Abstract
A system is disclosed that provides a compact printing system for applying images on the exterior of a clear or semi-transparent 3-dimensional object, such as for example a clear container like a wine bottle. The printing system includes a shuttle system for transporting a grouped parallel series of blank 3D media simultaneously into a printer portion of the system for parallel printing of media. The printer includes a series of printing tunnels that control a novel arrangement of print heads, pinning lamps, and a final cure lamp that minimizes or eliminates the chances for stray UV light to potentially impinge upon and foul inkjet printing heads used to express ink onto the surface of the 3D media. The arrangement allows for a higher degree of throughput of 3D media while avoiding the prior problems of the fouling of printheads during the printing of images on transparent or translucent media.
Claims
1. A printer for printing on the surface of three-dimensional transparent media, comprising: a. a printing carriage for holding at least one piece of three-dimensional transparent object media, said carriage movable from a loading position to a printing position, wherein said carriage includes means for controllably rotating each said at least one piece of media during printing on said media surface; b. a vertically movable support platform, said platform including printing means for expressing jetted ink onto the surface of said media, a pinning lamp positioned adjacent to said rotating media, and a separate final curing lamp, wherein said platform is movable such that said inkjet printing means, said pinning lamp, and said curing lamp are positioned into close proximity to said media responsive to the size of said media; and, c. wherein said pinning lamp is positioned to create a beam field that points away from said inkjet printing means while impinging said beam field on the surface of said transparent media at a location of between 180 and 360 degrees radially around the axis of rotation of said media and relative to the direction of rotation of said media.
2. A printer as recited in claim 1, wherein said beam field of said pinning lamp includes an external edge and an internal edge relative to the central axis of rotation of said media, and wherein said external edge forms a point of tangency along the surface of said media.
3. A printer as recited in claim 2, wherein the radial location of said point of tangency comprises a range of between plus or minus 45 degrees from 270 degrees radially around the axis of rotation of said media and relative to the direction of rotation of said media.
4. A printer as recited in claim 1, wherein said pinning lamp is tiltable relative to said printing means such that said pinning lamp produces a beam field adjustable to cover a user selectable surface area of said media.
5. A printer as recited in claim 4, wherein said pinning lamp is movable proximally and distally relative to said printing means such that said pinning lamp produces a beam field adjustable to cover a user selectable surface area of said media.
6. A printer as recited in claim 5, further comprising a plurality of slots on said printing carriage for holding a plurality of media in parallel relation thereof, and wherein when said printing carriage is moved into said printing position said printer is configured to print on each piece of media simultaneously.
7. A printer as recited in claim 6, wherein said movable support platform comprises: a. a gantry supported by said printer; b. a support assembly depending downward from said gantry and movable up and down relative to said media when said carriage is moved into said printing position; and, c. wherein said support assembly holds at least one printing means, one pinning lamp, and one final curing lamp in proximal relation to the surface of each said at least one piece of media when said printing carriage is moved into said printing position.
8. A printer as recited in claim 7, wherein said movable support platform includes means for electronically adjusting the height of said support assembly relative to said at least one piece of media.
9. A printer as recited in claim 7, wherein said movable support platform includes means for electronically adjusting the height of said support assembly relative to said at least one piece of media and electronically adjusting the distance of said pinning lamp from said printing means.
10. A printer as recited in claim 1, wherein said movable support platform comprises: a. a gantry supported by said printer; b. a support assembly depending downward from said gantry and movable up and down relative to said media when said carriage is moved into said printing position; and, c. wherein said support assembly holds at least one said printing means, one said pinning lamp, and one said final curing lamp in proximal relation to the surface of each said at least one piece of media when said printing carriage is moved into said printing position.
11. A printer as recited in claim 10, wherein said pinning lamp is tiltable relative to said support assembly to form an angle of between 70 and 120 degrees relative to the ink expression direction of said printing means.
12. A printer as recited in claim 1, further comprising a material handler, said material handler including: a. a loading shuttle for moving media toward said printing carriage; b. a pneumatic robot having at least one gripper arm for moving said media from said loading shuttle onto said printing carriage; c. an off-loading area; d. wherein said pneumatic robot is configured to move decorated media from said printing shuttle to said off-loading area after printing thereof.
13. A printer for applying ink to create images on the surface of three-dimensional transparent media, comprising: a. holding means for holding a piece of media at its ends and rotating said media during the application of ink onto the surface of said media; b. printing means for applying ink to the surface of said media during rotation thereof; c. a curing lamp for curing ink expressed onto the surface of said media; d. a pinning lamp for partially curing ink expressed onto the surface of said media; e. wherein said printing means, said curing lamp and said pinning lamp are movable to be positioned proximal to the surface of said media during printing; and, f. wherein said pinning lamp is positioned to create a beam field that points away from said printing means while impinging said beam field on the surface of said media at a location of between 180 and 360 degrees radially around the axis of rotation of said media and relative to the direction of rotation of said media.
