Metal Nanowire Transparent Conductor for Display Touch Sensors
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Solution Overview
Problem
Integrating a touch sensor with a display is challenging due to electrical noise interference and the need for optically transparent conductors that do not degrade the optical performance of the display.
Innovation Solution
An optically transparent conductive layer made of metal nanowires, such as silver nanowires, is integrated into the display stack, either between the polarizer and the backlight or above the polarizer, with the nanowires oriented to enhance transparency and reduce sheet resistance, and optionally combined with a polarizing filter to minimize reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical conductors are used to form part of the touch sensor, then electrical conductivity is improved, but optical performance of the display deteriorates due to lack of transparency
Solution Approach 1:
The patent changes the physical parameters of the conductor by using nanowire-scale dimensions (diameter of 1-100 nm) and specific aspect ratios (length-to-diameter ratio of 10:1 to 100:1). This parameter change allows the conductor to be thin enough to be transparent while maintaining electrical conductivity through the nanowire network structure.
Solution Approach 2:
The patent employs composite materials by combining metal nanowires (such as silver, aluminum, or copper nanowires) with transparent materials to form a transparent conductive layer. This composite structure provides both the electrical conductivity of metal and the optical transparency of the transparent matrix material.
2Adaptability or versatility
If electrical conductors are integrated into the display stack, then touch sensor functionality is improved, but electrical noise interference increases
Solution Approach 1:
The patent uses the transparent conductive layer as an intermediary element positioned between the touch sensor electrodes and the display components that generate electrical noise. This intermediary layer acts as a shield that blocks electromagnetic interference from reaching the sensitive touch sensor circuits while allowing the touch sensor to function normally.
3Illumination intensity
If metal nanowires are oriented along a specific direction to enhance transparency, then optical performance is improved, but sheet resistance increases due to anisotropic distribution
Solution Approach 1:
The patent applies local quality by creating regions with different nanowire orientations. The nanowire network includes both oriented nanowires (for optical transparency) and randomly oriented nanowires (for electrical conductivity). This local variation in nanowire arrangement allows different regions to optimize for their specific function while contributing to the overall performance of the transparent conductive layer.
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 metal nanowire conductive layer provides effective shielding from electrical noise while maintaining high optical transparency and conductivity, improving the performance of touch sensors and force sensors within the display stack.
Implementation Method 1
the transparent conductive layer shields the touch sensor from electrical noise generated by the force sensor
Implementation Method 2
A transparent conductive layer may be disposed between the polarizer layer and the organic light emitting display
Data Source
AI summary
An optically transparent conductive layer for a display stack. In some cases, the optically transparent conductive layer is a metal nanowire layer that is disposed on or near a polarizing layer within the display stack.