The digital paper is printed with a pattern of dots based on a six by six matrix which has width and height of 1.8mm. The printed dots are positioned above, below, to the left of and to the right of the intersections of the matrix, as shown in the diagram below.

This pattern, printed on ordinary paper by a laserjet printer, enables the digital pen, as its infrared camera traverses a form or notebook, to record its precise location and motion to capture data. The pattern enables the production of 36 million square miles of paper without a repeat, equivalent to 960 trillion sheets of standard sized printing paper.

 

 

The digital pen contains an infrared camera, a processor, memory, a datalink (either USB or Bluetooth for mobile applications where a mobile phone acts as a modem) and a rechargeable battery.

The pen processes images of the pattern 75 times per second while writing in ink on the patterned paper. Perspective, rotation, tilt and error correction is performed for each image. The pen tip position is determined at a resolution of 0.0375 mm. Penstrokes from up to 200 pages of atandard paper text are typically stored in the pen.