Luminescent Light Guide Color Control via Distance-Dependent Reabsorption
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Solution Overview
Problem
Existing lighting devices struggle to efficiently control the color temperature of light sources without increasing the emitting surface area, which is necessary for applications like digital light projection and lamps that require adjustable color gamut and black body dimming.
Innovation Solution
A luminescent concentrator-based lighting device is used, pumped by multiple light sources with spectral overlap between emission and excitation spectra, where the position and intensity of each light source relative to the exit surface are controlled to adjust the color temperature of the emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LEDs are combined to control color temperature, then color control capability is improved, but the emitting surface area increases
Solution Approach 1:
The light guide is segmented into multiple regions along its length, with different LEDs positioned at different locations. Each LED excites the luminescent material in its respective region, and the reabsorption effect creates position-dependent color output. This segmentation allows independent control of color temperature from different spatial zones without requiring a large emitting surface area.
Solution Approach 2:
Instead of controlling color by combining multiple LEDs side-by-side in the same plane (2D arrangement), the invention uses the longitudinal dimension of the light guide (1D arrangement along the length). LEDs are positioned at different distances from one end of the light guide, utilizing the length dimension to achieve color control while maintaining a compact emitting surface.
2Adaptability or versatility
If luminescent material reabsorbs its emitted light to enable color control, then color temperature adjustment is improved, but light intensity is reduced
Solution Approach 1:
The invention exploits changes in the optical parameters of the luminescent material, specifically the reabsorption coefficient, which varies with the path length of light through the material. By controlling the position of LEDs along the light guide, the effective path length and thus the reabsorption effect are controlled, enabling color temperature adjustment. The system optimizes the balance between reabsorption (for color control) and intensity by selecting appropriate LED positions and intensities.
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 approach allows for precise control of the spectral distribution and intensity of the lighting device's output, enabling adjustable color temperature without increasing the emitting surface area, thus maintaining high intensity and flexibility in lighting applications.
Implementation Method 1
The luminescent material in the light guide is configured to reabsorb at least part of its luminescent material light
Implementation Method 2
a luminescent material excitable by the light source light (of the light sources), and configured to provide luminescent material light
Data Source
AI summary
The invention provides a lighting device (100) configured to provide lighting device light (101). The lighting device (100) comprises a plurality of light sources (200) configured to provide light source light (201), the plurality of light sources (200) comprising at least a first light source (210) configured to generate first light source light (211) and a second light source (220) configured to generate second light source light (221). The lighting device further comprises a light guide (300) comprising: a luminescent material (310) excitable by the light source light (201), and configured to provide luminescent material light (311), wherein the luminescent material (310) is configured to reabsorb at least part of its luminescent material light (311), a light exit window (330) for escape of the luminescent material light (311) from the light guide (300), and a plurality of light incoupling areas (320) arranged perpendicular to the light exit window (330) and comprising at least a first light incoupling area (321) configured at a first distance (d1) from the light exit window (330), and a second light incoupling area (322) configured at a second distance (d2) from the light exit window (330). The first light source (210) is configured to provide said first light source light (211) to the first light incoupling area (321), wherein the second light source (220) is configured to provide said second light source light (221) to the second light incoupling area (322), wherein the first distance (d1) is unequal to the second distance (d2). The lighting device further comprises a control unit (500) arranged for controlling the color temperature of the lighting device light by independently controlling the plurality (m) of light sources (200) dependent on the distance of each light source from the light exit window (330).