Display Substrate Pixel Layout for OLED Brightness Uniformity
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Solution Overview
Problem
Existing display technologies using OLEDs face issues with inconsistent brightness between sub-pixels due to differences in parasitic capacitance, particularly in GGRB pixel arrangements, affecting display quality.
Innovation Solution
The display substrate design includes a conductive block in specific sub-pixels to compensate for parasitic capacitance differences by overlapping the anode of the light emitting device with the gate electrode of the drive transistor, reducing the area of overlapping regions and incorporating a conductive block to equalize electrical environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a metal mask is used to form the emission layer in the vacuum deposition process, then the emission layer can be formed with good uniformity and quality, but the metal mask may remain attached to the emission layer causing contamination and requiring additional cleaning steps
Solution Approach 1:
The patent extracts the metal mask from the vacuum deposition process entirely by replacing it with a photomask. The photomask is a transparent substrate with patterned opaque regions that allows light to pass through during photopolymerization, eliminating the need for metal mask attachment and subsequent cleaning operations while maintaining precise emission layer formation
Solution Approach 2:
The patent replaces the mechanical vacuum deposition process with a photochemical polymerization process. Instead of using a metal mask in vacuum to deposit material mechanically, the invention uses a photomask with UV light to selectively polymerize monomers, substituting a mechanical system with an optical-chemical system that avoids contamination
2Manufacturing precision
If a complex multi-step process is used to form the emission layer with high precision, then the emission layer quality is improved, but the manufacturing time and process complexity increase
Solution Approach 1:
The patent combines multiple separate steps (substrate preparation, monomer coating, photomask alignment, UV irradiation, and emission layer formation) into a single integrated photopolymerization process. The monomer layer is prepared on the substrate, the photomask is placed directly on top, and UV light simultaneously patterns and forms the emission layer in one operation, eliminating multiple handling and processing steps
Solution Approach 2:
The patent performs preliminary preparation of the monomer layer on the substrate before the actual emission layer formation. The monomer is coated and dried in advance, creating a ready-to-polymerize layer that can be quickly converted to the emission layer through simple UV irradiation, reducing the time required during the critical patterning step
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 brightness consistency among sub-pixels, improving overall display quality by minimizing parasitic capacitance variations and ensuring uniform light emission.
Implementation Method 1
irradiating a monomer layer with a photomask thereon with ultraviolet light
Implementation Method 2
vacuum deposition process
Data Source
Figure 1~2
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AI summary
A display substrate, comprising a first sub-pixel, a second sub-pixel, and a third sub-pixel and a fourth sub-pixel, which emit rays of light of the same color, wherein at least one sub-pixel comprises a pixel driving circuit and a light-emitting device, and the pixel driving circuit comprises a driving transistor; the orthographic projection of an anode of the light-emitting device in the third sub-pixel on a base and the orthographic projection of a gate electrode of the driving transistor in the third sub-pixel on the base have a first overlapping region; the orthographic projection of an anode of the light-emitting device in the fourth sub-pixel on the base and the orthographic projection of a gate electrode of the driving transistor in the fourth sub-pixel on the base do not have an overlapping region or have a second overlapping region, and the area of the second overlapping region is smaller than the area of the first overlapping region; and the fourth sub-pixel, or the first sub-pixel or the second sub-pixel adjacent to the fourth sub-pixel comprises a conductive block, and the orthographic projection of the conductive block on the base and the orthographic projection of the gate electrode of the driving transistor in the fourth sub-pixel on the base have a third overlapping region.