Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Light polarizing article or holographic article
Reexamination Certificate
1999-09-14
2001-11-20
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Light polarizing article or holographic article
C156S275500, C156S275700, C264S001360, C264S001700, C264S313000, C264S571000, C425S127000, C425S174400, C425S808000
Reexamination Certificate
active
06319433
ABSTRACT:
FIELD OF THE INVENTION
The present invention is concerned with the production and/or modification of plastic/plastic or plastic/glass laminate lenses by a process of casting a “wafer” lens to a base lens by way of a curing process, the base lens is usually a prescription lens. Conventionally, such lenses are made by a process involving (a) determining the curvature of the base lens, selecting a wafer lens having a conforming curvature, and (c) adhering the mating surfaces to each other. The present invention overcomes the requirement for stocking a full set of wafer lenses of various curvatures. The invention is a remolding system based on the discovery of two processes. The first discovery is the creation of a wafer lens by a vacuum remolding process. The second discovery is the creation of a wafer lens by a rigid remolding process. In the vacuum molding process, the curvature of a given flexible mold, with the negative impression of a progressive, can be satisfactorily deformed by a vacuum process to match the convex curve of the base lens. The deformed flexible mold has an amount of monomer placed in the negative impression/recess and along the upper surface. A base lens is seated in the monomer, and the monomer cures while the flexible mold is in the deformed state, producing an optical quality lens with no noticeable distortion. In the rigid remolding process, a stock lens and mold lens, with matching concave curvatures pre-determined by the prescription, are selected. The convex surface of the stock lens is placed in the concave surface of the mold lens. The pair of lenses are spaced apart to create a cavity. Monomer is injected into the cavity and cured within the cavity to create an optical quality lens with no noticeable distortion. Accordingly, it is now necessary to only stock flexible molds with a variety of curvatures, such as a 6 base curve, in order to be able to modify any curvature base lens when following the procedure according to the present invention; eliminating the need to stockpile a traditional complete selection of wafer lenses covering the range of available curvatures.
The invention makes it possible to quickly (in a matter of minutes), and inexpensively, create bifocal progressive prescriptions from stock lenses. The invention further makes it possible to convert a stock prescription or non-prescription lens into a photochromic or a tinted photochromic non-prescription (e.g., sunglasses, safety glasses, reading glasses, etc.), prescription, multi-focal or progressive plastic or glass optical quality eyeglass. The invention further makes it possible to modify the prescription of lenses taken directly from the lens frames of a client. The invention further concerns lenses produced by the method wherein the monomer used to form the wafer lens and adhere the wafer lenses to the prescription lens includes photochromic pigments, thereby producing photochromic lenses. Photochromic lenses produced by this process are characterized by an extremely rapid photochromic response. Finally, the invention makes it possible to convert stock Polaroid lenses into non-prescription/prescription multi-focal or progressive and photochromic plastic or glass optical quality lenses.
BACKGROUND OF THE INVENTION
On-site production of prescription lenses is currently on the rise. Advances have recently been made on two fronts in materials and methods for the on-site production of prescription lenses: advances designed to reduce the amount of stock materials which must be carried on site, and advances in reduction of the time needed to produce the prescription lenses. However, none of these approaches has made it possible to eliminate the need to carry wafer lens for adhesion to base lens. Further, no approach has made it possible to transform stock prescription lenses to lenses of different prescriptions or to bifocals or multi-focal lenses in a matter of minutes, including the option of rendering the lenses photochromic. Further, none of the available methods permits the lens crafter to utilize a flexible mold and monomer to form a simple wafer lens onto stock lenses during a curing process, yet offer a wide variety of photochromic properties, tinting, UV protection, scratch resistance, and other desirable properties.
More specifically, one approach to on-site custom lens production involves casting an additional plastic layer onto a plastic lens blank. See, for example, in U.S. Pat. No. 2,339,433 (Staehle) disclosing a method of adding a correction to a molded plastic lens by adding a thin level of resin. U.S. Pat. No. 3,248,460 also discloses means for casting plastic lenses from thermosetting or thermoplastic materials wherein a plastic blank having significantly less curvature than required for the full-intended prescription of the lens is used as a base. An additional layer of material is cast onto this base. The patent employs a conventional optical gasket to provide space between the plastic blank and the mold and to hold the resin material in the cavity created thereby. The additional layer of material changes the curvature of the resulting lens over the vast majority of its surface, thereby changing the prescription of the resulting finished lens to the power required. A disadvantage of this system is that the material must be cured by heat. Such a heat curing process requires heating over a period of more than 12 hours, thus making the formation of the lens a long, drawn-out process. A further obvious disadvantage is that photochromic lenses could not be produced from such materials and methods. Others have tried to manufacture multi-focal or progressive plastic lenses using a lamination technique. Such a technique joins a preformed plastic section, generally referred to as a wafer or wafer lens or veneer lens, to another cured plastic prescription lens. In all cases, the curvature of the wafer lens must correspond to the mating curvature of the base lens, and, thus, the number of wafer lenses which must be maintained in stock corresponds to (a) the number of base lens curvatures to be matched times, (b) the strengths of the corrections times, and (c) the various strengths of progressive or bifocal prescriptions [i.e., (a) x (b) x (c)]. A base lens is matched to a preformed wafer section defining a multi-focal or progressive region and the conforming mating surfaces of these lenses are joined by an adhesive. See, for example, U.S. Pat. No. 4,940,205 (Rudd, et al.) teaching a method and apparatus for forming a laminated bifocal lens which includes selecting a frontal lens component having a bifocal element and bonding the frontal lens component to a rear lens component. The non-prescription frontal lens carrying the bifocal element is referred to as a veneer lens, and the rear lens is referred to as the prescription lens. The arced inner surface of the veneer lens meniscus has the same curvature as the front surface of the prescription lens. To fill a prescription, a technician matches the desired frontal lens with a rear lens carrying the desired prescription base. The adhesive for bonding the two lens components is the same monomer used to cast the lens components. Accordingly, the curvature of the veneer lens must match that of the prescription lens, and no provision is made for incorporation of photochromic pigments.
As a somewhat different approach, see also U.S. Pat. No. 5,433,810 (Abrams) teaching a method and apparatus for lamination of composite eyeglass lenses. Front and rear lenses are laminated together by holding the front lens in an XY adjustable stage on a laminating axis, holding the rear lens in a pre-determined position relative to the laminating axis, and moving the two lenses together on the laminating axis to spread an adhesive between them. Then, the adhesive between the pressed-together lenses is cured by UV radiation directed through the front lens before the lenses are removed from the laminator. The bonding process involves placing a curable adhesive on the concave interface surface of the front lens; pressing the convex interface
Invicta Corporation
Proskauer Rose LLP
Vargot Mathieu D.
LandOfFree
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