Liquid crystal display device having increased brightness at a peripheral region of a pixel

• US 9,523,893 B2
• Filed: 12/17/2014
• Issued: 12/20/2016
• Est. Priority Date: 12/18/2013
• Status: Active Grant

• Current Assignee: Japan Display Incorporated
• Original Assignee: Japan Display Incorporated
• Inventors: Tsuruma, Takeyuki, Yamaguchi, Hidemasa
• Primary Examiner(s): Qi, Mike
• Application Number:
  US14/573,077
• Publication Number:
  US 20150168790A1
• Time in Patent Office: 734 Days
• Field of Search: 349/141, 349/146, 349/144
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2202/103 a-Si

Abstract

In order to increase the transmittance around a pixel and to increase the brightness of the screen in an IPS mode liquid crystal display device, a pixel electrode with a slit is formed on a common electrode through an interlayer insulating film. An opening is formed in the common electrode on the outside of the end portion of the pixel electrode as seen in a plane view. Because of the presence of the opening, the electric field lines from the end portion of the pixel electrode reach the layer above the liquid crystal layer and reach further away from the end portion of the pixel electrode, so that it is possible to increase the control ability to the liquid crystal around the pixel. As a result, the pixel transmittance can be increased as a whole and the brightness of the screen can be increased.

Claims

1. A liquid crystal display device comprising:

a TFT substrate in which scanning lines, video signal lines, and pixel electrodes are formed;

a counter substrate; and

a liquid crystal layer interposed between the TFT substrate and the counter substrate,

wherein the pixel electrode has strips and a slit portion,

wherein a common electrode is formed in a planar shape between the pixel electrode and the TFT substrate,

wherein an interlayer insulating film is formed between the pixel electrode and the common electrode,

wherein the common electrode has an opening extending in the direction in which the strips extend and along one of the strips of the pixel electrode,

wherein the opening is formed between the pixel electrode and one of the video signal lines, in a plan view,

wherein the opening is filled with the interlayer insulating film,

wherein the distance between the end portion in an extending direction of the scanning lines of the pixel electrode, and the end portion of the opening of the common electrode on the side far from the end portion of the pixel electrode in the extending direction of the scanning lines, is in the range of 0.25 to 5 μ

m.

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

wherein the opening does not overlap the video signal line as seen in a plan view.

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

wherein the distance between the end portion of the pixel electrode and the end portion of the opening of the common electrode on the side far from the end portion of the pixel electrode is in the range of 0.5 to 3 μ

m.

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

wherein the opening of the common electrode does not overlap the slit of the pixel electrode as seen in a plan view.

5. The liquid crystal display device according to claim 4,

wherein the opening does not overlap the video signal line as seen in a plan view.

6. The liquid crystal display device according to claim 4,

wherein the distance between the end portion of the pixel electrode in the extending direction of the scanning lines, and the end portion of the opening of the common electrode on the side far from the end portion of the pixel electrode in the extending direction of the scanning lines is in the range of 0.5 to 3 μ

m.

7. A liquid crystal display device comprising:

a TFT substrate in which pixels each having a pixel electrode formed in an area surrounded by scanning lines extending in a first direction, and video signal lines extending in a second direction, are formed in a matrix form;

a counter substrate; and

a liquid crystal layer interposed between the TFT substrate and the counter substrate,

wherein the pixel electrode is a single strip extending in the second direction,

wherein a common electrode is formed between the pixel electrode and the TFT substrate,

wherein an interlayer insulating film is formed between the pixel electrode and the common electrode,

wherein the common electrode has an opening extending in the second direction, and along the single strip,

wherein the opening is formed between the pixel electrode and one of the video signal lines, in a plan view, and

wherein the opening is filled with the interlayer insulating film, and

wherein the distance between the end portion of the pixel electrode in the first direction, and the end portion of the opening of the common electrode on the side far from the end portion of the pixel electrode in the first direction is in the range of 0.25 to 5 μ

m.

8. The liquid crystal display device according to claim 7,

wherein the opening does not overlap the video signal line as seen in a plan view.

9. The liquid crystal display device according to claim 7,

wherein the distance between the end portion of the pixel electrode in the first direction, and the end portion of the opening of the common electrode on the side far from the end portion of the pixel electrode in the first direction is in the range of 0.5 to 3 μ

m.