OLED Luminance Control via Emission Time Adjustment
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Solution Overview
Problem
Organic light emitting displays (OLEDs) are often too bright, causing discomfort, especially in low-light conditions, due to their high luminance and lack of effective luminance adjustment methods.
Innovation Solution
A method for driving OLEDs that adjusts luminance by modifying light emission time and current limitation, using lookup tables to control light emission drivers and gamma voltage, with different approaches for luminance values above or below a predetermined threshold of 10 nits, to reduce luminance and prevent glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic light emitting displays operate at high luminance, then brightness and visibility are improved, but comfort and suitability for low-light conditions deteriorate
Solution Approach 1:
The patent implements dynamic luminance control by adjusting the light emission time duration based on ambient light conditions and content requirements. The system dynamically modifies the emission time of OLED pixels to achieve appropriate luminance levels, transitioning from static high luminance operation to adaptive dynamic control that prevents glare while maintaining visibility.
Solution Approach 2:
The patent changes the emission time parameter of OLED pixels to control luminance output. By varying the duration for which pixels emit light within each frame cycle, the system achieves continuous luminance adjustment without requiring physical hardware changes, effectively resolving the contradiction between maintaining brightness and preventing glare.
2Object-affected harmful factors
If luminance is reduced for comfort in low-light conditions, then glare is prevented, but visibility and image quality may deteriorate
Solution Approach 1:
The patent employs periodic light emission control where pixels are activated for specific time intervals within each frame cycle. By controlling the duty cycle of emission (on-time versus off-time within each period), the system maintains average luminance at comfortable levels while preserving peak brightness capability for maintaining image quality and visibility.
Solution Approach 2:
The system dynamically adjusts emission time based on scene requirements, transitioning between longer emission periods for visibility-critical content and shorter periods for glare prevention, thereby maintaining image quality across varying luminance demands.
3Device complexity
If a single luminance adjustment method is used for all luminance levels, then device complexity is reduced, but precision and effectiveness of luminance control deteriorate
Solution Approach 1:
The patent segments the luminance control process into multiple methods based on luminance level ranges. Different control strategies are applied to different luminance segments (e.g., high luminance versus low luminance ranges), allowing precise control for each segment while maintaining overall system manageability through clear segmentation criteria.
Solution Approach 2:
The patent applies different control characteristics to different luminance levels locally. High luminance values receive one type of adjustment treatment while low luminance values receive another, optimizing control precision for each local operating condition rather than applying a uniform control approach across all luminance levels.
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
Effectively reduces OLED luminance to comfortable levels, preventing glare and maintaining image quality, especially in low-light conditions, by dynamically adjusting light emission times and current limits based on input data and lookup tables.
Implementation Method 1
The light is emitted based on a combination of electrons and holes in an active layer. The electrons and holes are injected from respective electrodes, and combine to form excitons that emit light when transitioning to a stable state.
Data Source
AI summary
A method for controlling a display device includes adjusting the luminance value of input data by a first method when the luminance value is greater than or equal to a predetermined number of nits, and adjusting the luminance value by a second method when the luminance value is less than the predetermined number of nits. The first method reduces the luminance value by a first predetermined percentage. The second method adjusts the luminance value to a first value corresponding to a predetermined luminance value set for the predetermined number of nits, and then reduces the first value by a second predetermined percentage different from the first predetermined percentage. The predetermined number of nits may be 2 nits or another number of nits.