System and method for pivoting a print head in a direct-to-object printer when printing on an object

Abstract

Printing system (100), comprising: a frame (130); a pair of cross members (174), each cross member (174) being parallel to a longitudinal axis of at least one printhead (118); a pair of parallel members (178) perpendicular to the pair of transverse members to form a rectangular frame (170); a rotating element (134) operatively connected to at least one of the transverse elements (174); a first actuator (146) operatively connected to the rotating member (134); at least one printhead, the at least one printhead (118) mounted on the frame (130) and configured to eject marking material; a second actuator (186) operatively connected to the frame (130), the second actuator (186) configured to rotate the frame (130) about a pivot point (182); a holder configured to hold an object (104) relative to the frame (130) and the at least one printhead (118); and a controller (124) operatively connected to the first actuator (146), the second actuator (186), and the at least one printhead (118), the controller being configured to actuate the first actuator (146) to rotate the rotating member (134) to move the frame (130) and the at least one printhead (118) in a plane bidirectionally parallel to the rectangular frame (170), wherein the controller is further configured to operate the second actuator (186) to pivot the frame (130) and the at least one printhead (118) about the pivot point (182) and to cause the at least one printhead (118) to eject marking material onto the object (104) held by the holder.

Description

[0001] This disclosure relates generally to a system for printing on three-dimensional (3D) objects, and more particularly to systems that print on ovoid or irregularly shaped objects.

[0002] Typically, commercial item printing occurs during the manufacturing process. For example, ball skins are printed with patterns or logos before the ball is completed and inflated. Consequently, a non-manufacturing operation, such as a distribution center or retail store in a region where potential product customers support multiple professional or collegiate teams, must maintain an inventory of products bearing the logos of various teams in the region. Ordering the correct number of products for each different logo to maintain inventory can be problematic.

[0003] One way to address these problems in non-production stores is to carry blank versions of the products and print the samples or logos at the point of distribution or retail store. Printers known as direct-to-object (DTO) printers were designed to print individual objects. These DTO printers have multiple print heads, typically arranged in a vertical configuration with one print head on top of another. These print heads have a fixed orientation. When the objects to be printed are egg-shaped, such as balls, water bottles, and the like, a complete image cannot be printed on the surface because part of the object's surface is removed from the flat surface of the print heads. It would be advantageous if DTO printers could print images on all or part of the egg-shaped object.

[0004] Japanese patent application JP 2001-010 032 A discloses an apparatus and method for printing a three-dimensional object, and a contact print head suitable for the apparatus. The contact print head is pressed against the medium to be printed for printing, making it possible to flexibly handle three-dimensional irregularities without being affected by changes in the distance.

[0005] The German patent application DE 10 2016 204 123 A1 relates to a method for printing an object, e.g. an aircraft fuselage, with a printed image.

[0006] Japanese patent application JP H05-318 715 A discloses a printing device for performing curved surface printing on the peripheral surface of an object such as a sphere.

[0007] The above-mentioned problem is solved by a printing system according to the invention according to claim 1. Preferred embodiments are claimed in the dependent claims.

[0008] A novel three-dimensional (3D) object printing system according to claim 1 provides flexible alignment of the print heads in the system to enable printing on most or all of the surface of an ovoid or irregularly shaped object. The printing system comprises a frame, at least one print head, the at least one print head mounted on the frame and configured to eject marking material, a first actuator operatively connected to the frame, the first actuator configured to rotate the frame about a pivotal motion, a holder configured to hold an object against the frame and the at least one print head, and a controller operatively connected to the first actuator and the at least one print head.The controller is configured to actuate the first actuator to rotate the frame and the at least one print head about the pivot point and to cause the at least one print head to eject marking material onto the object held by the holder.

