LEDs ♦ news digest
Thanks to the product design the projectors offer very high luminous flux from the available chip surface.
Between 1000 and 8300 lumen can be produced depending on the colour and the LED version. An antireflex coated glass cover instead of the usual lens, together with external optics, ensures that the light is very well bundled.
The new LEDs are therefore ideally matched to the efficient lighting from various additional optics.
“This really opens up the use of LED projectors in offices and classrooms.”
New LEDs with high luminance
Osram Ostar Projection enables light to be routed as efficiently as possible through the optical system which is restricted by the etendue. The etendue of the LEDs is retained and, in conjunction with external optics, produces an extremely narrow beam of light.
Etendue describes the relationship between the emitting light surface and the projected light surface.
To keep the thermal resistance and therefore the temperature rise at the LEDs at an extremely low level the chips are placed directly on a copper plate and not in a classic LED package. They are screwed down to improve the connection with the heat sink.
Details of the product are tabulated below.
Osram Opto projection product
The two new light emitting diodes offer so much luminous flux that they can be used in office projectors with brightness levels of up to 1700 lumen. At the heart of the product is a 2 mm² LED high-current chip based on state-of-the-art thin-film and UX:3 technologies.
The two LED versions contain two (P1W) or four chips (P2W) with a total luminous area of 4 mm² and 8 mm² respectively.
In LED projectors three LEDs in the colours red, green and blue serve as the light source. The LEDs are pulsed one after the other (colour sequential mode), making the colour filter wheel used in classic lamp projectors superfluous. The high output of the new LEDs comes from the latest chip technologies and Osram C² conversion technology for a particularly efficient green. The P2W version emits light pulses
with brightnesses of 1000, 2500 and 8300 lumen for Blue, Red and Green. These high brightness levels require current pulses of up to 32 amps (8 amps per chip) and optimised product design to efficiently remove the resulting heat.
“To apply this high current the four high-power chips of the P2 are connected in parallel. Only then do the new Ostar Projection LEDs generate their maximum brightness from the chips and turn into real power packs for large imagers”, said Stefan Morgott, responsible for Projector Applications at Osram Opto Semiconductors.
Soitec, a developer of semiconductor materials for the electronics and energy industries, and CEA-Leti have renewed their long-standing and fruitful partnership for the next five years.
January / February 2014
www.compoundsemiconductor.net 85
Soitec and CEA unite in five year R&D deal
The partnership focuses on advanced engineered substrates and materials for LEDs and solar cells
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