Osram Opto Semiconductors has revealed the first LED to achieve
more than 1000 lumen - brighter than a 50W halogen lamp, claimed
the firm.
“We can achieve this and repeat it. This is not an R&D special.
The ‘heroes’ are 10 per cent higher,” Volker Haerle, marketing head
at Osram, told EW. “And there was no special 25°C thermal
set-up. The junction was at a representative temperature.”
Light emitting diodes (LEDs) have been used in electronic systems
for many years. There is nothing new about the use of LEDs as panel
display lights or even in optical fibre communications.
But
the use of higher power LEDs as general purpose lighting
sources, which have the potential to replace filament bulbs and
even fluorescent tubes, has now become one of the most interesting
component markets in the industry.
The device, part of Osram’s Ostar family, has the same footprint as
Lumileds’ Star devices and has six 1mm sq. white LED die.
“What this means in actual practice is that a single device with a
38 degree reflector is all that is needed to illuminate a desk with
more than 500 lux from a height of two metres,” said Osram.
The reflector concerned has been designed by Italian optics-maker
Fraen, and also comes in a narrower beam version.
With the relatively low temperatures involved, 120°C maximum
compared with 5,000°C in an incandescent bulb, heat has to be
persuaded to leave any high-power LED-based luminair.
“The heat from this Ostar is in the order of 20W, 40 per cent of
the heat from a halogen,” said Haerle. This equates to 50 lm/W - 75
lm/W is also claimed, at the lower operating current of
350mA.
Even at 20W, a heatsink is required. Osram has been working with
Taiwanese heatsink firm CoolerMaster. “A sink 80x80x80mm would be
suitable for a realistic downlighter application,” said Haerle.
“This size can be reduced if 6mm heatpipes are used to take the
heat away from the immediate vicinity of the LED.”
Lifetime with this heatsinking in this application has been
estimated. “We feel very comfortable with 30,000 hours to half
brightness,” said Haerle. “Lifetime very much depends on operating
conditions.”
Samples should be with customers in May. Market launch is planned
for summer 2007.