Foldable Display Spacer Layout for Light-Emitting Layer Adhesion
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Solution Overview
Problem
Foldable or bendable display devices experience peeling phenomena in the light emitting layer due to deformation caused by applied pressure, which degrades the display quality.
Innovation Solution
A display device incorporating a spacer structure assembly with at least two spacers having different separation distances at different areas, implemented in an inverse tapered shape, to improve adhesion and reduce bank width, thereby minimizing deformation and enhancing resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spacers with uniform separation distance are used, then manufacturing is simpler, but adhesion of the light emitting layer deteriorates under pressure causing peeling
Solution Approach 1:
The spacer structure is divided into multiple spacers arranged in rows and columns rather than using a single uniform spacer. This segmentation allows different regions to have different separation distances, with first spacers having a first separation distance and second spacers having a second separation distance greater than the first. This segmented approach improves adhesion by creating varied mechanical anchoring points while maintaining manageable manufacturing complexity through systematic arrangement.
Solution Approach 2:
Different regions of the display device are assigned different spacer configurations. Specifically, spacers in different rows and columns have different separation distances tailored to local requirements. The first separation distance is used in certain regions while the second greater separation distance is used in other regions, optimizing adhesion locally rather than applying a uniform solution across the entire device.
2Reliability
If bank width is increased to improve structural stability, then deformation resistance improves, but resolution deteriorates
Solution Approach 1:
The bank structure is supported by multiple spacers arranged in rows and columns rather than relying on a single wide bank. This segmentation of support functions allows the bank width to be reduced while maintaining overall structural stability through the distributed spacer network, thereby improving resolution without sacrificing deformation resistance.
Solution Approach 2:
Instead of relying solely on increasing bank width (one dimension) for stability, the invention introduces a two-dimensional array of spacers at different separation distances. This dimensional transition provides structural support through vertical and horizontal distribution of spacers, enabling thinner banks that improve resolution while maintaining deformation resistance through the multi-dimensional spacer architecture.
3Ease of manufacture
If uniform spacer separation distance is used, then manufacturing process is simpler, but peeling resistance under pressure deteriorates
Solution Approach 1:
Different separation distances are applied in different regions of the spacer structure. First spacers have a first separation distance while second spacers have a second separation distance greater than the first. This local variation in separation distance is implemented through region-specific photolithography masks, balancing manufacturing feasibility with improved peeling resistance through varied mechanical interlocking.
Solution Approach 2:
The separation distance parameter is varied across different spacer regions rather than maintaining a uniform value. By changing this critical geometric parameter from a constant to a spatially varying value, the invention improves peeling resistance through diversified stress distribution while maintaining ease of manufacture through systematic parameter control during the photolithography process.
Data Source
AI summary
A display device can include a thin film transistor disposed on a substrate, a bank disposed on the thin film transistor, an anode electrode disposed on the substrate, an organic layer disposed on the anode electrode, and a spacer structure assembly disposed on the bank. The bank is disposed on the anode electrode. The display device further includes a folded area and a flat area. In the folded area, the spacer structure assembly can include at least two folded area spacers including a first folded area spacer and a second folded area spacer spaced from each other on the bank.