System and method for rotating a three-dimensional (3D) object while the object is being printed

Abstract

Printing system (100), comprising: at least one printhead (118), wherein the at least one printhead (118) is configured to eject drops of marking material; an element (116) having a first end and a second end; an object rotating subsystem (108) configured to hold an object (104) and move bidirectionally along the member (116) between the first end and the second end to move the object (104) past the at least one printhead (118) to enable the at least one printhead (118) to eject drops of marking material onto the object (104), the object rotating subsystem (108) comprising: a first actuator (140); a holder (212) operatively connected to the first actuator (140), the holder (212) being configured to grip a portion (136) of the object (104); a second actuator (242) having an output shaft (234); an extension (230) rotatably mounted on the output shaft (234) of the second actuator (242) to support a bottom surface of the object (104), the extension (230) abutting the bottom surface of the object (104) held at its other end by the support (212); and a controller (124) operatively connected to the first actuator (140) and the second actuator (242), the controller (124) being configured to actuate the first actuator (140) to rotate the holder (212) and the object (104) gripped by the holder (212) to enable the at least one printhead (118) to print on a portion of the circumference of the object (104) that is longer than a width of the at least one printhead (118), and to actuate the second actuator (242) to move the output shaft (234) toward and away from the object (104) to engage or disengage the extension (230) from the bottom surface of the object (104) with the object (104) held at its other end by the holder (212), and to move the object (104) after actuating the holder (212) to release the object (104) from the subsystem (108).

Description

field of technology

[0001] This disclosure relates generally to a system for printing three-dimensional (3D) objects, and more particularly to systems that print cylindrical or other rounded objects. State of the art

[0002] Commercial printing of items typically occurs during the manufacturing process. For example, the outer skins of balls are printed with patterns or logos before the ball is finished and inflated. As a result, a non-manufacturing facility, such as a distribution site or retail store, in a region where potential customers support multiple professional, amateur, or collegiate teams must maintain an inventory of products bearing the logos of various teams that have supporters in the area. Ordering the correct number of products for the different logos to maintain inventory can be problematic.

[0003] One way to address this problem at points of sale where production is not taking place is to keep blank versions of the products in stock and print them with the designs or logos at the distribution location or retail store. Printers known as direct-to-object (DTO) printers are designed to print on individual objects. These DTO printers have multiple print heads, typically arranged in a vertical array with one print head on top of another. These print heads are fixed in their orientation. If the object to be printed is rounded, such as balls, water bottles, and the like, a complete image cannot be printed on the surface because the rounded surface slopes away from the flat surface of the print heads.It would be advantageous if DTO printers were able to print images on the entire circumference of a rounded object or on a section of it.

[0004] Document US 8 931 864 B2 relates to an inkjet printer for printing at least partially cylindrical objects, comprising one or more print heads arranged over a line of travel and a carriage assembly configured to align and position an at least partially cylindrical object axially along the line of travel and then rotate the object relative to the one or more print heads. The printer further comprises a curing device arranged along the line of travel and configured to deliver energy suitable for curing the applied liquid.

[0005] Document US 2005 / 0 178 279 A1 relates to an inkjet printing system for printing an image onto an irregular surface of a material. The inkjet printing system includes a printable support that is adjustable in height and width for printing an image onto any material. The printable support is connected to a computer system to provide an image to be printed onto a material. The material includes irregular surfaces for common household objects, including tiles, wood, glass, marble, ornaments, and the like, regardless of the shape or composition of the material.

[0006] Document US 9 221 275 B2 relates to a container printing device for printing graphic, numeric, and / or alphanumeric information or an image onto an outer surface of a bottle or similar container. The device comprises at least one electrostatic printhead having a plurality of orifices for dispensing printing fluid and a plurality of corresponding electrodes. The orifices are arranged in a row one behind the other along a longitudinal axis of the printhead. A container handling assembly is used to position a container adjacent to the at least one electrostatic printhead so that printing fluid can be dispensed onto an outer surface of the container.

