15.12.2005 Overview

Light of impressive uniformity

Golden DRAGON ARGUS

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Golden DRAGON ARGUS LEDs from OSRAM Opto Semiconductors provide uniform backlighting with perfect colour mixing for large display surfaces, thanks to their special lens and high luminous efficacy. Lozenge arrangements comprise four LEDs (two green, one blue and one red). Any number of these lozenges can be combined, either offset or in rows, to form infinitely scalable high-intensity backlighting systems.

OSRAM Opto Semiconductors has taken the ARGUS lens system familiar from radial light emitting diodes and adapted it to SMT LEDs (Surface Mounted Technology) such as the Golden DRAGON ARGUS, thereby transferring its optical properties to this high-output light source. All four LED chips are manufactured in thin-film technology and have a correspondingly high luminous efficacy. The lenses spread the light over a wide area. So instead of a concentrated beam of light shining upwards it is emitted sideways over the surface.

Backlighting systems based on the Golden DRAGON ARGUS therefore achieve uniform distribution of light and an excellent mix of red, green and blue to produce white. The LEDs can be individually controlled to change the colour tone. Compared with conventional cold cathode fluorescence lamps the coverage of the colour triangle increases by more than 50%. Backlighting systems with these LEDs therefore even exceed the standards of the National Television System Committee (NTSC).

With a package height of just 4 mm and optical ARGUS lens properties, the OSRAM solution is much smaller than comparable systems so extremely low-profile LCD displays are possible. Their switching times are less than 100 ns. They are therefore suitable for sequential colouring, a process in which the three basic colours are pulsed at high frequency and in a particular sequence. As the human eye cannot follow such high-speed changes it sees them as full-colour moving pictures of exceptional brilliance. No special colour filters are needed. Pulsing not only ensures the moving pictures are sharp and precise it allows the light sources to be faded to any brightness level.

Displays backlit with OSRAM LEDs do not need active cooling, even at high outputs. Indeed, because of the high efficiency of the system the temperature does not exceed 60°C. In the same way the power consumption for a 32 inch can be reduced by 20% compared to standard CCFL solution to reach 100 W. The LEDs contain no lead or mercury and comply with RoHS guidelines (Restriction on Hazardous Substances). They are also vibration-proof and shockproof and have a life of more than 50,000 hours.