Light Guide Irradiation Member with Tapered Exit for Luminous Efficiency
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Solution Overview
Problem
Conventional light emitting devices using single or bundle optical fibers face issues where the irradiation range of excitation light becomes larger than the size of the light emitting section, leading to decreased luminous efficiency, especially as the number of excitation light sources increases.
Innovation Solution
A light emitting device with a light guide irradiation member that has a smaller cross-sectional area at the exit end compared to the entry end, guiding excitation light to prevent the irradiation range from exceeding the size of the light emitting section, utilizing a configuration such as an elliptic or circular truncated conic light converging section to efficiently converge excitation light onto a fluorescent substance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional optical fiber with identical cross-sectional areas at both ends is used, then the structure is simple and easy to manufacture, but the irradiation range of excitation light becomes larger than the light emitting section, decreasing luminous efficiency
Solution Approach 1:
The patent changes the geometric parameters of the optical fiber by making the cross-sectional area at the light exit section smaller than at the light incidence section. This parameter modification allows the irradiation range to be controlled and kept within the light emitting section boundaries, thereby improving luminous efficiency while maintaining manufacturing feasibility.
2Power
If multiple excitation light sources are bundled to generate high-power light, then the luminous flux increases, but the irradiation range becomes larger than the light emitting section, decreasing luminous efficiency
Solution Approach 1:
The patent applies parameter changes to the bundled optical fibers by reducing the cross-sectional area at the exit end relative to the incidence end. This allows multiple excitation light sources to be bundled for high luminous flux while controlling the irradiation range to match the light emitting section size, thereby maintaining high luminous efficiency.
3Loss of energy
If the cross-sectional area at the light exit section is made smaller than at the light incidence section, then the irradiation range is controlled within the light emitting section, improving luminous efficiency, but the manufacturing complexity increases
Solution Approach 1:
The patent implements parameter changes by creating an optical fiber with different cross-sectional areas at the incidence and exit sections. While this increases device complexity compared to uniform fibers, the complexity is justified by the significant improvement in luminous efficiency through controlled irradiation range.
Solution Approach 2:
The patent applies asymmetry by making the optical fiber structure non-uniform along its length, with the exit section having a smaller cross-sectional area than the incidence section. This asymmetric design enables precise control of light irradiation range to match the light emitting section, improving luminous efficiency despite increased manufacturing complexity.
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 maintains a controlled irradiation range, enhancing luminous efficiency and allowing for a more compact design with higher luminance and luminous flux, even with multiple excitation light sources, preventing the irradiation range from exceeding the light emitting section's size.
Implementation Method 1
the conventional optical fiber emits light which spreads to some extent with respect to a cross-sectional diameter of the conventional optical fiber since the conventional optical fiber guides excitation light while utilizing a total reflection of light
Implementation Method 2
a light emitting section from which light is emitted in response to the excitation light
Data Source
AI summary
A light emitting device of the present invention includes: a laser diode group which generates a plurality of laser beams; a cylindrical light emitting element which emits incoherent light in response to the plurality of laser beams; and a light guide irradiation section which (i) guides the plurality of laser beams entered via a light incidence plane toward a light irradiation plane and (ii) irradiates the light irradiation area of the cylindrical light emitting element with the plurality of laser beams thus guided. The light irradiation plane of the light guide irradiation section has an area which is smaller than that of the light incidence plane.