Osram Opto Semiconductors GmbH of Regensburg, Germany has launched the Ostar Projection Cube grren LED for embedded projection applications in smartphones and cameras.
Osram Opto says that the next development for smart phones and cameras is an integrated miniature projector that can display images on a much larger surface than existing displays (i.e. embedded projection, using LEDs as the light source). However, the greatest challenge so far for lighting technology has been the limited efficiency of the green light-emitting diodes, since high brightness is essential if the projected image is to be seen with ambient light.
Efficient LEDs for red and blue light have been available for some time, but LEDs that produce green light with acceptable luminance have not been available. Osram claims that the Ostar Projection Cube now fills this gap by offering luminous efficiency of 110 lumens per watt (lm/W). This is claimed to be much more than other previously available green LEDs in the embedded projection sector, enabling sufficient output to be achieved in embedded projectors for the first time.
"The new LED almost doubles the brightness in smart-phone applications, so embedded projectors with a system brightness of up to 25 lumens are possible," says Wolfgang Schnabel, marketing manager, Projection, at Osram Opto. The image is hence clearly visible even without dimming and ambient lighting, says the firm. Also, due to the efficiency of LED technology, the projector can also be used in mobile applications with limited battery capacity.
The new green LED is available in two versions, with a 1mm or 0.75mm edge-length chip (providing a solution for all standard imager formats in mobile applications) producing 260 lumens at 700mA and 2.3W or 130 lumens at 350mA and 1.2W, respectively.
Such high luminance from a small surface area is made possible with the aid of encapsulation that sharply defines the light surface so that light is emitted without package reflections. With a footprint of 3.8mm x 4.1mm and a height of only 0.6mm, the new LED enables extremely low-profile projection engines to be designed, suiting modern smart-phones and cameras. Also, the Ostar Projection Cube does not have a glass cover, so external optics can be placed very close to it, maximizing efficiency.
Osram Opto's Francis Nguyen is presenting the new LED on 11 June at the Projection Summit 2012 in Las Vegas during his talk on the 'Evolution of LEDs used in Pico Projectors'.
