Multi-layer Bank Structure for Ink Overflow Control in Display Devices
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Solution Overview
Problem
Display devices face challenges in preventing ink, including light emitting elements, from overflowing over light emitting areas, which can lead to defects such as bright spots, dark spots, and film tearing due to uneven ink distribution and potential short circuits between electrodes.
Innovation Solution
The use of bank pattern layers, including first, second, and third bank pattern layers, which are strategically designed to create a stepped structure and define emission areas, preventing ink overflow by varying thickness and width, and ensuring uniform ink distribution across subpixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bank pattern layers are used to prevent ink overflow, then ink distribution uniformity is improved, but device structure complexity increases
Solution Approach 1:
The bank structure is divided into multiple bank pattern layers (first bank pattern layer, second bank pattern layer, third bank pattern layer) with different thicknesses and positions. Each layer serves a specific function in controlling ink flow at different stages, segmenting the ink containment function into manageable parts that collectively achieve uniform ink distribution while maintaining manufacturability.
Solution Approach 2:
The bank pattern layers are arranged in multiple vertical dimensions with varying thicknesses (first bank pattern layer with first thickness, second bank pattern layer with second thickness, third bank pattern layer with third thickness). This multi-dimensional arrangement creates a stepped structure that controls ink overflow in the vertical direction while defining emission areas horizontally, resolving the contradiction between precision and complexity.
2Reliability
If thicker bank pattern layers are used to prevent ink overflow, then ink containment capability is improved, but electrode short circuit risk increases
Solution Approach 1:
Different bank pattern layers have different thicknesses tailored to their specific locations and functions. The first bank pattern layer has a first thickness, the second bank pattern layer has a second thickness, and the third bank pattern layer has a third thickness. This local differentiation allows each layer to provide appropriate containment capability at its location without creating excessive height that could cause short circuits, thus resolving the contradiction between containment capability and short circuit risk.
Solution Approach 2:
The ink containment function is segmented across multiple bank pattern layers with progressively different thicknesses. Rather than using a single thick bank layer that could cause short circuits, the containment function is distributed across multiple thinner layers, each contributing to overall ink containment while maintaining safe distances from electrodes.
3Manufacturing precision
If multiple bank pattern layers are used to define emission areas, then emission area definition precision is improved, but manufacturing process complexity increases
Solution Approach 1:
The emission area definition is segmented across multiple bank pattern layers, with each layer contributing to the overall emission area boundary. The first, second, and third bank pattern layers work together in sequence to precisely define the emission area, dividing the complex definition task into simpler sequential steps that improve precision while managing manufacturing complexity.
Solution Approach 2:
The bank pattern layers are formed in a predetermined sequence (first bank pattern layer, then second bank pattern layer, then third bank pattern layer) with each layer prepared in advance to perform its specific function. This preliminary arrangement of layers with different thicknesses and positions enables precise emission area definition while streamlining the manufacturing process through systematic layer formation.
Data Source
AI summary
A display device includes a substrate, a via layer disposed on the substrate, first bank pattern layers, a second bank pattern layer and third bank pattern layers, which are disposed on the via layer, a first electrode and a second electrode spaced apart from each other, a light emitting element disposed between the first electrode and the second electrode, and a bank layer disposed on the first bank pattern layers and the third bank pattern layers and defining an emission area. The third bank pattern layers extend in a first direction and spaced apart from each other, the first bank pattern layers and the second bank pattern extend from the third bank pattern layers in a second direction intersecting the first direction, and a thickness of the first bank pattern layers is smaller than a thickness of the third bank pattern layers.