OLED Display Emission Time Control for Low Brightness Spots
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Solution Overview
Problem
Conventional organic light emitting displays suffer from display quality issues in the low brightness region due to incomplete compensation of threshold voltages of driving transistors, resulting in observable spots.
Innovation Solution
An organic light emitting display system that includes a converter to generate brightness values, a timing controller to extract emission time and gamma values, and a gamma voltage generator to control emission times and voltages, reducing emission times at lower brightness levels and adjusting gamma values to stabilize threshold voltages and improve display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional organic light emitting display compensates for threshold voltages of driving transistors, then display quality should be improved, but in low brightness region the threshold voltages are not completely compensated resulting in observable spots
Solution Approach 1:
The display operation is segmented into different brightness regions (high brightness and low brightness). Different emission time control strategies are applied to each region: longer emission times for high brightness to ensure threshold voltage compensation, and shorter emission times for low brightness to prevent spot observation. This segmentation resolves the contradiction by allowing region-specific optimization.
Solution Approach 2:
The emission time of pixels is made dynamic rather than fixed. The emission time is adjusted based on the brightness level: extended for high brightness regions to complete threshold voltage compensation, and reduced for low brightness regions to prevent spot visibility. This dynamic adjustment resolves the contradiction between complete compensation and spot prevention.
2Reliability
If emission times are extended to compensate threshold voltages, then threshold voltage compensation is improved, but display quality in low brightness region deteriorates due to spot observation
Solution Approach 1:
Different emission time durations are applied to different local regions based on brightness requirements. High brightness regions receive longer emission times for complete threshold voltage compensation, while low brightness regions receive shorter emission times to avoid spot observation. This local quality differentiation resolves the contradiction between compensation completeness and display quality.
Solution Approach 2:
The emission time parameter is changed dynamically based on brightness level. For high brightness, emission time is extended to ensure threshold voltage compensation. For low brightness, emission time is reduced to prevent spot visibility. This parameter change strategy resolves the contradiction by adapting the same parameter (emission time) to different operational conditions.
3Reliability
If current supply is increased to improve threshold voltage compensation, then compensation completeness is improved, but power consumption increases and lifespan decreases
Solution Approach 1:
The display uses periodic emission control where pixels are activated for specific emission time periods. By controlling the duration of these periodic emission events rather than continuous high current supply, the system achieves threshold voltage compensation while reducing overall power consumption. This periodic action resolves the contradiction between compensation completeness and energy efficiency.
Solution Approach 2:
The threshold voltage compensation is achieved through continuous emission time adjustment across different brightness regions rather than through increased current. By maintaining useful emission action at optimized durations for each region, the system achieves complete compensation without excessive power consumption or reduced lifespan.
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 emission times and increases gamma voltages in the low brightness region, stabilizing threshold voltages and enhancing display quality without increasing overall current supply, thus preventing spots and maintaining the lifespan and power efficiency of the display.
Implementation Method 1
The organic light emitting display display images using organic light emitting diodes (OLED) that generate light by re-combination of electrons and holes
Data Source
AI summary
There is provided an organic light emitting display capable of improving the display quality of a low brightness region. The organic light emitting display includes pixels positioned at intersections of scan lines, emission control lines, and data lines, a converter for receiving data to generate brightness values, a timing controller for extracting emission time values and gamma values to correspond to the brightness values, an emission control line driver for supplying emission control signals to the emission control lines so that emission times of the pixels are controlled to correspond to the emission time values, and a gamma voltage generator for generating gamma voltages corresponding to the gamma values.