Self-Capacitance Touch Screen Signal Detection with Equipotential Driving
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Solution Overview
Problem
Current self-capacitance touch screens face issues with low signal-to-noise ratio (SNR) during touch signal detection, leading to inaccurate signal detection and potential functional failures or mistouches due to charge transfer and weakened electrical signals.
Innovation Solution
The method involves simultaneously inputting driving signals to a to-be-scanned sensor pad group and an adjacent sensor pad group, while grounding all other sensor pad groups, to eliminate potential differences and reduce power consumption, thereby improving the SNR and precision of touchpoint coordinates detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If driving signals are inputted into sensor pad groups group by group sequentially, then the detection process can be completed, but potential differences are generated between sensor pad groups causing charge transfer and weakened electrical signals
Solution Approach 1:
The patent applies equipotentiality by inputting the same driving signals to both the to-be-scanned sensor pad group and the adjacent sensor pad group simultaneously. This keeps both groups at the same potential level, eliminating potential differences and preventing charge transfer between groups, thereby maintaining signal accuracy while enabling sequential detection
2Reliability
If driving signals are inputted to multiple sensor pad groups simultaneously, then charge transfer is prevented, but power consumption increases
Solution Approach 1:
The patent segments the sensor pad groups into two categories: the to-be-scanned group and the adjacent group. Only these two groups receive driving signals simultaneously, while other groups are grounded. This segmented approach limits the number of active groups, reducing overall power consumption while still preventing charge transfer for the detected group
Solution Approach 2:
The patent applies partial action by activating only the necessary sensor pad groups (to-be-scanned and adjacent groups) rather than all groups simultaneously. This partial activation is sufficient to prevent charge transfer for the current detection while minimizing power consumption across the entire touch screen
3Reliability
If all sensor pad groups are kept active during detection, then charge transfer is minimized, but the signal-to-noise ratio decreases due to accumulated noise
Solution Approach 1:
The patent extracts and grounds all sensor pad groups except for the to-be-scanned group and the adjacent group. By removing (grounding) the unnecessary active groups, the patent eliminates noise sources from inactive groups while maintaining charge transfer prevention for the active groups, thereby improving the signal-to-noise ratio
Data Source
AI summary
A self-capacitance touch screen, a method of detecting thereof, and a device for detecting thereof are provided. The method of detecting the self-capacitance touch screen includes following steps: outputting same driving signals to a to-be-scanned sensor pad group and an adjacent sensor pad group and correspondingly recognizing coordinates of touch points according to changes in received driving signals.