Wednesday, August 10, 2011

Color LEDs enable architectural, entertainment, and horticultural applications

While phosphor-converted white LEDs are touted for general-illumination and backlighting applications, colored LEDs can serve in many more applications in architectural, entertainment, horticultural, and other segments. The deep-red LED is the recent addition and targets applications such as horticulture and entertainment.

Deep-red for safety and horticulture

The deep-red LED differs from the standard-red (620-645 nm) offering. The deep-red color is more visible in safety-centric application. The emitter generates 720 mW of radiometric power or radiant flux at 700 mA.

Horticulture could prove to be a major consumer of the deep-red LEDs. It turn out that the 660-nm wavelength corresponds to peak chlorophyll absorption in plants as we covered in an article on LED based horticultural lighting. Plant factories and green houses are moving away from broad-spectrum lights to ones that provide specific wavelengths hoping to induce better plant grow with less energy.

Brighter green LEDs

Green LEDs, meanwhile have been challenged in terms of lumen output due to a physics phenomenon called the charge separation effect.

A green LED that delivers 150 to 160 lm at 350 mA of drive current, could enable advances in general lighting, backlighting, and specialty applications such as horticulture.

Large-screen TV backlights for example can benefit from direct backlighting using clusters of red, green, and blue (RGB) LEDs that improve the color gamut of the picture. But TV makers have gone away from the RGB scheme, in part because they need to combine two green LEDS with each red and blue LED to achieve consistent brightness. Likewise, RGB-based general-lighting fixtures can produce tunable color, but the available green LEDs don't deliver the needed efficiency.

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