Extending Pixel Electrodes into Light-Shield Area to Stop Liquid Crystal Light Leakage
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Solution Overview
Problem
In liquid crystal display devices with transmissive display functions, defects in liquid crystal molecule alignment at the end portions of the active area lead to light leakage due to interactions between oblique and vertical electric fields, which existing technologies have difficulty in preventing.
Innovation Solution
The liquid crystal display device design includes pixel electrodes and color filters that extend into the light-shield area beyond the boundary between the active and light-shield areas, and optionally incorporates a dummy pixel electrode in the light-shield area to minimize the impact of oblique electric fields, thereby reducing defects in liquid crystal alignment and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the counter-electrode covers the color filters in the light-shield area to prevent misalignment, then substrate attachment alignment is improved, but oblique electric fields are generated that cause liquid crystal molecule misalignment at end portions of the active area
Solution Approach 1:
The patent divides the counter-electrode into two distinct regions: a first region that covers the color filters in the light-shield area to ensure substrate alignment, and a second region that extends into the light-shield area beyond the color filter region to eliminate oblique electric fields. This segmentation allows each region to perform its specific function independently, resolving the contradiction between alignment precision and molecule alignment reliability.
Solution Approach 2:
The second region of the counter-electrode acts as an intermediary element that extends into the light-shield area to neutralize oblique electric fields. This intermediary structure prevents the harmful electric field interactions from affecting the liquid crystal molecules at the end portions of the active area, while the first region maintains the substrate alignment function.
2Manufacturing precision
If color filters are disposed spaced apart to prevent non-uniformity in liquid crystal layer gap, then gap uniformity is improved, but light-shield area requires additional color filters that extend electric fields into active area
Solution Approach 1:
The counter-electrode is segmented into a first region covering the spaced-apart color filters and a second region extending beyond them. This segmentation allows the color filters to be spaced apart for gap uniformity while the second region of the counter-electrode prevents oblique electric fields from extending into the active area, thus resolving the contradiction.
Solution Approach 2:
The patent converts the potentially harmful extension of electric fields into a beneficial structure by designing the second region of the counter-electrode to extend into the light-shield area. This extension, which might seem to increase field interference, actually serves to neutralize oblique electric fields and protect the active area, transforming the potential harm into a benefit.
Data Source
AI summary
A liquid crystal display device includes an active area which is composed of pixels arrayed in a matrix, and a light-shield area surrounding the active area. The liquid crystal display device includes a first substrate including pixel electrodes disposed in the respective pixels, a second substrate including color filters disposed in the respective pixels, and a counter-electrode which is disposed to cover the color filters and extends from the active area to at least a part of the light-shield area, and a liquid crystal layer held between the first substrate and the second substrate. The pixel electrode and the color filter of the pixel, which is disposed at an end portion of the active area, extend into the light-shield area beyond a boundary between the active area and the light-shield area.