Rod-like Light Guide with Longitudinal Grooves for Uniform Luminance
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Solution Overview
Problem
Existing motor vehicle lighting devices with elongated optical fibers experience inhomogeneous luminance on the light-emitting surface due to strong curvatures, which cannot be arbitrarily reduced without altering the light guide's shape or violating design constraints.
Innovation Solution
Incorporating longitudinal grooves on the reflective surfaces of the optical fiber's deflection elements, which scatter light in directions perpendicular to the mean propagation direction, blurring luminance inhomogeneities and enhancing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If strong curvatures are used in the elongated shape of the optical fiber, then the light guide can comply with design specifications and fit available installation space, but inhomogeneities in luminance occur on the light-emitting surface
Solution Approach 1:
The reflective surface is segmented into multiple small reflective facets arranged in a stepped configuration. Each facet is oriented at a different angle to deflect light toward the light-exiting surface, creating a more uniform luminance distribution even when the light guide has strong curvatures.
Solution Approach 2:
Different regions of the light guide have locally optimized reflective surfaces with specific facet orientations tailored to the local curvature requirements. This allows each section to maintain uniform luminance despite varying curvature throughout the overall structure.
2Illumination intensity
If the curvature of the light guide is reduced to improve luminance uniformity, then homogeneous illumination is achieved, but the available installation space or design specifications cannot be met
Solution Approach 1:
The reflective surface is divided into multiple small facets with varying orientations, allowing the light guide to maintain strong curvatures while still achieving uniform luminance through the distributed reflection pattern created by the segmented structure.
Solution Approach 2:
The solution moves from controlling curvature in the primary spatial dimension to controlling light distribution through angular variation in the reflective facet orientations, effectively solving the luminance uniformity problem in a different dimensional approach.
3Illumination intensity
If deflecting elements with reflective surfaces are added to the light guide, then light extraction is improved, but the device complexity increases
Solution Approach 1:
The deflecting elements are integrated directly into the light guide structure, merging the light extraction function with the existing waveguide geometry. This eliminates separate components and reduces overall device complexity while maintaining improved light extraction efficiency.
Solution Approach 2:
The reflective facets serve multiple functions: they extract light from the waveguide, distribute it uniformly across the light-exiting surface, and can be configured to accommodate various curvature requirements. This multi-functionality reduces the need for additional specialized components.
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 achieves a more uniform luminance distribution on the light-emitting surface by scattering light rays, eliminating inhomogeneities and ensuring a homogeneous appearance without altering the light guide's shape or design.
Implementation Method 1
The light guide is configured to transmit the injected light internally via total internal reflections occurring at its interface
Implementation Method 2
the boundary surfaces of the longitudinal grooves scatter incident light also in the direction of the width of the elongated light guide, thereby blurring any existing inhomogeneities in the luminance
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
A lighting device (10) is presented, comprising an elongated light guide (18) and a light source (16) that supplies light (20) to the light guide (18). The light guide (18) is configured to guide the supplied light (20) internally, resulting in a mean direction of light propagation (L) that follows the shape of the light guide. The interface has a light-exiting surface region (26) and a rear region (22) that includes deflecting elements (24) with reflective surfaces (28). The lighting device (10) is characterized by the fact that the rear region (22) has longitudinal grooves (30) that are aligned along the mean direction of light propagation (L) in the reflective surfaces (28).