Liquid crystal display device
View Patent ↗The liquid crystal display device includes a first substrate, a second substrate, and a liquid crystal layer between the first substrate and the second substrate. The first substrate includes a transistor including an oxide semiconductor film including a channel formation region; a pixel electrode electrically connected to the transistor; an insulating layer in contact with the pixel electrode; and a first common electrode in contact with the insulating layer. The second substrate faces the first substrate and includes a second common electrode. A negative liquid crystal material is used for the liquid crystal layer. The specific resistivity of the liquid crystal material is greater than or equal to 1.0×10 13 Ω·cm and less than or equal to 1.0×10 16 Ω·cm.
1. A liquid crystal display device comprising:
a first substrate comprising:
a transistor comprising a crystalline oxide semiconductor film in a channel formation region;
a pixel electrode electrically connected to one of a source electrode and a drain electrode of the transistor;
an insulating layer in contact with the pixel electrode; and
a first common electrode in contact with the insulating layer,
a second substrate facing the first substrate, the second substrate comprising a second common electrode; and
a liquid crystal layer comprising a liquid crystal material between the first substrate and the second substrate,
wherein a potential difference between the first common electrode and the second common electrode is smaller than a potential difference between the second common electrode and the pixel electrode,
wherein the potential difference between the second common electrode and the pixel electrode is smaller than a potential difference between the first common electrode and the pixel electrode, and
wherein a specific resistivity of the liquid crystal material is greater than or equal to 1.8×10 13 Ω·cm and less than or equal to 1.0×10 16 Ω·cm.
2. The liquid crystal display device according to claim 1 , wherein the crystalline oxide semiconductor film comprises In, Ga, and Zn.
3. The liquid crystal display device according to claim 1 , further comprising a planarization film between the first substrate and the pixel electrode.
4. The liquid crystal display device according to claim 1 , further comprising a color film between the second substrate and the second common electrode.
5. The liquid crystal display device according to claim 1 , wherein c-axes of the crystalline oxide semiconductor film are aligned in a direction perpendicular to a top surface of the crystalline oxide semiconductor film.
6. A liquid crystal display device comprising:
a first substrate comprising:
a transistor comprising a crystalline oxide semiconductor film in a channel formation region;
a pixel electrode electrically connected to one of a source electrode and a drain electrode of the transistor;
an insulating layer in contact with the pixel electrode; and
a first common electrode in contact with the insulating layer,
a second substrate facing the first substrate, the second substrate comprising a second common electrode; and
a liquid crystal layer between the first substrate and the second substrate,
wherein a potential difference between the first common electrode and the second common electrode is smaller than a potential difference between the second common electrode and the pixel electrode,
wherein the potential difference between the second common electrode and the pixel electrode is smaller than a potential difference between the first common electrode and the pixel electrode,
wherein the liquid crystal layer comprises a liquid crystal material with negative dielectric anisotropy, and
wherein a specific resistivity of the liquid crystal material with negative dielectric anisotropy is greater than or equal to 1.8×10 13 Ω·cm and less than or equal to 1.0×10 16 Ω·cm.
7. The liquid crystal display device according to claim 6 , wherein the crystalline oxide semiconductor film comprises In, Ga, and Zn.
8. The liquid crystal display device according to claim 6 , wherein a dielectric constant anisotropy of the liquid crystal material with negative dielectric anisotropy is 3.0.
9. The liquid crystal display device according to claim 6 , further comprising a planarization film between the first substrate and the pixel electrode.
10. The liquid crystal display device according to claim 6 , further comprising a color film between the second substrate and the second common electrode.
11. The liquid crystal display device according to claim 6 , wherein the first common electrode and the second common electrode are connected to different power supply lines.
12. The liquid crystal display device according to claim 6 , wherein c-axes of the crystalline oxide semiconductor film are aligned in a direction perpendicular to a top surface of the crystalline oxide semiconductor film.
13. A liquid crystal display device comprising:
a first substrate comprising:
a transistor comprising:
a gate electrode over the first substrate;
a gate insulating film over the gate electrode;
a crystalline oxide semiconductor film over the gate insulating film; and
a source electrode and a drain electrode over the crystalline oxide semiconductor film,
a first common electrode over and in direct contact with the gate insulating film;
an insulating layer over the first common electrode; and
a pixel electrode over the insulating layer, the pixel electrode electrically connected to one of the source electrode and the drain electrode,
a second substrate facing the first substrate, the second substrate comprising a second common electrode; and
a liquid crystal layer between the first substrate and the second substrate,
wherein the first common electrode and the second common electrode are connected to different power supply lines,
wherein a potential difference between the first common electrode and the second common electrode is smaller than a potential difference between the second common electrode and the pixel electrode,
wherein the potential difference between the second common electrode and the pixel electrode is smaller than a potential difference between the first common electrode and the pixel electrode,
wherein the liquid crystal layer comprises a liquid crystal material with negative dielectric anisotropy, and
wherein a specific resistivity of the liquid crystal material with negative dielectric anisotropy is greater than or equal to 1.8×10 13 Ω·cm and less than or equal to 1.0×10 16 Ω·cm.
14. The liquid crystal display device according to claim 13 , wherein the crystalline oxide semiconductor film comprises In, Ga, and Zn.
15. The liquid crystal display device according to claim 13 , wherein a dielectric constant anisotropy of the liquid crystal material with negative dielectric anisotropy is −3.0.
16. The liquid crystal display device according to claim 13 , further comprising a planarization film between the first substrate and the pixel electrode.
17. The liquid crystal display device according to claim 13 , further comprising a color film between the second substrate and the second common electrode.
18. The liquid crystal display device according to claim 13 , wherein c-axes of the crystalline oxide semiconductor film are aligned in a direction perpendicular to a top surface of the crystalline oxide semiconductor film.