Non-orthogonal Electrode Geometry for Touchscreen Signal Path Reduction
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Solution Overview
Problem
Touchscreen devices with orthogonal electrode arrangements face limitations in sensitivity due to longer signal path lengths, which can lead to reduced accuracy in detecting touch inputs and increased measurement errors.
Innovation Solution
Implementing non-orthogonal electrode geometries, such as U-drive and V-sense electrodes intersecting at acute angles, which reduce signal path lengths and maintain or improve sensitivity without increasing the number of drive channels, allowing for area-preserving shear transformations to preserve capacitance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If orthogonal electrode arrangements are used, then the device structure is simple and easy to manufacture, but the signal path length increases leading to reduced sensitivity and increased measurement errors
Solution Approach 1:
The patent applies asymmetry by transitioning from orthogonal (90-degree) electrode intersections to non-orthogonal electrode arrangements with acute angles. This asymmetric geometric transformation shortens the signal path length between intersecting electrodes, thereby improving touch detection sensitivity and reducing measurement errors while maintaining manufacturing feasibility
Solution Approach 2:
The patent changes the geometric parameter of electrode intersection angle from 90 degrees to an acute angle θ where 0° < θ ≤ 45°. This parameter modification directly reduces the signal path length and improves the sensitivity of touch detection without complicating the manufacturing process
2Measurement precision
If non-orthogonal electrodes are implemented, then touch sensitivity improves due to shorter signal path lengths, but the device complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the intersection angle of electrodes locally while maintaining the overall grid structure. Each electrode intersection adopts an acute angle θ to locally optimize signal path length and sensitivity, while the global electrode arrangement remains systematic and manageable
Solution Approach 2:
The patent introduces angular dimensionality by varying the intersection angle θ of electrodes. This dimensional change from fixed orthogonal intersections to variable acute angle intersections creates additional design freedom to optimize signal paths while maintaining structural regularity
3Measurement precision
If the number of drive channels is increased to improve sensitivity, then touch detection accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent changes the geometric parameter of electrode arrangement (intersection angle θ) to improve sensitivity without increasing the number of drive channels. By optimizing the acute angle between electrodes, the system achieves better touch detection accuracy while maintaining the same channel count, thereby avoiding increased device complexity and cost
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 enhances touch sensitivity by decreasing the signal time delay and measurement errors, while maintaining the same number of drive channels, thus improving the accuracy of touch input detection in touchscreen devices.
Implementation Method 1
Members of a subset of the P U-drive electrodes communicatively coupled to one of the N drive channels may intersect mutually exclusive sets of the V-sense electrodes. Based on a value of θ, signals corresponding to the drive signals traverse path lengths on the rectangular touch sensitive area that are less than W plus H.
Data Source
AI summary
Some embodiments include a touchscreen device (e.g., a projected capacitive sensor) with non-orthogonal U-drive and V-sense electrodes that intersect at an acute angle, θ. The touchscreen device includes a rectangular touch sensitive area with horizontal edge of length W and a vertical edge of length H. Some embodiments include a controller coupled to the touchscreen device that transmits signals via N drive channels, where N is an integer, where the N drive channels are communicatively coupled to P U-drive electrodes, and where P is an integer greater than or equal to N. Members of a subset of the P U-drive electrodes communicatively coupled to one of the N drive channels, intersect mutually exclusive sets of the V-sense electrodes. Motivated by signal-to-noise ratio considerations, values of acute angle, θ, are chosen such that signals corresponding to the drive signals traverse path lengths that are less than W plus H.