LED Color Tuning via Current Division and TIR Lens
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Solution Overview
Problem
The challenge in mass-producing LED-based lamps for general illumination lies in achieving consistent color temperature, as existing methods require active feedback mechanisms and are costly, and LEDs' color characteristics are not stable over time.
Innovation Solution
The use of independently addressable groups of LEDs with a total-internal-reflection (TIR) color-mixing lens allows for controllable division of input current to achieve a desired color temperature, eliminating the need for active feedback components by stabilizing the color during manufacturing and ensuring consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If active feedback mechanisms are used to maintain color temperature, then color consistency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies preliminary action by pre-tuning the relative brightness of white and red LEDs during the manufacturing process to achieve the desired color temperature. This initial configuration is stored in memory, and the system maintains color consistency without requiring active feedback during operation, thereby resolving the contradiction between color consistency and device complexity
Solution Approach 2:
The system uses self-service by relying on the inherent stability of LEDs with color stable over time to maintain color temperature without external feedback. The pre-configured LED combinations automatically maintain desired color characteristics, eliminating the need for sensors, analyzers, and adjustment mechanisms
2Manufacturing precision
If a large number of bins are used for LED color temperature selection, then color temperature consistency is improved, but manufacturing yield decreases
Solution Approach 1:
The patent changes the parameter approach from selecting LEDs from multiple narrow color temperature bins to adjusting the relative brightness of LEDs with broader color characteristics. By controlling the ratio of white to red LED output, the system achieves precise color temperature control while accepting LEDs from wider bins, thereby improving manufacturing yield without sacrificing color consistency
3Stability of the object's composition
If LEDs with color stable over time are used, then long-term color consistency is improved, but the ability to compensate for LED degradation is reduced
Solution Approach 1:
The patent extracts the feedback and adjustment components from the system, relying solely on the inherent color stability of selected LEDs. By removing the complexity of active compensation mechanisms, the system achieves reliability through the natural stability of high-quality LEDs whose color characteristics remain consistent over their operational lifetime
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 the production of lamps with reduced color variation and stable color temperature over time, reducing manufacturing costs and eliminating the need for active feedback mechanisms, allowing for high-precision color tuning in a mass-production environment.
Implementation Method 1
The lamps can also include a total-internal-reflection (TIR) color-mixing lens to produce light of a uniform color by mixing the light from the different groups of LEDs
Data Source
Figure 1A~1B
Figure 2A~2B
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AI summary
Apparatus and methods are provided for tuning the color of an LED-based lamp (100) to a desired color or color temperature. The lamp (100) can include two or more independently addressable groups of LEDs associated with different colors or color temperatures. The color (or color temperature) of the output light is tuned by controllably dividing an input current among the groups of LEDs. An optimal division of the input current is determined based on a linear interpolation between measured values of color or color temperature produced by at least two different divisions of the input current. Tuning can be performed once, e.g., during manufacture, and the lamp (100) does not require active feedback components for maintaining color temperature.