Liquid crystal display device

1. A liquid crystal display device, comprising a TFT substrate comprising:

a plurality of pixel electrodes having potentials controlled by a plurality of transistors; and

a common electrode having a common potential supplied,

wherein the TFT substrate comprises:

an A wiring layer;

a B wiring layer, which is formed above the A wiring layer through an intermediate layer of a first insulating layer; and

a C wiring layer, which is formed above the B wiring layer through an intermediate layer of a second insulating layer,

wherein a first wiring layer of the A, B, or C wiring layers comprises a plurality of gate signal lines for supplying a gate signal to the plurality of transistors,

wherein a second wiring layer different from the first wiring layer comprising the plurality of gate signal lines, comprises:

a plurality of common signal lines for supplying the common potential to the common electrode; and

a common signal bus line for connecting together ends of at least two of the plurality of common signal lines, the common signal bus line being made of a conductor,

wherein a third wiring layer different from the first wiring layer comprising the plurality of gate signal lines and the second wiring layer comprising the plurality of common signal lines and the common signal bus line, comprises a plurality of data signal lines for supplying a plurality of data signals to the plurality of transistors,

wherein at least one of the first wiring layer comprising the plurality of gate signal lines and the third wiring layer comprising the plurality of data signal lines, comprises a common potential bus line for supplying the common potential to the plurality of common signal lines, and

wherein the A wiring layer comprises the plurality of gate signal lines,

wherein the B wiring layer comprises the plurality of data signal lines and the common potential bus line, and

wherein the C wiring layer comprises the plurality of common signal lines and the common signal bus line,

wherein the TFT substrate further comprises an interlayer connecting portion for connecting the common signal bus line and the common potential bus line to each other, the interlayer connecting portion being made of a conductor, and

wherein the interlayer connecting portion comprises:

a connecting portion having a planer shape, which is formed above the C wiring layer through an intermediate layer of a third insulating layer;

a first pass-through portion that passes through the third insulating layer to connect the connecting portion and the common signal bus line to each other; and

a second pass-through portion that passes through the third insulating layer, the C wiring layer, and the second insulating layer to connect the connecting portion and the common potential bus line to each other.

2. The liquid crystal display device according to claim 1 , wherein the at least two of the plurality of common signal lines are formed so as to protrude and extend from the common signal bus line.

3. The liquid crystal display device according to claim 1 ,

wherein the TFT substrate has a surface including a display region in which the plurality of pixel electrodes are formed and a non-display region that surrounds the display region, and

wherein the common signal bus line and the common potential bus line are formed in a region corresponding to the non-display region.

4. The liquid crystal display device according to claim 1 , wherein the common signal bus line and the common potential bus line at least partially overlap with each other.

5. The liquid crystal display device according to claim 1 , wherein the common signal bus line connects together the ends of all of the plurality of common signal lines.

6. The liquid crystal display device according to claim 1 , wherein the first pass-through portion of each of a plurality of the interlayer connecting portions is connected to a part of the common signal bus line, which is adjacent to one of the ends of the plurality of common signal lines.

7. The liquid crystal display device according to claim 1 , wherein the common potential bus line and the common signal bus line are connected to a common potential supply terminal of the TFT substrate, from which the common potential is supplied.

8. The liquid crystal display device according to claim 7 , wherein the common potential supply terminal is arranged in a long-side direction of the TFT substrate.

9. The liquid crystal display device according to claim 1 , wherein the interlayer connecting portion is made of a transparent electrode material.

10. The liquid crystal display device according to claim 1 , wherein the interlayer connecting portion is provided for each of the ends of the plurality of common signal lines.

11. The liquid crystal display device according to claim 1 , wherein the C wiring layer comprises a layer made of an organic material.

12. The liquid crystal display device according to claim 1 , wherein the common signal bus line and the common potential bus line are formed in a short-side direction of the TFT substrate.

13. The liquid crystal display device according to claim 1 , wherein the common signal bus line is formed in a long-side direction of the TFT substrate.

