Fraunhofer IPMS shows the worldwide first interactive touch controlled flat light source. Based on the fact that OLED is a cold light source, touching control is a safe operation.

Due to the OLED construction, the implementation of an integrated interactive touch interface is possible in a simple way, an additional unique feature of OLEDs. This allows the realization of novel interactive lighting and signage devices without the use of additional hardware like touch foils which reduces the overall efficacy.

TouchOLED operation principle

To achieve the touch function, the ground transparent electrode is used as sensing electrode for capacitance sensing. A touch sensing electronic connected to the electrode, charges this sensing electrode to a known potential. The resulting charge is transferred into a measurement circuit. Placing a finger on the touch surface introduces external capacitance that affects the flow of charge at that point, this registers as a touch. To use in parallel
the OLED for lighting, the operation is subdivided in a touch sensing phase and a lighting operation phase. Based on a high frequency change of phases of 60 Hz and above the user will not recognize the touch sensing (off-state) phase.

Multi-touch signage applications could be realized by the integration of several sensing channels.
Due to the operation principle no technology modification for the OLED is necessary, every OLED could be used for touch operation.