[0009] The foregoing aspects and other features of a 3D object printing system and method of operating a 3D object printing system that enable printing of a majority or all of the surface of an ovoid or irregularly shaped object are explained in the following description in conjunction with the accompanying drawings. Fig. Figure 1 is a schematic diagram of the back of a DTO printer with a subsystem for pivoting the print head, which allows printing on the surface of ovoid or irregularly shaped objects. Fig. 2 is a schematic diagram of a side view of the DTO printing system used in Fig. 1 is shown. Fig. 3 is a plan view of the Fig. 1 and Fig. 2 system shown. Fig. Figures 4A to 4C show a series of printhead positions used to print the surface of an American football. Fig. Figure 5 shows a variety of shapes that the printer can print with a print head pivot system. Fig. 6 shows a process for operating the printing system of Fig. 1.

[0010] For a general understanding of the present embodiments, reference is made to the drawings. Like reference numerals have been used throughout the drawings to designate like elements.

[0011] Fig. Figure 1 shows a rear-end view of a direct-to-object printing system 100 looking toward the object being printed. The system 100 is configured with an array of printheads 118 to print on the surface of an object 104 secured within an object rotation subsystem 108. As used in this document, the word "printhead" means a component having a plurality of ejectors configured to eject marking material. The marking material ejected by an ejector depends on the marking material source to which the ejector is fluidly connected. As used in this document, the word "subsystem" refers to two or more components operated to perform a specific function within a larger system. The printheads 118 have longitudinal axes that are parallel to each other and parallel to a longitudinal axis of the object 104.The object rotation subsystem 108 includes a U-shaped frame with a base member 154 to which two vertical members 158 are attached to form the legs of the U-shaped frame. Each vertical member 158 includes an opening 162, each of which supports a shaft 126. The openings 162 may include a bearing or other component that facilitates rotation of the shafts 126 within the openings. At the end of each shaft 126 is a gripper 166 configured to hold one end or side of an object 104 to be printed. The grippers 166 are removable from the shafts 126, allowing grippers with different configurations to hold differently shaped objects to be removed and attached to the shafts.At least one shaft 126 is operatively connected to one or more actuators 122 configured to bidirectionally rotate the at least one shaft 126 and bidirectionally translate the shaft 126, as illustrated by the arrows in the figure. When the grippers 166 hold one portion of the object 104, the driven shaft 126 also rotates and translates the other shaft 126 along an axis aligned with the two shafts. The controller 124 is operatively connected to the actuator 122 and is configured to actuate the actuator 122 to move the object rotation subsystem 108 after the object 104 has been mounted in the subsystem 108. Operation of the actuator 122 by the controller 124 positions the object laterally and rotationally with respect to the print heads 118.

[0012] The print heads 118 are mounted in a support frame 130. The cross frame members are perpendicular to parallel side members 132 to form a rectangular frame, although other frame configurations are possible. The cross frame members 138 are configured with threaded openings 142, and each pair of openings receives a lead screw 134. The lead screws 134 are operatively connected to one or more actuators 146 configured to rotate bidirectionally to raise and lower the frame 130 on the lead screws 134. Alternatively, the frame 130 could be configured with an endless belt and a pair of pulleys on each side of the frame, with the pulleys driven by an actuator to rotate the belt to raise and lower the frame 130.This vertical adjustment of frame 130 positions print heads 118 and ultraviolet (UV) light curing device 150 at various positions relative to the surface of object 104 for printing and curing UV material. Support frame 130 is mounted within a pivoting frame 170. Frame 170 includes cross members 174 and vertical members 178. Lower cross member 174 is attached to a rotating shaft 182, which is operatively connected to actuator 186 for bidirectional rotation. Controller 124 is also operatively connected to actuator 186 and is configured to actuate actuator 186 to pivot frame 170 and frame 130 about shaft 182 to orient print heads 118 with respect to the surface of object 104. The controller 124 is also configured to operate the print heads 118 in the array to eject marking material onto the surface of the object 104.When one or more of the printheads 118 in the assembly 112 ejects ultraviolet (UV) marking material, the UV curing device 150 is operated by the controller 124 to cure the UV material. As used in this document, the term "UV light" refers to light having a wavelength shorter than visible light but longer than X-rays. The wavelength of such light is about 10 nm to about 400 nm. A user interface 122 is operatively connected to the controller 124 for purposes described in more detail below.

