Easy-to-read information on control panels, especially on industrial machines, is not only a question of comfort, but primarily of safety. As part of a community project, research institutes and industrial companies have now developed a transparent keypad whose keys are illuminated by OLEDs and, in so doing, even display changing symbols.

The illuminating transparent keypad made of organic light-emitting diodes (OLED) was developed by the Fraunhofer-Institut für Angewandte Polymerforschung [Fraunhofer Institute for Applied Polymer Research or IAP], in Golm, Germany, in cooperation with the Bremer Hochschule für Künste HfK [Bremen College of Technology for the Arts (HfK)] and TES-Frontdesign GmbH (based in Neuruppin, Germany). As prototypes, they designed a keypad for a coffee machine whose product selection keys are groundbreaking for control panels of large machines used in industrial manufacturing: The new kind of operating panel consists of a flat OLED display and a transparent keypad that lie exactly on top of one another - together they are only two millimeters thick.

Even if the coffee machine is set up in a dark corner, its buttons are easily visible without additional external lighting and all the options can be comfortably selected. Moreover, the symbols on the OLED display can be changed and even become switches. The buttons do not have to be depressed, the function is much more visible via the respective lighting. For example, on the coffee machine, if the "Espresso" button is pressed, the selected button shows a half-full cup instead of an empty one. If a double espresso is selected by pressing the button two times, a completely filled cup lights up.

The finesse of this new development lies in the position accuracy because only if both films are accurately superimposed does the button pressed by the user initiate the desired action. Another challenge is the rigid OLED material. If the user presses a button, the finger press can be too equally distributed on the below-lying keypad, which, under certain circumstances, makes it respond incorrectly. In order to counteract this, the developers of this technology installed a rise on the top side of the control panel. This focuses the pressure on the button and ensures it functions correctly.

The illuminating transparent keypad should soon make the leap from prototype development to industrial application. The development project was sponsored by the Investitions- und Landesbank Brandenburg [Investment and Regional Bank of Brandenburg] through the future agency Brandenburg Neuruppin.