Abstract:
An optical device for providing prescription correction to a mirror so that a person who normally wears prescription glasses may clearly see, and also have unobstructed access to, their face in order to apply makeup. A magnifying lens in the form of an eyeglass blank of an appropriate corrective power is removably attached to the mirror by means of a suction cup and a hook element. The magnifying lens has a hole joining its two refracting surfaces. One end of the hook element fits through the hole and the other end of the hook element is attached to the suction cup. The lens situated in close proximity to the mirror provides a user who normally wears prescription eyeglasses with the appropriate corrective power to enable them to clearly see their face while providing good working room for them to perform tasks such as applying their makeup.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to, and claims priority from, U.S. Provisional Patent application No. 60/745,576 filed on Apr. 25, 2006 by Candace Rymniak entitled “Optical Apparatus for Providing Prescription Correction to a Mirror”, the contents of which are hereby incorporated by reference. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to optical devices, and more particularly to optical devices for providing prescription correction to mirrors to provide vision corrected, focused images at distances suitable for tasks such as applying cosmetics. 
       BACKGROUND OF THE INVENTION 
       [0003]    People who wear prescription glasses have difficulty using mirrors for tasks such as applying cosmetics. Their face, particularly their eyes, is obstructed if they are wearing their glasses. Without their glasses, however, they cannot see their face clearly. 
         [0004]    Many people have attempted to address this issue. A fairly recent summary of these attempts over the years is provided in, for instance, the background section of U.S. Pat. No. 6,441,696 issued to Goldstein et al. on Aug. 27, 2002 entitled “Prescription Mirror”, the entire contents of which are hereby incorporated by reference. 
         [0005]    An early summery is provided in, for instance, U.S. Pat. No. 3,970,369 issued to Wachsman on Jul. 20, 1976 entitled “Corrective makeup and employing prescription lenses”, the contents of which are hereby incorporated by reference. 
         [0006]    Despite the many attempts to address this issue, a simple, portable apparatus that can be used on existing mirrors to allow a person who normally wears prescription glasses to both see and have unobstructed access to their face, particularly their eyes, is still needed. 
       SUMMARY OF THE INVENTION 
       [0007]    Briefly described, the invention provides a lens and a means for removeably attaching the lens to a mirror so as to enable a person who normally wears prescription glasses to both see and have unobstructed access to their face, and more particularly to their eyes, for the purpose of tasks such as, but not limited to, applying makeup. 
         [0008]    In a preferred embodiment of the invention, a lens in the form of an eyeglass blank of an appropriate corrective power is removably attached to a mirror by means of a suction cup and a hook element. For use, the suction cup may be fixed to the mirror and the lens may, for instance, hang from the suction cup by means of the hook element. 
         [0009]    The lens situated in close proximity to the mirror provides a user who normally wears prescription eyeglasses with the appropriate corrective power to enable them to clearly see their face while providing enough working room for them to perform tasks such as, but not limited to, applying their makeup. The lens arrangement of the present invention may be used on magnifying mirrors but it is also effective even if the mirror to which the lens is attached is a flat, non-magnifying mirror. 
         [0010]    These and other features of the invention will be more fully understood by references to the following drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a three dimensional, schematic drawing of a preferred embodiment of the invention. 
           [0012]      FIG. 2  is a cross-sectional drawing of a preferred embodiment of the invention attached to a concave mirror. 
           [0013]      FIG. 3  is a cross-sectional drawing of a preferred embodiment of the invention attached to a flat mirror. 
           [0014]      FIG. 4  is a cross-sectional drawing of a further preferred embodiment of the invention including a laterally pivoting extension arm. 
           [0015]      FIG. 5  is a cross-sectional drawing of a further preferred embodiment of the invention including a concertino extension arm. 
           [0016]      FIG. 6A  is a schematic representation of a viewer looking at their own lips using a corrective lens and a mirror. 
           [0017]      FIG. 6B  is a schematic representation of a viewer looking at an object at an equivalent distance as their lips where in  FIG. 6A  using a corrective lens where the mirror in  FIG. 6A  was. 
           [0018]      FIG. 6C  is a schematic representation of a viewer looking at their own lips using a corrective lens placed in close proximity to a mirror. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The present invention applies to a simple, portable optical device for providing prescription correction to a mirror to provide vision corrected, focused images at suitable distances for such tasks as applying cosmetics. 
         [0020]    An objective of the present invention is to provide a low cost, easy to use, portable device to enable people who normally wear prescription glasses a way to use a mirror while performing tasks such as, but not limited to, putting on their makeup. 
         [0021]    A preferred embodiment of the invention will now be described in detail by reference to the accompanying drawings in which, as far as possible, like elements are designated by like numbers. 
