ELEMENT SUBSTRATE AND LIGHT-EMITTING DEVICE
A potential of a gate of a driving transistor is fixed, and the driving transistor is operated in a saturation region, so that a current is supplied thereto anytime. A current control transistor operating in a linear region is disposed serially with the driving transistor, and a video signal for transmitting a signal of emission or non-emission of the pixel is input to a gate of the current control transistor via a switching transistor.
1 . (canceled)
2 . A light-emitting device comprising:
a semiconductor film;
a gate insulating film over the semiconductor film;
a first gate electrode over the gate insulating film;
a second gate electrode over the gate insulating film;
a first insulating film over the first gate electrode and the second gate electrode, the first insulating film comprising a first contact hole and a second contact hole;
a first conductive film over the first insulating film;
a second conductive film over the first insulating film;
a second insulating film over the first conductive film and the second conductive film, the second insulating film comprising a third contact hole; and
a light-emitting element over the second insulating film,
wherein the semiconductor film comprises a first region, a second region, a third region and a fourth region,
wherein the first region is electrically connected to the first conductive film through the first contact hole,
wherein the second region is electrically connected to the second conductive film through the second contact hole,
wherein the second conductive film is electrically connected to the light-emitting element through the third contact hole,
wherein the first gate electrode overlaps an entirety of the third region,
wherein the second gate electrode overlaps entirety of the fourth region,
wherein the third region comprises a winding portion,
wherein a first transistor comprises the third region is configured to operate in a saturation area when the light-emitting element emits light, and
wherein a second transistor comprises the fourth region is configured to operate in a linear area when the light-emitting element emits light.
3 . The light-emitting device according to claim 2 , further comprising a resin over the light-emitting element.
4 . The light-emitting device according to claim 2 ,
wherein a channel length of the first transistor is L 1 ,
wherein a channel width of the first transistor is W 1 ,
wherein a channel length of the second transistor is L 2 ,
wherein a channel width of the second transistor is W 2 , and
wherein when L 1 /W 1 :L 2 /W 2 =X:1, X is greater than 5 and less than 600.
5 . A light-emitting device comprising:
a semiconductor film;
a gate insulating film over the semiconductor film;
a first gate electrode over the gate insulating film;
a second gate electrode over the gate insulating film;
a first insulating film over the first gate electrode and the second gate electrode, the first insulating film comprising a first contact hole and a second contact hole;
a first conductive film over the first insulating film;
a second conductive film over the first insulating film;
a second insulating film over the first conductive film and the second conductive film, the second insulating film comprising a third contact hole; and
a light-emitting element over the second insulating film,
wherein the semiconductor film comprises a first region, a second region, a third region and a fourth region,
wherein the first region is electrically connected to the first conductive film through the first contact hole,
wherein the second region is electrically connected to the second conductive film through the second contact hole,
wherein a power line comprises the first conductive film,
wherein the first conductive film overlaps the first gate electrode and the third region,
wherein the second conductive film is electrically connected to the light-emitting element through the third contact hole,
wherein the first gate electrode overlaps an entirety of the third region,
wherein the second gate electrode overlaps entirety of the fourth region,
wherein the third region comprises a winding portion,
wherein a first transistor comprises the third region is configured to operate in a saturation area when the light-emitting element emits light, and
wherein a second transistor comprises the fourth region is configured to operate in a linear area when the light-emitting element emits light.
6 . The light-emitting device according to claim 5 , further comprising a resin over the light-emitting element.
7 . The light-emitting device according to claim 5 ,
wherein a channel length of the first transistor is L 1 ,
wherein a channel width of the first transistor is W 1 ,
wherein a channel length of the second transistor is L 2 ,
wherein a channel width of the second transistor is W 2 , and
wherein when L 1 /W 1 :L 2 /W 2 =X:1, X is greater than 5 and less than 600.