Touch Screen Scanning Method Resolving Signal Interference
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Solution Overview
Problem
Current touch screens, especially those using in-cell technology, face interference between display signals and touch signals due to simultaneous scanning methods, leading to inaccurate sampling and unstable display performance.
Innovation Solution
Implementing a touch screen scanning method where display scans and touch scans, such as capacitive and electromagnetic scans, are performed in a time-sharing manner within each frame scanning cycle, ensuring only one type of scan is conducted in each period to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If display scan, capacitive touch scan, and electromagnetic touch scan are performed in the same period to increase scanning frequency, then scanning frequency is improved, but signal interference occurs between the scans
Solution Approach 1:
The patent implements periodic scanning by dividing the frame scanning cycle into multiple periods, where each period is dedicated to a specific scanning function (display scan in odd periods, capacitive touch scan in even periods, electromagnetic touch scan in alternating even periods). This periodic allocation eliminates signal interference while maintaining continuous scanning operations across all functions.
2Length of stationary object
If capacitive screen and electromagnetic screen are integrated inside the display panel using in-cell technology to reduce thickness, then device thickness is reduced, but signal interference between display, capacitive touch, and electromagnetic touch signals increases
Solution Approach 1:
The patent applies periodic scanning by allocating different scanning functions to different time periods within each frame cycle. Display scans occur in odd periods while capacitive and electromagnetic touch scans occur in even periods, with electromagnetic scans alternating between different even periods. This temporal separation prevents signal interference despite the physical integration of all layers in the in-cell structure.
3Adaptability or versatility
If electromagnetic wave band of electromagnetic pen overlaps with display signal frequency band to enable simultaneous operation, then device functionality is maintained, but sampling accuracy of electromagnetic touch signal deteriorates
Solution Approach 1:
The patent resolves the frequency band conflict by implementing periodic scanning where electromagnetic touch scans are performed in alternating even periods while display scans occur in odd periods. This temporal separation allows the electromagnetic pen's frequency band to be used exclusively for touch scanning during its designated periods, eliminating interference with display signals and ensuring accurate sampling without sacrificing functional compatibility.
Data Source
AI summary
A touch screen scanning method, a device, and a system are provided. Only a display scan or one touch scan is performed in each period of each frame scanning cycle, and then the display scan and/or at least one touch scan is completed in each frame scanning cycle. The display scan and the at least one touch scan do not interfere with each other during each process, thereby ensuring accuracy of a scan result and display performance of a touch screen.