Dynamic Phosphor Jetting for LED Color Consistency
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Solution Overview
Problem
The manufacturing of broad-spectrum light emitting diodes (LEDs) faces challenges in achieving consistent optical properties due to operator errors, settling of phosphor suspensions, and viscosity changes, leading to color inconsistency and increased production costs.
Innovation Solution
A method and system for dispensing a phosphor composition onto LEDs using jetting heads with feedback control, where expected characteristics are input, and the relative amounts of pure silicone and colored phosphors are adjusted based on real-time light detection to achieve desired color temperature and color coordinates, ensuring precise control and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphor particles are suspended in silicone carrier using conventional processes, then phosphor composition can be applied to LEDs, but uniformity of light and color consistency deteriorate due to settling and viscosity changes
Solution Approach 1:
The phosphor suspension process is segmented into multiple stages: initial mixing at high speed to distribute phosphor particles, followed by lower speed mixing to maintain uniformity, and finally jetting individual droplets onto each LED. This segmentation prevents settling by continuously renewing the suspension rather than maintaining a static mixture.
Solution Approach 2:
The system incorporates feedback control where the mixing process is monitored and adjusted in real-time. The mixer speed and duration are controlled based on feedback signals to maintain optimal phosphor suspension uniformity throughout the mixing cycle, preventing settling before jetting.
2Ease of manufacture
If pre-defined mixture and dispensing volume are used, then manufacturing process is simplified, but operator error and process variation lead to off-color failures
Solution Approach 1:
The system replaces manual mixing and visual inspection with automated jetting technology. Instead of relying on operators to manually mix phosphor suspensions and dispense them onto LEDs, the system uses computer-controlled jetting heads that automatically deposit precise amounts of phosphor onto each LED, eliminating operator error.
Solution Approach 2:
The system dynamically adjusts mixing parameters (speed, duration) and jetting parameters (droplet size, placement position) based on real-time feedback. This allows the system to maintain optimal color consistency by adapting to variations in phosphor suspension properties during the manufacturing process.
3Manufacturing precision
If multiple fabrication steps are used to ensure color consistency, then optical properties improve, but manufacturing time and cost increase
Solution Approach 1:
The system merges multiple fabrication steps into a single integrated jetting process. Mixing, dispensing, and curing are combined into one continuous operation where phosphor is jetted directly onto the LED in precise droplets that self-align and cure immediately, eliminating the need for separate mixing, dispensing, and positioning steps.
Solution Approach 2:
The system performs preliminary mixing of phosphor suspension before jetting, ensuring uniform distribution of phosphor particles in advance. This preliminary action prevents the need for post-jetting adjustments or rework, maintaining high productivity while ensuring color consistency.
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 enables precise control of light characteristics, reducing variability and the need for binning, thereby improving production yield and reducing costs by eliminating the need for pre-mixing and ensuring consistent color across large numbers of LEDs.
Implementation Method 1
A first amount of the phosphor composition is dispensed onto a surface of the light emitting device utilizing a plurality of jetting heads
Implementation Method 2
A pulsed power is applied to the light emitting device, causing the light emitting device to emit light
Implementation Method 3
the light emitting device to emit light, which is then detected with a light detector
Data Source
AI summary
A system and method for depositing a phosphor composition onto a light emitting device improves manufacturing yield, simplifies conventional processes, and decreases costs. For example, a method of dispensing a phosphor composition onto a light emitting device includes dispensing a portion of the phosphor composition onto the light emitting device utilizing a plurality of colored phosphor dispensers each for dispensing a respective type of phosphor. Power is applied to the light emitting device to emit light, and a characteristic the light emitted by the light emitting device is detected. Phosphor mixing and phosphor dispensing are dynamically controlled. Therefore the color characteristics of phosphor dispensed on LEDs are consistent. The system and method may also reduce the difference between detected characteristic of the light and a desired characteristic of the light.