Pixel Electrode Protrusion for Uniform Display Brightness
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Solution Overview
Problem
In display devices, the existing techniques result in lower brightness at the center of the opening of the cover film compared to the edge due to solute gathering and solvent volatilization during the coating of the light-emitting layer.
Innovation Solution
A display device design featuring a pixel electrode with a flat portion overlapping the light-emitting layer and a surrounding second portion, where the cover film covers the second portion to expose the first portion, forming a flush planar face, ensuring uniform coating and preventing solute segregation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a frame-shaped bank is formed using a cover film overlapping with an edge portion of a pixel electrode, then the light-emitting layer can be formed by coating method, but solutes gather near the end of the bank causing non-uniform brightness
Solution Approach 1:
The pixel electrode is designed with a protruding first portion that extends beyond the cover film opening before coating. This preliminary structural arrangement ensures that the coating solution is applied directly onto the protruding electrode surface, preventing solute gathering at the bank edges and enabling uniform brightness across the light-emitting area.
2Reliability
If the cover film covers the edge portion of the pixel electrode, then the pixel structure is protected, but the brightness at the center becomes lower than at the edge
Solution Approach 1:
The pixel electrode is designed with an asymmetric structure where the first portion protrudes beyond the cover film opening while the second portion remains covered. This asymmetric design allows the protruding portion to receive uniform coating and emit light evenly, while the covered portion provides structural protection, thus resolving the brightness non-uniformity issue.
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
This design enhances uniform brightness across the display region, addressing the issue of lower center brightness and achieving improved light emission efficiency.
Implementation Method 1
a light-emitting element layer including a plurality of light-emitting elements with different luminescent colors
Data Source
AI summary
In a display device including a light-emitting element layer formed on a thin film transistor layer, the light-emitting element layer includes pixel electrodes, a cover film, a light-emitting layer, and a common electrode. The pixel electrodes each include a flat first portion overlapping with the light-emitting layer and a second portion surrounding the first portion. The first portion protrudes toward the light-emitting layer compared to the second portion. The cover film covers the second portion and causes the first portion to expose. An upper face of the first portion and an upper face of the cover film form a flush planar face.