Phosphor Layer Thickness Control via Optical Feedback
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Solution Overview
Problem
There is a need for an efficient method to form a phosphor layer in light-emitting device packages, particularly for white LEDs, as existing techniques lack precision and effectiveness in achieving the desired thickness and uniformity of the phosphor layer.
Innovation Solution
A method involving a carrier with a phosphor layer, where a test light-emitting device emits light through the phosphor layer, and a photodetector analyzes the transmitted light to determine the thickness based on luminous intensity ratios, allowing real-time adjustment of the mold to achieve the desired thickness, and subsequent division into discrete layers for attachment to light-emitting chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coating methods are used to form a phosphor layer, then the formation process is simple, but the thickness uniformity and precision are insufficient
Solution Approach 1:
The patent implements a feedback control system where a test light-emitting device emits light through the phosphor layer during formation, a photodetector analyzes the transmitted light to determine thickness in real-time, and the mold position is adjusted based on this feedback to achieve the desired thickness. This closed-loop control resolves the contradiction by enabling precise thickness control without requiring overly complex multi-step processes.
Solution Approach 2:
The patent replaces conventional mechanical thickness measurement and control methods with an optical measurement system. Instead of using mechanical gauges or post-processing inspection, the system uses light transmission and photodetector analysis to non-contact, real-time measure phosphor layer thickness, thereby achieving high precision without adding mechanical complexity to the fabrication process.
2Manufacturing precision
If real-time thickness measurement and adjustment is implemented, then the phosphor layer thickness precision is improved, but the fabrication time increases
Solution Approach 1:
The patent maintains continuous fabrication flow by performing thickness measurement and adjustment during the phosphor layer formation process itself, rather than as a separate post-processing step. The test light-emitting device and photodetector operate continuously during coating, enabling real-time feedback without interrupting the manufacturing sequence, thus avoiding time loss despite the added precision requirements.
3Reliability
If conventional phosphor layer formation methods are used, then the fabrication process is simple, but the light emission performance is insufficient
Solution Approach 1:
The patent uses feedback control during phosphor layer formation to ensure optimal thickness for light emission performance. The test light-emitting device simulates actual operating conditions, and the photodetector provides real-time thickness data that is used to adjust the mold position, ensuring the phosphor layer achieves the precise thickness needed for reliable and efficient light emission.
Solution Approach 2:
The patent performs preliminary thickness verification and adjustment during the formation process itself, before the phosphor layer is finalized and attached to the light-emitting chip. This preliminary action ensures that the phosphor layer is formed with the correct thickness and optical properties from the start, preventing performance issues that would require rework or lead to unreliable light emission.
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 method enables precise and efficient formation of phosphor layers, improving the light-emitting device's performance by ensuring optimal thickness and uniformity, leading to enhanced light emission characteristics and reduced fabrication time and costs.
Implementation Method 1
emitting first light from a test light-emitting device toward the second surface of the carrier, and analyzing second light included in the first light and passing through the phosphor layer
Implementation Method 2
calculating a ratio of luminous intensity of the second transmitted light to luminous intensity of the first transmitted light
Data Source
AI summary
A method of fabricating a light-emitting device package includes preparing a carrier including a first surface and a second surface disposed opposite the first surface, forming a phosphor layer on the first surface of the carrier, emitting first light from a test light-emitting device toward the second surface of the carrier, analyzing second light passing through the phosphor layer, and determining a thickness of the phosphor layer based on the analysis.