14. A liquid crystal display device, comprising a TFT substrate comprising:

a plurality of pixel electrodes having potentials controlled by a plurality of transistors; and

a common electrode having a common potential supplied,

wherein the TFT substrate comprises:

an A wiring layer;

a B wiring layer, which is formed above the A wiring layer through an intermediate layer of a first insulating layer; and

a C wiring layer, which is formed above the B wiring layer through an intermediate layer of a second insulating layer,

wherein a first wiring layer of the A, B, or C wiring layers comprises a plurality of gate signal lines for supplying a gate signal to the plurality of transistors,

wherein a second wiring layer different from the first wiring layer comprising the plurality of gate signal lines, comprises:

a plurality of common signal lines for supplying the common potential to the common electrode; and

a common signal bus line for connecting together ends of at least two of the plurality of common signal lines, the common signal bus line being made of a conductor,

wherein a third wiring layer different from the first wiring layer comprising the plurality of gate signal lines and the second wiring layer comprising the plurality of common signal lines and the common signal bus line, comprises a plurality of data signal lines for supplying a plurality of data signals to the plurality of transistors,

wherein at least one of the first wiring layer comprising the plurality of gate signal lines and the third wiring layer comprising the plurality of data signal lines, comprises a common potential bus line for supplying the common potential to the plurality of common signal lines, and

wherein the A wiring layer comprises the plurality of gate signal lines and the common potential bus line,

wherein the B wiring layer comprises the plurality of data signal lines, and

wherein the C wiring layer comprises the plurality of common signal lines and the common signal bus line,

wherein the TFT substrate further comprises an interlayer connecting portion for connecting the common signal bus line and the common potential bus line to each other, the interlayer connecting portion being made of a conductor, and

wherein the interlayer connecting portion comprises:

a connecting portion having a planer shape, which is formed above the C wiring layer through an intermediate layer of a third insulating layer;

a first pass-through portion that passes through the third insulating layer to connect the connecting portion and the common signal bus line to each other; and

a second pass-through portion that passes through the third insulating layer, the C wiring layer, the second insulating layer, the B wiring layer, and the first insulating layer to connect the connecting portion and the common potential bus line to each other.

15. A liquid crystal display device, comprising a TFT substrate comprising:

a plurality of pixel electrodes having potentials controlled by a plurality of transistors; and

a common electrode having a common potential supplied,

wherein the TFT substrate comprises:

an A wiring layer;

a B wiring layer, which is formed above the A wiring layer through an intermediate layer of a first insulating layer; and

a C wiring layer, which is formed above the B wiring layer through an intermediate layer of a second insulating layer,

wherein a first wiring layer of the A, B, or C wiring layers comprises a plurality of gate signal lines for supplying a gate signal to the plurality of transistors,

wherein a second wiring layer different from the first wiring layer comprising the plurality of gate signal lines, comprises:

a plurality of common signal lines for supplying the common potential to the common electrode; and

a common signal bus line for connecting together ends of at least two of the plurality of common signal lines, the common signal bus line being made of a conductor,

wherein a third wiring layer different from the first wiring layer comprising the plurality of gate signal lines and the second wiring layer comprising the plurality of common signal lines and the common signal bus line, comprises a plurality of data signal lines for supplying a plurality of data signals to the plurality of transistors,

wherein at least one of the first wiring layer comprising the plurality of gate signal lines and the third wiring layer comprising the plurality of data signal lines, comprises a common potential bus line for supplying the common potential to the plurality of common signal lines, and

wherein the A wiring layer comprises the plurality of gate signal lines,

wherein the B wiring layer comprises the plurality of data signal lines,

wherein the C wiring layer comprises the plurality of common signal lines and the common signal bus line,

wherein the common potential bus line comprises an A wiring layer common potential bus line formed in the A wiring layer and a B wiring layer common potential bus line formed in the B wiring layer,

wherein the TFT substrate further comprises an interlayer connecting portion for connecting the common signal bus line and the common potential bus line to each other, the interlayer connecting portion being made of a conductor, and

wherein the interlayer connecting portion comprises:

a first interlayer connecting portion comprising:

a first connecting portion having a planar shape, which is formed above the C wiring layer through an intermediate layer of a third insulating layer;

a first pass-through portion that passes through the third insulating layer to connect the first connecting portion and the common signal bus line to each other; and

a second pass-through portion that passes through the third insulating layer, the C wiring layer, and the second insulating layer to connect the first connecting portion and the B wiring layer common potential bus line to each other; and

a second interlayer connecting portion comprising:

a second connecting portion having a planar shape, which is formed above the C wiring layer through an intermediate layer of the third insulating layer;

a third pass-through portion that passes through the third insulating layer to connect the second connecting portion and the common signal bus line to each other; and

a fourth pass-through portion that passes through the third insulating layer, the C wiring layer, the second insulating layer, the B wiring layer, and the first insulating layer to connect the second connecting portion and the A wiring layer common potential bus line to each other.