Touch Sensor Trace Width Matching for Uniform Channel Impedance
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Solution Overview
Problem
Existing touch sensors, particularly capacitive and electromagnetic touch sensors, suffer from impedance inconsistencies between channels, leading to non-linear touch responses, reduced accuracy, and uneven signal-to-noise ratios, especially in hybrid input scenarios.
Innovation Solution
The touch sensor design includes a non-touch area with signal traces that are differentiated based on length, with widths adjusted to match resistance and capacitance thresholds, ensuring uniform impedance and capacitance across channels, thereby improving linearity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If signal traces with different lengths are used to connect touch channels, then the coverage area increases, but the impedance inconsistency between channels increases
Solution Approach 1:
The patent applies local quality by adjusting the width of signal traces based on their individual lengths. Longer signal traces are assigned greater widths to compensate for their higher resistance, while shorter traces have narrower widths. This localized differentiation of trace geometry ensures that all touch channels achieve matched impedance values despite varying lengths, resolving the contradiction between coverage area and impedance consistency.
2Manufacturing precision
If signal trace widths are adjusted to match impedance, then the impedance consistency improves, but the manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by systematically varying the width parameter of signal traces based on their length parameters. This creates a scalable design approach where impedance matching is achieved through controlled geometric parameter adjustments rather than complex circuit designs. The method maintains manufacturing simplicity by using straightforward width modifications that can be integrated into standard PCB fabrication processes.
3Area of stationary object
If longer signal traces are used, then the touch channel coverage increases, but the resistance increases
Solution Approach 1:
The patent applies the anti-weight principle by using increased trace width as a compensating factor against the increased resistance from longer trace lengths. The greater width provides lower resistance that counterbalances the higher resistance inherent in longer traces, ensuring that all channels maintain matched impedance values. This compensation mechanism preserves signal quality across the extended coverage area.
Data Source
AI summary
The present disclosure provides a touch sensor which includes a touch area including at least a plurality of first touch channels, and a non-touch area located at a side of the touch area. The non-touch area includes at least a plurality of first signal traces. The first signal traces connected to the first touch channels are different from each other. A first resistance mismatch degree between first resistances corresponding to the plurality of first touch channels is less than or equal to a resistance mismatch degree threshold, and/or a first capacitance mismatch degree between first capacitances corresponding to the plurality of first touch channels is less than or equal to a capacitance mismatch degree threshold.