Brightness values of over 300 lm have been achieved by OSRAM Opto Semi-conductors with a red 1 mm² chip featuring the latest InGAlP thin-film technol-ogy. The chips are designed primarily for projection applications, bringing a real boost in brightness to this sector. They will be used in Dragon and Ostar LEDs.
The chip prototypes will show their strengths in projection applications, particularly in Ostar Projection. They are more powerful than their predecessors and offer a much greater luminance for the same chip area. Much more light is therefore available for injecting into external optical systems. As a pure surface emitter Ostar LEDs are ex-tremely efficient and can achieve much higher system outputs in projectors with op-timum light injection.
Thanks to thin-film technology the chip surfaces are also scalable. This means that smaller chip surfaces are needed to produce a particular brightness. This is important especially for exterior automobile lighting because the same number of LEDs can be used to achieve greater system brightness.
Under laboratory conditions the red chip with a wavelength of 615 nm achieves more than 300 lm from an operating current of 2 A. With a power consumption of 6 W its efficiency is an impressive 52 lm/W. By comparison, the current red Platinum Dragon LED has an output of 96 lm from a consumption of 2.5 W, giving a luminous efficacy of 38 lm/W. “We have achieved this enormous increase in brightness above all by designing the new chips to handle higher currents. This has resulted from optimizing the series resistors”, said Dr. Ralph Wirth, development engineer at OSRAM Opto Semiconductors.
OSRAM expects the first light emitting diodes based on these chips to go into series production by the middle of 2008.