Light-Guiding Element With Numerical-Aperture Alteration Taper
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Solution Overview
Problem
The use of LEDs in automotive headlamps is limited by the spacing constraints of LED packaging, which prevents the LEDs from being brought into close proximity to achieve the required light intensity, and by the high numerical aperture of individual LEDs, which exceeds the permissible limits for headlamp applications.
Innovation Solution
An illumination assembly featuring a light-guiding element with a numerical-aperture alteration taper, which reduces the numerical aperture from the small end to the large end, allowing for efficient light collection, transmission, and uniform projection, and includes a light-conducting segment for total internal reflection, optimizing light collection and transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LEDs are spaced closely to achieve required light intensity, then illumination intensity improves, but LED packaging constraints prevent close spacing
Solution Approach 1:
A light-guiding element with a numerical-aperture alteration taper is introduced as an intermediary between the LED array and the headlamp optical system. This taper gradually transforms the high numerical aperture light from closely-spaced LEDs into a lower numerical aperture beam suitable for headlamp application, enabling close LED spacing while maintaining optical performance
Solution Approach 2:
The numerical aperture parameter of the light beam is continuously changed along the length of the light-guiding element. The taper geometry is designed to progressively reduce the numerical aperture from the LED source value to the required headlamp value, transforming the optical parameters to resolve the spacing constraint
2Use of energy by moving object
If LED numerical aperture is reduced to meet headlamp requirements, then light collection efficiency improves, but LED packaging and emission characteristics limit NA reduction
Solution Approach 1:
The light-guiding element with numerical-aperture alteration taper serves as an intermediary optical component that decouples the LED emission characteristics from the headlamp optical requirements. It transforms the high-NA light from LEDs into low-NA light suitable for headlamps, improving light collection efficiency without being constrained by LED packaging
Solution Approach 2:
The numerical aperture parameter is transformed from the LED emission value to the headlamp requirement value through the gradual taper geometry. This parameter transformation enables efficient light collection while meeting headlamp optical specifications, independent of LED packaging constraints
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 enhances light collection and transmission efficiency, enabling the achievement of the desired light intensity and uniformity in headlamps by matching the numerical apertures of the light-emitting elements and the light-guiding elements, thereby overcoming the limitations of LED packaging and numerical aperture.
Implementation Method 1
the core and cladding exhibit relative refractive indices that facilitate light propagation by total internal reflection through the light-guiding element
Data Source
AI summary
An illumination assembly includes a light-emitting element that emits light over a light-source numerical aperture and an elongated light-guiding element including opposed incident and emission ends between which ends light propagates by total internal reflection. The light-guiding element includes along a portion of its length a numerical-aperture alteration taper having opposed small and large ends exhibiting, respectively, a small-end numerical aperture and a large-end numerical aperture lower in magnitude than the small-end numerical aperture. The alteration taper is oriented such that the small end is more proximate the incident end than the large end. The incident end is in light-collecting proximity and alignment with the light-emitting element such that light emitted from the light-emitting element over the small-end numerical aperture and received into the small end of the alteration taper is emitted from the emission end of the light-guiding element at an emission numerical aperture lower in magnitude than the small-end numerical aperture.