         [0022]    Although every reasonable attempt is made in the accompanying drawings to represent the various elements of the embodiments in relative scale, it is not always possible to do so with the limitations of two-dimensional paper. Accordingly, in order to properly represent the relationships of various features among each other in the depicted embodiments and to properly demonstrate the invention in a reasonably simplified fashion, it is necessary at times to deviate from absolute scale in the attached drawings. However, one of ordinary skill in the art would fully appreciate and acknowledge any such scale deviations as not limiting the enablement of the disclosed embodiments. 
         [0023]      FIG. 1  is a three dimensional drawing of a preferred embodiment of a correction providing optical device  10 . The correction providing optical device  10  includes an eyeglass optical lens blank  12 , a suction cup  18  and a hook  16 . The eyeglass optical lens blank  12  has a hole  14  machined in it that connects its two refracting surfaces. In use, the suction cup  18  is attached to a cosmetics mirror  20 . The eyeglass optical lens blank  12  is suspended from the suction cup  18  by the hook element  16  that is fitted through the hole  14  that connects the two refracting surfaces of the lens. A user  24  who normally wears prescription glasses may use the cosmetics mirror  20  in combination with the correction providing optical device  10  to see their own face, particularly their eyes, clearly enough, and with enough working room, to perform tasks such as, but not limited to, applying makeup. 
         [0024]    The eyeglass optical lens blank  12  may be a standard prescription eyeglass lens blank, without any additional edging but with a suitable hole  14  machined into it. The hole  14  connects the two refracting surfaces of the lens blank and is a suitable distance from the edge of the lens. Eyeglass lenses are typically curved meniscus lenses with the eye-side curve radius fixed at about 3.5 inches. Eyeglass lens blanks may be made of a variety of optical glass or plastic materials and are available in a variety of standardized sizes. For instance, Polycore Optical Pte. Ltd. of Singapore provides single vision finished lens blanks made from polycarbonate, hard resin and its propriety Index 1.56™ plastic in four diameters, 55 mm, 60 mm, 65 mm and 70 mm. Other manufactures also provide blanks with diameters of 75 mm and 80 mm. 
         [0025]    Eyeglass lens powers are typically measured in diopters. This measure is related to the focal length of the lens by the formula: 
         [0000]      Power in diopters=1000/focal length in mm. 
         [0026]    A lens with a power of 2 diopters, therefore, has a focal length of 500 mm. 
         [0027]    Lens blanks are typically available in 0.25 diopter increments. For instance, Polycore Optical Pte. Ltd. of Singapore provides its 55 mm and 60 mm diameter single vision finished blanks in powers from 0 diopters to +/−8.00 diopters in 0.25 Dioptor increments, and its 65 mm and 70 mm diameter single vision finished blanks in powers from 0 diopters to +/−6.00 diopters in 0.25 diopter increments. Polycore also provides 65 mm diameter, polycarbonate aspheric prescription lens blanks in 0.25 Diopeter increments from 0 to +/−6.00 diopters. 
         [0028]    The suction cup  18  may, for instance, be a clear plastic suction cup with hook such as, but not limited to, the range of suction cups supplied by Popco, Inc. of Minnetonka, MN. Popco&#39;s line of suction cups includes 1¾″ diameter cups made of medical grade PVC for superior suction capability. 
         [0029]      FIG. 2  is a cross-sectional drawing of a preferred embodiment of the invention attached to a concave mirror. Most cosmetics mirror  20  provide a degree of magnification. In this embodiment of the invention, the correction providing optical device  10  may augment the magnification provided by the cosmetics mirror  20  and provide any prescription correction required by the user  24 . 
         [0030]    In use, the suction cup  18  may be attached to a cosmetics mirror  20 . A hook element  16  that may be formed of metal, plastic or any other suitable material has one end threaded through the hole or aperture  14  that has been machined through the eyeglass optical lens blank  12 . The other end of the hook element  16  is attached to the suction cup  18  so that in combination they secure the eyeglass optical lens blank  12  against a reflecting surface of the cosmetics mirror  20 . In a preferred embodiment, the eyeglass optical lens blank  12  is positioned so that a concave surface of the lens confronts the reflecting surface of the cosmetics mirror  20 . 
         [0031]      FIG. 3  is a cross-sectional drawing of a preferred embodiment of the invention attached to a flat mirror  22 . In this embodiment, all the magnification is provided by the correction providing optical device  10 . 
         [0032]    Using an eyeglass optical lens blank  12  to provide the necessary magnification generally results in a better image quality than using a cosmetics mirror  20  alone to provide the same degree of magnification. The reason for this improvement in quality is the reduction in spherical aberration of the image. 
         [0033]    The cosmetics mirror  20  has only a single reflecting surface, while the eyeglass optical lens blank  12  of the correction providing optical device  10  has two refracting surfaces. In the eyeglass optical lens blank  12  the refraction of the imaging rays can, therefore, be divided equally between the two surfaces while the reflection of the imaging rays must be accomplished by a single surface in the cosmetics mirror  20 . For a given magnification, the eyeglass optical lens blank  12 , therefore, typically introduces significantly less spherical aberration than the cosmetics mirror  20 . Less spherical aberration results in a better image. Moreover, using an aspheric lens for the eyeglass optical lens blank  12  may reduce the spherical aberration even further. 
