Circular OLED Frame Opening for Crack Prevention
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Solution Overview
Problem
In flexible organic EL display devices, the inorganic film near bending portions experiences non-uniform loading when the display region is circular, oval, or polygonal, leading to potential cracks during bending.
Innovation Solution
A display device design featuring a resin substrate with a TFT layer, light-emitting elements, and frame regions, where the inorganic film is strategically opened and filled with a frame flattening film along the arc of the first frame region at the bending portion, ensuring uniform loading and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inorganic film is continuously formed without opening in the bending portion, then the film provides continuous protection and structural support, but non-uniform loading during bending causes cracks to occur
Solution Approach 1:
The inorganic film is segmented by forming an opening in the bending portion, dividing the continuous film into separate regions. This segmentation allows the film to accommodate bending stresses without developing cracks, as the opening relieves the non-uniform loading that would otherwise cause failure in a continuous film structure.
Solution Approach 2:
The inorganic film structure is made non-uniform by creating a localized opening specifically in the bending portion, while maintaining continuous coverage in other regions. This local modification addresses the specific stress concentration issue in the bending area without unnecessarily compromising the protective function in other areas, optimizing both reliability and structural simplicity.
2Area of stationary object
If the frame region is reduced in size to minimize the display device dimensions, then the overall device size is minimized, but the inorganic film near the bending portion experiences non-uniform loading
Solution Approach 1:
By segmenting the inorganic film through the opening in the bending portion, the structure can accommodate the stress concentrations that arise when the frame region is minimized. The opening allows the film to flex without cracking, enabling smaller frame regions while maintaining film integrity.
Solution Approach 2:
The physical structure of the inorganic film is changed by introducing an opening, which alters how the film responds to mechanical loading. This parameter change (from continuous to discontinuous) allows the film to withstand the non-uniform loading conditions created by reduced frame dimensions and bending operations.
Data Source
AI summary
In an organic electroluminescence (EL) display device, a display region and a first frame region are defined in a substantially circular shape or a substantially oval shape, and in a bending portion, an opening is formed in an inorganic layered film, and a frame flattening film is provided to fill the opening. An end portion of the opening on the display region side is formed along an arc of the first frame region on the bending portion side.