Capacitive Touch Panel Water Detection via Inverted Capacitance Logic
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Solution Overview
Problem
Capacitive touch panels struggle to detect touch operations in water environments due to uniform capacitance increases across the panel, making it difficult to differentiate between contact and non-contact regions.
Innovation Solution
The electronic device employs a capacitive touch panel with a controller that detects a region with lower capacitance than the rest of the panel as the contact region, utilizing a material with relative permittivity lower than water to minimize capacitive coupling with water, allowing touch operations in wet conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive touch panel is used to detect touch operations, then touch detection is enabled through capacitance changes, but the panel cannot differentiate contact regions from non-contact regions when exposed to water due to uniform capacitance increases
Solution Approach 1:
The patent applies local quality by creating a contact object with non-uniform capacitance distribution, where the contact region has different capacitance characteristics than the surrounding non-contact regions. This allows the touch panel to distinguish between contact and non-contact areas even when the entire panel is exposed to water, as the contact region maintains a distinct capacitance signature.
Solution Approach 2:
The patent inverts the traditional touch detection approach by detecting regions with smaller capacitance values rather than larger ones. When water causes uniform capacitance increases across the panel, the contact region appears as a local minimum (smaller capacitance) rather than a maximum, enabling touch detection to work in reverse logic when exposed to water.
2Adaptability or versatility
If the touch panel is exposed to water environment, then waterproof usage is enabled, but capacitance uniformity increases making contact region identification difficult
Solution Approach 1:
The contact object is designed with localized capacitance characteristics that differ from the surrounding area. This local quality ensures that even when water causes uniform capacitance changes across the entire panel, the contact region maintains a distinct capacitance profile that can be identified by the controller.
Solution Approach 2:
The detection method is inverted to search for local minimum capacitance regions instead of local maximums. This inversion allows the system to identify contact regions as areas with smaller capacitance values relative to their surroundings, enabling accurate touch detection in water environments where traditional maximum-detection methods fail.
3Measurement precision
If conventional capacitive detection methods are used, then touch detection works in air, but the method fails to detect touches in water due to capacitive coupling with water
Solution Approach 1:
The patent inverts the detection logic from seeking maximum capacitance regions to seeking minimum capacitance regions. This inversion allows the same capacitive touch panel to function in both air and water environments by adapting the detection criterion: in air, contact regions show increased capacitance, while in water, contact regions show decreased capacitance relative to surroundings.
Solution Approach 2:
The patent changes the detection parameter from looking for capacitance increases to looking for capacitance decreases. By changing the detection threshold and direction, the system can distinguish contact regions from non-contact regions regardless of whether the panel is in air or water, making the touch detection adaptable to different environmental conditions.
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
Enables reliable touch detection and operation in water by identifying regions with reduced capacitance, effectively distinguishing contact points amidst uniform capacitance changes caused by water exposure.
Implementation Method 1
the controller, based on a detection value of the touch panel, detects capacitance generated between the touch panel and a contact object
Implementation Method 2
When the touch panel of the capacitive type is touched, capacitance at a touched position changes due to static electricity
Implementation Method 3
utilizing a material with relative permittivity lower than water to minimize capacitive coupling with water
Data Source
AI summary
An electronic device is provided with a touch panel of a capacitive type and a controller. The controller, based on a detection value of the touch panel, detects capacitance generated between the touch panel and a contact object and detects, as a contact region, a first region having the capacitance smaller than a capacitance of the other region of the touch panel.