Patent Application
20090166905
1. Field of the Invention
The present invention relates generally to the fabrication of contact lenses and more particularly to a contact lens fabrication method and tool that uses a supplementary tool to match with a mold for molding a contact lens for enabling the finished contact lens to be directly packaged with the supplementary tool, saving much labor and time.
2. Description of the Related Art
In 1508, Leonard da Vinci first has the idea of placing a corrective lens directly onto the surface of the eye. In 1636, Rene Descartes proposed another idea in which a glass tube filled with liquid is placed in direct contact with the cornea. In 1887, Adolf Eugen Fick, a German physiologist, created the first successful contact lens. Glass-blown scleral lenses remained the only form of contact lens until the 1938 when polymethyl methacrylate (PMMA) was developed, Mullen and Obring use the plastic scleral lenses to manufacture. Obring developed Plexiglass series in New York in 1940. In 1961, Czech chemist Otto Wichterle invented soft contact lenses. In 1970, RGP (rigid gas-permeable) contact lenses were developed, and widely invited for the advantages of small diameter (about 9 mm) and gas permeability. In 1999, an important development was the launch of the first silicone hydrogels onto the market. These new materials have extremely high oxygen permeability with comfort performance.
Currently, there are three of contact lens fabrication methods been adopted, i.e., the latche cutting method, the cast molding method and the spin casting method. Either of the aforesaid three contact lens fabrication methods is used, the finished contact lenses must be dipped in a buffer solution to become soft, and then respectively packaged in an individual contact lens case for sale. These conventional contact lens fabrication methods are still not perfect because of the following drawbacks:
1. When the lathe cutting method is employed, the molten contact lens material is filled in a glass tube and then cured under a high temperature environment, and then the cured contact lens material stick thus obtained forms a circular raw lenses, and then the circular raw lenses are milled, ground and polished, and then the polished contact lenses are dipped in a buffer solution, and then the softened contact lenses are individually packaged. This fabrication method is complicated, requiring much labor and time. Further, a small mistake occurs during the fabrication, the fabrication must be stopped, and the defective rate may be greatly increased.
2. When the cast molding method is employed, the molten contact lens material is filled in between the bottom and top dies of the mold and cured by means of the application of a high pressure and a high temperature, and then each cured raw contact lens is ground and polished, and then each polished contact lens is dipped in a buffer solution, and then each softened contact lens is individually packaged. This fabrication has the same drawbacks of high consumption of labor and time and high defective rate, and therefore the manufacturing cost is high.
3. When the spin casting method is employed, the molten contact lens material is filled in a spinning mold, and caused by centrifugal force to spread in the cavity of the spinning mold evenly, and the contact lens material is then cured subject to the radiation of ultraviolet light, and then each raw contact lens thus obtained is ground and polished, and then each polished contact lens is dipped in a buffer solution, and then each softened contact lens is individually packaged. This fabrication method is also complicated. Only a skilled person can operate the fabrication equipment. In case of unstable spinning, the thickness of the contact lens thus made becomes uneven, and the optical axis of the contact lens may bias from the center.
4. The application of either of the aforesaid conventional contact lens fabrication methods requires a respective specially designed mold. When each contact lens is cured, it must be ground and polished, complicating the fabrication and increasing the risk of high defective rate. Therefore, these conventional contact lens fabrication methods cannot lower the contact lens manufacturing cost.
Therefore, it is desirable to provide a contact lens fabrication method and tool that eliminates the aforesaid drawbacks.
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a contact lens fabrication method and tool that simplifies the fabrication of contact lenses and improves the yield rate, and effectively lowers the manufacturing cost.
To achieve this and other objects of the present invention, the contact lens fabrication tool comprises a mold and a supplementary tool. The mold comprises a cavity that curves smoothly inwards, and a cut angle of sharp edge extending around the border of the cavity. The supplementary tool comprises a downwardly extending work space fitting the mold, a male molding block curved smoothly downwards in the work space for insertion into the cavity of the mold to squeeze a contact lens material into shape, a sloping bearing surface extending around the periphery of the male molding block, and a sealing plane extending around a bottom side of the work space for the bonding of a sealing film to seal a buffer solution in the work space after molding of a contact lens and removal of the molded contact lens with the supplementary tool from said mold.
The contact lens fabrication method uses the aforesaid contact lens fabrication tool. The method includes the step of pressing the male molding block of the supplementary tool into the cavity of the mold to squeeze a contact lens material into shape and to simultaneously cut off an excessive part of the contact lens material from the shape formed contact lens by means of the cut angle of sharp edge of the mold and the sloping bearing surface of the supplementary tool, and the step of curing the contact lens, the step of separating the supplementary tool from the mold to have the contact lens be adhered to the surface of the male molding block, the step of filling a buffer solution into the supplementary tool to have the contact lens be dipped in the buffer solution after quality examination of the contact lens, and the step of sealing a sealing film to the supplementary tool to form a finished contact lens product for sale.
For the fabrication of a color contact lens, a transfer printing technique or spray printing technique is employed to print the surface of the cavity of the mold with a color printing ink before putting a contact lens material into the cavity of the mold.
Referring to
The mold 1 has a cavity 11 that curves smoothly inwards and has a cut angle of sharp edge 111 on the border, a plurality of locating blocks 12 arranged around the cut angle of sharp edge 111, and an air filling hole 13 disposed beyond but in air communication with the cavity 11 for the injection of compressed air into the cavity 11. The air filling hole 13 may be not requisite.
