Patent EA-003170-B1 (EA)
Title: Method of lens casting without using a gasket
Inventor: SU KAI C
IPC: B29C33/30
Filed: 2000-03-17
Abstract: 1. A method for molding an optical lens without using a gasket, comprising the steps of: a. positioning a front mold and a back mold whose facing inside surfaces are a negative image of the surfaces of the optical lens at a proper distance and rotational orientation to each other, b. wrapping around the edges of the front mold and back mold with a strip to form a sleeve and comprising a longitudinal recess channel on the inside surface forming a molding cavity with the front mold and back mold, the molding cavity in fluid communication with the recess channel; c. injecting a fluid lens-forming material into the molding cavity through the recess channel; and d. curing the fluid lens-forming material to form the optical lens, wherein the sleeve allows the front mold and back mold to slide along at least a portion of the longitudinal axis and the diameter of the sleeve remains substantially constant during the curing of the fluid lens-forming material. 2. The method of claim 1, wherein the strip is made from a nonadhesive plastic film. 3. The method of claim 2, wherein the nonadhesive plastic film comprises an elastomeric material selected from the group of polyurethane, polyvinyl chloride, organosilicon elastomer and thermoplastic rubbers containing a styrene-ethylene-propylene(butylene) block copolymer. 4. The method of claim 2, wherein the thickness of the non-adhesive plastic film is between 1.0 millimeter and 8.0 millimeter. 5. The method of claim 1, further comprising the step of fastening the first and second ends of the strip together to close the molding cavity and to form a tail. 6. The method of claim 5, further comprising the step of using the tail as a handler to handle the molds. 7. The method of claim 1, wherein the step of wrapping comprises the step of wrapping around the edges of the front mold and back mold with the interior surface of the strip in direct contact with the edges of the front mold and back mold. 8. The method of claim 5, further comprising the step of using a port, which is formed by the portion of the recess channel at the first end and the portion of the recess channel at the second end after the first end and the second end are fastened together, as a venting channel and a passage for establishing a fluid communication to the molding cavity. 9. A method for producing multiple types and powers of lenses using two molds without a gasket, comprising the steps of: a. positioning the two molds at a desired distance and rotational orientation relative to each other to form a particular lens type and power; b. wrapping an elastomeric strip around the edges of the two molds, comprising a longitudinal recess channel formed on the inside surface and forming a moulding cavity, c. injecting a fluid lens-forming mixture into the cavity through the recess channel; and d. curing the fluid lens-forming material to form a lens with the particular lens type and power. 10. The method of claim 9, further comprising the step of adjusting the positions of the molds by movable vacuum fixtures engaged with the molds. 11. The method of claim 9, wherein the fluid lens-forming mixture is a monomer. 12. The method of claim 9, wherein the step of injecting the fluid lens-forming mixture further comprises the steps of: a. piercing the elastomeric strip by a filling needle so that the filling needle is in fluid communication with the recess channel; and b. injecting the fluid lens-forming mixture into the cavity through the filling needle. 13. The method of claim 9, wherein the step of wrapping comprises the step of wrapping around the edges of the two molds with the interior surface of the strip in direct contact with the edges of the two molds. 14. The method of claim 9, further comprising, after the step of curing the fluid lens-forming mixture, the step of separating the elastomeric strip and molds from the lens. 15. The method of claim 9, further comprising the step of fastening the first and second ends of the elastomeric strip together to close the cavity and to form a tail. 16. The method of claim 15, further comprising the step of using the tail as a handler to transfer the molds and the cured fluid lens-forming mixture. 17. An apparatus for molding a lens without using a gasket, comprising: a. a front mold and a back mold, each having a facing inside surface and an edge; b. means for positioning the front mold and the back mold at a desired distance and rotational orientation relative to each other so that the facing inside surfaces of the front mold and the back mold are a negative image of the surfaces of the lens; and c. a strip for wrapping around the edges of the front mold and the back mold to form a sleeve, and comprising a longitudinal a recess channel formed on the interior surface to form a molding cavity, the molding cavity being in fluid communication with the recess channel. 18. The apparatus of claim 17, wherein the strip is made from a plastic film. 19. The apparatus of claim 18, wherein the plastic film is nonadhesive. 20. The apparatus of claim 18, wherein the plastic film comprises an elastomeric material selected from the group of polyurethane, polyvinyl chloride, organosilicon elastomer and thermoplastic rubbers containing a styrene-ethylene-propylene (butylene) block copolymer. 21. The apparatus of claim 18, wherein the thickness of the plastic film is between 1.0 millimeter and 8.0 millimeter.