Organic EL Display Device Inkjet Edge Control
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Solution Overview
Problem
The challenge in forming organic films through ink jetting lies in the uneven spread of application ink, leading to reduced ink thickness and potential chipping at the edges of the film, making precise edge formation difficult.
Innovation Solution
A display device design featuring a base substrate with switching elements, a flattening film, and a sealing film with a stack of inorganic and organic films, including a recess in the frame region filled with organic film to improve ink spread and prevent chipping, utilizing mask spacers and controlled inkjet ejection timing to ensure uniform film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink jetting is used to form the organic film, then the organic film can be formed with a stack of inorganic and organic films for sealing, but the application ink spreads unevenly at the edge causing reduced ink thickness and chipping
Solution Approach 1:
The flattening film is prepared in advance with a specific edge structure (protrusion or recess) before ink jetting. This preliminary structural preparation guides the ink spread behavior, ensuring uniform thickness at edges while maintaining the sealing film's protective function.
Solution Approach 2:
The flattening film has different structures at different locations: a protrusion at the edge region and a recess at the center region. This local differentiation controls ink spread locally - the edge protrusion prevents ink from spreading too far laterally, while the center recess allows proper ink accumulation, achieving uniform thickness without chipping.
2Ease of manufacture
If the organic resin material is applied through ink jetting, then the sealing film can be formed, but the ink thickness is reduced at the edge producing a chipped organic film
Solution Approach 1:
The flattening film's edge protrusion is formed beforehand to control ink deposition. This preliminary structure ensures that when ink is jetted, it spreads uniformly and maintains adequate thickness, preventing the film from becoming too thin and chipping at the edges.
Solution Approach 2:
The flattening film acts as an intermediary structure between the substrate and the organic film. Its edge protrusion mediates the ink spread process, guiding the application ink to achieve uniform thickness and maintain film integrity throughout the sealing structure.
Data Source
AI summary
An organic EL display device includes an organic EL element disposed on a flattening film, and a sealing film disposed over the organic EL element, a display region, and a frame region disposed around the display region. The frame region includes a plurality of mask spacers. The flattening film has a recess disposed between the display region and the mask spacers adjacent to the display region. The recess is filled with an organic film.