Patent Document

This is a division of application Ser. No. 09/428,817, filed Oct. 28, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to tinted contact lenses and methods of making tinted contact lenses. 
     Tinted contact lenses are often used for cosmetic purposes to change the apparent color of the wearer&#39;s irises. For example, a person With brown or blue eyes but desiring to have green eyes may wear contact lenses having a greenish pattern thereon to mask the wearer&#39;s irises with the greenish pattern. 
     Conventionally, tinting of contact lenses is achieved by printing a colored pattern onto a lens substrate via a pad printing process. It is to be understood that the term “tinted” is intended to encompass colored patterns of translucent and/or opaque pigmentations. The pad printing process employs a generally flat steel plate also known as a cliché. A pattern (or depression) is etched into the cliché by a photo-etching process. In operation, ink placed in the pattern is transferred to the lens substrate by a printing pad. To achieve a tinted lens of multiple colors, different colored inks are placed into three or fewer different patterns and serially transferred to the lens substrate by printing pads. 
     A disadvantage associated with conventional methods of tinting contact lens substrates is that such methods cannot achieve patterns of high resolution. In other words, the printed pattern on the lens substrate does not have nearly the detail of a human iris. The inability to achieve patterns of high resolution also prevents use of more than three different patterns on a lens substrate. As such, an observer viewing the wearer&#39;s eyes from five feet away or closer may determine that the wearer is wearing tinted lenses. Another disadvantage is the extensive labor needed to etch a pattern into the cliché. Typically, four to six “man-hours” are required to etch each pattern. Moreover, the pattern must generally be etched to precise depths so that the ink can be transferred effectively. Etching to such precise depths is often difficult. In many intricate or detailed patterns, depth variances of 3-5 microns may render the cliché useless. Another disadvantage is that the corrosive chemicals (e.g., ferric chloride and hydrochloric acid) used to etch the pattern in the cliché are hazardous both to workers and to the environment. Thus, enhanced care and cost are needed in using and disposing of the chemicals. 
     SUMMARY OF THE INVENTION 
     Among the several objects and advantages of the present invention may be noted the provision of an improved method for tinting contact lens substrates; the provision of such a method of tinting a lens substrate in which the tinted lens substrate more closely resembles a human iris than does a tinted lens substrate made by conventional methods; the provision of a method of tinting a lens substrate to form a tinted lens having a pattern of greater intricacy; the provision of an improved method of forming a pattern in a cliché; the provision of a method of forming a precise, intricate pattern in a cliché; the provision of such a method of forming such a pattern in a less labor-intensive manner, the provision of a method of forming a pattern in a cliché without use of hazardous chemicals; and the provision of a tinted contact lens having a lens substrate a colorant image printed thereon of greater resolution than images printed on prior art tinted contact lenses. 
     In general, a method of the present invention for making a tinted contact lens for insertion into an eye comprises providing a plate having a surface, and lasing the plate to form at least one depression in the surface of the plate. The depression is of a shape constituting an iris portion pattern. A fluent colorant is introduced into the depression. The colorant is then transferred from the depression to a lens substrate in a manner so that the colorant colors the lens substrate in a colorant pattern of substantially the same shape as the iris portion pattern of the depression. 
     In another aspect of the present invention, a method of making a tinted contact lens for insertion into an eye comprises digitizing an image of a human iris into a computer. The digitized image is separated into a plurality of digitized image portions, which are used to form a plurality of depressions in a plurality of cliché portions. Each depression is of a shape constituting an iris portion patter. Fluent colorants are introduced into the plurality of depressions. The colorants are transferred from the depressions to the lens substrate in a manner so that the colorants color the lens substrate in a plurality of colorant patterns of substantially the same shape as the iris portion patterns of the depressions. The colorant patterns combine with one another to color the lens substrate in a manner to simulate a human iris. 
     In yet another aspect of the present invention, a tinted contact lens for insertion into an eye comprises a contact lens substrate and an iris-simulating pattern on the lens substrate. The iris simulating pattern comprises at least four distinctly colored colorants. 
