Each unit consists of four LED packages (two green, one blue and one red) in a lozenge-shaped arrangement. All the chips are manufactured in Osram's thin-film technology and have a correspondingly high luminous efficacy.
Any number of these lozenge-shaped packages can be combined, either offset or in rows, to form scalable high-intensity backlighting systems.
Osram Opto has adapted its Argus lens system, which is familiar from radial LEDs, and applied it to surface-mount LEDs such as the Golden Dragon Argus. The lenses spread the light over a wide area, so instead of a con-centrated beam of light shining upwards it is emitted sideways over the surface.
The company says that backlighting systems based on the Golden Dragon Argus 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 (CCFLs) 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, these LEDs and lenses are much smaller than comparable systems, enabling very low-profile LCD displays.
With switching times of less than 100 ns, the devices are 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, but also allows the light sources to be faded to any brightness level.
Displays backlit with LEDs do not require active cooling, even at high outputs. They 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.