14. A printer as recited in claim 13, wherein said beam field of said pinning lamp includes an external edge and an internal edge relative to the central axis of rotation of said media, and wherein said external edge forms a point of tangency along the surface of said media, and wherein the radial location of said point of tangency comprises a range of between plus or minus 45 degrees from 270 degrees radially around the axis of rotation of said media and relative to the direction of rotation of said media.
15. A printer as recited in claim 14, wherein said pinning lamp is tiltable and laterally movable relative to said printing means such that said pinning lamp produces a beam field adjustable to cover a user selectable surface area of said media.
16. A printer as recited in claim 13, further comprising a plurality of slots within said holding means for holding a plurality of media in parallel relation thereof, and wherein said holding means is movable from a loading position to a printing position, and wherein when said holding means is moved into said printing position said printer is configured to print on each said piece of media simultaneously.
17. A printer as recited in claim 16, wherein said movable support platform comprises: a. a gantry supported by said printer; b. a support assembly depending downward from said gantry and movable up and down relative to each said piece of media; and, c. wherein said support assembly holds at least one said printing means, one said pinning lamp, and one said final curing lamp in proximal relation to the surface of each said piece of media when said printing carriage is moved into said printing position.
18. A printer as recited in claim 13, wherein said movable support platform includes means for electronically adjusting the height of said support assembly relative to each said piece of media and electronically adjusting the lateral distance of said pinning lamp from said printing means.
19. A printer as recited in claim 13, wherein said beam field of said pinning lamp includes an external edge and an internal edge relative to the central axis of rotation of said media, and wherein said external edge forms a point of tangency along the surface of said media, and wherein the radial location of said point of tangency comprises a range of between plus or minus 45 degrees from 270 degrees radially around the axis of rotation of said media and relative to the direction of rotation of said media.
20. A printer for applying images onto the surface of three-dimensional transparent media, comprising: a. holding means for holding said media at its ends and rotating said media during the application of ink onto the surface of said media; b. printing means for applying ink to the surface of said media during rotation thereof; c. a curing lamp for curing ink expressed onto the surface of said media; d. a pinning lamp for partially curing ink expressed onto the surface of said media; e. wherein said printing means, said curing lamp and said pinning lamp are movable to be positioned proximal to the surface of said media during printing; and, f. wherein said pinning lamp is positioned to create a beam field that points away from said printing means while impinging said beam field on the surface of said media at a location that permits full wetting of said ink on the surface of said media prior to hardening into a gel state.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A compact 3D object decorating machine incorporating the features of the various inventions is depicted in the attached drawings which form a portion of the disclosure and wherein:
(2) FIG. 1 is a front perspective view of the 3D object decorating system showing the major elements of the machine;
(3) FIG. 2 is a rear perspective view of the decorating system showing the arrangement of the printing portion of the decorating system in relation to the material handling portion of the machine;
(4) FIG. 3 is a rear perspective view of the material handling portion of the machine;
(5) FIG. 3A is a perspective view of the pneumatic robot handler within the handling portion of the machine in isolation;
(6) FIG. 4 is a front perspective view of the printing portion of the decorating machine;
(7) FIG. 5 is an expanded front perspective view of the printing portion of the decorating machine;
(8) FIG. 6 is a side elevational view of the printing portion of the decorating machine;
(9) FIG. 7A is an expanded right perspective view of the printing portion of the decorating machine showing the arrangement of the printheads and UV emitters;
(10) FIG. 7B is an expanded left perspective view of the printing portion of the decorating machine showing the arrangement of the printheads and UV emitters;
(11) FIG. 7C is an expanded front, elevational view of the printing portion of the decorating machine showing the arrangement of the printing carriage and printing tunnels;
(12) FIG. 7D is a perspective view of the printing portion of the decorating machine showing the lifting gantry and printer support assembly in isolation;
(13) FIG. 7E is a top perspective view of the printing support assembly of FIG. 7D shown in isolation;
(14) FIG. 7F is front perspective view of the printing support assembly of FIG. 7D showing the lateral and angular movement adjustment means;
(15) FIG. 8 is a diagrammatic view of a final cure step in the printing process of the decorating machine;
(16) FIG. 9 is a further diagrammatic view of a portion of the final cure steps during printing;
