Title of Invention

SCRATCH RESISTANT ANT COATED PLASTIC OPHTHALMIC LENSES AND A METHOD OF ITS MANUFCATURE

Abstract

ABSTRACT A method of manufacture of scratch resistant coated plastic ophthalmic lenses comprising the steps of -5 evacuating a chamber to 4.0 - 6.2 x 10 milli Bar vacuum pressure; letting in oxygen into the chamber so that the chamber pressure rises to 0.0008 - 0.001 milli Bar; letting in argon into the chamber so that the chamber pressure further rises to 0.015 - 0.02 milli Bar; placing at least one lens to be coated on a first support within the chamber; placing, prior to evacuation, the target material consisting of tin doped indium oxide (5% tin + 95% indium by weight) on a second support at a distance of 5.0 - 7.0 cm from the first support;connecting a dc magnetron, to the target (-ve lead to the target and +ve lead grounded) so as to cause sputtering and thus deposit the target material on the lens to provide a coating thereon of the target material, which is both scratch proof and anti-reflecting

Full Text

This invention relates to scratch resistant coated plastic ophthalmic lenses. The main disadvantage of glass lenses is that such lenses are brittle, whereas plastic lenses are not. However, the drawback associated with plastic lenses is that they are highly susceptible to scratches. Scratch resistant plastic lenses are. known to the art. However, the present invention proposes scratch resistant lenses which, during manufacture, simultaneously provide anti-reflection properties on the coatings as well. The method, according to this invention, comprises the steps of evacuating a chamber to 4.0 - 6.2 x 10"5 milli Bar vacuum pressure; letting in oxygen into the chamber so that the chamber pressure rises to 0.0008 - 0.001 milli Bar; letting in argon into the chamber so that the chamber pressure further rises to 0.015 - 0.02 milli Bar; placing at least one lens to be coated on a first support within the chamber; placing, prior to evacuation, the target material consisting of tin doped indium oxide (5% tin + 95% indium by weight) on a second support at a distance of 5.0 - 7.0 cm from the first support;connecting a dc magnetron, to the target (-ve lead to the target and +ve lead grounded) so as to cause sputtering and thus deposit the target material on the lens to provide a coating thereon of the target material, which is both scratch proof and anti-reflecting. This invention will now be described with reference to the accompanying drawings, which illustrate in the single Figure therein an apparatus for carrying out the method of manufacture of the lenses proposed herein. The chamber C is evacuated to 4.0 - 6.2 x 10"5 mill bar vacuum pressure, by the vacuum pump P in order to clean the chamber. Thereafter oxygen is let into the chamber C at X until the chamber pressure rises to 0.0008 - 0.001 m ill Bar. Next, argon is let into the chamber at Y so that the chamber pressure further rises to 0.015 - 0.02 mill Bar. The pressure is indicated by the vacuum gauge G. Thereafter one or more lenses L to be coated are placed on a first support SI within the chamber C. The target material T which is an alloy of tin doped indium oxide (5% tin + 95% indium by weight) is placed, prior to evacuation, on a second support S2 at a distance of 5.0 - 7.0 cm from the first support. A dc magnetron M is connected to the target (-ve lead to the target and +ve lead grounded) so as to cause sputtering resulting in the deposition of a portion of the target material on the lenses to provide a coating thereon of the target material, which is both scratch proof and anti-reflecting. The time of sputtering is about 21 - 25 minutes and this period determines the thickness and quality of the coated lenses. The plasma striking voltage is in the range of 380 - 430 Volts for magnetron power of 34 - 40 watts. The terms and expressions in this specification are of description and not of limitation, as these do not exclude any equivalents of the features illustrated and described, having regard to the scope and ambit of this invention. We Claim: LA method of manufacture of scratch resistant coated plastic ophthalmic lenses comprising the steps of evacuating a chamber to 4.0 - 6.2 x 10'5 milli Bar vacuum pressure; letting in oxygen into the chamber so that the chamber pressure rises to 0.0008 - 0.001 milli Bar; letting in argon into the chamber so that the chamber pressure further rises to 0.015 - 0.02 milli Bar; placing at least one lens to be coated on a first support within the chamber; placing, prior to evacuation, the target material consisting of tin doped indium oxide (5% tin + 95% indium by weight) on a second support at a distance of 5.0 - 7.0 cm from the first support;connecting a dc magnetron, to the target (-ve lead to the target and +ve lead grounded) so as to cause sputtering and thus deposit the target material on the lens to provide a coating thereon of the target material, which is both scratch proof and anti-reflecting 2. A method as claimed in Claim 1 wherein the sputtering time is 21 - 25 minutes. 3.A method as claimed in Claim 1 or Claim 2 wherein the plasma striking voltage is in the range of 380 - 430 Volts for magnetron power of 34 - 40 watts. 4 A method of manufacture of scratch resistant coated plastic ophthalmic lenses substantially as herein described and illustrated with reference to the accompanying drawings. 5.Scratch resistant coated plastic ophthalmic lenses whenever manufacture by a method as claimed in any one of the preceding Claims.

Documents:

0195-che-2003 abstract.pdf

0195-che-2003 claims duplicate.pdf

0195-che-2003 claims.pdf

0195-che-2003 correspondence others.pdf

0195-che-2003 correspondence po.pdf

0195-che-2003 description (complete) duplicate.pdf

0195-che-2003 description (complete).pdf

0195-che-2003 drawings.pdf

0195-che-2003 form-1.pdf

0195-che-2003 form-19.pdf

0195-che-2003 form-26.pdf