Foldable OLED Encapsulation Film Design for Moisture Protection
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Solution Overview
Problem
Foldable OLED devices are prone to damage from moisture, especially under high temperature and high humidity conditions, leading to issues with display quality and lifespan, and existing encapsulation methods are not effective in preventing damage during the scribing and folding processes.
Innovation Solution
A foldable OLED device design featuring a flexible substrate with an encapsulation film comprising alternating inorganic and organic layers, where the second inorganic layer is wider than the first inorganic layer to cover side surfaces, and the encapsulation film is strategically positioned to avoid damage during scribing and folding, with the ends of the film placed inside the flexible substrate to minimize stress and prevent moisture penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encapsulation substrate of glass is attached onto the emitting diode to prevent moisture penetration, then the emitting diode is protected from moisture, but the display device loses foldable property
Solution Approach 1:
The patent replaces the rigid glass encapsulation substrate with a flexible encapsulation film comprising multiple layers (buffer layer, barrier layer, and protective layer). This flexible film structure maintains moisture protection functionality while enabling the display device to be folded or bent, thus resolving the contradiction between reliability and adaptability.
2Adaptability or versatility
If an encapsulation film is used to enable foldable property, then the display device becomes foldable, but the emitting diode is damaged under high temperature and high humidity conditions
Solution Approach 1:
The encapsulation film is constructed as a composite structure with multiple layers having different functions: a buffer layer (e.g., polyimide) providing mechanical flexibility, a barrier layer (e.g., aluminum oxide or silicon nitride) providing moisture protection, and a protective layer (e.g., acrylic or epoxy) providing environmental resistance. This composite material approach enables both foldable property and reliable emitting diode protection under high temperature and humidity conditions.
Solution Approach 2:
The patent extends the encapsulation film coverage beyond the display region onto the non-display region of the flexible substrate. This dimensional extension allows the encapsulation film to effectively seal the emitting diode area while accommodating the folding mechanics, preventing moisture ingress during folded states.
3Reliability
If the encapsulation film covers the entire non-display region, then moisture protection is maximized, but the bezel width increases
Solution Approach 1:
The encapsulation film is strategically positioned to cover critical areas requiring moisture protection (the display region and portions of the non-display region near the display) while leaving other non-critical areas of the non-display region uncovered. This localized coverage approach maintains effective moisture protection for the emitting diode while minimizing the visible bezel width.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents damage to the emitting diode by minimizing cracks in the encapsulation film, maintaining display quality and extending the lifespan of the foldable OLED device while reducing production costs and allowing for a narrower bezel.
Implementation Method 1
an encapsulation film including an inorganic layer and an organic layer is used instead of the encapsulation substrate. Namely, by using the encapsulation film for preventing moisture penetration into the emitting diode
Implementation Method 2
in the first direction, the second inorganic layer is wider than the first inorganic layer and covers side surfaces of the first inorganic layer
Data Source
AI summary
A foldable organic light emitting display (OLED) device comprises a substrate including a display region and a non-display region, the non-display region located at a periphery of the display region; an emitting diode in the display region; and an encapsulation film covering both the emitting diode and an entirety of the display region, and the encapsulation film covering and a part of the non-display region without covering at least another part of the non-display region.