Lamb wave graphic tablet
A graphic sensor based on the measurement of the propagation time of an acoustic wave train is described. Lamb waves are launched in a plate of ordinary glass by piezoelectric bars bonded to the edges of the plate. They are detected at their arrival under the tip of the drawing pencil by a small piezoelectric disc placed in the pencil body. The useful area of the tablet is 19×27 cm2; the resolution is about 0.2 mm.