Light emitting device
First Claim
1. A light-emitting device including a pixel portion, the pixel portion comprising:
- a first transistor and a second transistor each including a channel formation region, a source, and a drain;
a first insulating film over the channel formation region of the first transistor and the channel formation region of the second transistor;
a first gate electrode over and in contact with the first insulating film, the first gate electrode overlapping with the channel formation region of the first transistor;
a second gate electrode over and in contact with the first insulating film, the second gate electrode overlapping with the channel formation region of the second transistor;
a second insulating film over and in contact with the first gate electrode and the second gate electrode;
a first wiring over and in contact with the second insulating film, the first wiring including a region which overlaps with the second gate electrode, wherein a capacitor comprises the region and the second gate electrode overlapping with the region;
a third insulating film over the first wiring;
a pixel electrode over and in contact with the third insulating film, the pixel electrode being electrically connected to one of the source and the drain of the second transistor; and
a second wiring over and in contact with the third insulating film,wherein the second wiring does not overlap with the region.
1 Assignment
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Accused Products
Abstract
A light emitting device is provided which can prevent a change in gate voltage due to leakage or other causes and at the same time can prevent the aperture ratio from lowering. A capacitor storage is formed from a connection wiring line, an insulating film, and a capacitance wiring line. The connection wiring line is formed over a gate electrode and an active layer of a TFT of a pixel, and is connected to the active layer. The insulating film is formed on the connection wiring line. The capacitance wiring line is formed on the insulating film. This structure enables the capacitor storage to overlap the TFT, thereby increasing the capacity of the capacitor storage while keeping the aperture ratio from lowering. Accordingly, a change in gate voltage due to leakage or other causes can be avoided to prevent a change in luminance of an OLED and flickering of screen in analog driving.
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Citations
20 Claims
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1. A light-emitting device including a pixel portion, the pixel portion comprising:
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a first transistor and a second transistor each including a channel formation region, a source, and a drain; a first insulating film over the channel formation region of the first transistor and the channel formation region of the second transistor; a first gate electrode over and in contact with the first insulating film, the first gate electrode overlapping with the channel formation region of the first transistor; a second gate electrode over and in contact with the first insulating film, the second gate electrode overlapping with the channel formation region of the second transistor; a second insulating film over and in contact with the first gate electrode and the second gate electrode; a first wiring over and in contact with the second insulating film, the first wiring including a region which overlaps with the second gate electrode, wherein a capacitor comprises the region and the second gate electrode overlapping with the region; a third insulating film over the first wiring; a pixel electrode over and in contact with the third insulating film, the pixel electrode being electrically connected to one of the source and the drain of the second transistor; and a second wiring over and in contact with the third insulating film, wherein the second wiring does not overlap with the region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A light-emitting device including a pixel portion, the pixel portion comprising:
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a plastic substrate; a first transistor and a second transistor over the plastic substrate, the first transistor and the second transistor each including a channel formation region, a source, and a drain; a first insulating film over the channel formation region of the first transistor and the channel formation region of the second transistor; a first gate electrode over and in contact with the first insulating film, the first gate electrode overlapping with the channel formation region of the first transistor; a second gate electrode over and in contact with the first insulating film, the second gate electrode overlapping with the channel formation region of the second transistor; a second insulating film over and in contact with the first gate electrode and the second gate electrode; a first wiring over and in contact with the second insulating film, the first wiring including a region which overlaps with the second gate electrode, wherein a capacitor comprises the region and the second gate electrode overlapping with the region; a third insulating film over the first wiring; a pixel electrode over and in contact with the third insulating film, the pixel electrode being electrically connected to one of the source and the drain of the second transistor; and a second wiring over and in contact with the third insulating film, wherein the second wiring does not overlap with the region. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification