Liquid Crystal Device Electrode Thickness Optimization
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Solution Overview
Problem
In fringe field switching (FFS) mode liquid crystal devices, the thickness of electrodes affects the rubbing process, leading to defects and increased electrical resistance, which results in decreased image quality and luminance non-uniformity due to the large steps and variations in electrode thickness.
Innovation Solution
A liquid crystal device configuration where the second electrode layer is formed with a smaller thickness than the first electrode layer, reducing the step height and preventing rubbing defects, while maintaining a balanced electrical resistance by adjusting the thickness and material resistivity of both layers, allowing for high-quality image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode is formed with large thickness, then the rubbing process can be performed, but rubbing defects occur inside the openings of the common electrode due to large steps
Solution Approach 1:
The patent applies local quality by forming the pixel electrode with a thickness that is locally optimized for each region: in the pixel region, the pixel electrode thickness is designed to be greater than the common electrode thickness to prevent rubbing defects, while in the non-pixel region, the thickness relationship can be different. This localized thickness optimization resolves the contradiction between enabling the rubbing process and preventing rubbing defects in the openings.
2Manufacturing precision
If the thickness of the common electrode and pixel electrode are reduced, then rubbing defects are suppressed, but the electrical resistance of the common electrode is increased
Solution Approach 1:
The patent uses local quality by differentiating the thickness requirements in different regions: the pixel electrode in the pixel region is made thicker than the common electrode to maintain low electrical resistance where current flows, while the common electrode thickness is optimized for rubbing process compatibility. This regional differentiation allows both rubbing defect suppression and electrical resistance uniformity to be achieved.
3Device complexity
If the pixel electrode is formed at the same thickness as the common electrode, then the structure is simplified, but rubbing defects occur due to large steps
Solution Approach 1:
The patent resolves the contradiction by applying local quality: instead of using uniform thickness throughout, the pixel electrode thickness is locally increased in the pixel region to be greater than the common electrode thickness. This localized thickness variation prevents rubbing defects while maintaining relatively simple manufacturing processes, as the thickness differentiation is achieved through standard thin-film deposition techniques with regional control.
Data Source
AI summary
A liquid crystal device, which has a plurality of pixels and switching elements provided in correspondence with the pixels, includes an element substrate, an interlayer insulating film, a first electrode layer, and a second electrode layer. The switching elements are formed in the element substrate. The interlayer insulating film is formed on the switching elements. The first electrode layer is formed on the interlayer insulating film. The second electrode layer is formed in the element substrate and overlaps the first electrode in plan view through an interelectrode insulating film. Each of the pixels includes a first region and a second region. The first electrode layer overlaps the second electrode layer in plan view in the first region. Of the first electrode layer and the second electrode layer, only the first electrode layer is formed in the second region. The thickness of the second electrode layer is smaller than the thickness of the first electrode layer.