Patent Publication Number: US-2022219465-A1

Title: Printing apparatus for printing directly onto containers

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 16/839,181, filed Apr. 3, 2020, the contents of all of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to printing apparatuses, and more particularly, to printing apparatuses configured to print directly onto a container. 
     BACKGROUND 
     Currently, there are printing apparatuses for printing onto containers in the marketplace. However, these printing apparatuses are configured to perform conventional printing on mostly flat labels or flat faces of containers. Printing directly onto curved surfaces of a container is difficult in as much as the distance from the print head and the surfaces change over a curved surface. For example, conventional print heads only dispense the ink a few millimeters if they are vertically positioned. Thus, the print head needs to be as close as possible to the surface of the container to retain print quality, e.g., the clearness of images or texts. If a distance greater than a few millimeters exists between the print head and the printing surfaces, which is often the case along a curved surface, the printing process may be difficult, and the print quality may not be satisfactory. 
     Accordingly, there exists a need for printing apparatuses to address effective printing on curved surfaces such as rounder curved surfaces. 
     SUMMARY 
     According to an embodiment of the present invention, a method and apparatus is provided for printing on a curved container surface. The apparatus includes a plurality of print heads configured to print directly on a curved surface of each of the plurality of containers and a plurality of container holders for retraining each of the plurality of containers. Each of the plurality of container holders is configured to rotate a container retained therewithin and to move the container linearly relative to the plurality print heads in a continuous motion to maintain a print location on the curved surface of each of the plurality of containers at a substantially constant perpendicular distance from each of the plurality of print heads during a printing process. 
     Additionally, in another embodiment, the print head may move to allow for printing on a round container. 
     These and other aspects of the present invention will be better understood in view of the drawings and following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a printing apparatus, according to an embodiment of the present invention; 
         FIG. 2  is a side view of a container holder of the printing apparatus in  FIG. 1 ; and 
         FIG. 3A-3E  are top views of a container and a print head of the printing apparatus in  FIG. 1 , as the container continuously moves and rotates during a printing process. 
         FIG. 4  is a top view of a printing apparatus in accordance with a further embodiment of the present invention. 
         FIG. 5  is a side view of the container holder of the printing apparatus of  FIG. 4 . 
         FIG. 6  is a schematic depiction of movement of the container about the turret during the printing process. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment of the present invention, referring to  FIG. 1 , there is shown a printing apparatus  10  configured to digitally print directly on the surfaces of a container  12  while the container  12  is in a continuous and constant motion. The printing apparatus  10  includes a plurality of print heads  14  for printing directly onto a curved surface  12   a  of the container  12  and a plurality of container holders  16  in a continuous automated operation. Each of the plurality of container holders  16  is configured to hold or retain the container  12  and is capable of providing both rotational movement and linear movement, as will be described in greater detail below. In the present illustrated embodiment, the containers  12  are shown as oval in general cross-section; but printing on containers having other non-flat cross-sectional shape is also contemplated. 
     Referring again to  FIG. 1 , the printing apparatus  10  further includes a printing wheel or turret  18  for rotating the containers  12  disposed within the plurality of container holders  16  about a turret vertical axis A, as will be described below, an infeed starwheel  20  is operable for transporting the containers  12  to the turret  18 , and a discharge starwheel  22  is operable for transporting the containers  12  from the turret  18 . 
     The circular turret  18  is configured to rotate in a counter-clockwise turret direction B about the turret vertical axis A with a constant speed. The turret  18  includes the plurality of container holders  16  mounted thereon for rotating the containers  12  to be printed. Each of the plurality of container holders  16  is disposed on the turret  18  with an evenly spaced distance therebetween. 
     A conveyor belt  24  moves in a longitudinal direction C and feeds the containers  12  to be printed to the infeed starwheel  20 . The infeed starwheel  20  rotates in a clockwise infeed direction D, which is opposing to the rotational direction of the turret  18 . Each of the containers  12  is transported to and retained in each corresponding container holder  16  via the infeed starwheel  20 . Once the printing on the surface  12   a  of the container  12  is completed, the printed container  12  is transported from the container holder  16  via the discharge starwheel  22 . The discharge starwheel  22  rotates in a clockwise discharge direction E, which is opposing to the rotational direction of the turret  18 . After exiting from the container holder  16 , the printed container  12  continuously moves on the conveyor belt  24  in the longitudinal direction C. 
