Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
1999-10-22
2001-12-11
Epps, Georgia (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S165000, C428S411100
Reexamination Certificate
active
06328446
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical elements and to methods of making optical elements. More specifically, the present invention relates to an optical element that incorporates a laminate to provide a functional property and to a method of incorporating the functional property in the optical element by adherence of the laminate to an optical power lens element.
2. Background of the Art
Manufacturers have encountered and overcome numerous technical challenges presented by chemical compounds that are newly incorporated into optical elements, such as ophthalmic lenses. First, there were new formulations for inorganic glasses. Those new glass formulations required development of new processing steps and conditions, as well as new grinding and polishing techniques. Later, industry focus shifted to thermoset resins and polymers, such as allyl diglycol carbonate, one brand of which is sold under the CR-39® trademark of PPG Industries, Inc. A more recent development involves manufacture of ophthalmic lenses using thermoplastic materials and polymers, such as polycarbonate polymers.
Polycarbonate is an amorphous, thermoplastic material that has mechanical properties that are very desirable for ophthalmic lenses. For example, ophthalmic lenses made of polycarbonate have unusually high impact resistance and strength which make the lenses surprisingly shatter-resistant. Also, the relatively low specific gravity of polycarbonate makes it possible to significantly decrease the weight of polycarbonate lenses, as compared to glass or CR-39® lenses. Polycarbonate is highly transparent and has a desirably high refractive index for ophthalmic lens applications. Furthermore, the good thermal properties of molten polycarbonate makes the material conducive to efficient processing by conventional techniques, such as injection molding.
Despite the advantages of the material, incorporation of polycarbonate into ophthalmic lens manufacture has not been without problems. For example, the hardness of the material necessitated development of grinding and polishing techniques different from techniques used for glass and CR-39® lenses. Additional challenges remain that have not been satisfactorily addressed to date. Some of these challenges relate to incorporation of functional properties into lenses made of polycarbonate. Functional properties include features, such a) as light or other radiation filtering, and b) cosmetic and durability features, which may be incorporated into an optical lens to impart or modify lens characteristics, other than optical power or magnification characteristics. Some examples of functional properties include light polarization, photochromism, tint, color, decor, indicia, hardness, and abrasion resistance.
There are various examples of shortcomings relating to polycarbonate ophthalmic lenses and to techniques for manufacturing polycarbonate ophthalmic lenses. For example, no method presently exists for making polarized polycarbonate lenses capable of meeting ophthalmic prescription specifications—that is, creating polarized polycarbonate lenses with different focal powers. Also, no method presently exists for quickly and efficiently making high quality photochromic polycarbonate lenses. Furthermore, no method is available for efficiently and effectively incorporating functional properties into ophthalmic lenses made of new materials or materials that have not yet been adapted to ophthalmic lens manufacture.
Numerous methods for incorporating polarizing properties into lenses made of material other than thermoplastic material are known. For example, U.S. Pat. No. 3,051,054 to Crandon describes a method of providing a glass lens with a film of light-polarizing material. Also, U.S. Pat. No. 4,495,015 to Petcen describes a method of laminating a thermoset/thermoplastic wafer to an ophthalmic glass lens.
Various patents disclose methods of incorporating a polarizing film or wafer within a lens cast of thermoset material. For example, U.S. Pat. No. 3,786,119 to Ortlieb discloses a laminated plate of polarizing plastic material that is formed into a polarizing screen. The polarizing screen is placed within a mold which is filled with polymerizable or polycondensible liquid resin. U.S. Pat. No. 3,846,013 discloses a light-polarizing element formed by sandwiching light-polarizing material between thin layers of optical quality transparent polymeric material. The light-polarizing element is placed within a mold, and a polymerizable monomer is placed in the mold on either side of the light-polarizing element.
U.S. Pat. No. 3,940,304 to Schuler discloses a shaped light-polarizing synthetic plastic member that is disposed between layers of an optical quality synthetic monomeric material in a mold. A monomeric material is placed within the mold and polymerized to form a composite synthetic plastic light-polarizing lens structure. U.S. Pat. No. 4,873,029 to Blum discloses a plastic wafer that may include polarizing features. The plastic wafer is inserted into a mold between liquid monomer molding material. The mold is then subjected to oven-curing to polymerize the liquid monomer. Additionally, U.S. Pat. No. 5,286,419 to van Ligten et al. discloses a shaped polarizing film that is embedded in pre-gelled resin. The resin is cured to form a light polarizing lens.
However, despite the availability of these methods for incorporating a polarizing film or wafer within a lens cast of thermoset material, a need remains for an improved polarizing lens. For example, delamination of cast polarizing lenses remains a significant problem. Also, cast lenses are relatively heavy and offer less than adequate levels of impact and shatter resistance. Finally, manufactures continue to encounter difficulties making polarizing cast lenses with optimum refractive index values.
Another reference, U.S. Pat. No. 5,051,309 to Kawaki et al., concerns a polarizing plate that is made by laminating polycarbonate film on both sides of a polarizing thin layer. The polarizing thin layer is composed of a polymeric film and a dichroic dye oriented on the polymeric film. According to the patent, suitable uses of the polarizing plate include goggles and sunglasses. However, the polarizing plate of U.S. Pat. No. 5,051,309 would not be suitable for use as an optical lens capable of meeting ophthalmic prescription specifications. For example, the polycarbonate film included in the polarizing plate of this patent lacks the material integrity needed for successful grinding and polishing of polycarbonate optical elements to prescription specifications. Polycarbonate that is ground and polished to make optical elements must have sufficient material integrity to withstand the heat and pressure generated during grinding and polishing operations. The lack of material integrity of the polycarbonate film used in the Kawaki polarizing plate would affect cosmetic properties, as well as, the impact strength of any prescription specification optical elements made by grinding and polishing the polycarbonate film.
As noted, another challenge concerns incorporation of photochromic properties into polycarbonate lenses. For example, present polycarbonate lenses that include photochromic material offer marginal, and even unacceptable, photochromic properties and cosmetic qualities. Indeed, no method presently exists for making high quality photochromic polycarbonate lenses.
Two current methods of incorporating organic photochromic dyes into thermoplastic materials, such as polycarbonate, involve either inclusion of organic photochromic dye throughout the thermoplastic material or imbibition of photochromic dye into a surface of the thermoplastic material. Existing techniques, such as injection molding, for including organic photochromic dyes throughout thermoplastic materials, such as polycarbonate, typically do not yield satisfactory results. It is believed that the unsatisfactory results occur for several reasons, including the relatively high temperatures required for satisfactory injecti
Bhalakia Sujal
Moravec Thomas J.
Epps Georgia
Litman Mark A.
Mark A. Litman & Assoc.
Schwartz Jordan M.
Vision--Ease Lens, Inc.
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