Display Pixel Bank Structure for External Light Reflection Blocking
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Solution Overview
Problem
Display apparatuses face reduced visibility due to external light reflection, which degrades their performance.
Innovation Solution
The display apparatus incorporates a thin film transistor, a planarization layer, a pixel electrode, a pixel definition layer, and a bank structure with specific geometries and materials to minimize light reflection, including a light blocking layer and a bank light blocking layer with absorbing materials, and uses color filters to reduce external light reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional display structure is used, then the device can be manufactured with standard processes, but external light reflection degrades visibility
Solution Approach 1:
The patent converts the harmful reflection of external light into a beneficial effect by using a bank structure with specific refractive index that redirects reflected light away from the viewer's direction. The bank's geometric shape and material properties transform the harmful reflection into useful light guidance, improving visibility while maintaining the conventional display structure.
Solution Approach 2:
The patent applies local quality by introducing a bank structure with specific optical properties only in the region where light reflection occurs (at the pixel electrode edges), while the rest of the display structure remains conventional. This localized modification targets the reflection problem without requiring complete structural redesign.
2Object-affected harmful factors
If the bank is positioned close to the pixel definition layer, then the structure is compact, but light reflection is not effectively blocked
Solution Approach 1:
The patent positions the bank in a specific spatial dimension - arranged apart from the pixel definition layer in the planar direction but overlapping the contact hole in the vertical dimension. This multi-dimensional positioning allows the bank to block reflected light effectively while maintaining a compact overall structure and avoiding direct contact with the pixel definition layer.
Solution Approach 2:
The patent employs asymmetric positioning where the bank is deliberately placed apart from the pixel definition layer on one side while overlapping the contact hole. This asymmetric configuration optimizes light blocking performance by positioning the bank where it most effectively intercepts reflected light paths without requiring symmetric placement that would increase structural complexity.
3Reliability
If the contact hole is positioned at the center of the exposed pixel electrode, then the electrical connection is optimized, but the planarization layer thickness varies significantly
Solution Approach 1:
The patent applies local quality by having the planarization layer thickness vary locally - thicker in regions away from the contact hole and thinner above the contact hole area. This localized thickness variation maintains reliable electrical connection through the contact hole while compensating for the uneven underlying structure, achieving both electrical performance and manufacturing feasibility.
Solution Approach 2:
The patent uses the planarization layer as a cushioning element that compensates for thickness variations caused by the bank structure and contact hole positioning. By designing the planarization layer with appropriate thickness distribution beforehand, the patent ensures stable electrical connection and uniform upper surface for subsequent layers, preventing manufacturing issues before they occur.
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 enhances visibility by effectively blocking external light reflections and improving the reflective color sense, preventing color bleeding and enhancing the overall display quality.
Implementation Method 1
The bank light blocking layer may include a material absorbing visible light
Data Source
AI summary
A display apparatus for improving a reflective color sense includes a thin film transistor disposed over a substrate, a planarization layer disposed over the thin film transistor, a pixel electrode disposed over the planarization layer and electrically connected to the thin film transistor through a contact hole provided in the planarization layer, a pixel definition layer covering an edge of the pixel electrode to expose a center portion of the pixel electrode, and a bank arranged apart from the pixel defining layer and disposed over an area of a portion of the pixel electrode exposed by the pixel definition layer, the bank overlapping the contact hole when viewed in a direction perpendicular to the substrate.