Gate Driver Loop Circuit Suppresses Noise During Touch Scanning
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Solution Overview
Problem
In touch display apparatuses, noise from voltage changes at transistor end points and pixel voltage changes on gate and source lines interferes with the operation of touch pens, requiring a solution to minimize this noise without affecting the display panel's functionality.
Innovation Solution
A gate driver with shift registers and loop circuits is used, where the loop circuits suspend gate signal output during touch scanning, and the source driver provides pixel voltages corresponding to black or low gray-scale values, reducing noise and allowing touch operations without disrupting the display panel's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display panel operates normally with continuous gate signal output, then the display function is maintained, but noise is generated that interferes with touch pen operation
Solution Approach 1:
The gate driver circuit alternates between display driving mode and touch scanning mode in periodic cycles. During touch scanning periods, the loop circuit suspends gate signal output to eliminate noise, while during display periods, normal gate signal output is restored. This periodic switching resolves the contradiction by making the harmful factor (noise) absent during critical touch operations.
Solution Approach 2:
The loop circuit is configured to suspend gate signal output in advance before touch scanning begins. The control circuit receives touch scanning start signals and proactively stops gate signal generation, preventing noise from being generated in the first place during touch operations, rather than attempting to filter or reduce it afterward.
2Object-generated harmful factors
If the loop circuit suspends gate signal output during touch scanning, then noise is reduced for touch operations, but display output may be affected
Solution Approach 1:
The system alternates between display driving mode and touch scanning mode in well-defined periodic cycles. During display periods, the loop circuit operates normally to maintain display output. During touch scanning periods, it suspends output to reduce noise. This periodic operation ensures both display functionality and touch accuracy are maintained at appropriate times.
Solution Approach 2:
The loop circuit automatically switches between display driving and touch scanning modes based on control signals from the control circuit, without requiring external intervention. The circuit self-regulates its operation to serve both display and touch functions appropriately, maintaining display output when needed and reducing noise when touch scanning occurs.
3Reliability
If the source driver provides pixel voltages continuously, then the display panel maintains normal operation, but noise is generated that affects touch sensitivity
Solution Approach 1:
The source driver circuit operates in periodic cycles, providing continuous pixel voltages during display periods and suspending or reducing output during touch scanning periods. This periodic operation maintains display functionality while eliminating noise interference during sensitive touch measurements, resolving the contradiction between continuous operation and noise reduction.
Data Source
AI summary
A gate driver and a touch display apparatus thereof are provided. The gate driver includes a plurality of shift registers and at least one loop circuit. The shift registers provide multiple gate signals to a touch display module. The loop circuit is coupled in series with the shift registers and receives at least one touch switching signal to set a loop time of the loop circuit. The touch display module performs at least one touch scan during the loop time.