[0007] The document CN 1 06 739 542 A relates to a fully automatic, rotating printing machine for the digital printing of curved surfaces by means of inkjet printing, the document WO 2015 / 036 571 A1 relates to a printing machine for the digital printing of 3-dimensional objects and the document DE 10 2014 218 361 A1 also relates to a device for treating containers, such as plastic bottles, by direct printing. Summary

[0008] A new printing system for three-dimensional (3D) objects enables the printing of most or all of the circumference of rounded objects. The printing system comprises at least one print head, the at least one print head being configured to eject marking material, a member having a first end and a second end, an object rotating subsystem configured to hold an object and move bidirectionally along the member between the first end and the second end to move the object past the at least one print head to enable the at least one print head to eject drops of marking material onto the object, the object rotating subsystem comprising: a first actuator, a mount operatively connected to the first actuator, the mount being configured to grip a portion of the object, a second actuator,which has an output shaft; an extension rotatably mounted on the output shaft of the second actuator to support a bottom surface of the object, the extension abutting the bottom surface of the object held at its other end by the holder; and a controller operatively connected to the first actuator and the second actuator. The controller is configured to actuate the first actuator to rotate the holder and the object gripped by the holder to enable the at least one printhead to print on a portion of the circumference of the object that is longer than a width of the at least one printhead, and to actuate the second actuator to move the output shaft toward and away from the object to engage or disengage the extension from the bottom surface of the object, the object being held at its other end by the holder.and to remove the object from the subsystem after actuating the holder to release the object. Short description of the drawings:

[0009] The above aspects and other features of a printing system for rotating objects that enable printing around most or all of the circumference of rounded objects are explained in the following description in conjunction with the accompanying drawings. Fig. Figure 1A is a schematic diagram of a DTO printing system with an object rotation subsystem that enables printing around most or all of the circumference of rounded objects. Fig. Figure 1B is a schematic sketch of a view of the subsystem for rotating objects of Fig. 1A from a print head that sprays material onto the object held by the subsystem. Fig. Figure 2 shows an embodiment of the subsystem for rotating objects used in the printing system of Fig. 1 is used. Fig. 3A shows a process for operating the printer of Fig. 1, which rotates an object held by the object rotation subsystem. Fig. Figure 3B shows an alternative process for actuating the printer from Fig. 1, which rotates an object held by the object rotation subsystem. Fig. Figure 4 shows the printing of unconnected sectors of the circumference of the object held by the object rotating subsystem shown in Fig. 1A is shown. Fig. Figure 5 shows a continuous printing of the circumference of the object held by the object rotating subsystem shown in Fig. 1A is shown. Detailed description

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

[0011] Fig. Figure 1A shows a side view of a direct-to-object (DTO) printing system 100 configured to print on the surface of an object 104 secured within an object-rotating subsystem 108, while the subsystem 108 moves the object 104 past an array 112 of printheads 118. As used herein, the word "printhead" refers to a component having multiple ejectors configured to eject marking material. The marking material ejected by an ejector depends on the marking material source with which the ejector is in fluid communication. The object-rotating subsystem 108 slides bidirectionally along an element 116, as indicated by the arrow in the figure. The controller 124 is configured to actuate the actuator 128 to move the object rotating subsystem 108 after the object 104 has been mounted in the subsystem 108.The controller 124 is also operatively connected to an actuator 138 configured to move either the subsystem 108 or the printhead assembly 112, or both, toward or away from each other. A distance sensor 142 is associated with the printhead assembly 112. The sensor 142 is configured to generate signals corresponding to a distance between the printhead assembly 112 and the object 104 when the object 104 is opposed to the printhead assembly. The controller 124 receives these signals and actuates the actuator 138 to move the printhead assembly 112 or the subsystem 108, or both, with respect to each other. The controller 124 is configured to actuate the printheads 118 in the assembly 112 to eject marking material onto the surface of the object 104.If one or more of the printheads 118 in the array 112 ejects ultraviolet (UV) marking material, the UV curing device 120 is actuated by the controller 124 to cure the UV material. As used herein, "UV light" refers to light with a wavelength shorter than visible light but longer than X-rays. The wavelength of such light is from about 10 nm to about 400 nm.

[0012] An embodiment of the subsystem 108 is shown in Fig. 1B from a perspective opposite the printhead. The subsystem 108 includes a pair of sockets 132 in which the element 116 is received. At least one of the sockets 132 is operatively connected to the actuator 128 so that the controller 124 can actuate the actuator 128 to move the subsystem 108 bidirectionally along the element 116. Bidirectional movement is referred to as single-process direction movement. In the configuration shown in the figure, the actuators 140 and 242 are offset from the element 116. The printheads 118 are offset cross-process direction with respect to the longitudinal axis of the element 116 to enable the printheads to eject marking material toward the object 104 held by the subsystem 108.Likewise, the UV curing device 120 is offset transversely to the process direction to enable the UV curing device to direct UV light onto the image on the object 104 to cure UV-curable material on the object. The actuator 140 is mechanically connected to one of the bushings 132 and is operatively connected to the controller 124. A bracket 212 is mounted on the output shaft 144 of the actuator 140. The bracket 212 is configured to grip and hold a portion 136 of the object 104 while the actuator 140 is actuated by the controller 124 to rotate the object 104, as described in more detail below. An extension 230, rotatably mounted on the output shaft 234 of the actuator 242, supports the bottom of the object 104.The actuator 242 is connected to a bushing 132, and the actuator 242 translates its output shaft 234 toward and away from the object 104, thereby enabling an object 104 to be installed and removed from the object rotating subsystem 108, as described in detail below.

