Transparent Conductor Shading Reduction via Transmittance Control
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Solution Overview
Problem
Transparent conductors with a laminate structure of metal oxide layers and a metal layer face issues with shading due to differences in transmittance between conductive and insulating parts, especially after being covered with a glass layer, which affects the image quality of touch panels.
Innovation Solution
A transparent conductor is designed with a laminate structure including a transmittance-controlling layer, a metal layer, and a metal oxide layer, where the transmittance difference between the conductive and insulating parts is controlled to be 4% or more before being covered with a glass layer, using a configuration that includes a transparent resin substrate, a transmittance-controlling layer, a metal layer containing silver or a silver alloy, and a metal oxide layer, to minimize shading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent conductor with a laminate structure of metal oxide layers and a metal layer is used, then low resistance is achieved, but shading occurs due to transmittance difference between conductive and insulating parts
Solution Approach 1:
The patent applies local quality by making the transmittance-controlling layer transparent in the insulating part (where it remains after etching) while allowing the conductive part (with metal layer) to have different optical properties. This localized transparency control eliminates shading in the insulating part while maintaining low resistance in the conductive part through the metal layer.
Solution Approach 2:
The transmittance-controlling layer acts as an intermediary element that mediates between the metal layer (providing conductivity) and the substrate. By controlling the transmittance of this intermediate layer, the patent balances the optical properties of conductive and insulating parts, preventing shading while allowing the metal layer to provide low resistance.
2Object-generated harmful factors
If the transmittance difference between conductive and insulating parts is reduced before covering with glass layer, then shading is minimized, but the transmittance difference increases after covering with glass layer
Solution Approach 1:
The patent applies preliminary action by pre-controlling the transmittance of the transmittance-controlling layer before the glass layer is applied. By optimizing the transmittance at this stage, the patent ensures that even though the glass layer changes the absolute transmittance values, the relative difference between conductive and insulating parts remains controlled, preventing shading.
3Reliability
If ITO film is thickened to lower resistance, then electrical conductivity improves, but transmittance decreases
Solution Approach 1:
The patent segments the transparent conductor into multiple functional layers: a thin metal oxide layer (providing transparency) and a separate metal layer (providing conductivity). This segmentation allows each layer to be optimized independently - the metal oxide layer remains thin for high transmittance while the metal layer provides low resistance, avoiding the trade-off present in thick ITO films.
Solution Approach 2:
The patent uses composite materials by combining metal oxide (transparent but resistive) with metal (conductive but opaque). This composite structure leverages the complementary properties of both materials - the metal oxide provides transparency while the metal provides conductivity, achieving both high transmittance and low resistance simultaneously.
Data Source
AI summary
The transparent conductor involves a first laminate part including a transparent resin substrate and a transmittance-controlling layer, and a second laminate part including the transparent resin substrate, the transmittance-controlling layer, a metal layer containing silver or a silver alloy, and a metal oxide layer in the order presented. The first laminate part and the second laminate part are adjacent to each other in a direction perpendicular to the direction of lamination of the first laminate part and the second laminate part, and the difference between the transmittance of the first laminate part in the direction of lamination, T1, and the transmittance of the second laminate part in the direction of lamination, T2, (T2−T1) is 4% or more.