FIELD OF THE DISCLOSURE

[0001] The present disclosure generally relates to the field of printing. In particular, the present disclosure is directed to independent print datum detection.

BACKGROUND

[0002] Current rotary digital printing solutions on the market today have either (1 ) low throughput, low cost, low fixture setup time, or (2) high throughput, high cost, high fixture setup time. The market does not currently have a medium cost, high throughput, low fixture setup time solution. The challenge forcing these two market options is that you must transport your complex fixture back to the starting position of the first print head while maintaining precision motion monitoring and control through the entire print zone. Currently, a way to achieve higher throughput is to maintain a singular rotary transport mechanism which can add substantial expense. One example of a machine that offers lower fixture set up time is a single piece rotary print. Both prior art approaches utilize a single print encoder to manage color-to-color registration between print stations. Rotary printing with multiple print stations requires high precision, for example, a circumferential tolerance of approximately +/- .0013" for a 360 DPI inkjet head to avoid visual defects. Current approaches achieve the required tolerance by constantly tracking the circumferential speed and position of all fixtures through a single drive and a single encoder.

SUMMARY

[0003] According to an aspect of the present disclosure there is provided a rotary digital printing system, comprising: a print zone, which comprises a plurality of independent print stations, each station comprising a respective print head, curing system, and read head; a plurality of fixtures, each fixture being configured to support an item that is to receive printed information, and comprising an encoder ring that can be read by a given print station's read head to determine a circumferential position and rotational speed of the fixture in question; a rotational drive for rotating each fixture positioned in a print station such that the surface of the item support member and an item disposed thereon is rotated past the print head and curing system for printing and curing; and a conveyance module for transporting the fixtures to said print stations. The system is configured so as to convey, using said conveyance module, the plurality of fixtures through the print zone, stopping at one or more of the print stations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] For the purpose of illustrating the disclosure, the drawings show aspects of one or more embodiments of the disclosure. However, it should be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a side view of a rotary digital printing system;

FIG. 2 is a perspective view of the system of FIG. 1 ;

FIG. 3 is another perspective view of the system of FIGS. 1 and 2;

FIG. 4 is a perspective view of a conveyance module;

FIG. 5 is a perspective view of a fixture;

FIG. 6 is a perspective view of a print head module;

FIG. 7 is a perspective view of a curing module;

FIG. 8 is a perspective view of a rotational drive;

FIG. 9 is another perspective view of the system of FIGS. 1 and 2;

FIG. 10 is a front view of the system of FIGS. 1 , 2, and 9; and

FIG. 1 1 shows the directions in which the curing and printing modules can move.

DETAILED DESCRIPTION

[0005] FIGS. 1 -1 1 illustrate an example embodiment of a rotary digital printing system 1 with independent and intermittent fixture monitoring. Referring to FIGS. 1 and 2, the example system 1 includes a print zone that includes six independent print stations 100(a)- (f), where each station 100(a)-(f) includes a print head 1 10, a read head 120, and, optionally, a curing system 130. A plurality of fixtures 200 (see also FIG. 5) can be conveyed through the print zone, stopping at one or more of the print stations 100(a)-(f). Each fixture 200 includes an encoder ring 230 (FIG. 1 ) that can be read by a given print station's 100(a)-(f) read head 120 for determining, e.g., a circumferential position and rotational speed of a fixture 200. The system 1 also includes a rotational drive 400 for rotating each fixture 200 positioned in a print station 100(a)-(f).

[0006] Each fixture 200 may support an item (not illustrated) for receiving printed information. In the illustrated example, each fixture 200 includes a frusto-conical item support member 210 for supporting an item that will receive a printed image. As discussed below, in other examples, alternatively shaped item support members can be used. During operation, a fixture 200 can be positioned at a print station 100(a)-(f) between one of the print heads 1 10 and curing systems 130 (FIG. 1 ). The rotational drive 400 rotates the fixture 200 such that the surface of the item support member 210 and an item disposed thereon is rotated past the print head 1 10 and (where present) the curing system 130 for printing and curing.

