LED Color Stability via Feedback Current Adjustment
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Solution Overview
Problem
LED displays and lighting systems face challenges in maintaining uniformity and longevity due to varying aging rates of different color LEDs, leading to color temperature and brightness changes, which affect the quality and reliability of the lighting output.
Innovation Solution
An integrated photonic device with a feedback mechanism that includes a light detector and driver system to monitor and adjust the current to each LED, ensuring uniform light output by comparing detected light properties with initial or user-defined values, and optionally utilizing a backup LED bank to maintain consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate LEDs of different colors are used to form a color image pixel, then the display can generate a full spectrum of colors, but the white point of the display moves as the different color LEDs age at different rates
Solution Approach 1:
The patent divides the lighting system into multiple separate LED banks, each emitting a different color (red, green, blue, yellow). Each LED bank is independently controlled by separate drivers, allowing individual adjustment of each color channel to compensate for differential aging and maintain overall color stability.
Solution Approach 2:
The system dynamically adjusts the intensity parameters of individual LED banks based on detected light output levels. The drivers modify current parameters to each LED bank to compensate for aging effects, maintaining consistent white point and color temperature over time.
2Duration of action of stationary object
If LED banks are used for lighting applications, then the system can provide extended operational life and reduced energy consumption, but uniformity is hard to achieve in manufacturing and color temperature changes occur as LEDs age
Solution Approach 1:
The system incorporates light detectors that continuously monitor the actual light output from each LED bank. This feedback information is used by the drivers to automatically adjust the intensity of each LED bank, compensating for manufacturing variations and aging effects to maintain uniform color temperature and brightness across the display.
Solution Approach 2:
The system transitions from static LED operation to dynamic control where the intensity of each LED bank can be independently adjusted in real-time. This allows the system to adapt to changing conditions and maintain uniformity throughout the extended operational life of the LEDs.
3Manufacturing precision
If individual optics and control are used for each color LED, then precise color control is achieved, but the device complexity increases
Solution Approach 1:
The patent combines multiple LED banks with different colors into a single integrated display structure. The individual optics and control mechanisms for each color LED are merged into a unified system where multiple LED banks share common structural elements and control architecture, reducing overall complexity while maintaining precise color control capability.
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 system maintains consistent light intensity and color temperature over time, prolongs the useful life of the device, and reduces manufacturing costs by relaxing binning requirements, ensuring uniform output and extending the device's operational lifespan.
Implementation Method 1
An LED emits light when a voltage is applied across a p-n junction formed by oppositely doping semiconductor compound layers
Implementation Method 2
A white light LED usually generates a polychromatic light through the application of one or more phosphors. The phosphors Stokes shift blue light or other shorter wavelength light to a longer wavelength
Data Source
AI summary
A lighting apparatus includes a board, a first light-emitting diode (LED) bank disposed on the board, a second LED bank disposed on the board, a light detector coupled to the first LED bank, and a driver coupled to the light detector and to each of the first and second LED banks. The first LED bank includes a plurality of first LEDs. The second LED bank includes a plurality of second LEDs, and is electrically coupled to the first LED bank. The light detector is configured to detect an output decay of light from each of the first LEDs. The second LEDs in the second LED bank are initially deactivated and are subsequently activated in response to light output decay of the first LEDs.