LED Phosphor Sheet Lamination for Uniform Color Field
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Solution Overview
Problem
Existing methods for laminating a wavelength converting layer over light emitting devices result in non-uniform thickness, leading to variations in the color field of emitted light due to the stretching of the phosphor layer over the sides and edges of LEDs during the lamination process.
Innovation Solution
A wavelength converting film is applied over the top surface and sidewalls of LEDs, with a thickness gradient where the top surface has a reduced thickness compared to the sidewall, and a third lamination process is used to further thin the film over the tops of the LEDs using a flattening element to ensure uniformity, thereby adjusting the color field of emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wavelength converting film is laminated over LED chips using conventional methods, then the film covers the top surface and sidewalls, but the thickness becomes non-uniform due to stretching over the sides and edges, causing color field variations
Solution Approach 1:
The patent applies different thickness characteristics to different regions of the wavelength converting film. The top surface portion is designed with reduced thickness compared to the sidewall portions, creating local thickness variations that compensate for the stretching effect during lamination. This local quality adjustment ensures uniform color field across the LED array by preventing excessive phosphor material accumulation on the sidewalls.
2Shape
If the phosphor layer is stretched over the sides and edges of LEDs during lamination, then complete coverage is achieved, but thickness non-uniformity increases leading to color variations in the emitted light
Solution Approach 1:
The patent performs preliminary thickness adjustment by reducing the film thickness at the top surface portion before the lamination process. This preliminary action anticipates the stretching that will occur during lamination and pre-compensates for it, ensuring that when the film is stretched over the LED sidewalls, the final thickness distribution produces uniform color output across the entire LED array.
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 approach improves the uniformity of the wavelength converting film thickness, enhancing the performance of the light emitting device by minimizing color variations across the light field, ensuring a consistent emission spectrum.
Implementation Method 1
A wavelength converting film is disposed over a top surface and a sidewall of the LED
Data Source
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AI summary
A method for laminating a film over a light emitting diode (LED), where the thickness of a portion of the film disposed over the top surface of the LED is reduced by pressing a flattening element against the top surface of the LED. The resulting form of the phosphor encapsulation allows for an improved color homogeneity.