Shielding Pattern Voltage Control for Lateral Leakage Current in OLED Displays
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Solution Overview
Problem
Display devices face issues with color mixing and luminance deterioration due to lateral leakage current caused by organic layers between adjacent pixels, which are formed using a deposition method with a shadow mask, leading to inefficiencies in image display.
Innovation Solution
A display device design that includes a base layer with defined pixel regions and non-pixel regions, a circuit layer with insulating layers and conductive patterns, a light-emitting element layer with a pixel defining structure and shielding patterns, and an input sensing unit, where the shielding pattern is applied with voltage to prevent lateral leakage current and color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an open mask method is used to commonly form organic layers over all pixels, then the manufacturing process is simplified, but lateral leakage current occurs causing color mixing and luminance deterioration
Solution Approach 1:
The pixel defining structure segments the organic layer into separate regions for each pixel by forming insulating walls between adjacent pixels. This segmentation prevents lateral leakage current while still allowing the organic layer to be commonly formed over all pixels using the open mask method, thus maintaining manufacturing simplicity while improving image display quality
Solution Approach 2:
The pixel defining structure introduces local quality differences by creating regions with different electrical properties - the insulating pixel defining layers provide high resistance to lateral current flow, while the organic layer regions maintain their light-emitting properties. This local differentiation prevents color mixing at pixel boundaries while preserving overall manufacturing efficiency
2Reliability
If a shadow mask method is used to form emission layers separately for each pixel, then color mixing is prevented, but mask sag occurs causing manufacturing defects
Solution Approach 1:
The invention extracts the mask component from the manufacturing process by using a pixel defining structure formed through deposition and patterning processes instead of a physical shadow mask. This eliminates mask sag issues while maintaining the ability to prevent color mixing through the insulating pixel defining layers
Solution Approach 2:
The pixel defining structure acts as an intermediary element that provides the necessary electrical isolation between pixels without requiring a shadow mask. The insulating layers in the pixel defining structure mediate the separation of adjacent pixel regions, preventing lateral leakage current while avoiding the defects associated with mask-based methods
Data Source
AI summary
A display device includes a base layer having a plurality of pixel regions and a non-pixel region surrounding the plurality of pixel regions, a circuit layer including a plurality of insulating layers and a plurality of conductive patterns, a light-emitting element layer, and an input sensing unit including a sensing pattern overlapping the non-pixel region. The light-emitting element layer includes a pixel defining structure overlapping the non-pixel region, and a plurality of light-emitting elements. The pixel defining structure includes a step pattern surrounding a portion of each of the plurality of pixel regions. The plurality of conductive patterns include a shielding pattern on the plurality of insulating layers and overlapping at the step pattern in a plan view, at least a portion of the shielding pattern being applied with voltage.