(17) FIG. 10 is a further diagrammatic view of a portion of the final cure steps providing an option to minimize UV radiation scattering within the printing portion of the decorating machine;
(18) FIG. 11A is diagrammatic perspective view of the arrangement of a bank of ink printing heads in relation to an adjustable UV pinning lamp above a rotating piece of media;
(19) FIG. 11B is a diagrammatic elevational view of the arrangement of a bank of inkjet printing heads in relation to an adjustable UV pinning lamp above a rotating piece of media;
(20) FIG. 12A is a diagrammatic view of the arrangement of a bank of inkjet printing heads in relation to an adjustable UV pinning lamp above a rotating piece of media showing a substantially wedge shaped zone of UV illumination;
(21) FIG. 12B is a view showing various positional arrangements of the pinning UV lamp in relation to the media and the inkjet printing heads, and the effect of such positions to create zones of UV illumination;
(22) FIG. 13A is a diagrammatic view of a final cure UV lamp above a rotating piece of media as it moves under the UV lamp;
(23) FIG. 13B is another a diagrammatic view of a final cure UV lamp above a rotating piece of media showing curing lamp intensity variations during a final cure step;
(24) FIG. 14 is a flow diagram of using a power scale factor calculation for a final cure step in the disclosed decorating machine;
(25) FIG. 15 is a flow diagram of a UV pinning lamp configuration process for pinning an image onto the exterior of a 3D object in the disclosed system; and,
(26) FIG. 16 is a flow diagram of a process for minimizing UV radiation reflections during final curing of an image on the exterior of a 3D object in the disclosed decorating system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(27) Referring to the drawings for a better understanding of the function and structure of the invention, FIGS. 1 and 2 show perspective views of the decorating machine 10 showing the primary external components of the system. Machine 10 includes a material handling or “feed” system portion 11 and a printer system portion 12 mated to one another in a “T” configuration. An operator is positioned adjacent to the feed system 11 at a convenient location 14 from which they may load undecorated media 20 onto a loading shuttle 19 positioned in a loading area 13 and adjust the operation of the system 10 through a human machine interface (HMI) via a display terminal (not shown) held by support 24. The shuttle 19 is supported by a pair of rails 22 and includes media support brackets 21 that are sized to support a variety of sizes of media 20 in a horizontal orientation. For the purposes of the present system, the targeted type of undecorated media is a transparent (i.e. visually clear) or semi-transparent (e.g. translucent, frosted or colored glass containers) 3D object. Each portion (11,12) of the machine 10 includes suitable support frames 17, external panels 16, and support rollers 18 through which each subsystem is supported.
(28) Once loaded with undecorated media 20, shuttle 19 may be moved by the operator from the loading area 13 to a pickup area 25 along rails 22. Pickup area 25 is positioned such that a pneumatic robot 26 may grip and raise each undecorated media piece above the shuttle 19 and deliver it onto a printing carriage 28 for conveyance into printing portion 12, or for removal of decorated media 30 from printing carriage 28 and delivery into product removal area 35. The removal area may include tilted supports 34 as shown to facilitate removal of decorated product from the machine 10 by an operator.
(29) FIG. 3 shows a closer view of the media handling portion of the system 10 with the printer portion 12 removed. As may be seen, pneumatic robot 26 can move either left or right to deposit media from the loading pickup area 25 to the printer carriage 28 or from the printer carriage 28 to the product removal area 35. Printer carriage 28 is supported by a portion of printer 12 that is positioned or mated with portion 11 within a vacant section 40 of material handler 11. As more easily seen in FIG. 3A, pneumatic robot 26 includes a gantry subassembly 31 having a lower gripper assembly 32 depending downward via vertical supports as shown. Gripper assembly 32 includes at least two sets of gripping or grasping mandibles 27(a,b) that are sized to open and close around 3D objects, such as a container like a wine bottle and the like, which are generally referred to herein as “media.” A pair of rails 33 are held by gantry 31 to allow for the slidable movement of gripper assembly 32 to slide along a media loading path 29a or along a media unloading path 29b. The arrangement allows for the rapid simultaneous movement of two sets of media to and from loading and unloading areas 13 and 35.
(30) Referring now to FIGS. 4 and 5, it may be seen that printer carriage 28 is supported by a pair of rails 41 on a lower enclosure 38 that is sized to fit into space 40 of material handler 11. When enclosure is mated with handler 11, the rails 41 permit printer carriage 28 to traverse from within the handler 11 and into a series of parallel printing tunnels 44 along path 43 and formed within printer section 12. Printing occurs on each piece of undecorated media 20 within these tunnels 44. The disclosed embodiment shows 4 tunnels, but the inventors foresee that the number of tunnels may be enlarged to increase material printing throughput to the extent that the material handling section is designed to move material across an increased number of tunnels using an enlarged gripping set.
