AMOLED Common Voltage Control Circuit for Driving Current Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The voltage difference across the terminals of the transistor in active matrix organic light emitting diode (AMOLED) panels increases over time, leading to a decrease in the driving current and unstable picture quality due to the constant voltage difference between the operating voltage and common voltage.
Innovation Solution
A control circuit with a memory unit and voltage control unit that adjusts the common voltage based on the operating time or turn-on frequency of the AMOLED panel, maintaining a constant operating voltage to ensure stable driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the common voltage is kept constant, then the circuit is simple and easy to control, but the voltage difference across the OLED increases over time causing unstable driving current and degraded picture quality
Solution Approach 1:
The patent applies dynamics by making the common voltage adjustable rather than fixed. The control circuit dynamically changes the common voltage based on the operating time of the AMOLED panel, allowing the system to adapt to aging effects and maintain stable driving current throughout the panel's operational life.
Solution Approach 2:
The patent implements feedback through the control circuit that monitors the operating time of the AMOLED panel and uses this information to adjust the common voltage. This closed-loop control ensures that the driving current remains stable by compensating for voltage changes that occur over time.
2Reliability
If the common voltage is adjusted according to operating time, then the driving current remains stable and picture quality is maintained, but the control circuit becomes more complex
Solution Approach 1:
The patent applies parameter changes by adjusting the common voltage parameter based on the operating time. The control circuit modifies the voltage parameter dynamically to compensate for aging effects, thereby maintaining stable driving current and picture quality throughout the panel's operational life.
3Power
If the voltage difference across the OLED is allowed to increase, then the transistor can drive the OLED with higher current initially, but the voltage difference between transistor terminals decreases continuously eventually causing unstable operation
Solution Approach 1:
The patent applies preliminary action by proactively adjusting the common voltage based on predicted aging effects. The control circuit anticipates the voltage changes that will occur over time and pre-adjusts the common voltage to compensate for these changes, preventing unstable operation before it occurs.
Data Source
AI summary
A control circuit for use in an active matrix organic light emitting diode (AMOLED) panel comprising a memory unit and a voltage control unit is provided. The operating time of the AMOLED panel is counted and saved by the memory unit. According to the memory unit's information, the voltage control unit decides a common voltage. The purpose of the present invention is to reduce the common voltage when the turn-on time of the AMOLED panel is increased so that the increase in the voltage difference between the two terminals of an organic light emitting diode (OLED) of the AMOLED panel may be compensated. Thus, the present invention may provide a stable driving current for the OLED and a stable picture definition for the AMOLED panel.