As the solid-state lighting market continues to mature, the inherent possibilities of the technology, such as the ability to fine-tune the color of area lighting, become useful factors in designing and living with advanced lighting systems. In a recent article, the Lighting Controls Association’s Craig DiLouie took a detailed look at the critical role played by dimming controls in making the best use of color-tunable LED lighting, particularly blends of color temperatures in white lighting.
“Mixing color LEDs can generate millions of colors, including white, simply by mixing red, green and blue LEDs in varying degrees of relative intensities via dimming. However, RGB mixing can result in gaps between each discrete color, resulting in errors in white light color accuracy. By mixing colors and white, a wider range of whites and near-white colors can be achieved with greater fidelity and depth. Another approach is to mix cool- and warm-white LEDs, which provides a range of white light shades selectable between these two points.
“Again, the key to adjusting color is raising or lowering the relative intensity of the source’s color components via dimming.”
Providing user-adjustable control to lighting systems that use mixed-color LEDs requires sophisticated microprocessor-based controls with optical feedback loops and in some cases preset color blends are stored and recalled by the systems allowing the system to adjust for consistent light color as the luminaires color shift over time.
“Luminaires that use mixed-color LEDs require sophisticated control and individual drivers for each color to maintain the set color temperature as LEDs age and ambient temperatures fluctuate,” DiLouie adds. “Through the use of continuous closed-loop optical feedback, the balance of RGB output can be balanced to maintain the specified color mix, thereby increasing color consistency and stability.”
Read the full article: White-Tunable LED Lighting
