Vertical Alignment LCD Electrode Structure for Static Control
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Solution Overview
Problem
Liquid crystal display (LCD) manufacturing processes face challenges with narrow viewing angles, static electricity generation, and defects due to the absence of electrodes on the cover substrate in in-plane switching (IPS) and plane-to-line switching (PLS) modes, which limits the use of electrostatic chucking and increases manufacturing defects.
Innovation Solution
The development of a high transmittance-vertical alignment (HT-VA) LCD with a unique electrode structure on both substrates, including projection and stem portions on pixel electrodes, and a patterned conductive layer on the upper substrate to reduce static electricity and enhance manufacturing processes, while maintaining high transmittance and contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrodes are disposed only on the lower substrate (as in IPS and PLS modes), then the manufacturing process is simplified, but static electricity is easily generated and electrostatic chucking cannot be used
Solution Approach 1:
The patent inverts the conventional electrode arrangement by disposing electrodes on both the lower substrate (first substrate) and the upper substrate (second substrate). Specifically, the first electrode is formed on the lower substrate while the second electrode is formed on the upper substrate, reversing the traditional single-substrate electrode configuration. This inversion allows electrostatic chucking to be applied to the upper substrate during manufacturing, eliminating static electricity accumulation while maintaining manufacturing simplicity.
2Object-affected harmful factors
If an electrode layer is disposed on the rear portion of the cover substrate to prevent static electricity, then static electricity is reduced, but defects are generated due to scratches and chemical exposure
Solution Approach 1:
The patent applies preliminary action by forming the second electrode on the upper substrate before the final assembly and sealing processes. The electrode pattern is pre-formed on the upper substrate using protective measures during manufacturing, allowing electrostatic chucking to be implemented early in the process. This prevents static electricity accumulation before defects can occur, while the electrode structure itself is protected from scratches and chemical exposure through proper sealing and protective layers.
3Stability of the object's composition
If vertical alignment mode is used, then the liquid crystal molecules are initially aligned vertically, but the viewing angle becomes narrow when voltage is applied
Solution Approach 1:
The patent applies local quality by creating different electrode patterns in different regions of the display. The first electrode on the lower substrate and the second electrode on the upper substrate are configured with specific patterns (such as interdigitated or complementary patterns) that generate localized electric field distributions. This local variation in electrode configuration allows the liquid crystal molecules to maintain vertical alignment stability while achieving wider viewing angles through controlled local orientation changes when voltage is applied.
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 HT-VA LCD achieves improved transmittance, reduced static electricity, and enhanced manufacturing efficiency by allowing electrostatic chucking, resulting in better display characteristics and reduced defects during manufacturing.
Implementation Method 1
an electrostatic chuck (ESC) cannot be used in manufacturing the IPS or PLS mode LCDs, since the cover substrate does not include an electrode, which would normally be used to generate electrostatic forces with the ESC during the manufacturing process
Implementation Method 2
the transmittance changes according to an alignment of liquid crystal molecules in the liquid crystal layer, which are aligned by an electric field that is generated by applying a voltage to electrodes on the TFT substrate and/or the cover substrate
Data Source
AI summary
A vertical alignment liquid crystal display includes a first substrate and a second substrate disposed opposite the first substrate. The first substrate includes a first insulation substrate, as well as a first pixel electrode and a second pixel electrode disposed in a same layer with the first pixel electrode on the first insulation substrate. The second substrate includes a second insulation substrate, a first patterned conductive layer disposed on only a portion of the second insulation substrate which is above the first pixel electrode, and a second patterned conductive layer disposed on only a portion of the second insulation substrate which is above the second pixel electrode.