Underwater Touch Circuit Using Capacitance Decrease Detection
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Solution Overview
Problem
Existing underwater input devices face challenges with false touch detection due to water interference with electrostatic capacitance switches and require mechanical switches, which are difficult to operate with gloves and costly to seal.
Innovation Solution
A control circuit with a sensor electrode, capacitance sensor, and processing unit that detects a decrease in electrostatic capacitance to determine touch input, allowing for an electrostatic switch that functions underwater without false detection and reduces operational complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electrostatic capacitance switch is used underwater, then touch input detection is enabled, but false detection occurs due to water adhesion creating parallel capacitance
Solution Approach 1:
The patent inverts the conventional capacitance detection logic: instead of detecting capacitance increase on touch (standard electrostatic method), it detects capacitance decrease. Water adhesion increases capacitance, so the system identifies valid touch input when capacitance decreases below a threshold, effectively using the harmful water capacitance as a reference point for valid input detection.
Solution Approach 2:
The patent changes the detection parameter from capacitance increase (conventional method) to capacitance decrease. By setting a threshold value and detecting when measured capacitance falls below this threshold, the system distinguishes valid touch input from water adhesion effects, resolving the false detection problem while maintaining underwater adaptability.
2Reliability
If a mechanical switch is used underwater, then false detection is avoided, but operation becomes difficult with thick waterproof gloves and sealing costs increase
Solution Approach 1:
The patent replaces the mechanical switch system with an electrostatic capacitance-based detection system. This substitution eliminates the need for mechanical moving parts that require sealing and are difficult to operate with gloves, while achieving reliable detection underwater through the inverted capacitance detection method that accounts for water adhesion effects.
3Measurement precision
If continuous capacitance sensing is performed, then touch input detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic capacitance sensing instead of continuous monitoring. The control circuit performs capacitance measurement at predetermined intervals, which maintains adequate touch input detection accuracy while significantly reducing power consumption compared to continuous sensing. This periodic action is sufficient for detecting user interactions that occur at discrete moments.
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 input detection underwater without the need for fine operations and reduces power consumption by adjusting sensing intervals, improving operability and reducing costs.
Implementation Method 1
a capacitance sensor coupled to the sense pin, and configured to detect the electrostatic capacitance formed by the sensor electrode
Data Source
AI summary
A control circuit controls an input apparatus to be used underwater. A sense pin is coupled to a sensor electrode arranged so as to allow the user wearing equipment to touch the sensor electrode. A capacitance sensor is coupled to the sense pin, and detects the electrostatic capacitance formed by the sensor electrode. When the electrostatic capacitance Cs detected by the capacitance sensor becomes lower than a predetermined threshold value, the processing unit judges that a touch input by the user has occurred.