Service station for 3D printing systems

Abstract

A service station system for a three-dimensional printing system is provided. The system includes a vat having a quick-release connector on a front side and a hinge on a rear side, with its open top surface hingedly connectable to a surface of the three-dimensional printing system, and a wiper assembly having a wiper device removably connected to a wiper base on a rotatable shaft that passes through the vat. The wiper device wipes the ejection face of a print head of the three-dimensional printing system while the head reciprocates between the rear and front sides of the vat. The service station system may also include a motor for rotating the shaft.

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 015,741, filed April 27, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention, in some embodiments thereof, relates to three dimensional printing, and more particularly, but not exclusively, to a service station for three dimensional printing. [Background technology]

[0003] Additive manufacturing (AM) is a technology that allows arbitrarily shaped structures to be produced directly from computer data through additive forming steps. The basic operation of any AM system consists of slicing a three-dimensional computer model into thin cross-sectional sections, converting the results into two-dimensional positional data, and feeding that data to a controller that builds the three-dimensional structure layer by layer.

[0004] Additive manufacturing involves many different approaches to manufacturing, including three-dimensional (3D) printing, such as 3D inkjet printing. 3D inkjet printing is accomplished by inkjet printing and depositing a build material layer by layer. Thus, the build material is ejected from an ejection head with a set of nozzles and deposited in layers onto a support structure. The layers are then leveled by a leveling device and cured or solidified.

[0005] Various three-dimensional printing techniques exist and are disclosed, for example, in commonly assigned U.S. Patent Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510, 7,500,846, 7,962,237, 8,784,723, 9,031,680, and 10,611,136, the contents of which are incorporated herein by reference. Summary of the Invention

[0006] According to an aspect of some embodiments of the present invention, there is provided a service station system for three-dimensional printing. The printing system has at least one print head. The service station system includes a vat having a quick-release connector at a front side and a hinge at a rear side, such that the open top side of the vat is hinged to a surface of the three-dimensional printing system. The service station system can also include a wiper assembly having a wiper device removably connected to a wiper base mounted on a rotatable shaft that passes through the vat. The wiper device is optionally and preferably configured to wipe the ejection face of the print head as the head moves back and forth over the vat between its rear and front sides. The service station system can include a motor for rotating the shaft.

[0007] According to some embodiments of the present invention, the wiper assembly includes a shaft, the wiper base being mounted to a rotatable axle by the shaft, the shaft being rotatable independently of and perpendicular to rotation of the axle by the motor.

[0008] According to one aspect of some embodiments of the present invention, there is provided a service station system for a three-dimensional printing system. The printing system has at least one print head. The service station system includes a vat having a front side, a rear side, and an open top side, and a wiper assembly including a wiper device and a wiper base removably connected to the wiper device and attached by a shaft to a rotatable axle that passes through the vat. The wiper device is configured to wipe the ejection face of the print head as the print head moves back and forth over the vat between its rear side and front side. A motor for rotating the axle is also included.

[0009] According to some embodiments of the present invention, the shaft is inclined relative to the horizontal.

[0010] According to some embodiments of the present invention, the wiper assembly includes a shielding structure for shielding the connection between the shaft and the axis from liquid build material wiped by the wiper device or displaced by the printhead.

[0011] According to some embodiments of the present invention, the service station system includes a liquid trap covering an upper surface and having a plurality of perforated liquid guide channels for collecting liquid build material wiped off by a wiper device or expelled by a print head.

[0012] According to an aspect of some embodiments of the present invention, there is provided a service station system for a three dimensional printing system having at least one print head, the service station system including: a vat having a front surface, a back surface, and an open top surface; a wiper assembly having a wiper device configured to wipe the discharge face of the print head as the head moves back and forth over the vat between the back surface and the front surface; and a liquid trap covering the top surface and having a plurality of perforated liquid-guiding channels for collecting liquid build material wiped by the wiper device or expelled by the print head.

[0013] According to some embodiments of the present invention, the number of grooves is equal to the number of build material channels in the at least one print head.

[0014] According to some embodiments of the present invention, the groove is perforated at multiple locations along its length, excluding a location near the wiper assembly.

[0015] According to some embodiments of the present invention, the wiper device is oriented substantially perpendicular to the index direction of the three dimensional printing system.

[0016] According to some embodiments of the present invention, the width of the wiper device is at least the width of the entire print head of the three dimensional printing system.

[0017] According to some embodiments of the present invention, the wiper device is oriented substantially parallel to the index direction of the three dimensional printing system.

[0018] According to some embodiments of the present invention, the width of the wiper device is at least the length of the print head.

[0019] According to some embodiments of the present invention, the wiper device comprises an elastomeric wiping element that is substantially straight and has a wiping edge that is continuous across its width.

[0020] According to some embodiments of the present invention, the wiper device comprises an elastomeric wiping element characterized by a Shore A hardness of about 70 to about 90.

[0021] According to some embodiments of the present invention, the elastomeric wiping element comprises a synthetic rubber.

[0022] According to some embodiments of the present invention, the synthetic rubber comprises ethylene propylene diene.

[0023] According to some embodiments of the present invention, a wiper device comprises an elastomeric wiping element connected to a resilient non-polymeric planar structure.

[0024] According to some embodiments of the present invention, the resilient non-polymeric planar structure is metallic.

[0025] According to some embodiments of the present invention, a quick release connector includes a latch assembly.

[0026] According to some embodiments of the present invention, the latch assembly comprises a curved, resilient wire shaped to support the tub from below.

[0027] According to an aspect of some embodiments of the present invention there is provided a printing system for three dimensional printing comprising at least one print head for dispensing build material and a service station system as described above and optionally and preferably in more detail below.

[0028] According to some embodiments of the present invention, the printing system includes a computerized controller configured to control at least one print head to periodically visit a service station system to wipe the ejection surface and / or expel build material into a reservoir.

[0029] According to an aspect of some embodiments of the present invention, there is provided a printing system for three-dimensional printing. The printing system includes at least one print head for dispensing build material, a service station system having a motor, a backlight source, and a computerized controller configured to control the print head and the service station system. The service station system optionally and preferably includes: (a) a vat having a front surface and a rear surface; (b) a wiper assembly having a wiper device removably connected to a wiper base mounted on a rotatable shaft that passes through the vat, the wiper device configured to wipe the discharge face of the print head as the head reciprocates between the rear surface and the front surface; and (c) a motor for rotating the shaft. The backlight source is preferably positioned behind the vat such that light from the backlight source passes between the wiper device and the discharge face when the wiper device disengages from the discharge face and is blocked by the wiper device when the wiper device engages the discharge face.

[0030] According to some embodiments of the present invention, the computerized controller is configured to automatically activate the backlight source when the motor rotates the shaft.

[0031] According to an aspect of some embodiments of the present invention, there is provided a method of printing a three-dimensional object, the method including receiving three-dimensional printing data corresponding to a shape of the object, providing the data to a printing system as described above and optionally and preferably in more detail below, and periodically moving at least one print head to visit a service station system to wipe a dispensing surface and / or empty build material into a reservoir.

[0032] According to an aspect of some embodiments of the present invention, there is provided a method for aligning a wiper device in a three dimensional printing system having at least one print head and a wiper device, the method including: moving the print head to a position above the wiper device, back-illuminating the print head and the wiper device so that light passes therebetween, and decreasing a vertical distance between the wiper device and the print head until the wiper device blocks the light.

