Display device

• US 6,005,648 A
• Filed: 06/24/1997
• Issued: 12/21/1999
• Est. Priority Date: 06/25/1996
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Takemura, Yasuhiko, Zhang, Hongyong, Yamaguchi, Naoaki
• Primary Examiner(s): Kim, Robert H.
• Application Number:
  US08/881,872
• Time in Patent Office: 910 Days
• Field of Search: 349/42, 349/38, 349/141, 349/138, 349/139, 349/43
• US Class Current: 349/43
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode

Abstract

In an active matrix liquid-crystal display device, a metal common electrode 22 that also serves as a black matrix is disposed to cover the peripheral portion of a pixel electrode 24 which is formed of a transparent electrically conductive film. The common electrode 22 functions as the black matrix that covers the peripheral portion of a pixel and is held to a given potential, so that a region where the pixel electrode 24 and the common electrode 22 are overlapped with each other functions as an auxiliary capacitor 25. The auxiliary capacitor is structured through an insulation layer 23. The common electrode 22 is formed on the insulation layer 21 having a flatten surface to make the auxiliary capacitor 25 larger. With this structure, even though the insulation layer 23 is thinned to about 1 μm, a pin hole, leakage, etc., between the common electrode and the pixel electrode can be prevented, to thereby obtain a larger auxiliary capacitor.

Claims

1. An active matrix display device, comprising:

a source wiring;

a gate wiring, said source wiring and said gate wiring being disposed in the form of a lattice;

at least one pixel electrode disposed in a region surrounded by one of said source wiring and said gate wiring; and

a common electrode disposed between a layer of said pixel electrode and a layer of said source wiring and said gate wiring to cover said source wiring and said gate wiring, said common electrode comprising a material that blocks a visual light and being held to a given potential;

wherein a peripheral portion of said pixel electrode is overlapped with said common electrode in an overlapped region to form an auxiliary capacitor, and

wherein said common electrode is formed on a flattened surface of an organic region layer.

2. An active matrix display device according to claim 1, wherein an organic resin layer is interposed between said pixel electrode and said common electrode.

3. An active matrix display device according to claim 1 wherein said common electrode is disposed to be overlapped with an edge portion of said pixel electrode.

4. An active matrix display device according to claim 1 wherein said source wiring and said gate wiring are shielded from an incident light with said common electrode.

5. An active matrix display device according to claim 1, wherein the dielectric constant of the insulation layer interposed between said pixel electrode and said common electrode is higher than the dielectric constant of the organic resin layer on a surface of which said common electrode is formed.