Patent ID: 8159422

Claim:
A light emitting display device comprising a pixel having a light emitting device and a drive circuit for driving the light emitting device, the drive circuit comprising: a first thin film transistor and a second thin film transistor having the same polarity, a gate terminal of the first thin film transistor being connected to a gate terminal of the second thin film transistor, a source terminal of the first thin film transistor being connected to a source terminal of the second thin film transistor, and the source terminals of the first thin film transistor and the second thin film transistor being connected to one end of the light emitting device; a first switch having one end connected to the source terminals of the first thin film transistor and the second thin film transistor and to one end of the light emitting device and having the other end connected to a first line; and a capacitor having one end connected to the gate terminals of the first thin film transistor and the second thin film transistor and having the other end connected to the source terminals of the first thin film transistor and the second thin film transistor, wherein the drive circuit has at least a first period for writing a drive signal and a second period for driving the light emitting device after the first period, wherein the first period contains a period in which the first line and the one end of the light emitting device are set to the same voltage through the first switch, and a second line for supplying the drive signal of the light emitting device is electrically connected to a drain terminal of the first thin film transistor and the gate terminals of the first thin film transistor and the second thin film transistor, to supply a current to the first thin film transistor from the second line, wherein the second period contains a period in which connection between the second line and the first thin film transistor, connection between the second line and the second thin film transistor, and the first switch are shut off, and wherein the capacitor has a capacitance value which is three times or more as large as a total capacitance value obtained by adding a channel capacitance and a gate and drain overlap capacitance of the first thin film transistor and a channel capacitance and a gate and drain overlap capacitance of the second thin film transistor.