A new mini projector prototype could see mobile phone users hosting impromptu movie screenings on makeshift screens such as white towels or walls... without killing the battery. Unlike conventional projectors the prototype doesn’t need an additional illumination system. Instead it relies on a lens system to project images produced by an OLED onto a wall or other flat surface.

Operating without an extra light source offers the dual benefits of reduced size and energy requirements. The prototype is 2.5 cm long, has a diameter of 1.8 cm and needs very little energy. This means the projector could be easily integrated into a mobile phone or PDA without overtaxing the devices’ battery.

Currently the prototype’s OLED display produces a monochrome image with a brightness of 10,000 candelas per square meter, and color images about half that level. By way of comparison, a computer monitor generates about 150-300 candelas per square meter.

The lenses used in the prototype are made of glass, but the development team is working on an optical system that uses plastic lenses. This is because plastic lenses can be embossed, so they can be produced in larger quantities more simply and cheaply than glass lenses.

The mini projector was developed by research scientists at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena in cooperation with their partners in the EU project HYPOLED.