On October 10, 2008, OSRAM announced its Advanced Power TopLED Plus and the company claims is the brightest colored LED in its class. The Advanced Power TopLED Plus, which I’ll refer to as just APTP, provides 15% more light for direct display backlighting. The wavelengths associated with each of the primary colored LED is as follows: red (623nm), green (527nm), blue (457nm). The RGB LEDs provide a color gamut of more than 125% NTSC. Although suitable for all direct backlight applications, APTP is best suited for 24″ and larger LCDs.
How does OSRAM achieve better brightness for the APTP? The answer is a special lens designed for backlighting. The lens ensures an “absolutely uniform display backlighting”. I guess we won’t need to worry about brightness uniformity issues on LCDs that use the APTP LEDs from OSRAM. At an operating current of 100 mA the brightness levels achieved by color are as follows: red (14 lm), green (24 lm), blue (28 mW/sr). What is mW/sr? It is milliwatts per steradian. A steradian is a solid angle (cone shaped volume) of measure in 3 dimensions based on a sphere. For example, there are 2*pi radians in a circle and there are 4*pi steradians in one sphere. Blue LEDs are generally difficult to bring about high levels of brightness and that is probably why mW/sr was used instead of lm (lumens). 1200 APTP LEDs are sufficient for 46″ LCDs. With regular LEDs a 46″ LCD will require 1800 to achieve the same level of brightness. You can find more information about the APTP here.
[tags]OSRAM, OSRAM Advanced Power TopLED Plus, Advanced Power TopLED Plus, RGB LED, Backlight, RGB LED Backlight, LED Backlight, LED[/tags]