Rotary system and method for printing containers

A system for digitally printing directly on a plurality of containers is provided. In an embodiment, the system includes a device configured to determine an initial position or orientation of an individual container; a plurality of print heads configured to print directly on said containers; and a plurality of container holders configured hold or retain an individual container, to rotate the individual container, and to maintain a rotational position of the individual container relative to at least one print head while printing occurs; and one or more curing devices. The system may be configured such that the plurality of container holders are configured to move along a linear or curved path, and the plurality of container holders may be configured to controllably rotate about a container axis.

TECHNICAL FIELD

The present invention relates to plastic containers having digital images printed thereon, including curved plastic containers.

BACKGROUND

Conventional techniques for printing onto curved plastic containers are subject to challenges. For example, it can be difficult to obtain proper registration between colors, and changing images, designs or wording can be expensive and time consuming.

Inkjet printing with multiple nozzles is often useful with flat surfaces. However, it can be difficult to satisfactorily use multiple nozzles on round, curved, and/or non-cylindrical print surfaces, particularly such surfaces when higher-speed operations are involved.

It is desirable to print a digitally generated image directly onto a plastic container, particularly a curved and/or non-cylindrical surface of a plastic container, wherein the printing can be accomplished with acceptable quality, and at a reasonable speed and cost.

SUMMARY

The present disclosure provides, inter alia, a system for digitally printing directly on a plurality of containers. In an embodiment, the system includes a device configured to fix or determine an initial position or orientation of an individual container; a plurality of print heads configured to print directly on said containers; a plurality of container holders, which may be configured hold or retain an individual container, to rotate the individual container, and to maintain a rotational position of the individual container relative to at least one print head while printing occurs; and one or more curing devices. The system may be configured such that the plurality of container holders are configured to move along a path (e.g., a curved or linear path), and the plurality of container holders may be configured to controllably rotate about a container axis. In some embodiments the system may be configured so that the containers are mechanically oriented, and may be self-orienting by mechanical means, with or without employing vision or scanning.

Further features and aspects of the present disclosure are discussed hereinbelow.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the present invention, examples of which are described herein and illustrated in the accompanying drawings. While the invention will be described in conjunction with embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention.

A top plan view of an embodiment of a rotary system5is generally illustrated inFIG. 1. The rotary system5is configured to print one or more digital images on a plurality of containers10. As generally illustrated, the rotary system5may be configured to move the containers10—for example, in a rotary or curved path—about or around a central rotary position (generally labeled15). With embodiments of the disclosure, the rotary system5generally has an operational radius (e.g., a radius or curved path about a position, such as central rotary position15) and the containers also have a radius (about a longitudinal axis of the individual container). Further, a radius associated with the surface of a container to be printed may be constant or non-constant. Embodiments of the rotary system5may be configured to account for both the system operational radius (which can generally be constant) and the container radius (which may be constant or non-constant), so that during printing a print head (which can be substantially stationary or movable) will have or maintain a substantially constant stand-off distance with respect to the surface of the container to be printed.

By way of example and without limitation, an embodiment of a container that may be used in connection with the present disclosure is generally shown inFIG. 2. The illustrated container10includes portions that are non-cylindrical—e.g., the portion including a surface representation of a leaf12. Without limitation, the container10may, for example, comprise a plastic injection molded or blow molded container. The container may also, without limitation, be comprised of a wide variety or monolayer or multilayer plastic materials, such as polyethylene terephthalate (PET) or high density polyethylene (HDPE).

In embodiments, the containers10may each be received within or otherwise retained by a container holder. The container holder20may be provided in a variety of forms, and may, if desired, comprise a base cup-type holder. For other embodiments of the rotary system5, other portions of the container (e.g., upper/neck portion) may be held or retained—whether in addition to or in lieu of holding or retaining a base portion of the container. Without limitation, examples of base cup-type holders are generally shown as holders20inFIGS. 1 and 3. The container holder may simply hold or retain the container10during the printing operation associated with the system, or, if desired, the container holder may additionally provide supplemental processing associated with the base of the container, e.g., may provide heat or thermal shaping to portions of the container.

