Time for a coffee - yet on large coffee makers, it is hard to tell which button to press for cappuccino or espresso unless they are illuminated. And once the drink has been selected, usually only a tiny LED reveals whether the appropriate button on the machine has been pressed hard enough and the desired coffee drink is about to bubble into the cup.
In a joint project with colleagues at the Potsdam University of Applied Sciences, the University of the Arts HfK in Bremen and the Neuruppin-based company TES-Frontdesign GmbH, scientists at the Fraunhofer Institute for Applied Polymer Research IAP in Golm have developed a keypad based on organic light-emitting diodes, (OLEDs). The really striking feature is that the illuminated symbol can change and is itself the switch. In other words, the buttons do not need captions, the function can easily be recognized by the respective illumination. If the "espresso" button has been selected on a coffee dispenser, for instance, the selected button will indicate a half-filled cup instead of an empty cup.