(31) Printer 12 includes a lower front enclosure section 38 that is connected to a taller section 39 that holds various printer support subsystems. Lower enclosure section 38 houses a standard personal computer or PC 50 that is connected through cables with display terminal (not shown) held by a display terminal support 24 for control of the system 10 via an HMI by an operator. A suitable PC for system 10 is a 2.9 GHz Intel Core i7, with 16 GB RAM and an Intel UHD graphics processor 630, and running Windows 10 (HP part No. 2X3K4UT #ABA). Section 39 includes an ink delivery subsystem 45 connected and controlled by the personal computer 50 for delivering ink to a series of inkj et printer heads within printer image deposition and curing area 55. A suitable print engine and ink recirculation system for system 10 is the available from INX International Ink Co. under part Nos. 99-14080 (Head Drive Mother Board) and 99-14081 (Gen 4 Printhead Control Board) as part of their JetINX™ printhead drive electronics component and ink delivery system offerings. As will be further discussed, tunnels 44 are sized to allow the passage of media 20 underneath section 55 and include a plurality of inkjet heads and UV lamps that are positioned within close proximity to the surface of each piece of media 20 once positioned within each tunnel 44. Suitable printheads for printer portion 12 are the Gen 4 Print Heads offered by Ricoh Company, Ltd. under part No. N220792N. Suitable UV lamps for both final curing and ink pinning are available from Phoseon Technology under its FireEdge FE400 LED curing line of products (Part No. FE400 80X10 8W).
(32) FIG. 6 shows the tunnel area 44 above which a printhead and cure lamp support assembly 60, including a support gantry 56, are positioned to allow for adjustment of the relative positions of the printheads and cure lamps so that various sizes of media may be accommodated by the printer 12.
(33) Referring to FIGS. 7A-7E it may be seen the tiltable arrangement of the pinning UV lamps 58 in relation to the printheads 57 and final cure UV lamps 59. Gantry 56 may be raised and lowed in response to operator inputs that set heights in relation to each media size, thereby raising and lowering the printheads 57 and final cure lamps 59 which are affixed and supported by support assembly 60. Pinning lamps 58 are also supported by support assembly 60, but are able to be tilted via connected motorized racks 61 as well as move laterally relative to the center of each media piece. An operator enters via a human machine interface (HMI) geometries for the media piece to be utilized in a printing job, such as for example the length, diameter, and conical slope (if any) of the surface of the media piece, and a PC actuates movement of the gantry 56 and motorized racks 61 to accommodate the media size. A suitable PC/HMI system for the herein described operator control may be found in U.S. Ser. No. 10/710,378B, at Col. 11, line 19 through Col. 13, line 15, and FIGS. 12-13 (commonly owned by the Applicant), all of which is hereby incorporated by reference. Actual movement distances are self-generated via PC 50 and communicated electrically to a control board that issues movement commands to motors controlling the racks 61 and gantry height 77. A suitable motion control board system for the above may be found in U.S. Ser. No. 10/710,378B, at Col. 13, line 16 through Col. 14, line 47, and FIG. 13 (commonly owned by the Applicant), all of which is hereby incorporated by reference. Printer support assembly 60 moves vertically (up and down) along path 77, and UV pinning lamps 58 move laterally along path 78 and along angular path 79. Motor 63 drives a primary lifting shaft 65 via gearing assembly 64 that in turn drives three passive vertical lifting drive shafts 68. A quadrilateral gearing assembly 66 having a fixed support frame 69 fixed to gantry 56 and four corner gearing assemblies 67 connects and supports each drive shaft 68 so that when actuated rotational motor movement is converted into a coordinated level lifting motion of printing support frame 62. Frame 62 includes a plurality of slots 70 to fixedly hold printheads above each tunnel 44 and a fixed rearward placed slot 71 for a UV curing lamp.
