Anti-static, anti-reflection coating
View Patent ↗An anti-static, anti-reflection, transparent coating for a transpatent substrate, the coating including at least one electrically conductive layer, wherein the sheet resistance of the coating is less than about 10 10 ohm/square. The coating is preferably higher transparent.
1. An anti-static, anti-reflection, transparent coating for a transparent ophthalmic lens, the coating including at least one electrically conductive layer, wherein the sheet resistance of the coating is between about 10 7 ohm/square to about 10 10 ohm/square and the luminous transparency of the ophthalmic lens, when coated on both sides with the coating, is greater than about 95% and the luminous absorption due to the coating is less than about 1%.
2. A coating according to claim 1 , wherein the ophthalmic lens is made from a material that is selected from the group consisting of glass, crystalline quartz, fused silica, soda-lime silicate glass, and plastic.
3. A coating according to claim 2 , wherein the plastic is a polymer based on allyl diglycol carbonate monomers or a polycarbonate.
4. A coating according to claim 1 , the coating including from 2 to 12 layers, at least one of which is the electrically conductive layer.
5. A coating according to claim 4 , the coating including from 2 to 7 layers, at least one of which is the electrically conductive layer.
6. A coating according to claim 1 , the coating having a thickness of from about 100 to 750 nm.
7. A coating according to claim 6 , the coating having a thickness of from about 220 to 500 nm.
8. A coating according to claim 1 , wherein the electrically conductive layer has a thickness of from 0.1 to 150 nm.
9. A coating according to claim 8 , wherein the electrically conductive layer has a thickness of from 1 to 5 nm.
10. A coating according to claim 1 , wherein the electrically conductive layer comprises a material that is selected from the group consisting of indium oxide, tin oxide, zinc oxide, and mixtures thereof.
11. A coating according to claim 1 , wherein the electrically conductive layer contains a dopant to increase conductivity without altering optical transparency.
12. A coating according to claim 11 , wherein the dopant is selected from the group consisting of fluorine, antimony, aluminum, boron, phosphor, iridium and mixtures thereof.
13. A coating according to claim 1 , the coating being a three layer coating and having a lower layer of a mid-refractive index material, an intermediate layer of a high refractive index material, and an upper layer of a low refractive index material.
14. A coating according to claim 13 , wherein the mid-refractive index material is silicon oxynitride.
15. A coating according to claim 13 , wherein the intermediate layer is the electrically conductive layer.
16. A coating according to claim 13 , wherein the low refractive index material is silicon dioxide.
17. A coating according to claim 1 , the coating being a seven layer coating, having an adhesion layer of chrome oxide, subsequent alternating layers of low and high refractive index materials, and an outer layer of a low refractive index material, with the electrically conductive layer being between the adhesion layer and the outer layer.
18. A coating according to claim 17 , wherein the electrically conductive layer is indium tin oxide.
19. A coating according to claim 17 , wherein the low refractive index material is silicon dioxide.
20. A coating according to claim 17 , wherein the high refractive index material is titanium dioxide or zirconium oxide.
21. An ophthalmic lens having an anti-static, anti-reflection transparent coating, the coating including at least one electrically conductive layer, wherein the sheet resistance of the coating is between about 10 7 ohm/square to about 10 10 ohm/square and the luminous transparency of the ophthalmic lens, when coated on both sides with the coating, is greater than about 95% and the luminous absorption due to the coating is less than about 1%.
22. An ophthalmic lens according to claim 21 , wherein the coating includes from 2 to 12 layers, at least one of which is the electrically conductive layer.
23. An ophthalmic lens according to claim 21 , wherein the coating includes from 3 to 7 layers, at least one of which is the electrically conductive layer.
24. An ophthalmic lens according to claim 23 , wherein the electrically conductive layer has a thickness of from 0.1 to 150 nm.
25. An ophthalmic lens according to claim 21 , wherein the coating has a thickness of from 220 to 500 nm.
26. An ophthalmic lens according to claim 21 , wherein the electrically conductive layer comprises a material that is selected from the group consisting of indium oxide, tin oxide, zinc oxide, and mixtures thereof.
