Siemens developers have built a cell phone in the form of a pen that enables users to actually write text messages or telephone numbers by hand. The prototype of the "PenPhone" will be presented at this year's CeBIT fair in Hanover (until March 24), in Hall 26. The phone's unique feature is made possible by an image-recognition system that converts the movements of the pen into letters and numbers.

The tri-band phone is about the size of a cigar, with a length of 14 centimeters and a diameter of about two centimeters. It is equipped with a small display, a speaker for voice output, and a Bluetooth interface for connecting to a handheld computer or headset. It has not yet been decided if the phone will actually go into production. Studies show that adults, and senior citizens in particular, hardly send any text messages with their cell phones because they find keying in texts to be too bothersome. The PenPhone, on the other hand, is used like a normal pen. The optical recognition system makes it possible to write texts on virtually any type of smooth surface — and without ink, of course. The device’s writing function is activated when a small button at the tip makes contact with a surface. When this happens, a tiny infrared camera begins to record nearly hundred pictures per second as a rough pixel pattern, which changes with every movement of the pen.

The high image-frequency rate enables the system to recognize in real-time the location of the tip in relation to its initial position. The software then uses these coordinates to determine which letters are being written. Unlike certain types of computer organizers, which can only recognize a special type of writing applied to their touchscreen display, the PenPhone makes it possible for users to write as they would with a normal pen. The cell phone display shows each letter (or number) written and also voice outputs the information via the speaker. When the message is finished, it can be sent by issuing a command in the form of pen movements, and telephone numbers can be dialed in a similar manner. Users can also choose to operate the cell phone by using a small button next to the display, or by issuing voice commands. For the latter, the user simply speaks the number into the microphone, after which it appears on the display and is then dialed. (IN 2004.03.5)