Gate Driver Q Node Charging for OLED Sensing Accuracy
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Solution Overview
Problem
In organic light emitting display devices, the charge level for the Q node during sensing driving is insufficient due to a longer charge path and shorter time, leading to inaccurate sensing of driving characteristics and reduced compensation performance.
Innovation Solution
A gate driver with a pixel line selecting unit that charges a first node with a gate-on voltage during display driving and a second node with a higher potential power supply voltage during sensing driving, ensuring the Q node is sufficiently charged for accurate sensing, and an inverter unit that manages power supply voltages to maintain the charged state during sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gate driver operates a specific stage during sensing driving to output a gate signal, then sensing of pixel driving characteristics can be performed, but the charge level for the Q node becomes insufficient due to the longer charge path and shorter time
Solution Approach 1:
The patent applies preliminary action by charging the Q node with a gate-on voltage during display driving before the sensing driving occurs. This pre-charging ensures that when sensing driving starts, the Q node already has sufficient charge level despite the longer charge path and shorter available time during sensing operation.
Solution Approach 2:
The patent implements dynamics by making the charge path configurable - during display driving, the pixel line selecting unit charges the Q node through a first charge path, while during sensing driving, it charges through a second charge path. This dynamic switching of charge paths allows optimization for each operating mode, ensuring sufficient charge level during sensing despite time constraints.
2Reliability
If the Q node charge path is made longer to ensure proper charging, then the gate signal can be properly output, but the time required for charging increases which is problematic during sensing driving
Solution Approach 1:
The patent uses preliminary action by completing the Q node charging during display driving before sensing driving begins. This ensures the gate signal can be properly output during sensing without requiring additional charging time during the sensing operation itself.
Solution Approach 2:
The patent segments the charging operation from the sensing operation - charging occurs during display driving while sensing occurs during vertical blanking period. This segmentation allows the longer charge path to be used during display driving without impacting sensing time, as the charging and sensing are performed in separate time segments.
Data Source
AI summary
A gate driver has a plurality of stages for outputting a gate signal for image at a time of display driving and outputting a gate signal for sensing at a time of sensing driving that follows the display driving. Each of the stages includes a pixel line selecting unit charging an M node with a first preceding stage carry signal according to a pixel line selection signal of a gate-on voltage during the display driving and charging a Q node with a first high-potential power supply voltage according to a sensing start signal of a gate-on voltage and a charged voltage of the M node during the sensing driving, and an output unit outputting a scan clock of a gate-on voltage as the gate signal for sensing while the Q node maintains a charged state on the sensing driving, wherein the first high-potential power supply voltage is higher at the time of the sensing driving than at the time of the display driving.