Capacitive Touch Area Isolation via Conductive Material Segmentation
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Solution Overview
Problem
Capacitive touch sensors face interference due to conductive materials on device surfaces, which can capacitively couple underlying electrodes, reducing system sensitivity and functionality.
Innovation Solution
The use of a conductive secondary process followed by strategic removal of conductive material in boundary areas to isolate capacitive touch areas, allowing for the application of decorative or functional conductive coatings that do not compromise capacitive sensing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conductive material is deposited on the device surface for cosmetic purposes or to highlight sensor locations, then the device appearance and sensor visibility are improved, but capacitive coupling between underlying electrodes increases, reducing sensing sensitivity
Solution Approach 1:
The conductive material deposition process is segmented into multiple stages: initial deposition, selective removal in boundary areas, and controlled re-deposition. This segmentation allows the conductive material to be present on the device surface for cosmetic purposes while preventing capacitive coupling between adjacent electrodes by removing material from critical boundary regions.
Solution Approach 2:
The conductive material distribution is made non-uniform through selective removal in boundary areas between electrodes. This creates local variations in conductive material presence: areas over electrodes retain conductive material for appearance, while boundary areas have reduced or removed conductive material to prevent coupling, thus achieving different local qualities in different regions.
2Loss of information
If conductive material is used to highlight the location of underlying sensors, then sensor visibility is improved, but capacitive coupling between adjacent sensors increases, violating conductive separation requirements
Solution Approach 1:
The conductive material layer is segmented into discrete regions through selective removal processes. Boundary areas between sensor locations have conductive material removed or reduced, creating electrical separation zones that prevent capacitive coupling, while conductive material remains present over sensor areas to provide visual highlighting.
Solution Approach 2:
The conductive material serves as an intermediary element that can simultaneously provide visual highlighting and electrical separation. By controlling the spatial distribution of this intermediary through selective deposition and removal, it becomes possible to achieve both visual visibility and electrical isolation functions.
3Shape
If a continuous conductive coating is applied over the device surface, then cosmetic appearance is improved, but capacitive touch sensor performance deteriorates due to unwanted coupling between electrodes
Solution Approach 1:
The continuous conductive coating is segmented into discrete conductive regions through selective removal in boundary areas. This segmentation maintains the cosmetic appearance benefits of conductive material presence while eliminating the harmful capacitive coupling effects by creating gaps or reduced-conductivity zones between sensor electrodes.
Solution Approach 2:
The conductive coating is transformed from uniform to non-uniform with different local properties: areas over electrodes maintain full conductive material coverage for appearance, while boundary regions have reduced or removed conductive material to prevent coupling, achieving local quality differentiation that resolves the contradiction.
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 enables the use of conductive surface materials as floating electrodes, enhancing capacitive touch performance while maintaining the device's appearance and functionality, preventing undesirable capacitive coupling between sensors.
Implementation Method 1
Capacitive touch sensors operate by monitoring the change in capacitance above a parasitic capacitance background when a conductor such as the user finger comes in close proximity to or in contact with a sense electrode
Implementation Method 2
Electrically separate in particular means that capacitive coupling is low as this reduces the system sensitivity
Data Source
AI summary
Methods and apparatuses for capacitive sensing are disclosed. In one example, a conductive material is arranged on the mobile device exterior surface outside of a capacitive coupling area undesirably coupling underlying electrodes beneath the surface.