Liquid crystal display apparatus

• US 7,361,934 B2
• Filed: 06/07/2006
• Issued: 04/22/2008
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: InterDigital Patent Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Casio Computer Company Limited
• Inventors: Ishii, Hiromitsu
• Primary Examiner(s): Jackson; Jerome
• Assistant Examiner(s): Ho; Anthony
• Application Number:
  US11/448,631
• Publication Number:
  US 20060278873A1
• Time in Patent Office: 685 Days
• Field of Search: 257/72, 257/59
• US Class Current: 257/72
• 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
• CPC Class Codes: G02F 1/13629 Multilayer wirings
• CPC Class Codes: G02F 2201/40 Arrangements for improving the aperture ratio
• CPC Class Codes: G02F 2203/01 transmissive

Abstract

A thin film transistor is provided in a vicinity of a crossing region of scanning and the data lines on a first substrate. A pixel electrode is connected with the thin film transistor. A transparent electroconductive layer which is applied with a common potential is provided between the pixel electrodes and the scanning lines and data lines to cover the scanning and date lines, is superimposed on peripheral portions of the pixel electrodes on both sides. An insulating film is formed between the pixel electrodes and the electroconductive layer. An opposed electrode is formed on a second substrate to correspond to the pixel electrodes. A liquid crystal is provided between the pixel electrodes and opposed electrode.

Claims

1. A liquid crystal display apparatus comprising:

a first substrate;

a second substrate opposing the first substrate;

a plurality of scanning lines which are formed on a side of the first substrate and extend in one direction;

a plurality of data lines which are formed on the side of the first substrate and extend in a direction crossing the scanning lines;

a plurality of thin film transistors each of which is provided in a vicinity of a respective crossing region of the scanning lines and the data lines on the side of the first substrate, each transistor including a semiconductor thin film, a gate electrode arranged on a side of the semiconductor thin film and source and drain electrodes respectively connected with source and drain regions of the semiconductor thin film;

a plurality of pixel electrodes each of which is connected with a respective one of the thin film transistors and which are arranged with a space between adjacent pixel electrodes;

an electroconductive layer which is provided between the pixel electrodes and the scanning lines and the data lines to cover the data lines, the electroconductive layer being disposed in a region including the spaces between the adjacent pixel electrodes and superimposed on at least parts of peripheral portions of the pixel electrodes, and applied with a common potential;

an insulating film formed between the pixel electrodes and the electroconductive layer;

at least one opposed electrode formed on a side of the second substrate to correspond to the pixel electrodes; and

a liquid crystal provided between the pixel electrodes and said at least one opposed electrode;

wherein the electroconductive layer comprises a light-shielding, electroconductive film which has a width smaller than a width of the spaces between the adjacent pixel electrodes and a transparent electroconductive film which has a width larger than the width of light-shielding electroconductive film.

2. The liquid crystal display apparatus according to claim 1, wherein a potential with which a black display is observed is applied between the electroconductive layer and the opposed electrode.

3. The liquid crystal display apparatus according to claim 2, wherein the liquid crystal is a Twisted Nematic liquid crystal having a twist angle of 90°

.

4. The liquid crystal display apparatus according to claim 1, wherein the electroconductive layer has a lattice-like shape and covers the scanning lines and the data lines.

5. The liquid crystal display apparatus according to claim 1, wherein each of the thin film transistors is configured to transmit light therethrough, and each of the pixel electrodes covers the respective thin film transistor.

6. The liquid crystal display apparatus according to claim 5, wherein the semiconductor thin film of the thin film transistor is formed of a metal oxide, and the drain and source electrodes and the gate electrode are formed of a metal oxide containing impurities.

7. The liquid crystal display apparatus according to claim 6, wherein the drain and source electrodes are provided on the semiconductor thin film.

8. The liquid crystal display apparatus according to claim 6, wherein the gate electrode of the thin film transistor is formed of a metal oxide containing p-type impurities.

9. The liquid crystal display apparatus according to claim 6, wherein the scanning line is electrically connected with the gate electrode, the scanning line is formed of the same material as that of the gate electrode, the data line is electrically connected with one of the drain and source electrodes, and the data line is formed of the same material as that of said one of the drain and source electrodes.

10. The liquid crystal display apparatus according to claim 5, wherein the semiconductor thin film of the thin film transistor is formed of a metal oxide, the gate electrode is formed of a metal oxide containing impurities, and the drain and source electrodes are formed of a transparent electroconductive material.

11. The liquid crystal display apparatus according to claim 10, wherein the drain and source electrodes are situated under the semiconductor thin film.

12. The liquid crystal display apparatus according to claim 1, wherein the electroconductive layer has a part which substantially covers an entire region of the thin film transistor.

13. The liquid crystal display apparatus of claim 1, wherein the transparent electroconductive film completely covers the entire light-shielding electroconductive film.

14. The liquid crystal display apparatus of claim 1, wherein the transparent electroconductive film covers upper and side surfaces of the light-shielding electroconductive film.

15. The liquid crystal display apparatus of claim 1, wherein the light-shielding electroconductive film is arranged relative to the pixel electrodes such that there is no overlap between the light-shielding electroconductive film and the pixel electrodes.

16. The liquid crystal display apparatus of claim 1, wherein both side edge portions of the transparent electro-conductive film in a width direction are arranged to overlap portions of the pixel electrodes.

17. The liquid crystal display apparatus of claim 1, wherein the transparent electroconductive film is arranged on an upper surface of the light-shielding electroconductive film.

18. The liquid crystal display apparatus of claim 1, wherein the light-shielding electroconductive film and the transparent electroconductive film are laminated to each other.

19. The liquid crystal display apparatus of claim 1, wherein the light-shielding electroconductive film is formed on and in contact with the insulating film and the transparent electroconductive film is formed on and in contact with the light-shielding electroconductive film.

20. A liquid crystal display apparatus comprising:

a first substrate;

a second substrate opposing the first substrate;

a plurality of scanning lines which are formed on a side of the first substrate and extend in one direction;

a plurality of data lines which are formed on the side of the first substrate and extend in a direction crossing the scanning lines;

a plurality of thin film transistors each of which is arranged in a vicinity of a respective crossing region of the scanning lines and the data lines on the side of the first substrate, each of the transistors including a semiconductor thin film, a gate electrode arranged on a side of the semiconductor thin film and source and drain electrodes respectively connected with source and drain regions of the semiconductor thin film;

a plurality of pixel electrodes each of which is connected with a respective one of the thin film transistors and which are arranged with a space between adjacent pixel electrodes;

a transparent electroconductive layer arranged between the pixel electrodes and the scanning lines and the data lines to cover the data lines, the electroconductive layer being disposed in a region including the spaces between the adjacent pixel electrodes and superimposed on at least parts of peripheral portions of the adjacent pixel electrodes, and applied with a common potential;

an insulating film formed between the pixel electrodes and the electroconductive layer,

at least one opposed electrode formed on a side of the second substrate to correspond to the pixel electrodes and applied with a common potential which is the same potential as the potential applied to the transparent electroconductive layer; and

a liquid crystal arranged between the pixel electrodes and said at least one opposed electrode;

wherein the liquid crystal has a first part corresponding to the spaces between the pixel electrodes and a second part corresponding to peripheral portions of the pixel electrodes to which the transparent electroconductive layer is superimposed, and wherein only the first part of the liquid crystal is fully and constantly set in a black display state.