Multi-Stage LED Circuit for Dimming-Driven Color Temperature Control
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Solution Overview
Problem
Conventional LED lighting systems lack the ability to dynamically adjust color temperature in response to changes in brightness, similar to incandescent bulbs, which limits their ability to provide a user-defined lighting experience.
Innovation Solution
A lighting apparatus with an LED circuit comprising serially connected stages, including a first path with a first LED and a second path in parallel with a second LED, both emitting light with different color temperatures, and a driving current controller that adjusts the intensity of light output based on a dimming signal, allowing for precise control of color temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional LED lighting systems are used to provide stable light output, then energy efficiency is improved, but the ability to dynamically adjust color temperature with brightness is lost
Solution Approach 1:
The LED lighting system is segmented into multiple independent LED strings, each containing LEDs with different color temperatures. This segmentation allows each string to be controlled independently, enabling dynamic color temperature adjustment while maintaining overall energy efficiency. The patent divides the lighting system into first LED strings (higher color temperature) and second LED strings (lower color temperature) that can be selectively activated based on desired output characteristics.
Solution Approach 2:
The system implements dynamic control by varying the driving currents to different LED strings based on the desired dimming level. As the overall brightness is reduced, the controller dynamically shifts the ratio of current allocation between high-color-temperature and low-color-temperature LED strings, thereby dynamically adjusting the perceived color temperature. This dynamic behavior replicates the incandescent bulb characteristic where color temperature changes with brightness.
2Adaptability or versatility
If incandescent bulbs are used to achieve color temperature change with brightness adjustment, then user-defined lighting experience is improved, but energy consumption increases
Solution Approach 1:
The system changes the electrical parameters (driving currents) to multiple LED strings with different color characteristics to achieve the desired color temperature effect. By adjusting the current ratios to high and low color temperature LED strings, the system simulates the incandescent color temperature transition without the associated energy waste, as LEDs inherently operate more efficiently across different current levels.
Solution Approach 2:
The lighting system uses a composite approach by combining multiple LED types with different color temperatures in parallel strings. This composite LED architecture allows the system to leverage the efficiency of LED technology while achieving the color temperature variability traditionally associated with incandescent bulbs, effectively creating a hybrid performance characteristic.
3Adaptability or versatility
If multiple LED strings with different color temperatures are used, then color temperature control is improved, but device complexity increases
Solution Approach 1:
The circuit is segmented into distinct parallel LED strings with different color temperatures, where each string can be independently controlled. This segmentation simplifies the control architecture by allowing independent current regulation for each string, making it easier to implement color temperature adjustment logic compared to using a single complex LED assembly with multiple phosphors or converters.
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
Enables the lighting apparatus to simulate the color temperature change with brightness adjustment, providing a user-defined lighting experience similar to incandescent bulbs by effectively controlling the color temperature of the output light.
Implementation Method 1
each of the stages including a first path including a first resistor and a first LED connected in series, and a second path connected to the first path in parallel and including a second LED configured to emit light having a color temperature different from that emitted from the first LED
Implementation Method 2
The first LED may include first light-emitting cells and a first wavelength conversion layer covering the first light-emitting cells, and the second LED may include second light-emitting cells and a second wavelength conversion layer different from the first wavelength conversion layer
Data Source
AI summary
A lighting apparatus including an LED circuit including a plurality of serially connected stages configured to receive a modulated rectified voltage, each of the stages including a first path including a first resistor and a first LED connected in series, and a second path connected to the first path in parallel and including a second LED configured to emit light having a color temperature different from that emitted from the first LED, and a driving current controller configured to adjust an intensity of light output from the LED circuit by adjusting currents applied to driving nodes connected to the stages, depending on a dimming signal associated with a dimming level of the rectified voltage, in which a threshold voltage of the first LED is lower than that of the second LED.