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EP-3765278-B1 - OPTICAL LENS AND METHOD OF COATING AN EDGE SURFACE OF AN OPTICAL LENS

EP3765278B1EP 3765278 B1EP3765278 B1EP 3765278B1EP-3765278-B1

Inventors

  • TAN, MABELINE
  • YU, HUI
  • ANG, Ker Chin
  • Herfort, David

Dates

Publication Date
20260506
Application Date
20190314

Claims (13)

  1. A method of coating an edge surface of an optical lens, the method comprising a) providing an optical lens comprising a first optical surface and an opposing second optical surface, wherein the first optical surface and the second optical surface are connected by an edge surface; b) disposing at least one temporary protective material on at least a portion of a perimeter portion of one or both of the first optical surface and the second optical surface abutting the edge surface, wherein the at least one temporary protective material is selected from the group consisting of a metallic fluoride, a metallic oxide, and a combination thereof; c) disposing at least one coating material on the edge surface of the optical lens to obtain at least one edge coating; and d) removing any excess coating material disposed on the at least one temporary protective material from the one or both of the first optical surface and the second optical surface, e) removing the at least one temporary protective material together with the any excess coating material or after the any excess coating material is removed.
  2. The method according to claim 1, further comprising trimming the edge surface and/or one or both of the first optical surface and the second optical surface of the optical lens according to specific requirements after the at least one temporary protective material is disposed, and before disposing the at least one coating material.
  3. The method according to claim 2, wherein trimming the edge surface and/or one or both of the first optical surface and the second optical surface of the optical lens comprises grinding of a profile of the edge surface.
  4. The method according to any one of claims 1 to 3, wherein disposing the at least one temporary protective material is carried out on only an entire perimeter portion of both the first optical surface and the second optical surface, and is not disposed on portions nearer the central area of the first optical surface and the second optical surface.
  5. The method according to any one of claims 1 to 4, wherein either one or both of disposing the at least one temporary protective material and disposing the at least one coating material are carried out by a method selected from the group consisting of vacuum deposition, vapor deposition, sol-gel deposition, spin coating, dip coating, spray coating, flow coating, film laminating, sticker coating, roller coating, brush coating, painting, sputtering, casting, Langmuir-Blodgett deposition, laser printing, inkjet printing, screen printing, pad printing, and a combination thereof.
  6. The method according to any one of claims 1 to 5, wherein a bonding force between the at least one temporary protective material and the underlying optical surface is smaller than or equal to a bonding force between the at least one temporary protective material and the any excess coating material.
  7. The method according to any one of claims 1 to 6, wherein a bonding force between the any excess coating material and the at least one temporary protective material is smaller than a bonding force between the edge surface and the at least one edge coating.
  8. The method according to any one of claims 1 to 7, wherein the at least one temporary protective material is a combination of a metallic fluoride and a metallic oxide.
  9. The method according to claim 8, wherein the at least one temporary protective material (535) is a mixture of MgO and MgF 2 .
  10. The method according to any one of claims 1 to 9, wherein the at least one coating material is at least one of (a) a material effective to reduce a reflection caused by a profile of the edge surface, (b) a lubricating material effective to ease mounting of the optical lens onto an eyeglass frame, (c) a shock absorbing material effective to reduce stress concentrations on an edge portion of the optical lens, or (d) a material effective to provide an aesthetic effect to the edge surface.
  11. The method according to any one of claims 1 to 10, wherein removing the any excess coating material is carried out by one or all of (a) peeling off the any excess coating material, (b) applying an adhesive tape to the any excess coating material, and removing the adhesive tape, and (c) wipe off the any excess coating material.
  12. An optical lens comprising a first optical surface and an opposing second optical surface, wherein the first optical surface and the second optical surface are connected by an edge surface, the optical lens further comprising: - at least one temporary protective material disposed on only at least a portion of a perimeter portion of one or both of the first optical surface and the second optical surface abutting the edge surface, wherein the at least one temporary protective material is selected from the group consisting of a metallic fluoride, a metallic oxide, and a combination thereof; - at least one coating material disposed on the edge surface of the optical lens, said at least one temporary protective material being adapted to be removed together with any excess coating material disposed on the at least one temporary protective material or after any excess coating material disposed on the at least one temporary protective material is removed.
  13. The optical lens according to claim 12, wherein the at least one coating material is at least one of (a) a material effective to reduce a reflection caused by a profile of the edge surface, (b) a lubricating material effective to ease mounting of the optical lens onto an eyeglass frame, (c) a shock absorbing material effective to reduce stress concentrations on an edge portion of the optical lens, or (d) a material effective to provide an aesthetic effect to the edge surface.

