Touch Detection Circuit Water Contact Differentiation
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Solution Overview
Problem
Conventional smart watch touch panels experience touch detection errors when the metal frame comes into contact with water, as water acts as a perfect conductor, generating false touch data similar to finger touches.
Innovation Solution
A touch detection circuit with first and second detection circuits that select and transmit specific signals to boundary and central areas of the touch panel, respectively, to detect capacitance variations and differentiate between water and finger contacts, thereby improving detection reliability without affecting normal touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water touches the metal frame of the smart watch, then the metal frame conducts electricity perfectly, but this causes grounding and generates false touch data similar to finger touch
Solution Approach 1:
The touch panel is divided into multiple independent detection areas (first touch area, second touch area, third touch area, fourth touch area) with distinct detection circuits. Each area can be independently detected, allowing the system to identify which specific area is affected by water contact and differentiate it from genuine finger touches through localized capacitance analysis.
Solution Approach 2:
Different detection strategies are applied to different areas of the touch panel. Boundary areas (first and fourth touch areas) use one detection method while central areas (second and third touch areas) use another. This local differentiation allows the system to adapt to varying capacitance characteristics in different regions and improve water detection accuracy.
2Device complexity
If the touch panel is divided into multiple areas and detected sequentially in time division manner, then the detection process is simplified, but this reduces the ability to detect simultaneous water contact across multiple areas
Solution Approach 1:
The detection system performs periodic sequential scanning of different touch areas in a time-division manner. Each area is detected at specific time intervals (first detection time, second detection time, third detection time, fourth detection time), allowing the system to monitor capacitance changes across all areas over time and identify water contact patterns that may affect multiple areas.
3Ease of operation
If conventional touch detection is used without differentiation between water and finger contact, then the detection method is simple, but this results in touch detection errors when water contacts the metal frame
Solution Approach 1:
The system monitors changes in capacitance parameters across different touch areas and over time to differentiate between water contact and finger touch. By analyzing capacitance variations in boundary areas versus central areas, and comparing detection results across multiple time points, the system can distinguish water-induced capacitance changes from genuine touch events.
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 solution effectively differentiates between water and finger contacts, enhancing the reliability of touch detection on smart watches by utilizing capacitance variations between boundary and central areas, thus reducing false positives caused by water contact with the metal frame.
Implementation Method 1
detect capacitance variations and differentiate between water and finger contacts
Data Source
AI summary
A touch detection circuit and a touch detection method are provided. The touch circuit coupled to touch areas of touch panel includes a touch controller and a detection circuit. The touch controller performs a touch detection on the touch areas sequentially. The detection circuit transmits a first detection signal to a boundary area of the touch areas which are not touch detected to receive a first feedback signal. The detection circuit transmits a second detection signal to a corresponding central area of the touch areas which are not touch detected to receive a second feedback signal. The touch controller compares the first feedback signal and the second feedback signal to generate a capacitance variation between the boundary area and the corresponding central area.