Wavelength-Converting Wheel Illumination System for Adjustable Color Proportion
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Solution Overview
Problem
Current projection apparatus using blue laser diodes for illumination face challenges in achieving compact size and cost-effectiveness due to the need for additional optical paths and fixed color timing, which limits adjustable color proportion and increases system volume and complexity.
Innovation Solution
An illumination system with a wavelength-converting wheel and a control unit that adjusts the proportion and position of light converting regions to generate different colors by switching between first and second exciting light sources, allowing for adjustable color proportion in the emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blue laser diode is used to excite phosphor powder on a phosphor wheel to generate yellow light and green light, then the cost is reduced compared to using high-brightness red and green laser diodes, but the system requires additional optical path loops and fixed color timing which increases system volume and complexity
Solution Approach 1:
The phosphor wheel is divided into multiple irradiation portions with different light converting regions (yellow, green, red phosphors) that can be selectively excited by the blue laser beam. This segmentation allows different color lights to be generated in different time periods without requiring separate optical paths for each color, thereby reducing system complexity while maintaining cost effectiveness
Solution Approach 2:
The blue laser diode is driven to emit light in periodic pulses that correspond to the rotation of the phosphor wheel. By synchronizing the laser emission timing with the rotation position, different phosphor regions are excited at different periods to generate the required red, green and blue lights sequentially, eliminating the need for continuous multi-path optical systems
2Device complexity
If the timing of color light is fixed when designing the phosphor wheel and filter wheel, then the system structure is simplified, but the illumination system cannot adjust the proportion of color mixing in subsequent use
Solution Approach 1:
The control unit dynamically adjusts the driving parameters of the blue laser diode (emission timing, pulse width, intensity) based on the rotation position of the phosphor wheel. This dynamic control enables flexible adjustment of color mixing proportions and brightness ratios without requiring physical changes to the phosphor wheel structure, achieving both structural simplicity and operational adaptability
Solution Approach 2:
The system changes operational parameters (laser emission timing, duty cycle, intensity) rather than physical parameters (phosphor composition, wheel structure) to achieve color adjustment. This allows the fixed phosphor wheel design to produce variable color outputs by modifying when and how the blue laser excites different phosphor regions, maintaining structural simplicity while providing full color adaptability
3Ease of manufacture
If additional optical path loops are added to the system, then the required color lights can be generated, but the system volume increases and becomes less compact
Solution Approach 1:
The phosphor wheel integrates multiple light converting regions (yellow, green, red phosphors) into a single rotating component that is excited by a single blue laser beam. This merging of multiple color generation functions into one optical path eliminates the need for separate optical loops for each color, significantly reducing system volume while maintaining the capability to generate all required colors
Solution Approach 2:
The single blue laser diode serves multiple functions by exciting different phosphor regions at different times to generate blue light (direct transmission), green light (via yellow phosphor conversion), and red light (via red phosphor conversion). This multi-functionality eliminates the need for multiple dedicated light sources and optical paths, achieving compact system design
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
The solution enables adjustable color proportion and reduced system volume and optical components, enhancing the flexibility and efficiency of the projection apparatus in generating desired colors.
Implementation Method 1
The first light converting region is for converting the first exciting beam into a first converted beam and reflecting the first converted beam. The second light converting region is for converting the second exciting beam into a second converted beam and reflecting the second converted beam.
Implementation Method 2
The first light reflecting region is for reflecting the first exciting beam. The second light reflecting region is for reflecting the second exciting beam.
Data Source
AI summary
An illumination system includes a first exciting light source, a second exciting light source and a wavelength-converting wheel. The first exciting light source provides a first exciting beam. The second exciting light source provides a second exciting beam. The wavelength-converting wheel is disposed on a transmission path of the first exciting beam and the second exciting beam. The wavelength-converting wheel has a first annular irradiation portion and a second annular irradiation portion. The first annular irradiation portion has a first light reflecting region and a first light converting region. The second annular irradiation portion has a second light reflecting region and a second light converting region. The invention further provides a control unit and a projection apparatus. The invention can adjust the color proportion of the illumination beam projected by the illumination system, and reduce the volume of the illumination system and the number of optical components.