Embossed Color Filters for OLED Light Extraction
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Solution Overview
Problem
Organic light emitting display devices suffer from reduced visibility and viewing angle characteristics when exposed to external light due to light reflection, with existing solutions like polarizers reducing light extraction efficiency.
Innovation Solution
An organic light emitting display device is designed with a substrate, first electrodes, a pixel defining layer, light emitting layers, a second electrode, and a filter unit including a black matrix and embossed color filters to enhance light extraction and viewing angles, where the black matrix overlaps the pixel defining layer and the embossed color filters are formed with convex or concave lens shapes to control light exposure and improve light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizer is used to prevent external light reflection, then visibility is improved, but light extraction efficiency is reduced
Solution Approach 1:
The patent applies curvature by forming embossed portions (convex or concave lens shapes) on the color filter surface. This curved structure modifies light extraction and viewing angle characteristics without requiring a polarizer, thereby maintaining light extraction efficiency while improving visibility and viewing angle characteristics
Solution Approach 2:
The patent changes the surface geometry parameter of the color filter by creating embossed portions with specific curvature radii and depths. This parameter modification enables control over light extraction efficiency and viewing angle characteristics without introducing additional optical components that would reduce overall light output
2Ease of manufacture
If flat color filters are used, then manufacturing is simple, but light extraction efficiency and viewing angle characteristics are poor
Solution Approach 1:
The patent introduces curvature through embossed portions on the color filter while maintaining compatibility with existing manufacturing processes. The embossed structures can be formed using standard photolithography and reflow techniques, thus preserving ease of manufacture while significantly improving light extraction efficiency and viewing angle characteristics
Solution Approach 2:
The patent applies local quality by creating embossed portions only in specific regions of the color filter corresponding to pixel areas. This localized modification maintains the simplicity of manufacturing for the overall structure while enhancing optical performance precisely where needed - in the light-emitting regions
3Illumination intensity
If embossed color filters are used to improve light extraction, then viewing angle characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the embossed structure formation with the existing color filter manufacturing process. The embossed portions are created as an integral part of the color filter layer through photolithography patterning and thermal reflow, combining multiple functions (color filtering, light extraction enhancement, viewing angle improvement) into a single manufactured component rather than adding separate elements
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
The solution significantly improves visibility and viewing angle characteristics by increasing light extraction efficiency and simplifying the manufacturing process, with the embossed color filters enhancing light emission by up to 115% compared to flat filters.
Implementation Method 1
each color filter comprising at least one embossed portion formed over one of the plurality of openings
Implementation Method 2
The black matrix may be made of a material having a light absorptive property
Data Source
AI summary
An organic light emitting display device including: a substrate; a plurality of first electrodes formed over the substrate; a pixel defining layer (PDL) formed over the substrate, and separating the plurality of first electrodes from one another when viewed in a thickness direction of the display device; a plurality of light emitting layer portions, each of which is formed over one of the plurality of first electrodes; at least a second electrode formed over the plurality of light emitting layer portions; and a filter unit formed over the at least a second electrode. The filter unit includes a black matrix layer having an opening and a plurality of color filters formed over the black matrix layer, and each color filter comprising at least one embossed portion formed over one of the plurality of openings.