Coating processes – Optical element produced – Transparent base
Reexamination Certificate
2000-09-06
2002-05-14
Beck, Shrive P. (Department: 1762)
Coating processes
Optical element produced
Transparent base
C427S169000, C427S430100, C118S423000, C118S425000, C118S428000, C118S500000, C414S331130, C414S331160, C414S331180, C414S800000
Reexamination Certificate
active
06387441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical articles such as ophthalmic lenses and, in particular, to a method and apparatus for hard coating the optical article to increase the abrasion resistance and enhance other physical properties of the optical article. The invention provides a continuous or semi-continuous method and apparatus for hard coating optical articles which is efficient and cost-effective wherein two carriages at a time are reciprocated separately on a conveyor in uncoated lens loading and coated lens unloading sections to provide from the loading section a carriage full of uncoated lens ready for hard coating and from the unloading section a carriage full of jigs for holding lenses which carriage is ready for transfer to the lens loading section.
2. Description of Related Art
Lenses are used for a wide variety of purposes such as microscopes and other optical instruments as well as ophthalmic lenses used for eye glasses. While the present invention involves a method and apparatus for hard coating any type optical articles or lenses, the following discussion will be directed for convenience of ophthalmic lenses.
Polymeric materials (e.g., plastics) have become the material of choice for ophthalmic lenses and have replaced the more traditional glass lenses for a number of reasons. Plastic is lighter than glass and there can be great reduction in the weight of the optical product. Plastics also may be provided in a wide range of fashionable colors and gradient-density tints and production techniques have improved so that plastic lenses can be manufactured at high rates and in a more automated fashion than glass lenses. Polymeric materials also offer great improvement over glass in terms of impact resistance and high refractive index. In general, plastic lenses are now the lenses of choice in the industry.
Plastic lenses may be manufactured in a variety of ways by individual casting techniques as well as injection molding processes. Regardless of the method of manufacture, however, the plastic lenses typically require a hard coating to increase the abrasion resistance of the plastic lens. The hard coating is typically applied by dipping the lens in a liquid hard coating solution and the coating is then cured by chemical cross-linking. U.S. Pat. No. 3,956,540 to Laliberte et al. entitled “Method of Coating Articles” is directed to a method and apparatus for applying a synthetic resin coating of predetermined thickness to ophthalmic lenses. Basically, the lenses are grouped and moved along a conveyor and are subjected to an ultrasonic cleaning. The cleaned lenses pass to a destaticizing station and then to a coating station where a dip tank is rapidly raised to immerse the lenses in the solution and the tank is then lowered at a controlled rate to provide a coating of the desired thickness on each lens in a single operation. The above patent is hereby incorporated by reference.
U.S. Pat. No. 5,750,060 to Maus et al. is directed to plastic injection-compression multi-cavity molding of flash-free improved-cleanliness thermoplastic spectacle lenses which are suitable to be robotically dip coated. A molded-on tab with each pair of lenses is specially suited for manipulation by a robot and the procedure produces micro-clean hard-coated paired molded lenses made entirely within a single continuous cleanroom air enclosure surrounding the lenses without any human operators therein. This patent is also incorporated herein by reference.
Regardless of the method used for making ophthalmic lenses and whether or not the lenses are single lenses or made together with tabs, there still exists a need for an automated cost-effective method for hard coating the lenses. The hard coating method and apparatus should be capable of being used with little or no human intervention and provide an efficient and reliable method for hard coating the lenses.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a batch, semi-continuous and/or continuous method for hard coating optical articles such as ophthalmic lenses which method is cost-effective and reliable and may be automated so that little or no human intervention is required.
It is another object of the present invention to provide an apparatus for batch, continuous and/or semi-continuous hard coating of optical articles such as ophthalmic lenses which apparatus is cost-effective and reliable and requires little or human intervention to operate the apparatus.
In another object of the invention hard coated optical articles such as opthalmic lenses made using the method and apparatus of the invention are also provided.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
SUMMARY OF THE INVENTION
This invention is directed in one aspect to a method and apparatus for hard coating ophthalmic lenses which is a sequential series of steps which steps may be employed together to form a completely automated and continuous method or which steps may be performed individually to provide a batch or semi-continuous method. Basically stated, a plurality of carriages for holding lenses are used which carriages move sequentially through the system. At one point in the method one or more of the carriages from an uncoated lens loading section contain uncoated lenses secured in jigs in the carriage. These carriages are then dip coated to form a coating on the jig secured lenses. Once coated, the carriage is moved to an unloading section in which the coated lenses are removed from the carriage and the carriage moved to the lens loading section. In the lens loading and unloading sections two carriages are used in sequence in a reciprocating motion as described hereinbelow.
In general, a plurality of carriages are moved through an uncoated lens loading section, a dip coating section, a coated lens unloading section and, then after the unloading section, the carriages are moved back to the uncoated lens loading section and the method repeated. The carriages may be moved through the system in any form such as on a conveyor and the carriage comprises a structure for holding a plurality of jigs in a front-to-back relationship and also preferably in a side-by-side relationship. Thus, a typical carriage will generally hold 6 jigs in a front-to-back relationship and 6 jigs in a side-by-side relationship. This provides a total of 36 jigs which may be held in each carriage. Each jig is capable of holding a single lens so that a total of 36 lenses may be held by jigs in each carriage. The carriages, while all the same structure, have different functions at different points in the method and apparatus and the carriages as they are used in the method an apparatus may be defined as follows:
1. A “filled jig carriage” means that the carriage is filled with jigs (without any lenses being secured in the jigs).
2. An “empty carriage” is a carriage which contains no jigs.
3. A “filled jig and uncoated lens carriage” means a carriage which contains uncoated lenses secured in jigs with the carriage being filled with jigs and secured uncoated lens to the desired carriage capacity.
4. A “filled jig and coated lens carriage” means a carriage which contains coated lenses secured in jigs with the carriage being filled with jigs and secured coated lens to the desired carriage capacity.
It is an important feature of the invention that the method and apparatus of the invention employ a leading empty carriage preceded by a filled jig carriage or a filled jig and coated lens carriage. In an uncoated lens loading section of the apparatus which employs an uncoated lens loading arm and an uncoated lens input conveyor or other lens loading device, a leading empty carriage is followed by a filled jig carriage. The filled jig carriage is moved adjacent the uncoated lens loading arm and the arm is manipulated to remove a single row of side-by-side jigs from the filled jig carriage. The filled jig car
Wu Yinghui
Yang Zhou
Beck Shrive P.
DeLio & Peterson LLC
Markham Wesley
Optima Inc.
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