Display Panel Planarization Layers for Signal-Line Corrosion
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Solution Overview
Problem
Display devices are prone to corrosion of signal lines in the non-display area due to moisture and air permeation, which occurs when the thickness of the protection film is insufficient at the top portion of the signal lines.
Innovation Solution
A display device design that includes a first planarization layer covering the inspection signal supply line and a second planarization layer with a higher height in the non-display area, spaced apart from the signal line and overlapping the pad area, to protect the inspection signal supply line from moisture and air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the bezel area or non-display area is minimized to widen the display area, then the display area ratio is improved, but the signal lines become more vulnerable to corrosion by moisture or air
Solution Approach 1:
The patent applies local quality by creating a thicker protection film specifically at the top portion of the signal lines where corrosion is most likely to occur. The protection film thickness is varied locally: thicker (e.g., 1.0-2.0 micrometers) at the signal line top portion and thinner at other areas. This localized thickening provides enhanced corrosion protection exactly where needed without unnecessarily increasing the overall bezel width.
Solution Approach 2:
The patent implements preliminary action by forming the protection film with a predetermined thicker section at the signal line top portion during the manufacturing process. This preventive measure is built into the structure before the device is put into service, proactively protecting the signal lines from moisture and air permeation before corrosion can occur.
2Reliability
If the protection film thickness is increased to prevent signal line corrosion, then the corrosion resistance is improved, but the overall device thickness increases
Solution Approach 1:
The patent resolves this contradiction by applying the thickness increase locally only where corrosion protection is needed - at the top portion of the signal lines. The protection film has a first thickness at the signal line top portion and a second, smaller thickness at other areas. This localized approach provides maximum corrosion protection with minimum overall thickness increase.
Solution Approach 2:
The patent applies partial action by increasing the protection film thickness only partially - specifically at the top portion of the signal lines - rather than uniformly throughout the entire film. This partial thickening provides sufficient protection against corrosion while avoiding unnecessary thickness increase in areas where the signal lines are not present.
Data Source
AI summary
A display device includes: a display panel; a plurality of pixels in a display area of the display panel; an inspection circuit unit and a pad area in a non-display area of the display panel; a data routing line extending from the display area to the inspection circuit unit and the pad area; a first planarization layer extending from the display area to the inspection circuit unit, and on the data routing line; and a second planarization layer extending from the display area to the inspection circuit unit and the pad area, and on the first planarization layer, wherein the inspection circuit unit is adjacent to the pad area and includes an inspection signal supply line configured to supply an inspection signal to the data routing line, and the second planarization layer includes a first area overlapping the inspection signal supply line and a second area overlapping the pad area.