Abstract: A transistor control circuit (74) comprises a source-gated thin film transistor (70), an input for receiving a drive voltage representing a desired control of the source-gated transistor and a current source (82) for causing a known current to pass through the source-gated transistor (70). A first capacitor (78) stores a resulting gate-source voltage of the source-gated transistor when the known current is passed through the source-gated transistor. The drive voltage is modified using the resulting gate-source voltage, and the modified voltage is used in the control of the source-gated transistor. This control can provide a translational shift in the operating characteristics of the transistor, and it has been found that this can compensate for ageing of the transistor, for non-uniformity between different devices, and for temperature variations.

Abstract: The invention concerns an OLED device with a cathode 1, an anode 2 and an active stack 3, wherein the anode 1 is segmented into a plurality of anode segments 8 each defining an OLED segment 4. Further, a capacitance measuring unit 12 is provided which is arranged for measuring a plurality of capacitance coefficients between two anode segments 8 and/or between an anode segment 8 and surrounding earth, respectively. This way, an OLED device for illumination purposes with a reliable proximity sensing function is achieved.