Carbon black coating for CRT display screen with uniform light absorption

• US 6,623,662 B2
• Filed: 05/23/2001
• Issued: 09/23/2003
• Est. Priority Date: 05/23/2001
• Status: Expired due to Term

• Current Assignee: CPT Technology (Group) Co., Ltd.
• Original Assignee: Chunghwa Picture Tubes Limited
• Inventors: Hu, Chun-Min, Wang, Kuo-Chu
• Primary Examiner(s): Gupta, Yogendra N.
• Assistant Examiner(s): VIJAYAKUMAR, KALLAMBELLA M
• Application Number:
  US09/864,063
• Publication Number:
  US 20020175315A1
• Time in Patent Office: 853 Days
• Field of Search: 252/518.1, 252/520.1, 252/520.21, 423/87, 423/89, 423/335, 423/339, 423/617, 423/618, 423/624, 106/316, 106/445, 106/455, 428/331, 428/357, 428/379, 428/402, 313/364, 313/479, 427/68, 427/164, 427/122
• US Class Current: 252/502
• CPC Class Codes: H01J 2229/8632 characterised by the material
• CPC Class Codes: H01J 2229/8635 Antistatic shielding
• CPC Class Codes: H01J 2229/8913 Anti-reflection, anti-glare, viewing angle and contrast improving treatments or devices
• CPC Class Codes: H01J 29/327 Black matrix materials
• CPC Class Codes: H01J 29/868 Screens covering the input or output face of the vessel, e.g. transparent anti-static coatings, X-ray absorbing layers
• CPC Class Codes: H01J 9/2278 Application of light absorbing material, e.g. between the luminescent areas
• CPC Class Codes: Y10T 428/259 Silicic material
• CPC Class Codes: Y10T 428/29 Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
• CPC Class Codes: Y10T 428/2942 Plural coatings

Abstract

A two-layer coating for the outer surface of the display screen of a color cathode ray tube (CRT) includes an inner carbon black-based layer and an outer silica-based layer. The inner layer is antistatic, while the outer layer is antireflective. To compensate for the increased absorption of blue light by the carbon black particles, which results in a color video image having a yellowish tint, a blue additive, such as a pigment or dye, is added to the coating to adjust its light absorbance characteristics and provide uniform light absorbance over the entire visible spectrum of 400-700 nm for improved color video image presentation.

Claims

1. An electrically conductive coating for an outer surface of a glass display screen of a self-emitting display device, wherein said glass display screen further includes a phosphor coating on an inner surface thereof, and wherein said phosphor coating is responsive to energetic electrons incident thereon for providing a video image, said coating comprising:

a thin layer of a solution of carbon black particles having a black appearance and disposed on the outer surface of the device'"'"'s glass display screen;

a blue additive dispersed in said carbon black solution to reduce absorbance of blue light by the carbon black and provide substantially uniform color absorption by said carbon black solution over the visible light spectrum, wherein said blue additive reduces the absorbance of light having a wavelength in the range of 400-500 nm and has a weight % relative to said carbon black particles of 5-60% and

an antireflective layer disposed on said thin layer of carbon black solution.

2. The coating of claim 1 wherein said blue additive is a dye or pigment.

3. The coating of claim 1 further comprising indium-doped tin oxide.

4. The coating of claim 1 further comprising antimony-doped tin oxide.

5. The coating of claim 1 wherein said antireflective layer includes silica.

6. The coating of claim 1 wherein said blue additive is Cu-phthalocyanine.

7. The coating of claim 1 having a thickness on the order of 0.1 micron.

8. An ant static/antireflective coating for the outer surface of a display screen of a self-emitting color display device whereon is presented a color video image, said antistatic/antireflective coating comprising:

a thin antistatic layer of a solution containing carbon black particles disposed on the outer surface of the display screen, wherein said solution containing carbon black particles is black in appearance for improved video image contrast and is electrically conductive for discharging an electrostatic charge on the display screen to neutral ground and providing an electrostatic shield for the display device;

an antireflective layer disposed on said antistatic layer; and

a blue additive dispersed in said antistatic layer for reducing absorbance of blue light by said carbon particles and providing substantially uniform color absorption by said antistatic layer over the visible light spectrum, wherein said blue additive reduces the absorbance of light having a wavelength in the range of 400-500 nm and has a weight % relative to said carbon black particles of 5-60%.

9. The antistatic/antireflective coating of claim 8 wherein said blue additive is a dye or pigment.

10. The antistatic/antireflective coating of claim 8 wherein said antistatic layer further includes indium-doped tin oxide.

11. The antistatic/antireflective coating of claim 8 wherein said antistatic layer further includes antimony-doped tin oxide.

12. The antistatic/antireflective coating of claim 8 wherein said blue additive is Cu-phthalocyanine.

13. The antistatic/antireflective coating of claim 8 having a thickness on the order of 0.1 micron.

14. The antistatic/antireflective coating of claim 8 wherein said antireflective layer includes silica.