Since the beginnings of the LED in the early 1960s, its luminous efficacy has been increased more than a thousand-fold: from 0.1 lumen/Watt to nearly 100 lumen/Watt. In comparison, a conventional 100 Watt light bulb – now put on the Index by the EU – achieves an average reading of 15 lumen/Watt, an energy-saving lamp achieves 60.
So it comes as no surprise that since August 2009 the world’s largest illuminated advertisement, the Bayer cross on Leverkusen, has been lit up with to 1,710 “liquid LEDs”, liquid-cooled LED lamps, instead of 40-Watt light bulbs.
The former impressed the Bayer AG engineers with their great energy-saving potential, their long durability (approximately 40,000 hours), the color of the light in the warm white version and the simplicity of integrating them in the lamp sockets already in place by means of a bayonet connector.
The illuminating diodes of the liquid LEDs from the Taiwanese manufacturer Liquileds are not only cooled by the glass balloon filled with white oil, but also shine in an extended angle of 130 degrees, an important prerequisite for being used in an illuminated advertisement that is visible from all sides.
Be it the automotive or electrical industry, light and luminaire manufacturers, or medical and advertising technology: LED has evolved from being just a small space display element to an efficient light source in its own right. LEDs have long since not only featured in displays and have replaced Xenon as the illuminant in spotlights, they are also used for street lighting and increasingly in private households. This has been made possible on the one hand through advances with regard to intensity, and on the color spectrum of the light they produce.
Whereas in recent years the focus was primarily on advancing LED technology, in particular refining the previously very cold, bluish shimmering light and its reach, now, thanks to the rapid development of semi-conductor crystals and their functional depth, the application and design of products is very much at the forefront.
LED guiding lights in sockets, for example, are now standard with most renowned manufacturers: Depending on the respective switch design, an outer light strip projects an indirect, glare-free light sphere downwards. In many cases sockets that have already been fitted can also be equipped. Some LED sockets feature an individually adjustable twilight setting; an integrated light sensor activates the LED and is one of the great advantages of semi-conductors dependent on electricity. These have great potential: As electronic components, LEDs can be altered and controlled.