Mobile Phone Projector

Mobile Phone Projector

Global developments at enterprises and academic research institutes are soon expected to result in the next-generation pocket sized digital video projectors and miniature projection displays that could well be incorporated into handheld devices such as mobile phones, PDAs and laptops. The projected image will be approximately the size of a laptop screen. This addition to cell phones improve the experience of watching video-clips and pictures. A mobile phone projector called PicoP has been developed by US-based enterprise Microvision.

The system consists of semiconductor lasers with a tiny mirror and is small enough to fit into a mobile phone or an iPod. Cell phone manufacturers such as Nokia are looking to integrate such projectors into their mobile phones.

Lasers and mirrors

PicoP has two main parts—a set of red, blue, and green lasers and a one millimetre mirror across the lasers. The mirror tilts itself on two axes followed by lasers shining on the mirror. The mirror then reflects the pixel of light on to a plain projection surface.

When all three lasers emit light at the highest intensity, white pixels are produced. Black pixels are produced when the lasers are off. The intensities of the laser beams change to produce different colours.

The lasers flash on the mirror to produce two axes to initiate flickering. This, in turn, results in the production of 30 million pixels per second. Each pixel can illuminate a surface for about 20 nanoseconds. Using this laser and single-mirror set-up, the projector paints a scene onto a surface one pixel at a time. The projection is executed at such high speeds that the human eye perceives only a static image or a continuous movie.

Projector varsity

The Fraunhofer Institute for Silicon Technology in Germany is working on a similar project where a digital projector is being developed that will be small enough to be incorporated into a mobile phone.

The institute has already built a functioning prototype, which is based on a laser beam flashed at a tilting micro-mirror [Editor's Note: See MVIS + Fraunhofer PR from October 2006]. The picture produced has a resolution of 320 x 240 pixels and it renders the image line by line at high speed. However, this prototype is currently too heavy and large to fit inside a cell phone.

The system only projects red light as the existing technology enables only red laser light to be bright enough for the purpose. This could be mass-produced on a microchip. The microprocessor constantly monitors the projection and makes corrections with a backup laser in case of errors such as the projector moving or vibrating.

It's all in the phone

A laboratory model from Siemens features a built-in projector system within a cell phone. The system enables the projection of a complete keypad or display onto a surface. A special pen assists users to write on a virtual keypad and operate the phone’s functions.

The light–source for the cell phone is a tiny semiconductor laser that emits monochrome light to project a real-time image of the display. Siemens plans to further develop this technology and launch a mobile phone equipped with this system in coming months.

— Dominic K