Sense Electrode Crossbar Width Optimization for Charge Transfer
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Solution Overview
Problem
Capacitive touchscreens face performance issues due to long charge transfer times caused by high resistance in electrode connections, which can slow down touchscreen operation.
Innovation Solution
The electrode layout is optimized by varying the width of crossbars transverse to drive electrodes, with wider crossbars farther from connection lines to reduce resistance and maintain or improve charge transfer times, ensuring efficient charge transfer to sense capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform width crossbars are used in sense electrodes, then manufacturing is simpler, but charge transfer time increases due to high resistance in distant connection lines
Solution Approach 1:
The patent applies local quality by varying the width of crossbars based on their position relative to connection lines. Crossbars farther from connection lines are made wider to reduce resistance and compensate for longer charge transfer paths, while crossbars closer to connection lines remain narrower. This localized adjustment optimizes charge transfer time without uniformly increasing complexity across the entire electrode structure.
2Loss of time
If wider crossbars are used throughout the sense electrode, then charge transfer time is reduced, but the overall thickness and material usage increase
Solution Approach 1:
The patent implements local quality by strategically widening only those crossbars that are farthest from connection lines, where the resistance and charge transfer time are most problematic. This localized approach reduces charge transfer time for the most affected regions without unnecessarily increasing the thickness or material usage across the entire touchscreen structure.
3Reliability
If flooded drive electrode pattern is used, then shielding from electric field interference is improved, but resistance to connection lines increases
Solution Approach 1:
The patent resolves this contradiction by maintaining the flooded drive electrode pattern for reliable shielding while locally adjusting crossbar widths to compensate for increased resistance. The wider crossbars at distant positions offset the resistance introduced by the comprehensive flooded pattern, ensuring both shielding effectiveness and acceptable charge transfer times are achieved simultaneously.
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 reduces the overall thickness of the touchscreen and maintains or improves charge transfer times, enhancing the operational speed and efficiency of capacitive touchscreens.
Implementation Method 1
The resistance to connection lines from portions of the crossbar electrode farthest from connection lines is greater than the resistance to connection lines from portions of the crossbars closer to the connection lines
Implementation Method 2
The electronics may contain sense circuitry having a sense capacitor. The sense circuitry operate to accommodate a worst case charge transfer time, having resistive and capacitive components, to allow sufficient charge to transfer from the drive electrodes through the sense electrodes to the sense capacitor
Data Source
AI summary
A touch sensitive device includes a plurality of sense electrodes arranged in a pattern to receive charge from drive electrodes. The pattern of sense electrodes has extreme portions having worst case charge transfer times, wherein the worst case charge transfer time at multiple extreme portions is substantially equal.