Optical: systems and elements – Lens
Reexamination Certificate
1999-01-11
2001-07-03
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
C359S493010, C359S359000, C351S177000, C351S172000
Reexamination Certificate
active
06256152
ABSTRACT:
The present invention relates to the manufacture of plastic optical articles such as sunglass lenses, ophthalmic lenses and the like. In particular, the present invention relates to the manufacture of laminate optical articles.
It is known in the prior art that in the manufacture of optical articles it is often desirable to provide additional properties to the articles, for example polarisation, UV inhibition, photochromism, electrochromism, or colouration of lenses.
Such properties are normally provided by the addition of a coating or surface treatment to the finished lens. However, such treatments are difficult and expensive to apply, and may be removed from the optical surface by scratching, wearing or the like.
Further, for example, it is known in the prior art to incorporate photochromic dyes into a plastic lens via surface imbibation techniques. See for example U.S. Pat. No. 5,130,353, or U.S. Pat. No. 5,185,390, which describe the inclusion of photochromic dyes into the subsurface region of a plastic lens by first positioning a polymeric or other carrier or photochromic dye physically against the surface of the lens and then using heat to cause the dyes to diffuse into the lens. Such techniques are both difficult and expensive, and require careful control of the depth of absorption in order to achieve a constant colour for the lens.
Further, it has been proposed in the prior art, e.g. in Japanese Patent 1259591 (1984) and Japanese Patent application 5181016 (1993), to introduce a film having desirable properties by placing a foil into a mould and cast polymerising a lens. Numerous problems have been associated with this art, however, including the formation of bubbles, haze and visible stress birefringence in the finished lens.
It would therefore be a significant advance in the art to provide a process for improving optical properties which was easy to handle and produced a product of enhanced durability.
It is accordingly an object of the present invention to overcome, or at least alleviate, one or more of the difficulties or deficiencies related to the prior art.
Accordingly, in a first aspect of the present invention there is provided a laminate optical article including
a first outer layer;
a second outer layer; and
an inner layer positioned between said first and second outer layers, the inner layer providing a desirable optical property to the laminate optical article.
The laminate optical article may be characterised by improved durability and ease of handling. The laminate structure provides a product the components of which are of relatively simple geometry and are thus easy to manufacture.
The first outer layer may form a front or back wafer of a laminate optical lens. The first outer layer may include an optical surface and an interface or mating surface. The optical surface may have different optical powers along different meridians. Alternatively the optical surface may include an aspheric bi-focal, tri-focal or progressive multi-focal region or regions.
The first outer layer may be formed from any suitable material. A mineral glass or optical polymeric material may be used. The polymeric material may be of any suitable type. The polymeric material may include a thermoplastic or thermoset material. A material of the polycarbonate type, may be used. The laminate optical article is particularly suitable in polycarbonate applications. The laminate optical article may reduce or eliminate difficulties associated with the high stress co-efficient of birefringence associated with polycarbonates. The consequence of this is that when polycarbonate is moulded utilising conventional processes, flow lines and areas of stress are highly visible, for example when viewed through a polarising film.
Alternatively, the polymeric material may be of the diallyl glycol carbonate type, for example the product sold under the trade designation CR-39 (CR-39 is a Registered Trade Mark of PPG Industries, Inc.).
The polymeric material may be formed from cross-linkable polymeric casting compositions, for example as described in applicants U.S. Pat. No. 4,912,155, U.S. patent application Ser. No. 07/781,392, Australian Patent Applications 50581/93 and 50582/93, and European Patent Specification 453159A2, the entire disclosures of which are incorporated herein by reference.
Such cross-linkable polymeric casting compositions may include a diacrylate or dimethacrylate monomer (such as polyoxyalkylene glycol diacrylate or dimethacrylate or a bisphenol fluorene diacrylate or dimethacrylate) and a polymerisable comonomer, e.g. methacrylates, acrylates, vinyls, vinyl ethers, allyls, aromatic olefins, ethers, polythiols and the like.
For example, in Australian Patent Application 81216/87, the entire disclosure of which is incorporated herein by reference, applicant describes a cross-linkable coating composition including at least polyoxyalkylene glycol diacrylate or dimethacrylate and at least one poly functional unsaturated cross-linking agent.
Further, in Australian Patent Application 75160/91, the entire disclosure of which is incorporated herein by reference, applicant describes a polyoxyalkylene glycol diacrylate or dimethacrylate; a monomer including a recurring unit derived from at least one radical-polymerisabie bisphenol monomer capable of forming a homopolymer having a high refractive index of more than 1.55; and a urethane monomer having 2 to 6 terminal groups selected from a group comprising acrylic and methacrylic groups.
Such polymeric formulations are UV cured or cured by a combination of UV and thermal treatment. The range of optical lenses sold under the trade designations “Spectralite” by Applicants have been found to be suitable.
The polymeric material may include a photochromic dye which may, for example, be added to the monomer formulation used to produce the polymeric material.
The second outer layer of the laminate optical article may be of any suitable type. The second outer layer may form a protective coating for the inner layer described above. The protective coating may include one or more of the groups consisting of an abrasion resistant component, a water resistant component and an antistatic component. A peel-off protective layer may be used. The protective coating may be formed of a polymeric material. A vinyl polymer material may be used. A vinyl chloride/vinyl acetate copolymer is preferred. The protective coating may further include conventional components including plasticisers, anti-static agents and the like.
The laminate optical article so formed may be packaged for later lamination to, for example, a front or back lens wafer. A water-barrier resistant package may be used, Such packages may control relative humidity such that the stability of curvature of the lens wafers is retained. A package of the type described in U.S. Pat. No. 5,323,192 to applicants, the entire disclosure of which is incorporated herein by reference, may be used.
Alternatively, the second outer layer may form a complementary back or front wafer of a laminate optical lens. The second optical layer may form a complementary back or front wafer to the first outer layer. The second outer layer may be formed in a complementary though reverse manner to the first outer layer.
Accordingly, in a preferred aspect of the present invention there is provided a laminate optical article including
a front lens wafer formed from a optical polymeric material;
a second complementary back lens wafer formed from a optical polymeric material; and
an inner layer positioned between said front and back wafer and having a shape complementary to a surface complementary to a surface of the front and/or back wafer, the inner layer providing a desirable optical property to the laminate optical article.
If desired, there may be a distribution of distance power and cylinder between the front and back lens wafers. Alternatively, the back lens wafer may be relatively thick, the laminate optical article forming a semi-finished lens.
The inner layer may be of any suitable type. The inner layer may include a polymeric fi
Coates Paul John
Coldrey Peter Wallace
Cuthbertson Matthew John
Kloubek Helena
Burns Doane Swecker & Mathis L.L.P.
Epps Georgia
Lucas Michael A.
Sola International Holdings Ltd.
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