Photo-Aligned Liquid Crystal Display Substrate Cleaning
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving high display quality and large viewing angles with high contrast ratios, particularly due to defects and foreign materials affecting the alignment of liquid crystal molecules during the fabrication process.
Innovation Solution
A method of forming alignment layers using a photo-alignment technique, which involves forming an alignment solution on a substrate, curing it, exposing it to light to align the molecules, and then cleaning and baking the substrate to create anisotropic properties, thereby improving the alignment and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rubbing method or photo-alignment method is used to align liquid crystal molecules without applying an electric field, then the viewing angle is large and contrast ratio is great, but defects occur and uniform alignment is not achieved
Solution Approach 1:
The patent applies preliminary cleaning actions (wet cleaning with de-ionized water, bubble jet, air knife, or dry cleaning with ultrasonic waves) to the base substrate before forming the alignment layer. This preliminary cleaning removes foreign materials that would otherwise cause defects and disrupt uniform alignment, thereby improving alignment uniformity while reducing defects.
Solution Approach 2:
The patent replaces the traditional rubbing mechanical method with a photo-alignment method using light exposure. The alignment solution is coated on the substrate, then exposed to light to induce photopolymerization and molecular orientation without mechanical contact, eliminating defects caused by rubbing while achieving uniform alignment.
2Productivity
If cleaning is performed after exposing the alignment solution, then foreign materials are removed and defect ratio decreases, but additional process steps are required
Solution Approach 1:
The cleaning process is performed as a preliminary action after exposing the alignment solution but before final assembly. This timing removes foreign materials at the optimal point in the process, preventing defect formation while integrating smoothly into the existing fabrication sequence, thus improving yield without significantly increasing overall process 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
This approach results in a liquid crystal display device with enhanced display quality, reduced defect ratios, and increased contrast ratios by effectively aligning liquid crystal molecules, leading to improved performance and yield.
Implementation Method 1
At least one of the first alignment layer and the second alignment layer is formed by forming an alignment solution on a corresponding base substrate and curing the alignment solution to form an alignment layer
Implementation Method 2
the first cleaning may be a dry cleaning. In this case, the first cleaning may be conducted using ultrasonic waves
Data Source
AI summary
A liquid crystal display device is fabricated by forming a first alignment layer on a first base substrate. A second alignment layer is formed on a second base substrate. A liquid crystal is disposed on one of the first alignment layer and the second alignment layer. The first base substrate and the second base substrate are combined. At least one of the first alignment layer and the second alignment layer is formed by forming an alignment solution on a corresponding base substrate. An alignment layer is formed by curing the alignment solution. The alignment layer is aligned by radiating a light onto the base substrate, first cleaning the base substrate, and baking the alignment layer.