Capacitive Sensing Device for Irregular Conductive Matter Detection
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Solution Overview
Problem
Capacitive sensing devices face issues with false determinations and incorrect touch location identification due to irregular conductive matter, such as water, which alters the equivalent circuit and parasitic capacitance, leading to false motion and incorrect reporting.
Innovation Solution
A capacitive sensing device and method that involves scanning detection points to obtain sensing signals, computing signal summations, and setting a flag based on changes in these signals to disable reporting of touch points when irregular conductive matter is detected, thereby distinguishing between true touch events and false motions caused by irregular conductive matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensing device uses conventional touch detection method, then touch sensitivity is maintained, but false determination occurs due to irregular conductive matter
Solution Approach 1:
The patent segments the touch detection process into multiple independent analysis dimensions: (1) scanning multiple detection points to obtain sensing signals, (2) computing signal summation of positive and negative signals separately, (3) comparing current signal summation with previous signal summation to detect changes, and (4) using flag variables to mark irregular conductive matter regions. This segmentation allows the system to distinguish between genuine touch events and false motions caused by irregular conductive matter like water droplets.
Solution Approach 2:
The patent performs preliminary scanning of multiple detection points before making a touch determination. By pre-computing the signal summation and comparing it with previous signal summation, the system identifies irregular conductive matter regions in advance. The flag variable is set based on this preliminary analysis, preventing false touch reports before they occur.
2Measurement precision
If capacitive sensing device detects touch in irregular conductive matter region, then touch location is identified, but incorrect reporting occurs
Solution Approach 1:
The patent implements a feedback mechanism where the sensing controller continuously monitors sensing signals from multiple detection points, computes signal summation, and compares current signal summation with previous signal summation. Based on this feedback loop, the controller sets or clears flag variables to accurately identify irregular conductive matter regions and prevent incorrect touch location reporting.
Solution Approach 2:
The patent adds an additional dimension of analysis by introducing flag variables that operate independently from the standard touch detection flow. This dimensional separation allows the system to overlay irregular conductive matter detection information onto the touch detection process, enabling accurate differentiation between genuine touches and false motions.
3Object-affected harmful factors
If capacitive sensing device uses signal summation method, then false motion is detected, but additional processing complexity is introduced
Solution Approach 1:
The patent changes the parameter representation by computing signal summation of positive and negative sensing signals separately, rather than processing individual sensing signals. This parameter transformation simplifies the detection logic by converting multiple individual signal comparisons into a single summation comparison, reducing processing complexity while maintaining false motion detection capability.
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
Effectively prevents false motion and incorrect touch location reporting by accurately identifying touch events on capacitive sensing devices, even in the presence of irregular conductive matter, enhancing the reliability of touch screen operations.
Implementation Method 1
capacitive sensing device... the equivalent circuit and equivalent parasitic capacitance between the axial conductive lines in the region change accordingly... the control sensing circuit picks up a change in the electrical current or charge transferred on the axial conductive lines
Implementation Method 2
the equivalent circuit and equivalent parasitic capacitance between the axial conductive lines in the region change accordingly
Data Source
AI summary
A detection method for an irregular conductive matter in a touch event includes scanning a plurality of detection points to obtain a plurality of sensing signals of the detection points; computing a first signal summation of all positive signals among the sensing signals; obtaining a first change between the first signal summation and a previous first signal summation; computing a second signal summation of all negative signals among the sensing signals; obtaining a second change between the second signal summation and a previous second signal summation; setting a flag according to the first change and the second change when the first change and the second change are positive; clearing the flag according to the first change and the second change when the first change and the second change are negative; and disabling a reporting of at least one touch point when the flag exists.