Phosphor Wheel Filter Segments for Laser Projector Color Accuracy
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Solution Overview
Problem
Current solid state illuminated projectors using blue laser diodes and phosphor wheels face challenges in achieving desired color points and bandwidths due to unwanted blue laser light interference and variability in color generation, leading to aesthetically displeasing results and difficulties in correcting pixel intensities.
Innovation Solution
Incorporating a second filter wheel or filter segments on the phosphor wheel to coordinate with phosphor segments for filtering light, allowing for specific wavelength selection and diffusion to achieve desired color wavelengths, thereby correcting unwanted blue laser light interference and enhancing color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If blue laser light is used to directly illuminate the phosphor wheel, then blue color light is generated, but unwanted blue laser light interference occurs and color accuracy deteriorates
Solution Approach 1:
The patent extracts the harmful blue laser light from the illumination path by introducing a filter that selectively blocks blue wavelengths while transmitting other colors. The filter removes the unwanted blue component that causes color accuracy deterioration, allowing the system to maintain high illumination intensity from the laser while eliminating the harmful interference.
Solution Approach 2:
The patent introduces a filter as an intermediary element between the blue laser light source and the phosphor wheel. This filter acts as a mediator that selectively transmits certain wavelengths while blocking others, specifically allowing the desired color wavelengths to pass through while preventing the harmful blue laser light from reaching the projection path.
2Adaptability or versatility
If phosphor segments are used to generate different colors, then color sequence illumination is achieved, but bandwidth is too broad and color precision deteriorates
Solution Approach 1:
The patent applies local quality by introducing wavelength-selective filters for each color channel in the phosphor wheel system. Each filter is specifically designed to transmit only the desired wavelength range for its corresponding color while blocking other wavelengths. This localized wavelength control at each color segment maintains the versatility of color sequence generation while achieving precise bandwidth control for accurate color reproduction.
3Device complexity
If a single filter wheel is used, then device complexity is reduced, but filtering precision and color accuracy deteriorate
Solution Approach 1:
The patent segments the filtering function by dividing the single filter wheel into multiple independent filter wheels, each dedicated to specific wavelength ranges or color channels. This segmentation allows each filter wheel to be optimized for its specific function, achieving high wavelength selection accuracy while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The patent transitions from a single-dimension filter wheel approach to a multi-dimensional filtering system with multiple wheels operating in sequence. This dimensional expansion allows for more precise wavelength selection by combining the filtering effects of multiple wheels, each handling specific spectral regions, thereby achieving superior color accuracy without excessive complexity.
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 enables the generation of desired color wavelengths with narrower bandwidths, improving color accuracy and consistency in projected images by filtering phosphor-emitted light and reducing speckle, thus enhancing the overall image quality.
Implementation Method 1
Incorporating a second filter wheel or filter segments on the phosphor wheel to coordinate with phosphor segments for filtering light, allowing for specific wavelength selection
Implementation Method 2
a green color light is generated indirectly by illuminating a green color-emitting segment of the spinning phosphor wheel with light from a typically blue laser light emitting diode (LED), while red color light is generated either indirectly by illuminating a red color-emitting phosphor segment
Implementation Method 3
The blue color light is usually generated directly using the blue laser light itself. A diffuser is typically used to reduce speckle from the coherent light.
Data Source
AI summary
An illuminator for an imaging system using a spatial light modulator has first color laser light directed by a dichroic element to a first annular band on a rotatable member. The first band includes phosphor segments that respond to illumination by the first color light to emit second and third color light along a first path back to the dichroic element for output, and a light transmitting or reflecting segment that transmits or reflects the first color along the same or a second path back to the dichroic element for output. The output light is directed to a second annular band on the same or a different rotatable member. The second band includes filter segments corresponded to respectively selectively filter output light generated by the first band segments.