Capacitive Touch Sensor Uniform Threshold on Non-Flat Surfaces
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Solution Overview
Problem
Existing capacitive touch sensing technologies face challenges in maintaining a uniform threshold for touch detection on non-flat surfaces, leading to nonlinearity in analog capacitive touch sensing due to varying distances and dielectric constants across the touch pad.
Innovation Solution
A capacitive touch sensor layer is configured to provide a uniform capacitance threshold level by maintaining a substantially uniform distance and/or using a gradient of dielectric constants between the non-flat touch surface and the sensor layer, which can be achieved by bending the sensor layer to follow the surface shape and employing materials with varying dielectric constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a capacitive sensor layer is used on a non-flat touch surface, then touch detection capability is provided, but the capacitance threshold becomes non-uniform across different locations
Solution Approach 1:
The dielectric layer is designed with spatially varying dielectric constant values tailored to specific locations on the touch surface. Areas with larger distances between the touch surface and sensor layer use dielectric materials with higher dielectric constants, while areas with smaller distances use materials with lower dielectric constants. This local customization of dielectric properties compensates for the non-uniform geometry and achieves uniform capacitance threshold across the entire touch surface.
Solution Approach 2:
The invention changes the dielectric constant parameter of the material between the touch surface and sensor layer as a function of position. By selecting dielectric materials with different dielectric constants for different locations, the system compensates for geometric variations and maintains uniform capacitive coupling, thereby achieving consistent touch detection threshold across the non-flat surface.
2Shape
If the distance between touch surface and sensor layer varies across locations, then the touch surface can accommodate non-flat geometry, but signal nonlinearity occurs in capacitive touch sensing
Solution Approach 1:
The dielectric layer is designed with spatially varying dielectric constant values tailored to specific locations on the touch surface. Areas with larger distances between the touch surface and sensor layer use dielectric materials with higher dielectric constants, while areas with smaller distances use materials with lower dielectric constants. This local customization of dielectric properties compensates for the non-uniform geometry and achieves uniform capacitance threshold across the entire touch surface.
Solution Approach 2:
The invention employs composite dielectric structures consisting of multiple dielectric layers or regions with different dielectric constants. This composite approach allows the system to maintain non-flat touch surface geometry while compensating for distance variations through the combined effect of different dielectric materials, thereby achieving linear and uniform capacitive signal response.
3Adaptability or versatility
If overlaying materials and structures are non-flat, then design flexibility is increased, but uneven capacitive sensor signals are generated
Solution Approach 1:
The dielectric layer is designed with spatially varying dielectric constant values tailored to specific locations on the touch surface. Areas with larger distances between the touch surface and sensor layer use dielectric materials with higher dielectric constants, while areas with smaller distances use materials with lower dielectric constants. This local customization of dielectric properties compensates for the non-uniform geometry and achieves uniform capacitance threshold across the entire touch surface.
Solution Approach 2:
The invention changes the dielectric constant parameter of the material between the touch surface and sensor layer as a function of position. By selecting dielectric materials with different dielectric constants for different locations, the system compensates for geometric variations and maintains uniform capacitive coupling, thereby achieving consistent touch detection threshold across the non-flat surface.
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 approach ensures consistent touch detection across non-flat surfaces, eliminating signal nonlinearity and enhancing the accuracy of capacitive touch sensing by maintaining a uniform capacitance threshold level regardless of the touch location.
Implementation Method 1
monitoring the capacitance value between elements X and Y
Implementation Method 2
Charge pulses can be injected from a number of electrodes placed around the touch plane... These charge pulses generate electric field around the semi-conductive plane and the finger absorbs energy of some of the pulses
Data Source
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AI summary
The specification and drawings present a new apparatus and method for providing and using a uniform threshold for capacitive touch sensing in a user interface having a non-flat touch surface. The capacitive touch sensor can to provide a sensor signal using the uniform capacitance threshold level as a function of a location of an object (e.g., finger, stylus, etc.) on or near the non-flat touch surface of a user interface module using a substantially uniform distance between the non-flat touch surface and a capacitive touch sensor layer, and/or using a gradient of a dielectric constant of materials between the non-flat touch surface and the capacitive touch sensor layer according to a predetermined criterion.