DISPLAY PANEL
An EL light-emitting element is driven digitally to reduce power consumption using a pixel having three transistors and two capacitors. A reset transistor for diode connection writes the threshold voltage of the drive transistor onto a coupling capacitor. The data voltage plus threshold voltage is then written onto the gate of the drive transistor. This reduces the amplitude of the data voltage required, further reducing power consumption.
1 . A display pixel, comprising:
(a) a coupling capacitor having a first terminal connected to a data line;
(b) a selection transistor having a first terminal connected to a second terminal of the coupling capacitor, and a gate connected to a selection line;
(c) a driving transistor having a gate connected to a second terminal of the selection transistor, wherein the driving transistor supplies a current in accordance with a gate potential;
(d) a light emitting element connected to a second terminal of the driving transistor and emitting light as a result of an electric current supplied by the driving transistor;
(e) a reset transistor having a first terminal connected to the second terminal of the driving transistor; a second terminal connected to the first terminal of the selection transistor; and a gate connected to a reset line; and
(f) a storage capacitor connected to the gate of the driving transistor.
2 . A method for supplying current to a light-emitting element in a display pixel, comprising:
(a) providing a data line, a selection line and a reset line;
(b) providing the display pixel having:
(i) a coupling capacitor having a first terminal connected to the data line;
(ii) a selection transistor having a first terminal connected to a second terminal of the coupling capacitor, and a gate connected to the selection line;
(iii) a driving transistor having a gate connected to a second terminal of the selection transistor, wherein the driving transistor supplies a current in accordance with a gate potential;
(iv) the light-emitting element connected to a second terminal of the driving transistor and emitting light as a result of an electric current supplied by the driving transistor;
(v) a reset transistor having a first terminal connected to the second terminal of the driving transistor; a second terminal connected to the first terminal of the selection transistor; and a gate connected to the reset line; and
(vi) a storage capacitor connected to the gate of the driving transistor for storing the gate potential;
(c) providing a data driver for providing a data signal to the data line;
(d) providing a gate and reset driver for providing respective voltages to the selection line and the reset line;
(e) performing in order the following steps:
(i) providing a pre-charge potential on the data line;
(ii) turning on the selection transistor and the reset transistor to write a reset potential into the coupling capacitor;
(iii) turning off the selection transistor and the reset transistor;
(iv) providing a data potential on the data line; and
(v) turning on the selection transistor to write the gate potential corresponding to the reset potential and the data potential into the storage capacitor, whereby the driving transistor supplies current to the light-emitting element.
3 . The method of claim 2 , further including:
(f) performing in order the following steps:
(i) turning off the selection transistor;
(ii) providing a selected potential on the data line;
(iii) turning on the reset transistor to write a first potential of the light-emitting element into the coupling capacitor;
(iv) turning off the reset transistor;
(v) turning on the selection transistor to write the first potential into the storage capacitor, whereby the drive transistor is inverted between an ON state and an OFF state.