(34) Movement of each pinning lamp 58 is achieved via a coordinated assembly of extendable plates and pivotal support bars and brackets 75. Pinning UV lamps 58 are supported by a parallel series of transverse support bars 52 that adjustably hold lamps in pre-formed slots and held in place with retaining screws. Each support bar 52 is supported at its ends by brackets 53 and 54 which in turn are supported by connecting plates 61 so that pinning lamps 58 are slidably suspended above each piece of media across and above each tunnel 44. End plates 61 are slidable held in slots formed in frame 62 so that as left most plates 61 are moved by gear 47 through gearing assembly 74, the pair of brackets 53 and 54 are moved right or left, depending upon the rotational direction of drive shaft 73 driven by servo motor 72. Brackets 53 and 54 are connected to support bars 52 via rotatable studs or fasteners 46 so that as the lateral position of brackets 53 and 54 are changed, bars 52 are correspondingly moved laterally. When actuated, servo motor 72 thereby precisely controls the lateral position of the UV lamps 58 relative to an underlying piece of media 20 positioned within tunnels 44. The lateral position of brackets 53 and 54 are also adjustable relative to one another so that as bracket 53 is advanced to the right or left relative to lower bracket 54, bars 52 are tilted about a rotational axis corresponding with the center of the lower positioned rotatable studs 46a. Therefore, changing the lateral relative positions of brackets 53 and 54 alters the angle 79 of each UV emitter 58 identically with every other UV emitter 58. A spring-loaded set pin 49 locks the relative lateral position of each bracket 53 and 54 relative to one another, and upon pulling pin 49 out slightly the two brackets may be altered relative to one another to change angle 79 as desired. A series of pin indentations or holes within right most plate 61 allow for the selection and locking of one or more pre-set angles for emitters 58 by grasping and manipulating pin 49 and rotating the UV emitters to a desired angle. The lateral position is attained by actuating motor 72 by an operator and, in the present embodiment, the angle of the UV lamps 58 is adjusted by manipulating pin 49 to allow movement and locking of emitters 58 into a desired angle relative to the adjacent printheads 57 and underlying media 20.
(35) Importantly, the above described selectable positioning of UV lamps 58 in relation to the position of the media 20 and printheads 57 minimizes the potential for UV exposure to each printhead, either directly or via transparent media reflections, as will be further discussed. As may also be noticed, the final cure UV lamp 59 is positioned well behind each bank of inkjet printing heads 57, but the UV pinning lamps 58 are positioned adjacent to each bank of printheads 57 and pointed downward and away from the bottom ink expression area (i.e. the printhead nozzle) of each printhead.
(36) Referring again to FIG. 6, printing carriage 28 is moved along path 43 and into tunnels 44. As each piece of media moves into its own respective tunnel, the media is rotated, and the surface of the media is moved axially under each printhead 57 in a coordinated fashion. As a piece of media traverses under a print head the lateral position and rotation speed of the media is precisely controlled via spindles 42 and a drive motor causing movement of printing carriage 28 via a screw shaft 48 (not shown). In addition to being rotationally controllable, spindles 42 are self-stripping and are locked against each piece of media via air cylinders at one end, but having a spring-loaded configuration thereby clamping each piece of media within the print carriage 28 at the center of each individual media spindle.
(37) As may be understood, the disclosed embodiment shows a material handling system 11 mated to printer 12 so that the disclosed configuration allows for the automation of material handling. However, printer portion 12 may be utilized separately without the automation system 11 in which case an operator would simply load each piece of media 20 directly onto printer carriage 28 by manually manipulating the spindle ends to insert a piece of media 20 for decorating within each spindle and removing a decorated piece of media 30 when complete.
(38) For the purposes of discussions on the operation of the herein described printing and ink partial curing and final curing steps, a suitable ink delivery and print engine subsystem 45 may be found in U.S. Ser. No. 10/710,378B, at Col. 6, lines 12-47; Col. 7, lines 6-12; Col. 12, line 33 through Col. 13, line 26; and FIG. 4 (commonly owned by the Applicant), all of which is hereby incorporated by reference. Referring to FIG. 8 along with Table 1 below, a power scale factor formula is presented that allows for the calculation of the minimum amount of power such that a final acceptable UV cure dosage amount may be applied to the partially cured ink present on the surface of the (now) decorated media 30. As an article having a partially cured or “pinned” image 96 traverses further within a respective tunnel 44 along path 43, it enters into an illumination zone 91 concordant with the length (91a) of UV cure lamp 59 as the object 20 continues to rotate 97 at a known speed. Each lamp has a known width 88 and a known power density as set by its manufacture. Also, each type of ink deposited onto the surface of the object 20 also has a specified amount of UV energy necessary to optimally cure the ink, which is either supplied by the manufacture of the ink or can be obtained relatively easily by empirical testing.
(39) TABLE-US-00001 TABLE 1 Where: Rotational Speed = Revolutions per Second Step Distance = mm per revolution Media Perimeter (i.e. Object Circumference at Image Printing Location on Object Surface) = π × D in mm Dose Density = m Joules per cm.sup.2 Distance of Exposure = The Lesser of Image Height or Lamp Length in mm Power Density = mW per cm.sup.2
(40) The Power Scale Factor or “PSF” in Table 1 is a dimensionless value and often is simply a scaling factor or a percentage of the maximum power density. Given the amount of energy required to cure the deposited ink and given the known amount of UV energy emitted by lamp 59, a power scale factor or PSF may be calculated using empirical UV dosage results so that the PSF may be utilized for future print jobs. This allows for the variation of various factors during printing to obtain optimal image quality on the exterior of the object 20. For example, if 20% of total dosage during pinning of an image 96 is applied, the lateral speed along path 43 and rotational speed 97 may be varied to accommodate a particular beam strength emitted from lamp 59 to achieve the remaining optimal dosage of 80%. Lamp width 88 is typically small (e.g. 20 mm) relative to the circumference of an object 20 such that redundant image exposure may be ignored. Further, each lamp 59 may include a collimator to reduce the fanning or scattering of illumination zone 91 prior to impinging upon the surface of object 20.