The supplementary tool 2 comprises a downwardly extending work space 22 fitting the mold 1, a male molding block 21 curved smoothly downwards in the work space 22 and fitting the curvature of the cavity 11, a sloping bearing surface 211 extending around the periphery of the male molding block 21, a sealing plane 23 extending around the bottom side of the work space 22, and a flat panel 24 outwardly extending from the sealing plane 23.
During the use of the aforesaid contact lens fabrication tool, contact lens material 3 is put in the cavity 11 of the mold 1, and then the supplementary tool 2 is operated to force the male molding block 21 into the cavity 11 of the mold 1. At this time, the downward pressure from the male molding block 21 causes the contact lens material 3 to spread out evenly in the cavity 11 and also to spread over the cut angle of sharp edge 111 into the space outside the cavity 11 around the locating blocks 12 and within the work space 22. When increasing the pressure that is being applied to the male molding block 21 against the cavity 11 of the mold 1, the connection portion between the sloping bearing surface 211 and the male molding block 21 acts against the cut angle of sharp edge 111, thereby cutting off waste material of overflowed part 32 of the contact lens material 3 that is beyond the cut angle of sharp edge 111. By means of the application of a heating process, the shape-formed contact lens material 3 is cured, forming a contact lens 31. Thereafter, the supplementary tool 2 is separated from the mold 1 (see
According to the contact lens fabrication method of the present invention, one mold 1 is provided, and individual supplementary tools 2 are pressed into the mold 1 one after another to mold one respective piece of contact lens material 3 into shape and to carry the respective contact lens 31 away from the mold 1 for further examination, filling of buffer solution 4, sealing and sterilization. This contact lens fabrication method saves much labor and time, effectively improving the yield rate and lowering the manufacturing cost.
The process of curing the shape-formed contact lens material 3 into a contact lens 31 can be done by means of the radiation of ultraviolet light or the application of a heating process. The contact lens material 3 can be a hydrogel polymer, UV (ultraviolet) solidified polymer or thermosetting polymer. The sealing film 5 can be an aluminum foil, tin foil or thin polymer film.
Further, the smoothly curved surface of the male molding block 21 of the supplementary tool 2 is a surface treated through a corona treatment, flame treatment or UV (ultraviolet) treatment, enhancing its surface adherence strength for the contact lens 31.
Referring to
As stated above, the process of curing the contact lens material 3 can be done by means of the radiation of ultraviolet light or the application of a heating process. The contact lens material 3 can be a hydrogel polymer, UV solidified polymer, or thermosetting polymer. Further, the sealing film 5 can be an aluminum foil, tin foil or thin polymer film. Further, the smoothly curved surface of the male molding block 21 of the supplementary tool 2 is treated with a surface treatment such as corona treatment, flame treatment or ultraviolet treatment to enhance its surface adherence strength for the contact lens 31.
During the aforesaid contact lens fabrication process, a plastic transfer-printing head 6 is used and dipped in a color printing ink 62 carried on a steel ink pad 61 for transfer-printing the color printing ink 62 on the surface of the cavity 11 of the mold 1. Alternatively, a spray printing technique may be employed to spray print the color printing ink 62 on the surface of the cavity 11 of the mold 1, or to spray printing the color printing ink 62 on the surface of the shape-formed contact lens material 3 after the curing process.
The process of curing the color contact lens 33 can be done by means of the radiation of ultraviolet light or the application of a heating process. The contact lens material 3 can be a hydrogel polymer, UV solidified polymer or thermosetting polymer. Further, the sealing film 5 can be an aluminum foil, tin foil or thin polymer film. Further, the smoothly curved surface of the male molding block 21 of the supplementary tool 2 is treated with a surface treatment such as corona treatment, flame treatment or ultraviolet treatment to enhance its surface adherence strength for the color contact lens 33.
As stated above, the process of curing the contact lens material 3 can be done by means of the radiation of ultraviolet light or the application of a heating process. The contact lens material 3 can be a hydrogel polymer, UV solidified polymer or thermosetting polymer. Further, the sealing film 5 can be an aluminum foil, tin foil or thin polymer film. Further, the smoothly curved surface of the male molding block 21 of the supplementary tool 2 is treated with a surface treatment such as corona treatment, flame treatment or ultraviolet treatment to enhance its surface adherence strength for the cured contact lens 31.
As stated above, the invention uses the supplementary tool 2 and the mold 1 to mold contact lens material 3 into shape, and the shape formed contact lens 31 is cured, and then a buffer solution 4 is filled in the supplementary tool 2 and packaged with the contact lens 31 and the supplementary tool 2 for sale. This fabrication method greatly saves the labor and time, effectively improving the yield rate and lowering the manufacturing cost.
In conclusion, the contact lens fabrication method and tool of the present invention has the following advantages of features:
1. The supplementary tool 2 and the mold 1 are used to mold a contact lens material 3 into a contact lens 31 (or a color contact lens 33) and then cured in the supplementary tool 2, and then a buffer solution 4 is filled in the supplementary tool 2 and packaged with the contact lens 31 (or the color contact lens 33) and the supplementary tool 2 for sale. Therefore, the invention greatly simplifies the fabrication of a contact lens and improves the yield rate, and effectively lowers the manufacturing cost.
2. After curing of the contact lens 31 (or the color contact lens 33) in the supplementary tool 2, the supplementary tool 2 is directly used as a package material to package the contact lens 31 (or the color contact lens 33), saving much the cost.
3. After formation of the contact lens 31 (or the color contact lens 33), the waste material of overflowed part 32 of the contact lens material 3 is separated from the contact lens 31 (or the color contact lens 33) and secured to the locating blocks 12 in the mold 1 beyond the cavity 11. Therefore, the waste material of overflowed part 32 does not hinder the formation the contact lens 31 (or the color contact lens 33).
Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.
