Electroluminescent lighting is widely used as backlighting in a variety of panels, such as aircraft cockpit readouts, automotive gauges, computer controlled thermostats and, of course, liquid crystal display panels in everything from wristwatches to e-reader devices.
But one drawback of conventional electroluminescent panels is that they can only be bent up to a certain degree and so can are applied mostly on flat surfaces. A novel new process developed at Karlsruhe Institute of Technology (KIT) is said to allow for direct printing of electroluminescent layers onto three-dimensional components.
Why Would You Want To Do That?
Well, electroluminescent light (EL) is non directional, and unlike LEDs, filament bulbs, or neon lighting, the brightness of the surface appears the same from all angles of view.
For starters, convex and concave surfaces of various materials, such as paper or plastic, could be made to glow. That means EL objects might be used to provide safety in buildings in case of power failures, for example, glowing doorknobs or backup power switches or safety strips indicating the presence of round support columns.
And think what a creative designer could do with residential interiors having curved walls.
Currently, to fabricate EL panels, the luminescent material is placed between two plastic layers in EL carrier foils. With the new printing process though, the electroluminescent layers are printed directly onto the object without any intermediate carrier.
The multiple components of the coating, which include the electroluminescent and electrically conductive materials, are applied by a unique pad printing process. The pad printing machine has an elastic rubber pad that is easily deformable and ideal for coating curved surfaces. Engineer Elodie Chardin, who worked on the research project, says:
“In this way, it is possible to provide surfaces and even spheres with homogeneous coatings at low costs.”
Eexecutive engineer of industry partner Franz Binder GmbH & Co., Elisabeth Warsitz, adds:
“Homogeneity of the coating of about one tenth of a millimeter in thickness was one of the challenges of this project.”
The KIT/Binder EL process consists of only a few production steps. This saves saves time, money and resources. Also a wide range colors may be
applied, even to the same surface, rather than just the pale green or blue we are all used to seeing.
Photo: Bent and flexible surfaces of various materials, such as paper and plastic, can be provided with a coating to make them glow. (Photo: S. Walter/Binder Group)