Liquid crystal display device

• US 8,427,624 B2
• Filed: 07/08/2010
• Issued: 04/23/2013
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsui, Chikae, Sonoda, Hidehiro, Kunimatsu, Noboru
• Primary Examiner(s): Merlin, Jessica M
• Application Number:
  US12/832,221
• Publication Number:
  US 20110007233A1
• Time in Patent Office: 1,020 Days
• Field of Search: 349/153, 349/154, 349/190
• US Class Current: 349/153
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133519 Overcoatings
• CPC Class Codes: G02F 1/1337 Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
• CPC Class Codes: G02F 1/1339 Gaskets; Spacers; Sealing of cells
• 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 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence

Abstract

In an IPS type liquid crystal display device, a light shielding film, a red color filter, an overcoat film, and an alignment film are formed in this order on a counter substrate. However, the alignment film is not formed in a seal portion. When the alignment film is subjected to photo-alignment with ultraviolet radiation, a portion of the overcoat film not covered with the alignment film is degraded by ultraviolet radiation. In order to prevent moisture penetrating from the degraded overcoat film from reaching the light shielding film to thereby alter the light shielding film and from causing the peeling of the light shielding film, the red color filter is disposed below the overcoat film to block the moisture.

Claims

1. An IPS type liquid crystal display device comprising:

a TFT substrate including a display region where pixels each including a TFT and a pixel electrode are formed in a matrix and where a counter electrode is formed;

a counter substrate bonded to the TFT substrate with a sealing material in a seal portion at a periphery thereof and including a display region where a light shielding film and color filters of three colors are formed, an overcoat film is formed so as to cover the color filters of three colors, and an alignment film is formed in direct contact with the overcoat film so as to cover the overcoat film, wherein the overcoat film has a first region covered by the alignment film and a second region not covered by the alignment film, wherein a first portion of the second region is in direct contact with the sealing material and a second portion of the second region is exposed from both the sealing material and the alignment film; and

liquid crystal sealed between the TFT substrate and the counter substrate, wherein

in each pixel, transmittance of light is controlled by a voltage between the pixel electrode and the counter electrode;

in the counter substrate, the alignment film and the exposed second portion of the second region of the overcoat film are subjected to an alignment treatment by irradiating with radiation whereby the exposed second portion is degraded by the radiation, and the alignment film is not formed in the seal portion so that the overcoat film is not covered by the alignment film in the seal portion of the counter substrate; and

in the seal portion of the counter substrate, the light shielding film, a color filter of one color among the color filters of three colors, and the overcoat film are stacked in this order, and the sealing material is formed on the overcoat film,

whereby the color filter of one color is located between the overcoat film and the light shielding film and is configured to prevent moisture entering the exposed second portion of the overcoat film from reaching the underlying light shielding film.

2. The liquid crystal display device according to claim 1, wherein a conductive film is not formed on the overcoat film.

3. The liquid crystal display device according to claim 1, wherein the sealing material is in direct contact with the overcoat film.

4. The liquid crystal display device according to claim 2, wherein the sealing material is in direct contact with the overcoat film.