LCD Border Area Ion Migration Control
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Solution Overview
Problem
Liquid crystal displays (LCDs) suffer from non-uniformity issues such as image retention, sticking, flares, and permanent black areas due to ion migration, leading to diminished optical performance and increased maintenance costs.
Innovation Solution
A liquid crystal display with a border area driven by display-protection images that inhibit ion migration, featuring a checkerboard pattern and different liquid crystal alignment directions to promote ion migration away from the display area, and an ion reservoir to retain migrating ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LCD operation is used, then display function is maintained, but ion migration causes defects and reduces display lifetime
Solution Approach 1:
The patent extracts ions from the display area by creating a dedicated border area that serves as an ion trap. The border area pixels are driven to create electric fields that actively migrate ions away from the display area and concentrate them in the border region, effectively removing the harmful ion accumulation problem from the functional display area.
Solution Approach 2:
The border area pixels serve as an intermediary mechanism between the display area and the ion migration problem. By driving these intermediary pixels with specific patterns (such as checkerboard patterns), the system creates controlled electric fields that mediate ion movement, directing ions into the border area where they can be contained without affecting display quality.
2Reliability
If border area is added to control ion migration, then ion accumulation is reduced, but device complexity increases
Solution Approach 1:
The border area pixels perform multiple functions: they maintain the physical structure of the pixel array, provide additional display real estate, and serve as active ion migration control elements. By driving these pixels with display-protection images, the same structural elements contribute to both display functionality and ion management, reducing the need for separate ion control mechanisms.
Solution Approach 2:
The pixel array itself serves the dual purpose of displaying images and controlling ion migration. The border area pixels, when driven with appropriate patterns, automatically perform ion trapping functions without requiring external ion control structures. The display structure serves its own ion management needs through intelligent driving patterns.
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 solution effectively reduces ion accumulation in corners, preventing defects and extending the lifetime of LCDs by controlling ion migration and direction, thereby enhancing the display's robustness and reducing maintenance needs.
Implementation Method 1
The polarization of the light is altered by liquid crystal layer, depending on the electric field applied across liquid crystal layer between respective pixel mirrors and the common electrode
Implementation Method 2
ion migration to corners of the pixel array can cause various display defects
Data Source
AI summary
A liquid crystal display includes a display area and a border area at least partially surrounding the display area, where the display area displays images for viewing and the border area displays display-protection images, which are used to control ion migration in the liquid crystal layer. In a more particular embodiment, the border area displays a series of checkerboard pattern(s), where the checkerboard patterns can alternate between initial and inverted values. The display-protection images protect the liquid crystal display from migrating ions accumulating in particular regions of the pixel array and causing permanent defects in the display area. A liquid crystal display that includes a liquid crystal alignment layer having a plurality of liquid crystal alignment directions is also disclosed. The customized liquid crystal alignment director(s) over the border area promote ion migration away from the display area.