         [0034]    The cosmetics mirror  20  introduces no chromatic aberration, while the eyeglass optical lens blank  12  typically introduces a small amount of chromatic aberration that depends primarily on the optical properties of the material of which the eyeglass optical lens blank  12  is made. The human eye is, however, fairly tolerant of small amounts of chromatic aberration. 
         [0035]    Placing the eyeglass optical lens blank  12  in close proximity to the flat mirror  22  has an additional advantage of allowing a user  24  to use substantially the same lens prescription that they normally use for reading. The reason for this may be seen by reference to  FIGS. 6A ,  6 B and  6 C. 
         [0036]      FIG. 6A  is a schematic representation of a viewer looking at their own lips using a corrective lens and a mirror. The eye  38  is shown looking at an object  42  via a lens  40  and a mirror  44 . The user&#39;s eye  38  sees the object  42 , which may be their lips, as a magnified image  46 . The lens-to-object distance  48  is roughly twice the distance from the eye  38  to the mirror  44 . The lens-to-image distance  50  is related to the lens-to-object distance  48  and the power of the lens  40  by the laws of optics for thin lenses, that may be represented as the equation: 
         [0000]      1/lens-to-object distance+1/lens-to-image distance=1 /f    
         [0037]    Where f represents the focal length of the lens  40 . The focal length in mm equals 1000/power in diopters. 
         [0038]    The magnification=the lens-to-image distance/lens-to-object distance. 
       EXAMPLE A 
       [0039]    Lens power=2 diopters 
         [0040]    Lens-to-object distance=23 mm 
         [0041]    Lens-to-image distance=−42.5 mm 
         [0042]    Magnification=1.85 
         [0043]      FIG. 6B  is a schematic representation of a viewer looking at an object at an equivalent distance as their lips where in  FIG. 6A  using a corrective lens placed where the mirror in  FIG. 6A  was, but with the mirror removed. 
       EXAMPLE B 
       [0044]    Assuming the same power lens as in example A, 
         [0045]    Power of lens=2 diopters 
         [0046]    Lens-to-object distance=12.5. 
         [0047]    Lens-to-image distance becomes=16.5 mm 
         [0048]    Magnification=1.33 
         [0049]    Example B demonstrates that by moving the lens  40  approximately half-way to the object, the magnification of the image is significantly reduced, almost to half.  FIG. 6C , however, shows the actual optical arrangement that occurs in using the correction providing optical device  10 . When the lens is moved to being in close proximity to the mirror  44 , all imaging rays pass through the lens  52  twice. The lens  52 , therefore, effectively has twice the power of lens  40 . 
       EXAMPLE C 
       [0050]    Assuming the same lens as in example A, but having twice the optical power because of the imaging rays traversing it twice. 
         [0051]    Lens power=4 diopters 
         [0052]    Lens-to-object distance=12.5 mm 
         [0053]    Lens-to-image distance=25 mm 
         [0054]    Magnification=2 
         [0055]    So same lens placed next to the mirror is slightly more effective in magnification at that position when looking at objects on the face such as, but not limited to the lips, than when worn as eye glasses because of double transit of the imaging rays through the lens. This has the interesting advantage of allowing a user  24  to use an eyeglass optical lens blank  12  having the same prescription as the lens in their reading glass for the correction providing optical device  10 . 
         [0056]      FIG. 4  is a cross-sectional drawing of a further preferred embodiment of the invention including a laterally pivoting extension arm. The flat mirror  22  of the correction providing optical device  10  of this embodiment may be removably attached to a wall  23  by an attachment device  28  and a first arm  30  and a second arm  32 . The first arm  30  is attached to the second arm  32  by a pivot joint  34 . The pivot joint  34  allows the first arm  30  and the second arm  32  to pivot laterally with respect to each other, thereby allowing the correction providing optical device  10  to be positioned further from, or closer to, the wall  23 . The attachment device  28  may be a suction device, a magnetic device for metal walls, or other suitable device for removably attaching an object to a wall or to a mirror. In this embodiment, the suction cup  18  may be replaced by a permanent fastening device. 
         [0057]      FIG. 5  is a cross-sectional drawing of a further preferred embodiment of the invention including a concertino extension arm. The correction providing optical device  10  of this further embodiment is removably attached to the wall  23  by a concertino extension arm  36  and an attachment device  28 . In this embodiment, the suction cup  18  may be also replaced by a permanent fastening device. 
         [0058]    Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed invention. Modifications may readily be devised by those ordinarily skilled in the art without departing from the spirit or scope of the present invention.