Riot of color in compact package for large video screens

SUNNYVALE, USA: OSRAM Opto Semiconductors has developed the smallest member of the RGB Multi ChipLED family to bring a new dimension of high-definition picture quality to large full-color video screens.

The Multi ChipLED enables high-resolution full-color video screens –- for example, in television studios, modern conference rooms, trade fairs and concert halls –- to offer brilliant colors and high contrast from all viewing angles. The tiny dimensions of this Multi ChipLED allow a very large number of pixels to be accommodated in a small display area. Housed in a black package that is mostly impervious to ambient light, the LED emits light in brilliant colors with excellent contrast.

OSRAM’s RGB Multi ChipLEDs are housed in a miniature package with dimensions of only 1.6 mm x 1.6 mm and measure just 0.9 mm high. With the RGB Multi ChipLED, it is possible to have a pixel spacing of only 2 mm, meaning that a great many pixels can be generated in a very small area. For example, an area of less than 10 m² is sufficient to display pictures in HDTV quality and accommodate more than 2 million pixels. A 2.5 x 4.0 m (98” x 157”) display 10 m (394”) in diagonal can achieve a system luminance of 1500-2500 cd/m², corresponding to around ten times the luminance of a conventional LED-backlit TFT LCD screen.

Perfect color mixing takes place in the Multi ChipLED package itself thanks to the specially developed encapsulation material. Color appearance remains constant across the entire viewing angle, and the picture appears vibrant even when viewed off-axis. The beam angle of the LED is +/- 60°. Ambient light cannot ruin the picture quality because it is barely reflected at all by the black package in which the LED is housed.

Inside the Multi ChipLED, there is a red chip, blue chip and a green chip fabricated using OSRAM’s ThinFilm and ThinGaN technology. If the RGB-LED is operated with a current of 20 mA, the individual chips produce typical luminous intensities of 250 mcd (red), 350 mcd (green) and 70 mcd (blue). The typical efficiency of this luminous intensity is 4 cd/W, which corresponds to a luminous efficacy of 12 lm/W.