[0033] According to some embodiments of the present invention, the wiper device includes an elastomeric wiping element, and the method includes increasing the vertical distance when the wiper device blocks light to reduce the stress that the print head applies to the elastomeric wiping element.

[0034] According to an aspect of some embodiments of the present invention, there is provided a method of performing maintenance on a three dimensional printing system including a service station system as described above and optionally and preferably in more detail below, the method including releasing a quick release connector to hinge a front face of the tub downward to expose a wiper base, removing the wiper device from the wiper base, and removably connecting a replacement wiper device to the wiper base.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, exemplary methods and / or materials are described below. In case of conflict, the present specification, including definitions, will control. Furthermore, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0036] Implementation of the method and / or apparatus of embodiments of the present invention may involve performing or completing selected tasks manually, automatically, or a combination thereof. Furthermore, depending on the actual instrumentation and installation of the method and / or apparatus embodiments of the present invention, some selected tasks may be performed by hardware, or by software or firmware using an operating system, and / or a combination thereof.

[0037] For example, hardware for performing selected tasks according to embodiments of the present invention may be implemented as a chip or circuit. With respect to software, selected tasks according to embodiments of the present invention may be implemented as a plurality of software instructions executed by a computer using any suitable operating system. In exemplary embodiments of the present invention, one or more tasks according to exemplary embodiments of the methods and / or apparatuses described herein are performed by a data processor, such as a computing platform, executing a plurality of instructions. Optionally, the data processor includes volatile memory for storing instructions and / or data, and / or non-volatile storage, such as a magnetic hard disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is also provided. A display and / or user input device, such as a keyboard or mouse, are also optionally provided.

[0038] Some embodiments of the present invention are herein described, by way of example only, with reference to the accompanying drawings. Referring now specifically to the drawings in detail, it is emphasized that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken together with the drawings will make apparent to those skilled in the art how embodiments of the present invention may be carried out. [Brief explanation of the drawings]

[0039] [Figure 1A] FIG. 1 is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1B]FIG. 1 is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1C] FIG. 1 is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1D] FIG. 1 is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 2A] FIG. 1 is a schematic diagram of a printhead according to some implementations of the present invention. [Figure 2B] FIG. 1 is a schematic diagram of a printhead according to some implementations of the present invention. [Figure 2C] FIG. 1 is a schematic diagram of a printhead according to some implementations of the present invention. [Figure 3A] FIG. 2 is a schematic diagram illustrating coordinate transformation according to some implementations of the present invention. [Figure 3B] FIG. 2 is a schematic diagram illustrating coordinate transformation according to some implementations of the present invention. [Figure 4A] FIG. 1 is a schematic diagram illustrating a top view of a three dimensional printing system including a service station system according to some implementations of the present invention. [Figure 4B] FIG. 1 is a schematic diagram illustrating a top view of a three dimensional printing system including a service station system according to some implementations of the present invention. [Figure 5A] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5B] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5C] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5D] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5E] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5F] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5G] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 5H] 1 is a schematic diagram illustrating several views of a service station system according to some implementation embodiments of the present invention. [Figure 6A] 1 is a schematic diagram of a wiper assembly according to some embodiments of the present invention. [Figure 6B] 1 is a schematic diagram of a wiper assembly according to some embodiments of the present invention. [Figure 6C] 1 is a schematic diagram of a wiper assembly according to some embodiments of the present invention. [Figure 6D] 1 is a schematic diagram of a wiper assembly according to some embodiments of the present invention. [Figure 7] FIG. 1 is a flow diagram illustrating a method suitable for positioning a wiper device in a three dimensional printing system, according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present invention, in some embodiments thereof, relates to three dimensional printing, and more particularly, but not exclusively, to a service station for a three dimensional printing system.

[0041] Before describing at least one embodiment of the present invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples. The invention is capable of other embodiments and of being practiced or carried out in various ways.

[0042] The present method and system fabricates a three-dimensional object layer-by-layer by forming multiple layers in a construction pattern that corresponds to the shape of the object based on computer object data, which may be in any known format, including but not limited to Standard Tessellation Language (STL) or Stereolithography Contour (SLC) format, OBJ file format (OBJ), 3D Manufacturing Format (3MF), Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Interchange Format (DXF), Polygon File Format (PLY), or any other format suitable for computer-aided design (CAD).

[0043] As used herein, the term "object" refers to the entire object or a portion thereof.

[0044] Each layer is formed by an additive manufacturing device that scans a two-dimensional surface to pattern it. During scanning, the device visits multiple target locations on the two-dimensional layer or surface and, for each target location or group of target locations, determines whether and what type of build material should be delivered to that target location or group of target locations. The decisions are made according to a computer image of the surface.

[0045] In preferred embodiments of the present invention, AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments, build material is ejected from a printhead having one or more nozzle arrays to deposit the build material layer by layer onto a support structure. The AM device thus ejects build material at target locations to be covered, leaving other target locations empty. The device typically includes multiple nozzle arrays, each configurable to eject a different build material. This is typically achieved by providing a printhead with multiple fluid channels that are isolated from one another and not in fluid communication with one another. Each channel receives a different build material through a separate inlet, which delivers it to a separate array of nozzles.

[0046] Thus, different target locations can be occupied by different build materials. Build material types are broadly divided into two categories: build materials and support materials. Support materials act as a support matrix or structure to support an object or portion of an object during the manufacturing process and / or for other purposes, such as providing a hollow or porous object. Support structures may also include additional build material elements, for example, to provide additional support strength.

[0047] Build materials are generally compounds formulated for use in additive manufacturing that are capable of forming three-dimensional objects by themselves, i.e., without the need for mixing or combining with any other substances.

[0048] The final three-dimensional object may be made from the build material, or a combination of build materials, or a build material and a support material, or variations thereof (e.g., after hardening), all of which are well known to those skilled in the art of solid freeform molding.

[0049] In some exemplary embodiments of the invention, an object is fabricated by dispensing two or more different build materials, each material dispensed through a different nozzle array (on the same or different print head) of the AM device. In some embodiments, two or more such nozzle arrays dispensing different build materials are all located on the same print head of the AM device. In some embodiments, the nozzle arrays dispensing different build materials are located on separate print heads. For example, a first nozzle array dispensing a first build material is located on a first print head, and a second nozzle array dispensing a second build material is located on a second print head.

[0050] In some embodiments, both the nozzle arrays that eject the build material and the nozzle arrays that eject the support material are located on the same print head, while in some embodiments, the nozzle arrays that eject the build material and the nozzle arrays that eject the support material are located on separate print heads.

[0051] A representative, non-limiting example of a system 110 suitable for AM of an object 112 according to some embodiments of the present invention is shown in Figure 1A. The system 110 includes an additive manufacturing device 114 having a dispensing unit 16 with multiple print heads. Each head preferably includes one or more nozzle arrays 122 typically mounted in an orifice plate 121, as shown in Figures 2A-2C described below, through which a liquid build material 124 is dispensed.

[0052] Preferably, but not necessarily, device 114 is a three-dimensional printing device, in which case the print head is an inkjet print head and the build material is dispensed via inkjet technology. This need not be the case, as some applications may not require the additive manufacturing device to use three-dimensional printing technology. Representative examples of additive manufacturing devices contemplated by various exemplary embodiments of the present invention include, but are not limited to, fused deposition modeling devices and fused material deposition models.

