Multiple Alignment Films for LCD Viewing Angle Correction
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Solution Overview
Problem
Current liquid crystal display (LCD) technologies face challenges such as gray-scale inversion in twisted nematic (TN) mode and color wash-out at large viewing angles in vertical alignment (VA) mode, primarily due to the limitations of the rubbing alignment method which requires complex and costly manufacturing processes.
Innovation Solution
The solution involves forming multiple alignment films on glass substrates using different materials and trench patterns to control pre-tilt angles of liquid crystal molecules, eliminating the need for additional development and etching processes, and allowing for different alignment film materials to be coated on specific areas of the substrates without increasing manufacturing complexity or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubbing alignment method is used to align liquid crystal molecules, then the alignment effect is achieved, but gray-scale inversion occurs at particular viewing angles and the manufacturing process becomes complex and costly
Solution Approach 1:
The patent divides the alignment film into multiple segments with different materials (first alignment film and second alignment film) having different rubbing directions. This segmentation allows different regions to provide different alignment effects, solving the gray-scale inversion problem while maintaining a relatively simple manufacturing process by using sequential coating methods
Solution Approach 2:
The patent applies different alignment film materials with different properties to different local regions (first and second alignment films with different rubbing directions). This local quality approach ensures optimal alignment performance in each region while avoiding the complexity of traditional methods
2Ease of manufacture
If the rubbing alignment method is used to provide single-direction alignment, then the alignment process is simple, but gray-scale inversion occurs at particular viewing angles
Solution Approach 1:
The alignment film is segmented into multiple materials (first and second alignment films) with different rubbing directions. This segmentation improves viewing angle performance by providing multi-directional alignment while maintaining ease of manufacture through sequential coating processes
Solution Approach 2:
The patent uses composite alignment film structures combining different alignment materials with different rubbing directions. This composite approach enhances viewing angle performance while keeping the manufacturing process simple through sequential application of different materials
3Manufacturing precision
If additional photo-resist coatings, exposures, development and etching are used to pattern alignment films, then the alignment direction can be controlled, but the manufacturing complexity and processing time increase
Solution Approach 1:
The patent performs preliminary action by sequentially coating different alignment film materials in specific patterns before the main assembly process. This preliminary patterning achieves precise alignment direction control without requiring subsequent photo-resist, exposure, development, and etching steps, thereby reducing manufacturing complexity
Solution Approach 2:
The patent extracts and eliminates the complex photo-resist coating, exposure, development, and etching processes from the manufacturing flow. Instead, it uses direct sequential coating of different alignment materials to achieve the same patterning effect, significantly reducing manufacturing complexity and processing time
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 improves display performance by reducing gray-scale inversion and color wash-out, enhancing the viewing angle range and response time of LCDs without requiring additional photo-resist coatings or complex processing steps.
Implementation Method 1
the alignment orientations of the liquid crystal molecules are altered by applying voltages externally... alignment films coated on the conductive glass substrates with very fine trenches formed therein by rubbing. The fluidity of the liquid crystal molecules tends to align the molecules along the trench direction.
Implementation Method 2
the liquid crystal molecules will be aligned at a twisted angle of 90°. When there is no voltage applied, the light entering the liquid crystal element propagates with the polarization that changes according to the twisted direction of the liquid crystal molecules.
Implementation Method 3
when a voltage is applied, the liquid crystal molecules are aligned towards a direction in which the electric field is applied and are consequently aligned perpendicularly to the alignment films.
Implementation Method 4
protrusions are used to cause the liquid crystal molecules to present a pre-tilt angle in a stationary alignment status, so that when applied with a voltage, the liquid crystal molecules will tilt towards various orientations rapidly.
Data Source
AI summary
A method for forming the alignment films on the substrate and a pixel structure of a liquid crystal display are disclosed. The pixel structure comprises a plurality of pixel units arranged in arrays. Each of the pixel units comprises a first substrate, a second substrate, two first alignment films and two second alignment films. The first alignment film is different from the second alignment film. The second substrate is disposed opposite to the first substrate. The two first alignment films and the two second alignment films are individually disposed on the first substrate and the second substrate, while each of the first alignment films is disposed substantially opposite to one of the second alignment films. The method for forming the alignment films comprises the following steps: (1) forming a trench on the substrate to divide each of the pixel units into a first sub-pixel area and a second sub-pixel area, (2) forming the first alignment film on the first sub-pixel area of the substrate and then, (3) forming a second alignment film on the second sub-pixel area of the substrate at last.