[0013] Fig. Figure 2 is an illustration of one embodiment of the object rotating subsystem 108 that may be used in the printing system 100. As used in this document, the word "subsystem" refers to two or more components that are actuated to perform a particular function within a larger system. Although Fig. 2, the controller 124 actuates the actuator 128 to move the bushings 132 and the subsystem 108 past the printhead assembly 112 and the UV curing device 120 in the process direction, as described above with reference to Fig. 1B. As in Fig. 1B and Fig. 2, the actuator 140 of the subsystem 108 may be an electric motor having an output shaft 144 to which a bracket 212 is mounted. Fig. 2 further shows the actuator 140, which is electrically connected to a source of electrical power 216 via an electrical switch 220. The controller 124 is operatively connected to the electrical switch 220 to enable the controller to actuate the switch 220 and selectively connect the actuator 140 to electrical power. Once at least a portion 136 of an object 104 is secured within the holder 212, the controller 124 can actuate the actuator 140 via the switch 220 to rotate the object. As the object rotating subsystem 108 moves past the print heads 118 in the assembly 112 ( Fig. 1A), the rotation of the object allows the circumference of the object to be printed largely or completely by one or more of the print heads. In an embodiment shown in Fig. 2, a rotary encoder 224 is positioned proximate the output shaft of actuator 140 to enable controller 124 to receive an electrical signal generated by the encoder indicative of the position of shaft 144. Controller 124 is configured with software that enables the controller to process the electrical signals from encoder 224 and detect the portion of the periphery of object 104 that faces a print head 118 so that a portion of an image can be printed on the object. In an alternative embodiment, actuator 140 is a stepper motor, and controller 124 detects the position of the object gripped by chuck 212 by reference to the pulses sent to the actuator to rotate the chuck and object.In this embodiment, the encoder is not required to enable the controller to detect the portion of the object surface facing the print heads.

[0014] The fixture 212 may be a known collet chuck, a three-jaw chuck, a collar configured to grip a structure disposed at an outermost end of an object to be printed, a granular material fixture, or the like. As used in this document, the word "fixture" means any device configured to secure an object to be printed. As used in this document, the words "collar" and "chuck" mean a planar member having an opening and at least one movable member that varies the size of the opening to selectively secure an object in a predetermined orientation. A chuck is capable of rotating in a first direction to move the at least one movable member of the chuck into the opening within the chuck to secure an object in a known manner. Reversing the rotation of the chuck releases the object within the collar.In another embodiment of a chuck, the movable elements of the chuck come together at the center of the opening within the chuck, and rotation of the chuck in the first direction moves the elements toward the periphery of the opening so that the elements can be inserted into an opening of an object, for example, the mouth of a bottle, and rotation in the first direction urges the elements against the periphery of the object opening to hold the object for printing. Reversing the rotation of the chuck brings the elements together at the center of the opening to relieve the pressure against the periphery of the object opening to allow the object to be removed.As used in this document, the term "granular material fixture" means a conformable container filled with granules, the interior of which is in fluid communication with an air extraction and air compression source to permit removal of air between grains of the granules to secure a portion of an object under deformation of the container and to force air between grains to release the object portion.

[0015] As in Fig. 2, the output shaft 234 of the actuator 242 in the object rotating subsystem 108 includes an extension 230 that bears against the bottom of the object 104. The extension 230 is rotatably mounted to the output shaft 234 by a bearing or the like. As the actuator 140 rotates the object 104, the extension 230 rotates about the output shaft 234 to enable rotation of the object. The output shaft 234 is operatively connected to the actuator 242, which is configured to move the output shaft 234 bidirectionally in the vertical direction. The controller 124, which is operatively connected to the actuator 242, actuates the actuator 242 to move the extension 230 to a position where the extension 230 abuts a bottom surface of the object 104, which is held at its other end by the support 212.In this position, the extension 230 helps support the object 104 during printing and while it rotates freely while the actuator 140 rotates the output shaft 144 and the object 104. Actuation of the actuator 242 varies the distance between the extension 230 and the support 212 to accommodate objects of different lengths. Once the object has been printed and the subsystem 108 returns to its home position, the support 212 is actuated to release one end of the object 104, and the actuator 242 is actuated to lower the extension 230 so that the object 104 can be removed from the subsystem 108.

