Capacitive Touch Sensor Layout for Finger-Water Discrimination
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Solution Overview
Problem
Conventional capacitive touch sensors often trigger false touch events due to the presence of water, which is undesirable and can lead to incorrect interpretations of touch stimuli.
Innovation Solution
A capacitive touch sensor design featuring a plurality of drive electrodes and a reception electrode, forming two capacitors, which distinguishes between touch events caused by a human finger and non-touch events caused by water by selectively connecting electrodes to supply and ground voltages, thereby generating distinct output voltages based on capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional capacitive touch sensor detects capacitance changes, then it can detect touch events, but it also triggers false touch events when water is present
Solution Approach 1:
The sensor is divided into multiple drive electrodes (first drive electrode, second drive electrode) and a reception electrode, forming multiple capacitors (first capacitor, second capacitor). This segmentation allows the system to analyze capacitance changes from different electrodes and distinguish between water presence and actual touch events through comparative analysis of the capacitance patterns.
2Measurement precision
If the sensor uses multiple capacitors formed by drive electrodes and reception electrode, then it can distinguish between finger touch and water presence, but the device complexity increases
Solution Approach 1:
The multiple drive electrodes and reception electrode serve multiple functions: they form multiple capacitors for differential measurement, enable both water detection and touch detection modes, and provide redundant sensing capability. This multi-functionality allows the same electrode structure to address both false touch prevention and accurate touch detection without requiring separate dedicated components.
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 differentiates between human touch and water presence, ensuring accurate detection of touch events and preventing false triggers, allowing for reliable operation in various applications such as automotive and security systems.
Implementation Method 1
Mutual capacitive touch sensors operate by detecting and/or measuring the capacitance of a capacitive sense element, and detecting and/or measuring a change in capacitance indicating a touch or presence of a conductive object
Data Source
AI summary
Various embodiments of the present technology may comprise methods and apparatus for a touch sensor. The capacitive touch sensor may comprise a plurality of drive electrodes and a reception electrode, wherein two capacitors are formed. Under various conditions, the capacitive touch sensor may be configured to trigger a touch event in the presence of a human finger and trigger a non-touch event in the presence of water.