Liquid crystal display apparatus and method for producing TFT using therefor

• US 6,335,779 B1
• Filed: 09/19/2000
• Issued: 01/01/2002
• Est. Priority Date: 01/27/1999
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Advanced Display Technologies, Mistubishi Denki Kaubshiki Kaisha
• Inventors: Tamatani, Akira, Matsukawa, Fumio, Tahata, Shin, Morii, Yasuhiro, Fujii, Masayuki, Fujita, Yasuo, Tsumura, Akira, Mizunuma, Masaya
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/665,052
• Time in Patent Office: 469 Days
• Field of Search: 349/141, 349/155, 349/156, 349/153, 349/187, 349/106, 349/109
• US Class Current: 349/155
• CPC Class Codes: G02F 1/133357 Planarisation layers
• CPC Class Codes: G02F 1/13392 spacers dispersed on the cell substrate, e.g. spherical particles, microfibres
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]

Abstract

A method of manufacturing an in-plane switching liquid crystal display apparatus which includes forming on a TFT array substrate, a plurality of scanning signal lines, a plurality of image signal lines each crossing the scanning signal lines, thin film transistors at each intersection of the scanning signal lines and image signal lines, liquid crystal driving electrodes opposing the liquid crystal driving electrodes, and common signal lines connected to the common electrodes. Further, the method includes opposing a counter substrate to the TFT array substrate, interposing a plurality of spacers in a gap between the TFT array substrate and the counter substrate, and interposing a sealing agent in the gap between the TFT array substrate and the counter substrate so as to adhere the TFT array substrate and the counter substrate at peripheral portions thereof. In addition, a liquid crystal layer is pinched and held between the array substrate and the counter substrate and which presents birefringence effects, and a manufactured in-plane switching liquid crystal display apparatus with a difference in transmittance of more than 5% for green light of approximately 544 nm wavelength in a displaying area of the in-plane switching liquid crystal display apparatus is rejected.

Claims

1. A method of manufacturing an in-plane switching liquid crystal display apparatus, comprising:

forming on a TFT array substrate, a plurality of scanning signal lines, a plurality of image signal lines each crossing the scanning signal lines, thin film transistors at each intersection of the scanning signal lines and image signal lines, liquid crystal driving electrodes connected to the thin film transistors, common electrodes opposing the liquid crystal driving electrodes, and common signal lines connected to the common electrodes;

opposing a counter substrate to the TFT array substrate;

interposing a plurality of spacers in a gap between the TFT array substrate and the counter substrate;

interposing a sealing agent in the gap between the TFT array substrate and the counter substrate so as to adhere the TFT array substrate and the counter substrate at peripheral portions thereof;

providing a liquid crystal layer pinched and held between the array substrate and the counter substrate and which presents birefringence effects; and

rejecting the manufactured in-plane switching liquid crystal display apparatus if a difference in transmittance of more than 5% for green light of approximately 544 nm wavelength in a displaying area of the in-plane switching liquid crystal display apparatus occurs,

wherein an in-plane retardation of the display apparatus (Δ

n)·

(d_max−

d_min) is not less than 0 nm and not more than 20 nm in a case a largest gap of gaps between the liquid crystal driving electrodes and opposing substrates within the display surface of the liquid crystal display is denoted d_max, and a smallest gap within the display surface of the liquid crystal display is denoted d_min.

2. The method according to claim 1, further comprising:

forming an organic film on the TFT array substrate with a thickness of not less than 3 μ

m and not more than 10 μ

m.

3. The method according to claim 2, wherein the liquid crystal driving electrodes and common electrodes are formed on the organic film.

4. The method according to claim 2, wherein in a case uneveness of an in-plane film of the organic film parallel to the TFT array substrate is expressed as concave portions and convex portions, an absolute value for a height obtained by subtracting a respective concave portion from a respective convex portion is not more than 0.4 μ

m.

5. The method according to claim 2, further comprising:

applying organic resin having a viscosity of not less than 15 cP and not more than 50 cP onto a surface of the TFT array substrate by spin coating at a rotational speed of not less than 500 rpm and not more than 2,000 rpm, such that the organic film is formed as a flatting film.

6. The method according to claim 5, wherein the organic resin is selected from the group consisting of a photosensitive acrylic resin and an acrylic resin.

7. The method according to claim 5, wherein a thickness of the flatting film is set to be not less than 3 μ

m and not more than 10 μ

m.

8. The method according to claim 1, wherein the plurality of spacers comprise a plurality of primary spacers having a spherical shape, and a plurality of secondary spacers having a columnar shape.

9. The method according to claim 8, wherein a diameter of the secondary spacers is a sum of a thickness of a coloring layer provided on the counter substrate and of a diameter of the primary spacers.

10. A method of manufacturing an in-plane switching liquid crystal display apparatus, comprising:

forming on a TFT array substrate, a plurality of scanning signal lines, a plurality of image signal lines each crossing the scanning signal lines, thin film transistors at each intersection of the scanning signal lines and image signal lines, liquid crystal driving electrodes connected to the thin film transistors, common electrodes opposing the liquid crystal driving electrodes, and common signal lines connected to the common electrodes;

opposing a counter substrate to the TFT array substrate;

interposing a plurality of spacers in a gap between the TFT array substrate and the counter substrate;

interposing a sealing agent in the gap between the TFT array substrate and the counter substrate so as to adhere the TFT array substrate and the counter substrate at peripheral portions thereof;

providing a liquid crystal layer pinched and held between the array substrate and the counter substrate and which presents birefringence effects;

forming an organic film on the TFT array substrate with a thickness of not less than 3 μ

m and not more than 10 μ

m; and

rejecting the manufactured in-plane switching liquid crystal display apparatus if a difference in transmittance of more than 5% for green light of approximately 544 nm wavelength in a displaying area of the in-plane switching liquid crystal display apparatus occurs.

11. The method according to claim 10, wherein the liquid crystal driving electrodes and common electrodes are formed on the organic film.

12. The method according to claim 10, wherein in a case uneveness of an in-plane film of the organic film parallel to the TFT array substrate is expressed as concave portions and convex portions, an absolute value for a height obtained by subtracting a respective concave portion from a respective convex portion is not more than 0.4 μ

m.

13. The method according to claim 10, wherein the plurality of spacers comprise a plurality of primary spacers having a spherical shape, and a plurality of secondary spacers having a columnar shape.

14. The method according to claim 13, wherein a diameter of the secondary spacers is a sum of a thickness of a coloring layer provided on the counter substrate and of a diameter of the primary spacers.

15. The method according to claim 10, further comprising:

applying organic resin having a viscosity of not less than 15 cP and not more than 50 cP onto a surface of the TFT array substrate by spin coating at a rotational speed of not less than 500 rpm and not more than 2,000 rpm, such that the organic film is formed as a flatting film.

16. The method according to claim 15, wherein the organic resin is selected from the group consisting of a photosensitive acrylic resin and an acrylic resin.

17. The method according to claim 15, wherein a thickness of the flatting film is set to be not less than 3 μ

m and not more than 10 μ

m.