[0016] A process of operating the printer 100 is shown in Fig. 3. In the description of the process, statements that the process performs a particular task or function refer to a controller or general-purpose processor executing programmed instructions stored in a non-transitory, computer-readable storage medium operatively connected to the controller or processor to control one or more components in the printer to perform the task or function. The controller 124 noted 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.Furthermore, the steps of the method may be performed in any possible chronological order, regardless of the order shown in the figures or the order in which the processing is described.

[0017] Fig. 3A is a flowchart of a process that implements the rotation of the printed object to be printed, which has been described above with each embodiment of the object rotation subsystem 108. The process 300 begins with the holder 212 being actuated to secure the object 104 within the subsystem 108 and the actuator 242 being actuated to support the bottom of the object with the extension 230 (block 304). The controller 124 actuates the actuator 128 to move the object 104 past the printheads 118 in the array 112, while the controller actuates the printheads to print the sector of the object facing the printheads (block 308). If another sector of the object is to be printed (block 312), the controller 124 actuates the actuator 140 to rotate the object 104 to the next sector to be printed after the object has passed the last print head 118 in the array 112 (block 316).The controller 124 actuates the actuator 128 to move the object past the print heads 118 in the opposite direction so that the print heads can print the sector facing the print heads (block 312). This process of rotating the object and then moving it past the print heads continues until all sectors on the object's perimeter that need to be printed have been printed. At this point, the controller 124 actuates the actuator 128 to return the object to its home position (block 320), where it can be released from the holder 212 (block 324).

[0018] A flowchart of an alternative process that implements the printing of an object held by one of the two embodiments of the rotating object subsystem 108 is shown in Fig. 3B. The process 350 begins by actuating the fixture 212 to secure the object 104 in the subsystem 108 and actuating the actuator 242 to support the bottom of the object with the extension 230 (block 354). The controller 124 actuates the actuator 128 to stop the object opposite one of the print heads 118 in the array 112 (block 358). An operator can enter data identifying the object configuration before the object is printed. If the object is not cylindrical (block 362), the object sector opposite the print head is printed (block 366), and the process determines whether a different object sector should be printed (block 370).The printing performed by the processing in block 366 may include moving the object vertically by a small increment to print the sector if the vertical height of the image is greater than the height of the ejector assembly in the printhead currently being used to print the sector.If a different sector is to be printed, the controller 124 actuates the actuator 138 to move the assembly 112, the subsystem 108, or both with respect to each other, with reference to the signals from the sensor 142, before rotating the object (block 374). Once the object and the assembly have been separated a suitable distance to allow rotation of the object without impacting the assembly, the object is rotated by the controller 124 actuating the actuator 138 (block 378), and the object is returned to a distance suitable for printing other sectors of the non-cylindrical object (block 382). That sector is printed (block 366), and the process continues until all sectors for the object's circumference opposite the print head have been printed (block 370).When all sectors of the current outer edge have been printed, the process determines whether the outer edge should be printed with a different printhead (block 386). If so, the processing of blocks 358 through 382 is repeated to print the outer edge with a different printhead. Once the outer edge has been printed by all printheads, the object is returned to its home position (block 390) and released from the holder (block 394). If the object is cylindrical, it can be rotated without hitting the printheads. In this situation, the first printhead the object stopped at is actuated to print the perimeter of the object while the object is rotated (block 396).The printing performed by the processing in block 396 may involve moving the object vertically by a small increment to print the sector if the vertical height of the image is greater than the height of the radiator array in the printhead currently being used to print the sector. If the perimeter is to be printed with a different printhead (block 386), the object is moved relative to the printhead (block 358) and rotated while being printed by the printhead (block 396). This process continues until all printheads have printed the perimeter. At this time, the object is returned to its home position (block 390) and released from the holder (block 394).

[0019] The rotation of object 104 in the processes of Fig. 3A and Fig. 3B may present another portion of the perimeter or outer edge for printing that is spaced from the first printed portion by a predetermined distance, as in Fig. 4. Thus, different sectors of a circumference or outer edge of the object can be printed to avoid a protrusion or a depression in the surface, such as a handle. Cylindrical objects can be printed by the process of Fig. 3B in block 396 to enable printing of a continuous image around most or all of the circumference of the object 104, as in Fig. 5. In the process of Fig. 3A, the rotation of the object that occurs after the object has passed the print head can present either disjoint sectors for printing or contiguous sectors for printing, regardless of the configuration of the object.

