Planar Light Guide Diffuse Area for Homogeneous Color Distribution
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Solution Overview
Problem
Conventional lighting devices with flat light guides produce inhomogeneous color patterns when irradiating light of different colors due to light guidance and decoupling based on total internal reflection, resulting in an uneven light distribution visible to users.
Innovation Solution
Incorporating a diffuse area between the light in-coupling and out-coupling structures in the flat light guide, which scatters light to achieve a homogeneous color and brightness distribution with minimal light loss, using a design that is simple and compatible with existing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light guidance and decoupling based on total internal reflection is used in the light guide, then light can be guided efficiently through the light guide, but an inhomogeneous color pattern results when light of different colors is irradiated
Solution Approach 1:
The light guide is segmented into two distinct functional areas: a first area with high reflectivity for efficient light guidance, and a second area with reduced reflectivity (diffuse area) for light mixing and color homogenization. This segmentation allows each area to perform its specialized function optimally without interfering with the other.
Solution Approach 2:
Different areas of the light guide are assigned different optical properties: the first area has high reflectivity to guide light efficiently, while the second area has reduced reflectivity and increased diffusion to mix light of different colors. This local differentiation of properties resolves the contradiction between efficient light guidance and color homogeneity.
2Manufacturing precision
If a diffuse area is added to the light guide to achieve homogeneous color distribution, then color homogeneity improves, but the device complexity increases
Solution Approach 1:
The diffuse area is integrated directly into the light guide structure itself, merging the light guidance function and the light diffusion function into a single component. This eliminates the need for separate diffusion elements or additional components, thereby reducing device complexity while still achieving color homogeneity.
Solution Approach 2:
The light guide serves multiple functions: it guides light through the first area with high reflectivity, mixes and homogenizes light colors in the second diffuse area, and directs the homogenized light toward the light exit surface. This multi-functionality within a single component simplifies the overall device structure.
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 results in a more uniform and homogeneous light emission with negligible light losses, enhancing the color homogeneity and brightness distribution, while maintaining a compact and cost-effective production process.
Implementation Method 1
The planar light guide is set up in particular to guide light coupled into it through the at least one peripheral light coupling surface by means of total reflection on its free surface
Implementation Method 2
Incorporating a diffuse area between the light in-coupling and out-coupling structures in the flat light guide, which scatters light to achieve a homogeneous color and brightness distribution
Data Source
Figure 1~2
Figure 3
AI summary
A lighting device (1) comprises a planar light guide (2) with at least one edge-side light coupling surface (3) and at least one light coupling structure (4) on one of its flat sides (5a), at least one first light source (7a, 7b, 7c) configured for coupling light of a first color (Lr, Lg, Lb) into the light coupling surface (3), and at least one second light source (7a, 7b, 7c) spatially offset from the first, configured for coupling light of a second color (Lr, Lg, Lb) into the same light coupling surface (3), wherein a diffuse region (4a) is present in the light guide (2) between the light coupling surface (3) and the light coupling structure (4). A vehicle (F) comprises at least one lighting device (1).In one method, differently colored light (Lr, Lg, Lb) is coupled from locally different locations into a light coupling surface (3) of a planar optical fiber (2) and then passes through a diffuse area (8) of the optical fiber (8) before being coupled out by means of a light coupling structure (4).