Profiled Capacitive Electrode for Uniform Touch-Force Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive touch-on-surface (ToS) sensing technologies in mobile devices face challenges in providing uniform touch-force sensitivity across the screen, as touch-force deflection is non-uniform due to varying deflection patterns near the center and edges, leading to inconsistent input detection.
Innovation Solution
A profiled capacitive sensor electrode with a non-uniform density profile, where the density is lower near the center and higher near the edges, is used in conjunction with elastomeric spacer elements, ensuring uniform sensitivity by compressing these elements and reducing the distance between the electrode and ground plates, allowing for consistent touch-force sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional uniform capacitive electrode is used, then the device structure is simple, but the touch-force sensitivity is non-uniform across the screen
Solution Approach 1:
The capacitive electrode is designed with a non-uniform density profile where the conductive area density varies across different regions of the electrode. Specifically, the density is lower near the center and higher near the edges, creating local quality variations that compensate for the non-uniform deflection characteristics of the display panel, thereby achieving uniform touch-force sensitivity across the screen.
2Measurement precision
If the capacitive electrode density is increased near the edges, then edge sensitivity improves, but the overall electrode complexity increases
Solution Approach 1:
The electrode design implements parameter changes in the conductive area density distribution. By varying the density parameter across different spatial locations (lower density at center, higher density at edges), the electrode compensates for position-dependent deflection characteristics, improving edge detection accuracy while maintaining manufacturability through standard fabrication techniques.
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
This configuration achieves substantially uniform touch-force sensitivity across the capacitive electrode, enhancing the accuracy and reliability of touch-force detection without the need for multiple sensors.
Implementation Method 1
Capacitive TOS sensing is based on a capacitive electrode disposed behind and spaced from the TOS display surface, and driven to project an electric sensing field in the direction of the TOS display surface, so that touch input through the TOS display surface is detected as a changed in capacitance measured by the capacitive electrode.
Implementation Method 2
the capacitive sensor electrode spaced from the ground plates by respective elastomeric insulator spacer elements, wherein the profiled capacitive sensor electrode can be configured with a density profile such that sensitivity to a touch-force deflection of the profiled capacitive sensor electrode is substantially uniform across the electrode
Data Source
AI summary
A device (such as for mobile communications) including a capacitive touch-on-surface (ToS) display adapted for capacitive touch-force sensing. A ToS capacitive sensor includes a profiled capacitive sensor electrode, intermediate and spaced from parallel ground plates by elastomeric insulator/dielectric spacer elements. The profiled capacitive sensor electrode has a non-uniform density profile that is relatively lower near a center of the electrode, and relatively higher near edges of the electrode, for example, equalizing touch-force sensitivity such that sensitivity to a touch-force deflection is substantially uniform across the profiled capacitive electrode. Capacitive sensor electronics coupled to the profiled capacitive sensor electrode measures a touch-force deflection of the ToS display panel based on a resulting touch-force deflection of the profiled capacitive electrode, such that the combined distance between the profiled capacitive sensor electrode and the ground electrodes is reduced by compression of the elastomeric spacer elements.