Phosphor Wheel Color Gamut Control via Pump Power Modulation
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Solution Overview
Problem
Existing illuminating devices with phosphor wheels face challenges in optimizing color gamut and luminous flux, as phosphors with high conversion efficiency often have unfavorable color loci, and varying pump radiation power leads to inefficient operation and high manufacturing costs.
Innovation Solution
A method for operating an illuminating device with a phosphor wheel, where two phosphors with different color loci are irradiated with distinct pump radiation powers, allowing for adjustment of the effective color locus and optimizing the color gamut and luminous flux by varying the pump radiation power during the phosphor wheel's rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single phosphor is used in the phosphor wheel, then the device structure is simple, but the addressable color gamut is limited
Solution Approach 1:
The phosphor wheel is segmented into multiple phosphor segments (first phosphor segment and second phosphor segment) arranged in alternating sequence around the rotation axis. Each segment contains a different phosphor material with distinct conversion characteristics, enabling the system to access a broader color gamut by selectively illuminating different segments during rotation.
Solution Approach 2:
Different phosphor materials are placed at different locations (local positions) around the phosphor wheel circumference. Each location has optimized phosphor properties tailored to specific color requirements, allowing the system to achieve superior color rendering across the visible spectrum by rotating through these locally optimized segments.
2Illumination intensity
If pump radiation power is increased to maximize luminous flux, then the luminous output is high, but the color locus shifts unfavorably and conversion efficiency decreases
Solution Approach 1:
The pump radiation power is dynamically modulated during the phosphor wheel rotation cycle rather than maintaining a constant high power level. The control unit varies the pump radiation power to match the rotational position, providing higher power when high-luminous-flux phosphors are in the irradiation region and reducing power when other phosphors are present, thereby maintaining high average luminous flux while preserving favorable color loci and conversion efficiency.
Solution Approach 2:
The pump radiation power is applied periodically in synchronization with the phosphor wheel rotation. The control unit generates periodic pump radiation pulses that correspond to the passage of specific phosphor segments through the irradiation region, enabling temporal separation of high-power illumination for luminous flux generation and lower-power illumination for color quality maintenance.
3Adaptability or versatility
If different phosphors are arranged on the phosphor wheel, then the color gamut is expanded, but the device complexity and manufacturing cost increase
Solution Approach 1:
Multiple phosphor materials are merged into a single rotating phosphor wheel assembly, combining the functions of what would otherwise require separate stationary light sources. This integration allows the system to achieve broad color gamut coverage through a single compact component, reducing overall system complexity and manufacturing cost compared to using multiple independent phosphor-based light sources.
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 enables flexible control of the color gamut and luminous flux, allowing for a larger addressable color gamut in one mode and maximum luminous flux in another, while maintaining efficient operation and reducing manufacturing costs by optimizing the effective color locus.
Implementation Method 1
a phosphor element which converts the pump radiation emitted thereby and which is arranged at a distance from the pump radiation source. The phosphor element converts the for example ultraviolet or blue pump radiation and emits conversion light having a longer wavelength.
Implementation Method 2
a first phosphor for emitting first conversion light and a second phosphor for emitting second conversion light
Data Source
AI summary
Various embodiments may relate to a method for operating an illuminating device with a pump radiation source for emitting pump radiation, and a phosphor wheel, on which a first phosphor for emitting first conversion light and a second phosphor for emitting second conversion light are provided, in which method the phosphor wheel rotates about a rotation axis and in the process is irradiated with the pump radiation in an irradiation region eccentrically with respect to the rotation axis in such a way that a circular track is irradiated owing to the rotation of the phosphor wheel, wherein during a 360° revolution of the phosphor wheel the first phosphor is irradiated with a first pump radiation power and the second phosphor is irradiated with a second pump radiation power, which is different than the first pump radiation power.