OCB LCD Homeotropic Alignment Film Printing Process
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Solution Overview
Problem
The manufacturing methods for OCB-mode LCDs are complex and costly due to the need for expensive masks and excessive exposure, leading to high production costs and image defects like rubbing mura and residual pieces.
Innovation Solution
A method is developed where a homeotropic alignment film is formed over the opaque area of the substrate using printing techniques, eliminating the need for additional masks and gradation exposure, and allowing for high-pretilt angle alignment of liquid crystal molecules to shorten transition times without affecting the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gradation exposure with mask is used to form saw-toothed surface, then liquid crystal response speed is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent extracts the mask and gradation exposure steps from the manufacturing process by directly forming the homeotropic alignment film over the opaque area using printing techniques. This removes the complex photolithography equipment and multiple exposure steps while achieving the same functional result of creating high pretilt angle regions for faster liquid crystal response.
Solution Approach 2:
The patent replaces expensive, complex photolithography masks with simple printing processes that use inexpensive materials and methods. The printing approach uses straightforward deposition techniques without requiring costly mask fabrication, maintenance, and alignment equipment, significantly reducing manufacturing complexity and cost.
2Manufacturing precision
If multiple alignment films are formed by photolithography, then alignment precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by forming the homeotropic alignment film specifically over the opaque area where high pretilt angles are needed, rather than uniformly across the entire substrate. This localized approach achieves precise alignment control exactly where required for liquid crystal transition, while avoiding unnecessary processing in other areas, thus maintaining precision without increasing overall manufacturing cost.
Solution Approach 2:
The patent replaces expensive photolithography processes with inexpensive printing techniques for forming alignment films. The printing method uses simple material deposition without requiring costly photolithography equipment, masks, and chemicals, achieving the necessary alignment precision at a fraction of the manufacturing cost.
3Manufacturing precision
If repeated rubbing is performed to improve homogeneous alignment, then alignment quality is improved, but image defects and yield loss increase
Solution Approach 1:
The patent extracts the repeated rubbing steps from the manufacturing process by directly forming the homeotropic alignment film through printing. This eliminates the mechanical rubbing process that causes rubbing mura and residual pieces, achieving high alignment quality without the harmful side effects that reduce yield and image quality.
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 simplifies the manufacturing process, reduces costs, and prevents image defects, while maintaining high image quality by aligning liquid crystal molecules with high pretilt angles over the opaque area, thus shortening transition times between splay and bend states.
Implementation Method 1
forming a homeotropic alignment film over the opaque area, i.e. the area corresponding to the black matrix of a liquid crystal display device, of a substrate utilizing printing, whereby the liquid crystal molecules over the opaque area are aligned with high pretilt angles
Data Source
AI summary
A method for manufacturing a substrate of a flat panel display device is disclosed. The method includes following steps: providing a substrate having patterned transparent electrode thereon; and forming an alignment layer on the surface of the transparent electrode. The formed alignment layer includes a homeotropic alignment film and a homogeneous alignment film adjacent to the homeotropic alignment film. Moreover, the homeotropic alignment film is formed utilizing printing on or on a periphery of to the homogeneous alignment film. Through this method, the flat panel display device can be manufactured without increasing the quantity of the mask cycles, and without a complex process of gradation exposure. Moreover, the problem resulted from multiple rubbing can be reduced, and the cost for manufacturing can be decreased.