Ink-jet printing system for printing colored images on contact lenses

Abstract

The present invention provides a method for making colored contact lenses and an apparatus for implementing the method of the invention. The apparatus of the invention comprises a securing means for holding a contact lens or a portion of a mold for making the contact lens, a printer head, wherein the printer head comprises one or more nozzles each of which is capable of jetting droplets of color liquid independent of each other under control of a computer system; a positioning means for precisely positioning the printer head at each of a plurality of predetermined positions, one at a time, on a surface of the contact lens or the mold portion under control of the computer system. The method and apparatus of the invention are useful for producing colored contact lenses having high quality color images thereon.

What is claimed is:  
     
         1 . A printing apparatus for making colored contact lenses, comprising: 
 (1) a securing means for holding a contact lens or a portion of a mold for making the contact lens;    (2) a printer head, wherein the printer head comprises one or more nozzles each of which is capable of jetting droplets of color liquid independent of each other under control of a computer system;    (3) a positioning means for precisely positioning the printer head at each of a plurality of predetermined positions, one at a time, on a surface of the contact lens or the mold portion under control of the computer system.    
     
     
         2 . A printing apparatus of  claim 1 , further comprising at least one additional printer head having one or more nozzles, wherein each nozzle is capable of jetting droplets of color liquid independent of each other under control of the computer system.  
     
     
         3 . A printing apparatus of  claim 1 , wherein the printer head comprise at least one column of nozzles  
     
     
         4 . A printing apparatus of  claim 3 , wherein the positioning means is a motor assembly, wherein the motor assembly moves the contact lens or the mold portion or the printer head along a translational axis, rotates the contact lens or the mold portion or the printer head around a rotational axis that passes through the apical center of the surface of the contact lens or the mold portion in a direction normal to the surface of the contact lens or the mold portion, and tilts the contact lens or the mold portion or the printer head with respect to the rotational axis.  
     
     
         5 . A printing apparatus of  claim 3 , wherein the positioning means is a motor assembly that can move the contact lens or the mold portion (or the printer head) toward to or away from the printer head (or the contact lens or the mold portion) and can rotate the contact lens or the mold portion (or the printer head) around a rotational axis that passes through the apical center of the surface of the contact lens or the mold portion in a direction normal to the surface of the contact lens or the mold portion.  
     
     
         6 . A printing apparatus of  claim 5 , wherein the column of nozzles covers at least width of an annulus zone on the surface of the contact lens or the mold portion, wherein the center of the annulus zone is the apical center of the surface of the contact lens or the mold portion, wherein a printing area is located within the annulus zone.  
     
     
         7 . A printing apparatus of  claim 6 , wherein the printer head is tilted at an angle with respect to the rotational axis so that the printing surface of the printer head is in parallel with a surface tangent to the annulus zone.  
     
     
         8 . An apparatus of  claim 7 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the surface of the contact lens or the mold portion.  
     
     
         9 . An apparatus of  claim 5 , wherein the printer head is placed perpendicular to the rotational axis, wherein the column of nozzles covers at least the diameter of a circular zone on the surface of the contact lens or the mold portion, wherein the center of the circular zone is the apical center of the surface of the contact lens or the mold portion, wherein a printing area is located within the circular zone.  
     
     
         10 . An apparatus of  claim 9 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the surface of the contact lens or the mold portion.  
     
     
         11 . A printing apparatus of  claim 3 , wherein the positioning means comprises: 
 a moving means, wherein the moving means can move the contact lens or the mold portion (or the printer head) at a constant velocity under the printer head (or over the contact lens or the mold portion); and    a jetting-controlling means for controlling each of the nozzles to dispense drops of color liquid in a timed sequence, wherein time intervals between two drops from each of the nozzles are constant or variable.    
     
     
         12 . An apparatus of  claim 11 , wherein the printer head is placed perpendicular to a rotational axis that passes through the apical center of the surface of the contact lens or the mold portion, wherein the column of nozzles covers at least the diameter of a circular zone on the surface of the contact lens or the mold portion, wherein the center of the circular zone is the apical center of the surface of the contact lens or the mold portion, wherein a printing area is located within the circular zone.  
     
