Method of driving a light emitting device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Mitsuaki Osame, Jun Koyama
Life of this patent
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Abstract
The present invention is characterized in that a transistor with its L/W set to 10 or larger is employed, and that |VDS| of the transistor is set equal to or larger than 1 V and equal to or less than |VGS−Vth|. The transistor is used as a resistor so that the resistance of a light emitting element can be held by the transistor. This slows down an increase in internal resistance of the light emitting element and the resultant current value reduction. Accordingly, a change with time in light emission luminance is reduced and the reliability is improved.
Claims18
A light-emitting device comprising:
- a pixel including a signal line, a scanning line, a light-emitting element, a first transistor, and a second transistor over a substrate,
- wherein one of source and drain of the first transistor is electrically connected to the light-emitting element, a gate of the first transistor is electrically connected to one of source and drain of the second transistor,
- wherein the other of source and drain of the second transistor is electrically connected to the signal line, a gate of the second transistor is electrically connected to the scanning line,
- wherein a semiconductor including a channel of the first transistor has a region extending in a first direction and a region extending in a second direction under the gate of the first transistor, and
- wherein the first direction is not parallel to the second direction.
A light-emitting device comprising:
- a pixel including a signal line, a scanning line, a light-emitting element, a first transistor, and a second transistor over a substrate,
- wherein one of source and drain of the first transistor is electrically connected to the light-emitting element, a gate of the first transistor is electrically connected to one of source and drain of the second transistor,
- wherein the other of source and drain of the second transistor is electrically connected to the signal line, a gate of the second transistor is electrically connected to the scanning line,
- wherein a semiconductor including a channel of the first transistor has a region extending in a first direction and a region extending in a second direction under the gate of the first transistor, and
- wherein the first direction is orthogonal to the second direction.
A light-emitting device comprising:
- a transistor including a gate electrode and a channel in a semiconductor over a substrate,
- wherein the semiconductor including the channel has a region extending in a first direction and a region extending in a second direction under the gate of the transistor, and
- wherein the first direction is not parallel to the second direction.
A light-emitting device comprising:
- a transistor including a gate electrode and a channel in a semiconductor over a substrate,
- wherein the semiconductor including the channel has a region extending in a first direction and a region extending in a second direction under the gate of the transistor, and
- wherein the first direction is orthogonal to the second direction.
Dependencies are inferred from the claim text.