IPS-LCD Electrode Structure for Uniform Light Irradiation
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Solution Overview
Problem
In-plane switching liquid crystal display (IPS-LCD) devices suffer from chuck stains and step stains due to non-uniform light irradiation during electrode formation, leading to brightness differences and image imperfections, and the use of transparent conductive materials results in high resistivity and signal delays, especially in large-sized displays.
Innovation Solution
The solution involves forming pixel and common electrodes with opaque metal layers and a subsequent metal oxide layer using ultraviolet (UV) rays, which reduces reflectance and resistivity, preventing chuck stains and improving display quality by ensuring uniform critical dimensions and reducing step differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent conductive materials are used for pixel and common electrodes, then light transmission is improved, but resistivity increases and signal delays occur
Solution Approach 1:
The patent uses a composite electrode structure consisting of a transparent conductive layer (such as ITO) combined with an opaque metal layer (such as aluminum or its alloy). This composite structure combines the advantages of both materials: the transparent conductive layer provides light transmission capability while the opaque metal layer provides low resistivity and fast signal transmission. The layers are formed in a stacked configuration where the opaque metal layer is deposited on the transparent conductive layer, creating an electrode that satisfies both optical and electrical performance requirements.
2Ease of manufacture
If non-uniform light irradiation is used during electrode formation, then manufacturing process is simplified, but chuck stains and step stains occur
Solution Approach 1:
The patent applies different properties to different parts of the electrode structure to address the staining problem. Specifically, the electrode is designed with a stacked structure where the opaque metal layer is positioned on the transparent conductive layer. This local differentiation in material properties (opacity vs. transparency) allows the opaque layer to block irregular light reflection that causes chuck stains, while the transparent layer maintains light transmission for display functionality. The local quality change effectively prevents stain formation without complicating the manufacturing process.
3Reliability
If opaque metal layers are used for electrodes, then resistivity and reflectance are reduced, but light transmission is blocked
Solution Approach 1:
The patent employs a composite electrode structure where a transparent conductive layer (providing light transmission) is combined with an opaque metal layer (providing low resistivity). The transparent conductive layer allows light to pass through for display visibility, while the opaque metal layer deposited on top provides excellent electrical conductivity and low resistivity. This composite approach resolves the contradiction by allowing each layer to fulfill its primary function without compromising the other.
4Manufacturing precision
If step differences in electrode structure are reduced, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a stacked composite structure of transparent conductive layer and opaque metal layer that inherently reduces step differences. The sequential deposition process allows for precise thickness control of each layer, and the combination of materials with complementary properties creates a more uniform electrode surface. While the material composition becomes more complex, the manufacturing process remains relatively straightforward using standard sputtering or evaporation techniques, achieving good step difference control without excessive complexity increase.
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
This approach prevents chuck stains and step stains, enhances display quality by reducing resistivity and signal delays, and improves contrast ratios by using opaque metal layers with low reflectance and low resistivity, thus addressing the limitations of existing IPS-LCD technologies.
Implementation Method 1
irradiating ultraviolet (UV) rays onto the opaque metal layer to form a metal oxide layer on the opaque metal layer
Data Source
AI summary
A fabricating method of an array substrate for an in-plane switching liquid crystal display device includes: forming a gate line and a common line on a substrate, the common line spaced apart from the gate line; forming a data line crossing the gate line to define a pixel region; forming a thin film transistor connected to the gate line and the data line; forming a pixel electrode and a common electrode in the pixel region, each of the pixel electrode and the common electrode including an opaque metal layer; and irradiating ultraviolet rays onto the opaque metal layer to form a metal oxide layer on the opaque metal layer.