[0013] Fig. 2 is a side view of the Fig. 1. This view shows a distance measurement sensor 190 mounted at a position below the printheads 118, and the sensor is operatively connected to the controller 124. This distance sensor is configured to generate data indicative of a distance between the sensor 190 and the portion of the object 104 opposite the sensor. Since the reference point for the distance measurement performed by the sensor corresponds to the aligned front surfaces of the printheads 118, the data indicative of the distance between the sensor and the object is useful for determining the distances between the printhead surfaces and the object.As frame 130 is moved vertically relative to object 104, controller 124 receives data indicating the distance between the sensor and the surface of object 104, and the controller identifies the distance between each faceplate of printheads 118 and the portion of object 104 facing each faceplate. These distances are used by controller 124 to operate printheads 118 and create an image on the surface of the object using the marking material ejected from the printheads.

[0014] With continued reference to Fig. 2, the printheads 118 and the UV curing device 150 are mounted within sliders or channels 198 in the side members of the frame 130. One or more actuators 194 are operatively connected to the printheads 118 and the UV curing device 150 to bidirectionally move the printheads and the UV curing device within the sliders or channels toward and away from the object 104. Additionally, the one or more actuators 194 are configured to move the printheads 118 and the UV curing device 150 independently of each other to reference the distance between each printhead 118 or UV curing device 150 and the object surface with respect to the curvature or features of the object 104.

[0015] Fig. Figure 3 shows a view of the printing system 100 from above the system, looking down at the object 104. The arrows indicate the various degrees of movement possible by the printing system 100. The controller 124 can move the object 104 laterally bidirectionally by actuating the actuator 122 and can also rotate the object bidirectionally. By actuating the actuator 186, the controller 124 can rotate the frame 170 bidirectionally about the pivot shaft 182 ( Fig. 1). This movement is indicated by the curved arrows in the figure. The controller 124 also operates the actuator 194 (2) to move the print heads 118 and the UV curing device 150 toward and away from the surface of the object 104. In addition, the controller 124 actuates the actuator 146 ( Fig. 1) to move the frame 130 vertically within the frame 170 to reference the vertical position of the print heads 118 and the UV curing device with respect to the surface of the object 104.

[0016] A method for printing an elongated object, such as an American football, is described in Fig. 4A to Fig. 4C. The object 104 is held by the grippers 166 on the shafts 126 as described above. The controller 124 actuates the actuator 122 to displace one side of the object 104 relative to the print heads 118, and the controller actuates the actuator 186 to move the frame 170 and the print heads 118 into the Fig. 3A. Once the object and print head positions have been established, the print heads are operated by the controller. If the image is to cover a portion of the object that is larger than the portion immediately opposite the print heads 118, the controller can operate the actuator 122 to rotate the ball accordingly, while operating the print heads to continue printing the image around the circumference of that portion of the ball. After the first side of the object has been printed, the controller 124 operates the actuator 186 to rotate the frame 170 and the print heads 118 by the amount shown in Fig. 4B. The controller 124 actuates the actuator 122 to pivot the object to the angle shown in Fig. 4B. Once this second position has been reached, the print heads 118 are operated by the controller 124. If the image is to cover a portion of the object that is larger than the portion immediately opposite the print heads 118, the controller can actuate the actuator 122 to rotate the ball accordingly to continue the image around the circumference of that portion of the ball. After that portion of the object has been printed, the controller 124 actuates the actuator 186 to move the frame 170 and the print heads 118 by the amount shown in Fig. 4C. The controller 124 actuates the actuator 122 to move the object to expose the other side of the ball to the print heads 118, in the Fig. 4C. Once this position has been determined, the print heads 118 are operated by the controller 124. If the image is to cover a portion of the object that is larger than the portion immediately opposite the print heads 118, the controller can actuate the actuator 122 to rotate the ball accordingly, while the print heads are operated to continue printing the image around the circumference of that portion of the ball. After that side of the object has been printed, the controller 124 actuates the actuator 186 to rotate the frame 170 and the print heads 118 by the amount shown in Fig. 4C to return the printhead assembly to its home position. The grippers 166 can now be released to allow removal of the object 104 from the system 100.

