Shift Register Pull-Up Node Potential Maintenance Circuit
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Solution Overview
Problem
In a-Si Full-in-Cell display products using the LH Blanking touch driving mode, it is difficult to maintain a stable potential at the pull-up node of the shift register unit between display time periods, leading to potential differences between gate electrode rows and resulting in stripes, especially at high temperatures.
Innovation Solution
A shift register unit with a pull-up node state maintenance circuitry that controls the connection to a control voltage input end based on the potential at the pull-up node, including transistors and capacitors to maintain the potential, and a method for driving the shift register unit by applying high and low voltages during touch and display time periods to prevent current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a blanking time period is inserted between two adjacent row scanning operations for touch driving, then touch function can be integrated into LCD panel, but the potential at the pull-up node becomes unstable and stripes occur
Solution Approach 1:
The patent applies preliminary action by pre-charging the pull-up node to a high potential level before the blanking time period begins. The pull-up control transistor is turned on in advance to charge the pull-up node through the first electrode connected to the high potential power supply, ensuring the node maintains stable high potential throughout the blanking period when touch operations occur.
Solution Approach 2:
The patent introduces an intermediary element - the pull-up control transistor - that mediates between the high potential power supply and the pull-up node. This transistor acts as a controlled switch that connects or disconnects the high potential supply to the pull-up node based on timing signals, thereby maintaining potential stability during blanking periods while enabling touch functionality.
2Device complexity
If the pull-up node potential is not maintained during blanking time period, then circuit operation is simple, but current leakage occurs and display effect deteriorates
Solution Approach 1:
The pull-up control transistor is activated in advance before the blanking time period to pre-charge the pull-up node to high potential. This preliminary charging action ensures that when the blanking period begins, the pull-up node already has sufficient potential to prevent current leakage and maintain stable operation throughout the touch driving interval.
Solution Approach 2:
The patent implements feedback control where the pull-up control transistor's on/off state is determined by timing signals that respond to the display driving cycle. The transistor is turned on during blanking periods when potential maintenance is needed and turned off during normal scanning periods, creating a feedback-based control mechanism that maintains reliability without requiring continuous complex operation.
Data Source
AI summary
The present disclosure provides a shift register unit, a driving method thereof, a gate driving circuit and a display device. The shift register unit includes a pull-up node state maintenance circuitry connected to a pull-up node and a first control voltage input end, and configured to control the pull-up node to be electrically connected to, or electrically disconnected from, the first control voltage input end in accordance with a potential at the pull-up node and an input potential at the first control voltage input end.