Projected Capacitive Touch Sensor Noise Resilience
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Solution Overview
Problem
Conventional projected capacitive touch sensors face challenges in accurately detecting touch locations in electrically noisy environments, leading to coordinate distortions and increased production costs, especially for larger systems, and struggle with simultaneous touch detection.
Innovation Solution
A touch sensor system with a substrate having non-overlapping areas of detection electrodes, including a horizontal detection electrode and vertically isolated pairs of detection electrodes, measures mutual capacitance or impedance to determine touch locations, reducing noise susceptibility and electronic channel requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional capacitance measurement algorithms are used to detect touch locations, then the system can operate with simpler electrode configurations, but measurement accuracy deteriorates in electrically noisy environments
Solution Approach 1:
The touch sensor surface is divided into multiple non-overlapping detection areas, each with its own set of detection electrodes. This segmentation allows independent measurement in each area, reducing the impact of electrical noise from other regions and improving overall measurement accuracy without requiring complex global electrode configurations.
Solution Approach 2:
Each detection area is equipped with locally-optimized electrode configurations tailored to specific measurement requirements. The first detection area uses a configuration optimized for certain touch types, while the second area uses a different configuration for other touch types, allowing each region to operate with optimal local characteristics rather than a single complex global configuration.
2Adaptability or versatility
If multiple electrode layers are used to support simultaneous touches, then multi-touch capability is improved, but manufacturing cost increases
Solution Approach 1:
Instead of adding more electrode layers in the vertical dimension to detect multiple touches, the invention uses multiple detection areas arranged in the horizontal plane. Each area can independently detect touches, enabling multi-touch capability through spatial distribution rather than layer stacking, thereby reducing manufacturing complexity and cost.
3Device complexity
If backgammon-type electrode patterns are used for coordinate calculation, then single-layer simplicity is maintained, but noise susceptibility increases significantly
Solution Approach 1:
The sensor is divided into multiple detection areas with separate electrode sets, isolating the measurement processes. This segmentation prevents noise from affecting all measurements simultaneously and allows each area to maintain simple electrode patterns while achieving overall noise resilience through independent operation.
4Measurement precision
If more electronic channels are used to reduce noise effects, then measurement accuracy improves, but production cost increases
Solution Approach 1:
By dividing the sensor into multiple detection areas with independent electrode sets, the system achieves noise-resistant measurements without requiring excessive electronic channels. Each area processes measurements independently, allowing the use of fewer channels per area while maintaining overall accuracy, thus reducing production costs.
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 enhances noise tolerance and reduces production costs by accurately determining touch locations with fewer electronic channels, supporting multiple simultaneous touches while minimizing the effects of electrical noise.
Implementation Method 1
the touch sensor system senses a change in capacitance associated with one or more of the electrodes
Data Source
AI summary
A projected capacitive touch sensor system includes a substrate that defines a plurality of non-overlapping areas. Each non-overlapping area includes a plurality of detection electrodes arranged in non-overlapping columns. The columns include a horizontal detection electrode that extends along substantially an entire height of a first column, and at least a second column of at least two vertical detection electrodes that are electrically isolated from one another. The system further includes a measuring circuit configured to measure a mutual capacitance between the horizontal detection electrode and each of the at least two vertical detection electrodes in a given area. A processing logic circuit of the system is configured to determine horizontal detection electrode and vertical detection electrode combinations that have a changed mutual capacitance. The processing logic is also configured to determine the touch location based on a location of the determined horizontal detection electrode and vertical electrode combinations.