[0053] Each print head is optionally and preferably fed via one or more build material reservoirs, which may optionally include a temperature control unit (e.g., a temperature sensor and / or a heating device) and a material level sensor. To eject the build material, a voltage signal is applied to the print head, selectively depositing droplets of material through the print head nozzles, as in, for example, piezoelectric inkjet printing technology. Another example is a thermal inkjet print head. These types of heads have heater elements in thermal contact with the build material, and a voltage signal activates the heater elements to heat the build material and form gas bubbles therein. The gas bubbles generate pressure in the build material, causing droplets of the build material to be ejected through the nozzles. Piezoelectric and thermal print heads are known to those skilled in the art of solid free-form molding. For any type of inkjet print head, the ejection speed of the head depends on the number of nozzles, the type of nozzle, and the applied voltage signal rate (frequency).

[0054] Preferably, but not necessarily, the total number of ejection nozzles or nozzle arrays is selected so that half of the ejection nozzles are for ejecting support material and half of the ejection nozzles are for ejecting build material. That is, the number of nozzles ejecting build material is the same as the number of nozzles ejecting support material. In the representative example shown in FIG. 1A , four print heads 16 a, 16 b, 16 c, and 16 d are shown. Each head 16 a, 16 b, 16 c, and 16 d has a nozzle array. In this example, heads 16 a and 16 b may be for the build material, and heads 16 c and 16 d may be for the support material. In this way, head 16 a may eject one build material, head 16 b may eject another build material, and heads 16 c and 16 d may both eject support material. In alternative embodiments, for example, heads 16 c and 16 d may be combined into a single head with two nozzle arrays for depositing support material. In further alternative embodiments, any one or more print heads may have two or more nozzle arrays for depositing two or more materials, such as two nozzle arrays for two different build materials, or one build material and one support material, with each formulation being deposited through a different array or different number of nozzles.

[0055] It should be understood, however, that this is not intended to limit the scope of the present invention, and that the number of print heads (build heads) for the build material and the number of print heads (support heads) for the support material may vary. Generally, the number of nozzle arrays discharging the build material, the number of nozzle arrays discharging the support material, and the number of nozzles in each array are selected to provide a predetermined ratio a between the maximum discharging velocity of the support material and the maximum discharging velocity of the build material. The value of the predetermined ratio a is preferably selected so that the height of the build material and the height of the support material are equal in each layer formed. Typical values of a are from about 0.6 to about 1.5.

[0056] As used throughout this specification, the term "about" refers to ±10%.

[0057] For example, when a=1, the total dispensing rate of the support material is approximately equal to the total dispensing rate of the build material when all nozzles in the nozzle array are operational.

[0058] For example, apparatus 114 may include M build heads, each with m arrays of p nozzles, and S support heads, each with s arrays of q nozzles, where M×m×p = S×s×q. Each of the M×m build arrays and S×s support arrays may be fabricated as a separate physical unit, which may be assembled and disassembled from multiple arrays. In this embodiment, each such array optionally and preferably includes a respective temperature control unit and material level sensor, and receives an individually controlled voltage for its operation.

[0059] The apparatus 114 further includes a solidification device 324, which may include any device configured to emit light, heat, or the like that may solidify the deposited material. For example, the solidification device 324 may include one or more radiation sources, which may be, for example, ultraviolet, visible, or infrared lamps, or other electromagnetic radiation sources, or electron beam sources, depending on the build material used. In some embodiments of the present invention, the solidification device 324 functions to harden or solidify the build material.

[0060] In addition to solidification device 324, device 114 optionally and preferably includes an additional radiation source 328 for evaporating the solvent. Radiation source 328 optionally and preferably generates infrared light. In some embodiments of the invention, solidification device 324 includes a radiation source that generates ultraviolet light, and radiation source 328 generates infrared light.

[0061] In some embodiments of the present invention, the device 114 includes a cooling device 134, such as one or more fans.

[0062] The print head and radiation source are preferably mounted on a frame or block 128. Preferably, the block 128 is mounted above a tray 360, which serves as a work surface. At least one of the block 128 and the tray 360 is adapted to move back and forth so that the tray 360 and the block 128 establish a relative reciprocating motion. In some embodiments of the present invention, the radiation source is mounted on the block and is adapted to follow the trajectory of the dispensing head to at least partially cure or solidify the material just dispensed by the print head. The tray 360 is positioned horizontally. Following common practice, an XYZ Cartesian coordinate system is selected such that the XY plane is parallel to the tray 360. The tray 360 is preferably configured to move vertically (along the Z direction), typically downward. In various embodiments of the present invention, the apparatus 114 further comprises a leveling device 32, which may comprise a roller and, optionally and preferably, a blade. The leveling device 32 functions to straighten, flatten, and / or define the thickness of a newly formed layer before a subsequent layer is formed thereon. The leveling apparatus 32 preferably includes a waste collection apparatus 136 for collecting excess material generated during leveling. The waste collection apparatus 136 may include a mechanism for delivering material to a waste tank or waste cartridge, as will be described in further detail below.

[0063] In use, the print heads of the units 16 move in a scanning direction, referred to herein as the X direction, selectively dispensing build material in a predetermined configuration as they pass over the tray 360. The build material typically includes one or more support materials and one or more build materials. The print heads' passage is followed by curing of the build material by the radiation source 126. Additional build material may be dispensed in a predetermined configuration during the head's reverse movement back to the starting point of the deposited layer. The layer thus formed can be leveled by a leveling device 32 during the print head's forward or reverse movement, preferably along the path of the print head during the forward and / or reverse movement. After the print heads return to their starting points along the X direction, the print heads can be moved to another position along an indexing direction, referred to herein as the Y direction, and continue building the same layer by reciprocating along the X direction. Alternatively, the print heads may move in the Y direction between forward and reverse movements, or after two or more forward-reverse movements. The series of scans performed by the printhead to complete a single layer is referred to herein as a single scan cycle.

[0064] Once that layer is complete, the tray 360 is lowered in the Z direction to a predetermined Z level depending on the desired thickness of the next printed layer. This procedure is repeated to build the three-dimensional object 112 layer by layer.

[0065] In another embodiment, the tray 360 may be displaced in the Z direction within the layer between the forward and reverse passes of the print head of the unit 16. Such Z displacement is performed to bring the leveling device into contact with the surface in one direction and out of contact in the opposite direction.

[0066] System 110 optionally and preferably includes a build material supply system 330 that includes build material containers or cartridges and supplies a plurality of build materials to manufacturing device 114 .

[0067] A computerized controller 20 controls the manufacturing equipment 114 and, optionally and preferably, also the supply system 330. The controller 20 typically includes electronic circuitry configured to perform control operations. The controller 20 preferably communicates with a data processor 24, which transmits digital data relating to fabrication instructions based on computer object data, such as a CAD configuration represented on a computer-readable medium in a format such as Standard Tessellation Language (STL) format. Typically, the controller 20 controls the voltage applied to each print head or each nozzle array and the temperature of the build material at each print head or each nozzle array.

[0068] Once the manufacturing data is loaded into the controller 20, the controller can operate without user intervention. In some embodiments, the controller 20 receives additional input from an operator, for example, using the data processor 24 or using a user interface 116 in communication with the controller 20. The user interface 116 may be of any type known in the art, such as, for example, but not limited to, a keyboard, a touch screen, etc. For example, the controller 20 may receive as additional input one or more build material types and / or attributes, such as, for example, but not limited to, color, characteristic distortion and / or transition temperature, viscosity, electrical properties, magnetic properties, etc. Other attributes and groups of attributes are also contemplated.