[0007] In the illustrated example, a rotational speed and rotational position of each fixture 200 located in a print station 100(a)-(f) is independently monitored by a corresponding respective independent read head 120 (FIG. 1 ). Each read head 120 reads the encoder ring 230 of a corresponding fixture 200 to determine a circumferential position and rotational speed of a given fixture 200. The read head 120 is in communication with a corresponding print head 1 10 for a given print station 100(a)-(f) for communicating a position and speed signal. A print head 1 10 may use the read head signals for determining a timing and speed for printing information on an item supported by the fixture 200. In one example, the print heads 1 10(a)-(f) are independently controlled by a corresponding print head controller (not illustrated). The print head controller may control a printing operation of the print head 1 10 based on signals received from the independent read head 120. Each read head 120 and corresponding encoder ring 230 may include a circumferential trigger for determining a rotational position of a fixture 200. For example, the read head 120 may identify a circumferential datum of the fixture 200. In one example, a z-pulse encoder may be used. The print head controller may use the circumferential trigger to control the print head 1 10. For example, each of the print heads 1 10 may use the circumferential trigger to ensure the printing of each print head 1 10 is precisely aligned on the surface of an item. For example, if each print station 100(a)-(f) includes one of cyan (C), magenta (M), yellow (Y), and black (K) inks for printing an image that includes a mixture of two or more of CMYK, each station 100(a)-(f) may use the circumferential trigger information to ensure each of the C, M, Y, and K images are precisely aligned on the surface of the item. In other examples, any of a variety of sensors may be used for independently monitoring a circumferential position of each fixture 200. The illustrated system, therefore, provides for intermittent fixture circumferential position and speed monitoring as a fixture 200 is transported through a plurality of print stations 100(a)-(f). This is in contrast to prior art systems, which require constant tracking of the circumferential speed through a single drive and a single encoder for a full transport of a fixture through all printing stations. Such intermittent and independent monitoring makes each print station modulated and allows for a variety of print head and fixture combinations. For example, the print stations 100(a)-(f) can operate independent of each other such that a color or station can be added without impacting the rest of the machine, making the system easily scalable.

[0008] FIG. 4 illustrates a conveyance module 300 of the system 1 of FIG. 1 that transports the fixtures 200 to each of the print stations 100(a)-(f). In the illustrated example, the conveyance module 300 is a linear motor system. In one example, a MagneMotion® linear motor system from Rockwell Automation, Inc. may be used. In other examples, any of a variety of other conveyance systems may be used. In the illustrated example, the conveyance module 300 provides linear motion by moving the fixtures 200 through the print zone, but does not provide rotational motion, the rotational motion being provided by the rotational drive 400 (FIGS. 1 and 8). Thus, in the illustrated example, linear and rotational drives are decoupled, which can provide a variety of benefits including non-traditional floor plan layouts outside of circular (rotary) and oval or over under, ability to add on to an existing manufacturing line, and providing secondary operations such as assembly, inspection, or packaging. In one example, a location of the fixtures 200 on the conveyance module 300 can be determined with pneumatically engaged conical pin registration to precicely locate the fixtures 200 at each printing station 100(a)-(f). In other examples, a position indicator associated with the linear motor system may be used to control a position of each fixture 200 in each printing station 100(a)-(f). [0009] FIG. 5 illustrates a fixture 200 for supporting an item for receiving printed information, such as product packaging. As will be appreciated by a person having ordinary skill in the art, although the item support member 210 is frusto-conical, any of a variety of other shapes and configurations may be used, which can be dictated by the specific size and shape of the item requiring printed information. The item support member 210 may be coupled to a shaft 220 that includes an encoder ring 230, and the shaft 210 may be rotationally coupled to a base 240. The shaft 220 can be configured to be releasably coupled to the rotational drive 400, such that the fixture 200 can be decoupled from the rotational drive 400 during linear movement by the conveyance module 300 and coupled to the rotational drive 400 for rotational movement when located in a printing station 100(a)-(f). In one example, the rotational drive 400 may include a friction drive belt system with no positive mechanical engagement on the fixture 200. In some examples, a pneumatically actuated linear slide may also be included on the belt system for increasing the frictional coupling between the belt 410 and the fixture 200.

