Illumination Device with Oblique LED Injection and TIR Coupling
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Solution Overview
Problem
Existing illumination devices face challenges in efficiently guiding and distributing light from non-parallel source lights, such as LEDs, to achieve uniform and isotropic illumination without the design constraints of incandescent filaments.
Innovation Solution
The use of optical couplers and light guides that receive light from LEDs at oblique angles, directing it through total internal reflection (TIR) to achieve a virtual filament effect, allowing for non-isotropic light emission and enhanced design freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If source lights are oriented obliquely relative to the optical axis to achieve design freedom, then device complexity is reduced and design flexibility is improved, but light distribution uniformity and isotropy deteriorate
Solution Approach 1:
The patent introduces an optical coupler as an intermediary component between the obliquely oriented LED and the light guide. This coupler includes a first optical interface that receives light from the LED and a second optical interface that couples light into the light guide, with light redirecting structures inside the coupler that redirect light from the first interface toward the second interface. This intermediary structure enables non-parallel light injection while maintaining uniform light distribution in the output.
2Ease of manufacture
If non-parallel light injection is used to overcome incandescent constraints, then ease of manufacture is improved and design freedom increases, but light coupling efficiency and distribution quality worsen
Solution Approach 1:
The patent employs parameter changes by varying the refractive index across different regions of the optical coupler. The coupler includes a gradient index structure where the refractive index changes continuously from the first optical interface toward the second optical interface. This gradient index design optimizes light coupling efficiency for oblique injection angles while maintaining uniform light distribution, thereby improving both ease of manufacture and light coupling efficiency 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 configuration enables efficient light distribution and homogenization, providing continuous light output with reduced divergence and increased design flexibility, overcoming the limitations of traditional incandescent sources.
Implementation Method 1
directing it through total internal reflection (TIR) to achieve a virtual filament effect
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An illumination device includes a light source configured to emit, during operation, light with a prevalent direction of propagation different from a direction of an optical axis of the illumination device; and an optical coupler including a transparent material, the optical coupler having an input aperture, an exit aperture and a first side surface and a second side surface arranged between the input aperture and the exit aperture, the exit aperture being centered on the optical axis of the illumination device. The optical coupler receives the emitted light through the input aperture from the light source. Further, the first side surface and the second side surface redirect the received light via total internal reflection (TIR) to the exit aperture. Additionally, the redirected light is issued through the exit aperture.