Multigap color LCD device

• US 6,593,981 B1
• Filed: 07/31/2000
• Issued: 07/15/2003
• Est. Priority Date: 07/31/2000
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Unate, Takao, Haim, Lee, Tamaoka, Kazuki, Yoshiga, Masahiro
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): AKKAPEDDI, PRASAD R
• Application Number:
  US09/628,838
• Time in Patent Office: 1,079 Days
• Field of Search: 349/106
• US Class Current: 349/106
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals

Abstract

A multigap color LCD device which prevents display non-uniformity arising from non-uniformity in cell thickness. The external measurements of a blue color filter within a LCD device are fabricated not to overlap the source buses and the gate buses, which surround an opposing picture element electrode, and the external measurements of a green color filter in the LCD device are fabricated to overlap a pair of source buses and a pair of gate buses, which surround the opposing picture element electrode. The distance between the green color filter and both the source buses and the gate buses, is set so that it approximately equals the distance between the blue color filter and the picture element electrode. In addition to liquid crystal, spacers are inserted between the two substrates to maintain uniformity in cell thickness. Red color filters may be the same width as the blue color filters, or wider, extending to the proximity of the blue color filters.

Claims

1. A multigap liquid crystal display device comprising in combination:

a) a thin film transistor (TFT) array substrate opposing a common electrode substrate, said TFT array substrate including a source bus and a gate bus formed on said TFT array substrate, said source bus and said gate bus intersecting to form a mesh pattern;

b) said source bus and said gate bus being formed approximately on a single plane, and said mesh pattern forming picture element electrodes which are thinner than said source bus or said gate bus;

c) said common electrode substrate comprising a black matrix made of thin film forming a net-like pattern on the inner surface of a glass substrate corresponding to said mesh pattern of said TFT array substrate;

d) red, green and blue color filters formed in said black matrix in said net-like pattern; and

e) the film thicknesses of said source bus, said gate bus, said blue color filters (tb), and said green color filters (tg) being such that the distance (d1) between opposing said green color filters an both said source bus and said gate bus is approximately equal to the distance (d2) between the opposing said blue color filters and said picture element electrodes.

2. The multigap liquid crystal display according to claim 1 further comprising a plurality of thin film transistors, one thin film transistor corresponding to each said picture element electrode, said thin film transistors being formed on the periphery of said mesh pattern.

3. The multigap liquid crystal display device according to claim 1, the thickness of said red color filters (tr), the thickness of said green color filter (tg), and the thickness of said blue color filter (tb) being such that tr<

tg<

tb.

4. The multigap liquid crystal display device according to claim 1, said common electrode substrate covering the red, green, and blue color filters over the entire surface area of said glass substrate on which said red, green, and blue color filters are formed.

5. The multigap liquid crystal display device according to claim 1, said TFT array substrate and said common electrode substrate being separated by spacers and disposed in close proximity to each other in an opposing manner, comprising liquid crystal substantially filling the space between said TFT array substrate and said common electrode substrate.

6. The multigap liquid crystal display device according to claim 1:

a) said blue color filters being small enough that they do not overlap either said source bus or said gate bus surrounding opposing said picture element electrodes; and

b) said green color filters being large enough that they overlap the pairs of source buses and the pairs of gate buses surrounding the opposing picture element electrodes.

7. The multigap liquid crystal display device according to claim 1, the width of said red color filters being essentially equal to the width of said blue color filters.

8. The multigap liquid crystal display device according to claim 7:

a) a plurality of thin film transistors, one thin film transistor corresponding to each said picture element electrode being formed on the periphery of said mesh pattern;

b) the thickness of said red color filters (tr), the thickness of said green color filter (tg), and the thickness of said blue color filter (tb) being such that tr<

tg<

tb;

c) said common electrode substrate covering the red, green, and blue color filters over essentially the entire surface area of said glass substrate on which said red, green, and blue color filters are formed;

d) said TFT array substrate and said common electrode substrate being separated by spacers and disposed in close proximity to each other in an opposing manner, with liquid crystal filling the space between said TFT array substrate and said common electrode substrate; and

e) said blue color filters being small enough in width that they do not overlap either said source bus or said gate bus surrounding opposing said picture element electrodes; and

f) said green color filters being large enough in width that they overlap the pairs of source buses and the pairs of gate buses surrounding the opposing picture element electrodes.