     As noted above, the container  12  that may be used in connection with the present printing apparatus  10  has a shape with curved surfaces, e.g., oblong, oval, etc. Non-limiting examples of the container  12  to be printed include polyethylene terephthalate (PET) and high density polyethylene (HDPE), which may be made with monolayer or multilayer plastic materials. 
     Referring to  FIGS. 1 and 2 , the plurality of print heads  14  are arranged outside of the turret  18  and in close proximity to the turret  18  such that a nozzle dispensing path is substantially tangent to a moving direction (e.g., counter-clockwise turret direction B) of the curved surfaces  12   a  of the container  12  to be printed. Each of the plurality of print heads  14  is an inkjet print head having one or more nozzles  26  for dispensing printing ink. The one or more nozzles  26  are positioned such that they are substantially parallel with a container vertical axis F. In the depicted embodiment, each of the plurality of print heads  14  has one nozzle. Additionally, it is contemplated that the print head  14  is capable of moving horizontally to allow the curved printing surfaces  12   a  of the container  12  to be at a constant velocity during the printing process. As will be described in further detail with respect to the embodiment of  FIGS. 4-6 , this is also advantageous in printing on round containers. 
     Referring particularly to  FIG. 2 , each of the plurality of container holders  16  is configured to provide both rotational movement and linear movement during the printing process as each container holder  16  moves continuously along the counter-clockwise turret direction D, as will be described in greater detail below. 
     Each of the plurality of container holders  16  includes an upper slide  28  having an upper mandrel  30  mounted thereon, a lower slide  32  having a lower mandrel  34  mounted thereon. A rotary actuator  36  and a linear actuator  38  are employed to move the container  12  with respect to the print head  14 , as will be described in below. Non-limiting examples of the rotary actuator and linear actuator are server motor and stepper motor. 
     The container  12  is secured and retained within its corresponding container holder  16  by the upper mandrel  30  and the lower mandrel  34 , while moving along the counter-clockwise turret direction D and while being printed by the plurality of print heads  14 . Specifically, the upper mandrel  30  and lower mandrel  34  engage with a top end portion of the container  12  and a bottom end portion of the container  12 , respectively, such that each end portion of the container  12  is mounted onto the upper mandrel  30  and lower mandrel  34 . The upper mandrel  30  and lower mandrel  34  are located on the upper slide  28  and lower slide  30 , respectively, at a length from the plurality of the print heads  14  such that a consistent distance is maintained from the printing surfaces  12   a  of the container  12  to the plurality of print heads  14  during the printing process, as the container  12  rotates about the container vertical axis F. The container vertical axis F is parallel to the turret vertical axis A. 
     In the depicted embodiment, the lower mandrel  34  of each of the plurality of container holders  12  is operably connected to the rotary actuator  36 . The rotary actuator  36  is implemented under the lower slide  32  of the container holder  12 , as shown in  FIG. 2 , and the rotary actuator  36  provides rotational movement about the container vertical axis F during the printing process. The rotational movement ensures that during the printing process, the printed location of the printing surface of the container  12  is maintained substantially perpendicular to the stationary print head  14  during the printing process. Alternately, the rotary actuator  36  may be operably connected to the upper mandrel  30  of each of the plurality of container holders  12 . 
     The rotary actuator  36  is configured such that it allows the container  12  to be rotated in either a counter-clockwise direction G or clockwise direction H with various desired degrees (e.g., up to 360 degrees). In the depicted embodiment, as shown in  FIG. 3 , the container  12  rotates about the container vertical axis F in the counter-clockwise direction G. 
     The linear actuator  38  is included in each of the plurality of container holders  16  for providing linear movement (toward and away from the print head  14 ) of the container holder  16 . The linear actuator  38  is integrally connected to the lower slide  32  (which is connected to the upper slide  28  via a connecting bar  40 ) and disposed between the lower slide  32  and a top surface of the turret  18 , as shown in  FIG. 2 . During the printing process, as the turret  18  continuously rotates at a constant speed and as the container  12  rotates, the linear actuator  38  allows the container  12  to move towards and away from the print head  14  along a line I. The linear movement combined with rotational movement allows a consistent distance to be retained from the printing surface of the container  12  to the print head  14 , as the container  12  rotates and moves continuously along the moving direction (e.g., counter-clockwise turret direction D). 
