Pixel circuit, display device, and inspection method

摘要

Compensate for the variations of threshold voltage of a driving transistor. During the period of the reference signal voltage Vref being set to the signal line DTC, voltage between the gate and source of the driving transistor 10C is made equal to or greater than the threshold voltage of the driving transistor 10C, and the difference in voltage of the reference signal voltage Vref and the reference power supply voltage Vref_r is charged to the retentive capacitance 10B. At the same time, the voltage of the source of the said driving transistor 10C is set to the reference power supply voltage Vref_r to make the voltage applied to the light emitting element 10E equal to or lower than its threshold voltage, a voltage corresponding to the threshold voltage of the driving transistor 10C is held in the retentive capacitance 10B. During a period of time when a display signal voltage is set to the signal line DTC, the sampling transistor 10A is conducting, so as to sample the signal voltage, and this signal voltage is superposed on the threshold voltage held in the retentive capacitance.

主权项

1. A pixel circuit comprising:
a sampling transistor having a gate electrode controlled by a first scanning line and a second electrode connected to a signal line; a driving transistor having a gate electrode connected to a third electrode of the sampling transistor and a drain electrode connected to a first power supply line; a light emitting element connected between a source electrode of the driving transistor and a second power supply line and driven by current supplied from the driving transistor; a storage capacitor connected between the gate and source electrodes of the driving transistor; and a switching transistor having a gate electrode controlled by a second scanning line, a second electrode connected to the source electrode of the driving transistor, and a third electrode connected to a reference potential line; wherein the pixel circuit is operable in a first phase with (i) the switching transistor switched on, so that the voltage applied across the light emitting element is less than or equal to a threshold voltage of the light emitting element, (ii) a reference signal voltage applied on the signal line, and (iii) the sampling transistor switched on, so that the voltage applied across the storage capacitor is greater than or equal to a threshold voltage of the driving transistor;the pixel circuit is operable in a second phase with (i) the switching transistor switched off, (ii) the reference signal voltage applied on the signal line, and (iii) the sampling transistor switched on, whereby current through the driving transistor changes the voltage of the source electrode of the driving transistor, whereby the voltage applied across the storage capacitor approaches the threshold voltage of the driving transistor, while the voltage applied across the light emitting element is less than or equal to the threshold voltage of the light emitting element;
the pixel circuit is operable in a third phase with (i) the switching transistor switched off, (ii) a display signal voltage applied on the signal line, and (iii) the sampling transistor switched on, whereby the display signal voltage is superimposed on a voltage applied across the storage capacitor prior to commencement of the third phase; and wherein the reference potential line is connected to a test point that is operable to connect to a probe for measuring current through the driving transistor prior to formation of the light emitting element.