OLED Pixel Layout With Shielding Metal Against Parasitic Coupling
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Solution Overview
Problem
In light emitting display apparatuses, the difference in size of sub-pixels can cause parasitic coupling between the anode of one color and the transistor of another color due to overlapping, leading to issues such as decreased luminance and bright spot defects.
Innovation Solution
A shielding metal is formed at the overlapped portion between the anode of one color and the transistor of another color to prevent electrical coupling, using materials like titanium or aluminum, and is connected to a low-level power line to maintain a constant voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sub-pixels are arranged with different sizes to optimize light emission, then light emission efficiency is improved, but parasitic coupling occurs between anodes and transistors of different colors
Solution Approach 1:
A shielding metal layer is introduced as an intermediary component between the anode of one color and the transistor of another color. This shielding metal acts as a mediator that blocks the parasitic coupling effect while allowing the different-sized sub-pixel arrangement to maintain its light emission efficiency optimization.
Solution Approach 2:
The display structure is segmented by introducing a shielding metal layer that divides the overlapping region into isolated zones. This segmentation prevents the electrical coupling between anodes and transistors of different colors while preserving the functional integrity of each sub-pixel.
2Device complexity
If anode and transistor overlap to accommodate different sub-pixel sizes, then device integration is improved, but parasitic capacitance increases causing bright spot defects
Solution Approach 1:
The shielding metal serves as a protective intermediary that prevents direct electrical interaction between the anode and transistor in overlapping regions. This mediator blocks parasitic capacitance formation while maintaining the integrated layout design.
Solution Approach 2:
The shielding metal is positioned in advance to counteract the parasitic coupling effect before it can occur. By pre-establishing this protective barrier, the design prevents bright spot defects and maintains image quality while preserving device integration.
3Reliability
If shielding metal is added to prevent parasitic coupling, then image quality is improved, but device complexity increases
Solution Approach 1:
The shielding metal layer performs multiple functions simultaneously: it blocks parasitic coupling, prevents bright spot defects, and maintains the integrity of the overlapping sub-pixel structure. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The shielding metal is integrated into the existing multi-layer structure of the display device, merging the shielding function with the existing fabrication processes and layer architecture rather than adding a completely separate system.
Data Source
AI summary
A light emitting display apparatus according to an aspect of the present disclosure may include a first driving transistor and a second driving transistor spaced apart from each other on a substrate, a first anode connected to the first driving transistor and overlapping with the second driving transistor, a second anode connected to the second driving transistor, and a shielding metal between the second driving transistor and the first anode. The second anode may have a smaller area than the first anode, and the shielding metal may reduce a parasitic capacitance associated with the second anode and the first anode.