27. An ophthalmic lens according to claim 21 , wherein the electrically conductive layer contains a dopant to increase conductivity without altering optical transparency.
28. An ophthalmic lens according to claim 27 , wherein the dopant is selected from the group consisting of fluorine, antimony, aluminum, boron, phosphor, indium, and mixtures thereof.
29. An ophthalmic lens according to claim 21 , wherein the coating is a three layer coating having a lower layer of a mid refractive index material, an intermediate layer of a high refractive index material, and an upper layer of a low refractive index material.
30. An ophthalmic lens according to claim 29 , wherein the mid-refractive index material is silicon oxynitride.
31. An ophthalmic lens according to claim 29 , wherein the intermediate layer is the electrically conductive layer.
32. An ophthalmic lens according to claim 29 , wherein the low refractive index material is silicon dioxide.
33. An ophthalmic lens according to claim 21 , the coating being a seven layer coating, having an adhesion layer of chrome oxide, subsequent alternating layers of low and high refractive index materials, and an outer layer of a low refractive index material, the electrically conductive layer being between the adhesion layer and the outer layer.
34. An ophthalmic lens according to claim 21 , wherein the electrically conductive layer is indium tin oxide.
35. An ophthalmic lens according to claim 33 , wherein the low refractive index material is silicon dioxide.
36. An ophthalmic lens according to claim 33 , wherein the high refractive index material is titanium dioxide or zirconium oxide.
37. A method of fabricating a transparent ophthalmic lens, the method including the steps of:
providing a transparent ophthalmic lens; and
forming on a surface of the ophthalmic lens an anti-static, anti-reflection transparent coating having at least one electrically conductive layer, such that the sheet resistance of the coating is between about 10 7 ohm/square to about 10 10 ohm/square and the luminous transparency of the ophthalmic lens, when coated on both sides with the coating, is greater than about 95% and the luminous absorption due to the coating is less than about 1%.
38. A method according to claim 37 , wherein the coating is deposited on the lens by reactive sputtering deposition.
39. A method according to claim 38 , wherein the reactive sputtering deposition comprises sputtering of a metallic target in a gas phase composition.
40. A method according to claim 39 , wherein the gas phase composition is an argon-oxygen mixture.
41. A method according to claim 39 , wherein the metallic target is an indium-tin target.
42. A method according to claim 40 , wherein the ratio of the partial pressure of argon to the partial pressure of oxygen in the argon-oxygen mixture during sputtering reaches up to about 0.15.
43. A method according to claim 39 , wherein the target is maintained at a relatively constant voltage during deposition.
44. A method according to claim 38 , wherein reactive sputtering deposition comprises sputtering of a target made of an electrically conductive material in a gas phase composition.
45. A method according to claim 44 , wherein the gas phase composition includes oxygen.
46. A method according to claim 37 , wherein the coating is deposited on the ophthalmic lens by the evaporation of a source material in a gas phase.
47. A method according to claim 46 , wherein the gas phase is an argon-oxygen gas mixture.
48. A method according to claim 46 , wherein the source material for the electrically conductive layer is selected from the group consisting of indium oxide, tin oxide and doped zinc oxide.
49. A method according to claim 48 wherein the dopant is selected from the group consisting of aluminum, boron, phosphor, indium, and mixtures thereof.
50. A method according to claim 46 , wherein evaporation is assisted by providing the source material with extra energy.
51. A method according to claim 50 , wherein the extra energy is from an ion or neutral atom beam source.
52. A method according to claim 46 , wherein the electrically conductive layer is deposited under a partial pressure of oxygen of between 1.5×10 −4 mbar and 5×10 −4 mbar.
53. A method according to claim 52 , wherein the partial pressure of oxygen is between 1.5×10 −4 mbar and 5×10 −4 mbar.
54. A method according to claim 46 , wherein, during deposition of the electrically conductive layer the evaporation rate is between 0.01 nm/sec and 2 nm/sec.
55. A method according to claim 54 , wherein the evaporation rate is between 0.01 nm/sec and 0.5 nm/sec.