LED Filament Viscosity Control for Uniform Fluorescent Powder Dispersion
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Solution Overview
Problem
LED filament bulbs face issues with light distribution due to precipitation of fluorescent powder in the covering glue, leading to subpar performance and failure to meet requirements.
Innovation Solution
A manufacturing method for LED filaments involving a support, chip fixing, first baking, dispensing of covering glue with a viscosity of 5000 to 50000 mPa·S, and a second baking process to ensure uniform dispersion and curing of the glue, preventing precipitation and ensuring good light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluorescent powder is mixed into covering glue, then the LED bulb can emit white light, but the fluorescent powder precipitates in the covering glue causing poor light distribution
Solution Approach 1:
The patent changes the viscosity parameter of the covering glue to a specific range (5000-50000 mPa·S) to prevent fluorescent powder precipitation while maintaining proper light distribution. This parameter optimization resolves the contradiction by finding the optimal viscosity that keeps fluorescent powder dispersed without causing aggregation.
Solution Approach 2:
The patent performs a first baking process before applying the covering glue to activate the adhesive properties of the glue in advance. This preliminary action ensures that when the covering glue is applied, it properly bonds and maintains the fluorescent powder dispersion, preventing precipitation during subsequent handling and use.
2Ease of manufacture
If covering glue with lower viscosity is used, then the glue flows better and covers uniformly, but the fluorescent powder precipitates more easily
Solution Approach 1:
The patent optimizes the viscosity parameter to a specific range (5000-50000 mPa·S) that balances flow characteristics with pigment suspension stability. This parameter change allows the glue to apply uniformly while preventing fluorescent powder precipitation, resolving the contradiction between ease of application and material stability.
3Strength
If the baking temperature is increased, then the adhesive bonding is stronger, but the fluorescent powder may aggregate and affect light distribution
Solution Approach 1:
The patent optimizes the baking temperature parameter to a specific range (40-80°C) that provides sufficient adhesive bonding without causing fluorescent powder aggregation. This parameter optimization ensures strong bonding while maintaining light distribution quality, resolving the contradiction between bonding strength and optical performance.
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 method results in high-yield LED filaments with stable and consistent light transmittance, meeting reliability and light flux requirements, and improving the overall performance of the LED bulb.
Implementation Method 1
fixing chips in which LED chips are fixed to the support with a die-attach adhesive
Implementation Method 2
performing a first baking in which the support fixed with the LED chips is placed in a baking device for baking
Implementation Method 3
performing a second baking in which the semi-finished product covered with the covering glue is placed into the baking device for baking, so as to obtain the LED filament after baking
Implementation Method 4
dispensing a glue in which a semi-finished product manufactured in S3 is covered with a covering glue with a viscosity of 5000 to 50000 mPa·S
Implementation Method 5
the viscosity of the covering glue is 5000 to 50000 mPa·S
Data Source
AI summary
A filament and a bulb are provided. The support in the filament includes a plurality of board bodies, and two adjacent board bodies are connected by a conductive connecting pin and an outer end of each of the board bodies at both ends is connected with a conductive pin. The bulb includes a lamp cap, a shell, a stem sealed with the shell, a conductive support fixed to the stem and a plurality of the LED filaments, the filaments are electrically connected to the conductive support.