Inclined Plate Wavelength Conversion Members for High Luminous Flux
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Solution Overview
Problem
Existing light-emitting devices with semiconductor elements and phosphor wavelength conversion members suffer from energy loss due to absorption and scattering, leading to decreased efficiency and inability to produce high luminous flux, and have complex structures requiring multiple optical parts.
Innovation Solution
A light-emitting device with a semiconductor light-emitting element and multiple plate-like wavelength conversion members inclined relative to the optical axis, containing fluorescent material to absorb and emit visible light, minimizing energy loss and thickness while maximizing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the phosphor is increased to suppress excitation light leakage, then excitation light leakage is reduced, but light resorption and scattering increase causing energy loss and decreased luminous efficiency
Solution Approach 1:
The phosphor layer is divided into multiple segments arranged in a microlens array structure. Each microlens element focuses excitation light onto a corresponding phosphor particle, creating multiple discrete conversion points rather than a continuous thick layer. This segmentation allows effective excitation light utilization while maintaining thin overall structure, reducing resorption and scattering losses.
Solution Approach 2:
The invention transitions from a conventional planar phosphor layer to a three-dimensional microlens array structure with focal points distributed in space. The microlenses are positioned at specific heights above the phosphor particles, creating a vertical dimension that enables focused light delivery without requiring increased horizontal phosphor thickness. This dimensional change achieves effective excitation suppression while minimizing light path length through the phosphor material.
2Reliability
If a conventional structure with light-guiding plate and cylindrical lens is used to create surface light-emitting source, then excitation density is reduced, but device complexity increases requiring many optical parts
Solution Approach 1:
The invention merges the functions of the light-guiding plate, cylindrical lens, and phosphor layer into a single integrated microlens array structure. The microlens array simultaneously performs light guiding, focusing, and wavelength conversion functions that were previously distributed across multiple separate optical components. This integration dramatically reduces device complexity while maintaining the surface light-emitting source functionality with low excitation density.
Solution Approach 2:
The microlens array structure serves multiple functions: it acts as a light-guiding structure, focuses excitation light onto phosphor particles, and positions the phosphor in a configuration that creates a surface light-emitting source. This multi-functional design eliminates the need for separate light-guiding plates, cylindrical lenses, and phosphor coatings, reducing the total number of optical parts while achieving the desired low excitation density surface emission.
3Productivity
If excitation light is concentrated at one point of the phosphor to create high brightness point light source, then light extraction efficiency is improved, but excitation density increases causing material deterioration and decreased light-emitting efficiency
Solution Approach 1:
Instead of concentrating excitation light at a single point, the invention segments the light concentration into multiple focal points corresponding to individual microlens elements. Each microlens focuses light onto a separate phosphor particle or small region, distributing the high excitation density across many discrete locations rather than one point. This maintains high local excitation efficiency while preventing material deterioration through distribution of stress and heat.
Solution Approach 2:
The invention creates focal points distributed in three-dimensional space above the phosphor layer, with microlenses positioned at various heights. This spatial distribution in multiple dimensions allows each focal point to achieve high excitation efficiency while the overall structure prevents excessive concentration at any single location. The vertical positioning of microlenses creates a layered focal point distribution that maintains reliability while achieving high light extraction efficiency.
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 enables low energy loss, high luminous flux output, and a large light-emitting area with a simplified structure, suitable for applications requiring high luminous flux like lighting and image display.
Implementation Method 1
each plate-like wavelength conversion member containing a fluorescent material which is capable of absorbing the excitation light and outputting a visible light having a different wavelength from that of the excitation light
Data Source
AI summary
A light-emitting device which includes a semiconductor light-emitting element, and a plurality of plate-like wavelength conversion members which are disposed to face the semiconductor light-emitting element and are inclined with respect to the optical axis of excitation light emitted from the semiconductor light-emitting element, the plate-like wavelength conversion members containing respectively a fluorescent material which is capable of absorbing the excitation light and outputting light having a different wavelength from that of the excitation light, and the plate-like wavelength conversion members as a whole emitting visible light.