Dichroic Mirror Light Source for Laser Phosphor Projectors
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Solution Overview
Problem
The existing projection systems using laser phosphor technology face challenges with red phosphor saturation and decreased color purity under increased excitation power, requiring the use of filters to obtain red light, which increases system volume and complexity.
Innovation Solution
A light source system without a filter wheel, utilizing a phosphor wheel with alternating red, green, and blue regions that alternately insert into the light path, allowing for improved color purity and brightness through the use of red and green phosphors, and optionally adding red or green laser light to enhance performance under varying power conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If red phosphor is used to generate red light through laser excitation, then the system structure is simplified, but color purity decreases due to saturation phenomenon at high power
Solution Approach 1:
The patent extracts the problematic red phosphor material and replaces it with a dichroic mirror that reflects red light from the blue laser directly. This removes the saturation issue while maintaining system simplicity. The dichroic mirror selectively reflects red wavelengths while transmitting other wavelengths, achieving high color purity without phosphor conversion losses.
Solution Approach 2:
The patent changes the optical path parameters by introducing a dichroic mirror with specific wavelength selectivity. Instead of relying on phosphor emission spectra, the system uses reflective optics to separate red light, fundamentally changing how red light is generated and maintaining purity across varying laser powers.
2Manufacturing precision
If a filter wheel is added to obtain red light from yellow fluorescence, then color purity is improved, but system volume and complexity increase
Solution Approach 1:
The patent merges the red light generation function into the existing optical path by using a dichroic mirror that simultaneously serves as a beam splitter and a color separator. This eliminates the need for a separate filter wheel while maintaining color purity, as the dichroic mirror integrates multiple optical functions into a single component.
Solution Approach 2:
The dichroic mirror performs multiple functions: it reflects red light to the projection path, transmits blue and green wavelengths to the phosphor wheel, and acts as a beam splitter. This multi-functionality replaces the specialized filter wheel, reducing system complexity while maintaining color separation efficiency.
3Manufacturing precision
If a filter wheel is added to obtain red light from yellow fluorescence, then color purity is improved, but system volume increases
Solution Approach 1:
The patent removes the bulky filter wheel assembly from the system and replaces it with a thin dichroic mirror coating on an existing optical element. This extraction of the problematic component dramatically reduces system volume while maintaining the ability to separate red light with high purity.
Solution Approach 2:
The dichroic mirror is implemented as a thin film coating on an optical element, replacing the mechanical filter wheel structure. This thin-film approach maintains color separation functionality while occupying minimal space, enabling compact projector designs without sacrificing optical performance.
4Manufacturing precision
If synchronous control between color wheel and filter wheel is implemented, then color accuracy is improved, but control complexity increases
Solution Approach 1:
The patent removes the filter wheel from the system, thereby eliminating the need for synchronous control mechanisms. The dichroic mirror provides passive, continuous color separation without requiring coordination with rotating components, simplifying the control system while maintaining color accuracy through optical rather than mechanical means.
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 solution achieves better color purity and brightness consistency, reduces system volume, and eliminates the need for synchronous control, resulting in a more compact, ultra-thin, and reliable light source system.
Implementation Method 1
the laser beam is converged to a surface of the color wheel 104 through the collection lens 103 and excites the phosphor on the color wheel 104 to generate excited light
Data Source
AI summary
The light source system includes a first light source, a light splitting device, a wavelength conversion device, and a light guiding device. The first light source emits first light. The wavelength conversion device includes at least a first color light region and a second color light region, which are sequentially inserted into an outgoing path of the first light. The first color light region emits second light excited by the first light to the light splitting device. The second color light region reflects the first light to the light splitting device. The light splitting device directs one of the first light and the second light to a light path and directs the other to the light guiding device. The first light or the second light is reflected by the light guiding device to the light splitting device, and then is guided to the light path by the light splitting device.