Solid State Light Sources for Digital Spokes in Color Wheel Systems
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Solution Overview
Problem
Current DLP and SSL-based projection systems using color wheels suffer from significant light losses due to 'undefined' light emitted during the transition areas between color segments, known as conventional spokes, which limits flexibility and efficiency across different application modes.
Innovation Solution
The system employs a DLP color wheel design with transparent segments for blue light and the ability to toggle primary light sources on and off rapidly, effectively canceling out conventional spokes and allowing for flexible duty cycle settings without changing the color wheel, thereby reducing light losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a color wheel with multiple color segments is used to generate sequential colors of light, then the illumination system can produce colored images for projection, but light losses occur during the transition areas (conventional spokes) between color segments
Solution Approach 1:
The patent changes the spectral parameters of the light source by using multiple solid state light sources with different spectral distributions (blue, green, red LEDs) instead of a single broadband source. This allows selective emission of primary colors during spoke times, transforming the harmful broadband spoke light into useful primary color light that can be utilized by the projection system.
Solution Approach 2:
The patent converts the harmful effect of spoke light (which causes color instability and light loss) into a beneficial resource by using solid state light sources to emit primary colors during the spoke time. The light that would otherwise be wasted during transitions is now used to illuminate the spatial light modulator, improving overall system efficiency.
2Stability of the object's composition
If the light source is switched off during spoke time to prevent color changes, then color stability is improved, but brightness of the illumination system is reduced
Solution Approach 1:
The patent employs periodic switching of solid state light sources synchronized with the color wheel rotation. During spoke times, specific solid state light sources are activated in a periodic manner to provide primary color light, while during color segment times, the broadband source is active. This periodic action maintains both color stability and continuous illumination.
Solution Approach 2:
The patent prepares primary color light from solid state sources in advance during the spoke time periods, so that when the color wheel transitions occur, the primary colors are already available to illuminate the spatial light modulator. This preliminary preparation ensures no interruption in useful light output.
3Loss of energy
If active compensation for spoke light is implemented to use light generated during spoke times, then light utilization is improved, but system complexity increases due to additional components like photodiode assemblies and processors
Solution Approach 1:
The patent replaces the complex mechanical and electronic compensation system (color wheel with physical segments, photodiode sensors, processor-based control) with a simpler solid state lighting approach. The solid state light sources are directly controlled to emit primary colors during spoke times without requiring sensing or complex processing, eliminating the need for photodiode assemblies and compensation algorithms.
4Manufacturing precision
If traditional color wheels with opaque segments are used, then color separation is achieved, but flexibility for different application modes (overlap and non-overlap) is limited
Solution Approach 1:
The patent creates a universal illumination system that can operate in multiple modes (overlap and non-overlap applications) using the same hardware configuration. The solid state light sources can be selectively activated to provide primary colors for both overlap modes (where color sequences overlap in time) and non-overlap modes (where colors are strictly sequential), eliminating the need for mode-specific hardware or complex mechanical adjustments.
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 light losses by ensuring that only primary light is provided during spoke times, enhancing the flexibility and efficiency of the system across various application modes, including non-overlap and overlap applications.
Implementation Method 1
The first light source comprises a solid state light source and the second light source comprises a solid state light source. The at least two solid state light sources are used to directly or indirectly generate at least two primary color light of different color
Implementation Method 2
a phosphor which generates a fluorescence including the two colors other than the color of the light emitted from the light source section
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3A~3B
AI summary
The invention provides a system (1000) for processing light, the system (1000) configured to provide along a main beam path (1105) a beam (1005) of system light (1001), wherein the system light (1001) comprises one or more of first light (111) having a first spectral distribution, second light (121) having a second spectral distribution, and third light (131) having a third spectral distribution, wherein the first, second, and third spectral distributions mutually differ, wherein the system (1000) comprises: - a lighting arrangement (100) configured to provide along a first beam path (1101) a first beam (101) comprising primary light (103) having a spectral power distribution with at least 80% of the spectral power consisting of one of the first light (111), the second light (121), and the third light (131), and/or configured to provide along a second beam pat (1102) a second beam (102) comprising composed light (104) having a spectral distribution with at least 80% of the spectral power consisting of the two others of the first light (111), the second light (121), and the third light (131); - an optical filter system (200) comprising a plurality of segments (210), wherein two or more segments (210) have different transmission characteristics for one or more of the primary light (103) and the composed light (104); wherein during operation of the system (1000) the optical filter system (200) is configured to have the segments (210) of the plurality of segments (210) sequentially intercept the main beam path (1105) or the second beam path (1102), wherein during a time period (tsp) the beam path (1105, 1102) is partially intercepted by a first segment (211) and partially intercepted by a second segment (212); - a control system (300) configured to control the lighting arrangement (100) and the optical filter system (200) such that during at least part of the time period (tsp) at least 80% of a spectral power distribution of the system light (1001) of the beam (1005) of system light (1001) consists of the primary light (103).