[0010] FIG. 6 illustrates the print head module 10. In the illustrated example, the module 10 is configured for six colors, one printed by each print head 1 10 at each station 100(a)-(f). The module 10 contains all subsystems to support full printing. Referring to FIG. 1 1 , the module 10 can move according to the following servo axis: rotation R2; vertical travel Y'2; and infeed X2. These degrees of freedom give the customer the ability to do either stitch or helix printing on tapered or cylindrical objects. In the illustrated example, each print head 1 10 includes an independent controller for independently controlling printing at the corresponding print head 1 10 based on the position and speed information provided by the independent read heads 120.

[0011] FIG. 7 illustrates the curing module 20. In the illustrated example, the curing module 20 is an ultraviolet (UV) curing module, which uses UV light to cure UV-curable ink, as is known in the art. In other examples, any other kind of curing technique may be used, such as hot air. Referring to FIG. 1 1 , the curing module 20 can move according to the following servo axis: rotation R1 ; vertical travel ΥΊ ; and infeed X1 ; for allowing the curing module 20 to move down the side of a conical item at the same rate, but opposite angle, of the print head 1 10. [0012] FIG. 8 shows the rotational drive 400 for rotating each of the fixtures. The illustrated example is a belt drive, and may use any kind of belt 410, e.g., round or flat. The rotational drive is configured to rotate the fixtures located in the printing zone over a large speed range via a servo controlled drive motor. In other examples the system may include separate rotational drives for driving one or more fixtures located in print stations. Also, rather than a belt drive, any of a variety of rotational drive systems may be used, such as , such as independent friction wheels for driving each fixture.

[0013] FIGS. 9 and 10 show additional views of the assembled system.

[0014] Some benefits provided by systems made in accordance with the present disclosure include the ability to load and unload fixtures, whether manually or with robotics; the ability to pretreat with a flame unit or corona treatment; and the ability to provide an inspection station, where a fixture can be removed from the conveyance module without stopping operation of the system. Additional benefits also include providing a printing system for a high mixture of product types and medium volume production; providing redundancy in the system, for example, if one fixture, transport, print stations, or encoder is disabled for maintenance, the system can still be operational; allowance for external operations to be conducted in process, for example, inspection, pretreatment, post packaging, etc. without disrupting the flow of work; and the system can be scaled up or down with minimal design changes to run one or more fixtures as desired and based upon production needs. [0015] The foregoing has been a detailed description of illustrative embodiments of the disclosure. It is noted that in the present specification and claims appended hereto, conjunctive language such as is used in the phrases "at least one of X, Y and Z" and "one or more of X, Y, and Z," unless specifically stated or indicated otherwise, shall be taken to mean that each item in the conjunctive list can be present in any number exclusive of every other item in the list or in any number in combination with any or all other item(s) in the conjunctive list, each of which may also be present in any number. Applying this general rule, the conjunctive phrases in the foregoing examples in which the conjunctive list consists of X, Y, and Z shall each encompass: one or more of X; one or more of Y; one or more of Z; one or more of X and one or more of Y; one or more of Y and one or more of Z; one or more of X and one or more of Z; and one or more of X, one or more of Y and one or more of Z.

[0016] Various modifications and additions can be made without departing from the spirit and scope of this disclosure. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present disclosure. Additionally, although particular methods herein may be illustrated and/or described as being performed in a specific order, the ordering is highly variable within ordinary skill to achieve aspects of the present disclosure. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this disclosure.

[0017] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present disclosure.