OLED Pixel Opening Layout for Multi-Nozzle Brightness Uniformity
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Solution Overview
Problem
The uneven brightness issue in OLED display panels due to hardware discrepancies between inkjet printing nozzles, which results in varying sizes of organic light-emitting layers and gaps between ink drops, making it difficult to achieve precise alignment and uniform brightness, especially in bottom-emitting OLED devices.
Innovation Solution
The OLED display panel design includes a substrate with an anode that extends into a pixel opening, where the length of the pixel opening is greater than the length of the anode, allowing for the use of four or more nozzles to print an organic light-emitting layer simultaneously, and optional filling layers to ensure proper contact and alignment, thereby enlarging the operation space for inkjet printing without changing the anode's length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If four or more nozzles are used to print a pixel, then brightness uniformity is improved, but the minimum length of the organic light-emitting layer must be at least 103.5 μm which cannot be realized in bottom-emitting OLED devices
Solution Approach 1:
The patent transitions from a single-dimensional constraint (anode length) to a two-dimensional solution by introducing gaps in the pixel opening along both length and width directions. This allows multiple nozzles to be positioned around the anode in a distributed arrangement, achieving brightness uniformity without increasing the anode length beyond the bottom-emitting OLED limitation.
Solution Approach 2:
The pixel opening is segmented into multiple regions with gaps between adjacent nozzles, allowing each nozzle to deposit ink drops at optimized positions. This segmentation enables four or more nozzles to work simultaneously around the anode, with each contributing to uniform brightness while keeping the total organic light-emitting layer length within acceptable limits.
2Manufacturing precision
If four or more nozzles are used to form ink drops in a pixel, then size discrepancy between organic light-emitting layers is alleviated, but gaps are formed between adjacent nozzles requiring additional space
Solution Approach 1:
The patent applies local quality by creating gaps only in specific locations between adjacent nozzles where they are closest to each other, while maintaining continuous coverage in other areas. This selective gap placement allows for nozzle positioning that minimizes size discrepancy while optimizing the use of available space within the pixel opening.
Solution Approach 2:
The patent uses multiple nozzles as copies of the same printing function, with each nozzle depositing identical organic light-emitting material. By arranging multiple copies (nozzles) around the anode and using gaps to position them optimally, the system achieves uniform brightness and size consistency without requiring excessive total area.
3Illumination intensity
If the pixel opening length is increased to accommodate multiple nozzles, then brightness uniformity is improved, but the anode structure is constrained
Solution Approach 1:
The patent introduces flexibility in the pixel opening structure by allowing variable gap sizes between adjacent nozzles depending on their specific positions and the anode geometry. This dynamic adjustment capability enables optimization of brightness uniformity while adapting the pixel opening to the anode structure, reducing overall device complexity.
Solution Approach 2:
The gaps between adjacent nozzles act as intermediaries that facilitate the positioning and spacing of multiple nozzles around the anode. These gaps provide the necessary space for nozzle placement while maintaining the anode structure intact, serving as a mediating element that enables brightness uniformity without overly constraining the anode design.
Data Source
AI summary
An organic light-emitting diode (OLED) display panel and a method of manufacturing the OLED display panel are provided. The OLED display panel includes: a substrate; an anode disposed on the substrate; and a pixel defining layer disposed on the substrate. The pixel defining layer is provided with a pixel opening. The anode extends into the pixel opening. A length of the pixel opening along a first direction is greater than a part of the anode disposed in the pixel opening along the first direction. Therefore, an operation space for inkjet printing can be enlarged without changing a length of the anode. As such, four or more nozzles can be simultaneously used to print an organic light-emitting layer in a same pixel in bottom-emitting OLED devices, and an uneven brightness issue can be solved.