LED Dimming Circuit with Segmented Color Temperature Control
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Solution Overview
Problem
Conventional incandescent lamps experience inefficient energy consumption and unstable operating states during dimming, as they shift towards warmer light spectra, leading to a change in color temperature that is not efficiently simulated by existing LED technologies.
Innovation Solution
An operating circuit with a high-frequency clocked second current source is used to control the auxiliary LED line, ensuring that energy is not converted to thermal energy, and the auxiliary current is managed based on voltage thresholds to maintain stable operation and simulate color temperature changes during dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a passive compensation branch is used to reduce voltage across LEDs to adjust color temperature, then color temperature control is achieved, but electrical power is thermally converted leading to high energy consumption
Solution Approach 1:
The LED lighting system is segmented into multiple LED strings with different color temperatures (e.g., warm white, neutral white, cool white). Each string can be independently controlled to achieve desired color temperature without thermal conversion losses. This allows precise color temperature adjustment by varying the intensity of each LED string rather than using passive voltage compensation that wastes energy as heat.
Solution Approach 2:
The system dynamically adjusts the current distribution to different LED strings based on the desired color temperature and dimming level. By actively controlling the ratio of current to each LED string, the system achieves color temperature control without the energy-wasting passive compensation approach. The current distribution is continuously optimized to maintain efficiency across all dimming levels.
2Temperature
If conventional light bulbs are dimmed to change color temperature, then warmer light is perceived, but energy efficiency remains very low
Solution Approach 1:
The system changes the spectral parameters by selectively adjusting the intensity of different LED strings with distinct color temperatures. Instead of reducing overall power consumption (which causes the efficiency loss in conventional bulbs), the system maintains high efficiency by using LED technology and achieves color temperature variation by changing the relative contribution of each LED string to the total light output.
3Temperature
If multiple LED types are used to generate mixed light, then color temperature control is achieved, but unstable operating states occur during dimming
Solution Approach 1:
The control unit receives feedback about the actual current distribution and luminous output from multiple LED strings. Based on this feedback, the control unit dynamically adjusts the current allocation to maintain stable operation and achieve the desired color temperature and dimming level without unstable operating states. The feedback mechanism ensures coordinated control of all LED strings.
Solution Approach 2:
The control unit serves multiple functions: it controls the current distribution to different LED strings for color temperature adjustment, manages the dimming level, and maintains operational stability. This multi-functional control approach coordinates all aspects of LED operation from a single control point, preventing unstable states that could arise from independent control of each function.
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 solution allows for efficient energy use and stable operation by preventing thermal energy conversion and maintaining consistent color temperature changes during dimming, enhancing the energy efficiency and reliability of LED lighting systems.
Implementation Method 1
the light is generated by mixing longer-wave light from at least one first LED and shorter-wave light from at least one second LED
Implementation Method 2
an auxiliary LED line with at least one LED of a second type
Implementation Method 3
a blue light or UV light-emitting LED chip that covered with a phosphor layer that converts the blue light or UV light into a longer-wavelength light of a correspondingly different colour
Data Source
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AI summary
An operating circuit for an LED series (30) with at least one LED (31-39) of a first type (w) and an auxiliary LED series (70) with at least one LED (63) of a second type (a) is designed to be preferably supplied by a first current source with an adjustable, preferably regulated, overall current (IG). A main current (I1) through the LED series (30) is directly supplied by the overall current (IG). The operating circuit also has a second current source (60), which is supplied by the overall current (IG) and supplies an auxiliary current (I2) to the auxiliary LED series (70). The operating circuit further has a control circuit (40), which controls the second current source (60) on the basis of a voltage (UG) on the LED series (30).