OLED Initialization Voltage Prevents Flickering
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Solution Overview
Problem
Organic light emitting diodes (OLEDs) in display devices are prone to flickering and damage due to high voltage differences during initial driving.
Innovation Solution
A light emitting display device with an organic light emitting diode connected to a capacitor and a driving transistor, where an initialization voltage is applied to prevent light emission and avoid irreversible damage, set between the threshold and breakdown voltages of the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a high voltage difference is applied to the OLED during initial driving, then the OLED can be driven to emit light, but the OLED suffers from flickering and damage
Solution Approach 1:
The patent applies an initialization voltage to the drain node of the subpixel before normal driving operations begin. This preliminary action sets the node to a known voltage state, preventing the high voltage difference that causes flickering and damage during initial driving, while still allowing the OLED to emit light when properly driven
2Reliability
If the initialization voltage is set above the threshold voltage, then the OLED can be initialized properly, but the OLED emits light during initialization which is unwanted
Solution Approach 1:
The patent carefully selects the initialization voltage parameter to be below the threshold voltage of the OLED. This parameter change ensures that the voltage is sufficient to initialize the drain node and prevent flickering, while remaining low enough to prevent the OLED from emitting light during the initialization process
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 solution effectively eliminates OLED flickering and damage by initializing the drain node of a subpixel with a voltage that prevents light emission, thereby safeguarding the OLED during initial driving.
Implementation Method 1
an electroluminescent layer comprising an organic compound emits visible light
Implementation Method 2
a capacitor configured to store a data voltage
Data Source
AI summary
A light emitting display device is disclosed that includes an organic light emitting diode having an anode electrode connected to a first power line and a cathode electrode, a capacitor configured to store a data voltage and having a first electrode and a second electrode, and a driving transistor having a first electrode connected to the cathode electrode of the organic light emitting diode, a gate electrode connected to the first electrode of the capacitor, and a second electrode connected to the second electrode of the capacitor and a second power line. The driving transistor applies an initialization voltage to a node connected to the cathode electrode of the organic light emitting diode and the first electrode of the driving transistor.