Graded Phosphor Sheet for LED Thermal Protection
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Solution Overview
Problem
Traditional light emitting devices experience phosphor deterioration and non-uniform color emission due to direct contact between phosphor and light emitting diode, leading to reduced lifespan and increased volume.
Innovation Solution
A phosphor sheet with a gradually increasing concentration of phosphor powder from the light source side to the opposite side, formed by mixing phosphor powder with an adhesive material, having a smooth surface for light reception and a rough surface for scattering, reducing direct contact and optimizing light projection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If phosphor and resin material are placed in direct contact with the light emitting diode device, then the light emitting device can be compact, but the phosphor deteriorates due to heat causing wavelength changes and reduced efficiency
Solution Approach 1:
The phosphor concentration in the resin material is designed to vary spatially, being lower near the light emitting diode (where heat is generated) and higher farther away. This non-uniform distribution allows the phosphor to be protected from thermal damage while still achieving effective light conversion across the entire resin volume.
2Ease of manufacture
If phosphor concentration is uniformly distributed in the resin material, then the manufacturing process is simple, but the emitted light color is non-uniform due to non-uniform wavelength changes
Solution Approach 1:
The phosphor concentration is deliberately made non-uniform, with lower concentration near the heat source and higher concentration farther away. This spatial variation in phosphor distribution compensates for the non-uniform thermal effects, resulting in uniform light emission color across the entire device.
3Reliability
If extra resin material and reflective mask are added to insulate the phosphor plate, then the phosphor is protected from heat damage, but the volume of the light emitting device significantly increases
Solution Approach 1:
The protective function previously requiring separate components (resin material and reflective mask) is integrated directly into the resin material itself by controlling the phosphor concentration distribution. The resin material simultaneously serves as both the protective medium and the light conversion medium, eliminating the need for additional insulating components.
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 phosphor sheet design extends the lifespan of light emitting devices, reduces volume, and enhances light efficiency by preventing phosphor deterioration and minimizing light reflection.
Implementation Method 1
a phosphor sheet that has phosphor powder within it, and the concentration of the phosphor powder within the phosphor sheet has a gradually increasing or decreasing distribution based on the different positions and different distances towards the light source
Data Source
AI summary
The phosphor sheet of the present invention mainly includes a sheet material that is formed by mixing and solidifying of a phosphor powder and an adhesive material. The sheet material subsequently forms a first surface that receives a light source, and forms a second surface that is located on the opposite side to the first surface for scattering a light source. In addition, the distribution ratio of the phosphor powder as well as the adhesive material within the phosphor sheet is based mainly on the different positions and different distances towards the light source; the distribution ratio of the phosphor powder and the adhesive material increases gradually from the first surface towards the second surface. The phosphor of the present invention is designed to be a sheet material, so as to enable the overall volume of the light emitting device to be reduced. Moreover, distribution ratio of the phosphor powder that is within the phosphor sheet is based on the different positions and different distances towards the light source; and the concentration of the phosphor powder increases gradually from the positions that are closest to the light source to the positions that are furthest away from the light source, so as to prevent the part of highly concentration of phosphor powder within the phosphor sheet coming in direct contact with the light emitting heat source, and thereby causing the deterioration of the phosphor sheet. This may then enables the life span of the light emitting device to be increased.