Active Matrix Substrate Cutaway for Slit-End Alignment Control
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Solution Overview
Problem
In liquid crystal display devices with ultra-high definition pixel sizes (1000 ppi to 1200 ppi) using a COA structure, the alignment disorder of the liquid crystal layer occurs at the end portion of slits in the transparent electrodes, leading to image sticking and afterimages due to overlapping with an electrically floating antireflection layer.
Innovation Solution
The active matrix substrate design includes a second transparent electrode with a slit and an antireflection layer that has a cut-away portion to avoid overlapping with the slit ends, using an inorganic protection film and layered metal layers to suppress alignment disorder and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is increased to ultra-high definition (1000-1200 ppi), then the display resolution is improved, but the slit end portion overlaps with the antireflection layer causing alignment disorder
Solution Approach 1:
The antireflection layer is extracted or removed from the overlapping region at the slit end portion. The patent specifically removes the antireflection layer in a region that overlaps with the end portion of the slit to prevent alignment disorder, while maintaining the antireflection layer in other regions for its intended function.
Solution Approach 2:
The antireflection layer is selectively removed only from the specific region where it causes problems (overlapping with slit end portion), while being maintained in other regions. This creates local differentiation in the structure, preserving antireflection functionality where needed while eliminating alignment issues where they occur.
2Reliability
If the antireflection layer is removed to prevent alignment disorder, then liquid crystal alignment is improved, but the antireflection function is reduced
Solution Approach 1:
The antireflection layer is selectively extracted only from the problematic overlapping region at the slit end portion, while being preserved in other regions. This partial removal approach maintains the overall antireflection function of the display while eliminating the specific alignment disorder caused by overlap.
Solution Approach 2:
The structure transitions from a uniform antireflection layer to a non-uniform structure where the layer is present in some regions and absent in others. The local quality principle allows the antireflection layer to exist where it provides benefit while being removed where it causes harm to liquid crystal alignment.
3Reliability
If additional steps are added to prevent overlap, then alignment quality is improved, but manufacturing complexity increases
Solution Approach 1:
The antireflection layer is removed in advance during the manufacturing process, before the liquid crystal alignment issue can occur. By performing the removal action preliminarily during fabrication, the patent avoids the need for additional corrective steps after assembly, thereby preventing alignment disorders without significantly increasing overall manufacturing complexity.
Data Source
AI summary
An active matrix substrate includes: a base substrate; a plurality of thin film transistors provided on the base substrate corresponding to a plurality of subpixels; color filters provided on the plurality of thin film transistors, respectively, and including colored layers of predetermined colors corresponding to the plurality of subpixels, respectively; a first transparent electrode provided above the color filters; a second transparent electrode provided on the first transparent electrode with an inorganic protection film interposed therebetween, the second transparent electrode including a slit having a belt shape; and an antireflection layer provided in a belt shape on the inorganic protection film in a boundary portion between the colored layers of different colors among the predetermined colors and including a first metal layer, an intermediate layer, and a second metal layer layered in order. The antireflection layer is provided with a cut-away portion not overlapping an end portion of the slit.