[0017] Fig. Figure 5 illustrates examples of other egg-shaped shapes that can be produced by operating the printing system 100 in a similar manner as described above with respect to Fig. 4A to Fig. 4C. Data identifying these shapes can be input into the user interface 122 ( Fig. 1), and the controller 124 may use this data, for example, in the form of codes identifying the shapes and dimensions of objects mounted in the object holding subsystem 108, to determine how the print heads should be moved and positioned vertically, how the object should be moved and positioned horizontally, how the object should be rotated, how the print heads should be moved toward or away from the object, and how the frame 170 and the print heads 118 should be pivoted to print the object at various print head array positions. Alternatively, or additionally, the user interface includes an index reader, such as a bar code reader, that can obtain data identifying the object shapes and positions through markings on the object or on a label or marking affixed to or otherwise associated with the object.

[0018] A procedure for operating the printer 100 is shown in Fig. 6. In the description of the process, statements about performing a task or function refer to a controller or general-purpose processor executing programmed instructions stored in non-transitory computer-readable storage media operatively connected to the controller or processor to manipulate data or actuate one or more components in the printer to perform the task or function. The controller 124 mentioned above may be such a controller or processor. Alternatively, the controller may be implemented with more than one processor and associated circuitry and components, each configured to perform one or more tasks or functions described herein.In addition, the steps of the method may be performed in any possible chronological order, regardless of the order depicted in the figures or the order in which the processing is described.

[0019] Fig.6 is a flowchart of a process 500 that operates the printing system 100 to pivot the frame 170 and the printheads 118 to print an object 104 held in the object holding subsystem 108. The process 500 begins by operating the object holding subsystem 108 to secure the object 104 (block 504). The controller 124 operates the sensor 190 when actuating the actuators 146 to enable the controller to identify distances between the faces of the printheads 118 and portions of the object when the object faces the printhead assembly in the home position (block 508). The controller 124 also receives data from the user interface that identifies the shape and dimensions of the object to be printed (block 512).The controller 124 actuates the actuators 122, 146, 186, and 194 with respect to the shape and dimension data and the identified distances to move the object and the print heads 118 to capture contours and features of the object (block 516). The controller 124 then operates the print heads with reference to ink image data to print the portion of the object facing the print heads (block 520). This printing of the object may include rotating the object to be printed along a circumference of the portion of the object facing the print heads and further includes moving the object toward the UV curing device 150 and, if any print head has ejected UV-curable marking material, operating the device 150 to cure the UV ink to create the image on the object.When another portion of the object is to be printed (block 524), the controller 124 actuates the actuators 122, 146, 186, and 194 to reposition the object 104 and the print heads 118 for printing the next part of the object (block 516). The process then operates the print heads to print another portion of the object (block 520). This portion of the process continues until printing of the object is complete (block 524). When printing is complete, the controller 124 actuates the actuators 146, 186, and 194 to return the print heads 118 to their home position (block 528) so that the object can be released from the object holding subsystem 108.

