Laser Light Source Coupled Into Total-Reflection Waveguide
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Solution Overview
Problem
Existing LED lighting devices for motor vehicles are limited by low luminance, restricting the length and cross-sectional area of light guides used, which affects the efficiency of light distribution.
Innovation Solution
The use of a laser light source with a light guide that includes a coupling-in surface and a coupling-out surface transverse to the light propagation direction, allowing for high luminance light to be coupled and guided efficiently over long distances, even through compact light guides, with optional phosphor conversion for color adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED light sources are used in combination with light guides, then the lighting device can be implemented with conventional light sources, but the low luminance of LEDs restricts the light guide length and cross-sectional area
Solution Approach 1:
The patent changes the fundamental parameter of light source luminance by replacing conventional LEDs with laser light sources. Laser diodes provide significantly higher luminance (order of magnitude greater), which enables light to be guided over much longer distances and through light guides with smaller cross-sectional areas while maintaining sufficient light intensity at the exit surface.
2Productivity
If conventional LED light sources are used, then the lighting device structure is simpler, but the light distribution efficiency is reduced due to limited light guide dimensions
Solution Approach 1:
By changing the light source parameter from LED to laser diode, the patent achieves superior light distribution efficiency. The high luminance of laser diodes allows for more flexible light guide design, including longer lengths and smaller cross-sections, which improves overall lighting performance and light utilization efficiency in vehicle applications.
3Illumination intensity
If light guides with larger cross-sectional area are used to maintain light intensity, then the light distribution is improved, but the installation space requirements increase
Solution Approach 1:
The patent resolves this contradiction by utilizing the high luminance parameter of laser diodes. This allows the use of light guides with significantly reduced cross-sectional areas while maintaining adequate light intensity at the exit. The compact light guide design reduces installation space requirements in the vehicle while achieving the necessary illumination levels.
4Length of stationary object
If the light guide length is extended to achieve desired light distribution, then the light coverage is improved, but the light intensity loss increases with distance
Solution Approach 1:
The patent overcomes light intensity loss over distance by using laser diodes with extremely high initial luminance. The high starting intensity compensates for attenuation during light propagation through the guide. This enables extended light guide lengths to achieve broader light coverage while maintaining sufficient intensity at the exit surface, as the laser's high luminance budget allows for greater energy loss tolerance.
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 enables the generation of light distributions with sufficient intensity and flexibility in light guide design, allowing for longer, thinner light guides and controlled light color, enhancing light efficiency and distribution in vehicle lighting applications.
Implementation Method 1
a light guide for the totally reflecting conduction of light along a light propagation direction
Implementation Method 2
a decoupling surface is formed in the longitudinal direction of the light guide, which deflects light in the light guide, so that the light exits via an exit surface of the light guide
Implementation Method 3
a converter device comprising in particular an optical attachment and/or a phosphor conversion layer which converts monochromatic laser light into a point white light source or a point light source with a different wavelength
Data Source
Figure 1
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AI summary
The invention relates to a lighting device for a motor vehicle, comprising a light guide (1) for total-reflective guiding of light along a direction of light propagation, wherein the light originates from at least one light source (2) and can be coupled in via at least one coupling surface (3) on one end face of the light guide (1). The light guide further comprises a coupling-out surface (4) disposed along the direction of light propagation for coupling out light that exits from the light guide (1) where the total-reflection condition no longer exists at the exit face (5) disposed along the direction of light propagation. The lighting device of the invention is characterized in that the at least one light source (2), the light from which can be coupled in on the at least one coupling surface (3), is a laser light source.