Illumination System Stabilizing Optical Path via Polarization Splitting
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Solution Overview
Problem
The existing projection apparatuses face issues with unstable optical paths and reduced light use efficiency due to the wobbling of phosphor wheels and non-uniform light output caused by excitation beams entering light homogenizing elements at small angles.
Innovation Solution
An illumination system with an excitation light source module, a light splitting and combining module, a filter module, and a wavelength conversion module, where the excitation light source module provides two excitation beams with different polarization states or wavelengths, allowing them to pass through distinct areas of the filter module and eliminating the need for transmission through the wavelength conversion module, thereby stabilizing the beam path and enhancing light uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor wheel with embedded blue light reflection mirror is used to generate color light beams, then color purity is improved, but the phosphor wheel is likely to wobble when rotating, resulting in an unstable optical path and reduced light use efficiency
Solution Approach 1:
The patent divides the excitation beam into multiple beams with different polarization states using a beam splitting element. Each polarized beam is then directed to a separate wavelength conversion element (first and second wavelength conversion elements) that are spatially segmented. This segmentation eliminates the need for a rotating phosphor wheel, thereby stabilizing the optical path while maintaining color purity through the separated wavelength conversion paths.
2Device complexity
If the excitation beam enters the light homogenizing element at a small angle, then the optical path is simplified, but the uniformity of the overall light output is reduced
Solution Approach 1:
The patent applies different optical path configurations to different polarized beams. The first polarized beam is directed through a first optical path with specific angle of incidence, while the second polarized beam follows a second optical path with different angular characteristics. This local differentiation in optical path design allows each beam to be optimized for uniformity while maintaining overall system simplicity.
3Device complexity
If a single excitation beam is used to excite the phosphor wheel, then the device structure is simplified, but the light use efficiency is reduced due to the need for wavelength conversion
Solution Approach 1:
The patent merges the functions of multiple wavelength conversion elements into a single integrated illumination system. The first and second wavelength conversion elements, along with their respective optical paths, are combined to produce a unified illumination beam that maintains high light use efficiency. This merging approach achieves efficient light utilization without requiring overly complex device structures.
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 configuration improves the stability of the beam transmission path and increases light use efficiency by eliminating the need for wavelength conversion, resulting in a more uniform illumination beam and better performance in projection apparatuses.
Implementation Method 1
The filter module has a light passing area configured to allow the excitation beam to pass there-through and at least one light filtering area configured to reflect the excitation beam
Implementation Method 2
the filter module has a light passage region through which the excitation beam passes and at least one of reflecting the excitation beam filter area
Implementation Method 3
The wavelength conversion module is disposed on the transmission path of the excitation beam reflected by the at least one light filtering area and is configured to convert the excitation beam reflected by the at least one light filtering area into a conversion beam
Implementation Method 4
The at least one excitation beam from the light splitting and combining module includes a first excitation beam and a second excitation beam which are different from each other in polarization state or wavelength range
Data Source
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AI summary
An illumination system includes an excitation light source module, a light splitting and combining module, a filter module, and a wavelength conversion module. The excitation light source module provides an excitation beam. The light splitting and combining module is disposed on a transmission path of the excitation beam. The excitation beam includes a first and a second excitation beam which are different from each other in polarization state or wavelength range. The filter module is disposed on the transmission path of the excitation beam. The filter module includes a light passing area configured to allow the excitation beam to pass there-through and a light filtering area. The wavelength conversion module is disposed on the transmission path of the excitation beam reflected by the light filtering area and configured to convert the reflected excitation beam into a conversion beam. A projection apparatus including the above illumination system is also provided.