Touch Sensor Compensation Electrodes Reduce Resistance
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Solution Overview
Problem
Current touch sensors face challenges in achieving high resolution while maintaining sensitivity and transmittance, particularly as the dimension and pitch of sensing electrodes decrease, leading to increased resistance and degraded performance.
Innovation Solution
The implementation of a touch sensor design featuring semi-transparent sensing electrodes with a stack structure of transparent conductive oxide and metal layers, along with compensation electrodes that entirely cover the sensing electrodes, acting as bridge electrodes to reduce resistance and enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the critical dimension and pitch of sensing electrodes are decreased to increase electrode density for high resolution, then the resolution is improved, but the resistance of each sensing electrode is drastically increased and sensitivity is degraded
Solution Approach 1:
The patent merges the sensing electrode and compensation electrode into a unified structure where the compensation electrode is formed on top of the sensing electrode. This integration allows the sensing electrode to maintain its small dimensions for high resolution while the compensation electrode provides additional conductive area to reduce overall resistance, thereby maintaining sensitivity despite the reduced electrode size.
Solution Approach 2:
The patent employs a composite electrode structure consisting of multiple material layers including transparent conductive oxide (TCO) layers and metal layers. This composite structure combines the advantages of different materials: TCO provides transparency and basic conductivity, while metal layers provide enhanced conductivity with lower resistance, thus maintaining sensitivity even when electrode dimensions are reduced for high resolution.
2Measurement precision
If the critical dimension and pitch of sensing electrodes are decreased to increase electrode density for high resolution, then the resolution is improved, but the transmittance of the touch sensor is deteriorated
Solution Approach 1:
The patent applies local quality by using different materials with different optical properties in different parts of the electrode structure. The TCO layers provide good transmittance, while the metal layers (which can be patterned or used in thinner sections) provide conductivity. This localized material selection allows the electrode to maintain high transmittance in critical viewing areas while still providing sufficient conductivity for sensing resolution.
Solution Approach 2:
The composite electrode structure using TCO and metal layers allows optimization of both optical and electrical properties. The TCO layers maintain high transmittance for display visibility, while the metal layers provide the necessary conductivity. This composite approach enables high resolution sensing without significantly compromising transmittance, as each material contributes its superior property to the overall structure.
3Reliability
If the electrode area is increased to reduce resistance, then the sensitivity is improved, but the resolution is degraded
Solution Approach 1:
The patent resolves this contradiction by transitioning from a two-dimensional electrode layout to a three-dimensional structure. The sensing electrode maintains its small planar dimensions for high resolution, while the compensation electrode is stacked vertically on top, adding a third dimension. This vertical stacking increases the effective conductive area and reduces resistance without expanding the horizontal footprint that would degrade resolution.
Solution Approach 2:
By merging the sensing and compensation electrodes into a stacked configuration, the patent enables the sensing electrode to remain small for high resolution while the combined structure provides increased total conductive area. The compensation electrode's additional area contributes to lower resistance and improved sensitivity, achieving both goals simultaneously through structural integration rather than lateral expansion.
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 enables high-resolution touch sensing with reduced resistance, maintaining sensitivity and transmittance, suitable for applications like fingerprint sensors, by controlling electrode pitch and capacitance.
Implementation Method 1
first sensing electrodes arranged on the base layer along a first direction; second sensing electrodes arranged on the base layer along a second direction
Implementation Method 2
the first sensing electrodes and the second sensing electrodes include a stack structure of a transparent conductive oxide layer and a metal layer
Implementation Method 3
first compensation electrodes on the first sensing electrodes, the first compensation electrodes entirely covering each of the first sensing electrodes in a plan view; and second compensation electrodes on the second sensing electrodes, the second compensation electrodes entirely covering each of the second sensing electrodes in a plan view
Data Source
AI summary
A touch sensor includes a base layer, first sensing electrodes arranged on the base layer along a first direction, second sensing electrodes arranged on the base layer along a second direction, first compensation electrodes on the first sensing electrodes, and second compensation electrodes on the second sensing electrodes. The first compensation electrodes entirely cover each of the first sensing electrodes in a plan view, and the second compensation entirely cover each of the second sensing electrodes in a plan view.