(41) An example PSF calculation is shown below.
(42) Given a color ink curing dose density of 146 mJ/cm.sup.2 an example calculated PSF would be:
(43)
(44) FIG. 9 shows an altered final cure step 101 to reduce the amount of UV radiation utilized in a final cure step. As object 20 moves under lamp 59, the trailing edge of image 102 (i.e. the last part of an image that must be cured as the object moves from left to right and under the cure lamp within tunnel 44) moves under lamp 59 and at some distance 103 becomes fully cured. The remaining distance under lamp 59 thereby becomes superfluous for the purpose of curing. Therefore, lamp intensity may be increased during a last portion of lateral travel 103 to finish full curing of the image 96 and then lateral movement stopped rather than moving the object the full length of the image underneath lamp 59. This procedure thereby reduces the time of printing while also reducing the amount of duration of any potentially scattered light within tunnel 44. As can be appreciated, a full number of turns under the emitter must be realized in order that all parts of image 96 receive the same minimum amount of UV radiation so that full curing is achieved. Table 2 below shows a formula for calculating the minimum number of turns required in order to achieve full curing.
(45) TABLE-US-00002 TABLE 2
(46) An example calculation is shown below calculating the minimum number of turns required for the specified equation values per Table 2. Given a 3D media having a circumference of 238.7 mm at the image location on the media, the following calculation leads to a minimum number of two (2) full turns to achieve full curing of image 96.
(47)
(48) FIG. 10 provides a further final cure option 110 for clear media. Lamp 59 includes left and right lighting segments 111,112. For clear media, left segment 111 is deactivated and only right segment 112 utilized for curing of ink on image 96, thereby removing the UV illumination field portion between location 114 and 115. This re-positions the UV source of light in tunnel 44 to the right and moving a potential source of scattered stray UV light away from ink heads 57. This option is selected through an operator inputted action via the HMI prior to the start of any print job.
(49) Referring now to FIGS. 11A-11B, and 12, it may be seen the positioning of pinning lamps relative to the printheads 57 within each tunnel 44. The adjustment of the pinning lamp position 78 is accomplished as discussed above with respect to FIGS. 7A-7F and may be controlled through an HMI presented to an operator through a display held by display mounting 24. The HMI displays the settings required for any selected piece of media and the operator makes whatever adjustments to the printer 12 that are required, including for example the lateral position of the pinning lamps, the tilt or angle of the pinning lamps in relation to the adjacent print heads, and the height of the frame member 62 over the media responsive to the diameter of the media. UV light emitted from lamp 58 is angled such that the right most edge 124 of illumination zone 91 preferably coincides with the tangential edge 123 of object 20 as it rotates 97 in a counterclockwise direction. The alignment of the right most zone edge 124 with the object edge 123 allows for the maximum emitted amount of UV light to be received on the rotating surface of the media 20 within the illumination zone 91. Further, zone 91 is optionally refined to align the emitted UV light rays with a collimator placed on lamp 58 to further reduce scattering. As shown, wet ink 119 is jetted or expressed by printhead bank 57 onto the surface of object 20 as the object rotates counter-clockwise. The wet ink 119 is then exposed to UV light when it reaches illumination zone 91 and partially hardens into a gel 121 so that the applied ink does not shift on the surface of the media 20 during further printing. This arrangement allows for the wet ink to fully spread or “wet” the surface of object 20 prior to exposure to UV radiation in zone 91. As the media rotates the slight rotational delay prior to exposure in zone 91 is important because it allows for a better artistic expression of the applied image. For example, the rotational delay allows for a more glossy, desirable image 96 to be applied to the object 20 when fully cured. Referring to FIG. 12A, clear media will expose ink to UV radiation below the potential tangency point 123 when the UV radiation passes through the clear media material, but given the rotational delay until exposure the point of UV impingement is sufficiently delayed to allow for full wetting of ink on the surface of a clear media object 20 to occur. Further, the downward UV light ray angle minimizes or even eliminates reflections on clear media so that printhead impingement does not occur. For translucent media, ink is exposed at the point of tangency 123 on the media with light scattering away from the ink heads 57 to avoid impingement. Critically, the downward angle of lamp 58 avoids UV light from impinging onto the nozzles of ink heads 57 on either type of media, thereby avoiding the fouling and deactivation of ink heads 57 during a print job when clear or semi-transparent media are being decorated. As shown, angle 120 of lamp 58 and the lateral position 116 along path 122 of lamp 58 may be adjusted in response to a geometry file associated with the dimensions of object 20 in order to optimize the positioning of lamp 58 so that the right most edge 124 of illumination zone 91 coincides with the tangency point 123. This maximizes the amount of pinning UV radiation applied to the widest possible portion of media 20 without exposing ink heads 57 to UV light, even when clear media are being printed upon with the associated potential reflections of UV light.
