Staggered Wavelength Conversion Wheels for Projection Light Stability
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Solution Overview
Problem
In digital light processing projection apparatuses, the boundary between regions of different colors on a rotating wheel can cause a 'spoke' effect when intersecting with the blue excitation beam, leading to significant reduction in output light, with up to 20% detriment in light output when beam output is suspended to prevent this issue.
Innovation Solution
The illumination system employs a first and second wavelength conversion device disposed on opposite surfaces of a rotating wheel, with each device having regions corresponding to each other, allowing the boundary of one device to intersect with the excitation beam at a different time than the boundary of the other device, thereby preventing simultaneous intersection and maintaining stable light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If beam output is suspended to prevent spoke effect, then spoke occurrence is prevented, but light output is reduced by up to 20%
Solution Approach 1:
The single rotating wheel with wavelength conversion regions is divided into two separate rotating wheels (first and second wavelength conversion devices), each with its own set of regions and boundaries. This segmentation allows the boundaries to be staggered in time, so when one boundary passes through the excitation beam path causing a spoke effect, the other wheel's regions are positioned differently, compensating for the light output and preventing the harmful spoke effect while maintaining overall light intensity.
2Object-affected harmful factors
If beam output is suspended to prevent spoke effect, then display quality is maintained, but output light is reduced
Solution Approach 1:
The illumination system combines the output of two wavelength conversion devices (first and second rotating wheels) to produce the final illumination beam. When one device experiences a boundary transition that would cause spoke effect, the other device simultaneously provides stable light output, and their combined output maintains consistent illumination intensity, thereby preventing spoke effect while preserving overall light quantity.
3Device complexity
If a single rotating wheel is used, then device complexity is low, but spoke effect occurs causing light output reduction
Solution Approach 1:
The single rotating wheel structure is segmented into two separate rotating wheels (first and second wavelength conversion devices), each with fewer regions. While this increases the number of components, each individual wheel becomes simpler to manufacture and the staggered boundary timing eliminates the spoke effect, resulting in net improvement in light output stability and quantity.
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 ensures that when one boundary intersects with the excitation beam, the other device compensates, maintaining stable illumination beam intensity and providing good display quality by preventing simultaneous suspension of light output.
Implementation Method 1
a blue excitation beam (blue laser beam) may act as the light source, beams of other colors may be produced through a rotating wheel (e.g., a wavelength conversion wheel or a color wheel)
Data Source
AI summary
An illumination system configured to provide an illumination beam is provided and includes a light-source module and a first and a second wavelength conversion devices. The light-source module provides a first and a second excitation beams. The first wavelength conversion device is disposed on a path of the first excitation beam and has first regions and at least one first boundary disposed between every two adjacent first regions. The second wavelength conversion device is disposed on a path of the second excitation beam and has second regions and at least one second boundary disposed between every two adjacent second regions. The second regions correspond to the first regions. A time point when the first boundary gets into the path of the first excitation beam is different from a time point when the second boundary gets into the path of the second excitation beam. A projection apparatus is also provided.