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Tech Primer
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. 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
For more information see:
www.ipms.fraunhofer.de/de/y2006/pr_061011micro.shtml
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