Light Source Unit with Segmented Luminescent Plate for Projector Red Luminance
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Solution Overview
Problem
Conventional data projectors using high-intensity discharge lamps face issues with insufficient red luminance due to lower luminous efficiency of red luminescent materials in light source units, leading to reduced screen luminance.
Innovation Solution
A light source unit comprising a luminescent plate with a luminescent material of high luminous efficiency, a monochromatic light source for a wavelength band corresponding to the low-efficiency material, and a light guiding system that differs the light shining positions of the first and second light sources on the luminescent plate, allowing for enhanced luminance by emitting light of multiple wavelength bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If luminescent material layers are disposed substantially equally in area on the luminescent wheel, then the structure is simple and uniform, but the luminance of red becomes insufficient due to lower luminous efficiency of red luminescent material
Solution Approach 1:
The patent applies local quality by making the area of the red luminescent material layer larger than that of green and blue luminescent material layers. Specifically, the red luminescent material layer has an area that is 1.2 to 2.0 times (preferably 1.5 to 2.0 times) that of the green and blue layers, compensating for its lower luminous efficiency and achieving balanced color output.
2Illumination intensity
If a single light source is used to excite all luminescent materials, then the device structure is simple, but the luminance efficiency is reduced due to the low efficiency of red luminescent material
Solution Approach 1:
The patent segments the light source into two independent sources: a first light source (ultraviolet or blue) that excites the luminescent materials, and a second light source (red) that directly emits red light. This segmentation allows the system to bypass the inefficient red luminescent material and directly provide high-luminance red light, thereby increasing overall screen luminance.
Solution Approach 2:
The luminescent wheel is designed with multi-functionality: it serves both as a color separation element (through the luminescent materials) and as a light guiding element (through the transparent base). The transparent base guides ultraviolet and blue light from the first light source to the luminescent material layers, while also allowing red light from the second light source to pass through to the projection optical system.
3Illumination intensity
If luminescent material layers are made larger in area to compensate for low efficiency, then red luminance improves, but the device size increases
Solution Approach 1:
The patent optimizes the area ratio parameters of the luminescent material layers. The red luminescent material layer area is set to be 1.2 to 2.0 times (preferably 1.5 to 2.0 times) that of the green and blue layers, rather than making it uniformly large. This parameter optimization achieves sufficient red luminance while minimizing the overall luminescent wheel size.
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 increases screen luminance by effectively utilizing high-efficiency luminescent materials and complementary light sources, improving color reproduction and projector performance.
Implementation Method 1
a luminescent plate having a luminescent light emission portion on which is formed a layer of a luminescent material which receives excitation light to emit luminous light
Implementation Method 2
a diffuse transmission portion which transmits light in a diffusing fashion
Data Source
AI summary
There is provided a light source unit comprising a luminescent plate having a luminescent light emission portion and a diffuse transmission portion, a first light source which emits light of a wavelength band which can excite the luminescent material, a second light source which emits light of a wavelength band which differs from the luminous light and the light emitted from the first light source, a light guiding optical system which guides light of respective wavelength bands in color emitted from the luminescent plate to a predetermined plane, and a light source control part for controlling individually the emission of light from the first light source and the second light source, wherein the luminescent plate is disposed on optical paths of the first light source and the second light source, wherein a light shining position of light from the first light source and a light shining position of light from the second light source are made to differ from each other on the luminescent plate, and wherein the light source control part controls so that the first light source and the second light source emit light simultaneously or separately to thereby emit synthesized light or monochromatic light.