Liquid crystal display device
It is an object of the present invention to provide a liquid crystal display device which has a wide viewing angle and less color-shift depending on an angle at which a display screen is seen and can display an image favorably recognized both outdoors in sunlight and dark indoors (or outdoors at night). The liquid crystal display device includes a first portion where display is performed by transmission of light and a second portion where display is performed by reflection of light. Further, a liquid crystal layer includes a liquid crystal molecule which rotates parallel to an electrode plane when a potential difference is generated between two electrodes of a liquid crystal element provided below the liquid crystal layer.
1. A liquid crystal display device comprising:
a transistor comprising:
a gate electrode;
a semiconductor layer overlapping with the gate electrode; and
a gate insulating layer between the gate electrode and the semiconductor layer;
a first conductive layer on and in electrical contact with the semiconductor layer;
a second conductive layer on a same plane and of a same material as the first conductive layer;
a first insulating layer over the transistor and over the first and the second conductive layers;
a transmitting common electrode overlapping the second conductive layer;
a third conductive layer on and in direct contact with the transmitting common electrode, the third conductive layer overlapping the second conductive layer and the first insulating layer;
a second insulating layer on and in direct contact with the first insulating layer and with the third conductive layer; and
a transmitting pixel electrode on and in direct contact with the second insulating layer, overlapping the transmitting common electrode, and in electrical contact with the first conductive layer via a second contact hole in the second insulating layer and a first contact hole in the first insulating layer,
wherein the first contact hole and the second contact hole overlap.
2. A liquid crystal display device comprising:
a transistor comprising:
a gate electrode;
a semiconductor layer overlapping with the gate electrode; and
a gate insulating layer between the gate electrode and the semiconductor layer;
a first conductive layer on and in electrical contact with the semiconductor layer;
a second conductive layer on a same plane and of a same material as the first conductive layer;
a first insulating layer over the transistor and on and in direct contact with the first and the second conductive layers;
a transmitting common electrode overlapping the second conductive layer;
a third conductive layer on and in direct contact with the transmitting common electrode, the third conductive layer overlapping the second conductive layer and the first insulating layer;
a second insulating layer on and in direct contact with the first insulating layer and with the third conductive layer; and
a transmitting pixel electrode on and in direct contact with the second insulating layer, overlapping the transmitting common electrode, and in electrical contact with the first conductive layer via a second contact hole in the second insulating layer and a first contact hole in the first insulating layer,
wherein the first contact hole and the second contact hole overlap.
3. A liquid crystal display device comprising:
a transistor comprising:
a gate electrode;
a semiconductor layer overlapping with the gate electrode; and
a gate insulating layer between the gate electrode and the semiconductor layer;
a first conductive layer on and in electrical contact with the semiconductor layer;
a second conductive layer on a same plane and of a same material as the first conductive layer;
a first insulating layer over the transistor and over the first and the second conductive layers;
a transmitting common electrode overlapping the second conductive layer;
a third conductive layer on and in direct contact with the transmitting common electrode, the third conductive layer overlapping the second conductive layer and the first insulating layer;
a second insulating layer on and in direct contact with the first insulating layer and with the third conductive layer; and
a transmitting pixel electrode on and in direct contact with the second insulating layer, overlapping the transmitting common electrode, and in electrical contact with the first conductive layer via a second contact hole in the second insulating layer and a first contact hole in the first insulating layer,
wherein the first contact hole and the second contact hole overlap, and
wherein a bottom portion of the second contact hole is narrower than a top portion of the first contact hole when seen in a cross-section view.
4. The liquid crystal display device according to claim 1 , wherein the third conductive layer is a reflecting common electrode.
5. The liquid crystal display device according to claim 2 , wherein the third conductive layer is a reflecting common electrode.
6. The liquid crystal display device according to claim 3 , wherein the third conductive layer is a reflecting common electrode.
7. The liquid crystal display device according to claim 1 , wherein the third conductive layer is thicker than the transmitting common electrode.
8. The liquid crystal display device according to claim 2 , wherein the third conductive layer is thicker than the transmitting common electrode.
9. The liquid crystal display device according to claim 3 , wherein the third conductive layer is thicker than the transmitting common electrode.
10. The liquid crystal display device according to claim 1 , wherein the first insulating layer overlaps the transmitting common electrode.
11. The liquid crystal display device according to claim 2 , wherein the first insulating layer overlaps the transmitting common electrode.
12. The liquid crystal display device according to claim 3 , wherein the first insulating layer overlaps the transmitting common electrode.
13. The liquid crystal display device according to claim 1 , wherein the gate electrode is over the semiconductor layer.
14. The liquid crystal display device according to claim 2 , wherein the gate electrode is over the semiconductor layer.
15. The liquid crystal display device according to claim 3 , wherein the gate electrode is over the semiconductor layer.
16. The liquid crystal display device according to claim 1 , further comprising a fourth conductive layer between the transmitting pixel electrode and the first conductive layer.
17. The liquid crystal display device according to claim 2 , further comprising a fourth conductive layer between the transmitting pixel electrode and the first conductive layer.
18. The liquid crystal display device according to claim 3 , further comprising a fourth conductive layer between the transmitting pixel electrode and the first conductive layer.
19. The liquid crystal display device according to claim 1 , further comprising a third insulating layer between the semiconductor layer and the first conductive layer.
20. The liquid crystal display device according to claim 2 , further comprising a third insulating layer between the semiconductor layer and the first conductive layer.
21. The liquid crystal display device according to claim 3 , further comprising a third insulating layer between the semiconductor layer and the first conductive layer.
22. An electronic appliance comprising the liquid crystal display device according to claim 1 .
23. An electronic appliance comprising the liquid crystal display device according to claim 2 .
24. An electronic appliance comprising the liquid crystal display device according to claim 3 .
25. The liquid crystal display device according to claim 1 , wherein the transmitting common electrode is electrically connected to the second conductive layer.
26. The liquid crystal display device according to claim 2 , wherein the transmitting common electrode is electrically connected to the second conductive layer.
27. The liquid crystal display device according to claim 3 , wherein the transmitting common electrode is electrically connected to the second conductive layer.
28. The liquid crystal display device according to claim 1 , wherein the transmitting common electrode is in direct contact with the second conductive layer.
29. The liquid crystal display device according to claim 2 , wherein the transmitting common electrode is in direct contact with the second conductive layer.
30. The liquid crystal display device according to claim 3 , wherein the transmitting common electrode is in direct contact with the second conductive layer.