     Other objects and features will be in part apparent and in part pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a tinted contact lens of the present invention having a contact lens substrate and an iris simulating design printed on the substrate; 
     FIG. 2 a  is fragmented top plan view of a printing plate (cliché) portion having a first depression therein, the first depression being in the shape of a first iris portion pattern to be printed onto a contact lens substrate to form a first portion of the iris simulating design of FIG. 1; 
     FIG. 2 b  is fragmented top plan view of a cliché portion having a second depression therein, the second depression being in the shape of a second iris portion pattern to be printed onto a contact lens substrate to form a second portion of the iris simulating design of FIG. 1; 
     FIG. 2 c  is fragmented top plan view of a cliché portion having a third depression therein, the third depression being in the shape of a third iris portion pattern to be printed onto a contact lens substrate to form a third portion of the iris simulating design of FIG. 1; 
     FIG. 2 d  is fragmented top plan view of a cliché portion having a fourth depression therein, the fourth depression being in the shape of a fourth iris portion pattern to be printed onto a contact lens substrate to form a fourth portion of the iris simulating design of FIG. 1; 
     FIG. 3 is a flow chart showing the steps in forming the patterns of FIGS. 2 a-d  in the cliché portions; 
     FIG. 4 a  is a schematic, side elevational view of the cliché portion of FIG. 2 a  showing ink filling the first depression and a doctor blade passed over the cliché portion to remove excess ink; 
     FIG. 4 b  is a schematic, side elevational view of the cliché portion of FIG. 4 a  in which a pad-printing pad is pressed against the cliché portion to transfer the ink from the depression to the pad; 
     FIG. 4 c  is a schematic, side elevational view of the pad of FIG. 4 b  aligned with a blank contact lens substrate; 
     FIG. 4 d  is a schematic, side elevational view similar to FIG. 4 c , but showing the pad pressed against the contact lens substrate to transfer ink from the pad to the lens substrate; and 
     FIG. 4 e  is a schematic, side elevational view similar to FIG. 4 d , but showing the pad removed from the lens substrate to reveal a pattern printed on the lens substrate. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and first more particularly to FIG. 1, a tinted contact lens of the present invention is indicated in its entirety by the reference numeral  20 . The contact lens  20  comprises a contact lens substrate  22  and an iris-simulating design, generally indicated at  24 , on the lens substrate. The contact lens substrate  22  is preferably a conventional clear contact lens. The lens substrate  22  may be a corrective or non-corrective lens. The iris simulating design  24  is generally annular in shape and is sized to cover or enhance a wearer&#39;s iris. The iris simulating design  24  may be opaque to partially or completely mask the wearer&#39;s iris or may be at least somewhat translucent so that some of the wearer&#39;s iris may show through the design. It is to be understood that the term “tinted” is intended to encompass both iris simulating designs of translucent and/or opaque pigmentations. Preferably, the iris-simulating design  24  is multi-colored and is more preferably comprised of four or more separate colors. A pad printing process is preferably used to print the iris-simulating design  24  on the lens substrate  22 . As described in greater detail below, four or more separate design portions (each preferably of a different color) are serially printed on the lens substrate  22  during the printing process. The design portions (colorant patterns) combine to form the multi-colored iris-simulating pattern  44 . 
     Generally speaking, two sub-processes are used for making the tinted contact lens  20 . The first sub-process is formation of a plurality of depressions  32 ,  34 ,  36 ,  38  (FIGS. 2 a-d ) in one or more printing plates (cliché s)  30 . The second sub-process is using the cliché(s)  30  in a pad printing process to transfer ink (or some other suitable fluent colorant) from the depressions to the lens substrate  22  (FIG.  1 ). Preferably, the ink is of a type well known in the tinted contact lens industry having binding properties enabling it to adhere to the lens substrate via a polymerization process. The ink may be opaque or translucent after being transferred to the lens substrate. 
     The first sub-process is generally indicated at  40  in the flow-chart of FIG.  3 . In the first step, represented by box  42 , an iris image is digitized into a computer. Digitizing the iris image may be accomplished by scanning a photograph or rendering of a human iris into the computer, or by use of a digital camera, or by using appropriate software to create an image by the computer itself. It is to be understood that the methods of digitizing an iris image mentioned herein are merely exemplary, and other methods of digitizing an iris image may be employed without departing from the scope of this invention. The digitized iris image may also comprise a hybrid image formed from different aspects of two or more iris images. The computer is preferably any commercially available computer having a suitable processor such as an Intel Pentium-3® processor. 
     As represented by box  44 , the colors of the digitized iris image are separated into selectively distinctive layers by use of commercially available software, such as Adobe Illustrator® or Adobe PhotoShop®. In practice, the iris image is comprised of thousands of tiny colored regions and the colors of the regions may encompass thousands of different colors. The iris image is preferably analyzed by a designer for determining where color separations are to be made. Preferably the image is separated into four, five, six, seven, eight, nine, ten, eleven, twelve, or more distinct color regions. Each color region is preferably mapped via a raster-based image editor, such as Adobe PhotoShop®. Each color region is then converted to grayscale and then converted to a halftone pattern (box  46 ). Each halftone pattern is then passed through a vector-based computer drawing program, such as Adobe Illustrator®. With the use of the drawing program, the halftone pattern (or digitized image portion) is adjusted and sized for export, preferably as an encapsulated postscript file, to a laser control unit of a suitable laser (indicated by box  48 ). Each digitized image portion comprises the combination of all of the tiny regions of the digitized iris image assigned to one of the selected color ranges. Preferably, the laser is a yttrium aluminum garnet (YAG) laser, such as an Electrox® Scriba II, commercially available from Electrox USA, Indianapolis, Ind. The laser control unit is preferably operated with suitable software, such as that commercially available from Electrox USA. The cliché  30  (e.g., FIG. 2 a ) is then aligned with the YAG laser. Referring to box  50 , the laser is then operated with appropriate aperture and power settings to meet the pattern width and depth requirements suitable to form the depressions  32 ,  34 ,  36 ,  38  in the portions of the cliché  30 . By adjusting the various power settings and/or incorporating multiple passes to the patterns, an operator is able to use the laser to vaporize finite layers of the plate conforming to the exact depression shapes desired. Preferably, the laser is operated using baselines of 2 kilohertz, aperture of 3.8 mm, yielding {fraction (5/1000)} particle beam, power at 70 watts, and speed frequency of 8 hits per second. 
