Patent ID: 7656370

Claim:
Method for the ageing compensation of an organic light-emitting diode (OLED) which is fed from a supply voltage and is switched by means of a driver transistor operated in saturation operation, by means of a driving of the light-emitting diode, the method comprising the following steps of: storing at least one desired current-voltage value pair of a desired current-voltage characteristic curve of the light-emitting diode, transferring the driver transistor from saturation operation to linear operation during a measurement cycle, measuring a current value for the current through the light-emitting diode by means of a current measuring circuit in the measurement cycle, determining at least one present current-voltage value pair of a present current-voltage characteristic curve of the light-emitting diode by means of the measured current value, comparing the at least one present current-voltage value pair of the light-emitting diode with the desired current-voltage value pair of the light-emitting diode, generating driving parameters for driving the light-emitting diode in a manner dependent on the result of the comparison, characterized in that the ageing compensation is implemented in a display having a multiplicity of display elements which are formed by a circuit, comprising an OLED, driver transistor, and driving transistor wherein a supply voltage V DD is reduced to an extent such that the driver transistors of the plurality of light-emitting diodes are transferred from saturation operation to linear operation, wherein all of the plurality of light-emitting diodes are switched off before one of the plurality of light-emitting diodes which is to be measured is switched on and for an associated driver transistor of the light-emitting diode which is to be measured the source-drain current I Donlinear through the display supply line is measured, the source-drain voltage of the associated driver transistor for the light-emitting diode which is to be measured is determined by means of the characteristic curve of the associated driver transistor, the gate voltage and the measured source-drain current, a forward voltage value for the light-emitting diode which is to be measured is calculated from the difference between the supply voltage and the calculated source-drain voltage, and a characteristic curve alteration is determined from the comparison of the desired current-voltage value pair with the present current-voltage value pair for the light-emitting diode which is to be measured.