     Referring to  FIGS. 3A-3E , the printing process on the printing surfaces of the container  12  will be described. In the depicted embodiment, each container holder  16  having the container  12  therewithin enters a printing area with one side of the printing surface initially contacting with the nozzle  26  of the printing head  14 , as shown in  FIG. 3A . Due to the curved printing surfaces  12   a  of the container  12 , the printing apparatus  10 , specifically the container holder  16 , is configured to rotate about the container vertical axis F as the printing on the container  12  progresses. As the container  12  is rotated about the container vertical axis F in the counter-clockwise direction G at an angular speed with the turret  18  being continuously moving in the counter-clockwise turret direction D, the nozzle  26  of the print head  14  dispenses the ink jet and prints directly on the curved printing surfaces  12   a  of the container  12  until the entire printing surface is printed in a desired fashion, as shown in  FIG. 3B-3E . While the container  12  is being rotated during the printing process, the linear actuator  38  of the container holder  16  moves the container  12  towards and away from the nozzle  26  of the printing head  14  along the line I to maintain a consistent distance from the printing surfaces of the container  12  to the print head  14 , allowing the printed materials on the curved surfaces to be in a good print quality (e.g., the clearness of images or texts). 
     The printing process is continuous until the entire desired printing surface  12   a  of the container  12  is printed by the printing head  14  in one continuous motion. The print head  14  completes the printing process as the other side of the printing surface of the container  12  is reached, as shown in  FIG. 3E . During the printing process, the print head  14  may remain stationary or move horizontally with respect to the turret  18  as the container  12  rotates about the container vertical axis F and moves linearly towards and away from the print head  14  to maintain a substantially constant distance between the print head  14  and the location of printing on the curved surface. The rotational movement and linear movement of the container  12  ensure that the location of printing on the curved surfaces  12   a  of the container  12  remains generally perpendicular to the print head  14  as the container  12  rotates during the printing process. 
     Accordingly, the combination of the rotational movement of the turret  18 , the rotational movement of container  12 , and the linear movement of container  12  provides a printing technique that may be achieved rapidly and continuously, and vastly improves printing quality on curved printing surfaces of the container  12 . 
     From the foregoing, it will be appreciated that a printing apparatus according to the present invention provides a printing technique for directly printing on a container and improving printing quality on the curved printing surfaces of the container. 
     Referring now to  FIGS. 4-6 , a further embodiment of the present invention is shown which is particularly advantageous in printing on round bottles. 
     The present embodiment is substantially similar to the embodiment described above. For simplicity, with respect to the present embodiment, similar reference numerals will be used to denote similar elements. 
     The printing apparatus  110  of the present embodiment includes a plurality of print heads  114  for printing directly onto a curved surface  112   a  of a container  112  held on a plurality of container holders  116  ( FIG. 5 ) in a continuous automated operation. Each of the container holders  116  is configured to hold and retain a container  112  and is capable of providing both rotational movement and linear movement similar to that described above. 
     In the present illustrative embodiment, containers  112  are shown to be round containers in cross section. However, the present embodiment is not limited thereto. 
     As with the above embodiment, the present embodiment of the printing apparatus  110  includes a wheel or turret  118  for rotating the containers  112  around an axis A in the direction of arrow B. An infeed star wheel  120  is operable for transporting the containers  112  to the turret  118  and a discharge star wheel  122  is operable for transporting the containers  112  from the turret  118 . A conveyor belt  124  moves in a longitudinal direction C and feeds the containers  112  to be printed into the infield star wheel  120 . The discharge star wheel  122  accepts the printed containers and after exiting from the container holder  116 , the printed containers  112  continuously move on a conveyor belt  124  in the longitudinal direction C. The operation of the conveyor belt, turret and star wheels are substantially similar to that described above with respect to the previous embodiment. 
     Referring additionally to  FIG. 5  specifically, each of the plurality of container holders  116  is configured to provide both rotational movement and linear movement during the printing process. 
