Light Source Device for Uniform Illumination via Optical Mixing
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Solution Overview
Problem
Conventional light-emitting sections excited with laser light suffer from color nonuniformity of illumination due to isotropic fluorescence emission and anisotropic directivity of unconverted laser light, leading to varying colors when viewed from different angles.
Innovation Solution
A light source device comprising an excitation light source, a light-emitting section that emits both excitation light and wavelength-converted light, and a light-mixing section, such as a diffusion plate, which mixes the excitation and wavelength-converted light to achieve uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If excitation light with high directivity is used to irradiate the light-emitting section, then irradiation efficiency is improved, but color uniformity of the illumination light deteriorates due to anisotropic emission
Solution Approach 1:
A light-mixing section is introduced as an intermediary component between the light-emitting section and the output. This section mixes the excitation light and wavelength-converted light that have different emission characteristics, thereby uniforming the color distribution while preserving the high directivity of the excitation light for efficient irradiation.
Solution Approach 2:
The illumination light is segmented into two distinct components: excitation light that maintains directivity for efficient irradiation, and wavelength-converted light that provides broad spectrum coverage. These segmented components are then recombined in the light-mixing section to achieve both high irradiation efficiency and color uniformity.
2Use of energy by moving object
If laser light with directivity is used as excitation light, then light delivery efficiency is improved, but color nonuniformity occurs due to mixed isotropic and anisotropic emission
Solution Approach 1:
The light-mixing section serves as a mediator that receives both the anisotropically emitted excitation light and isotropically emitted wavelength-converted light from the light-emitting section. By mixing these light components with different emission patterns, it achieves color uniformity while maintaining the efficiency benefits of directed laser excitation.
3Device complexity
If direct output of illumination light without mixing is used, then device complexity is reduced, but color uniformity deteriorates due to angular distribution bias
Solution Approach 1:
The illumination light is segmented into excitation light and wavelength-converted light components that are separately managed and then recombined in the light-mixing section. This segmentation approach achieves color uniformity while keeping the overall device structure relatively simple through the use of a single mixing section.
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 mixing of excitation and wavelength-converted light results in improved color uniformity of the illumination light, reducing variations when viewed from different angles.
Implementation Method 1
wavelength-converted light obtained by wavelength conversion of a portion of the excitation light
Implementation Method 2
a light-mixing section that mixes the excitation light and the wavelength-converted light
Data Source
AI summary
A headlight system in accordance with the present invention includes: a semiconductor laser element that emits laser light; a light-emitting section that upon receipt of the laser light emitted from the semiconductor laser element, emits illumination light which is both the laser light and fluorescence obtained by wavelength conversion of a portion of the laser light; and a diffusion plate that mixes the laser light and fluorescence which are contained in the illumination light emitted by the light-emitting section.