Touch Panel Darkening Layer for Low-Reflection Sensor Electrodes
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Solution Overview
Problem
Touch screens in electronic devices suffer from visibility issues due to external light reflectivity, which affects user experience and device thickness, and attempts to reduce reflection can compromise pixel aperture ratio.
Innovation Solution
A touch panel design incorporating a darkening layer with a multi-layer structure over conductive patterns to reduce external light reflectivity, comprising a conductive layer, a lower layer with an extinction coefficient of 2.5 or less, a middle layer with a refractive index of 2.3 or less, and an upper layer with the same extinction coefficient, achieving reflectivity of 4% or less, while maintaining conductivity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a darkening layer is added to reduce external light reflectivity, then touch sensor visibility is decreased, but device thickness increases
Solution Approach 1:
The patent applies composite materials by creating a multi-layer darkening structure comprising a lower layer (first conductive material), middle layer (second conductive material), and upper layer (third conductive material). Each layer has specific optical properties (extinction coefficient ≤2.5, refractive index ≤2.3) that work together to achieve reflectivity ≤4% while maintaining overall thinness and flexibility of the device.
Solution Approach 2:
The darkening layer is applied locally only to the conductive patterns (touch sensors and peripheral electrodes) rather than the entire display surface. This selective application reduces reflectivity where needed while preserving the aperture ratio and light transmission in the pixel regions, thereby avoiding unnecessary thickness increase.
2Object-affected harmful factors
If structure is added to limit reflectivity, then external light reflection is reduced, but pixel aperture ratio is inhibited
Solution Approach 1:
The darkening layer is selectively applied only to conductive patterns (touch sensors and peripheral electrodes) and not to the pixel regions. This local application ensures that reflectivity is reduced where conductive elements are present while the pixel aperture ratio remains unaffected, as light can still pass through the pixel areas without obstruction.
Solution Approach 2:
The darkening function is segmented and applied only to specific conductive pattern regions rather than uniformly across the entire display. The multi-layer structure is configured to provide darkening effect locally on electrodes while leaving the pixel areas transparent, thus resolving the conflict between reflection reduction and aperture ratio maintenance.
3Reliability
If conductive patterns are made more reflective, then electrical conductivity is improved, but touch sensor visibility increases
Solution Approach 1:
The patent uses composite materials by stacking multiple conductive layers with different optical properties. The lower layer provides primary conductivity, while the middle and upper layers with specific extinction coefficients (≤2.5) and refractive indices (≤2.3) reduce reflectivity. This composite structure maintains electrical conductivity while achieving reflectivity ≤4%, preventing touch sensor visibility.
Solution Approach 2:
The patent changes optical parameters of the conductive patterns by applying a multi-layer darkening structure. The extinction coefficient (≤2.5) and refractive index (≤2.3) of the darkening materials are optimized to reduce reflectivity while preserving electrical conductivity. This parameter optimization allows conductive patterns to maintain functionality while becoming visually less prominent.
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 reduces the visibility of touch sensors, decreases device thickness, and increases the aperture ratio of pixels, enhancing user experience and device performance.
Implementation Method 1
a darkening layer disposed over the conductive layer... each of the first and second conductive patterns may have an external light reflectivity lower than that of the conductive layer
Implementation Method 2
a lower layer disposed directly on the conductive layer and including a first conductive material having an extinction coefficient of about 2.5 or less
Implementation Method 3
a middle layer disposed between the upper layer and the lower layer and in contact with each of the upper and lower layers and including a third conductive material having a refractive index of about 2.3 or less
Data Source
AI summary
A touch panel is manufactured by a method that decreases undesirable reflections of external light while improving the visibility of emitted light. The touch panel includes a base layer including an active region responsive to an external touch to generate an electronic signal and a peripheral region adjacent to the active region, and a first conductive pattern disposed on the active region and a second conductive pattern disposed on the peripheral region, each of the first conductive pattern and the second conductive pattern including a conductive layer having an external light reflectivity and a darkening layer disposed over the conductive layer. External light reflectivity of each of the first and second conductive patterns is lower than that of the conductive layer.