     The construction and movement of the container holders  116  is substantially similar to that described above with respect to  FIG. 2 . Each container holder  116  includes an upper slide  128  with an upper mandrel  130  mounted thereto, a lower slide  132  having a lower mandrel  134  mounted thereto. 
     A rotary actuator  136  and a linear actuator  138  are employed to move the container  112  with respect to the print head  114  in a manner similar to that described above with respect to  FIG. 2  during the printing process. As the turret  118  continuously rotates preferably, but not necessarily, at a constant speed and as container  112  rotates, the linear actuator  138  allows the container to move towards and away from the print head (arrow R in  FIG. 4 ). The linear movement combined with the rotational movement allows a constant distance to be maintained between the printing surface of the container  112  and the print head  114  as the container rotates and moves continuously along the moving direction. While a rotary and linear actuator are described, the same movement may be accomplished via servo motor, stepper motor, cams, pneumatics, etc. 
     In addition, with respect to round bottles, it is has been found that constant distance between the printing surface of container  112  and the print head may be further facilitated by arranging the print head  114  to be movable in a back and forth linear direction L as the container rotates about turret  118 . 
     Different from the embodiment shown in  FIG. 2 , the embodiment of  FIG. 5  mounts the print head  114  for longitudinal movement generally along the path of the container holder  116  about turret  118  as indicated by double headed arrows L in  FIGS. 4-6 . In  FIG. 5  the movement is into and out of the page. 
     Referring specifically now to  FIG. 6 , the printing process for printing on surfaces  112   a  of round containers  112  may be described. While substantially similar to that described above with respect to  FIGS. 3A-E , in this embodiment the printing process incorporates movement of the print head  114  along with movement of the container holder  116 . 
     Each container  112  supported on the container  116  holder enters a printing area so that one point of the surface  112   a  of container  112  is positioned adjacent nozzle  126  of printing head  114 . A center line C defines a neutral position for the print head along path L. As shown in  FIG. 6 , the print head is initially positioned at a location to the left a distance of D 1  from the center line C. At this position, the container  112  on the container holder  116  is positioned fully extended toward the circumference of the turret  118  defined as r 1  in  FIG. 6 . This defines position (1) where the nozzle  126  is a distance P from container surface  112   a . As the container  112  moves about the turret and is rotated counter-clockwise by the container holder  116 , the print head  114  prints on the surface  112   a  of the container. The container  112  also retracts away from the circumference of the turret from its fully extended position r 1  to a position r 2  (which is less than r 1 ) defining position (2) where at that point the container  112  has been printed on 90° of the container surface  112   a . The print head  114  moves along path L with the movement of container so as to maintain the constant distance P between the print head  114  and the container  112 . When the container is retracted to r 2  the print head has moved to the right to a positon which is a distance D 2  (less than D 1 ) from the center line C. 
     As the container  112  continues to move about the turret  118 , it is retracted further to a position r 3  which less than r 2  defined at position (3). Since the container  112  is continually rotating in a counter-clockwise direction, the container  112  will be printed on 180° of the container surface at position (3). 
     The print head will now be moved along path L to a distance D 3  which is at the center line C so as to maintain the constant distance P. 
     The container  112  continues to move about the turret  118  from the positon (3) to (4) where, due to the counter-clockwise rotation, the container is now printed on 270° of the container. To maintain the constant distance P, the container is extended to r 4  which is equal to r 2  and the print head moves back to a position which is a distance D 4  from center line C which is equal to distance D 2  but in the opposite direction. 
     Still further, the container moves along the turret to a position (5) where the container is extended to a radius r 5  which is equal to r 1 . As the container continues its counter-clockwise revolution it is now printed on 360° of the container. Similarly, the print head has now moved a distance D 5  which is equal to distance D 1 , but in the opposite direction so as to maintain the constant distance P between the print head and the container D. 
     While the present embodiment shows printing 360° about the container  112 , it may be appreciated that printing may take place on less than the entire circumference of the container. 
     Thus by movement of the container toward and away from the circumference of the turret while rotating the container and by movement of the print head a relatively constant distance is maintained between the print head and the container surface during printing. 
     In general, the foregoing description is provided for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. Rather, those skilled in the art will appreciate that additional modifications, as well as adaptations for particular circumstances, will fall within the scope of the invention as herein shown and described and of the claims appended hereto.