Touch Panel Passivation Layer Refractive Index Matching
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Solution Overview
Problem
Conventional touch panels suffer from visible etching lines and blurred images due to refractive index differences between transparent conductive and etched areas, leading to poor display quality, and existing solutions complicate the manufacturing process and increase costs.
Innovation Solution
A touch panel with a conductive layer covered by a passivation layer containing transparent metallic oxide with a refractive index higher than 1.8, which matches the refractive index of the transparent electrodes, reducing the visibility of etching lines and improving optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent conductive layer with electrode pattern is formed on a transparent substrate, then the touch panel can function as a capacitive touch panel, but the etching lines become visible due to refractive index difference between ITO area and etched area
Solution Approach 1:
A passivation layer is introduced as an intermediary between the transparent conductive layer and the outer protective layer. This passivation layer has a refractive index that bridges the gap between the ITO area (higher refractive index) and the etched area (lower refractive index), reducing the visible etching lines while maintaining the capacitive touch function
Solution Approach 2:
The refractive index parameter of the passivation layer is specifically controlled to be between 1.4 and 1.6, which is higher than the substrate glass (1.5-1.7) but lower than the ITO layer. This parameter optimization makes the etching lines invisible while preserving the touch panel's electrical functionality
2Object-affected harmful factors
If nanoparticles layer with high refractive index is coated onto the transparent substrate to hide etching lines, then the etching lines become invisible, but the optical transmission is reduced and haze is enlarged
Solution Approach 1:
Instead of using nanoparticles with very high refractive index (which cause optical degradation), the patent uses a passivation layer with a moderately high refractive index (1.4-1.6). This parameter change achieves the goal of making etching lines invisible while maintaining good optical transmission and minimizing haze
Solution Approach 2:
The passivation layer is formed as a composite structure combining the transparent substrate, the transparent conductive layer with ITO, and the passivation layer with optimized refractive index. This composite structure achieves both the hiding of etching lines and maintenance of optical performance
3Strength
If nanoparticles layer is covered with protecting layer made of SiO2 or organic polymer and baked under high temperature, then the nanoparticles layer gains adhesive power and rigidity, but the manufacturing process is prolonged and cost increases
Solution Approach 1:
The patent extracts and eliminates the complex multi-step process of coating nanoparticles, adding protecting layers, and high-temperature baking. Instead, it directly forms a passivation layer with optimized refractive index that provides both the visual benefit of hiding etching lines and the structural benefit of adhesive power and rigidity in a single step
Solution Approach 2:
The passivation layer is designed as a simple, cost-effective single-layer structure that replaces the complex multi-layer nanoparticle and protecting layer system. This simplified structure reduces manufacturing complexity and cost while achieving the same functional goals
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
The solution effectively makes etching lines invisible, enhancing the optical performance and reducing manufacturing complexity and costs, while maintaining the high sensitivity and low cost of capacitive touch panels.
Implementation Method 1
Due to the difference between refractive index in the two areas, the etching line dividing ITO area and etched area are visible to users
Data Source
AI summary
The present invention discloses a touch panel and a method of manufacturing a touch panel, to reduce the visibility of the transparent etching line of the transparent electrodes on the touch panel. The touch panel comprises a plurality of transparent electrode disposed distantly on the transparent conductive layer and the passivation layer of a transparent substrate, where the passivation layer covering the transparent conductive layer, to make the refractive index of the passivation layer and the transparent electrodes match with each other. Oxide with high refractive index added in the passivation material is filled in the etched area of the transparent conductive layer, so that the optical refractive index of the etched area and ITO area on transparent conductive layer become closer, and the difference in refractive index curve between ITO area and etched area is reduced, therefore, the effect of making the transparent electrode pattern is achieved.