Phosphor Wheel Light Scattering for White Light Uniformity
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Solution Overview
Problem
Existing phosphor wheels in DLP projectors face challenges in producing white light due to the mismatch between the spatial distribution of phosphor emission and direct blue laser light, which hinders effective white light production.
Innovation Solution
Incorporating a phosphor wheel with a luminescent layer comprising a mixture of phosphors and high reflectivity light scattering materials dispersed in a binder, which scatters unconverted blue light to match the spatial distribution of phosphor emission, thereby combining direct blue light with converted phosphor emission to produce white light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor wheel uses separate color segments with corresponding light paths and color-mixing hardware, then different color lights can be combined to yield white light, but device complexity increases
Solution Approach 1:
The patent merges multiple color segments (blue, green, yellow, red phosphors) into a single integrated phosphor wheel structure that rotates to present different colors to a single light path, eliminating the need for separate light paths and complex color-mixing hardware while maintaining white light output
Solution Approach 2:
The single phosphor wheel structure performs multiple functions by sequentially presenting different color segments (blue, green, yellow, red) to the same light path, allowing one component to replace what would traditionally require multiple separate components and light paths
2Productivity
If high power blue light source is used to stimulate phosphor wheel, then white light output efficiency improves, but heat distribution becomes problematic
Solution Approach 1:
The patent employs a rotating phosphor wheel that dynamically distributes the heat generated by high power blue light sources across its circumference over time, allowing high power operation while preventing localized overheating through continuous rotation and heat redistribution
3Productivity
If phosphor wheel rotates rapidly to produce different colors in time sequence, then white light can be generated, but spatial uniformity of light distribution deteriorates
Solution Approach 1:
The patent applies different properties to different regions of the phosphor wheel by using distinct phosphor materials (blue, green, yellow, red segments) at different angular positions, allowing each region to contribute its specific wavelength while maintaining overall spatial uniformity through proper segmentation and rotation control
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 adjustable color temperature, high white light output efficiency, and good spatial uniformity, simplifying the projection system and enabling the use of high power blue light sources while distributing heat effectively across the phosphor wheel.
Implementation Method 1
The light scattering material in some embodiments comprises light scattering particles disposed in the binder. The light scattering particles in some embodiments have size in a range of 0.1-50 microns.
Implementation Method 2
a phosphor wheel operates as a second light source and is stimulated by a blue laser diode to produce green, yellow, and red light
Data Source
AI summary
A white light source comprises a luminescent layer comprising a phosphor and light scattering material disposed in a binder, and a light source arranged to illuminate the luminescent layer with blue light. The white light source outputs white light comprising converted phosphor emission light from the phosphor illuminated by the blue light and unconverted scattered blue light that is scattered by the light scattering material. The unconverted scattered blue light has a spatial distribution matching a spatial distribution of the converted phosphor emission light. In some embodiments the spatial distributions are approximately Lambertian spatial distributions. The white light source may comprise a phosphor wheel including a disk-shaped substrate on which the luminescent layer is disposed as a phosphor ring. The phosphor ring may comprise the phosphor and light scattering material disposed in the binder with uniform composition around the annulus of the phosphor ring.