Optical System Wavelength Conversion for Light Recycling
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Solution Overview
Problem
Current projection systems, particularly those using digital micro-mirror devices, suffer from low light efficiency due to the sequential color display method of color wheels, where unneeded colors are reflected back as heat, leading to significant light energy loss.
Innovation Solution
The optical system incorporates a wavelength conversion unit to convert light reflected by filtering units and a reflection unit to recycle this light back to the filtering units, enhancing light efficiency by re-utilizing the otherwise lost light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a color wheel with sequential color filtering is used in a projection system, then the system can display full color images using a digital micro-mirror device, but a significant portion of light energy is lost when unneeded colors are reflected back as heat
Solution Approach 1:
The patent recovers light that would otherwise be discarded by the color wheel. The reflection unit captures light reflected from the color wheel, and the wavelength conversion unit converts this reflected light into useful wavelengths that can be reused by the projection system, thereby recovering energy that would have been lost.
Solution Approach 2:
The patent converts the harmful reflected light (which causes energy loss and heat generation) into a beneficial resource. By using the wavelength conversion unit to convert the reflected light into useful wavelengths, the system transforms what was previously waste energy into useful illumination, improving overall light efficiency.
2Illumination intensity
If a high power light source is used to compensate for light loss in the projection system, then the brightness can be maintained, but the light source lifespan is reduced and energy consumption increases
Solution Approach 1:
Instead of discarding the reflected light from the color wheel, the system recovers it through the reflection unit and wavelength conversion unit. This recovery process reduces the need for additional high-power light sources, thereby extending light source lifespan and reducing energy consumption while maintaining image brightness.
Solution Approach 2:
The patent creates a continuous light recycling pathway where reflected light is continuously converted and fed back into the optical system. This continuous recovery and reuse of light energy maintains brightness levels without requiring increased power input, thus preserving light source duration and reducing energy consumption.
3Power
If a high pressure mercury lamp is used as the light source, then sufficient total lumens can be generated, but the spectral distribution does not match the filtering characteristics of the color wheel, resulting in inefficient light utilization
Solution Approach 1:
The patent changes the wavelength parameter of the reflected light through the wavelength conversion unit. By converting reflected light into specific wavelengths that match the color wheel's transmission characteristics, the system optimizes the spectral distribution to better match the filtering characteristics, thereby improving light emission efficiency while maintaining total lumens output.
Solution Approach 2:
The patent converts the mismatched spectral distribution (which causes inefficiency) into a beneficial alignment. The wavelength conversion unit transforms reflected light into wavelengths that perfectly match the color wheel's transmission bands, turning what was previously wasted energy into efficiently utilized light, thereby improving overall energy use without sacrificing total output.
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 improves light efficiency by recycling and re-utilizing light that would otherwise be lost, enhancing the intensity of specific color components like red, green, and blue, thereby improving the color render index and overall brightness of the image frame.
Implementation Method 1
a wavelength conversion unit (260a) disposed on an inner wall of the reflection sleeve to convert a part of the illumination beam (214a) reflected by the filtering units (222, 224, 226) into a converted beam (216a) having a wavelength different from that of the reflected light
Implementation Method 2
a multi-layer optical coating layer (270) disposed on the filtering units and located between the wavelength conversion unit and the filtering units, so that a part of the converted beam from the wavelength conversion unit and a part of the illumination beam reflected by the filtering units and not converted by the wavelength conversion unit are reflected to the wavelength conversion unit
Data Source
Figure 1A~1B
Figure 2~4
Figure 5
AI summary
An optical system including a light source, a filtering module, a wavelength conversion unit, and a reflection unit is provided. The light source emits an illumination beam. The filtering module is disposed on a transmission path of the illumination beam and includes a plurality of filtering units having different colors. The filtering units move into the transmission path of the illumination beam in turn. Each filtering unit reflects a part of the illumination beam and allows another part of the illumination beam to pass through. The wavelength conversion unit is disposed on a transmission path of the part of the illumination beam reflected by at least one of the filtering units to convert the part of the illumination beam reflected by the at least one of the filtering units into a converted beam. The wavelength conversion unit is disposed on the reflection unit.