Light Emitting Device With Transflective Layer And Wide Beam Angle
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Solution Overview
Problem
Light emitting devices, particularly those using nitride semiconductors, face challenges in achieving wide beam angles without additional components like lenses, especially for UV applications where lenses can degrade, and thick sapphire substrates limit luminous efficiency and beam angles.
Innovation Solution
A light emitting device with a thin sapphire substrate and a transflective layer is fabricated, featuring an anti-reflection layer on its side surfaces and an exposed upper surface to enhance light extraction and achieve a wide beam angle of 140° or more without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a lens or additional component is used to increase beam angle, then beam angle is improved, but device complexity and reliability are worsened due to additional components that can degrade or deform
Solution Approach 1:
The patent removes the lens component entirely and instead modifies the substrate itself to achieve wide beam angle. The sapphire substrate is processed with specific surface treatments (convex-concave patterns, inclined surfaces) to directly control light extraction and beam distribution without requiring external optical components.
Solution Approach 2:
The substrate serves dual functions: as the mechanical support structure and as the optical element that controls beam angle. The surface features are formed directly on the substrate, making the substrate self-sufficient for both structural and optical functions, eliminating the need for separate lens components.
2Strength
If a thick sapphire substrate is used, then mechanical strength is improved, but beam angle and luminous efficiency are worsened
Solution Approach 1:
The patent applies different surface characteristics to different regions of the substrate. The top surface features convex-concave patterns with specific inclinations for light extraction, while the bottom surface may have different characteristics. This localized surface treatment optimizes both mechanical integrity and optical performance without requiring overall substrate thinning.
Solution Approach 2:
The patent changes the surface geometry parameters of the substrate, specifically creating convex-concave patterns with controlled inclination angles (e.g., 45-60 degrees). This parameter modification allows the substrate to maintain its thickness for strength while the surface features control light extraction to achieve wide beam angles.
3Loss of energy
If typical surface processing techniques are applied, then light extraction efficiency is improved, but beam angle is not sufficiently increased
Solution Approach 1:
The patent introduces convex-concave surface patterns with curved features on the substrate. These spherical or hemispherical convex regions and concave regions work together to extract light and control its direction. The curvature of these surface features is key to achieving both high extraction efficiency and wide beam angles simultaneously.
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 enables light emitting devices to achieve a wide beam angle and improved luminous efficiency by minimizing light loss and maintaining uniform illumination over various output angles, suitable for UV applications without the need for lenses, thus enhancing reliability.
Implementation Method 1
an anti-reflection layer covering side surfaces of the light emitting structure and the substrate
Implementation Method 2
a transflective layer formed on the sapphire substrate to minimize light loss
Implementation Method 3
the transflective portion may have a different index of refraction from that of the substrate
Data Source
AI summary
A light emitting device including a light emitting structure disposed on one surface of a substrate and a transflective portion disposed on the other surface of the substrate. The transflective portion and the substrate have different indexes of refraction from one another.