     
         13 . A printing apparatus of  claim 12 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the surface of the contact lens or the mold portion.  
     
     
         14 . A method for printing a color image on an article having a curved surface, comprising under control of a computer system: 
 (a) positioning precisely a printer head at each of a plurality of predetermined positions, one at a time, on the curved surface of the article while keeping a relatively constant distance between the printer head and the curved surface of the article, wherein the printer head comprises one or more nozzles each of which is capable of jetting droplets of color liquid independent of each other; and    (b) dispensing one or more drops of color liquid from the printer head, one drop from one nozzle, on the curved surface of the article at each of the predetermined positions so as to produce the color image on the curved surface of the article.    
     
     
         15 . A method of  claim 14 , wherein the article is a contact lens or a portion of a mold for making the contact lens, wherein the mold portion defines the anterior or posterior surface of the contact lens.  
     
     
         16 . A method of  claim 15 , wherein the printer head comprise at least one column of nozzles.  
     
     
         17 . A method of  claim 16 , wherein the positioning step comprising: 
 keeping the printer head (or the article) stationary; moving linearly the article (or the printer head) along a translational axis;    rotating the printer head (or the article) around a rotational axis that passes through the apical center of the curved surface of the article in a direction normal to the curved surface; and    tilting the rotational axis.    
     
     
         18 . A method of  claim 16 , wherein the positioning step comprises: 
 moving linearly the article (or the printer head) toward to or away from the printer head (or the article); and    rotating the article (or the printer head) around a rotational axis that passes through the apical center of the curved surface of the article in a direction normal to the curved surface.    
     
     
         19 . A method of  claim 16 , wherein the positioning step comprises: 
 moving the article (or the printer head) at a constant velocity directly under the printer head (or above the article); and    generating jetting-control signals to control each of the nozzles to dispense a plurality of drops of color liquid in a timed sequence, one drop at a time and at a constant or variable time interval between two subsequent drops.    
     
     
         20 . A method of  claim 16 , further comprising a step of converting a two dimensional color image into a set of printing-control signals for printing the color image on the curved surface of the article, wherein the two and three dimensional color images are represented by a matrix of discrete and/or blended color dots.  
     
     
         21 . A method of  claim 20 , wherein the density of dots is kept constant by adding and/or deleting dots in the dot matrix of the three-dimensional color image in the step of converting the two-dimensional color image into the three dimensional color image.  
     
     
         22 . A method of automatically printing color images on articles each having a curved surface, comprising: 
 (1) continuously transporting the articles along a predetermined path to transport each of the articles, one at a time, into a printing station comprising a printer head having one or more nozzles for jetting droplets of color liquid;    (2) each time one of the curved articles moves into the digital printing system, 
 (a) activating a positioning means to position precisely the printer head at each of a plurality of predetermined positions, one at a time, on the curved surface of the article, and  
 (b) dispensing one or more drops of color liquid, one drop from one nozzle, on the curved surface of the article at each of the predetermined positions so as to print a color image on each of the articles.  
   
     
     
         23 . A method of  claim 22 , wherein the transporting step includes the steps of: positioning each of the articles in a respective location in a carrier and continuously moving the carrier along the predetermined path.  
     
     
         24 . A method of  claim 23 , wherein the activating step includes the steps of: generating a start signal each time one of the articles moves into the printing station and transmitting the start signal to a computer system to activate the positioning means to precisely position the printer head on the curved surface of the article.  
     
     
         25 . A method of  claim 24 , wherein the articles are contact lenses or mold portions for making the contact lenses.  
     
     
         26 . A method of  claim 25 , wherein the printer head comprise at least one column of nozzles, wherein each of the column of nozzles ejects droplets of color liquid independent of each other under control of the computer system.  
     
     
         27 . A method of  claim 26 , wherein the step of precisely positioning the printer head on the curved surface of the article comprising: 
 keeping the printer head (or the article) stationary;    moving linearly the article (or the printer head) along a translational axis;    rotating the printer head (or the article) around a rotational axis that passes through the apical center of the curved surface of the article in a direction normal to the curved surface; and    tilting the rotational axis.    
     
