LED Sidewall Reflective Molding for Light Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED technologies face challenges in effectively reflecting side-emitted light due to impractical reflector designs that block most side light, as they require knife-edge inner edges to capture all light efficiently, which is difficult to produce and maintain.
Innovation Solution
A method of molding a reflective material over the sidewalls of LEDs, ensuring that the inner edges of any surrounding reflector only need to be even with or below the top edge of the reflective material, allowing for a bowl-shaped reflector or a reflective piece that extends above the LED to capture all light without the need for knife-edge edges, using a mixture of silicone and TiO2 as the reflective material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a molded reflector with knife-edge inner edge is used to capture all side light, then light reflection efficiency is improved, but manufacturing complexity and difficulty increase significantly
Solution Approach 1:
The patent applies local quality by placing reflective material only on the sidewalls of the LED package, not on the entire reflector surface. The reflective material (containing TiO2 particles) is selectively applied to the inner sidewalls where light reflection is needed, while other areas remain non-reflective. This localized approach achieves effective light capture without requiring complex knife-edge geometries throughout the entire reflector structure.
Solution Approach 2:
The patent uses composite materials by incorporating TiO2 particles into a reflective material that is then applied to the LED package sidewalls. This composite reflective material provides effective light reflection with a practical, manufacturable geometry. The TiO2 particles dispersed in the material create the reflective properties needed, allowing the use of simpler reflector shapes that are easier to manufacture while maintaining good light capture efficiency.
2Ease of manufacture
If a molded reflector with thick inner edge is used, then manufacturing ease is improved, but side light capture is blocked
Solution Approach 1:
The reflective material is applied locally to the sidewalls of the LED package, creating a reflective surface that extends upward from the base. This localized reflection layer compensates for the thicker inner edge geometry, allowing the reflector to have practical thickness for manufacturing while still capturing side light effectively through the extended reflective surface area on the package sidewalls.
3Loss of energy
If reflective material covers the top surface of the LED, then light reflection is improved, but light emission area is reduced
Solution Approach 1:
The reflective material is selectively applied only to the sidewalls of the LED package, not on the top light-emitting surface. This localized application ensures that all light emitted from the top surface can escape without obstruction, while the sidewall reflection captures and redirects side-emitted light. The method explicitly avoids covering the top surface to maintain full light emission area.
Solution Approach 2:
The reflective coating is segmented to cover only specific regions (sidewalls) while leaving other regions (top surface) uncovered. This segmentation allows different parts of the LED package to have different optical functions: the top surface for light emission and the sidewalls for light reflection, optimizing both light output and side light capture 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
This approach enables practical and efficient light reflection from LEDs, allowing for a larger apparent light source size and smoother brightness profiles, suitable for applications where light from multiple sources must blend together, while maintaining aesthetic appeal and minimizing light absorption.
Implementation Method 1
The reflective material contains the light so that substantially all light is emitted within a well-defined emission area
Implementation Method 2
Some low-angled light rays will reflect off the inner walls of the reflective piece extending above the sidewall reflective material
Data Source
Figure 1~2
Figure 3~7
Figure 8~10
AI summary
A sub mount wafer (36) having mounted on it an array of LED's (10) with a phosphor layer (30), is positioned with respect to a mould (40) having an array of indentions (42). A mixture (44) of silicone an 10%-50%, by weight TiO2, is dispensed between the wafer and the indentions, creating a moulded substantially reflective material. The moulded mixture forms a reflective wall (46) covering the sidewalls of the LED. The reflective material is than cured, and the sub mount wafer is separated from the mould such that the reflective material covering the sidewalls contain the light emitted from the LEO. The sub mount wafer is the diced. A piece (e.g., a reflector (50), support bracket (76), etc) may then be affixed to the sub mount (22) so that the LED protrudes through a centre hole (54) in the piece. The inner edge of the piece is easily formed do that it is located at any height above or below the top surface (32) of the LED.