Sealed User Interface Combining Inductive and Capacitive Sensing
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Solution Overview
Problem
Existing user interfaces for portable electronic devices, particularly wearable devices, are prone to erroneous activation due to environmental factors such as water or metal proximity, lacking robustness and simplicity in function activation.
Innovation Solution
A switch interface utilizing a flexible conductive element that deforms above a current-carrying coil, changing mutual inductance, which is electrically isolated from the sensing electronics, allowing operation in various environments, including underwater, and incorporating both inductive and capacitive sensing for robust detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive sensing is used for user interface, then it can detect dielectric materials like water, but it causes erroneous activation in environmental conditions
Solution Approach 1:
The patent divides the sensing function into two separate sensing mechanisms: capacitive sensing for proximity detection and inductive sensing for activation detection. This segmentation allows each sensing type to perform its optimal function without interference, resolving the contradiction between versatility and reliability.
Solution Approach 2:
The patent introduces an intermediary conductive element that couples the user interface to the sensing coil. This intermediary enables inductive sensing to detect user interaction while being isolated from direct environmental factors that cause erroneous capacitive activation, thus improving reliability while maintaining detection capability.
2Reliability
If inductive sensing is used for user interface, then it is limited to conductive materials and ferrites, but it provides reliable detection
Solution Approach 1:
The patent merges capacitive sensing and inductive sensing into a unified user interface system. The capacitive sensor detects proximity of any dielectric material (providing versatility), while the inductive sensor confirms actual user activation (providing reliability). This combination resolves the contradiction between material compatibility and detection accuracy.
3Reliability
If the switch mechanism is electrically isolated from user interface, then it protects electrical components, but it complicates the sensing mechanism
Solution Approach 1:
The patent replaces direct mechanical contact between the user interface and electrical components with a magnetic field-based inductive sensing system. The conductive element moves in response to user input and couples magnetically with the sensing coil, eliminating the need for direct electrical connections while simplifying the overall system architecture despite the advanced sensing mechanism.
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
Provides a user interface that is resistant to environmental interference, ensuring accurate and intuitive operation without increased complexity or cost, with the ability to detect user interactions reliably.
Implementation Method 1
A switch interface utilizing a flexible conductive element that deforms above a current-carrying coil, changing mutual inductance
Data Source
AI summary
The invention concerns a robust user interface for electronic devices where a single measurement circuit is used to measured inductance values due to user press events through sealable surface, as well as capacitance values due to user proximity and/or touch events, and with both the measured inductance and capacitance values used to determine user input commands.