Light-emitting Device with Patterned Phosphor Film for Color Evenness
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Solution Overview
Problem
Light-emitting devices with phosphor layers exhibit color unevenness due to differences in emission chromaticity between regions, particularly where the phosphor layer is directly above a light-reflecting member, leading to visual color inconsistencies.
Innovation Solution
A light-emitting device design featuring face-down mounted light-emitting elements with a phosphor-containing film and a transparent plate, where the phosphor-containing film is not covering the region directly above the gap between elements, and a white reflector covers the side surfaces of both the light-emitting elements and the phosphor-containing film, except above the gap, to enhance brightness and color evenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor layer is provided directly above the light-reflecting member to improve light extraction, then luminance is improved, but color unevenness occurs due to different emission chromaticity in different regions
Solution Approach 1:
The phosphor layer is selectively positioned only in regions where light-emitting elements are located, while intentionally excluding the region directly above the light-reflecting member. This local differentiation ensures that phosphor is applied where needed for color conversion but avoided where it would cause color unevenness due to reflected light interference.
Solution Approach 2:
The light-emitting device structure is segmented into distinct functional zones: the light-emitting element region with phosphor layer for color conversion, and the light-reflecting member region without phosphor to maintain uniform chromaticity. This spatial segmentation resolves the contradiction by assigning different material properties to different functional zones.
2Illumination intensity
If the phosphor layer covers the entire surface including above the light-reflecting member, then light extraction is improved, but the device complexity increases due to additional manufacturing steps to prevent color unevenness
Solution Approach 1:
The phosphor layer is applied selectively only to regions above light-emitting elements using a simple mask or selective deposition technique, avoiding the need for complex post-manufacturing adjustments. This approach maintains light extraction efficiency while simplifying the manufacturing process by integrating the patterned application into the standard fabrication流程.
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 achieves high brightness and color evenness by optimizing light extraction efficiency and reducing thermal stress on the reflector, thereby minimizing color unevenness and improving the reliability of the light-emitting device.
Implementation Method 1
a phosphor layer with a phosphor included therein... light emitted from the region has a large proportion of fluorescence
Implementation Method 2
light laterally emitted from the light-emitting element is reflected by the light-reflecting member so as to improve luminance
Data Source
AI summary
A light-emitting device includes a plurality of light-emitting elements face-down mounted on a substrate, a phosphor-containing film on the plurality of light-emitting elements directly or via a transparent adhesive layer, a transparent plate provided on the phosphor-containing film so as to directly contact the film, and a white reflector to cover a side surface of the plurality of light-emitting elements and, of side surfaces of the phosphor-containing film, at least a side surface not located above a gap between the plurality of light-emitting elements. At least a portion of a region directly above the gap is not covered with the phosphor-containing film.