Light Guide Asymmetry for Luminescent Light Extraction
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Solution Overview
Problem
Existing light emitting devices with luminescent concentrators suffer from low efficiency due to light escaping from surfaces other than the exit surface, and lack the ability to recycle light for polarization or collimation.
Innovation Solution
A light emitting device with a light guide having at least three side light input surfaces and a light exit surface, where the exit surface's circumference is more than four times larger than the side input surfaces' height, and the side input surfaces' area is less than four times the exit surface area, allowing for light recycling and increased intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light sources are arranged at surfaces of the waveguide, then the device structure is simplified, but light escapes from surfaces other than the exit surface, reducing efficiency
Solution Approach 1:
The patent applies asymmetry by configuring the light guide with specific geometric relationships: the exit surface has an area that is at least 10% of the total surface area of the light guide, and the distance from the exit surface to light sources is at least 50% of the distance from other surfaces to light sources. This asymmetric arrangement ensures that light preferentially exits through the designated exit surface while maintaining structural simplicity.
2Illumination intensity
If the exit surface area is increased, then more light can be extracted, but the side input surfaces area increases proportionally, reducing the intensity gain
Solution Approach 1:
The patent employs parameter changes by establishing specific quantitative relationships: the exit surface area is constrained to be at least 10% of the total surface area, and the distance from the exit surface to light sources is at least 50% of the distance from other surfaces. These parameter constraints optimize the balance between light extraction amount and intensity gain without requiring proportional increases in all surface areas.
3Ease of manufacture
If light is allowed to escape from all surfaces, then the device is simpler to manufacture, but the brightness at the exit surface is reduced
Solution Approach 1:
The patent applies local quality by creating different optical conditions at different locations: the exit surface is specifically designed with an area of at least 10% of the total surface area and is positioned at a specific distance from light sources (at least 50% of the distance from other surfaces). This localized optimization ensures that the exit surface has superior light extraction properties compared to other surfaces, achieving high brightness without complex manufacturing.
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 significantly increases the amount of light extracted from the exit surface, enhancing brightness and efficiency by reflecting and recycling light that would otherwise escape, while also allowing for improved heat dissipation with a heat sink and efficient outcoupling structures.
Implementation Method 1
a light guide adapted for receiving the light with the first spectral distribution from the plurality of light sources at the at least three side light input surfaces, guiding the light to a light exit surface, converting at least a part of the light with the first spectral distribution to light with a second spectral distribution
Implementation Method 2
This configuration significantly increases the amount of light extracted from the exit surface, enhancing brightness and efficiency by reflecting and recycling light that would otherwise escape
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A light emitting device comprising a plurality of light sources (211, 221, 231, 241) adapted for, in operation, emitting light (13) with a first spectral distribution, a light guide (4) comprising at least three side light input surfaces (41, 43, 44, 45) and a light exit surface (42), the at least three side light input surfaces and the light exit surface extending at an angle different from zero with respect to each other, the light guide being adapted for receiving the light with the first spectral distribution from the plurality of light sources at the at least three side light input surfaces, guiding the light to the light exit surface, converting at least a part of the light with the first spectral distribution to light (14) with a second spectral distribution and coupling at least a part of the light with the second spectral distribution out of the light exit surface, the light exit surface (42) having an area (A) and a circumference (C), the at least three side light input surfaces (41, 43, 44, 45) having a height (Hi) extending at an angle different from zero to a plane in which the light exit surface (42) extends, the circumference (C) of the light exit surface being more than four times larger than the height (Hi) of the side input surfaces and the area of the at least three side light input surfaces (41, 43, 44, 45) being less than four times the area (A) of the light exit surface (42).