Flexible Display Wiring via Insulating Film Slits
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Solution Overview
Problem
Flexible organic electroluminescence (EL) display devices face challenges in maintaining electrical connections between wiring lines in bending portions of the frame region, as existing methods primarily focus on preventing inorganic insulating film breakage without ensuring electrical connectivity between adjacent wiring lines.
Innovation Solution
A display device design that includes a resin substrate with a TFT layer, light-emitting elements, and inorganic insulating films, where slits are formed in the insulating films to expose the substrate, allowing wiring lines to connect directly to the substrate and be linked via a third wiring line of the same material and layer, ensuring easy electrical connection between first and second wiring lines in bending portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic insulating film is removed in bending portions to prevent film breakage, then reliability of insulating film is improved, but electrical connection between wiring lines in different bending portions cannot be established
Solution Approach 1:
The inorganic insulating film is segmented by forming slits in bending portions, allowing the film to be discontinuous at bend locations while maintaining integrity in flat regions. This segmentation prevents film breakage during bending while enabling wiring lines to extend through the slits to establish connections.
Solution Approach 2:
The wiring line connection problem is solved by transitioning from a two-dimensional planar connection to a three-dimensional path that extends through the depth of the insulating film via slits. The third wiring line utilizes the vertical dimension by extending from the end face of the flattening film through the slit to connect wiring lines in different bending portions.
2Area of stationary object
If frame region is reduced by bending to meet display requirements, then display area efficiency is improved, but wiring lines in frame region are at risk of disconnection
Solution Approach 1:
Slits are formed in the inorganic insulating film at bending portions before the bending process. This preliminary action prepares the insulating film structure to accommodate bending deformation, allowing wiring lines to extend through the slits and maintain electrical connection even when the frame region is bent to reduce its area.
3Reliability
If multiple wiring lines are provided in bending portions to ensure connectivity, then electrical connection reliability is improved, but device structure becomes more complex
Solution Approach 1:
Multiple functions are merged into the third wiring line: it serves as both a signal transmission line and a connection bridge between wiring lines in different bending portions. The third wiring line is integrated with the existing wiring structure by using the same material and formation process, avoiding additional complex structures while ensuring electrical connectivity.
Data Source
AI summary
A first wiring line and a second wiring line are extended to an upper face of a resin substrate exposed from a slit formed in at least one layer of an inorganic insulating film, a first flattening film is provided within the slit which exposes the upper face of the resin substrate between the portions to which the first wiring line and the second wiring line are extended, and the first wiring line and the second wiring line are electrically connected to each other via a third wiring line provided between an end face of the first flattening film and the upper face of the resin substrate.