Organic LED displays are vulnerable to developing age dependent non-uniformities of emitted light across a display matrix; there is accordingly a need for rapidly and accurately correcting such non-uniformities in an initially calibrated display device. As the decay of emitted light follows an exponential law, change in light output can be predicted by accumulating (i.e. performing numeric integration) the driving current for each individual pixel during an elapsed time; then, based on such predicted change, the driving current can be adjusted for each pixel such to compensate the decay. Another possibility of correcting non-uniformities is also described, by arranging a photodetector, such as a camera, for measuring the light emitted by different single pixels or groups of the same, whose size is made stepwise progressively bigger by adequate displacement of the photodetector along X, Y and Z axis, while correcting unevenesses at every step.

A method and apparatus for calibrating display devices and automatically compensating for loss in their efficiency over time

Circuits for programming, monitoring, and driving pixels in a display are provided. Circuits generally include a driving transistor to drive current through a light emitting device according to programming information which is stored on a storage device, such as a capacitor. One or more switching transistors are generally included to select the circuits for programming, monitoring, and/or emission. Circuits advantageously incorporate emission transistors to selectively couple the gate and source terminals of a driving transistor to allow programming information to be applied to the driving transistor independently of a resistance of a switching transistor.

System and methods for aging compensation in AMOLED displays

A method and system for programming, calibrating and driving a light emitting device display is provided. The system may include extracting a time dependent parameter of a pixel for calibration.

Method and system for programming, calibrating and driving a light emitting device display

Pixel circuit 210 includes a current programming circuit 240 and voltage programming transistors 251 and 252. In order to set the tone of the light emission from the organic EL element 220, the first and second voltage programming transistors 251 and 252 are set to the OFF and ON state, respectively, and voltage programming is carried out using a voltage signal Vout. Next, the states of the first and second voltage programming transistors 251 and 252 are switched, and current programming is carried out using a current signal Iout.

Pixel circuit for light emitting element

A technique for driving a column of pixels that include light emitting elements. The technique incorporates feedback data provided from feedback data sources connected to the data line and to feedback line of the array, pixel driving circuit with feedback path. The technique can also include block of the reference elements for input signal corrections.

Circuit and method for driving an array of light emitting pixels

A constant current driver with auto-clamped pre-charge function includes a reference bias generator and a plurality of constant current driver cells, each being connected to the reference bias generator to form a respective current mirror. Each constant current driver cell has a switch transistor, a current output transistor and a pre-charge transistor. When a constant current is outputted from the current output transistor for driving an organic light emitting diode, the pre-charge transistor is turned on to provide a drain to source current as an additional large current for rapidly pre-charging the organic light emitting diode until the gate to source voltage of the pre-charge transistor is smaller than the threshold voltage.

Dar-Chang Juang

Papers

Constant current driver with auto-clamped pre-charge function