OLED Driving Voltage Generator Threshold Compensation
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Solution Overview
Problem
Organic light emitting displays (OLEDs) experience brightness reduction due to degradation of switching and driving transistors, leading to a change in threshold voltage over time, which affects the uniformity of current flow to the OLED, resulting in decreased lifespan and non-uniform brightness.
Innovation Solution
A method and system for an OLED that involves a driving voltage generator to sense and adjust the gate high voltage based on the threshold voltage and operation time, generating a level-controlled gate signal to maintain optimal current flow and prevent degradation, comprising a voltage controller that senses threshold voltages and adjusts the gate high voltage accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a conventional OLED display is operated over time, then the display provides initial brightness and functionality, but the threshold voltage of switching and driving transistors changes due to degradation, causing brightness reduction and non-uniform current flow
Solution Approach 1:
The patent implements a feedback mechanism by sensing the threshold voltage of switching and driving transistors at different operation times and using this sensed information to adjust the gate high voltage level. This closed-loop control compensates for transistor degradation, maintaining uniform brightness throughout the OLED's operational lifespan.
Solution Approach 2:
The patent changes the gate high voltage parameter dynamically based on sensed threshold voltage values and operation time. By adjusting this voltage parameter, the system compensates for transistor degradation effects, maintaining consistent current flow and brightness uniformity over the display's operational life.
2Duration of action of stationary object
If the threshold voltage changes due to transistor degradation, then the OLED operates for extended periods, but the current flow to pixels becomes non-uniform, resulting in brightness reduction
Solution Approach 1:
The sensing unit continuously monitors threshold voltage changes in switching and driving transistors during operation. This feedback information is used by the voltage controller to adjust gate high voltage, ensuring uniform current distribution to all pixels even as transistors degrade over extended operation periods.
Solution Approach 2:
The patent performs preliminary sensing of threshold voltage at multiple operation time points and proactively adjusts the gate high voltage before significant brightness non-uniformity occurs. This preventive approach maintains current flow uniformity throughout the OLED's operational life.
Data Source
AI summary
Disclosed are an organic light emitting display capable of preventing lowering of brightness and prolonging its a lifespan, and a driving method thereof. The organic light emitting display controls a level of a gate signal, by outputting a gate high voltage after controlling a level of the gate high voltage, according to a level of a threshold voltage sensed from each pixel of a display panel.