[0069] Another representative, non-limiting example of a system 10 suitable for AM of an object according to some embodiments of the present invention is shown in Figures 1B-1D, which show a top view (Figure 1B), a side view (Figure 1C), and an isometric view (Figure 1D) of the system 10.

[0070] In this embodiment, system 10 includes a tray 12 and a plurality of inkjet print heads 16, each having one or more nozzle arrays with one or more separated nozzles. Material used for three-dimensional printing is supplied to head 16 by a build material supply system 42. Tray 12 may be disk-shaped or annular. Non-circular shapes are also contemplated, provided they are rotatable about a vertical axis.

[0071] The tray 12 and head 16 are optionally and preferably mounted to allow relative rotational movement between the tray 12 and head 16. This can be achieved by (i) a configuration in which the tray 12 rotates relative to the head 16 about a vertical axis 14; (ii) a configuration in which the head 16 rotates relative to the tray 12 about a vertical axis 14; or (iii) a configuration in which both the tray 12 and the head 16 rotate about a vertical axis 14, but at different rotational speeds (e.g., in opposite directions). Below, several embodiments of the system 10 are described with particular emphasis on configuration (i), in which the tray is a rotating tray configured to rotate relative to the head 16 about a vertical axis 14, but it should be understood that the present application also contemplates configurations (ii) and (iii) for the system 10. Any of the embodiments of the system 10 described herein can be adapted to apply to either configuration (ii) or configuration (iii), and one of ordinary skill in the art would know how to make such adjustments given the details provided herein.

[0072] In the following description, the direction parallel to the tray 12 and outward from the axis 14 will be referred to as the radial direction r, the direction parallel to the tray 12 and perpendicular to the radial direction r will be referred to herein as the azimuthal direction φ, and the direction perpendicular to the tray 12 will be referred to herein as the vertical direction z.

[0073] The radial direction r of system 110 defines an index direction y of system 110, and the azimuthal direction φ defines a scan direction x of system 110. Thus, the radial direction is referred to herein interchangeably as the index direction, and the azimuthal direction is referred to herein interchangeably as the scan direction.

[0074] As used herein, the term "radial position" refers to a position on or above tray 12 that is a particular distance from axis 14. When the term is used in reference to a print head, the term refers to a position of the head that is a particular distance from axis 14. When the term is used in reference to a point on tray 12, the term corresponds to any point belonging to a locus of points that forms a circle whose radius is a particular distance from axis 14 and whose center is on axis 14.

[0075] As used herein, the term "azimuthal position" refers to a position on or above tray 12 that is at a particular azimuthal angle relative to a given reference point. A radial position, therefore, refers to any point belonging to a linear locus of points that is at a particular azimuthal angle relative to a reference point.

[0076] As used herein, the term "vertical position" refers to a position on a plane that intersects the vertical axis 14 at a particular point.

[0077] Tray 12 serves as a build platform for three-dimensional printing. The work area, on which one or more objects are printed, is typically, but not necessarily, smaller than the total area of tray 12. In some embodiments of the present invention, the work area is annular. The work area is indicated by the reference numeral 26. In some embodiments of the present invention, tray 12 rotates continuously in the same direction during the formation of an object; in some embodiments of the present invention, the tray reverses its direction of rotation (e.g., oscillates) at least once during the formation of an object. Tray 12 is optionally and preferably removable. Removal of tray 12 can be performed for maintenance of system 10 or, if desired, to replace the tray before printing a new object. In some embodiments of the present invention, system 10 is provided with one or more different replacement trays (e.g., a kit of replacement trays), with two or more trays selected for different types of objects (e.g., different weights), different modes of operation (e.g., different rotational speeds), etc. Tray 12 replacement can be manual or automatic, as desired. When automatic exchange is used, system 10 includes a tray exchanger 36 configured to remove tray 12 from its position under head 16 and replace it with a replacement tray (not shown). In the representative view of Figure 1B, tray exchanger 36 is shown as a drive unit 38 having a movable arm 40 configured to pull tray 12, although other types of tray exchangers are contemplated.

[0078] 2A-2C show exemplary embodiments of print head 16. These embodiments may be used in any of the AM systems described above, including but not limited to system 110 and system 10.

[0079] 2A-2B show print heads 16 having one (FIG. 2A) and two (FIG. 2B) nozzle arrays 22. The nozzles in the arrays are preferably arranged linearly along a straight line. In embodiments where a particular print head has two or more linear nozzle arrays, the nozzle arrays may optionally and preferably be parallel to one another. When a print head has two or more nozzle arrays (e.g., FIG. 2B), all arrays on that head may be supplied with the same build material, or at least two arrays on the same head may be supplied with different build materials.

[0080] When a system similar to system 110 is used, all print heads 16 are optionally and preferably oriented along an index direction and their positions along the scan direction are offset from one another.

[0081] When a system similar to system 10 is used, all print heads 16 are optionally and preferably oriented radially (parallel to the radial direction) and are azimuthal offset from one another. Thus, in these embodiments, the nozzle arrays of different print heads are not parallel to one another, but rather are at an angle to one another, the angle being approximately equal to the azimuthal offset between the respective heads. For example, one head can be oriented radially and positioned at an azimuthal position φ1, while another head can be oriented radially and positioned at an azimuthal position φ2. In this example, the azimuthal offset between the two heads is φ1-φ2, and the angle between the linear nozzle arrays of the two heads is also φ1-φ2.

[0082] In some embodiments, two or more printheads can be combined into a printhead block, where the printheads in the block are generally parallel to one another. A block containing several inkjet printheads 16a, 16b, 16c is shown in Figure 2C.

[0083] In some embodiments, system 10 includes a stabilizing structure 30 positioned below head 16, with tray 12 between stabilizing structure 30 and head 16. Stabilizing structure 30 can function to prevent or reduce vibrations of tray 12 that may occur when inkjet print head 16 is operated. In configurations in which print head 16 rotates about axis 14, stabilizing structure 30 also preferably rotates so that stabilizing structure 30 is always directly below head 16 (with tray 12 between head 16 and tray 12).

[0084] Tray 12 and / or print head 16 are optionally and preferably configured to move parallel to vertical axis 14 along vertical direction z, allowing the vertical distance between tray 12 and print head 16 to be changed. In configurations in which the vertical distance is changed by moving tray 12 along the vertical direction, stabilizing structure 30 also preferably moves vertically with tray 12. In configurations in which the vertical position of tray 12 remains fixed and the vertical distance along the vertical direction is changed by head 16, stabilizing structure 30 is also held in a fixed vertical position.

[0085] Vertical movement can be achieved by vertical drive 28. Once a layer is completed, the vertical distance between tray 12 and head 16 can be increased (e.g., tray 12 can be lowered relative to head 16) by a predetermined vertical distance depending on the desired thickness of the next layer to be printed. This procedure is repeated to build the three-dimensional object layer by layer.

[0086] The operation of inkjet print head 16, and optionally and preferably the operation of one or more other components of system 10, such as movement of tray 12, is controlled by a computerized controller 20. The controller may include electronic circuitry and a non-volatile storage medium readable by the circuitry that stores program instructions that, when read by the circuitry, cause the circuitry to perform control operations as described in further detail below.

