Patent ID: 8552948

Claim:
A display device comprising: a pixel comprising a first transistor; an output circuit comprising a second transistor, one of a source and a drain of the second transistor is electrically connected to a gate of the first transistor through a scan line; a power supply control circuit configured to apply one of a first voltage and a second voltage to a gate of the second transistor, and a threshold control circuit configured to control the power supply control circuit, wherein the other of the source and the drain of the second transistor is electrically and directly connected to a wiring supplied with a third voltage, wherein the third voltage is higher than the first voltage and lower than the second voltage, and wherein the threshold control circuit includes a measurement circuit configured to measure first time during which the second voltage is applied to the gate of the second transistor so that a forward bias voltage is applied to the second transistor, and an arithmetic circuit configured to calculate second time during which the first voltage is applied to the gate of the second transistor using the first time so that a reverse bias voltage is applied to the second transistor, wherein a threshold voltage of the second transistor shifts in a reverse direction by applying the reverse bias voltage, and wherein the reverse direction is opposite to a positive direction in which the threshold voltage of the second transistor shifts by applying the forward bias voltage.