LED Filament Light Guide Asymmetric Coupling
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Solution Overview
Problem
Existing LED filament lamps lack improved spectral and spatial light distribution, which affects their appearance and user preference.
Innovation Solution
A light emitting device comprising a light guide and a solid-state light source filament with multiple LEDs on opposing sides, where the LEDs emit light with different color points and correlated color temperatures, and only one side is optically coupled to the light guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If LED filaments are placed in a bulb to create an incandescent-like appearance, then the aesthetic appearance is improved, but the spectral and spatial light distribution remains insufficient
Solution Approach 1:
The filament is divided into multiple segments (first and second sides of the carrier) with different LED configurations. One side has LEDs emitting first light with specific color temperature, while the other side has LEDs emitting second light with different color temperature. This segmentation allows independent optimization of spectral properties for each side while maintaining the overall filament structure for aesthetic appearance.
Solution Approach 2:
Different regions of the filament are assigned different optical properties. The first side of the carrier is optically coupled to a light guide that directs first light, while the second side emits second light directly or through a different optical path. This creates localized differences in spectral output and light directionality, improving overall spectral and spatial distribution while preserving the filament's visual appearance.
2Productivity
If both sides of the carrier are optically coupled to the light guide, then light extraction efficiency is improved, but spectral distribution and directional control are compromised
Solution Approach 1:
The optical coupling to the light guide is selectively applied only to one side of the carrier, extracting the light guide function from both sides. This allows the other side to emit light directly or through a different mechanism, preserving spectral diversity and directional control capabilities while still benefiting from light guide-enhanced extraction on the coupled side.
Solution Approach 2:
The optical coupling configuration is made asymmetric by coupling only one side of the carrier to the light guide. This asymmetric design enables different optical pathways for light from each side, allowing independent control over spectral distribution and directional characteristics while maintaining high light extraction efficiency through the light guide on the coupled side.
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 provides improved spectral and spatial light distribution, enhancing the appearance of LED filament lamps and resulting in a more directionally focused and aesthetically pleasing light output.
Implementation Method 1
a light guide and a first solid-state light source filament... the first solid-state light source filament being adapted for, in operation, emitting first solid state light source light... the second solid-state light source light being emitted from a second light exit surface of the first solid-state light source filament
Data Source
AI summary
A light emitting device (1) comprising a light guide (2) and a first solid-state light source filament (3), the first solid-state light source filament (3) comprising a carrier (4) comprising a first side (41) and an opposite second side (42), a first plurality of solid-state light sources (5) being arranged on the first side (41) of the carrier (4), and a second plurality of solid-state light sources (6) being arranged on the second side (42) of the carrier (4). The first plurality of solid-state light sources (5) are adapted for, in operation, emitting first solid state light source light (L1), the first solid state light source light being emitted from a first light exit surface (12a) of the first solid-state light source filament as first output light (L1′), and the second plurality of solid-state light sources being adapted for, in operation, emitting second solid-state light source light (L2), the second solid state light source light being emitted from a second light exit surface (12b) of the first solid-state light source filament as second output light (L2′), the first output light (L1′) being different from the second output light (L2′) in terms of any one or more of different color points and different correlated color temperatures, and only one of the first side (41) and the second side (42) of the carrier (4) is optically coupled to the light guide (2).