Light Emitting Device Hue Uniformity via Local Phosphor Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Densely mounted light-emitting devices with phosphor-containing resin face challenges in achieving uniform light hue due to varying light travel distances through the phosphor layer, causing intensity variations and color deviations from the designed hue.
Innovation Solution
The light-emitting device features a board with densely mounted light-emitting elements, where the space between adjacent elements is set between 5 μm and 120% of the average phosphor particle size, ensuring consistent light travel distance and using a seal resin with different phosphors excited by the elements, deposited on their surfaces to maintain uniform chromaticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If multiple light-emitting elements are mounted densely to reduce emission region size, then light condensation property is improved, but the actual hue of emitted light deviates from desired hue due to varying light travel distances through phosphor layer
Solution Approach 1:
The patent applies local quality by creating phosphor-free spaces between adjacent light-emitting elements. These localized regions without phosphor ensure that light traveling through different paths (from different element surfaces) experiences consistent phosphor concentration, thereby maintaining uniform hue across the entire emission region while allowing dense mounting of multiple elements
2Productivity
If space between light-emitting elements is reduced to achieve compact emission region, then light condensation property is improved, but manufacturing precision deteriorates due to difficulty in controlling phosphor distribution and light travel distance variations
Solution Approach 1:
The invention introduces local phosphor-free zones between adjacent light-emitting elements. This local modification allows the system to maintain very small spacing (5 μm or more but sufficiently small for compact emission) while ensuring that light from different element surfaces travels through consistent phosphor concentrations, thereby achieving both high productivity through compact design and high manufacturing precision through uniform chromaticity control
3Illumination intensity
If phosphor is dispersed in seal resin to cover light-emitting elements, then light emission intensity is improved, but hue uniformity deteriorates due to varying light travel distances through phosphor layer from different element surfaces
Solution Approach 1:
The patent creates a non-uniform phosphor distribution pattern where phosphor is present in regions away from element surfaces but absent in the spaces between adjacent elements. This local quality adjustment ensures that light from different element surfaces (which would otherwise travel different distances through phosphor) instead travels through regions with consistent phosphor concentration, maintaining hue uniformity while preserving overall light emission intensity through phosphor in other regions
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 reduces hue deviation, achieving uniform light emission with improved light condensation properties and efficiency by maintaining consistent light travel distance and phosphor concentration.
Implementation Method 1
LED elements emitting light such as blue light are sealed with a resin containing a phosphor, which is excited by the light from the LED elements to yield light that is mixed therewith to provide light such as white light
Data Source
AI summary
A light-emitting device and a manufacturing method thereof are provided, which device yields light exhibiting an actual hue with a deviation reduced as much as possible from a designed hue value, wherein the light is a mixture of light emitted from densely-mounted light-emitting elements and excited light from a phosphor contained in a resin sealing the light-emitting elements. The light-emitting device includes a board, light-emitting elements mounted densely on the board so that light-emitting surfaces thereof face opposite to the board, and a seal resin containing a plurality of different phosphors and covering all of the light-emitting elements, wherein the phosphors are excited by light from the light-emitting elements and deposited on upper surfaces of the light-emitting elements. A space between adjacent light-emitting elements has a length of 5 μm or more and 120% or less of a median diameter D50 of a phosphor which has the largest average particle size of the phosphors.