Mini projector is small enough for cellphones

Paul Boughton
Looking at photos on a cellphone display can be arduous, but researchers are developing a new mini beamer (projector) that is small enough be integrated in a cellphone or a PDA. As it does not need an extra light source, it also conserves the charge in the battery. Projection screens can be improvised from, say, a white beach towel.

The mini projector was developed by research scientists at the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF) in Jena in co-operation with partners in the EU project Hypoled. Unlike conventional beamers it does not need an additional illumination system. Because the beamer can operate without an extra light source it offers a number of advantages: first, it takes up little space, as the prototype is just 25mm long and has a diameter of 18mm; second, the device needs very little energy and therefore does draw much current from the battery in the host device.

Dr Stefan Riehemann, group manager at the IOF, comments: "The key component of the projector is an organic display, or OLED, developed by our colleagues at the Fraunhofer Institute for Photonic Microsystems (IPMS) in Dresden." Currently the OLED display produces a monochrome image with a brightness of 10,000 candelas per square metre; for colour images the brightness is about half that level. In comparison, a computer monitor generates about 150-300 candelas per square metre. A lens system projects the image produced by the OLED onto a wall or other flat surface. The lenses are made of glass but the research scientists are already developing an optical system that uses plastic lenses. As plastic lenses can be embossed, they can be produced in larger quantities more simply and cheaply than glass lenses.

The researchers are exhibiting a monochrome prototype of the mini beamer in Hall B2, Stand B2.421, at the Laser World of Photonics trade show from 15-18 June 2009 in Munich.

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