AMOLED Pixel Driver Power Conservation via Dynamic Voltage Scaling
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Solution Overview
Problem
Active matrix organic light emitting diode (AMOLED) displays experience higher power consumption at peak brightness compared to active matrix liquid crystal displays (AMLCDs), making them less suitable for applications like email and web surfing, due to the inefficiencies in thin film drive transistors and OLEDs.
Innovation Solution
A current-biased, voltage-programmed circuit for AMOLED displays that adjusts the supply voltage based on the content of the display segment, reducing power consumption by setting the voltage to the minimum required for the current content and lowering it when fewer pixels need higher voltage, thereby conserving energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a higher supply voltage is applied to achieve peak brightness in AMOLED displays, then the brightness level is improved, but the power consumption increases significantly
Solution Approach 1:
The supply voltage is made dynamic rather than fixed, allowing it to adjust automatically based on the actual brightness requirements of different display segments. This enables the system to operate at lower voltages when full brightness is not needed, reducing power consumption while maintaining peak brightness capability when required.
Solution Approach 2:
Different segments of the display are allowed to operate at different voltage levels based on their specific content requirements. This local optimization ensures that only the necessary portions of the display consume high power, while other areas operate efficiently at lower voltages.
2Stability of the object's composition
If a fixed high supply voltage is used to ensure all pixels can achieve required brightness, then the brightness uniformity is improved, but the overall power consumption increases
Solution Approach 1:
The system dynamically adjusts supply voltage levels based on real-time monitoring of display content and actual brightness requirements, replacing the fixed high voltage approach with adaptive voltage control that maintains uniformity only where needed.
Solution Approach 2:
The system monitors display content and brightness requirements, using this feedback information to automatically adjust supply voltage levels. This closed-loop control ensures brightness uniformity is maintained through intelligent adjustment rather than blanket high voltage application.
3Use of energy by moving object
If the supply voltage is reduced to conserve power, then the power consumption is improved, but the brightness level and luminescence quality deteriorate
Solution Approach 1:
The supply voltage is dynamically optimized to match actual display needs, preventing both excessive power consumption and unnecessary brightness reduction. The system adapts voltage levels in real-time to maintain quality where required while saving power where possible.
Solution Approach 2:
The system changes the supply voltage parameter adaptively based on display content analysis, transitioning between different voltage levels to optimize the trade-off between power consumption and brightness quality for different operating conditions.
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
This approach reduces power consumption by up to 40% in high brightness applications while maintaining necessary luminescence, extending the lifespan of drive transistors and improving power efficiency compared to conventional AMOLED displays.
Implementation Method 1
An organic light emitting device emitting light has a brightness level as a function of current flow
Data Source
AI summary
A system is provided for conserving energy in an AMOLED display having pixels that include a drive transistor and an organic light emitting device, and an adjustable source of a supply voltage for the drive transistor. The system monitors the content of a selected segment of the display, sets the supply voltage to the minimum supply voltage required for the current content of the selected segment of the display, determines whether the number of pixels requiring a supply voltage larger than the set value is greater than a predetermined threshold number, and, when the answer is negative, reduces the supply voltage by a predetermined step amount.