System and method for detecting locations of touches on a projected capacitive touch sensor
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Solution Overview
Problem
Projected capacitive touch sensors are prone to coordinate distortions due to electrical noise, leading to inaccurate touch location detection and increased production costs, especially in larger systems.
Innovation Solution
A projected capacitive touch sensor system with non-overlapping sets of electrodes, including horizontal and vertical sensing electrodes on a single layer substrate, where the controller detects signal levels to determine touch coordinates, reducing the number of electronic channels required and minimizing noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional projected capacitive touch sensors calculate coordinates based on measured capacitance, then touch location detection is achieved, but coordinate distortions occur due to electrical noise
Solution Approach 1:
The touch sensor divides the sensing area into multiple non-overlapping electrode sets, where each set independently detects touches in its specific region. This segmentation allows the system to identify touch locations through electrode set activation patterns rather than calculating coordinates from capacitance measurements, thereby eliminating noise-induced coordinate distortions while maintaining detection accuracy.
2Measurement precision
If multiple electrode layers or backgammon-type electrode patterns are used to detect touches, then touch detection capability is improved, but production costs increase
Solution Approach 1:
The sensor uses multiple non-overlapping electrode sets arranged in a single layer, with each set dedicated to detecting touches in its specific region. This approach achieves comprehensive touch detection coverage without requiring complex multi-layer structures or expensive backgammon-type patterns, thereby reducing manufacturing costs while maintaining detection capability.
Solution Approach 2:
Each electrode set is optimized for its specific sensing region with locally adapted electrode configurations. This allows the system to achieve high detection precision in each local area using simple single-layer electrode structures, avoiding the need for expensive uniform complex patterns across the entire sensor surface.
3Ease of operation
If conventional coordinate calculation methods are used, then touch location is determined, but system complexity and electronic channel requirements increase
Solution Approach 1:
The sensor divides the touch sensing area into multiple non-overlapping electrode sets, where each set independently detects touches in its region. The controller identifies touch locations by determining which electrode sets are activated rather than calculating coordinates through complex algorithms, thereby reducing electronic channel requirements and system complexity while maintaining ease of operation.
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 solution enhances noise tolerance and reduces production costs by accurately determining touch coordinates with fewer electronic channels, improving the reliability and efficiency of touch sensor systems.
Implementation Method 1
When a user's finger touches the outer surface at a location corresponding to a desired selection displayed on the display device, 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 includes a substrate and sets of electrodes coupled to corresponding areas of the substrate. The areas are non-overlapping with respect to each other. The sets of electrodes include a horizontal sensing electrode that extends along a height of a first column within the area and vertical sensing electrodes that extend partially along the height of at least one column within the area. The at least one column includes at least two vertical sensing electrodes that are physically separate with respect to each other and electrically connected to each other.