Optical Adhesive Layer for Display Device External Light Reflection
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Solution Overview
Problem
Flat panel display devices, such as OLEDs, suffer from external light reflection due to signal lines and driving electrodes, which reduces visibility and requires expensive polarizing plates to mitigate, compromising transmittance and price competitiveness.
Innovation Solution
An optical adhesive layer is introduced between the element substrate and the cover substrate, featuring a first lower adhesive layer in the emission area and a second lower adhesive layer with a different shape in the non-emission area, enhancing optical efficiency while preventing external light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizing plate is used to reduce external light reflection, then visibility is improved, but transmittance is reduced and cost increases
Solution Approach 1:
The adhesive layer is divided into multiple regions with different refractive indices: a first adhesive layer with refractive index 1.4-1.6 in the emission area, and a second adhesive layer with refractive index 1.6-1.8 in the non-emission area. This segmentation allows each region to be optimized for its specific function while working together to reduce overall reflection without compromising transmittance.
Solution Approach 2:
Different regions of the adhesive layer are assigned different optical properties (refractive indices) according to their local requirements. The emission area uses a lower refractive index to maintain light output, while the non-emission area uses a higher refractive index to reduce reflection from signal lines and electrodes, creating local optimization without global compromise.
2Object-affected harmful factors
If a polarizing plate is used to prevent external light reflection, then visibility is improved, but device cost increases
Solution Approach 1:
The patent replaces the expensive polarizing plate with a cost-effective multi-layer adhesive structure. The adhesive layers are formed using standard coating and curing processes already present in OLED manufacturing, eliminating the need for additional expensive optical films while achieving the same anti-reflection function.
Solution Approach 2:
The invention uses a composite adhesive layer structure combining materials with different refractive indices. This composite approach creates an optical gradient that reduces reflection through multiple interfaces, achieving the anti-reflection effect of a polarizing plate but using inexpensive adhesive materials instead of costly optical films.
3Ease of manufacture
If a uniform adhesive layer is used, then manufacturing is simplified, but optical efficiency is reduced due to reflection from signal lines and electrodes
Solution Approach 1:
The adhesive layer is segmented into multiple layers with different refractive indices positioned at different locations. The first adhesive layer (lower refractive index) is positioned over the emission area to minimize impact on light output, while the second adhesive layer (higher refractive index) is positioned over the non-emission area to maximize reflection reduction from signal lines and electrodes.
Solution Approach 2:
The adhesive structure implements local quality optimization by assigning different refractive indices to different spatial regions. This allows the non-emission area to have enhanced anti-reflection properties while the emission area maintains optimal light transmission, thereby improving overall optical efficiency without excessive manufacturing complexity.
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 solution effectively reduces external light reflection and improves optical efficiency, allowing for better visibility without the need for expensive polarizing films, thus enhancing transmittance and luminance while simplifying processing and reducing costs.
Implementation Method 1
the optical adhesive layer includes a first lower adhesive layer disposed so as to overlap an emission area, in which the light-emitting element is disposed, and a second lower adhesive layer formed so as to have a shape different from the shape of the first lower adhesive layer
Implementation Method 2
External light is reflected by the signal lines and the driving electrodes, whereby external visibility is reduced
Data Source
AI summary
Disclosed is a display device capable of reducing the reflection of external light. The display device includes an optical adhesive layer disposed between an element substrate, on which a light-emitting element and a touch sensor are disposed, and a cover substrate, wherein the optical adhesive layer includes a first lower adhesive layer disposed so as to overlap an emission area, in which the light-emitting element is disposed, and a second lower adhesive layer formed so as to have a shape different from the shape of the first lower adhesive layer, the second lower adhesive layer being disposed so as to overlap a non-emission area, excluding the emission area, whereby it is possible to improve optical efficiency while reducing the reflection of external light.