In an embodiment, for example and without limitation, as generally illustrated inFIGS. 3 and 4, a container holder20′ may be configured to hold or retain a neck or an upper portion of a container10. For instance, a container holder20′ may be configured to, instead of or in addition to engaging a base portion, engage a top of a neck and/or a flange portion of the container. A container holder20′ may, if desired, be configured to deliver the held or retained container to or into a lower holder (such as a cup-type holder, e.g., holder20). As generally illustrated inFIG. 4, a container (e.g., container holder20′) may be connected to a servo motor (e.g., servo motor22) and, for some embodiments, may further be configured to deliver a downward force on the container. As generally illustrated inFIG. 4, a servo motor may be associated with the rotation of an individual container about an axis, and a separate (commonly more powerful) servo motor24may be associated with a rotary wheel26, which in turn is associated with the collective movement of a number of container holders (and hence containers).

In another embodiment, for example and without limitation, a container holder20′ may hold or retain a neck or an upper portion of a container. The container holder20′ may be configured to engage a top of a neck and/or a flange portion of the container, the container holder20′ may be connected to a servo, and no lower container holder (such as a container holder20) may be required. In embodiments the container holder or holders, e.g., illustrated container holders20and/or20′ (which when more than one holder is employed in connection with a single container may be collectively referred to as a single “container holder”), may be configured to rotate 90 degrees or more. Further, embodiments of the system may employ a constant velocity or an indexed process. To print up to 360 degrees around the circumference of a container, the container may be positioned in front of an associated print head, and rotated up to 360 degrees in front of the print head.

As generally illustrated inFIG. 1, a rotary system5may include a plurality of container holders20. Further, the plurality of container holders20may be configured to follow a curved or rotary path, and the container holders20may be further configured to rotate individual containers received within the container holder20about an axis. For embodiments, the axis about which the container holder20rotates may substantially correlate to a central longitudinal axis of an individual container10. For other embodiments, the axis about which the container is rotated may instead correspond to the rotational axis of the container holder, which may not coincide with the axis of the container provided therein.

Rotary systems such as described herein may provide for direct printing (e.g., direct digital printing) on curved surfaces of containers at relatively high production speeds. However, alternative embodiments for a rotary system may be incorporated or employed. For example, and without limitation, a system may be configured so that containers move along a substantially linear path, and individual containers are rotated in front of one or more print heads/stations (e.g., about a central container axis) so as to provide or maintain a substantially constant distance or radius between the print head and the surface to be printed. In another embodiment of a system, a container path—at least in front of one or more print heads—may be configured with a radius or curved portion to facilitate providing a substantially constant distance between the print head and the print area on the container. It is noted that the print heads associated with the various disclosed embodiments may optionally be movable. Such movability can facilitate providing or maintaining a substantially constant distance (e.g., offset distance) between a print head and the print area or surface to be printed. Moreover, the ability to provide or maintain such a distance can be used in connection with non-round containers or containers that have surface portions with non-constant radii.

As generally shown inFIG. 1, an embodiment of the rotary system5may include a device configured to fix or determine an initial position and orientation of an individual container (e.g., an orientation lug registration device and/or a vision or scanning device30), one or more pre-treatments devices40, a supply mechanism (e.g., a supply conveyor50), a receiving mechanism (e.g., a receiving conveyor60), a supply wheel70(which may be associated with the supply mechanism), an exit wheel80(which may be associated with the receiving mechanism), a primary wheel90, a plurality of print heads (or print stations)100, and one or more curing devices (or curing stations)110. In embodiments, it may be desirable to configure the plurality of print heads100so that their print path is substantially tangent to the path of the surface of the container to be printed. The line inFIG. 1designated120generally represents the midpoint (180 degree point) of the rotary system5.

It is additionally noted that with respect to ink delivery, where rotary movement is involved, the system may incorporate a compensation to address gravity and/or centrifugal forces (which may, for example, be a function of wheel speed). Force algorithms or curves may be used to adjust print head output to compensate for rotational speed and to prevent unintended discharge or drool from the print heads when spinning. For example, a force algorithm or curve may be employed to adjust meniscus pressure to compensate for rotational speed and to maintain a desired or acceptable meniscus at a print nozzle.

As mentioned, for some embodiments, the device configured to fix or determine an initial position and orientation of an individual container comprises a vision or scanning device30. The device30may be configured to determine the position and/or orientation of each individual container10. In embodiments, the vision or scanning device30may be positioned to “look” downward at the container. For example, without limitation, the vision or scanning system may look downward (e.g., through the opening of the container) and pick out a landmark or feature of the container (e.g., which may be a formation provided in the base portion of the container). In addition, or alternatively, particularly with containers that are retained by an upper container holder (e.g., container holder20′), a vision or scanning system may be provided that “looks” upward at the container. The vision or scanning device may comprise various conventional systems as are known in the art. In embodiments, the vision or scanning device30may determine the position and/or orientation of the container as it enters the rotary system5. For example, a container10may exit a supply wheel70and can be received within a container holder20associated with the primary wheel90of the rotary system5.

