Rotating Wavelength Conversion Element for Thermal Management
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Solution Overview
Problem
Current illumination systems for digital projection face challenges in achieving high brightness and long-term stability due to thermal degradation of wavelength conversion materials, particularly phosphors, which lead to color point degradation and reduced efficiency.
Innovation Solution
An illumination device with a wavelength conversion element that moves relative to the excitation light source in a progressive, two-dimensional pattern, distributing the power density and reducing thermal stress, combined with cooling mechanisms and modulation of light source power to extend the lifespan of the materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the excitation light is concentrated in a small spot on the phosphor layer, then the light capture efficiency is improved, but the energy density increases causing phosphor saturation and damage
Solution Approach 1:
The patent applies rotational movement to the phosphor layer (color wheel) to dynamically distribute the stationary excitation light spot across different phosphor regions over time. This dynamic approach allows continuous operation at high power density while preventing localized saturation and thermal damage, resolving the contradiction between light capture efficiency and phosphor layer stability.
2Device complexity
If the phosphor layer is stationary, then the system structure is simple, but the phosphor degrades quickly due to concentrated thermal stress
Solution Approach 1:
The patent introduces rotational movement of the phosphor layer to distribute thermal stress over time and space, significantly extending phosphor lifespan. The relatively simple implementation (rotating the color wheel) adds minimal structural complexity while dramatically improving durability, making this principle highly effective for resolving this contradiction.
3Device complexity
If air cooling is used for the rotating color wheel, then the cooling structure is simple, but the cooling efficiency is insufficient for high power applications
Solution Approach 1:
The patent transitions from air cooling to liquid cooling for the color wheel to dramatically improve heat dissipation efficiency. Liquid cooling provides superior thermal management for high power applications while maintaining reasonable structural complexity, effectively resolving the contradiction between cooling structure simplicity and phosphor temperature 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 significantly reduces long-term and short-term degradation of the wavelength conversion materials, enhancing the stability and efficiency of the illumination system while maintaining consistent light output and color accuracy.
Implementation Method 1
a wavelength conversion element (21) comprising: a region with a wavelength conversion material capable of absorbing the excitation light of said light source and emitting light having wavelengths different from that of the excitation light
Implementation Method 2
the wheel surface itself and the phosphor layer are cooled by air
Implementation Method 3
which provides a better basis for transporting the dissipated heath through the color wheel's metal base
Data Source
AI summary
A method and apparatus is described for producing high brightness, e.g. multicolor light, whereby a region of a wavelength conversion element and a light source producing excitation light are moved relative to each other so that said region is exposed to the excitation light at different times and in a progressive movement that scans across a part of the entire surface of the wavelength conversion element. The wavelength conversion element can be cooled by air or with a liquid.