[0087] The controller 20 can also communicate with a host computer 24, which transmits digital data related to fabrication instructions based on the computer object data. The digital data may be, for example, Standard Tessellation Language (STL) or Stereolithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY), or any other format suitable for computer-aided design (CAD). The object data format is typically organized according to a Cartesian coordinate system. In such cases, the computer 24 preferably performs a procedure for converting the coordinates of each slice in the computer object data from the Cartesian coordinate system to a polar coordinate system. The computer 24 optionally and preferably transmits the fabrication instructions in the transformed coordinate system. Alternatively, the computer 24 can transmit the fabrication instructions in the original coordinate system provided by the computer object data. In that case, the coordinate conversion is performed by circuitry in the controller 20. The controller 20 can also communicate with the user interface 116, described in detail above.

[0088] Coordinate transformation enables three-dimensional printing on a rotating tray. In non-rotating systems with a fixed tray, the print head typically moves back and forth along a straight line above the fixed tray. In such systems, if the head's ejection velocity is uniform, the print resolution is the same at any point on the tray. Unlike non-rotating systems, in system 10, not all nozzles at the head point to cover the same distance on tray 12 in the same amount of time. Coordinate transformation is optionally and preferably performed to ensure equal amounts of excess material at different radial locations. A representative example of coordinate transformation according to some embodiments of the present invention is shown in Figures 3A-3B, which represent three slices of an object (each slice corresponding to a fabrication command for a different layer of the object), where Figure 3A shows the slice in a Cartesian coordinate system and Figure 3B shows the same slice after applying the coordinate transformation procedure to each slice.

[0089] Generally, controller 20 controls the voltages applied to each component of system 10 based on manufacturing instructions and based on stored program instructions described below.

[0090] Generally, controller 20 controls print head 16 to eject droplets of build material in layers to print a three-dimensional object on tray 12 while tray 12 rotates.

[0091] System 10 optionally and preferably includes one or more radiation sources 18, which may be, for example, ultraviolet, visible, or infrared lamps, or other electromagnetic radiation sources, or electron beam sources, depending on the build material being used. Radiation sources may include any type of radiation emitting device, including, but not limited to, light emitting diodes (LEDs), digital light processing (DLP) systems, resistive heat lamps, etc. Radiation sources 18 serve to harden or solidify the build material. In various exemplary embodiments of the invention, operation of radiation sources 18 is controlled by controller 20, which activates and deactivates radiation sources 18 and, optionally, controls the amount of radiation generated by radiation sources 18.

[0092] In some embodiments of the present invention, system 10 further comprises a leveling device 32, which may optionally and preferably comprise a roller having a blade, and optionally also a waste collection device (not shown, see FIG. 1A), as described in more detail below. Leveling device 32 serves to straighten a newly formed layer before forming a subsequent layer thereon.

[0093] In some optional embodiments, the leveling device 32 has the shape of a conical roller, positioned so that its axis of symmetry 34 is inclined relative to the surface of the tray 12 and its surface is parallel to the tray surface. This embodiment is shown in a side view of the system 10 (FIG. 1C). The conical roller can have the shape of a cone or a truncated cone.

[0094] The operation of the leveling device 32 is optionally and preferably controlled by a controller 20, which can activate and deactivate the leveling device 32. In some optional embodiments, the controller 20 controls the position of the leveling device 32 along a vertical direction (parallel to the axis 14) and / or a radial direction (parallel to the tray 12, toward or away from the axis 14).

[0095] In some embodiments of the invention, print head 16 is configured to move reciprocally relative to the tray along a radial direction r. These embodiments are useful when the length of nozzle array 22 of head 16 is less than the radial width of working area 26 on tray 12. Movement of head 16 in the radial direction is optionally and preferably controlled by controller 20.

[0096] Some embodiments contemplate creating an object by ejecting different materials from different nozzle arrays (belonging to the same or different printheads). These embodiments provide, among other things, the ability to select materials from a predetermined number of materials and define a desired combination of the selected materials and their properties. According to these embodiments, the spatial locations at which each material is deposited in a layer are defined either by having different materials occupy different three-dimensional spatial locations, or by placing two or more different materials at substantially the same three-dimensional location or adjacent three-dimensional locations and spatially intermixing the materials within the layer after deposition, thereby forming a composite material at each location or locations.

[0097] Any combination or mixing of build materials after deposition is contemplated. For example, after a particular material is dispensed, it may maintain its original properties. However, if it is dispensed simultaneously with another build material or other dispensed materials, at the same or nearby locations, a composite material may be formed that has one or more properties different from the dispensed materials.

[0098] In some embodiments of the present invention, the system dispenses digital material for at least one of the layers.

[0099] As used herein and in the art, the term "digital material" refers to the combination of two or more materials at the pixel or voxel level, such that pixels or voxels of different materials intersect with one another in a region. Such digital materials can exhibit novel properties that are influenced by the choice of material type and / or the ratio and relative spatial distribution of two or more materials.

[0100] As used herein, a "voxel" of a layer refers to a physical three-dimensional elemental volume within the layer and corresponds to a single pixel in a bitmap describing the layer. The dimensions of a voxel are approximately equal to the dimensions of the area formed by the build material after it has been dispensed, flattened, and solidified at the location corresponding to the individual pixel.

[0101] This embodiment thus allows for the deposition of a wide range of material combinations and enables the creation of objects where different portions may be composed of multiple different material combinations, depending on the properties required to characterize each portion of the object.

[0102] Further details of the principles and operation of an AM system suitable for this embodiment are provided in U.S. Published Patent Application No. 20100191360, the contents of which are incorporated herein by reference.

[0103] The present embodiment includes a service station system, which may be a subsystem in a three-dimensional printing system, such as, but not limited to, system 10 or system 110. The service station system may function to automatically perform servicing operations, including, but not limited to, wiping the print head ejection face (e.g., orifice plate 121) and recovering liquid build material wiped or expelled from the print head ejection face. During printing of a three-dimensional object, a controller (e.g., controller 20) of the three-dimensional printing system typically controls the print head of the printing system to periodically visit the service station of the present embodiment to wipe the ejection face and / or expel build material. Typically, controller 20 moves the print head to a service station position every N ejected layers, where N may be a predetermined number, e.g., from about 10 to about 50.

[0104] 4A and 4B are schematic top views of a three-dimensional printing system including a service station system 400, according to some implementations of the present invention. A more detailed description of the service station system 400 is provided below with reference to FIGS. 5A-6D. In general, the service station system 400 can be used in any three-dimensional printing system that includes one or more printheads having an ejection surface, e.g., an orifice plate with an array of nozzles. In the illustrative illustration of FIG. 4A, the service station system 400 is a subsystem of the printing system 110, and in the illustrative illustration of FIG. 4B, the service station system 400 is a subsystem of the printing system 10.

[0105] In some embodiments of the present invention, a three-dimensional printing system using the service station system 400 also includes a backlight source 390 located on the back surface 410 of the service station system 400. Preferably, operation of the backlight source 390 is controlled by a printing system controller (e.g., controller 20). The backlight source 390 optionally and preferably provides light in the visible range (e.g., wavelengths from about 400 nm to about 700 nm). The light may be monochromatic or polychromatic and may be generated according to any physical principle. Preferably, the light generated by the light source 390 does not cure the build material used in the printing system. For example, if the build material is UV-curable, the light generated by the light source 390 does not include spectral components in the ultraviolet region. Representative examples of types of light sources that can be used as backlight source 390 include, but are not limited to, packaged or unpackaged light emitting diode (LED) die, laser diode (LD), packaged or unpackaged vertical cavity surface emitting laser (VCSEL) die, packaged or unpackaged organic LED (OLED) die, quantum dot (QD) lamps, etc. Backlight source 390 can be used for alignment as further described below.