As generally illustrated, a pre-treatment device40may provide a form of heat treatment to the containers. Such heating may be accomplished using known techniques including, without limitation, flame, forced air plasma, or corona heating/treatment processes. The curing device/station110may comprise a number of forms of curing devices including, for example, ultraviolet (UV) lamps (which may include LED components), radiation curing devices, and other known curing devices.

FIG. 3is a side elevation view of a rotary system5of the type generally illustrated inFIG. 1. As generally illustrated, a container10may held or retained at a lower end of the container by a container holder20. The container10may also be handled or secured at or about a container upper end, e.g., about an opening and/or via a container neck flange, by another container holder20′. Together container holder20and container holder20′ comprising a collective “container holder” with respect to the container10. In an embodiment, each container holder (for example,20and/or20′ as generally illustrated inFIG. 3) may be configured to rotate about a container holder axis such that the container holder can rotate to a desired extent. By way of example and without limitation, one or more container holders may be individually rotated by a servo mechanism such that the container holder, and consequently the held container, may be rotated to various desired degrees, up to and including 360 degrees or more. Further, by employing information obtained from the vision or scanning device, the orientation of each container10may be registered and controlled/adjusted in connection with the orientation of the container holder20. For example, each container may be initially registered and, if appropriate, turned to a desired starting orientation for a given position in the system. By rotating the container holder20, a desired portion of the surface of the container10may then be controllably presented to one or more devices (e.g., printing or curing) provided about the path of rotational movement of the primary wheel90.

An example of a rotary system5generally illustrating features of the disclosure, including an indexing system/process, is shown inFIG. 5. As illustrated, the rotary system5may include a primary wheel90, an input/supply wheel130, a plurality of holders20, a pre-treatment device40, a plurality of print heads100configured to print directly on the containers10, a plurality of curing devices110, and an exit/output wheel140. As indicated, the primary wheel can be configured to rotate in a clockwise direction, while the input/supply wheel130and the exit/output wheel can be configured to rotate in an opposing (e.g., counter-clockwise) rotational direction. As generally illustrated, the container holders20may be configured to rotate individual containers10. In the illustrated embodiment, the container holders20are configured to rotate an individual container in a counterclockwise direction. A pre-treatment device40, a plurality of print heads100, and/or one or more curing devices110may be provided about the periphery of the primary wheel90. For embodiments, the print heads may be substantially stationary with respect to the primary wheel90. Although, for some embodiments a pre-treatment device40, a plurality of print heads100, and/or one or more curing devices110may be configured for movement, for example and without limitation, toward and away from the primary wheel90. A device for fixing or determining an initial position and orientation of an individual container is generally shown as30. In an embodiment of the illustrated system5, the primary wheel can be configured for indexed rotational movement. For example, without limitation, containers may be brought to the primary wheel, and holders associated therewith, by an input/supply wheel130. The container may be accepted by a holder and moved to index positions provided about the wheel and associated with various operations, e.g., pre-treatment, printing, and curing. At the site of each operation, the container/container holder may rotate so as to present a desired amount of rotational surface of the container to the operation. When the operation is completed, the rotation of the container can cease and the primary wheel can index to the next position. With some embodiments the printing and/or curing operations only occur while the rotation of the primary wheel is ceased and is properly positioned in front of the applicable operation.

Another example of an indexed system/process is generally illustrated inFIG. 6. As generally shown, the primary wheel90may comprise an inner wheel150and an outer wheel160. The container holders20, which may rotate about an axis, can be provided in connection with the outer wheel160, while other operations (pre-treatment, printing, curing) may be provided in connection with the inner wheel150. For example, with such a configuration, an inner wheel150with print heads100a-100ecould print and index back as the outer wheel160with the container holders (and the containers) turns. For instance, without limitation, in an embodiment, a first print head100amay print a base coat (e.g., a white or clear base coat), the base coat may be cured110a,and the container may be moved by a plurality of print heads printing colors (e.g., cyan100b,magenta100c,yellow100d,black100e), the one or more colors may then be individually or collectively cured110b,and the process may be repeated with a subsequent container. As with the other embodiments, a device for fixing or determining an initial position and orientation of an individual container may be included with the system5. The outer wheel160can be configured to generally rotate in a given rotational direction (e.g., counter-clockwise), and the inner wheel150can be configured to rotate both in the same direction as the outer wheel160(e.g., counter-clockwise), and “backwards” with respect to the outer wheel160(e.g., clockwise).