[0020] It should be appreciated that variations of the above-disclosed devices and other features or functions, or alternatives thereto, may be combined as desired to form many other different systems or applications. For example, although the above-described embodiments have been described with a vertical configuration, the printing system and object rotating subsystem may be configured to move an object through a printer in a different direction. Various alternatives, modifications, variations, or improvements may be made by one skilled in the art, and are also intended to be encompassed by the following claims.

Claims

[1] Printing system (100), comprising: at least one printhead (118), wherein the at least one printhead (118) is configured to eject drops of marking material; an element (116) having a first end and a second end; an object rotating subsystem (108) configured to hold an object (104) and move bidirectionally along the member (116) between the first end and the second end to move the object (104) past the at least one printhead (118) to enable the at least one printhead (118) to eject drops of marking material onto the object (104), the object rotating subsystem (108) comprising: a first actuator (140); a holder (212) operatively connected to the first actuator (140), the holder (212) being configured to grip a portion (136) of the object (104); a second actuator (242) having an output shaft (234); an extension (230) rotatably mounted on the output shaft (234) of the second actuator (242) to support a bottom surface of the object (104), the extension (230) abutting the bottom surface of the object (104) held at its other end by the support (212); and a controller (124) operatively connected to the first actuator (140) and the second actuator (242), the controller (124) being configured to actuate the first actuator (140) to rotate the holder (212) and the object (104) gripped by the holder (212) to enable the at least one printhead (118) to print on a portion of the circumference of the object (104) that is longer than a width of the at least one printhead (118), and to actuate the second actuator (242) to move the output shaft (234) toward and away from the object (104) to engage or disengage the extension (230) from the bottom surface of the object (104) with the object (104) held at its other end by the holder (212), and to move the object (104) after actuating the holder (212) to release the object (104) from the subsystem (108). [2] The printing system (100) of claim 1, wherein the holder (212) is a chuck. [3] The printing system (100) of claim 1, wherein the first actuator (140) connected to the mount (212) is a stepper motor. [4] The printing system (100) of claim 3, wherein the object rotating subsystem (108) further comprises: a rotary encoder (224) configured to generate an electrical signal indicative of an angular displacement of the output shaft (234) of the first actuator (140); and wherein the controller (124) is further configured to process the electrical signals generated by the rotary encoder (224) to identify a position of a surface of the object (104). [5] The printing system (100) of claim 4, wherein the object rotating subsystem (108) further comprises: a source (216) of electrical power; an electrical switch (220) operatively connected to the electrical power source (216) and the first actuator (140); and wherein the controller (124) is operatively connected to the electrical switch (220), the controller (124) further configured to actuate the electrical switch (220) to selectively connect the source (216) of electrical power to the first actuator (140). [6] The printing system (100) of claim 5, further comprising: a third actuator (128) connected to the object rotating subsystem (108); and wherein the controller (124) is operatively connected to the third actuator (128), wherein the controller (124) is further configured to actuate the third actuator (128) connected to the object rotating subsystem (108) to rotate the object rotating subsystem (108) in a process direction. [7] The printing system (100) of claim 6, further comprising: a fourth actuator (138) operatively connected to the object rotating subsystem (108) or the at least one print head (118), the fourth actuator (138) being configured to move the object rotating subsystem (108) or the at least one print head (118) relative to each other; and wherein the controller (124) is operatively connected to the fourth actuator (138), the controller (124) further configured to actuate the fourth actuator (138) to rotate the object rotating subsystem (108) or the at least one print head (118) relative to each other. [8] The printing system (100) of claim 7, further comprising: a sensor (142) configured to generate signals corresponding to a distance between the at least one print head (118) and the object rotating subsystem (108) when the object rotating subsystem (108) is positioned opposite the at least one print head (118), and wherein the controller (124) is operatively connected to the sensor (142), the controller (124) being further configured to actuate the fourth actuator (138) connected to the object rotating subsystem (108) with reference to the signals received from the sensor (142) to rotate the object rotating subsystem (108) or the at least one print head (118) relative to each other. [9] The printing system (100) of claim 2, wherein the controller (124) is further configured to rotate the chuck and the object (104) gripped by the holder (212) to enable the at least one printhead (118) to eject marking material onto at least two portions of the circumference of the object (104) separated by a predetermined distance, the two portions and the predetermined distance together being greater than a width of the at least one printhead (118). [10] The printing system (100) of claim 2, wherein the controller (124) is further configured to rotate the chuck and the object (104) gripped by the holder (212) to enable the at least one printhead (118) to eject marking material onto a contiguous portion of the circumference of the object (104) whose length is at least greater than a width of the at least one printhead (118) and may be as long as one complete rotation of the object (104).

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