Handwriting input system based on ultrasonic transducers

A handwriting input system was developed using three collinear ultrasonic transducers. These collinear polyvinylidene fluoride (PVDF) transducers were specially designed for the handwriting input system to give a large writeable area with writing in any direction. Driver and detection circuits were developed for the handwriting system. This handwriting input system based on 2-dimensional position tracing has large writeable area (A4 paper), low drive voltage (5 V), and is independent of the handwriting pad or the pen. © 2011 Tsinghua University Press.