Resonant Touch Sensor Layout for Sealed Wearable Switching
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Solution Overview
Problem
Conventional mechanical switches occupy significant space, are not aesthetically pleasing, and pose risks due to direct user contact and challenges in achieving dustproof and waterproof designs, limiting their integration in wearable devices.
Innovation Solution
A touch sensing device with a deformable bracket, a capacitance pad, and a sensing coil forming resonant circuits that generate signals based on touch location and pressure, allowing for contact and force touch detection without the need for a mechanical switch, thus enabling a compact and safe design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional mechanical switch is used, then switching function is achieved, but device space is occupied and design neatness is compromised
Solution Approach 1:
The patent replaces the mechanical switch structure with a capacitive sensing system consisting of a sensing electrode, reference electrode, and detection circuit. The switching function is achieved through detecting changes in capacitance caused by finger proximity or contact, eliminating the need for mechanical moving parts and reducing device space occupation.
Solution Approach 2:
The patent introduces an intermediary detection mechanism where the sensing electrode detects electrical field changes caused by the human body's proximity or contact. This intermediary approach allows the system to detect touch input without direct mechanical contact between the user and the switch mechanism.
2Reliability
If a conventional mechanical switch is used, then switching function is achieved, but dustproof and waterproof capabilities are compromised
Solution Approach 1:
By replacing the mechanical switch with a capacitive sensing system, the patent eliminates physical openings, gaps, and moving parts that would allow dust and water penetration. The sensing electrodes and protective coating create a sealed structure that maintains dustproof and waterproof capabilities while achieving switching functionality.
3Reliability
If a conventional mechanical switch is used, then switching function is achieved, but user safety is compromised due to direct contact
Solution Approach 1:
The patent uses the human body's natural capacitance as an intermediary between the user and the switching function. The sensing electrode detects changes in the electrical field caused by the user's proximity or contact, allowing the system to respond to touch without requiring direct electrical contact between the user and the device's internal circuitry.
4Measurement precision
If a touch sensing device with resonant circuit is used, then touch detection precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a resonant circuit that serves multiple functions: it generates the sensing signal, amplifies the touch-induced capacitance changes, and provides frequency-based filtering. The resonant circuit operates at a specific frequency to enhance sensitivity to touch inputs while rejecting noise at other frequencies, achieving high detection precision without requiring separate signal generation and filtering circuits.
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 allows for efficient detection of touch inputs in a compact form factor, enhancing user safety and design aesthetics while maintaining dustproof and waterproof capabilities.
Implementation Method 1
The sensing coil may have an inductance that varies while the sensing coil moves in a touch application direction of the applied touch
Implementation Method 2
The sensing coil and the pad may be electrically connected to each other to form a resonant circuit, and the resonant circuit may generate a resonance signal having a resonant frequency that varies as the touch is applied
Implementation Method 3
the pad having a capacitance that varies as a touch is applied proximate to the device
Data Source
AI summary
A device with touch sensing includes a bracket, a pad disposed above one side of the bracket, the pad having a capacitance that varies as a touch is applied proximate to the device, and a sensing coil disposed below another side of the bracket that opposes the one side, with at least a portion of the sensing coil overlapping the pad.