[0106] 5A-5H are schematic diagrams of a service station 400 according to some embodiments of the present invention, showing an exploded view (FIG. 5A), an upper right oblique view (FIG. 5B), an upper left oblique view (FIG. 5C), cross-sectional views along lines AA and BB in FIG. 5C, respectively (FIGS. 5D and 5E), left and right side views (FIGS. 5F and 5G, respectively), and a top view (FIG. 5H).

[0107] The service station system 400 includes a vat 402 having an open top 412 and a bottom 436, which is optionally and preferably sloped and includes an exit port 438 (best seen in FIGS. 5D-5G). Preferably, but not necessarily, the vat 402 has a quick-release connector 404 on its front 406 and a hinge 408 on its back 410. The hinge 408 connects the open top 412 of the vat 402 to a mounting plate 500 of a three-dimensional printing system (see FIG. 5H), and the connector 404 supports the vat 402 so that the top 412 of the vat 402 is approximately horizontal. In some embodiments, the connector 404 is secured to the same mounting plate 500 as the hinge 408 by a connector holder 405. The mounting plate 500 of the three-dimensional printing system to which the vat 402 is attached is optionally and preferably at the top of the printing system, at a height just below the height of the ejection faces of the print heads.

[0108] The quick release connector 404 may comprise, for example, a latch assembly, or optionally, a snap-type connector. If the connector 404 is a latch assembly, it optionally and preferably comprises a curved, resilient wire, such as, but not limited to, a curved metal wire shaped to support the tub 402 from below, as shown in Figures 5A-5D and 5F-5G. The tub 402 is rotatable about an axis defined by a hinge 408. An advantage of connecting the tub to the printing system on one side by a hinge and supporting the other side with a quick release connector is that it allows maintenance operations to be performed without having to remove the tub 402 from the printing system, as described in more detail below.

[0109] The service station system 400 also includes a wiper assembly 414 having a wiper device 416 configured to wipe one or more print head ejection surfaces (e.g., the orifice plate 121 of the head 16) as the print head reciprocates over the reservoir 402 between the rear surface 410 and the front surface 406.

[0110] The wiper device 416 can be oriented approximately perpendicular to the index direction of the three-dimensional printing system. These embodiments are particularly useful when a rotary system (e.g., system 10) is used. In this case, the head moves along a radial direction (see FIG. 4B) toward the location of the service station 400. Thus, the wiper device 416, oriented generally azimuthally, wipes the discharge face of the head as it enters the service station zone. In embodiments in which the device 416 is perpendicular to the index direction, the width of the wiper device is optionally and preferably at least the width of all print heads in the printing system. This allows the same wiper device 416 to wipe all heads in the printing system.

[0111] Alternatively, the wiper device 416 can be oriented generally parallel to the index direction of the three-dimensional printing system. This embodiment is particularly useful when a linear reciprocating system (e.g., system 110) is used. In this case, the head moves along a scanning direction toward the location of the service station 400 (see FIG. 4A). Thus, the wiper device 416, oriented generally in the index direction, wipes the ejection face of the head as it enters the service station zone. In embodiments in which the device 416 is generally parallel to the index direction, the width of the wiper device is optionally and preferably at least the length of the print head. This allows the same wiper device 416 to wipe the entire nozzle array of the printing system.

[0112] Further optional features of wiper assembly 414 are described below with respect to Figures 6A-6D.

[0113] 5H, during use of the service station system 400, the printing system controller moves the print head over the reservoir 402 in a direction 502 at the location of the service station system 400. The direction 502 may be an indexing direction or a scanning direction. If the printing system is a rotary system, the direction 502 is preferably an indexing direction, and if the printing system is a linear reciprocating system, the direction 502 is preferably a scanning direction.

[0114] During movement of the print head over the reservoir 402, a wiper device 416 engages the head's discharge surface to remove excess build material that may have accumulated thereon. The excess material drips from the wiper device 416 into the reservoir 402 as liquid waste. The liquid waste can be removed from the reservoir 402 via an outlet port 438, for example, by a pump (not shown) or by gravity. While the print head is over the reservoir 402, the controller can also instruct the print head to perform a purge procedure. For example, a purge procedure may be performed to remove previous build material from the head's channels and other fluid passages in the system before replacing the build material container that supplies the head. In this case, the reservoir 402 can also collect the purge material and then discharge it via the outlet port 438.

[0115] In some embodiments of the invention, the service station system 400 also includes a liquid trap 440 that covers the top 412 of the reservoir 402. The liquid trap 440 is preferably perforated. In these embodiments, the printing system controller moves the print head to a position above the liquid trap 440 at the service station system 400, causing liquid waste to drip from the wiper device onto the liquid trap 440 and through the perforations in the trap 440 into the reservoir 416. The liquid trap 440 is useful for the purge procedure described above. In this case, the head purges build material onto the trap 440, which then drips through the perforations in the liquid trap 440 into the reservoir 402.

[0116] The liquid trap 440 has the advantage of allowing drips into the reservoir at predetermined locations determined by the perforations. Another advantage is that it provides a barrier between the bulk of waste liquid in the reservoir and the print head, limiting exposure of the waste liquid to light (e.g., ultraviolet light). The liquid trap 440 can include two or more perforated liquid guide channels 442 for collecting and guiding the liquid build material. The number of channels 442 is preferably equal to the total number of build material channels in the print head of the printing system. For example, the liquid trap 440 can include one channel for each linear array of nozzles. Preferably, the channels 442 are perforated at multiple locations along their length, excluding locations near the wiper assembly 414. This configuration protects various components of the wiper assembly 414 from contamination by liquid waste.

[0117] In some embodiments of the invention, a placement sensor 504 is mounted on the mounting plate 500 of the printing system (see FIG. 5H). The placement sensor 504 can be of any type, including, but not limited to, an electromechanical switch or an optical sensor. The placement sensor 504 includes or is mounted near a slot (not shown) shaped and dimensioned to receive the protrusion 441 of the liquid trap 440 (see FIGS. 5A-5C), and is optionally and preferably configured to generate a signal indicating that the protrusion 441 is positioned in the slot. The signal generated by the sensor 504 is transmitted to a controller of the three-dimensional printing system (e.g., controller 20 of system 10 or system 110). In response to a signal from the sensor 504 indicating that the protrusion 441 is not positioned, the controller can issue a warning that the service station system 400 is not properly mounted and can also terminate the print job (e.g., by disabling all nozzles in the array and terminating relative motion between the print block and the tray).

[0118] Reference is now made to Figures 6A-6D, which are schematic diagrams illustrating wiper assembly 414 in greater detail. Some of the features described below also appear in one or more of Figures 5A-5G. Like reference numbers refer to like features throughout this specification.

[0119] In some embodiments of the invention, wiper assembly 414 includes wiper base 418, and wiper device 416 is removably connected to wiper base 418 by a dedicated connector 420. Connector 420 is optionally and preferably a male-female quick release type, as shown in the disconnected state in Figure 6A (see also Figure 5A above) and the connected state in Figure 6B. An advantage of these embodiments is that wiper device 416 can be easily replaced without removing service station system 400 from the printing system.

