During the year 1976, a new x-y capacative screen, based on the capacitance touch screens developed in 1972 by Danish electronics engineer Bent Stumpe, was developed at CERN. This technology, allowing an exact location of the different touch points, was used to develop a new type of human machine interface (HMI) for the control room of the Super Proton Synchrotron particle accelerator. In a handwritten note dated 11 March 1972, Stumpe presented his proposed solution – a capacitive touch screen with a fixed number of programmable buttons presented on a display. The screen was to consist of a set of capacitors etched into a film of copper on a sheet of glass, each capacitor being constructed so that a nearby flat conductor, such as the surface of a finger, would increase the capacitance by a significant amount. The capacitors were to consist of fine lines etched in copper on a sheet of glass – fine enough (80 μm) and sufficiently far apart (80 μm) to be invisible. In the final device, a simple lacquer coating prevented the fingers from actually touching the capacitors. In the same year, MIT described a keyboard with variable graphics capable of multi-touch detection.