With completion of the Super Proton Synchrotron (SPS) fast approaching, CERN needed a way to control the accelerator’s complex systems. Linking individual cables directly to the control room had worked fine for the Proton Synchrotron (PS), but was not economically viable for a machine 10 times its size.
Frank Beck, who later became head of SPS Central Controls, knew the possibilities of existing touch-screen technology, but found their mechanical designs unsuitable. He turned to his colleague Bent Stumpe, who, in a handwritten note dated 11 March 1972, presented his proposed solution – a capacitive touch screen with a fixed number of programmable buttons presented on a display.
It was extremely simple mechanically. 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. A prototype was shown to those in charge of the SPS project, who decided to use the technology. Frank Beck and Bent Stumpe described this touch screen in a 1973 CERN report.
When the SPS started up in 1976 its control room was fully equipped with touch screens. By 1977 the capacitive touch screen was already available commercially and being sold to other institutes and companies worldwide. The original touch screen had only 16 fixed “buttons” associated with distinct areas of the screen, but already in 1977 it was obvious that a more flexible arrangement for dividing up the screen would have many advantages. Stumpe developed his original concept to create an X–Y touch screen, which sensed the position touched via two layers of capacitors corresponding to X and Y co-ordinates. Following prototype work at CERN, development began with NESELCO and the University of Aarhus, supported by the Danish state development funds. Despite the involvement of industry, CERN, as many other research labs at that time, did not yet have the necessary knowledge transfer processes in place to ensure a wide dissemination of Bent’s invention… while today this forms an integral part of how the organization creates tangible benefits for society. At this point, CERN’s involvement with the further development of touch screens came to an end.
Today, the CERN Control Centre no longer uses touch screen to control the accelerators. However, touch-screen technology is ubiquitous in devices such as mobile phones, tablets and computers.