Description

Technical Field This disclosure relates generally to optical lenses, and methods of coating an edge surface of an optical lens. Background A coating material may be introduced on the edge of an optical lens as an edge coating for various reasons. For example, an opaque coating may be deposited on the edge of an optical lens to reduce visibility of "myopia rings" and "white rings" for aesthetic purposes. Examples of a "myopia ring" and a "white ring" are shown in FIG. 1A and FIG. 1B as 110 and 112, respectively. To this end, an operator may apply the coating material on the edge of an optical lens using a marker pen or a brush, or by spray coating. Ideally, the coating material is applied onto the edge surface of the optical lens only, without any of the coating material being coated on the optical surfaces of the optical lens. For illustration purposes, FIG. 2A is a schematic diagram showing an edge coating 202 disposed on an edge surface of an optical lens 200. The edge surface of the optical lens 200 is defined by the surface connecting the first optical surface 220 and the second optical surface 222. The edge surface of the optical lens 200 comprises a lens bevel 226 and a safety bevel 224. As depicted in the figure, there is no overflow on the first optical surface 220 and the second optical surface 222 of the optical lens 200. Notwithstanding the above, the operator often finds himself or herself in a situation whereby he or she accidentally introduces some excess coating, otherwise termed herein as overflow, on the optical surfaces. This is depicted in FIG. 2B, which is a schematic diagram showing an edge coating 202 disposed on an edge surface of an optical lens 200. As shown in the figure, there is overflow in the form of excess coating material 204, 206 disposed respectively on the first optical surface 220 and the second optical surface 222 of the optical lens 200. These overflows have to be removed completely so as not to compromise aesthetics of the optical lens. In embodiments wherein an optical lens edge comprises multiple facets, for example, it is very difficult to ensure complete coating coverage on each and every facet, while not introducing overflows on the optical surfaces. Current methods to remove the overflows are laborious, and quality of the final product varies greatly depending on the skills and craftsmanship of the operator processing them. For example, an operator who attempts to remove the overflow with a solvent, such as acetone or isopropyl alcohol (IPA), often removes a part of the edge coating inadvertently. Therefore, another attempt has to be made to touch up the edge coating. The laborious cycle(s) of overflow removal and touching up of the edge coating may continue until conditions of good cosmetics of the optical lens are met. Based on the above discussion, quality of the final product may rely solely on the dexterity of the operator who is carrying out the overflow removal. This is even more significant for cases where touching up of the edge coating is not possible. Moreover, in embodiments wherein a safety bevel is comprised in the edge surface of an optical lens, a defined breakage between the overflow and the intended edge coating is not achievable using state of the art removal processes. This translates into incomplete removal of overflow from the optical surfaces and is depicted in FIG. 3. As shown in the figure, remnants of coating 304 not removed by the removal process remain as fragments on the optical lens 300, causing bad aesthetics when viewed from the first optical surface or the second optical surface of the optical lens. Other methods to tackle problems with overflow removal include use of ultraviolet (UV) curable coatings and remove the overflow from optical surfaces using suitable sticky tapes. This method has several limitations. For example, specific UV-curable coatings have to be developed such that difference in adhesion of the UV-curable coating with the edge surface and the optical surfaces are large enough, so that the UV-curable coating may be removed from the optical surfaces easily. This in turn limits the choice of suitable lens edge coating materials. In cases of UV-curable coatings which are opaque, UV light is not able to penetrate the opaque coating beyond a certain thickness. Consequently, mechanical strength of the UV-curable coating may be compromised due to insufficient curing of the coating beneath the surface. In light of the above, there remains a need for improved methods which are able to provide a consistent and complete coating coverage on the edge surface of an optical lens, while ensuring absence of the coating material on the optical surfaces, thereby addressing or at least alleviating one or more of the above-mentioned problems. US 2009/141236 A1 discloses a method of coating an edge surface of an optical lens and an optical lens thereof. Summary In a first aspect, a method of coating an edge surface of an optical lens a