solution Approach 1:
The patent applies preliminary action by implementing a warm-up period before normal display operation. During this warm-up period, the AMOLED is driven at reduced brightness or with test patterns to gradually stabilize the TFT characteristics and organic light emitting layers, preventing immediate damage from full-power operation and extending overall lifespan
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the driving conditions of the AMOLED based on operational stage. The system transitions from a protective warm-up mode with controlled brightness to normal operation mode, adapting the driving parameters to the current state of the display components to optimize both brightness maintenance and lifespan
2Illumination intensity
If conventional AMOLED is initially driven, then brightness rapidly increases, but then reduces over time leading to unstable display
Solution Approach 1:
The patent applies preliminary action by performing a warm-up sequence before normal operation to pre-stabilize the brightness characteristics. This preliminary driving at controlled conditions allows the organic light emitting layers and TFTs to reach their stable operational state, preventing the initial rapid brightness increase and subsequent reduction
Solution Approach 2:
The patent implements feedback by monitoring the brightness output during the warm-up period and adjusting driving parameters accordingly. This feedback mechanism allows the system to detect and compensate for brightness variations in real-time, ensuring stable and uniform brightness throughout operation
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 system achieves stable and uniform brightness over extended operation, extending the lifespan of the AMOLED by controlling data signal magnitude according to the brightness characteristics, preventing damage to TFTs and organic light emitting layers.
Implementation Method 1
supply holes and electrons to the organic light emitting layers 38 through the pixel electrode 36 and the cathode electrode 40 so that the holes and the electrons are re-combined with each other to emit light
Data Source
AI summary
A light emitting display is provided. The light emitting display comprises a pixel circuit unit comprising a plurality of pixels that display an image; a data driver that supplies a data signal to the pixel circuit unit; a scan driver that supplies a scan signal to the pixel circuit unit; a gamma correcting unit that supplies a gamma value to the data driver to control the magnitude of the data signal; and a timing controller that applies control signals to the data driver and the scan driver and that supplies a variable gamma control signal that controls the gamma correcting unit to supply the gamma value that changes according to the data driving time.