(50) Referring to FIG. 12B, it may be seen various positional embodiments 200 of UV lamp 58 and the effect of such positional changes on the UV illumination of rotating media 20. Inkjet print heads 57 express ink onto the surface of media 20 in a wet condition 119 as media 20 rotates counterclockwise 97. During rotation, the surface of media 20 rotates into various angular zones demarked by angles of 0 degrees 205, 90 degrees 209, 180 degrees 207, and 270 degrees 208, thereby creating four angular quadrants of 90 degrees each. A preferred illumination area 214 may also be seen consisting of plus or minus 45 degrees (212, 213) from angular point 270 degrees 208.
(51) In relation to inkjet printing heads 57, UV pinning lamp 58 may be moved into various lateral and angular positions 215 thereby altering the position of illumination field 91 issuing from lamp 58. As previously described, inkjet heads 57 and UV lamps 58 are supported by frame member 62 but also extend just below the lower surface 201 of frame member 62 so as to interact with each piece of media 62 when inside tunnels 44 during a printing operation. Lamp 58 may be adjusted to move laterally away from printheads 57 along line 203 to various a user selected distances 204(a-c) as measured from the edge of printheads 57 to a center pivot point 202 for lamp 58. Pivot point 202 corresponds with retaining grommet 46a (see FIG. 7F) to allow lamp 58 to be rotated into various user selected angles 206(a-c) as measured from a line bisecting lamp 58 and intersecting pivot point 202, thereby forming an angle 206 with line 203. Line 203 is parallel with lower surface 201 and also intersects pivot point 202 as shown. Angles thus formed may range preferably from approximately 70 degrees 206a, 95 degrees 206b, or 120 degrees 206c. As will be understood, by varying the lateral and angular position of lamp 58, a UV illumination zone or field having various coverage areas 91(a-c) relative to media 20 may be created. Each field has a right most illumination edge 124(a-c) that varies with angle and lateral position such that intersection with ink layer 119 on the surface of media 20 creates a tangency point 211(a-c) at the intersection location. Each tangency point varies in relation to the lamp position, but is preferably located within preferred angular zone 214 that maximizes the amount of power impinging upon the ink 119 during rotation while minimizing any potential for reflectivity of UV light to intersect the nozzles on printheads 57. For example, for the media size depicted in FIG. 12B, a preferred position of lateral distance 204b is combined with an angular position of 206b to produce an illumination field of 91b. UV light will therefore partially harden ink 119 as is passes through field 91b, including tangency point 211b and keeping wet ink 119 within zones 212 and 213 until gelled. By adjusting the lateral and angular position of lamp 58, a large range of media sizes and various types of inks may be accommodated within printer 12 without fouling the ink nozzles of the printheads 57 during printing.
(52) FIGS. 13A-13B show the application of exposure control so as to minimize reflections of UV light during final cure by modulating different banks of emitters in lamp 59 or by modulating the power level of all emitters in lamp 59 (FIG. 13B). FIG. 13A shows the traditional method in which the entire 3D object is moved under a curing lamp for the entire length of the object resulting in the gross scattering of UV radiation 126, likely in a direction toward a printhead 57. The same traditional approach shown in FIG. 13A applies with a UV curing lamp emitter positioned underneath the object, which is the most common industry position standard for final curing of ink on 3D objects. FIG. 13B shows the improved, modulated approach. Two levels of intensity are used for lamp 59. While an image is being printed and pinned onto the surface of object 20, the entire object is moving into illumination zone 91. As image leading edge 132 enters the start of the illumination zone 131, intensity of lamp 59 is set at a value less than full value, for example 50% of full illumination strength, but modulated to an intensity value responsive to a final UV exposure value calculated in accordance with the PSF value to achieve complete curing. Object 20 continues to move forward into the illumination zone 91 along path 43. Once image 96 has been fully printed and pinned, the intensity of lamp 59 is increased to full power, or other second higher power depending about size and length of the image and lamp intensity, and again in accordance with the PSF value. The object continues through the illumination zone 91 until the left trailing edge 133 of image 96 attains a fully cured state. Since final cure lamp 59 does not use a full power level until after image 96 is fully printed, the total amount of UV light emitted by the cure lamp 59 is greatly reduced thereby reducing the amount of stray UV light at a high-power level being potentially scattered around the printing tunnel 44 during final curing of the media 20. Since many types of transparent or translucent media include concave and convex surfaces, like for example a smooth, curved neck surface, this UV power reduction process minimizes the potential for a concentrated beam of UV light impinging upon a print head, or if it does it would do so at a reduced UV effect.
