Liquid Crystal Display Cell Gap Uniformity via Dummy Color Filter
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Solution Overview
Problem
Liquid crystal display devices face challenges in maintaining a uniformly created cell gap both in the active area and the peripheral area, which can lead to differences in retardation and transmittance, affecting display quality.
Innovation Solution
The implementation of a liquid crystal display device structure that includes a first substrate with pixel electrodes, a second substrate with a light-shield layer and color filters, a dummy color filter in the peripheral area, and an overcoat layer, along with columnar spacers to create a uniform cell gap, ensuring equal cell gaps in both the active and peripheral areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid crystal display device is designed with standard structure, then manufacturing is simple, but the cell gap becomes non-uniform between active and peripheral areas
Solution Approach 1:
The patent introduces a dummy color filter in the peripheral area before the actual color filters are formed. This preliminary structure serves as a reference for defining the peripheral region and establishing the cell gap height, ensuring uniform cell gap formation across both active and peripheral areas before the main color filter patterning occurs.
Solution Approach 2:
The patent applies different structures to different regions: a dummy color filter is placed only in the peripheral area, while the active area receives the standard color filter structure. This local differentiation allows the peripheral region to have enhanced cell gap control without complicating the overall device structure or affecting the active display area.
2Reliability
If the cell gap is created without dummy color filter, then the manufacturing process is simpler, but the transmittance and retardation become non-uniform
Solution Approach 1:
The dummy color filter is formed as a preliminary structure that defines the peripheral region and establishes the cell gap height reference. This preliminary action ensures that when the actual color filters are formed, the cell gap remains uniform across both active and peripheral areas, guaranteeing consistent transmittance and retardation without adding complex manufacturing steps.
Solution Approach 2:
The dummy color filter acts as an intermediary structure that mediates between the substrate and the actual color filters. It provides a reference plane and height definition that ensures uniform cell gap formation, thereby ensuring display quality consistency without requiring complex additional manufacturing processes.
3Manufacturing precision
If no dummy color filter is used, then device structure is simpler, but differences in retardation and transmittance become visible
Solution Approach 1:
The dummy color filter is selectively placed only in the peripheral area, creating local quality differentiation. This allows the peripheral region to have enhanced cell gap control features without affecting the active display area structure, maintaining manufacturing precision while minimizing additional device complexity to only what is necessary in the peripheral region.
Solution Approach 2:
The dummy color filter serves as a preliminary structural element that establishes the cell gap reference height in the peripheral area. This preliminary structure ensures uniform cell gap formation across the device without requiring complex modifications to the overall layer structure, as it integrates seamlessly with the existing manufacturing process flow.
Data Source
AI summary
According to one embodiment, a liquid crystal display device includes a first substrate including pixel electrodes disposed, respectively, in a first color pixel on one end side of an active area and in a second color pixel on the other end side of the active area, a light-shield layer which surrounds the first color pixel and the second color pixel and extends to a peripheral area surrounding the active area, a first color filter disposed in the first color pixel, a second color filter disposed in the second color pixel, a dummy color filter which is stacked on the light-shield layer in the peripheral area, creates a distance between second color filter and the dummy color filter and is continuous with the first color filter.