Liquid crystal display device
A liquid crystal display device is configured to prevent the appearance on its display of a black stain stemming from a drop in volume resistivity of liquid crystal caused by ions therein. The device includes a thin-film transistor (TFT) substrate and a counter substrate bonded together along the periphery thereof by a seal material. The TFT substrate and the counter substrate have liquid crystal sandwiched therebetween and include a display area. A second wall is formed outside the display area over the TFT substrate. A second electrode is formed over the second wall. A first wall is formed between the second wall and the display area. A first electrode is formed over the first wall. The first wall has a gap against the counter substrate.
1. A liquid crystal display device comprising a thin-film transistor (TFT) substrate and a counter substrate bonded together along the periphery thereof by a seal material, the TFT substrate and the counter substrate having liquid crystal layer sandwiched therebetween and including a display area,
wherein a second wall is formed outside the display area on the TFT substrate;
the second wall is a wall of a second protrusion protruding from the TFT substrate toward the counter substrate,
a second electrode is formed at least on the second wall;
a first wall is formed between the second wall and the display area;
the first wall is a wall of a first protrusion protruding from the TFT substrate toward the counter substrate,
a first electrode is formed at least on the first wall facing the second wall;
the liquid crystal layer exists between the first wall and the second wall;
at least a portion of the second wall overlaps with the seal material in a plan view;
the first wall has a gap against the counter substrate;
the gap is smaller than a thickness of the liquid crystal layer in the display area; and
voltages applied to the first electrode and the second electrode are different.
2. The liquid crystal display device according to claim 1 , wherein the height of the first wall, represented by h 1 , and the thickness of a liquid crystal layer in the display area, represented by g, are in a relationship defined as g/3≤h 1 ≤2g/3.
3. The liquid crystal display device according to claim 1 , wherein the height of the second wall, represented by h 2 , and the thickness of a liquid crystal layer in the display area, represented by g, are in a relationship defined as g/3≤h 2 ≤2g/3.
4. The liquid crystal display device according to claim 1 , wherein the first wall is formed in a manner surrounding the entire display area.
5. The liquid crystal display device according to claim 1 , wherein the first wall is formed in a manner surrounding the display area with space in between.
6. The liquid crystal display device according to claim 1 , wherein the first wall is formed only at locations corresponding to the corners of the display area.
7. The liquid crystal display device according to claim 1 , wherein the first wall is formed only at a location corresponding to one of multiple corners of the display area.
8. The liquid crystal display device according to claim 1 , wherein the liquid crystal display device is an in-plane-switching (IPS) liquid crystal display device having a fourth electrode formed over a third electrode with an insulating film interposed therebetween, the liquid crystal being driven by a voltage impressed between the third electrode and the fourth electrode; and
wherein the first electrode is formed with the same layer as that of the third electrode.
9. The liquid crystal display device according to claim 1 , wherein the liquid crystal display device is an in-plane-switching (IPS) liquid crystal display device having the fourth electrode formed over the third electrode with an insulating film interposed therebetween, the liquid crystal being driven by a voltage impressed between the third electrode and the fourth electrode; and
wherein the first electrode is formed with the same layer as that of the fourth electrode.
10. The liquid crystal display device according to claim 1 , wherein the liquid crystal display device is a liquid crystal display device operating on a twisted nematic (TN) method or a vertical alignment (VA) method and having pixel electrodes formed on the side of the TFT substrate and a common electrode on the side of the counter substrate; and
wherein the first electrode is formed with the same layer as that of the pixel electrodes.
11. The liquid crystal display device according to claim 1 , wherein the first electrode is formed on at least in part of a top surface of the first protrusion, and the second electrode is formed on at least in part of a top surface of the second protrusion.
12. A liquid crystal display device comprising a thin-film transistor (TFT) substrate and a counter substrate bonded together along the periphery thereof by a seal material, the TFT substrate and the counter substrate having liquid crystal layer sandwiched therebetween and including a display area,
wherein:
a second electrode is formed in the seal material on the TFT substrate;
a first wall is formed between the second electrode and the display area;
the first wall is a wall of a first protrusion protruding from the TFT substrate toward the counter substrate;
a first electrode is formed at least on the first wall facing the seal material;
the liquid crystal layer exists between the first wall and the seal material;
voltages applied to the first electrode and the second electrode are different;
the first wall has a gap against the counter substrate; and
the gap is smaller than a thickness of the liquid crystal layer in the display area.
13. The liquid crystal display device according to claim 12 , wherein the height of the first wall, represented by h 1 , and the thickness of a liquid crystal layer in the display area, represented by g, are in a relationship defined as g/3≤h 1 ≤2g/3.
14. The liquid crystal display device according to claim 12 , wherein the first electrode is formed on at least in part of a top surface of the first protrusion.