[0120] FIG. 6C is a cross-sectional view taken along line AA of FIG. 6B, but additionally showing a shaft 422 to which the wiper base 418 is attached. The shaft 422 is optionally and preferably a rotatable shaft 422. The shaft 422 is best seen in FIG. 6D, which also shows a motor 424 that rotates the shaft 422. The motor 424 is preferably an electric motor, such as a stepper motor. The motor 424 is controllable by a controller (e.g., controller 20) of the three-dimensional printing system. A mechanical transmission 426 is between the motor 424 and the shaft 422. In the illustrated embodiment, the mechanical transmission 426 comprises cogwheels, although other types of transmissions (e.g., belts, tracks, pulleys) are also contemplated. The motor 424 is preferably mounted to a motor support structure 403 that is connectable to, or more preferably, an integral part of, the tub 402 (see, e.g., FIG. 5C). In some embodiments of the invention, motor 424 is attached to three corners of structure 403 with three screws 434, leaving the fourth corner unattached.

[0121] A shaft 422 passes through the tub 402 (not shown in FIGS. 6A-6D; see, e.g., FIGS. 5A and 5B), where the transmission 426 and motor 424 are outside the tub 402, and the wiper base 418 and wiper device 416 are inside, preferably above, the tub 402.

[0122] In some embodiments of the present invention, the wiper base 418 is attached to the axis 422 by a shaft 428 (see also FIG. 5A ). In these embodiments, the shaft 428 is rotatable independently of and perpendicular to the rotation of the axis 422 by the motor 424. The advantage of having the shaft 428 rotatable perpendicular to the axis 422 is that it provides the wiper device 416 with two rotational degrees of freedom, improving the ability to align the wiper device 416 with the printhead discharge face, thereby improving wiping efficiency. The advantage of having the shaft 428 rotatable independently of the axis 422 is that it provides the wiper device 416 with a self-aligning feature. Specifically, by gently pressing the wiper device 416 against the printhead discharge face, the wiper device 416 is aligned with the discharge face by the independent rotation of the shaft 428. Preferably, the shaft 428 is inclined relative to the horizontal, as shown in FIG. 6C (see also FIG. 5D ). This tilt allows the vertical position of wiper device 416 to be adjusted to engage the ejection face of the printhead, for example, by rotating shaft 422 using motor 424 .

[0123] In some embodiments of the present invention, wiper base 418 is shaped as or includes a shielding structure to shield the connection between shaft 428 and axle 422 from liquid build material being wiped by the wiper device or displaced by the print head. The inventors have found that this shielding structure reduces mis-rotation of shaft 428 relative to axle 422.

[0124] The wiper device 416 typically includes a wiping element 430 that engages the printhead discharge surface during wiping. The wiping element 430 preferably has a substantially straight, continuous wiping edge across its entire width, as shown in Figures 6A, 6B, and 6D. Preferably, the wiping element 430 is elastomeric. Suitable elastomers for the wiping element 430 are those characterized by a Shore A hardness of about 70 to about 90.

[0125] Shore A hardness, also referred to as Shore hardness or simply hardness, describes a material's resistance to permanent indentation as defined on the durometer scale, Type A. Shore hardness is typically determined according to ASTM D2240.

[0126] Representative types of elastomers suitable for this embodiment include, but are not limited to, rubbers such as ethylene propylene diene.

[0127] In some embodiments of the present invention, wiping element 430 (e.g., an elastomeric wiping element) is connected to a resilient, non-polymeric planar structure 432, such as, but not limited to, a metallic planar structure. Structure 432 adds an additional degree of flexibility to the previously described self-aligning property of wiper device 416, as resilient forces can realign wiping element 430 with the discharge surface of the head if temporary misalignment occurs, for example, due to excessive buildup of material on the head. Structure 432 also extends the life of wiping element 430, by maintaining sufficient pressure on the head for element 430, even as the element approaches wear.

[0128] 6D , in some embodiments of the invention, the wiper assembly 414 includes a flag member 450 mounted on the end of the shaft 422 opposite the mechanical transmission 426. In these embodiments, the service station system 400 includes a position sensor 452 mounted on the shaft 422 directly above the end of the flag member 450. When the flag member passes over a sensing element of the position sensor 452, the sensor 452 sends a signal to a printing system controller (e.g., controller 20). The controller can use the signal as an indication of the angle of the shaft 422 and, therefore, the vertical position of the wiper device 416 mounted thereon. For example, the flag member 450 can be mounted on the shaft 422 so that when the flag member 450 is in its highest position, the wiper is low in the tub 402. During adjustment of the vertical position of the wiper device 416 by the motor 424, the flag member 450 rotates downward. Thus, in this case, a signal from sensor 452 indicates that a calibration procedure is about to be performed, and the controller can issue a warning or terminate the print job in response to such a signal.

[0129] Reference is now made to Figure 7, which is a flow diagram illustrating a method suitable for positioning a wiper device in a three dimensional printing system, according to some embodiments of the present invention. This method can be performed using, for example, service station system 400 and either of three dimensional printing systems 10 and 110.

[0130] Unless otherwise specified, it should be understood that the operations described below can be performed either simultaneously or sequentially in many combinations or orders of execution. In particular, the order of the flow diagrams should not be considered limiting. For example, two or more operations that appear in a particular order in the following description or flow diagrams may be performed in a different order (e.g., in the reverse order) or substantially simultaneously. Furthermore, some operations described below are optional and may not be performed.

[0131] The method begins at 700 and continues at 701 with a print head of a printing system being moved into position above a wiper device (e.g., wiper device 416) of a service station system. At 702, the print head and wiper device are illuminated from behind by a backlight source (e.g., backlight source 390, see FIGS. 4A and 4B) such that light from the backlight source passes between the head and the wiper device.

[0132] At 703, the vertical distance between the wiper device and the print head is decreased. This can be done by activating a motor (e.g., motor 424) of the service station system. Operation 703 may begin before operation 702. For example, in some embodiments of the present invention, the controller automatically activates the backlight source when the motor rotates the service station shaft. Operation 703 preferably continues until the wiper device blocks light from the backlight source such that the light from the backlight source is no longer visible to a user when viewing service station system 400 from front 406. When the light from the backlight source is blocked, the method can determine that the wiper device has engaged the discharge face of the print head and terminate the decrease in distance.

[0133] In some embodiments of the invention, the method continues to 704 where the vertical distance is increased by a predetermined amount to reduce the stress that the print head exerts on the wiping element of the wiper device, the predetermined amount being typically less than 1 mm, or less than 0.5 mm.

[0134] The method ends at 705.

[0135] As used herein, the term "about" refers to ±10%.

[0136] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features of other embodiments.

[0137] The term "optionally" is used herein to mean "provided in some embodiments and not provided in other embodiments." Any particular embodiment of the present invention may include multiple "optional" features unless such features are contradictory.

[0138] The terms "comprises," "comprised," "includes," "including," "having," and their conjugations mean "including but not limited to."

[0139] The term "consisting of" means "including and limited to."

[0140] The term "consisting essentially of" means that a composition, method, or structure may include additional ingredients, steps, and / or components, but only if the additional ingredients, steps, and / or components do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0141] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" can encompass multiple compounds, including mixtures thereof.

