A digitizer tablet (10) having an array of conductors that define a sensing plane (12) for sensing an electromagnetic signal generated by a pointing device (16) disposed external to the plane. The tablet includes circuitry, coupled to the array of conductors, for determining a magnitude of an electrical...http://www.google.com/patents/US5136125?utm_source=gb-gplus-sharePatent US5136125 - Sensor grid for an electromagnetic digitizer tablet