In an embodiment of the rotary system5such as illustrated inFIG. 6, the outer wheel160may be configured to rotate at a constant rotational velocity or speed, while the rotational velocity or speed and rotational direction of the inner wheel150can be changed or varied. For instance, when the inner and outer wheels are moved in the same rotational direction at substantially the same rotational velocity or speed (i.e., there is a rotational match or alignment), an operation can occur with respect to a container. That is, the container holder can present (i.e., rotate) the container for the applicable operation. Once the respective operation is completed, the speed and/or direction of the inner wheel150can be changed. For instance, a container can be loaded and a base coat can be printed thereon (while the direction and rotational speed of the inner and outer wheels substantially match). After the operation (e.g., printing of a base coat) is completed, the inner wheel150can rotate or index “backwards” to another/related operation (e.g., curing of the base coat), while the next bottle in succession is loaded and may undergo an operation just experienced by the preceding container (e.g., printing of a base coat). With such a system and process the inner wheel150can index back while the larger outer wheel160turns.

An embodiment of a method for printing on plastic containers is next generally described. A plurality of containers10are introduced to a rotary system5. In an embodiment, the containers10may enter via a handling device such as a supply wheel70. Each individual container10may be held or secured by a container holder20. In an embodiment, a vision or scanning device30may “read” the container10and, using a feature or landmark associated with the container10, and may register the position and/or orientation of the container with respect to the container holder20and/or the rotary system5. In other embodiments, the container may be physically oriented, such as by an orientation lug or other means practiced in the field. The container holder20may then be registered or synchronized, and/or rotationally controlled to position the container in a desired position and/or orientation, e.g., a known or registered starting position. The container10will generally have a first side (e.g., side A) that faces radially outwardly (i.e., away from the central rotary position15). For some applications, the container (e.g., side A) may initially be exposed to a pre-treatment (e.g., a pre-treating process). The primary wheel90may then rotate and the container may be exposed to a first print head/station100, which may apply a first print (e.g., a first ink or first color), which may comprise a base coat. In embodiments such a base coat may be clear or white. If desired, the primary wheel90may further rotate to or provide alignment with a curing device/station110and the first print may be cured. The primary wheel90may then rotate to or align with a second print head/station and, if desired, a second print (e.g., a second ink or second color) may be applied (also generally to side A). The second print may then be cured in a manner as previously mentioned. The foregoing printing (or print-cure) steps may be repeated a number of times. At some point in the path of the primary wheel90, the container holder20may be rotated (e.g., 180 degrees), which may expose a different “face” of the container (e.g., opposing side B), and the next successive rotary stations may repeat a process of printing (or print-cure). After the desired printing (or print-cure) steps have been accomplished, the container10may be directed from the system5, for example, via an exit wheel80.

The method and aforementioned system apparatus may be configured so as to be substantially customizable. For instance, the system5may be used with containers of different sizes and/or shapes. The system5may be programmed such that the rotations of the primary wheel and the container holders are coordinated/adapted for various sets or even individual containers, and particularly such that certain print portions or print “faces” of the container are provided substantially at tangents with respect to various stations provided in connection with the system. Among other things, the system5can account for or correlate the radii/path of the primary wheel90and the radii/spin of the containers10to optimize the time (in print zone) and/or positioning of the container surface for printing with respect to the associated stations. It is anticipated that embodiments of the system5can be configured to produce printed plastic articles (e.g., plastic containers) or any other generally cylindrical objects at rates equal to or in excess of720containers per minute. Moreover, in some embodiment, the printed articles may, instead or in addition to plastic, comprise glass, ceramic, or various metals.

In alternate embodiments of the rotary system5, one or more print heads may be movable (e.g., radially inwardly-outwardly and/or vertically (up-down). Such print heads may be desirably articulated during the printing process to maintain a constant distance and perpendicularity from the container surface. Further, a plurality of sensors may be used to measure the curvature of the non-planar surface and/or control the articulation of the plurality of print heads to maintain the constant distance and perpendicularity from the non-planar surface.

Although numerous embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.