Touch Sensor Mutual Self-Capacitance Alternating Detection
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Solution Overview
Problem
Mutual capacitance detection in touch sensors experiences a 'floating effect' when using larger fingers or objects, leading to incorrect multi-touch judgments and difficulty in distinguishing single versus multi-touch inputs, especially with the thumb, due to signal cancellation and increased peripheral capacitance.
Innovation Solution
Alternating between mutual capacitance and self-capacitance modes for touch detection, implementing envelopment analysis in the self-capacitance mode to accurately determine single or multi-touch states and adjust reference values, thereby improving touch detection accuracy and reducing the floating effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mutual capacitance detection is used, then multi-touch capability is achieved, but floating effect occurs causing incorrect touch judgment
Solution Approach 1:
The patent combines mutual capacitance detection and self capacitance detection into a unified touch detection system. The controller alternates between the two detection modes, using mutual capacitance for multi-touch capability and self capacitance for accurate single-touch detection, thereby resolving the floating effect problem while maintaining multi-touch functionality.
Solution Approach 2:
The patent implements dynamic switching between mutual capacitance detection mode and self capacitance detection mode based on touch detection needs. The controller dynamically selects the appropriate detection mode for each scanning cycle, allowing the system to adapt to different touch scenarios and eliminate floating effect artifacts.
2Reliability
If self capacitance mode is used, then floating effect is reduced, but multi-touch detection capability is lost
Solution Approach 1:
The patent merges the advantages of both mutual capacitance detection (multi-touch capability) and self capacitance detection (floating effect resistance) into a single hybrid detection system. By alternating between the two modes, the system achieves both accurate single-touch detection and multi-touch capability.
Solution Approach 2:
The controller performs periodic switching between mutual capacitance detection and self capacitance detection in alternating scanning cycles. This periodic action allows the system to leverage the strengths of both detection modes at different times, achieving accurate touch judgment while maintaining multi-touch functionality.
3Reliability
If metal housing is used to solve floating effect, then ground area increases, but device complexity and manufacturing limitations arise
Solution Approach 1:
The patent replaces the mechanical solution (metal housing with increased ground area) with an electronic/software solution (alternating mutual and self capacitance detection modes). This substitution eliminates the need for complex metal housing structures while effectively solving the floating effect problem through intelligent detection mode switching.
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
Enhances the accuracy of touch detection, particularly in distinguishing single and multi-touch inputs during large area touches, effectively addressing the floating effect and improving user experience by reducing signal noise and incorrect judgments.
Implementation Method 1
the mutual capacitance detection has the feature of multi-touch... The floating effect means the touch terminal is on the surface of a high insulation object... Ch is respectively the impedance and capacitive reactance between the body and ground
Data Source
AI summary
The present disclosure relates to a touch technology field, provides a touch detecting method for a touch sensor, the method comprises the following steps: putting the touch sensor into a mutual capacitance mode and a self capacitance mode alternatively, and scanning and detecting the rows and columns of a capacitance array of the touch sensor; when a touch state is preliminarily judged as no touch according to a scanning and detecting result in the mutual capacitance mode, implementing envelopment analysis for data obtained by sampling in the self capacitance mode and determining whether the touch exists in the mutual capacitance mode, updating no reference in the mutual capacitance mode if the touch exists, and updating the reference in the mutual capacitance mode if no touch exists.