[0142] Throughout this application, various embodiments of the present invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as a fixed limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all possible subranges along with individual numerical values within that range. For example, a description of a range such as 1 to 6 should be considered to have specifically disclosed subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numerical values within that range, e.g., 1, 2, 3, 4, 5, and 6. This applies regardless of the broadness of the range.

[0143] Whenever a range of numerical values is given herein, it is meant to include any recited number (fractional or integer) within the stated range. The phrases "ranging between" a first specified number and a second specified number and "ranging from" a first specified number "to" a second specified number are used interchangeably herein and are meant to include the first specified number and the second specified number, and all fractional and integer numbers therebetween.

[0144] It is understood that certain features of the invention, which are for clarity described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are for brevity described in the context of a single embodiment may also be provided separately or in any suitable subcombination, or as appropriate to any other described embodiment of the invention. Certain features described in the context of various embodiments should not be considered essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0145] While the present invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

[0146] All publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entirety to the same extent as if each individual publication, patent, and patent application was specifically and individually indicated to be incorporated herein by reference. Furthermore, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent used as section headings, they shall not necessarily be construed as limiting. Additionally, any priority documents of this application are incorporated herein by reference in their entirety.

Claims

1. 1. A service station system for a three dimensional printing system having at least one print head, comprising: a vat having a quick release connector on a front side and a hinge on a rear side, the open top side of the vat being hinged to a surface of the three dimensional printing system; a wiper assembly including a wiper device removably connected to a wiper base mounted on a rotatable shaft that passes through the reservoir, the wiper device configured to wipe the discharge face of the print head as the print head reciprocates over the reservoir between the rear face and the front face; a motor that rotates the shaft; A system comprising:

2. 2. The system of claim 1, wherein the wiper assembly comprises a shaft, the wiper base is attached to the rotatable axle by the shaft, and the shaft is rotatable independently of and perpendicular to rotation of the axle by the motor.

3. 1. A service station system for a three dimensional printing system having at least one print head, comprising: a vessel having a front surface, a back surface, and an open top surface; a wiper assembly having a wiper device and a wiper base removably connected to the wiper device and mounted by a shaft on a rotatable shaft passing through the tub, the wiper device configured to wipe the discharge face of the print head as the print head reciprocates over the tub between the rear face and the front face; a motor that rotates the shaft; Equipped with A system in which the shaft is rotatable independently of and perpendicular to the rotation of the axis by the motor.

4. 4. The system of claim 2 or claim 3, wherein the shaft is inclined relative to the horizontal.

5. 5. The system of claim 2, wherein the wiper assembly includes a shielding structure for shielding the connection between the shaft and the axis from liquid build material wiped by the wiper device or displaced by the print head.

6. 6. The system of claim 1, further comprising a liquid trap covering the upper surface and having a plurality of perforated liquid guide channels for collecting liquid build material wiped by the wiper device or expelled by the print head.

7. 1. A service station system for a three dimensional printing system having at least one print head, comprising: a vessel having a front surface, a back surface, and an open top surface; a wiper assembly having a wiper device configured to wipe a discharge face of the print head as the print head reciprocates over the reservoir between the rear face and the front face; a liquid trap covering the upper surface and having a plurality of liquid-guiding channels for collecting liquid build material wiped by the wiper device or expelled by the print head; Equipped with Each of the liquid-guiding channels of the liquid trap is perforated at multiple locations along its length.

8. 8. The system of claim 6 or claim 7, wherein the number of grooves is equal to the number of build material channels of the at least one print head.

9. 8. The system of claim 7, wherein the plurality of locations is a plurality of locations along the length, excluding a location near the wiper assembly.

10. The system of any one of claims 1 to 9, wherein the wiper device is oriented substantially perpendicular to an index direction of the three dimensional printing system.

11. The system of claim 10 , wherein the width of the wiper device is at least the width of all print heads of the three dimensional printing system.

12. The system of any one of claims 1 to 8, wherein the wiper device is oriented parallel to an index direction of the three dimensional printing system.

13. The system of claim 10, wherein the width of the wiper device is at least the length of the printhead.

14. A system according to any one of claims 1 to 13, wherein the wiper device comprises an elastomeric wiping element that is substantially straight and has a wiping edge that is continuous across its width.

15. The system according to any one of the preceding claims, wherein the wiper device comprises an elastomeric wiping element characterized by a hardness of 70 to 90 Shore A.

16. The system of claim 15 , wherein the elastomeric wiping element comprises a synthetic rubber.

17. 17. The system of claim 16, wherein the synthetic rubber comprises ethylene propylene diene.

18. The system of any one of claims 1 to 17, wherein the wiper device comprises an elastomeric wiping element connected to a resilient non-polymeric planar structure.

19. 20. The system of claim 18, wherein the resilient non-polymeric planar structure is metal.

20. The system of claim 1 or claim 2, wherein the quick release connector comprises a latch assembly.

21. 21. The system of claim 20, wherein the latch assembly comprises a curved, resilient wire shaped to support the vessel from below.

22. 1. A system for three dimensional printing, comprising: at least one print head for dispensing build material; The service station system according to any one of claims 1 to 21; A system comprising:

23. 23. The system of claim 22, further comprising a computerized controller configured to control at least one print head to periodically visit the service station system to wipe the ejection surface and / or expel build material into the reservoir.

24. 1. A three dimensional printing system, comprising: at least one print head for dispensing build material; a service station system having a motor; A backlight source; a computerized controller configured to control the print head and the service station system; Equipped with The service station system includes: (a) a vessel having a front surface and a back surface; (b) a wiper assembly including a wiper device removably connected to a wiper base mounted on a rotatable shaft that passes through the reservoir, the wiper device configured to wipe the discharge face of the print head as the print head reciprocates between the rear and front faces of the reservoir; (c) a motor for rotating the shaft; Equipped with The backlight source is positioned behind the tank, and when the wiper device disengages from the ejection surface, light from the backlight source passes between the wiper device and the ejection surface, and when the wiper device engages with the ejection surface, the light from the backlight source is blocked by the wiper device.

25. 25. The three dimensional printing system of claim 24, wherein the computerized controller is configured to automatically activate the backlight source when the motor rotates the shaft.

26. 1. A method for printing a three-dimensional object, comprising: receiving three-dimensional printing data corresponding to the shape of the object; Providing data to the three dimensional printing system of any one of claims 22 to 25; periodically moving the at least one print head to visit the service station system to wipe the ejection surface and / or empty build material into the reservoir; A method comprising:

27. 1. A method for aligning a wiper device in a three dimensional printing system having at least one print head and a wiper device, comprising: moving the print head to a position above the wiper device; back-illuminating the print head and the wiper device so that light passes therebetween; decreasing the vertical distance between the wiper device and the print head until the wiper device blocks the light; The method includes:

28. 28. The method of claim 27, wherein the wiper device comprises an elastomeric wiping element, the method including increasing the vertical distance to reduce stress exerted by the print head on the elastomeric wiping element when the wiper device blocks light.

29. 10. A method for performing maintenance on a three dimensional printing system, the three dimensional printing system comprising the service station system of claim 1 or claim 2, the method comprising: releasing the quick release connector to hinge the front surface of the tub downward to expose a wiper base; removing the wiper device from the wiper base; removably connecting a replacement wiper device to the wiper base; The method includes:

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