Electric heating – Metal heating – By arc
Reexamination Certificate
2000-03-13
2001-08-28
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
By arc
C351S159000
Reexamination Certificate
active
06281468
ABSTRACT:
The present invention relates to the marking of ophthalmic lenses and in particular spectacle lenses, for the purpose of identifying the manufacturer, origin or characteristics of the lens. Such marking is commonly referred to as “monogramming”.
BACKGROUND OF THE INVENTION
There are a wide variety of methods of marking ophthalmic lenses. Some involve the selective removal of the ophthalmic lens material and/or coatings thereon, namely by mechanical engraving and etching and by means of lasers and excimers. Such markings are generally visible to the naked eye with or without special lighting conditions and may be colored with pigments for enhanced visibility. Eyeglass wearers have objected to such permanent markings which can be seen when the eyeglasses are worn. The same holds for colored transfer and photochromic markings in or on the body of the lens material.
Other kinds of markings are normally invisible but can been rendered visible by fogging the lens, in practice, simply by exhaling against the lens to produce a thin layer of condensation. Essentially such methods involve the change in the surface characteristics of the lenses. Some known coatings have high surface energies such as anti-reflective coatings. Others, such as top coats used as anti-smudge coatings to avoid dust and grime collecting on the lens have low surface energies. Typically the high or low surface energy material is selectively chemically modified or even removed to the configuration of the indicia desired. Fogging reveals the low surface energy parts as light colored droplets and the high surface energy parts as darker colored condensate film.
Danielos et al. U.S. Pat. No. 4,912,298 discloses a method of producing a marking on a spectacle lens by irradiation of defined regions of the spectacle lens with a high energy excimer laser through a suitably cutout metal mask spaced from or on the lens which vaporizes a thin layer (0.1 &mgr;m ) of a lens so that the marking is recognizable as a breath mark.
In European patent application No. 0 031 633 indicia are provided on a lens surface of a polycarbonate lens by applying concentrated sulfuric acid by means of a printing block, pencil or brush to increase the surface energy of the marked portion and visible when fogged with one's breath. Such a method does not admit of precise delineation of the marked portion and also requires careful washing and drying.
French patent application publication No. 2,727,649 discloses a method of marking eyeglass lenses of organic material with or without antiscratch coating or metallic reflective coatings. This method involves subjecting the face of the lens to be marked to a corona discharge, a flame or ionized air in order to increase the surface energy and thereby improve adherence of the surface to be marked. The actual marking is produced by pad transfer or silk screening printing with a special marking ink comprising an ink and an anti-fogging agent, which is then dried and thereafter the ink component is removed with an appropriate solvent.
European patent No. 0.472.303 concerns a hydrophobic contact lens casting mold, e.g. of polyolefin, which is subject to a hydrophilizing treatment, namely by means of an electrical corona discharge to enhance the adhesion of a hydrophilic monomer coloring dispersion without interference with the release properties of the mold.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is to provide a simplified method and apparatus for providing a high surface energy marking of an ophthalmic lens surface having a low surface energy which is rendered visible by fogging.
According to one aspect of the invention, there is provided an apparatus and related method for producing a relatively high surface energy marking on a surface of an ophthalmic lens having low surface energy. The apparatus comprises a surface energizing source, means for applying a mask on a surface of an ophthalmic lens to be marked, the mask defining a reverse image of a desired marking, means for positioning the surface of the lens to be marked facing the surface energizing source with the mask interposed between the surface energizing source and the surface of the lens to be marked, the energizing discharge of the energizing source increasing the surface energy of the surface to be marked so as to render the resulting marking visible by fogging.
According to one preferred embodiment of the invention, the mask is a part of a flexible screen which is impermeable to the surface energizing discharge and has a cutout corresponding to the reverse image of the desired marking. The mask part of the screen mates with the lens surface to be marked when the lens is pressed against the screen held taut. With such an embodiment, the selective modification of the surface energy is effectively a single step treatment of the lens, eliminating one or more steps heretofore necessary, before and/or after.
According to another preferred embodiment, an ink mask is stamped directly on the surface of the lens. The mask is impermeable to the surface energizing discharge. The ink mask on the lens is brought in position facing the surface energizing source. After treatment, the ink mask on the lens is removed, e.g. with a suitable solvent. The application of an ink mask permits a very sharp and precise marking and also a virtually infinite variety of markings since it is not dependent on the mechanical characteristics of a cutout screen mask. Moreover, an ink mask permits the concave as well as the convex surfaces of the lens to be marked.
The energizing source described above is a corona discharge source. Although a corona discharge source is preferred, other energizing sources may be used, namely ultraviolet radiation sources or glow discharge sources and low temperature plasma sources.
These and other features of the present invention will be brought out in the description which follows, by way of example with reference to the accompanying drawings.
REFERENCES:
patent: 3657085 (1972-04-01), Hoffmeister et al.
patent: 3879183 (1975-04-01), Carlson
patent: 4145125 (1979-03-01), Chika
patent: 4898459 (1990-02-01), Eriksson
patent: 4912298 (1990-03-01), Daniels et al.
patent: 5484467 (1996-01-01), Nass et al.
de Rojas Edward
Souel Thierry
Essilor International (Compagnie Generale d'Optique)
Evans Geoffrey S.
Young & Thompson
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