Plastic and nonmetallic article shaping or treating: processes – Optical article shaping or treating – Light polarizing article or holographic article
Reexamination Certificate
2000-06-09
2002-12-10
Vargot, Mathieu D. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Optical article shaping or treating
Light polarizing article or holographic article
C264S001700, C264S001800, C264S001360, C264S002500
Reexamination Certificate
active
06491851
ABSTRACT:
The present invention relates generally to a process for obtaining an ophthalmic lens comprising a surface utility microstructure and more particularly an antiglare microstructure.
Nowadays the most currently used means to impart antiglare properties to ophthalmic lenses, in particular in organic glass, is to coat on the lens a layer or a system of antiglare layers formed with mineral materials. The use of such antiglare layer in mineral materials has drawbacks in that it may modify the mechanical properties of the lens being obtained, and may modify more particularly the anti-abrasive properties of the hard anti-abrasive layers also coated on the ophthalmic lens.
Reaching optical properties from surface microstructures is a known art in optics. Thus, U.S. Pat. No. 5,630,902 discloses the transfer of a microstructure made with diffractive optical elements into a photopolymerizable material layer coated on a plastics substrate through die stamping, for example with the help of a quartz die supporting the desired microstructure.
U.S. Pat. No. 4,013,465 describes a process for producing a surface having a reduced reflection for electromagnetic radiation, having steps consisting in coating on a substrate surface a layer of a photosensitive material, exposing said material to a regular electromagnetic radiation pattern to which it is sensible and developing the sensible material so that the topography of the developed material surface corresponds to the light patterns so as to obtain a surface having a reduced reflection of the visible radiation.
GB-A-2,027,441 describes a process for producing an article comprising a monolithic plastics shaped layer or body consisting in some cross-linked polymers and comprising one or more surfaces bearing a microstructure replica, comprising the steps of filling a master mould bearing the microstructure with an oligomeric, cross-linkable, flowable fluidic composition being addition polymerizable with a radiation and having “hard” and “soft” segments, and of exposing the cast composition to an actinic radiation so as to form the item. Said document discloses that the term microstructure encompasses discontinuities, such as projections and indentations, in the surface, the profile of which varies from a median or central line passing through the microstructure so that the sum of the surfaces being circumscribed by the surface profile above the line equals the sum of the surfaces below the line, said line being essentially parallel to the normal surface (bearing the microstructure) of the item. The height of such deviations varies from ±0.05 &mgr;m to ±750 &mgr;m over a characteristic length representative of the surface, for example 1 to 30 cm. The medium profile or central line may be plane, concave, convex, aspherical or a combination of such shapes.
The items wherein such deviations are of a lower order, i.e. from ±0.005 &mgr;m to 0.1 &mgr;m or preferably ±0.05 &mgr;m and such deviations are infrequent or appear minimally, i.e. the surface is free from any significant discontinuity, are those for which the microstructure-bearing surface is a “flat” or “perfectly smooth” surface. Such items are useful for example as precision optical elements or elements with a precision optical interface, including ophthalmic lenses. The items for which such deviations are of a lower order but appear frequently are those for example bearing utility discontinuities, like in the case of items having an antiglare microstructure. Items for which deviations are of a high order, i.e. from ±0.1 &mgr;m to ±750 &mgr;m, to which a microstructure can be affected, comprising a set of utility discontinuities, that are identical or different, spaced apart or contiguous, randomly or orderly, are items such as back-reflective sheets, linear Fresnel lenses and video discs. Moreover, said document mentions that it can be necessary or desired to choose particular oligomeric compositions the hardening shrinkage of which is weak so as to avoid parasitic discontinuity occurrence interfering with the utility discontinuities.
The present invention has thus as an object a process for obtaining an ophthalmic lens, i.e. an item having a sight-correcting geometry, comprising a surface utility microstructure, i.e. having optical properties, in particular antiglare properties, the utility microstructure geometry being initially determined by an interferential process.
The present invention has also as an object said thus obtained lenses comprising a sight-correcting geometry surface provided with a utility microstructure, in particular having antiglare properties, the geometry of which is initially determined through an interferential process.
An object of the present invention is thus to provide a process for obtaining an ophthalmic lens, i.e. an item having a sight-correcting geometry comprising a surface utility microstructure, i.e. optical properties, in particular antiglare properties, the utility microstructure geometry being initially determined by an interferential process.
Another object of the present invention is also the so-obtained lenses comprising a sight-correcting geometry surface provided with a utility microstructure, in particular antiglare properties, the geometry of which is initially determined by an interferential process.
Such a utility microstructure may be realised in a surface of the lens itself or in a surface functional layer of the ophthalmic lens.
According to the invention, the process for obtaining an ophthalmic lens comprising a surface utility microstructure the geometry has been initially determined through an interferential process, comprises a step for transferring the microstructure from a mould an internal surface of which supports the microstructure and has a sight-correcting geometry.
Preferably, the sight-correcting geometry surface is a progressive geometry surface. Generally, the bend of the mould progressive geometry surface has a bending radius being measured at any point of the correcting surface comprised between 40 mm and 100 mm.
According to the present invention all conventional moulding types may be used to manufacture ophthalmic lenses such as direct moulding, for example through an integral mould or a composite mould, with added elements or with insert, or overmoulding, and the so-called “transfer” mouldings, for example by die-stamping, or with the well-known method in ophthalmic optics with “In-Mold Coating” transfer.
In a first embodiment of the invention, the mould being used is an integral mould, i.e. the utility microstructure is formed directly in an internal mould surface having the required sight-correcting geometry. The mould may be made with plastics, mineral glass or metal, particularly nickel.
In a second embodiment of the invention, the mould is a composite mould comprising an insert having a surface in which the utility microstructure is formed, said insert suiting to the mould surface having the sight-correcting geometry, so that the insert surface comprising the utility microstructure should also have the required sight-correcting geometry. The insert may be initially shaped so as to have the required sight-correcting geometry and be secured to the corresponding mould surface, for example with an adhesive. The insert may also have initially a plane shape and be then distorted to suit to the mould sight-correcting geometry surface. In this last case, the insert may also be secured to the mould sight-correcting geometry surface with an adhesive. When the microstructure-bearing insert is a plastic element adapted to be applied on a surface of a mould, said element must have a minimum elasticity is in the plane to be able to be correctly applied. Such convenient elements are polyurethane elements having for example a Young modulus measured at 30° C. of 1.2 Gigapascals. Generally, said convenient elements have a lower Young modulus than 2.5 Gigapascals.
Finally, the insert may be made with a layer of such a material as a plastics directly formed on a surface of a substrate.
In a th
Bosmans Richard
Braley Walter Charles
Dufresne Jean-François
Keller Gerhard
Massey Gilles
Essilor International (Compagnie Generale d'Optique)
Fulbright & Jaworski L.L.
Vargot Mathieu D.
LandOfFree
Method for obtaining an ophthalmic lens comprising a surface... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for obtaining an ophthalmic lens comprising a surface..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for obtaining an ophthalmic lens comprising a surface... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2927802