     The laser forms each depression in an iris portion pattern to correspond to each digitized image portion. In other words, the digitized image portions combine to represent the digitized iris image, and the iris portion patterns of the depressions combine to represent the iris image to be printed on the contact lens substrate. As discussed above, FIGS. 2 a-d  show depressions  32 ,  34 ,  36 ,  38  formed in cliché portions. It is to be understood that the cliché portions may be portions of a single cliché or may be portions of multiple clichés. In other words, the depressions may all be formed in a single cliché  30  or may each be in a separate cliché without departing from the scope of this invention. 
     Use of a laser to form a depression in a cliché has several advantages over forming a depression by photo etching. To begin with, a depression formed with a laser is capable of greater resolution than a depression formed with a photo etching process. In particular, the resolution capabilities with the laser process is more than 9 times greater than that of the photo etching process. The corrosive nature of the photo etching process applied at higher resolution tends to completely obscure and break down the pattern&#39;s definition. The resolution limitation of the photo etching process creates barriers to achieve resolutions requiring increased color variations for multicolored contact lenses. By using a laser process to overcome the limitations in pattern resolution, a broader range of blending colors may be employed to create a tinted contact lens that provides a more natural appearance. 
     Another advantage of forming a depression with a laser rather than photo etching is elimination of the need to use toxic and hazardous chemicals, such as ferric nitrate, hydrochloric acid, and nitric acid. These chemicals increase chances of work related accidents or health issues. These chemicals are also hazardous to the environment and require EPA regulatory compliance for removal and disposal. Also, the unpredictability inherent in the photo etching process makes it difficult to produce depressions of desired depth. The desired depth of a typical depression used in a pad printing process to tint a contact lens is 17-25 microns. Depth variances with a photo etching process are generally ±3-5 microns. If the photo etching process does not achieve the desired depth, the pattern rendered is useless; the plate must be resurfaced and re-lapped and the complete process repeated. Conversely, if the pattern achieves too much depth (which is the tendency in the industry), the evaporation of the excess ink thinners/retardant and polymers are released into the air, thereby decreasing air quality. 
     Use of the laser process also increases the speed in which depressions may be formed in the cliché. In particular, the labor required to prepare a typical pattern in the cliché via a photo etching process is 3-6 man-hours. The labor to prepare such a pattern via the laser method of the present invention is less than one man-hour. Thus, use of the laser process results in a depression of greater resolution, reduces health risks and decreases cost of manufacture. 
     The second sub-process (i.e., transfer of ink from a depression in the cliché to the lens substrate  22 ) is schematically shown in FIGS. 4 a-e.  In FIG. 4 a , the cliché  30  is shown having a depression  32  flooded with ink  60 . A doctor blade  62  is swept across the cliché  30  to wipe the ink  60  from the cliché in a manner so that the ink is in only the depression. As shown in FIG. 4 b , a conventional pad-printing pad  64  is aligned with the depression  32  and pressed against the cliché  30  to pick up the ink in the depression. The pad  64  is then brought into registration (FIG. 4 c ) with a contact lens substrate  22  held on a lens holder  66  and then pressed (FIG. 4 d ) against the lens substrate to deposit the ink on the substrate in a pattern which constitutes a first design portion  70  of the iris simulating design (FIG.  1 ). The pad  64  is then released from the lens substrate  22  and the ink is allowed to dry. The first design portion  70  printed on the lens substrate  22  in this manner preferably has substantially the same shape as the pattern of the depression  32 . Although not shown, additional design portions are then serially printed on the lens substrate  22  by transferring ink from depressions  34  (FIG. 2 b ),  36  (FIG. 2 c ),  38  (FIG. 2 d ) in substantially the same manner as transferred from depression  32 . Preferably, different ink colors are used for each printing pattern. The design portions (colorant patterns) combine to form the multi-colored iris-simulating pattern  44 . 
     Although the iris-simulating pattern  44  has been described as being formed by the combination of four different colorant patterns printed on the contact lens substrate  22 , it is to be understood that more or fewer colorant patterns may be combined to form an iris-simulating pattern (e.g., three, five, six, seven, eight, nine, ten, eleven, twelve, or more colorant patterns) without departing from the scope of this invention. Preferably, however, four to twelve colorant patterns are printed on the lens substrate to form the iris simulating pattern. Also preferably, each colorant pattern is a different color. 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. 
     As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Technology Category: 7