Liquid crystal display

• US 20020140891A1
• Filed: 08/15/2001
• Published: 10/03/2002
• Est. Priority Date: 02/28/2001
• Status: Active Grant

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated)
• Inventors: Tomioka, Yasushi, Kondo, Katsumi, Umeda, Yoshiyuki
• Granted Patent: US 6,590,627 B2
• Time in Patent Office: Days
• US Class Current: 349/141
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

The present invention provides a liquid crystal display of high image quality which can be driven at a low voltage and shows a lowered inhomogeneity of display caused by an after image phenomenon.

The liquid crystal display comprises one pair of substrates which are a first substrate and a second substrate, at least one of which is transparent, a liquid crystal layer and a color filter layer provided between the two substrates, a plurality of thin film transistors provided on the first substrate and connected to an image signal wiring and a scanning signal wiring, a common electrode giving a standard potential, and a pixel electrode connected to the thin film transistors and placed opposite to the common electrode in a pixel region, wherein the common electrode and pixel electrode are placed in different layers from each other through an interlaminar insulating film in the form of layer comprising at least two layers comprising the color filter layer.

Claims

1. A liquid crystal display comprising one pair of substrates which are a first substrate and a second substrate wherein at least one of the substrates is transparent, a liquid crystal layer and a color filter layer both provided between said one pair of substrates, a plurality of thin film transistors which are provided on the first substrate existing on a downside of the color filter layer and are connected to an image signal wiring and a scanning signal wiring, a common electrode giving a standard potential, and a pixel electrode connected to the thin film transistors and placed opposite to the common electrode in a pixel region,

wherein said common electrode and said pixel electrode are placed in different layers from each other through an interlaminar insulating film in the form of layer comprising at least two layers comprising said color filter layer and an orientation direction of liquid crystal molecules of the liquid crystal layer is controlled by a voltage applied through the interlaminar insulating film and between the common electrode and the pixel electrode to make display.

2. The liquid crystal display comprising one pair of substrates which are a first substrate and a second substrate wherein at least one of the substrate is transparent, and a liquid crystal layer and a color filter layer both provided between said one pair of substrates, wherein said color filter layer is placed close to the first substrate and the liquid crystal layer is placed between the color filter layer and the second substrate,

wherein a plurality of scanning signal wirings, a plurality of image signal wirings and a plurality of transistors connected to the image signal wirings and the scanning signal wirings are placed on the first substrate existing on a downside of the color filter layer,

each region surrounded by the plurality of scanning signal wirings and the image signal wirings constitutes at least one pixel, and each pixel is provided with a common electrode connected with a common electrode wiring over a plurality of pixels to give a standard potential and a pixel electrode connected to the transistor and placed opposite to the common electrode in the pixel region,

wherein said common electrode and said pixel electrode are placed in different layers from each other through an interlaminar insulating film in the form of layer comprising at least two layers comprising said color filter layer and an orientation direction of liquid crystal molecules of the liquid crystal layer is controlled by a voltage applied through the interlaminar insulating film and between the common electrode and the pixel electrode to make display.

3. The liquid crystal display according to claim 2, wherein said common electrode coats at least a part of said image signal wiring and said scanning signal wiring through an insulating film.

4. The liquid crystal display according to claim 3, wherein said insulating film is an interlaminar insulating film comprising at least two layers.

5. The liquid crystal display according to claim 2, wherein at least one layer of said interlaminar insulating film is made of an organic substance.

6. The liquid crystal display according to claim 2, wherein an insulating overcoat layer is provided in a boundary part between two kinds of color filter layers on said image signal wiring or said scanning signal wiring, and said common electrode is formed on said overcoat layer.

7. The liquid crystal display according to claim 2, wherein an overcoat layer for protecting said color filter is provided on an upside of said color filter layer, and said common electrode is formed on said overcoat layer.

8. The liquid crystal display according to claim 2, wherein said common electrode or said common electrode wiring is formed lattice-wise so as to surround said pixel.

9. The liquid crystal display according to claim 2, wherein an overcoat layer for protecting said color filter is provided on an upside of said color filter layer, and said pixel electrode is formed on said overcoat layer.

10. The liquid crystal display according to claim 2, wherein said overcoat layer or said interlaminar insulating film is made of a photosensitive resin.

11. The liquid crystal display according to claim 2, wherein at least one member selected from the group consisting of said pixel electrode and said common electrode is constituted of a transparent electrode.

12. The liquid crystal display according to claim 11, wherein said transparent electrode is constituted of an ion doped titanium oxide film or an ion doped zinc oxide (ZnO) film.

13. The liquid crystal display according to claim 2, wherein said common electrode or said common electrode wiring is made of an alloy containing at least one member selected from the group consisting of Al, Cr, Mo, Ta and W.

14. The liquid crystal display according to claim 13, wherein an antireflection layer is formed on an upside of said common electrode or said common electrode wiring.

15. The liquid crystal display according to claim 14, wherein a film containing a black-colored pigment is formed as said antireflection layer.

16. The liquid crystal display according to claim 14, wherein a phase difference film is laminated as said antireflection layer.

17. The liquid crystal display according to claim 14, wherein said common electrode or said common electrode wiring is formed into a laminated structure containing a magnetic material as said antireflection layer.

18. The liquid crystal display according to claim 2, wherein the alignment direction of the liquid crystal molecule at two interfaces between said liquid crystal layer and alignment layers formed on said one pair of substrates are nearly in the same direction.

19. The liquid crystal display according to claim 18, wherein at least one of the alignment layers formed on said one pair of substrates is a photo-reactive material layer.

20. The liquid crystal display according to claim 2, wherein a pre tilt angle of said liquid crystal layer is 5 degrees or less.