OLED Luminance Restoration via Dynamic Reverse Bias Voltage Control
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Solution Overview
Problem
Conventional methods for restoring decreased luminance in OLEDs using reverse bias voltage often result in excessive voltage application, leading to potential breakdown and require significant computational effort for setting application conditions, failing to extend the life of the OLED effectively.
Innovation Solution
A display apparatus comprising a light emitting element, a capacitor, a driver, memory for storing trap levels associated with use durations, and a controller to apply a reverse bias voltage based on read trap levels, varying the voltage level with use duration and temperature to prevent excessive stress on the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse bias voltage is applied to restore decreased luminance of OLED, then luminance restoration is achieved, but OLED may suffer deterioration or breakdown due to excessive voltage
Solution Approach 1:
The patent applies preliminary action by measuring the forward voltage across the OLED before applying reverse bias voltage, and using this measurement to determine the appropriate reverse bias voltage level. This preliminary measurement allows the system to adapt the reverse bias voltage to the actual state of the OLED, preventing excessive voltage application that could cause deterioration or breakdown.
Solution Approach 2:
The patent implements feedback by continuously monitoring the forward voltage of the OLED and using this information to control the reverse bias voltage application. The control unit adjusts the reverse bias voltage based on the measured forward voltage, creating a closed-loop control system that prevents excessive voltage stress on the OLED while effectively restoring luminance.
2Reliability
If reverse bias voltage is applied at constant level to restore luminance, then luminance restoration is achieved, but enormous calculation is required for setting application conditions
Solution Approach 1:
The patent applies parameter changes by transitioning from a constant reverse bias voltage level to a variable reverse bias voltage level that is dynamically determined based on the measured forward voltage. The control unit calculates the reverse bias voltage as a function of the measured forward voltage, thereby adapting the voltage parameter to the actual OLED state without requiring enormous calculations for setting application 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
Proper restoration of decreased luminance is achieved while extending the life of the OLED by dynamically adjusting the reverse bias voltage based on trap levels and use duration, preventing excessive voltage application and reducing computational load.
Implementation Method 1
a capacitor that stores a charge; a driver that flows the current through the power line to the light emitting element, the current corresponding to the charge stored in the capacitor
Implementation Method 2
remove a charge generated in the light emitting element by application of a reverse bias voltage to the light emitting element
Data Source
AI summary
A display apparatus is provided which optimally restores decreased luminance and extends a life of a light emitting element. The display apparatus includes a memory that stores a plurality of trap levels in association with a plurality of use durations of the light emitting element. An obtainer determines one of the plurality of use durations of the light emitting element. A controller reads, from the memory, one of the plurality of trap levels associated with the one of the plurality of use durations, and removes a charge from the light emitting element by application of a reverse bias voltage having a level associated with the one of the plurality of trap levels. The controller changes the level of the reverse bias voltage which is applied to the light emitting element so that as the one of the plurality of use durations increases, the level of the reverse bias voltage increases.