Projected Capacitive Touch Sensing With Deformable Dielectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current projected capacitive touch sensing technologies face challenges in accurately detecting touch inputs and determining the location and force of contact due to interference from external disturbances and the need for complex signal processing, especially when dealing with non-conductive inputs like styluses.
Innovation Solution
A projected capacitive touch sensing system is implemented using a common plate electrode and patterned capacitive touch sensing electrodes spaced apart, with a deformable dielectric material between them, allowing for capacitance changes to be sensed electronically. This system includes a flexible top substrate and a rigid bottom substrate, where the top substrate bends upon touch, altering the distance between electrodes and enabling precise capacitance measurement, and features a diamond pattern layout for electrodes to minimize interference and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional projected capacitive touch sensing is used, then the system can detect touch inputs, but external disturbances interfere with accurate detection and complex signal processing is required
Solution Approach 1:
The electrode structure is segmented into multiple interdigitated fingers rather than a single continuous electrode. This segmentation creates distinct capacitive zones that can be independently measured, allowing the system to differentiate between actual touch inputs and external disturbances by analyzing capacitance patterns across multiple segments.
Solution Approach 2:
The dielectric material properties are optimized locally between each pair of interdigitated electrode fingers to enhance sensitivity to touch while maintaining immunity to external disturbances. The local capacitance structure is designed to maximize the signal from actual touch contacts while minimizing pickup from external electromagnetic interference.
2Adaptability or versatility
If complex signal processing is used to handle non-conductive inputs, then detection capability improves, but system complexity increases
Solution Approach 1:
The system replaces complex signal processing algorithms with a simplified capacitive measurement approach using interdigitated electrodes. The physical electrode geometry itself provides the discrimination capability needed to detect non-conductive inputs, eliminating the need for complex computational processing while maintaining versatility in detecting different input types.
3Measurement precision
If closely spaced electrodes are used to increase sensitivity, then capacitance change detection improves, but external interference increases
Solution Approach 1:
The electrodes are segmented into multiple interdigitated fingers with alternating polarity connections. This segmentation creates a differential measurement system where external electromagnetic interference affects all fingers equally and cancels out, while actual touch inputs create localized capacitance changes that are detected as differential signals between adjacent fingers.
Solution Approach 2:
The electrode arrangement transitions from simple parallel plates to a three-dimensional interdigitated structure extending in multiple directions. This dimensional change creates overlapping electric fields that enhance sensitivity to touch while the symmetric geometry provides inherent rejection of external interference through differential measurement 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
The system effectively detects touch inputs and determines their location and force with high accuracy, even with non-conductive inputs, while minimizing external interference and maintaining a clear display image, by utilizing the deformable dielectric material and diamond pattern layout to accurately measure capacitance changes.
Implementation Method 1
The capacitance between a pair of adjacent patterned capacitive touch sensing electrodes changes based on changes in a distance between the common plate electrode and the pair of adjacent patterned capacitive touch sensing electrodes
Implementation Method 2
deformable dielectric material positioned between the common plate electrode and the patterned electrodes
Data Source
AI summary
Methods, systems, and apparatus relate to touch sensors that are configured to measure input applied to the sensor from a user. Some implementations involve the measurement of changes in capacitance between pairs of adjacent patterned electrodes to detect input at a touch sensor.