Uneven Reflective Surfaces on Pixel Electrodes for Display Anti-Reflection
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Solution Overview
Problem
Self-emission display devices like organic EL displays face significant degradation in display quality due to external light reflection, leading to poor luminous efficiency, especially when a circular polarizer is used to mitigate this issue, as it results in the loss of half or more of the emitted light.
Innovation Solution
The display device incorporates a base substrate layer, a thin film transistor layer, and a light-emitting element layer with pixel electrodes, a common edge cover, and a reflective surface having an uneven shape in the non-light-emitting regions to redirect external light away from the viewing direction, eliminating the need for a circular polarizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circular polarizer is attached to the display device surface to prevent external light reflection, then display quality is improved, but luminous efficiency deteriorates due to loss of half or more of emitted light
Solution Approach 1:
The pixel electrode surface is segmented into light-emitting regions and non-light-emitting regions. The non-light-emitting regions are equipped with reflective surfaces having uneven shapes that redirect external light away from the viewing direction, while the light-emitting regions maintain flat surfaces for efficient light extraction. This segmentation allows different regions to serve different functions without compromising overall performance.
Solution Approach 2:
Different surface properties are applied to different regions of the pixel electrode. The light-emitting regions have flat surfaces optimized for light extraction efficiency, while the non-light-emitting regions have uneven reflective surfaces optimized for blocking external light reflection. This local differentiation resolves the contradiction by applying the appropriate surface quality to each functional region.
2Object-affected harmful factors
If a circular polarizer is used to block external light reflection, then display quality in bright environments is improved, but device complexity increases
Solution Approach 1:
The circular polarizer component is extracted and removed from the display structure. Instead, the anti-reflection function is achieved through the uneven reflective surfaces formed directly on the pixel electrode in non-light-emitting regions. This eliminates the need for additional optical layers and simplifies the overall device structure.
Solution Approach 2:
The pixel electrode serves multiple functions: it acts as both the light-emitting component and the anti-reflection component. The uneven reflective surfaces on the non-light-emitting regions provide the anti-reflection function that would otherwise require a separate circular polarizer, thereby reducing device complexity while maintaining effectiveness.
3Object-affected harmful factors
If the entire pixel electrode surface is made reflective to block external light, then display quality is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The pixel electrode surface is divided into distinct light-emitting regions and non-light-emitting regions. Only the non-light-emitting regions are equipped with uneven reflective surfaces for blocking external light, while the light-emitting regions maintain flat surfaces for efficient light extraction. This segmentation ensures that the anti-reflection measure does not compromise light extraction efficiency.
Solution Approach 2:
Reflective properties are applied locally only to the non-light-emitting regions where they are needed for blocking external light. The light-emitting regions maintain their original flat surface quality optimized for light extraction. This localized application of reflective properties resolves the contradiction between anti-reflection and light extraction efficiency.
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
This configuration effectively reduces display quality degradation caused by external light reflection without using a circular polarizer, maintaining high luminous efficiency by reflecting external light in a direction different from the incident light, thereby enhancing the overall display performance.
Implementation Method 1
a reflective surface having an uneven shape is provided in the non-light-emitting region
Data Source
AI summary
A display device includes: a base substrate layer; a thin film transistor layer provided on the base substrate layer; and a light-emitting element layer provided on the thin film transistor layer, the light-emitting element layer including a plurality of pixel electrodes, a common edge cover, a plurality of light-emitting function layers, and a common electrode layered in order corresponding to a plurality of subpixels constituting a display region, wherein the edge cover covers a peripheral edge portion of each of the pixel electrodes, in each of the subpixels, a portion of the plurality of pixel electrodes exposed from the edge cover constitutes a light-emitting region, and a portion of the plurality of pixel electrodes overlapping the edge cover constitutes a non-light-emitting region, and a reflective surface having an uneven shape is provided in the non-light-emitting region.