Claims

[1] Printing system (100), comprising: a frame (130); a pair of cross members (174), each cross member (174) being parallel to a longitudinal axis of at least one printhead (118); a pair of parallel members (178) perpendicular to the pair of transverse members to form a rectangular frame (170); a rotating element (134) operatively connected to at least one of the transverse elements (174); a first actuator (146) operatively connected to the rotating member (134); at least one printhead, the at least one printhead (118) mounted on the frame (130) and configured to eject marking material; a second actuator (186) operatively connected to the frame (130), the second actuator (186) configured to rotate the frame (130) about a pivot point (182); a holder configured to hold an object (104) relative to the frame (130) and the at least one printhead (118); and a controller (124) operatively connected to the first actuator (146), the second actuator (186), and the at least one printhead (118), the controller being configured to actuate the first actuator (146) to rotate the rotating member (134) to move the frame (130) and the at least one printhead (118) in a plane bidirectionally parallel to the rectangular frame (170), wherein the controller is further configured to operate the second actuator (186) to pivot the frame (130) and the at least one printhead (118) about the pivot point (182) and to cause the at least one printhead (118) to eject marking material onto the object (104) held by the holder. [2] The printing system (100) of claim 1, wherein the rotating member (134) is a lead screw extending through a threaded hole (142) in at least one cross frame member (138). [3] The printing system (100) of claim 2, wherein the frame (130) further comprises: a pair of channels (198) for each printhead (118) in the at least one printhead, each printhead (118) in the at least one printhead being configured to slide bidirectionally in the pair of channels (198) corresponding to the printhead; a third actuator (194) operatively connected to the at least one print head (118); and the controller (124) operatively connected to the third actuator (194), the controller (124) further configured to operate the third actuator (194) to move each printhead (118) in the at least one printhead within the channels (198) bidirectionally corresponding to the printhead. [4] The printing system (100) of claim 3, wherein the at least one printhead (118) further comprises: a plurality of printheads, each printhead positioned in the one pair of channels corresponding to the printhead; and the controller (124) further configured to actuate the third actuator (194) to move each printhead (118) independently of the other printheads in the plurality of printheads. [5] The printing system (100) of claim 4, further comprising: a sensor (190) configured to generate data indicative of a distance between the sensor (190) and a portion of the object (104) in the holder opposite the sensor; and the controller (124) operatively connected to the sensor (190) to receive the data generated by the sensor (190), the controller (124) configured to identify a distance between each printhead (118) in the plurality of printheads and a portion of the object (104) opposite each printhead (118) with respect to the data generated by the sensor (190) and to actuate the third actuator (194) to move each printhead (118) in the plurality of printheads with respect to the identified distance for each printhead. [6] The printing system (100) of claim 5, wherein the controller (124) is further configured to actuate the second actuator (186) to pivot the frame (130) and the plurality of printheads (118) with respect to the identified distance for each printhead. [7] The printing system (100) of claim 6, wherein the holder further comprises: a transverse element (154); a pair of members (158) perpendicular to the cross member (154) to form a U-shaped frame, each member (158) having an opening (162); a pair of shafts (126), each shaft (126) having a first end and a second end, the second end of each shaft terminating in a gripper (166) and the first end of each shaft (126) extending mutually exclusively through the opening (162) in one of the members (158), each gripper (166) configured to hold a portion of the object (104) to secure the object (104) within the holder; a fourth actuator (122) operatively connected to the first end of one of the shafts (126), the fourth actuator (122) configured to rotate the one shaft (126); and wherein the controller (124) is operatively connected to the fourth actuator (122), wherein the controller (124) is further configured to actuate the fourth actuator (122) to rotate the one shaft (126) and the object (104) held between the grippers (166). [8] The printing system (100) of claim 7, wherein the fourth actuator (122) is further configured to move the one shaft (126) toward and away from the other shaft (126); and the controller (124) is further configured to actuate the fourth actuator (122) to move the shafts (126) and the object (104) bidirectionally along an axis aligned with the two shafts (126). [9] The printing system (100) of claim 8, further comprising: a user interface (120) operatively connected to the controller (124), the user interface (120) configured to receive shape and dimension data identifying the object (104) between the grippers (166); and wherein the controller (124) is further configured to actuate the first actuator (146), the second actuator (186), the third actuator (186), and the fourth actuator (122) with reference to the data received from the user interface (120) and identifying the shape and dimensions of the object (104) in the holder. [10] The printing system (100) of claim 9, wherein the user interface (120) further comprises: a reader for characters associated with the object (104), the characters corresponding to data identifying the shape and dimensions of the object (104) in the holder.

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