Whetstone Albert L, Fine Samuel, Banks William, Phillips Stanley C: Graphical data device. Amperex Electronic Corporation, September 24, 1974: US3838212 (40 worldwide citation)

A graphical data device employing a stylus moving over an area to be digitized and utilizing a fast rise time sound energy shock wave, generated by a spark at the location of the stylus and propagated through the air for providing coordinate information as to the instantaneous position of the spark. ...

Whetstone Albert L, Fine Samuel: Magnetic graphical data device. Science Accessories Corporation, March 7, 1972: US3648277 (8 worldwide citation)

A coordinate digitizing device is provided with a localized source of magnetic energy positioned with respect to a wire array, each of said wires terminated in a common delay line. The magnetic energy is pulsed at a desired point, initiating a digitization time interval required for a pulse appearin ...

Location digitizer. Science Accessories, July 24, 1974: GB1361057-A (1 worldwide citation)

1361057 Co-ordinate location digitizer SCIENCE ACCESSORIES CORP 19 July 1971 [21 July 1970] 33715/71 Heading G4H In a graphical data device the position of a stylus 132 on a two-dimensional wire grid 26 is recorded in X, Y counters as the time difference between an initial pulse 30A from a stylus tr ...