New brightness records in OSRAM laboratories
Peak values for red high-current chips
Higher current handling capacity gives this chip prototype of the next generation a boost in brightness.
Brightness values of over 300 lm have been achieved by OSRAM Opto Semiconductors with a red 1 mm² chip featuring the latest InGAlP thin-film technology. 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 extremely efficient and can achieve much higher system outputs in projectors with optimum 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.
Green chips set to break records
The new green chip in ThinGaN technology from OSRAM Opto Semiconductors has achieved a brightness in the laboratory in excess of 180 lm. The 1 mm² chips will be used in DRAGON and OSTAR LEDs. Specially designed for low current, these high-power LEDs are efficient light sources for display backlighting.
The high-intensity green chips are destined for LCD backlighting applications. They achieve maximum efficiency in the current range from 100 to 350mA. A smaller number of LEDs is therefore needed to provide a specified brightness level over large display diagonals. Thanks to their small power consumption of slightly more than one watt, LEDs with the new chips place very modest demands on display cooling.
In the laboratory the green chip with a wavelength of 527 nm has achieved more than 180 lm from an operating current of 1 A. From 350 mA it produces 100 lm and consumes 1.4 W (72 lm/W). By contrast, the conventional generation of chips in the current green Platinum DRAGON LED would need an operating current of 1 A to produce 100 lm.
This increase in output is based on a new epitaxial process and improved chip design.
OSRAM expects the first light emitting diodes based on these chips to go into series production by the middle of 2008.
A new epitaxial process and improved chip design have given the next generation a major boost in efficiency.
