Tiled Display Contact-Hole Structure for Seamless Module Coupling
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Solution Overview
Problem
Large display devices face increased defect rates and reduced productivity due to the number of pixels, and tiled display devices often have a noticeable seam between connected units, disrupting image immersion.
Innovation Solution
A tiled display device design featuring a first substrate with a contact hole and dam, a conductive line with portions on the substrate and dam, and a second substrate with overlapping contact holes, improving thin-film uniformity and eliminating the seam by equalizing external light reflectance between display areas and coupling areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large display device is manufactured with increased number of pixels, then the display size is improved, but the defect rate increases and productivity decreases
Solution Approach 1:
The display device is divided into multiple smaller display modules that are tiled together to form a large display. Each module contains a manageable number of pixels, maintaining low defect rates while achieving large overall display area through the tiled arrangement of multiple modules.
2Area of stationary object
If display devices are connected to form a tiled display, then the display size is improved, but a seam or boundary part appears between devices
Solution Approach 1:
The coupling area between adjacent display modules is designed with specific optical properties (reflectance characteristics) that match the surrounding display areas. This local optimization of optical quality makes the coupling area indistinguishable from the display areas, eliminating the visible seam effect while maintaining the tiled structure for large display area.
3Ease of manufacture
If a conventional contact hole structure is used, then the manufacturing process is simple, but thin-film uniformity deteriorates causing lifting and cracking
Solution Approach 1:
The aspect ratio (width-to-height ratio) of the contact hole is optimized to specific parameter ranges that simultaneously achieve good thin-film uniformity and prevent lifting/cracking. This parameter optimization maintains manufacturing simplicity while resolving the thin-film uniformity issue.
4Reliability
If a separate mask photo process is performed on the lower surface, then conductive line protection is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The photo process steps for the lower surface are merged with the existing photo processes performed on the upper surface. By coordinating the photo patterning steps to simultaneously address both surfaces, the conductive line protection function is achieved without adding separate mask processes, thereby reducing overall device complexity and manufacturing steps.
Data Source
AI summary
A display device includes: a first substrate including a first contact hole and a dam spaced from the first contact hole, a conductive line including a first portion in the first contact hole and a second portion on the dam, a second substrate on the first substrate and the conductive line, the second substrate including a second contact hole overlapping the dam in a thickness direction of the display device, a pad electrode on the second substrate and including a portion in the second contact hole, and a display layer on the second substrate and the pad electrode.