Warm Dimming LED Light Source Using Parallel Color Temperature Segments
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Solution Overview
Problem
Current LED dimming technologies require complex control circuitry and multiple components to achieve a color temperature shift similar to incandescent lamps, which is inefficient and not easily integratable with existing LED systems.
Innovation Solution
A lighting device utilizing a first LED light source with a higher color temperature and a second LED light source with a lower color temperature connected in parallel, with control circuitry applying variable duty cycle frequency modulated power to the first source while providing continuous power to the second source, allowing for a seamless color temperature shift during dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED dimming is implemented using conventional methods (single LED source with pulse width modulation), then power consumption is reduced and brightness is lowered, but the color temperature remains substantially the same or shifts to a higher value instead of decreasing like incandescent lamps
Solution Approach 1:
The LED light source is segmented into multiple LED chips with different color temperatures (e.g., first LED chips with higher color temperature and second LED chips with lower color temperature). By independently controlling the brightness of each segment, the system can achieve both dimming and color temperature shifting effects, resolving the contradiction between reducing illumination intensity and maintaining appropriate color temperature characteristics.
Solution Approach 2:
Different regions of the LED light source are assigned different color temperature characteristics. The first LED chips emit higher color temperature light while the second LED chips emit lower color temperature light. By adjusting the local quality (color temperature) of different LED segments according to their respective luminous flux gradients, the system achieves natural-looking dimming with color temperature transition similar to incandescent lamps.
2Temperature
If multiple LED segments with different color temperatures are used to achieve color temperature shift during dimming, then color temperature characteristics improve, but device complexity and control circuitry requirements increase significantly
Solution Approach 1:
The system utilizes the inherent negative temperature coefficient characteristics of LED luminous flux to automatically achieve color temperature shifting during dimming. By selecting LED chips with appropriate luminous flux gradients and connecting them in parallel with balanced forward voltages, the system self-regulates the color temperature transition without requiring complex active control circuitry, switches, or microcontrollers.
Solution Approach 2:
The invention changes the electrical parameters (forward voltage and luminous flux gradient) of the LED chips to achieve the desired color temperature characteristics. By carefully selecting LED chips with specific electrical characteristics and connecting them in parallel, the system achieves natural color temperature transition during dimming through passive parameter matching rather than active control.
3Device complexity
If LEDs with different color temperatures and specific luminous flux outputs are selected and connected in parallel with balanced forward voltages, then color temperature shift during dimming is achieved with minimal components, but the selection and matching process becomes more complex
Solution Approach 1:
The invention establishes specific electrical parameter ranges for selecting LED chips (forward voltage Vf within 0.1V of each other, and luminous flux gradient dΦ/dTj within specific ranges). By defining these parameter specifications, the manufacturing process becomes more standardized and controllable, reducing the complexity of LED selection and matching while ensuring consistent color temperature shifting performance.
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 enables a programmable variance in color temperature as a function of drive current using a minimal number of components, effectively mimicking the color temperature change of incandescent lamps during dimming without the need for complex control systems, enhancing efficiency and compatibility with existing LED systems.
Implementation Method 1
control circuitry operable to apply variable duty cycle frequency modulated power to the first LED light source
Implementation Method 2
first LED light source having a first color temperature, a second LED light source having a second, lower color temperature
Implementation Method 3
first LED light source having a first color temperature, a second LED light source having a second, lower color temperature connected in parallel with the first LED light source
Data Source
AI summary
A lighting device includes a first LED light source having a first color temperature, a second LED light source having a second, lower color temperature connected in parallel with the first LED light source, and control circuitry operable to apply variable duty cycle frequency modulated power to the first LED light source while continuous power is provided to the second LED light source. A method of operating a lighting device includes providing variable duty cycle frequency modulated power to a first LED light source having a first color temperature, and providing continuous power to a second LED light source having a second, lower color temperature connected in parallel with the first LED light source.