Composite Dichroic Mirror for Projector Light Source Efficiency
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Solution Overview
Problem
In optical systems using dichroic mirrors, there is a decrease in luminous efficiency due to overlapping and reflection of red and green wavelength bands, resulting in unused red light being discarded.
Innovation Solution
A light source device with a composite dichroic mirror having distinct areas to transmit blue and green wavelengths while reflecting red wavelengths, optimizing the use of red light by guiding it in a different direction than green and blue wavelengths, and using a reduction optical member to focus light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dichroic mirror is used to separate red and green wavelength bands, then color separation is achieved, but luminous efficiency decreases due to reflection of overlapping wavelengths
Solution Approach 1:
The optical wheel is divided into distinct functional areas: a fluorescent area for green light generation, a diffuse transmission area for blue light transmission, and a light blocking area. This segmentation allows each area to handle specific wavelength bands independently, preventing the wavelength overlap problem that occurs with traditional dichroic mirrors and enabling complete utilization of red light from the red light source.
Solution Approach 2:
The patent introduces a red light source as an intermediary component that directly provides red wavelength light to the optical system. This eliminates the need to rely on reflected red light from the dichroic mirror, thereby capturing all red light energy that would otherwise be lost due to the mirror's reflection of overlapping wavelengths.
2Device complexity
If a single dichroic mirror is used for wavelength separation, then optical path simplification is achieved, but light use efficiency decreases due to wavelength overlap
Solution Approach 1:
The optical wheel is segmented into multiple functional areas (fluorescent area, diffuse transmission area, light blocking area) that work together to achieve wavelength separation without the limitations of a single dichroic mirror. This segmented approach maintains relatively simple optical system structure while dramatically improving light use efficiency by preventing wavelength overlap issues.
Solution Approach 2:
The optical wheel serves multiple functions simultaneously: it acts as a fluorescent converter for green light, a diffuser for blue light, and a wavelength separator for red light. This multi-functionality allows the system to achieve comprehensive wavelength separation and maximize light utilization without requiring complex multi-component optical paths.
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
Improves the light use efficiency by ensuring all red light is utilized as source light, reducing interference and enhancing the projection of color images.
Implementation Method 1
an optical wheel device having a fluorescent area which emits fluorescent light of a green wavelength band if being irradiated with light of a blue wavelength band emitted as excitation light from an excitation light radiation device
Implementation Method 2
a dichroic mirror which transmits light of the blue wavelength band and light of the red wavelength band and reflects light of the green wavelength band
Data Source
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AI summary
A light source device includes a first light source, a second light source and a composite dichroic mirror. The first light source is configured to emit light of a first wavelength band. The second light source is configured to emit light of a second wavelength band which is different from the first wavelength band. The composite dichroic mirror has a first area and a second area which characteristics is different from characteristics of the first area. The composite dichroic mirror reflects the light of the first wavelength band while transmitting the light of the second wavelength band. The light of the first wavelength band is radiated corresponding to the first area and the second area of the composite dichroic mirror, and the light of the second wavelength band is radiated corresponding to the first area of the composite dichroic mirror.