Capacitive Input Sensing for Moisture and Touch Discrimination
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Solution Overview
Problem
Capacitive sensor devices face difficulties in accurately detecting user input in humid environments due to moisture interference, which affects their functionality.
Innovation Solution
The method involves using a combination of parallel transcapacitance sensing (PTS) and absolute capacitance sensing (ABS) schemes to determine the presence of moisture on the sensing region by analyzing grounding conditions and comparing resulting signals from electrodes oriented on the same axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitive sensing is used, then the device can detect user input, but moisture on the surface interferes with the detection accuracy
Solution Approach 1:
The electrode array is segmented into multiple groups that can be independently driven and sensed. By dividing the sensing region into discrete electrode segments, the system can selectively activate specific areas and compare their responses to distinguish between moisture and user input patterns.
Solution Approach 2:
The system changes the driving parameters by applying different drive signals to different electrode groups and using multiple sensing schemes (PTS and ABS). By varying the electrical parameters and sensing methods, the system creates distinct signal patterns that allow differentiation between moisture presence and actual user input.
2Measurement precision
If multiple sensing schemes are implemented to distinguish moisture from user input, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The same electrode array serves multiple functions by supporting both parallel transcapacitance sensing (PTS) and absolute capacitance sensing (ABS) schemes. The electrodes are configured to perform both moisture detection and user input detection, eliminating the need for separate sensor arrays and reducing overall system complexity.
Solution Approach 2:
The system creates multiple signal representations by driving electrodes in different configurations and sensing modes. By generating parallel sets of signals through different sensing schemes, the system can compare and cross-validate results to improve detection accuracy without adding physical hardware complexity.
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 performance by accurately distinguishing between moisture and user input, improving the device's functionality in humid conditions.
Implementation Method 1
A capacitive sensor device may include a sensing region, often demarked by a surface (e.g., display screen), in which the capacitive sensor device determines the presence, location and/or motion of one or more input objects
Implementation Method 2
the capacitive sensor device determines the presence, location and/or motion of one or more input objects
Data Source
AI summary
A method for capacitive sensing is provided. The method comprises: obtaining, by a processing system and using a first set of electrodes from a plurality of electrodes of an input device, first resulting signals based on driving a second set of electrodes from the plurality of electrodes, wherein the first set of electrodes and the second set of electrodes are oriented on a same axis of orientation; obtaining, by the processing system, second resulting signals based on operating a third set of electrodes from the plurality of electrodes in an absolute capacitance sensing (ABS) scheme; and determining, by the processing system, a presence of moisture on a sensing region of the input device based on the first resulting signals and the second resulting signals.