9. The multigap liquid crystal display device according to claim 1, said red color filters being formed in close proximity to said blue color filters and to said green color filters, the width of said red color filters being larger than the width of said blue color filters.

10. The multigap liquid crystal display device according to claim 9:

a) a plurality of thin film transistors, one thin film transistor corresponding to each said picture element electrode being formed on the periphery of said mesh pattern;

b) the thickness of said red color filters (tr), the thickness of said green color filter (tg), and the thickness of said blue color filter (tb) being such that tr<

tg<

tb;

c) said common electrode substrate covering the red, green, and blue color filters over the entire surface area of said glass substrate on which said red, green, and blue color filters are formed;

d) said TFT array substrate and said common electrode substrate being separated by spacers and disposed in close proximity to each other in an opposing manner, with liquid crystal filling the space between said TFT array substrate and said common electrode substrate;

e) said blue color filters being small enough in width that said blue color filters do not overlap either said source bus or said gate bus surrounding opposing said picture element electrodes; and

f) said green color filters being large enough in width that said green color filters overlap the pairs of source buses and the pairs of gate buses surrounding the opposing picture element electrodes.

11. A liquid crystal display device comprising in combination:

a) a thin film transistor (TFT) array substrate comprising a plurality of buses;

b) picture element electrodes formed on said TFT array substrate between said buses;

c) a common electrode substrate disposed in close proximity to said TFT array substrate, on which said common electrode substrate are formed a plurality of color filters comprising at least 2 different colors including a plurality of first color filters and a plurality of second color filters;

d) said first color filters being small in width such that when viewed from a location perpendicular to said common electrode substrate, said first color filters do not overlap said buses surrounding the opposing said picture element electrodes; and

e) said second color filters being wide such that when viewed from a location perpendicular to said common electrode substrate, said second color filters overlap said buses surrounding the opposing said picture element electrodes.

12. The device according to claim 11, the film thickness of said buses, the thickness of said first color filters, and the thickness of said second color filters being selected such that the distance between opposing said second color filters and said buses is approximately equal to the distance between the opposing said first color filters and said picture element electrodes.

13. The multigap liquid crystal display device according to claim 12, said TFT array substrate and said common electrode substrate being separated by spacers, with liquid crystal filling the space between said TFT array substrate and said common electrode substrate.

14. The device according to claim 13:

a) said buses comprising source buses and gate buses;

b) said source buses and said gate buses being disposed approximately on a single plane and intersecting each other forming a net-like pattern of meshes; and

c) further comprising thin film transistors.

15. The device according to claim 14:

a) said first color filters comprising blue color filters; and

b) said second color filters comprising green color filters.

16. The device according to claim 15:

a) said color filters further comprising red color filters;

b) the thickness of said red color filters being less than the thickness of said green color filters; and

c) the thickness of said green color filters being less than the thickness of said blue color filters.

17. The device of claim 16, each said red color filter having a width approximately equal to the width of each said blue color filter.

18. The device of claim 17, each said red color filter having a width that is larger than the width of each said blue color filter.

19. The device of claim 18, each said red color filter extending to the proximity of the adjacent said blue color filter.

20. A method of reducing display non-uniformity in a multigap liquid crystal display of the type having:

a thin film transistor (TFT) array substrate including a plurality of buses and a plurality of picture element electrodes, and a common electrode substrate disposed in close proximity to the TFT array substrate, the common electrode substrate having a plurality of first color filters, and a plurality of second color filters;

said method comprising the steps of;

a) selecting the width of the first color filters to be small enough that the first color filters do not overlap the buses;

b) selecting the width of the second color filters to be large enough that the second color filters overlap the buses;

c) selecting the film thickness of the buses, the thickness of the first color filters, and the thickness of the second color filters such that the distance between opposing second color filters and the buses is approximately equal to the distance between the opposing first color filters and the picture element electrodes; and

d) installing spacers between the TFT array substrate and the common electrode substrate.

21. The method according to claim 20:

a) said multigap liquid crystal display further comprising a plurality of third color filters; and

b) said method further comprising the step of selecting the width of the third color filters such that the third color filters each extend to the proximity of the adjacent first color filter.