Capacitive Touch Circuit Scanning for Wet-Surface Accuracy
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Solution Overview
Problem
Capacitive touch technology is adversely affected by water droplets, making it difficult to distinguish between finger touches and water-induced changes in coupling capacitance, leading to reduced accuracy and functionality in wet or water-exposed environments.
Innovation Solution
A touch control method that uses multi-frequency scanning signals or single-frequency non-sine wave signals to differentiate between touch data caused by fingers and water droplets by calculating the difference in capacitance changes, allowing for accurate determination of touch positions and enhancing waterproof properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive touch technology is used, then touch functionality is achieved, but water droplets cause false touch signals reducing accuracy
Solution Approach 1:
The patent applies dynamics by using multiple scanning frequencies (first frequency and second frequency) to dynamically probe the touch sensor. By varying the frequency of the scanning signal, the system can distinguish between finger touches and water droplets based on their different dielectric properties at different frequencies, thereby maintaining touch functionality while improving measurement precision in wet environments.
Solution Approach 2:
The patent changes the parameter of scanning signal frequency to differentiate between touch objects. By comparing touch signals obtained at different frequencies, the system can identify whether a touch is caused by a finger or water droplets, thus resolving the contradiction between maintaining touch functionality and ensuring accurate touch position detection in wet conditions.
2Adaptability or versatility
If water droplets are present on the touch screen, then capacitance coupling changes occur, but it becomes impossible to distinguish between finger and water-induced changes
Solution Approach 1:
The patent uses feedback by comparing touch signals obtained at different frequencies. The system analyzes the difference between first touch data (at first frequency) and second touch data (at second frequency) to determine whether a touch signal is caused by a finger or water droplets. This feedback mechanism allows the system to maintain adaptability in various touch scenarios while preventing loss of accurate touch information by filtering out water-induced false signals.
3Reliability
If multi-frequency scanning is used to differentiate finger touch from water droplets, then waterproof capability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the touch detection process into multiple frequency stages. The touch sensor is scanned at a first frequency to obtain first touch data, then scanned at a second frequency to obtain second touch data. This segmented approach allows the system to differentiate between finger touches and water droplets while managing device complexity through a systematic multi-frequency scanning methodology.
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
The method effectively eliminates the impact of water droplets on touch functionality, enabling the touch device to operate normally even in wet conditions by accurately distinguishing between finger and water-induced capacitance changes, thus improving waterproof and moisture-proof capabilities.
Implementation Method 1
a coupling capacitance Cm is formed between adjacent touch driving electrode TX and touch sensing electrode RX... a coupling capacitance CFT is formed between the touch driving electrode TX and the finger, and a coupling capacitance CFR is formed between the touch sensing electrode RX and the finger
Implementation Method 2
an electrical coupling is formed between the touch sensing electrode RX, the touch driving electrode TX, and the finger
Implementation Method 3
the single-frequency non-sine wave scanning signal can be decomposed into a fundamental wave and one harmonic wave, separating the second original sensing data into first touch data corresponding to the fundamental wave and second touch data corresponding to the one harmonic wave
Data Source
AI summary
A touch control method, a touch control circuit system, and a touch device, the touch device includes a plurality of touch electrodes, the touch control method includes: step S1, sending a scanning signal to the plurality of touch electrodes; step S2, acquiring first touch data and second touch data according to the scanning signal; and step S3, the touch device defining a plurality of touch nodes, each of the plurality of touch nodes corresponding to the first touch data and the second touch data, defining at least one target touch node according to a difference between the first touch data and the second touch data, and calculating a current touch position according to the first touch data and the second touch data of the at least one target touch node.