Fast data programming TFT pixel threshold voltage compensation circuit with improved compensation accuracy

A method of operating a pixel circuit for a display device comprising the steps of:

• providing the pixel circuit comprising:
• a drive transistor configured to control an amount of current to a light-emitting device during an emission phase depending upon a voltage applied to a gate of the drive transistor, the drive transistor having a first terminal and a second terminal with the second terminal being connected to a first voltage supply line;
• a programming capacitor having a first plate connected to the first terminal of the drive transistor, and a second plate that is electrically connectable to the gate of the drive transistor;
• a storage capacitor having a first plate connected to the first terminal of the drive transistor and a second plate connected to the gate of the drive transistor;
• the light-emitting device having a first terminal that is electrically connectable to the first terminal of the drive transistor, and a second terminal connected to a second voltage supply line;
• and
• a first switch transistor connected between the gate of the drive transistor and the first voltage supply line;
• performing a combined data programming and threshold compensation phase to program data and to compensate a portion of a threshold voltage of the drive transistor comprising steps of:
• placing the first switch transistor in an on state, thereby diode connecting the drive transistor by electrically connecting the gate and the second terminal of the drive transistor through the first switch transistor;
• electrically disconnecting the first terminal of the drive transistor from the first terminal of the light-emitting device;
• and
• electrically connecting the second plate of the programming capacitor to a data voltage supply line that supplies a data voltage, wherein the programming capacitor stores the data voltage and the portion of the threshold voltage of the drive transistor;
• performing a prolonged threshold compensation phase to further compensate the threshold voltage of the drive transistor comprising maintaining the first switch transistor in the on state such that the drive transistor remains diode connected, wherein the storage capacitor stores the threshold voltage of the drive transistor;
• and
• performing an emission phase during which light is emitted from the light-emitting device comprising electrically connecting the first terminal of the light-emitting device to the first terminal of the drive transistor and applying a driving voltage from the first voltage supply line to the light-emitting device through the drive transistor.