Non-uniform Diffuser for Uniform LED Light Emission
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Solution Overview
Problem
Conventional LED lamps face issues with heat dissipation and aesthetic concerns due to the placement of phosphor materials, leading to reduced efficiency and acceptance, especially when using remote phosphor arrangements which can result in elevated operating temperatures and undesirable visual characteristics.
Innovation Solution
The use of a separate diffuser layer in combination with remote wavelength conversion materials positioned away from the light source, allowing for efficient heat dissipation and masking of the phosphor appearance, while maintaining high conversion efficiency and reliability, and enabling omnidirectional emission patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If remote phosphor arrangements are used, then heat dissipation is improved, but operating temperature increases
Solution Approach 1:
A transparent thermally conductive intermediate layer is introduced between the remote phosphor and the LED chip. This intermediate layer serves as a thermal bridge that conducts heat away from the phosphor to the LED chip and heat sink, while being transparent to the light wavelengths involved. This mediator resolves the contradiction by providing a path for heat dissipation without requiring the phosphor to be in direct thermal contact with hot components.
2Productivity
If remote phosphor arrangements are used, then conversion efficiency is maintained, but aesthetic appearance deteriorates
Solution Approach 1:
The patent uses a white diffuser material that changes its visual properties based on illumination. When unilluminated, the diffuser appears white and aesthetically pleasing. When illuminated from behind by the LED chip, the diffuser becomes transparent, allowing the remote phosphor to be positioned remotely without compromising conversion efficiency while masking its appearance when not in use.
3Adaptability or versatility
If separate diffuser layer is used, then omnidirectional emission pattern is achieved, but device complexity increases
Solution Approach 1:
The white diffuser material performs multiple functions simultaneously: (1) it masks the appearance of the phosphor and LED chip when unilluminated, (2) it becomes transparent when illuminated to allow efficient light extraction, (3) it diffuses light to create an omnidirectional emission pattern, and (4) it can be integrated into the housing structure. This multi-functionality reduces overall device complexity despite adding the diffuser layer.
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 enhances the reliability and efficiency of LED lamps by effectively dissipating heat and masking the phosphor appearance, resulting in improved performance and consumer acceptance, with the ability to produce omnidirectional emission patterns similar to traditional incandescent bulbs.
Implementation Method 1
A diffuser is arranged to alter the substantially forward emission pattern so that the lamp emits an emission pattern more uniform than the forward emission pattern
Implementation Method 2
remote wavelength conversion materials positioned away from the light source
Data Source
AI summary
A lighting device comprising a light source and a diffuser spaced from the light source. The lighting device further comprises a wavelength conversion material disposed between the light source and the diffuser and spaced from the light source and the diffuser, wherein the diffuser is shaped such that there are different distances between the diffuser and said conversion material at different emission angles. In other embodiments the diffuser includes areas with different diffusing characteristics. Some lamps are arranged to meet A19 and Energy Star lighting standards.