Flexible Display Insulating Sheet with Step Portions and Walls
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Solution Overview
Problem
Conventional flexible display configurations face challenges in preventing shorts between wiring lines at different potentials in curved regions due to insufficient rigidity and potential remnants of wiring layers during dry etching processes.
Innovation Solution
A display device design featuring a flexible display panel with an insulating sheet having varying film thickness regions and step portions, along with an insulating wall and conductors, to electrically connect the pixel array and drive portions while preventing shorts, utilizing a polyimide or inorganic insulating material with silicon oxide and silicon nitride layers, and a step reducing layer to manage film thickness and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the film thickness of the insulating sheet is made thin in the curved region, then the rigidity is reduced and flexibility is improved, but step portions are generated that may cause shorts between wiring lines
Solution Approach 1:
The insulating sheet has different film thicknesses in different regions: a first film thickness in the curved region and a second film thickness (greater than the first) in regions where wiring lines are formed. This local variation in thickness provides flexibility where needed while maintaining sufficient insulation height where wiring lines are present, preventing shorts without compromising flexibility.
2Reliability
If the insulating sheet thickness is increased to prevent shorts, then reliability improves, but the rigidity increases and flexibility deteriorates
Solution Approach 1:
The insulating sheet has different film thicknesses in different regions: a first film thickness in the curved region and a second film thickness (greater than the first) in regions where wiring lines are formed. This local variation in thickness provides flexibility where needed while maintaining sufficient insulation height where wiring lines are present, preventing shorts without compromising flexibility.
3Manufacturing precision
If dry etching is used to process wiring lines, then manufacturing precision is improved, but remnants of wiring layer may remain at step portions causing shorts
Solution Approach 1:
An insulating wall is formed in advance at the step portion between different film thickness regions. This preliminary insulating structure prevents wiring layer remnants from causing shorts between adjacent wiring lines, addressing the short prevention issue before the dry etching process is completed.
Solution Approach 2:
The insulating wall acts as an intermediary barrier at the step portion, physically separating adjacent wiring lines and preventing electrical connection through wiring layer remnants. This mediator structure resolves the conflict between precise dry etching and short prevention.
Data Source
AI summary
A display device according to an embodiment of the present invention includes: an insulating sheet provided from a display region to a drive portion forming region, including, in a curved region, a first film-thickness region having a first film thickness thinner than a film thickness at the display region and a film thickness at the drive portion forming region, and including a first step portion disposed between the display region and the first film-thickness region and a second step portion disposed between the drive portion forming region and the first film-thickness region, first and second wiring lines crossing the first step portion and the second step portion above the insulating sheet and electrically connecting a pixel array portion with a drive portion, and an insulating wall extending from the first step portion to the second step portion between the first wiring line and the second wiring line.