Parallel Phosphor Rod Light Source for Compact Projectors
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Solution Overview
Problem
Conventional light source devices for projectors face challenges in achieving high luminance while maintaining a compact size, as increasing the size of the wavelength conversion member leads to increased etendue, reducing light use efficiency.
Innovation Solution
The use of a light source device comprising two parallel rod parts with phosphors, where excitation light enters from the side surfaces and is converted to fluorescence, which is then emitted from a smaller end surface, utilizing reflecting films and an angle conversion element to improve light path folding and collimation, thereby reducing the device's size and etendue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the size of the wavelength conversion member is increased to achieve high luminance, then the luminance is improved, but the etendue increases and light use efficiency decreases
Solution Approach 1:
The patent divides the wavelength conversion member into multiple phosphor rods arranged in parallel. Each rod has a large side surface area for excitation light entry and a small end surface area for fluorescence emission. This segmentation allows multiple rods to collectively provide high luminance while each rod maintains a small light exit area, thus keeping the overall etendue small and improving light use efficiency.
2Illumination intensity
If the size of the wavelength conversion member is increased to achieve high luminance, then the luminance is improved, but the device size increases
Solution Approach 1:
The patent utilizes the lateral arrangement of multiple phosphor rods in parallel, extending the light-generating capability in the horizontal dimension rather than increasing the vertical length. Each rod has a large side surface area perpendicular to the excitation light direction, allowing efficient light conversion without increasing the overall device length in the optical path direction.
3Illumination intensity
If the area of the light exit surface is increased, then the luminance is improved, but the etendue increases and light use efficiency decreases
Solution Approach 1:
The patent merges the light emission function of multiple phosphor rods into a single optical path. Although there are multiple rods with small individual light exit areas, their fluorescence emissions are combined through optical elements (lenses or reflectors) to form a unified high-luminance beam. This merging achieves high apparent luminance without increasing the physical light exit surface area of individual components, thus maintaining small etendue.
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 configuration enhances light use efficiency and reduces the size of the light source device, improving luminance and minimizing etendue compared to traditional designs, while allowing for a more compact projector setup.
Implementation Method 1
a first rod part (51) including a phosphor and having a light exit surface (51a), and a second rod part (52) including a phosphor, wherein excitation light enters side surfaces (51c, 52c) of the phosphor rod (50) and is converted to fluorescence, and the fluorescence is emitted from the light exit surface (51a)
Implementation Method 2
a first reflecting film (55f1) disposed so as to be opposed to a tilted surface (51d) formed in an end part of the first rod part (51), and a second reflecting film (55f2) disposed so as to be opposed to a tilted surface (52d) formed in an end part of the second rod part (52)
Data Source
AI summary
A light source device according to the present disclosure includes a light source configured to emit excitation light, a first rod part including a phosphor and configured to emit fluorescence in response to incidence of the excitation light, a second rod part located in parallel to the first rod part, including a phosphor, and configured to emit fluorescence in response to incidence of the excitation light, a first reflecting film disposed so as to be opposed to a tilted surface formed in an end part of the first rod part, and a second reflecting film disposed so as to be opposed to a tilted surface formed in an end part of the second rod part.