Capacitive Sense Array Edge Accuracy via Non-Homogenous Pitch
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Solution Overview
Problem
Conventional capacitive touch screens experience significant position tracking errors near the edges due to incomplete signal profiles when a conductive object approaches, leading to reduced accuracy compared to the center area.
Innovation Solution
A capacitive sense array with non-homogenous pitches, where the width and spacing of sense elements vary, particularly with smaller pitches and widths at the edges to improve signal profile granularity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If homogenous width sense elements are used across the panel, then manufacturing is simplified and device complexity is reduced, but position tracking accuracy deteriorates at the edges
Solution Approach 1:
The patent applies local quality by varying the pitch and width of sense elements based on their location within the touch panel. Edge regions utilize smaller pitches and narrower sense element widths compared to center regions, optimizing measurement precision locally at edges while maintaining manufacturing feasibility through a systematic gradient transition across the panel.
Solution Approach 2:
The patent implements parameter changes by systematically varying the pitch and width parameters of sense elements across different regions of the panel. This creates a non-homogenous configuration where edge regions have smaller pitch values and narrower widths, directly addressing the accuracy deterioration problem while maintaining a manufacturable gradient transition.
2Measurement precision
If sense element pitch is reduced at edges to improve signal profile granularity, then edge accuracy improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing different pitch values for edge regions versus center regions. Edge sense elements use smaller pitches to capture finer signal profile granularity, while center regions maintain larger pitches. This localized optimization improves edge accuracy without requiring complete redesign of the entire sense element array.
Solution Approach 2:
The patent segments the touch panel into distinct regions (edge regions and center regions) with different sense element configurations. This segmentation allows independent optimization of each region's parameters, enabling smaller pitches at edges for improved accuracy while maintaining larger pitches in center regions to manage overall device complexity.
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 configuration enhances edge accuracy by providing a more complete signal profile, reducing systematic centroid offset and improving overall position tracking precision at the edges of the touch screen.
Implementation Method 1
When a conductive object, such as a finger, comes in contact or close proximity with the touch-sensing surface, the capacitance of one or more capacitive touch sense elements changes.
Implementation Method 2
The transmission and receive sense elements in the N×M sense element matrix are arranged so that each of the transmission sense elements intersects each of the receive sense elements. Thus, each transmission sense element is capacitively coupled with each of the receive sense elements.
Data Source
AI summary
A capacitive sense array configured to improve edge accuracy in detecting a presence of a conductive object is described. In one embodiment, a capacitive sense array includes at least a first set of sense elements having non-homogenous pitches disposes in a first longitudinal axis of the capacitive sense array. The pitch includes width of the sense elements and spacing between the sense elements.