Multilayer antistatic/antireflective coating for display device

• US 5,652,477 A
• Filed: 11/08/1995
• Issued: 07/29/1997
• Est. Priority Date: 11/08/1995
• Status: Expired due to Fees

• Current Assignee: Chunghwa Picture Tubes Limited
• Original Assignee: Chunghwa Picture Tubes Limited
• Inventors: Hsu, Mi-Yui, Hu, Chung-Min, Tong, Hua-Sou
• Primary Examiner(s): BELL, JANYCE A
• Application Number:
  US08/555,515
• Time in Patent Office: 629 Days
• Field of Search: 427/64, 427/68, 427/162, 427/165, 427/240, 427/419.3, 427/126.2, 427/126.3, 427/108, 427/105, 427/106, 313/479, 313/635
• US Class Current: 313/479
• CPC Class Codes: C09K 3/16 Anti-static materials
• CPC Class Codes: H01J 2229/8635 Antistatic shielding
• CPC Class Codes: H01J 2229/8918 by using interference effects
• 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

Abstract

For use on the outer surface of a faceplate of a display device such as of the cathode ray tube (CRT) type, a first inner antistatic layer of Sb--SnO₂ (particle size between 5-20 nm) is applied to a thickness in the range of 200-600 nm. The Sb--SnO₂ layer has a high light refractive index (n₁ =1.8) and also provides an antireflection function. After pre-heating the faceplate to a temperature in the range of 35°-50° C., a second intermediate antireflection layer of colloidal TiO₂ (light refractive index n₂ =2.0 and particle size between 5-50 nm) is applied over the first inner layer to a thickness of 100-200 nm. A third outer antireflection layer is then applied over the intermediate layer in the form of a silica gel coating at a temperature in the range of 35°-45° C. with a thickness in the range of 100-200 nm and a light refractive index n₃. The second and third antireflective layers follow the 1/4 wavelength rule, where n₃ ≃√n₂ . The multilayer antireflective coating may also be employed in a five layer coating, where the TiO₂ and silica gel layers are repeated in proceeding outward from the glass substrate to provide a wideband antireflection capability.

Claims

1. A video display device comprising a structure having thereon a coating comprising:

a first conductive grounded inner layer disposed on the outer surface of said display panel, said first inner layer having a light refractive index n₁ ;

a second antireflective layer disposed on said first inner layer, wherein said second layer has a light refractive index n₂, wherein n₂ >

n₁ ; and

a third antireflective layer disposed on said second antireflective layer, wherein said third antireflective layer has a light refractive index n₃, wherein n₃ ≃

√

n₂ .

2. The video display device of claim 1 wherein said first inner layer is comprised of antimony-doped tin oxide (Sb--SnO₂) and said second antireflective layer as comprised of titanium oxide (TiO₂).

3. The video display device of claim 2 wherein said third antireflective layer is comprised of silica gel.

4. The video display device of claim 3 wherein said antimony-doped tin oxide layer is 200-600 nm thick and is comprised of particles 5-20 nm in diameter.

5. The video display device of claim 3 wherein said titanium oxide layer is 100-200 nm thick and is comprised of particles 5-50 nm in diameter.

6. The video display device of claim 3 wherein said silica gel layer is 100-200 nm thick.

7. The video display device of claim 1 further comprising a fourth antireflective layer disposed on said third antireflective layer and a fifth antireflective layer disposed on said fourth antireflective layer, wherein said fourth and fifth antireflective layers have the same composition and light refractive indices as said second and third antireflective layers, respectively.

8. The video display device of claim 7 wherein said first inner layer is antimony-doped tin oxide (Sb--SnO₂), said second and fourth antireflective layers are titanium oxide (TiO₂), and said third and fifth antireflective layers are silica gel.

9. A method for applying a multilayer coating to the outer surface of a video display panel by means of spin coating, said method comprising the steps of:

depositing a first conductive antistatic layer on the outer surface of said video display panel, said first antistatic layer having a light refractive index n₁ ;

connecting said first conductive antistatic layer to neutral ground;

depositing a second antireflective layer on the first antistatic layer, said second antireflective layer having a light refractive index n₂, where n₂ >

n₁ ; and

depositing a third antireflective layer on the second antireflective layer, said third antireflective layer has a light refractive index n₃, where n₃ ≃

√

n₂ .

10. The method of claim 9 wherein said first inner layer is antimony-doped tin oxide (Sb--SnO₂), and wherein the step of depositing said first inner layer includes depositing said antimony-doped tin oxide to a thickness in the range of 200-600 nm with a particle size in the range of 5-20 nm.

11. The method of claim 9 wherein said second antireflective layer is titanium oxide, and wherein said titanium oxide is deposited to a thickness in the range of 100-200 nm and is comprised of particles 5-50 nm in diameter.

12. The method of claim 9 wherein said third antireflective layer is comprised of silica gel, and wherein said silica gel is deposited to a thickness in the range of 100-200 nm.