Patterned Electrode Wiring for Touch Device Signal Accuracy
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Solution Overview
Problem
Conventional touch devices with single electrode layers suffer from poor touch input sensing due to high surface resistance of materials like indium tin oxide, limiting their ability to accurately detect touch inputs.
Innovation Solution
A touch device design featuring patterned electrode sets with distinct wiring line configurations, including longer and shorter groups with varying diameters and gaps, to reduce resistance and ensure consistent non-sensing region widths, enhancing touch-sensing signal accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a single electrode layer is used to simplify the structure and meet slim device requirements, then device thickness and weight are reduced, but touch input sensing ability deteriorates due to high surface resistance of electrode materials
Solution Approach 1:
The single electrode layer is segmented into multiple patterned electrode sets, each comprising a driving electrode and multiple sensing electrodes arranged in specific patterns (comb-shaped, E-shaped, fish-bone shape). This segmentation increases the effective sensing area and reduces the impact of high surface resistance by distributing the sensing function across multiple electrode regions.
Solution Approach 2:
Different regions of the electrode layer are designed with different properties: driving electrodes have specific patterns for signal generation, while sensing electrodes have varied shapes and wiring line configurations (different diameters and lengths) optimized for their local sensing requirements. The wiring lines are designed with varying diameters to compensate for length differences and maintain uniform electrical characteristics across the touch surface.
2Area of stationary object
If wiring lines with different lengths are used to connect sensing electrodes, then coverage area is increased, but resistance increases and signal accuracy deteriorates
Solution Approach 1:
Wiring lines are designed with non-uniform properties: longer wiring lines have greater diameters than shorter ones. This local variation in wiring line diameter compensates for the increased resistance in longer lines, ensuring that all sensing electrodes maintain comparable electrical characteristics and signal quality regardless of their position in the sensing array.
Data Source
AI summary
A touch device includes a circuit board, a substrate and a touch-sensing layer. The touch-sensing layer including patterned electrode sets is disposed on the substrate. Each patterned electrode set includes a driving electrode connected to the circuit board and sensing electrodes having wiring lines connected to the circuit board. The wiring lines of each patterned electrode set include first and second groups. The length for one of the wiring lines in the first group is greater than the length for one of the wiring lines in the second group. Diameters of the wiring lines in the first group are greater than diameters of the wiring lines in the second group. The diameter of the longer wiring line is greater than the diameter of the shorter wiring line, in the first group. The diameters in the second group are identical. The total widths of the first and second groups are equal.