LED Driver Control Using Dynamic Current Amplitude Selection
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Solution Overview
Problem
Existing methods for controlling the brightness and color of LED lighting systems using pulse-width modulation (PWM) are inefficient, as they often operate at a single current level, leading to wasted power and color shifts when multiple current amplitudes are used, especially in systems with multiple colored LEDs.
Innovation Solution
A method that determines drive values for LEDs by calculating luminous flux weight ratios and selecting appropriate drive currents and duty cycles to maintain desired brightness and color, while minimizing current levels and avoiding color shifts, using a combination of current sources and sensors for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PWM is used to control LED brightness, then brightness control is achieved, but the LED operates at a single current level which is inefficient and wastes power
Solution Approach 1:
The patent implements multiple current amplitude levels (first current amplitude and second current amplitude) that can be dynamically selected based on the desired brightness level. This dynamic current level selection allows the system to operate at optimal efficiency points while maintaining flexible brightness control capability.
Solution Approach 2:
The system changes the current amplitude parameter from a single fixed level to multiple selectable levels. By selecting between different current amplitudes and adjusting duty cycles accordingly, the system achieves both power efficiency and brightness control.
2Use of energy by moving object
If multiple current amplitudes are used to improve efficiency, then power efficiency improves, but color shifts occur in multi-colored LED systems
Solution Approach 1:
The patent applies different current amplitudes to different colored LEDs (red, green, blue) based on their individual efficiency characteristics. Each LED type receives an optimized current amplitude that maximizes its efficiency while maintaining color consistency through separate optimization for each color channel.
Solution Approach 2:
The system independently adjusts current amplitude parameters for each LED color type. By changing the current amplitude parameter specifically for each color based on its efficiency curve, the system maintains both power efficiency and color consistency without cross-interference.
3Illumination intensity
If LEDs are driven at higher current levels to increase brightness, then brightness output increases, but efficiency decreases and lifespan is reduced
Solution Approach 1:
The system dynamically selects between multiple current amplitude levels based on the required brightness output. For lower brightness requirements, the system uses lower current amplitudes that operate at peak efficiency points, while reserving higher current amplitudes only when maximum brightness is needed, thus maintaining optimal efficiency across varying brightness levels.
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 allows for efficient brightness and color control in LED lighting systems, reducing power waste and prolonging LED lifespan by operating at optimal current levels, while minimizing computational complexity and maintaining color accuracy.
Implementation Method 1
a plurality of light emitting diodes (LEDs) of at least two different colors
Implementation Method 2
light emitting diodes (LEDs)
Data Source
AI summary
The present invention relates to a method for determining drive values for driving a lighting device at a desired brightness and color. The method comprising the steps of determining a first luminous flux weight ratio based on the desired color and a first drive current for driving each of the differently colored LEDs, determining a first luminous flux for each of the differently colored LEDs based on the desired brightness and the first luminous flux weight ratio, comparing, for each of the differently colored LEDs, the first luminous flux with a nominal luminous flux for a plurality of different drive currents, selecting, for each of the differently colored LEDs, a preferred drive current that at least can produce the first luminous flux, determining a second luminous flux weight ratio based on the desired color and the selected drive currents for each of the differently colored LEDs, determining a second luminous flux for each of the differently colored LEDs based on the desired brightness and the second luminous flux weight ratio, and determining a duty cycle for each of the differently colored LEDs at the selected drive currents, wherein the selected currents at the determined duty cycles produces the second luminous flux for each of the differently colored LEDs. The present invention provides for the possibility to limit the number of necessary computational steps for determining preferred drive currents. Furthermore, an increase in number of current level and/or differently colored LEDs would only slightly increase the computational cost.