Abstract:
A mirrored lens of a plano or ophthalmic type using hardcoats and a topcoat to provide a more durable and easily cleaned.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     The present invention relates to a piano or ophthalmic sunglass lens with a mirror coating thereon.  
         [0003]     2. Background Information  
         [0004]     For decades and decades, individuals have worn sunglasses to reduce the amount of sunlight to the eyes when outdoors. One particular type of sunglasses that has grown in popularity is a mirrored lens. However mirrored sunglasses have several disadvantages including lack of durability and lack of ease of cleaning.  
       SUMMARY OF THE INVENTION  
       [0005]     The inventor has discovered an improved mirrored sunglass lens, and a method of manufacturing. The invention provides a more durable and easier cleaned mirror lens for use as a piano or ophthalmic sunglass lens or other mirrored surface.  
         [0006]     The invention is a mirrored lens having a substrate with a hardcoat primer layer, at least one hardcoat layer, a mirror layer and a hydrophobic topcoat. The process of making the invention of a mirrored lens involves etching a substrate, applying a hardcoat primer, curing the hardcoat primer, applying a hardcoat, curing the hardcoat, applying a mirror layer, and applying a hydrophobic topcoat. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     Preferred embodiments of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.  
         [0008]      FIG. 1  is a cross sectional view of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0009]     The improved mirrored lens of the present invention is generally shown in  FIG. 1 , which is more durable and easily cleaned. One application is mirrored sunglasses.  
         [0010]     The invention in one embodiment is a mirrored lens which is an uncoated substrate or lens body  10  with a multiple stage hardcoat such as a first hardcoat  22  and a second hardcoat  24  that is harder but typically more brittle than the first hardcoat, a mirror surface  26 , and a hydrophobic topcoat  28 . In another embodiment, the invention is a lens  10  with a hardcoat primer  20 , a multiple stage hardcoat such as a first hardcoat  22  and a second hardcoat  24  that is harder but typically more brittle than the first hardcoat, a mirror surface  26 , and a hydrophobic topcoat  28 . In yet another embodiment, the invention is a lens  10  with a hardcoat primer  20 , a single stage hardcoat hardcoat  22 , a mirror surface  26 , and a hydrophobic topcoat  28 . In yet a further embodiment, the invention is a lens  10  with a mirror surface  26 , and a hydrophobic topcoat  28 . In other embodiments, the topcoat is of other materials that have similar slippery characteristics to avoid scratches by reducing friction.  
         [0011]     In one embodiment, the process of manufacturing a mirrored lens is as follows. The substrate or uncoated lens  10  should preferably be cleaned such as with solvent, detergent or ultrasonic processes for example followed by a rinse such as with water and/or de-ionized water. The lens  10  is then etched such as by a chemical etch which in one process is any caustic etching agent such a potassium hydroxide. A mechanical etch is also an available manner to etch, and plasma or other etching techniques may also be used. An optional hardcoat primer  20  is then applied to lens  10  typically via a dipping process although other methods may be used, cured (thermally or by ultraviolet radiation or other methods). The next step is a dipped hardcoat that is cured such as thermally. The lens  10  is then optionally ion etched in a vacuum chamber such as one used for mirror deposition such as by ion etching where argon ions are bombarded against the lens. A hardcoat of a harder but more brittle material is then evaporated on such as via physical vapor deposition (PVD). Thereafter, a mirror is applied either in the form of a mirror metal only, or as a metal with multiple dielectric layers over metal, or all dielectric layers. Optionally, glue layers, environmental barrier layers and ion guns may be used. Finally, a hydrophobic topcoat is added.  
         [0012]     In a preferred embodiment, the process of manufacturing a mirrored lens  10  is as follows. The lens  10  is cleaned with detergent, ultrasonic and de-ionized water. The lens  10  is then etched such as by a chemical etch or other techniques which in one process is any caustic etching agent such a potassium hydroxide. A hardcoat primer  20  is then applied to lens  10  and cured. Thereafter, a thermal cure hardcoat  22  is applied and cured. The lens is then ion etched in a vacuum chamber used for mirror deposition. Another hardcoat such as of SiO 2  may additionally then be evaporated thereon with an electron beam gun (or other methods) and also with or without ion gun assisted deposition. Thereafter, a mirror is applied either in the form of a mirror metal only, or as a metal with multiple dielectric layers over metal, or all dielectric layers. Optionally, glue layers, environmental barrier layers and ion guns may be used. Finally, a hydrophobic topcoat is added.  
         [0013]     The invention is unique, novel, and nonobvious by adding successive harder layers via primers and hardcoats to a lens that will be mirrored in order to create a more rigid structure to support the mirror while absorbing the thermal stresses when forces are placed thereon. The invention requires more aggressive etching steps than typical coating processes such as are used in typical anti-reflective coatings or known mirrors. These would involve longer etching, higher temperature etching, and more concentrated chemicals, which are needed to apply and assure adherence of the hardcoats. The hardcoats need additional roughness to adhere to the lens whereby known mirrors do not require this steps, and known anti-reflective coatings may use light etching only as aggressive etching will result in scratches that remain in the lens. The hardcoat successfully fills scratching and surface roughness caused by the aggressive etching while also resulting in a better bond due to the aggressive etching. The hardcoat is typically 5 to 7 microns thick which provides for a stiffer layer than known techniques.  
         [0014]     The invention is further unique, novel and nonobvious by providing a slippery surface to the mirror such as a hydrophobic to reduce scratching. It was further discovered that this invention of a hydrophobic topcoat may be applied over most raw or plain lenses, or lenses with existing or known hardcoats such as polarized polycarbonate lenses.  
         [0015]     This combination of hardcoats and topcoat is approximately four times more durable and scratch resistant than a typical mirror under an eraser and steel wool scratch test. The process also provides for better adhesion than known processes as determined by accelerated weather tests.  
         [0016]     Accordingly, the invention as described above and understood by one of skill in the art is simplified, provides an effective, safe, inexpensive, and efficient device, system and process which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior devices, systems and processes, and solves problems and obtains new results in the art.  
         [0017]     In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0018]     Moreover, the invention&#39;s description and illustration is by way of example, and the invention&#39;s scope is not limited to the exact details shown or described.  
         [0019]     Having now described the features, discoveries and principles of the invention, the manner in which it is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims.