Capacitive Touch Coordinate Extraction via Dual-Phase Scanning
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Solution Overview
Problem
Capacitive touch systems face challenges in achieving high coordinate precision due to noise deviations between adjacent sensors, which affects the performance and accuracy of touch detection in mobile devices.
Innovation Solution
A method for extracting touch coordinates in a capacitive touch system involves applying drive signals in alternating directions during different phases, using a weighted mean extraction algorithm to select coordinates with high precision, and employing a partial-scan method to reduce noise and improve touch precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single-direction scanning method is used, then the system operation is simple, but the coordinate precision is low due to noise deviations between adjacent sensors
Solution Approach 1:
The patent divides the touch sensing process into multiple phases (first phase and second phase), where each phase scans in a different direction. By segmenting the scanning process into directional components, the system can average out noise deviations that occur in specific directions, thereby improving coordinate precision without requiring fundamentally complex hardware changes
Solution Approach 2:
The patent implements periodic alternation between first-direction scanning and second-direction scanning across different frames. This periodic switching allows the system to collect data from multiple directional perspectives and combine them through weighted mean extraction, reducing the impact of directional noise patterns and improving overall measurement precision
2Measurement precision
If full-scan method is used in both phases, then the coordinate precision is improved, but the processing time increases
Solution Approach 1:
The patent applies partial scanning in the second phase by focusing only on nearby pattern areas surrounding the touch location identified in the first phase, rather than performing a complete full-scan. This partial action approach maintains coordinate precision by concentrating computational resources on the relevant touch region while significantly reducing the time required for processing
Solution Approach 2:
The first phase performs a full-scan to preliminarily identify the touch location, which then serves as the basis for optimizing the second phase scanning. By using the preliminary results to guide the subsequent partial-scan, the system avoids redundant scanning of areas far from the touch point, thereby reducing processing time while maintaining precision
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 enhances touch coordinate precision by reducing noise deviations and improving touch detection accuracy, leading to better performance and faster reaction times in capacitive touch systems.
Implementation Method 1
Capacitive touch system sensing variations of mutual capacitance
Data Source
AI summary
The inventive concept discloses a capacitive touch system and a coordinate extraction method thereof. The coordinate extraction method has operations of phases 1 and 2.First and second axis coordinates of a first frame are obtained by providing driving signals in a first direction selected in the first phase and performing a sensing in a second direction different from the first direction. First and second axis coordinates of a second frame are obtained by providing driving signals in a second direction selected in the second phase and performing a sensing in the first direction. First and second axis coordinates having a relatively high coordinate precision among the first and second axis coordinates may be finally determined as a touch coordinate. According to the inventive concept, since a touch sensing precision is improved to be strong against a noise, a touch coordinate is more precisely obtained.