Laminated Touch Panel Wiring for Low Reflection and Resistance
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Solution Overview
Problem
Existing touch panel structures face challenges in achieving low resistance and low reflection for outdoor use without degrading performance, particularly due to issues with transparent conductive films, metal wiring line damage, and design restrictions when integrating with color filters.
Innovation Solution
A touch panel structure with laminated wiring lines formed by stacking a low resistance conductive film, a low reflection film, and a transparent film, covered by an interlayer insulating film and protected by a conductive film, allowing for low resistance and low reflection without damaging the color filter layer during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transparent conductive film with relatively high resistance is used as wiring line in display part, then low reflection to incident light and high transmission to light from light source are achieved, but electrical resistance is high which affects responsiveness and sensitivity
Solution Approach 1:
The patent uses a composite wiring structure combining a transparent conductive film layer and a metal film layer. The transparent conductive film (e.g., ITO) provides low reflection and high light transmission, while the metal film (e.g., aluminum) provides low electrical resistance. This composite structure achieves both optical and electrical performance requirements simultaneously.
Solution Approach 2:
The metal film layer serves multiple functions: it acts as a low-resistance conductor for electrical signals and as a reflective layer to reduce incident light reflection. The transparent conductive film simultaneously provides light transmission and electrical conduction. This multi-functional design resolves the contradiction between optical and electrical requirements.
2Reliability
If a metal film with low resistance is used as wiring line, then electrical resistance is low improving responsiveness, but reflection to incident light increases reducing display visibility
Solution Approach 1:
The patent combines a metal film layer (for low resistance) with a transparent conductive film layer (for low reflection). The metal film provides excellent electrical conductivity while the transparent conductive film overlay reduces incident light reflection, achieving both electrical and optical performance.
Solution Approach 2:
The metal film is strategically positioned in specific regions (such as peripheral areas or specific wiring paths) where low resistance is critical, while the transparent conductive film covers areas requiring low reflection. This localized quality assignment optimizes both electrical and optical characteristics.
3Length of stationary object
If touch panel is formed on first main surface opposite to color filter on same substrate, then module thickness is reduced, but metal connection terminal part is damaged by alkaline developer during color filter formation
Solution Approach 1:
The patent forms the metal connection terminal part and touch panel wiring before forming the color filter layer. By performing this preliminary action, the metal structures are already in place and protected when the color filter is subsequently formed, preventing damage from alkaline developers during color filter processing.
Solution Approach 2:
The patent applies a protective layer or uses process control measures beforehand to cushion/protect the metal connection terminal from damage by alkaline developer. This prior protection ensures the metal structures survive the color filter formation process without degradation.
4Reliability
If metal wiring line is used, then low resistance is achieved, but design is restricted due to need to match light shielding layer of color filter
Solution Approach 1:
The patent uses a composite wiring structure where the metal film provides low resistance and the transparent conductive film provides optical performance. This composite approach decouples the electrical and optical requirements, allowing independent optimization and greater design flexibility compared to single-material wiring.
Solution Approach 2:
The wiring structure is segmented into multiple functional layers: metal film for electrical conduction and transparent conductive film for optical performance. This segmentation allows each layer to be optimized independently for its specific function, enhancing overall design flexibility and adaptability.
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 enables a touch panel with low resistance and low reflection characteristics, preventing damage to the wiring lines and ensuring high yield and performance, even when the color filter is formed after the touch panel layer, thus addressing the limitations of previous technologies.
Implementation Method 1
low reflection film... for the purpose of disposing an antireflection film on an aluminum alloy wiring line, in order to reduce reflection of incident light from outside a display apparatus
Implementation Method 2
high transmission to light from a light source for display
Data Source
AI summary
In a lead-out wiring area, a protective conductive film is formed on a bottom surface and a side surface of a first contact hole including a surface of a first low resistance conductive film, and a part of a surface of an upper interlayer insulating film, and a second protective conductive film is formed on a bottom surface and a side surface of a second contact hole including a surface of a second low resistance conductive film, and a part of the surface of the upper interlayer insulating film. Then, a lower layer terminal part for a lower layer wiring line is formed of a laminated structure of the first low resistance conductive film and the first protective conductive film, and an upper layer terminal part for an upper layer wiring line is formed of a laminated structure of the second low resistance conductive film and the second protective conductive film.