ZnO Rear Electrode for IPS LCD Static Protection
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Solution Overview
Problem
In-plane switching (IPS) mode liquid crystal display (LCD) devices face issues with static electricity damage to the color filter substrate due to the absence of conductive materials, leading to increased production costs and complexities in the rework process, particularly with the use of expensive indium-tin-oxide (ITO) and indium-zinc-oxide (IZO) for rear side electrodes.
Innovation Solution
A color filter substrate is fabricated using a first rear side electrode formed of zinc oxide (ZnO) with additional compounds having second or fourth valence, a lattice-shaped black matrix, a color filter layer in openings of the black matrix, and an overcoat layer, with a rework process involving a potassium hydroxide (KOH)-based stripping solution to completely remove these layers, reducing production costs and simplifying the rework process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO or IZO is used for the rear side electrode to prevent static electricity damage, then the reliability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent replaces expensive ITO/IZO materials with a cheaper alternative consisting of an organic insulating layer and a transparent conductive layer. This cheaper material combination achieves the same static electricity protection function without the high cost associated with indium-based materials, directly addressing the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The patent uses a composite structure comprising an organic insulating layer (such as polyimide) combined with a transparent conductive layer (such as ITO, IZO, or ZnO). This composite material approach provides effective static electricity protection while offering flexibility in material selection to balance performance and cost, resolving the contradiction between reliability and ease of manufacture.
2Reliability
If ITO or IZO is used for the rear side electrode, then the static electricity protection is improved, but the rework process complexity increases
Solution Approach 1:
The patent segments the protective layer into two distinct functional layers: an organic insulating layer and a transparent conductive layer. This segmentation allows the organic insulating layer to be selectively removed during rework processes without affecting the transparent conductive layer, which remains to provide continued static electricity protection. This resolves the contradiction by simplifying the rework process while maintaining reliability.
Solution Approach 2:
The organic insulating layer acts as an intermediary layer between the substrate and the transparent conductive layer. During rework processes, this intermediary layer can be selectively removed to access the transparent conductive layer for repair or modification, while the transparent conductive layer itself can serve as a protective intermediary during subsequent processing steps. This mediator approach simplifies rework complexity while maintaining static electricity protection.
3Reliability
If a transparent conductive layer is added to provide static electricity protection, then the reliability is improved, but the device structure complexity increases
Solution Approach 1:
The transparent conductive layer serves multiple functions simultaneously: it provides static electricity protection, maintains optical transparency for display performance, and can serve as an adhesive layer between the organic insulating layer and the color filter substrate. This multi-functionality reduces the need for additional separate layers, thereby improving reliability without proportionally increasing structural complexity.
Solution Approach 2:
The patent merges the static electricity protection function with the existing transparent conductive layer structure that would otherwise be required for optical performance. By combining these functions into a single layer (or integrated layer system), the patent achieves improved reliability through static electricity protection without adding separate dedicated protective layers, thus minimizing the increase in device structure complexity.
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 use of ZnO-based electrodes and organic insulating materials for the color filter substrate effectively prevents static electricity damage, reduces production costs by using less expensive materials, and simplifies the rework process, improving the overall efficiency and cost-effectiveness of IPS mode LCD device manufacturing.
Implementation Method 1
a first rear side electrode on a first surface of a substrate and formed of a first transparent conductive material including zinc oxide (ZnO) and at least two compounds having second or fourth valence
Implementation Method 2
a rework process involving a potassium hydroxide (KOH)-based stripping solution to completely remove these layers
Data Source
AI summary
A color filter substrate for an in-plane switching mode liquid crystal display device includes a first rear side electrode on a first surface of a substrate and formed of a first transparent conductive material including zinc oxide (ZnO) and at least two compounds having second or fourth valence, the first rear side electrode having a first thickness; a black matrix having a lattice shape and a plurality of openings in the lattice shape, the black matrix disposed on a second surface, which is opposite to the first surface, of the substrate; a color filter layer in the plurality of openings; and an overcoat layer on the black matrix and the color filter layer.