Inductive Touch Screen Force Sensing for Wet, Glove-Wearing Operation
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Solution Overview
Problem
Capacitive touch screens are expensive, susceptible to water and liquids, and can be affected by user gloves, leading to degraded functionality and increased wear.
Innovation Solution
A touch screen using inductive force sensing technology measures user pressure on the screen surface to determine selection points without capacitive or resistive sensing, utilizing sensors in the corners for triangulation and providing haptic, light, or sound feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensing is used for touch screen, then resolution and ease of use are improved, but cost and susceptibility to water/liquids increase
Solution Approach 1:
The patent replaces capacitive sensing (electrical field-based) with inductive force sensing (magnetic field-based). The inductive sensors detect changes in inductance caused by mechanical pressure on the screen, substituting the capacitive measurement mechanism with an inductive one that is inherently immune to water and liquid interference.
Solution Approach 2:
The patent changes the measurement parameter from capacitance (voltage-based) to inductance (current-based). By measuring changes in inductance rather than capacitance, the system achieves immunity to water and liquids while maintaining touch detection capability through force-based measurement.
2Ease of operation
If capacitive sensing is used for touch screen, then ease of operation is improved, but cost increases due to transparent connections and wiring
Solution Approach 1:
The patent replaces the complex capacitive sensing infrastructure (transparent ITO connections, wiring, and connectors) with simpler inductive force sensors. The inductive sensing mechanism eliminates the need for extensive conductive pathways across the screen surface, reducing wiring complexity and associated costs.
3Reliability
If inductive force sensing is used, then resistance to water and liquids is improved, but measurement precision compared to capacitive touch decreases
Solution Approach 1:
The patent divides the touch screen into discrete segments or zones, each monitored by inductive force sensors. By segmenting the detection area and using triangulation methods with multiple sensors, the system achieves adequate positioning precision for selection purposes while maintaining immunity to water and liquids.
Solution Approach 2:
The patent introduces a rigid surface layer as an intermediary between the user's finger and the inductive sensors. This rigid surface distributes and transmits force uniformly to the sensors below, enabling accurate force measurement and position determination while maintaining the water-resistant benefit of inductive sensing.
4Device complexity
If force sensors are placed in four corners for triangulation, then cost is reduced, but measurement precision for position determination decreases
Solution Approach 1:
The patent transitions from direct contact capacitive sensing to force-based inductive sensing, adding a mechanical dimension (force application through rigid surface) to the sensing mechanism. This dimensional change enables position determination through force triangulation from corner sensors, achieving adequate precision with fewer sensors.
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 system is resistant to water and liquids, cost-effective, and maintains functionality with user gloves, offering accurate selection and feedback in wet environments.
Implementation Method 1
a conductive or ferrite object adjacent to an inductive coil (for example on a pcb) moving closer to such coil and influencing the inductance of the coil
Data Source
AI summary
A touch screen or a touch non-display panel based on a user touch selection interface, based on inductive force sensing without requiring capacitive touch sensing, is described. This invention offers cost advantages and will operate well and unaffected with liquids on the surface or when a user wears gloves in comparison with capacitive touch solutions. The invention also teaches to combine the implementation of force sensing and haptic signal generation.