Method of separating excess lens forming material from a molded ophthalmic lens, in particular a contact lens
View Patent ↗There is described a method of separating excess lens forming material from a molded ophthalmic lens, in particular a contact lens. After polymerization and/or cross-linking of a lens forming material (P) within a mold cavity ( 4 ) of a mold ( 1 ) comprising female and male mold halves ( 2, 3 ) to form an ophthalmic lens non-polymerized and/or non-cross-linked lens forming material is flushed away from the mold halves ( 2, 3 ) with a jet of a fluid flushing medium, such as, e.g., water or a solvent or an inert gas. Subsequently the molded lens is dried. In accordance with the invention the flushing is accomplished with the mold halves ( 2, 3 ) still in the closed position. There is also described an apparatus for carrying out the method.
1. A method of separating excess lens forming material from a molded ophthalmic lens, comprising the steps of dosing a lens forming material into a mold cavity of a mold comprising female and male mold halves, applying energy to polymerize and/or crosslink the lens forming material, and then flushing from the mold halves non-polymerized and/or non-cross-linked lens forming material with a jet of a fluid flushing medium, wherein for the flushing of the mold halves the flushing medium is injected into a peripheral zone of the mold cavity through a feed channel, and wherein the flushing medium together with the excess lens forming material is discharged through a discharge channel; and then drying the molded lens by subjecting it to a heated gas stream which is introduced through the feed channel and discharged through the discharge channel, and wherein the step of flushing is accomplished with the mold halves being arranged in a closed position.
2. The method according to claim 1 , wherein the female and male mold halves are axially guided in a guide sleeve and wherein the guide sleeve is provided with feed and discharge ports which communicate with the feed channel and the discharge channel, respectively.
3. The method according to claim 2 , wherein the feed channel and the discharge channel are arranged in vicinity of separation planes of the female and male mold halves.
4. The method according to claim 1 , wherein the feed channel and the discharge channel are arranged such, that the flushing medium is injected through the feed channel into the peripheral zone of the mold cavity substantially tangentially, and after being guided around the peripheral zone is discharged into the discharge channel at an opposite circumferential portion of the mold cavity.
5. The method according to claim 4 , wherein the flushing medium is injected and discharged in directions which extend generally parallel to each other.
6. The method according to claim 1 , wherein the flushing medium is selected from the group consisting of air, inert gas, water and isopropanol.
7. The method according to claim 1 , wherein after the drying of the molded lens the discharge channel through which the heated gas stream is discharged, is closed and subsequently the mold is opened by moving the female and male mold halves away from each other.