In-Cell Touch Screen Noise Cancellation via Signal Segmentation
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Solution Overview
Problem
In-cell touch screens face issues with low signal noise ratio (SNR) and false touches when display and touch drives are performed simultaneously, leading to inadequate time allocation for both display and touch drive durations, especially in large-size and high-resolution screens.
Innovation Solution
The method involves providing gate drive signals to gate lines and touch drive signals to drive lines concurrently, collecting original touch signals from sensing lines, defining interference signals caused by gate drive signals as noise, and removing these to obtain valid touch signals, thereby enhancing touch accuracy and user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If display drive and touch drive are performed simultaneously in one scanning period, then the charging and discharging of TFTs on the array substrate can be completed within the scanning period, but capacitive couplings generate noises that affect touch function and cause low signal noise ratio (SNR) and false touch
Solution Approach 1:
The patent segments the scanning period into multiple sub-periods, dividing the simultaneous display and touch drive operations into distinct time segments. This allows the system to maintain high productivity by utilizing the full scanning period while reducing noise interference through temporal separation of critical operations.
Solution Approach 2:
The patent implements periodic action by alternating between display drive periods and touch drive periods within the scanning cycle. This periodic segmentation enables both functions to be performed systematically, with noise reduction achieved during specific phases while maintaining overall operational efficiency.
2Reliability
If display drive time duration T1 and touch drive time duration T2 are extended to ensure both display effect and touch detection effect, then better display and touch performance are achieved, but there may not be enough time allocated in one scanning period
Solution Approach 1:
The patent applies dynamics by making the scanning period structure flexible and adaptive. The system dynamically adjusts the allocation of time between display and touch operations based on current requirements, allowing extended drive durations when needed while maintaining scanning period constraints through optimized timing sequences.
Solution Approach 2:
The patent ensures continuity of useful action by overlapping certain operations and eliminating idle time between display and touch drive sequences. This allows both functions to proceed with extended effective durations without creating gaps in the scanning period, maximizing time utilization while maintaining reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively removes interference signals from TFT charging, reduces severe touch noise, and enhances the signal noise ratio (SNR) of touch signals, improving touch accuracy and user experience by extending the scanning periods for both display and touch drives.
Implementation Method 1
capacitive couplings may be generated from the charging and discharging of the TFTs and turn into noises
Data Source
AI summary
An In-cell touch screen and a method for driving the same includes: concurrently providing a plurality of gate drive signals to the plurality of gate lines line by line and a plurality of touch drive signals to the plurality of drive lines line by line, collecting original touch signals from the plurality of sensing lines line by line; when collecting is performed on a sensing line and any gate line covered by the sensing line is supplied with a gate drive signal, defining the original touch signals collected from a sensing line as interference signals; and removing the interference signals from the original touch signals to obtain a valid touch signal.