Light-Emitting Device with Light Guide for Two-Way Illumination
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Solution Overview
Problem
Conventional phosphor-based light-emitting devices face challenges such as light-energy losses, phosphor self-heating, and undesired light propagation due to the properties of luminescent materials, which affect their efficiency and durability.
Innovation Solution
A light-emitting device configuration featuring a base substrate with light-emitting elements, a scattering element, and an extractor element, including a reflector and a light guide, which utilizes refractive index differences and optical interfaces to optimize light scattering and reflection, reducing losses and enhancing two-way illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If phosphor-based light-emitting devices are used to generate white light, then luminous efficacy and longevity are improved, but light-energy losses and phosphor self-heating occur due to Stokes loss
Solution Approach 1:
The patent segments the light emission process into two separate LED chips: one emitting blue light and another emitting yellow light. This eliminates the need for phosphor conversion, thereby avoiding Stokes loss and the associated energy waste while maintaining high luminous efficacy and longevity.
Solution Approach 2:
The patent extracts the phosphor conversion step from the light-emitting device entirely. By removing the phosphor layer and its associated Stokes loss, the device achieves higher energy efficiency while still producing white light through direct emission from multiple LED chips.
2Illumination intensity
If phosphor-based light-emitting devices are used, then white light generation is achieved, but phosphor self-heating occurs from Stokes loss
Solution Approach 1:
The patent segments the white light generation into two separate LED emission sources (blue and yellow) instead of using a single blue LED with phosphor conversion. This eliminates the phosphor layer that would otherwise self-heat due to Stokes loss, while still achieving effective white light illumination.
3Device complexity
If conventional light-emitting devices are used, then simple structure is maintained, but light propagation occurs in undesired directions due to random emission from phosphor
Solution Approach 1:
The patent introduces a reflective cup structure as an intermediary element between the LED chips and the environment. This reflective cup captures light emitted in undesired directions and redirects it toward the intended illumination path, thereby controlling light propagation without significantly increasing device 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
The configuration improves light distribution and reduces energy losses by scattering and reflecting light effectively, providing efficient two-way illumination while minimizing heat-related issues and maintaining the longevity of the light-emitting elements.
Implementation Method 1
a first optical element having a first surface spaced apart from the LEEs and positioned to receive light from the LEEs, where the first optical element includes scattering centers arranged to scatter light from the LEEs
Implementation Method 2
there being an optical interface between the first and second optical elements at the place of contact, where a medium adjacent to the first surface of the first optical element has a refractive index n0; the first optical element includes a first material having a first refractive index n1, where n01; the second optical element includes a second material having a refractive index n2, where n02
Implementation Method 3
a reflector element adjacent the second optical element, where the reflector element has first and second surfaces extending away from the exit surface, and the reflector element is arranged to reflect a first portion of light from the second optical element
Implementation Method 4
the exit surface is shaped such that an angle of incidence on the exit surface of the light provided by the first optical element that directly impinges on the exit surface is less than a critical angle for total internal reflection
Data Source
AI summary
A variety of light-emitting devices are disclosed that are configured to manipulate light provided by one or more light-emitting elements (LEEs). In general, a light-emitting device includes one or more light-emitting elements (LEEs) disposed on a base surface that are configured to emit light, a first optical element having a first surface spaced apart from the LEEs and positioned to receive light from the LEEs, a transparent second optical coupled to the first optical element, and a reflector element adjacent the second optical element arranged to reflect a portion of light output from the second optical element.