QLED Driving Waveform for Trapped Charge and Afterimage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Trapped holes and electrons in the light-emitting layer of a quantum dot light-emitting diode (QLED) lead to reduced display quality and lifespan due to afterimage stains and inefficient light emission.
Innovation Solution
Applying alternating-current (AC) and direct-current (DC) powers with specific voltage levels and durations to the QLED, effectively removing trapped charges and enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct-current power is applied to the quantum dot light-emitting diode, then the device operates continuously with stable electrical characteristics, but trapped charges accumulate in the light-emitting layer causing afterimage stains and reduced lifespan
Solution Approach 1:
The patent applies alternating-current power with a specific period to the quantum dot light-emitting diode. The AC power alternates between forward and reverse directions, creating periodic electrical stress that prevents charge accumulation. The period is specifically designed to allow trapped charges to be released before they can cause afterimage stains, while maintaining continuous operation of the display device.
Solution Approach 2:
The patent changes the electrical parameters by using AC power with specific voltage levels and time durations. The forward voltage level, reverse voltage level, and duration of each state are carefully controlled to optimize charge release while maintaining device operation. This parameter optimization resolves the contradiction between continuous operation and charge accumulation.
2Reliability
If alternating-current power with three voltage levels is applied to remove trapped charges, then afterimage stains are prevented and lifespan is extended, but the power control complexity increases
Solution Approach 1:
The AC power signal follows a periodic waveform with three distinct voltage levels that repeats at a fixed period. This periodic structure simplifies the control system compared to arbitrary waveforms, as the same sequence of voltage levels is applied repeatedly. The period and voltage levels are optimized to effectively release trapped charges while maintaining manageable control complexity.
Solution Approach 2:
The patent uses three specific voltage levels (forward, reverse, and intermediate) with optimized durations for each level. This discrete parameter approach simplifies the power control system compared to continuous variable control, while still achieving effective charge release. The specific voltage levels and time durations are carefully selected to balance effectiveness with control simplicity.
Data Source
AI summary
A display panel includes a pixel including a quantum dot light-emitting diode. A first power and a second power are applied to the pixel. One of the first power and the second power is an alternating-current power and a remaining one of the first power and the second power is a direct-current power. The alternating-current power which is the one of the first power and the second power has three different voltage levels.