DBR LED Structure for Consistent RGB Emission Angles
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Solution Overview
Problem
The existing mini RGB lamp beads face a challenge in achieving consistent light-emitting angles due to the disparity in light-emitting angles between red, green, and blue LED chiplets, which limits the improvement of optical performance such as image resolution.
Innovation Solution
A light-emitting diode with a semiconductor light-emitting sequence layer and a DBR structure, where the DBR structure includes alternating first and second sublayers with different materials, optimizing the optical thickness of each sublayer to ensure that in at least 40% of the stacked-layer structures, one sublayer's thickness is greater than 1/3 and the other's is less than 1/3 of the central wavelength, thereby reducing the light-emitting angles of blue and green LEDs to match those of red LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional DBR structure is used in mini RGB LED chiplets, then the light-emitting angle can be increased to 140 degrees, but the optical performance deteriorates due to excessively large light-emitting angles
Solution Approach 1:
The patent applies parameter changes by modifying the optical thickness of DBR sublayers from the conventional uniform design to a non-uniform design where at least one sublayer has optical thickness greater than λ/3 and at least one adjacent sublayer has optical thickness less than λ/3. This parameter variation in the DBR structure enables precise control of the light-emitting angle while maintaining optimal optical performance, resolving the contradiction between increasing light-emitting angle and preserving optical quality.
2Manufacturing precision
If the light-emitting angle of red light chiplet is kept small, then the manufacturing precision is maintained, but the image resolution deteriorates due to inconsistency with blue and green light chiplets
Solution Approach 1:
The patent applies local quality by implementing different optical thickness configurations in different sublayers of the DBR structure. Specifically, certain sublayers have optical thickness greater than λ/3 while adjacent sublayers have optical thickness less than λ/3, creating localized variations in optical properties. This enables the red light chiplet to achieve a light-emitting angle consistent with blue and green chiplets, thereby improving image resolution while maintaining manufacturing precision.
3Device complexity
If the optical thickness of all DBR sublayers is made uniform, then the device complexity is reduced, but the light-emitting angle control deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the DBR structure into multiple sublayers with different optical thickness characteristics. Instead of using uniform thickness throughout, the structure is segmented into sublayers where at least one has optical thickness >λ/3 and at least one adjacent sublayer has optical thickness <λ/3. This segmentation enables precise control of light-emitting angle while maintaining manageable device complexity through systematic layer design.
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 design enhances the optical performance of mini RGB lamp beads by making their light-emitting angles consistent, thereby improving image resolution and maintaining high brightness intensity for small-angle light, while preventing excessive thickness-related issues like chip warpage.
Implementation Method 1
the DBR structure includes m first sublayers and n second sublayers stacked in an alternating manner... In each of at least 40% of the groups of the stacked-layer structures, an optical thickness of one of the first sublayer and the second sublayer is greater than 1/3 of a central wavelength of light emitted by the semiconductor light-emitting sequence layer
Implementation Method 2
DBR structure (distributed Bragg reflector)... the DBR structure reduces the light-emitting angles of blue and green LEDs
Data Source
AI summary
A light-emitting diode includes a semiconductor light-emitting sequence layer and a DBR structure. The DBR structure is disposed on a first surface of the semiconductor light-emitting sequence layer. The DBR structure includes m first sublayers and n second sublayers stacked in an alternating manner, wherein m and n are positive integers larger than 1. Materials of the first sublayers and the second sublayers are different. One first sublayer and one second sublayer adjacent to each other are defined as a group of a stacked-layer structure. In each of at least 40% of the groups of the stacked-layer structures, an optical thickness of one sublayer is greater than ⅓ of a central wavelength of light emitted by the semiconductor light-emitting sequence layer and an optical thickness of the other sublayer is less than ⅓ of the central wavelength of the light emitted by the semiconductor light-emitting sequence layer.