Interleaved Capacitive Sense Array Layout for Dead Zone Accuracy
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Solution Overview
Problem
Capacitive touch sensing devices face accuracy issues due to signal degradation and dead zones in single-layer Indium Tin Oxide (ITO) capacitive sense arrays, leading to errors in centroid determination and overall functionality.
Innovation Solution
The capacitive sense array design includes a first set of sense elements with sub-sections that straddle those of a second set, eliminating the dead zone area by shifting and interleaving sub-sections, thereby improving signal consistency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single layer ITO stack-up is used to reduce cost, then manufacturing cost is reduced, but accuracy deteriorates due to dead zone areas causing signal degradation
Solution Approach 1:
The patent divides the sense elements into multiple independent sets (first set and second set of sense elements) that are interleaved with each other. Each set can be independently controlled and read, allowing the system to segment the sensing function across multiple element groups while using a single ITO layer, thereby maintaining cost efficiency while improving signal quality and eliminating dead zones.
Solution Approach 2:
The patent introduces a new dimension of sensing by adding multiple sets of sense elements in an interleaved configuration rather than simply increasing the density within a single set. This dimensional arrangement allows overlapping sensing zones that eliminate dead areas while maintaining the single-layer structure, resolving the contradiction between cost and accuracy.
2Device complexity
If traditional aligned sense element pairs are used, then device complexity is reduced, but accuracy deteriorates due to dead zone areas causing periodic errors in centroid determination
Solution Approach 1:
The patent employs asymmetric interleaving where the first and second sets of sense elements are offset relative to each other in a non-uniform pattern. This asymmetric arrangement ensures that dead zones from one set are covered by the overlapping sensing areas of the other set, eliminating periodic errors in centroid determination while adding only moderate complexity to the element arrangement.
Solution Approach 2:
The patent pre-positions multiple sets of sense elements in an interleaved configuration before operation, where the geometric arrangement itself is designed to eliminate dead zones. This preliminary structural arrangement ensures that signal coverage is continuous across the entire sensing area, preventing accuracy issues before they occur during actual touch detection.
3Area of stationary object
If sense elements are densely packed to improve coverage, then area coverage is improved, but accuracy deteriorates due to increased dead zone interference and signal inconsistency
Solution Approach 1:
The patent merges the sensing functions of multiple interleaved sets of sense elements, where the sensing zones of different sets overlap and combine to provide continuous coverage. This merging approach ensures that every area of the sense array is covered by at least one active sensing element from an appropriate set, eliminating dead zones and ensuring signal consistency across the entire coverage area.
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 design enhances the accuracy of conductive object detection by providing a consistent signal profile across the capacitive sense array, reducing periodic errors and improving centroid determination.
Implementation Method 1
A mutual capacitance between each row and the first set of sense elements is measured. A mutual capacitance between each row and the second set of sense elements is also measured.
Implementation Method 2
A mutual capacitance between each row and the first set of sense elements is measured. A mutual capacitance between each row and the second set of sense elements is also measured.
Data Source
AI summary
A capacitive sense array configured to improve accuracy in detecting a presence of a conductive object is described. In one embodiment the capacitive sense array includes a first set of sense elements including a plurality of sub-sections and a second set of sense elements including a plurality of sub-sections such that the plurality of sub-sections of one sense element of the first set straddle at least one of the plurality of sub-sections of at least two of the sense elements of the second set. The straddle as defined in the present invention includes shifting and interleaving sub-section of one sense element with the sub-sections of at least two sense elements adjacent to the one sense element.