Anti-static Layer for Touch Sensing LCDs
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Solution Overview
Problem
Touch sensing in IPS mode and FFS mode LCD devices is hindered by anti-static layers made of transparent conductive materials like ITO and IZO, which prevent the detection of capacitance changes due to static electricity discharge, rendering them non-functional for touch operations.
Innovation Solution
A touch sensing type LCD device with an anti-static layer comprising a conductive polymer, a UV-setting binder, and transparent silica, offering a sheet resistance of several tens of Mega ohms per square to several Giga ohms per square, allowing for effective static electricity discharge while enabling touch sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-static layer made of transparent conductive material (ITO/IZO) is used, then static electricity discharge is prevented, but touch sensing capability is lost
Solution Approach 1:
The patent changes the electrical resistance parameter of the anti-static layer by using conductive polymer with controlled doping levels. The resistance is adjusted to a specific range (10^-3 to 10^2 ohm·cm) that allows both static discharge and capacitance change detection, resolving the contradiction between protection and sensing functionality.
Solution Approach 2:
The patent employs composite materials by combining conductive polymer with transparent resin and inorganic particles. This composite structure provides both the electrical conductivity needed for static protection and the optical transparency required for touch sensing, eliminating the functional conflict of traditional ITO/IZO layers.
2Ease of manufacture
If conventional anti-static layer materials (ITO/IZO) are used, then manufacturing is simple, but the layer is scratched easily during cleaning
Solution Approach 1:
The patent uses composite materials comprising conductive polymer, transparent resin, and inorganic particles (such as silica). This composite structure provides both ease of manufacture through solution processing and enhanced scratch resistance due to the inorganic particle reinforcement, achieving both manufacturing simplicity and mechanical durability.
Solution Approach 2:
The patent creates a flexible thin film structure that can be easily deposited on substrates while maintaining scratch resistance. The thin film approach simplifies manufacturing compared to rigid materials, while the polymer-based composition provides inherent flexibility and resistance to scratching during cleaning operations.
3Illumination intensity
If ITO/IZO anti-static layers are used, then transparency is achieved, but capacitance change detection for touch sensing is blocked
Solution Approach 1:
The patent optimizes the electrical resistance parameter of the anti-static layer to a specific range (10^-3 to 10^2 ohm·cm). This parameter optimization allows the layer to maintain optical transparency while enabling capacitance change detection for touch sensing, resolving the contradiction between transparency and sensing capability.
Solution Approach 2:
The conductive polymer acts as an intermediary material that mediates between the transparent substrate and the touch sensing electrode. It provides sufficient electrical conductivity for capacitance detection while maintaining optical transparency, serving as a functional bridge that enables both transparency and sensing.
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 proposed solution allows for the detection of capacitance changes upon touch, enabling the operation of LCD devices with improved resistance to static electricity without damaging the device, and provides a durable anti-static layer with hardness greater than 6H, preventing scratches during manufacturing and cleaning processes.
Implementation Method 1
an anti-static layer on an outer side of the second substrate and including a conductive polymer
Implementation Method 2
irradiating a UV light onto the anti-static layer such that the anti-static layer has a hardness being equal to or greater than 6H
Data Source
AI summary
A touch sensing type liquid crystal display device includes an array substrate including a first substrate, a common electrode, a pixel electrode, and a touch sensing unit; a color filter substrate including a second substrate and facing the array substrate; an anti-static layer on an outer side of the second substrate and including a conductive polymer, a UV-setting binder and transparent silica and having a sheet resistance of several tens of Mega ohms per square (Ω/sq) to several Giga ohms per square (Ω/sq); and a liquid crystal layer between the first substrate and an inner side of the second substrate.