Bidirectional Wavelength Conversion for Thin Vehicle Lighting
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Solution Overview
Problem
Conventional vehicle light fittings with semiconductor light emitting elements face challenges in reducing thickness due to acute incident angles of reflected light, leading to increased dimensions, and wavelength conversion members in light emitting devices experience degradation and efficiency reduction due to high temperature from high-powered excitation light sources.
Innovation Solution
A light emitting device with a bidirectional light distribution from the peripheral end surface of a wavelength conversion member, utilizing light blocking and reflection means to reduce vehicle light fitting thickness and prevent glare, while also employing a ring-shaped wavelength conversion member with a light deflection means to reduce temperature and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional semiconductor light emitting element with Lambertian radiation pattern is used, then light can be emitted in all directions, but the vertical thickness of the vehicle light fitting increases due to the need for large projection lens dimensions
Solution Approach 1:
The invention segments the radiation pattern into two distinct directions: forward direction (toward the projection lens) and backward direction (away from the projection lens). This is achieved through the bidirectional light distribution characteristic of the wavelength conversion member, which directs light preferentially in these two opposite directions rather than uniformly in all directions like conventional Lambertian sources.
Solution Approach 2:
The invention changes the light distribution from a three-dimensional omnidirectional pattern to a two-dimensional bidirectional pattern concentrated in specific directions. By concentrating light emission into two primary directions (forward and backward), the optical system can achieve the required illumination with a more compact vertical arrangement, reducing the thickness of the vehicle light fitting.
2Illumination intensity
If high-powered excitation light sources are used to increase light output, then illumination intensity improves, but the wavelength conversion member experiences temperature-related degradation and efficiency reduction
Solution Approach 1:
The invention extracts and removes the harmful thermal effects from the wavelength conversion member by introducing a heat dissipation structure. This structure specifically targets and removes excess heat generated during wavelength conversion, preventing temperature-related degradation while preserving the beneficial high light output from the high-powered excitation light source.
Solution Approach 2:
The heat dissipation structure acts as an intermediary between the wavelength conversion member and the surrounding environment. It mediates the thermal energy transfer, conducting heat away from the wavelength conversion member and dissipating it safely, thereby protecting the conversion member from thermal damage while allowing high-powered operation.
3Area of stationary object
If light is reflected in all directions to achieve uniform illumination, then coverage area increases, but glare is generated that affects visibility
Solution Approach 1:
The invention applies local quality control by directing light preferentially in specific directions (forward and backward) rather than uniformly in all directions. The bidirectional light distribution creates areas of high illumination intensity in desired directions while minimizing light emission in directions that would cause glare, thus achieving localized optimization of light distribution quality.
Solution Approach 2:
The invention converts the potential harmful effect of omnidirectional light scattering into a beneficial bidirectional light distribution pattern. By controlling the light distribution to concentrate emission in two primary directions, the system eliminates glare-causing scattered light while maintaining adequate coverage area, effectively transforming a harmful radiation pattern into a beneficial one.
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 effectively reduces the vertical thickness of vehicle light fittings and suppresses temperature-related degradation of wavelength conversion members, maintaining efficiency even with high-powered excitation light sources, thereby improving light distribution patterns and extending component lifespan.
Implementation Method 1
a wavelength conversion member 13 that absorbs the excitation light to convert the wavelength and to emit light in a predetermined wavelength region
Implementation Method 2
a first light blocking means 15 arranged around a lower surface 13b of the wavelength conversion member 13
Implementation Method 3
When the first light blocking means is first reflection means, extraction efficiency of light can be improved by the operation of the first reflection means
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
Provided is a light emitting device used in a vehicle light fitting, the light emitting device including: an excitation light source that generates excitation light; a wavelength conversion member that absorbs the excitation light and that converts a wavelength to emit light in a predetermined wavelength region; and a first optical system that directs the excitation light from the excitation light source to the wavelength conversion member, wherein the wavelength conversion member includes at least a first surface, a second surface facing the first surface, and a peripheral end surface arranged between the first surface and the second surface, the first optical system is configured to direct the excitation light from the excitation light source to the first surface, and at least part of the second surface is covered by first light blocking means.