“There are roughly one gazillion iPad styluses out there and – despite their stylistic differences – they all work in the same way: by mimicking your meaty fingers,” Charlie Sorrel reports for Wired. “What they all lack, and what would make them a lot more accurate, is an on-screen indicator showing where your lines will be drawn.”
“iPen fixes this, taking a similar approach to Wacom’s Inkling accessory, only for the iPad instead of for paper,” Sorrel reports. “The kit consists of two parts: the pen and the digitizer. The digitizer slots into the iPad’s 30-pin dock port, from where it listens for infrared and ultrasonic signals from the pen itself.”
Sorrel reports, “Thus, after a simple calibration (touching the iPen onto the screen), the pen knows exactly where it is. This translates to way more accurate drawing.”
More infer and video in the full article here.