     
         28 . A method of  claim 26 , wherein the step of precisely positioning the printer head on the curved surface of the article comprising: 
 moving linearly the article (or the printer head) toward to or away from the printer head (or the article); and    rotating the article (or the printer head) around a rotational axis that passes through the apical center of the curved surface of the article in a direction normal to the curved surface.    
     
     
         29 . A method of  claim 26 , wherein the step of precisely positioning the printer head on the curved surface of the article comprising: 
 moving linearly the article (or the printer head) at a constant velocity directly under the printer head (or above the article); and    generating jetting-control signals to control each of the nozzles to dispense a plurality of drops of color liquid in a timed sequence, one drop at a time and at a constant or variable time interval between two subsequent drops.    
     
     
         30 . A system for automatically printing color images on articles each having a curved surface, comprising: 
 (1) at least one printing station comprising a printer head having one or more nozzles each of which is capable of ejecting droplets of colored liquid independent of each other, a positioning means to precisely position the printer head at each of a plurality of predetermined positions, one at a time, on the curved surface of each of the articles;    (2) transporting means to move the articles along a predetermined path to transport each of the articles, one at a time, into the printing station; and    (3) a computer system for controlling operation of the printing station and the transporting means.    
     
     
         31 . A system of  claim 30 , wherein the transporting means includes a carrier for holding one or more articles.  
     
     
         32 . A system of  claim 31 , wherein the transporting means further includes an activating means for detecting if one article is moved into the printing station and for generating and transmitting a start signal to a computer system to activate the positioning means to precisely position the printer head on the curved surface of the article.  
     
     
         33 . A system of  claim 32 , wherein the articles are contact lenses or mold portions for making the contact lenses.  
     
     
         34 . A system of  claim 33 , wherein the printer head comprise at least one column of nozzles.  
     
     
         35 . A system of  claim 34 , wherein the positioning means is a motor assembly, wherein the motor assembly moves the article or the printer head along a translational axis, rotates the article or the printer head around a rotational axis that passes through the apical center of the curved surface of the article, and tilts the article or the printer head with respect to the rotational axis.  
     
     
         36 . A system of  claim 34 , wherein the positioning means is a motor assembly that can move linearly the article (or the printer head) toward to or away from the printer head (or the article) and can rotate the article (or the printer head) around a rotational axis that passes through the apical center of the curved surface of the article.  
     
     
         37 . A system of  claim 36 , wherein the column of nozzles covers at least width of an annulus zone on the surface of the article, wherein the center of the annulus zone is the apical center of the curved surface of the article, wherein a printing area is located within the annulus zone.  
     
     
         38 . A system of  claim 37 , wherein the printer head is tilted at an angle with respect to the rotational axis so that the printing surface of the printer head is in parallel with a surface tangent to the annulus zone.  
     
     
         39 . A system of  claim 38 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the curved surface of the article.  
     
     
         40 . A system of  claim 36 , wherein the printer head is placed perpendicular to the rotational axis, wherein the column of nozzles covers at least the diameter of a circular zone on the curved surface of the article, wherein the center of the circular zone is the apical center of the curved surface of the article, wherein a printing area is located within the circular zone.  
     
     
         41 . A system of  claim 40 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the curved surface of the article.  
     
     
         42 . A system of  claim 34 , wherein the positioning means comprises: 
 a moving means, wherein the moving means can move the article (or the printer head) at a constant velocity under the printer head (or above the article); and    a jetting-controlling means for controlling each of the nozzles to dispense drops of color liquid in a timed sequence, wherein time interval between two drops from each of the nozzles is constant or variable.    
     
     
         43 . A system of  claim 42 , wherein the printer head is placed perpendicular to a rotational axis that passes through the apical center of the curved surface of the article, wherein the column of nozzles covers at least the diameter of a circular zone on the curved surface of the article, wherein the center of the circular zone is the apical center of the curved surface of the article, wherein a printing area is located within the circular zone.  
     
     
         44 . A system of  claim 43 , wherein the printing surface of the printer head has a curvature accommodating the curvature of the curved surface of the article.