Transparent Conductive Laminate for Low-Color Touch Panels
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Solution Overview
Problem
Transparent touch panels face issues with color tone changes due to optical interference from transparent electroconductive layers, leading to 'skeleton visibility' problems and reduced transparency from lubricating layers with fine particles, which affect both display quality and electrical connectivity.
Innovation Solution
A transparent electroconductive laminate is developed by stacking a hardcoat layer, an optical interference layer, and a transparent electroconductive layer on a transparent organic polymer substrate, with specific refractive index and thickness conditions to minimize color tone changes and haze, while using ultrafine particles to enhance lubricity without scattering light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent electroconductive layer is directly stacked on the transparent organic polymer substrate, then electrical conductivity is achieved, but coloration of transmitted light occurs due to optical interference and light absorption
Solution Approach 1:
An optical interference layer is introduced as an intermediary between the transparent electroconductive layer and the transparent organic polymer substrate. This intermediate layer suppresses optical interference and light absorption effects, thereby reducing coloration of transmitted light while maintaining the electrical conductivity function of the electroconductive layer.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with different functional properties: the transparent organic polymer substrate provides mechanical support, the optical interference layer controls optical properties, and the transparent electroconductive layer provides electrical conductivity. This composite approach allows simultaneous optimization of electrical and optical characteristics.
2Strength
If a hardcoat layer is coated on the transparent organic polymer substrate to protect the surface and flatten it, then surface protection and flattening are achieved, but reflection at the interface causes coloring interference
Solution Approach 1:
The refractive index of the hardcoat layer is specifically controlled to match that of the transparent organic polymer substrate. By changing this optical parameter, reflection at the interface is minimized, thereby suppressing coloring interference while maintaining surface protection and flattening functions.
Solution Approach 2:
The optical interference layer serves as an intermediary between the hardcoat layer and the transparent electroconductive layer, suppressing reflection and optical interference at these interfaces, thereby reducing coloring interference while preserving the protective function of the hardcoat layer.
3Ease of operation
If a lubricating layer with fine particles is used to enhance lubricity, then lubricity is improved, but transparency is reduced due to light scattering
Solution Approach 1:
The particle size of the ultrafine particles in the lubricating layer is precisely controlled to be 100 nm or less. By changing this size parameter, the particles become small enough to minimize light scattering while still providing adequate lubricity, thus resolving the contradiction between lubricity and transparency.
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 provides a transparent electroconductive laminate suitable for display devices, reducing 'skeleton visibility' and maintaining high transparency and lubricity, thus improving display quality and electrical connectivity.
Implementation Method 1
coloration of light passing through the transparent electroconductive laminate occurs, for example, due to optical interference resulting from reflection at the interface between the substrate and the transparent electroconductive layer
Implementation Method 2
reflection at the interface between the substrate and the transparent electroconductive layer
Implementation Method 3
use of ultrafine particles to enhance lubricity without scattering light
Data Source
AI summary
The present invention provides a transparent electroconductive laminate suitable for use in combination with a display device such as a liquid crystal display, and a transparent touch panel having the transparent electroconductive laminate. The transparent electroconductive laminate comprises a transparent organic polymer substrate 33 having, on at least one surface thereof, a hardcoat (HC) layer 33h, an optical interference layer 32, and a transparent electroconductive layer 31 in this order. The transparent electroconductive laminate satisfies the following conditions: the refractive indexes n3 and n3h of the transparent organic polymer substrate and the HC layer satisfy the following formula: |n3−n3h|≤0.02, the thickness of the HC layer is from 1 to 10 μm, the thickness of the optical interference layer is from 5 to 500 nm, the thickness of the transparent electroconductive layer is from 5 to 200 nm, the total light transmittance is 85% or more, and the b* value is from −1.0 to less than 1.5 and the transparent touch panel has the transparent electroconductive laminate.