(53) FIG. 14 shows a process 140 for using the PSF formula shown in Table 1 to control values in the printing process for the system 10. The process starts 141 by calculating a PSF by using empirical observations 142. Using the PSF value, an optimal pinning lamp dosage value is determined 143 for the transparent media 20 upon which an image is to be applied. The value calculated in step 143 is then subtracted from the total optimal UV dosage amount required to fully cure the image onto the surface of the media 144. The PSF is further used to determine the final cure step parameters 146 which are then used to implement a final cure in the print job for a piece of media 147, which ends the printing of a piece of media 148. For example, an optimal media rotational speed for the printing of a piece of media in the printer can be calculated as follows:
(54) Rotational speed=(PSF×Distance of Exposure×Power Density of lamp×Lamp Width)/(Step Distance per Rev×Perimeter of Media×Dose Density)
(55) Therefore: Rotational speed=(0.25×40 mm×8000 mW/cm2×20 mm)/(5 mm/Rev×238.7 mm×146 mJ/cm2)=9.1 Rev/s or less to produce a satisfactory full cure.
(56) FIG. 15 shows the process steps for adjusting the machine 10 for use on a particular 3D media shape in order to realize the reduced printhead fouling characteristics of the herein described system in a print job. Process 150 starts 151 by obtaining the 3D object geometries 152 by either taking manual measurements of the object and inputting those values into the system HMI or by reading into the system a geometry file that specifies the geometry values representing the object from a recipe file provided for the object and its assigned image to be applied. Responsive to the geometries for the object, the height of the printheads 57 held in slots 70 is adjusted 153 up or down along path 77 via commands issued to motor 63 to raise of lower printer support assembly 60. The distance is adjusted 153 so that the printheads are optimally spaced 117 from the surface of the media to obtain the best image quality on the surface of the 3D object. Responsive to the diameter of the object, the lateral position 78 and angle 79 of the UV pinning lamp 58 is adjusted 154 relative to the central rotational axis of the media 20 in order to position the pinning lamp illumination zone edge to be coincident with the tangency 123 of the rotating 3D object surface (see FIG. 12). Using the formula for the PSF shown in Table 1, the required duration and illumination power for the pinning lamps 58 is calculated and set 155 to control the rotation rate of the media, the lateral advancement 43 and travel speed of printing carriage 28 in system 10. The ink representing an image 96 is applied and rotates into the illumination zone 91 to become gelled or “pinned” onto the surface of the object 156. This process of repeatedly applying and pinning an image onto an object surface is repeated until the print job is complete 157 and stopped 158.
(57) FIG. 16 shows process steps for adjusting the functionality of a final cure lamp to reduce the potential for printhead fouling 170. Some cure lamps 59 utilize one or more parallel segments of LED (light emitting diodes) on their illumination surface of the lamp. For those types of lamps, the printing process of system 10 starts 171 by checking to see if the final cure lamp incorporates selectable LED segments 172. If it does, segments closest to the ink printhead are deactivated 174 in each lamp 59. If the lamp does not include selectable segments, step 174 is skipped. Then, the distance for the trailing edge of the pinned image 96 to travel under the final cure lamp when the lamp is set at full power to fully and optimally cure is determined 176. The number of whole rotations of the 3D media to meet the minimum cure distance from step 176 is calculated 177 using the formula shown in Table 2. The values calculated in steps 176 and 177 are then used to implement the final cure set in the system 179. For example, assuming a non-de-activatable LED final cure lamp of 80 mm (versus a segment selectable lamp having two 40 mm segments), a calculated PSF equals [(8 rev/s×5 mm/rev×238.7 mm×143 mJ/cm.sup.2)/(800 mm lamp length×8000 mW/cm.sup.2×20 mm)=0.11 or 11%]. Therefore, the number of turns required equals [(8 rev/s×238.7 mm×146 mJ/cm.sup.2)/(20 mm×8000 mW/cm.sup.2)=1.74 turns], which would be rounded to the next higher integer of two (2) turns to ensure even image coverage. If an operator utilizes a less powerful lamp, for example 4000 mW/cm.sup.2, the PSF would then double to 0.21 and the number of turns would increase from two (2) to four (4) turns.
(58) While I have shown my invention in one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit thereof.
