OLED Common Voltage Line Width Variation for Dead Space Reduction
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Solution Overview
Problem
In OLED displays, reducing dead space while maximizing the contact area of the common voltage contact portion and minimizing voltage drop in the driving voltage line is challenging, as narrowing the common voltage line increases current density and heat generation, and narrowing the driving voltage line leads to luminance non-uniformity and voltage drop issues.
Innovation Solution
The OLED display design includes a pixel portion with an organic light emitting diode and a periphery portion featuring common voltage lines with a larger width contact portion and driving voltage lines with oblique line portions, where the driving voltage line width inflow is greater than the outflow, and auxiliary lines are used to minimize dead space and voltage drops, with all components formed in the same layer as the gate or data lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the width of the common voltage line is reduced to reduce dead space, then the dead space is reduced, but the contact area of the common voltage contact portion is reduced causing increased current density and heat generation
Solution Approach 1:
The common voltage line is designed with different widths in different sections: a first width in the connection portion and a second width in the contact portion. This local variation allows the contact portion to have sufficient width for adequate contact area and low current density, while the overall line width can be optimized to reduce dead space.
Solution Approach 2:
The common voltage line is divided into multiple sections with different widths - the connection portion has a first width and the contact portion has a second width. This segmentation allows each section to be optimized for its specific function, resolving the contradiction between reducing dead space and maintaining adequate contact area.
2Area of stationary object
If the width of the driving voltage line is reduced to reduce dead space, then the dead space is reduced, but the current density and luminance non-uniformity increase due to severe voltage drop
Solution Approach 1:
The driving voltage line is designed with different widths in different sections, allowing the line to have adequate width in critical sections to minimize voltage drop while reducing width in non-critical sections to reduce dead space.
Solution Approach 2:
The driving voltage line is segmented into sections with different widths, enabling optimization of each section's width for its specific functional requirements, thereby resolving the contradiction between reducing dead space and minimizing voltage drop.
3Temperature
If the contact area of the common voltage contact portion is increased to reduce current density, then heat generation is reduced, but the dead space increases
Solution Approach 1:
The common voltage line has a larger width specifically in the contact portion where adequate contact area is needed to reduce current density and heat generation, while other portions can have smaller widths to minimize dead space.
Solution Approach 2:
The common voltage line is segmented into connection portion and contact portion with different widths, allowing the contact portion to be optimized for thermal performance while the overall structure minimizes dead space.
4Temperature
If the width of the common voltage connection portion is increased to reduce current density, then heat generation is reduced, but the dead space increases
Solution Approach 1:
The common voltage line is designed with a larger width in the connection portion where current density needs to be managed, while other portions maintain smaller widths to minimize dead space.
Solution Approach 2:
The common voltage line is divided into sections with different widths, allowing the connection portion to be optimized for current density management while the overall structure minimizes dead space.
Data Source
AI summary
An organic light emitting diode (OLED) display according to the present invention includes: a pixel portion wherein an organic light emitting diode including a pixel electrode, an organic emission layer, and a common electrode is formed, and a periphery portion surrounding the pixel portion and having a plurality of common voltage lines applying a common voltage to the common electrode. The common voltage lines include a plurality of common voltage pads to which the common voltage is applied from an external source, a common voltage contact portion overlapping an end of the common electrode and contacting the common electrode, a common voltage connection portion connecting a common voltage pad and the common voltage contact portion. A width of the common voltage contact portion is larger than that of the common voltage connection portion.