Stereolithography apparatus

Abstract

A three-dimensional object printing device that prints a three-dimensional work of various shapes in a wide range. The three-dimensional object printing device has a photographing device fixed to a base and photographing an object inside a photographing range, a first robot arm that supports a head having a nozzle that ejects a liquid and changes a position and an attitude of the head, and a second robot arm that supports a three-dimensional work and changes a position and an attitude of the work, and in the three-dimensional object printing device, a material supply step in which the second robot arm moves the work from outside to inside of the photographing range, and a printing step in which the head ejects the liquid to the work while at least one of the first robot arm and the second robot arm relatively moves the head and the work inside the photographing range are executed.

Description

TECHNICAL FIELD

[0001] The present application relates to a three-dimensional object printing device. BACKGROUND

[0002] A three-dimensional object printing device that performs printing on the surface of a three-dimensional work by an inkjet method is known. For example, in Patent Literature 1, a printing device that performs printing while changing the relative position of a printed object and a print head using a multi-joint robot arm is described.

[0003] In the printing device described in Patent Literature 1, since the position and posture of the printed object become a state where they are fixed, there are regions where the print head cannot be brought close to the printed object by only the movement of the multi-joint robot arm depending on the shape and the like of the printed object. Therefore, in the printing device described in Patent Literature 1, there is a problem that printing cannot be appropriately performed with respect to three-dimensional printed objects of various shapes.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2017-19183 SUMMARY

[0005] In order to solve the above problems, one embodiment of the three-dimensional object printing device according to the present application is a three-dimensional object printing device that performs printing on a three-dimensional work, including: a photographing device that is fixed to a base and photographs an object located inside a photographing range; a first robot arm that supports a head having a nozzle that ejects a liquid and changes the position and posture of the head; and a second robot arm that supports the work and changes the position and posture of the work, wherein the following steps are performed: a material supply step in which the second robot arm moves the work from outside the photographing range to inside the photographing range; and a printing step in which the head ejects the liquid to the work while at least one of the first robot arm and the second robot arm relatively moves the head and the work inside the photographing range. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 A perspective view showing an outline of the three-dimensional object printing device according to the first embodiment.

[0007] Figure 2 A block diagram showing an electrical structure of the three-dimensional object printing device according to the first embodiment.

[0008] Figure 3 A perspective view of the first robot arm.

[0009] Figure 4 A perspective view showing an outline structure of the liquid ejection unit.

[0010] Figure 5 A plan view of a three-dimensional object printing apparatus according to a first embodiment.

[0011] Figure 6 A flowchart showing a flow of actions of a three-dimensional object printing apparatus according to the first embodiment.

[0012] Figure 7 A diagram for explaining a material supply step.

[0013] Figure 8 A diagram for explaining an action of a first robot in a first printing step.

[0014] Figure 9 A diagram for explaining a printing region of a workpiece in the first printing step.

[0015] Figure 10 A diagram for explaining an avoidance step.

[0016] Figure 11 A diagram for explaining a movement step.

[0017] Figure 12 A diagram for explaining a hardening step and a maintenance step.

[0018] Figure 13 A diagram for explaining a material removal step.

[0019] Figure 14 A flowchart showing a flow of actions of a three-dimensional object printing apparatus according to a second embodiment.

[0020] Figure 15 A flowchart showing a flow of actions of a three-dimensional object printing apparatus according to a modification 1.

[0021] Figure 16 A plan view of a three-dimensional object printing apparatus according to the modification 1. DETAILED DESCRIPTION

[0022] Hereinafter, a preferred embodiment according to the present application will be described with reference to the accompanying drawings. In each drawing, the size or scale of each part is appropriately different from the actual situation, and parts shown schematically for easy understanding are also included. Furthermore, in the following description, the scope of the present application is not limited to these modes unless the present application is particularly limited in the description.

[0023] The following description is appropriately made using mutually intersecting X, Y, and Z axes. Furthermore, one direction along the X axis is referred to as an X1 direction, and a direction opposite to the X1 direction is referred to as an X2 direction. Likewise, directions opposite to each other along the Y axis are referred to as a Y1 direction and a Y2 direction. Furthermore, directions opposite to each other along the Z axis are referred to as a Z1 direction and a Z2 direction.

[0024] Here, the X, Y, and Z axes are coordinate axes of a general coordinate system set in a space in which the first robot arm 3 and the second robot arm 4 described later are provided. Typically, the Z axis is an upright axis, and the Z2 direction corresponds to a downward direction in the upright direction. A base coordinate system with reference to the base of each of the first robot arm 3 and the second robot arm 4 is brought into correspondence with this general coordinate system through calibration. In the following, for the sake of convenience, a case in which the general coordinate system is used as a robot arm coordinate system to control the movement of each of the first robot arm 3 and the second robot arm 4 is exemplified.

[0025] In addition, the Z axis can also not be an upright axis. Furthermore, although the X, Y, and Z axes are typically orthogonal to each other, they are not limited thereto, and there are cases in which they are not orthogonal. For example, the X, Y, and Z axes only need to intersect each other at an angle within a range of 80° or more and 100° or less.

[0026] 1. First Embodiment

[0027] 1-1. Overview of Stereoscopic Object Printing Apparatus

[0028] Figure 1 is a stereogram showing an overview of a stereoscopic object printing apparatus 1 according to the first embodiment. The stereoscopic object printing apparatus 1 is an apparatus that uses the first robot arm 3 and the second robot arm 4 and performs printing on the surface of a stereoscopic workpiece W by an inkjet method.

[0029] In Figure 1 the example shown, the workpiece W is a rugby ball in an ellipsoidal shape. In addition, the shape or size or the like of the workpiece W is not limited to Figure 1 the example shown, but is an arbitrary shape.

[0030] As Figure 1 shown, the stereoscopic object printing apparatus 1 has a base 2, a first robot arm 3, a second robot arm 4, a liquid ejection unit 5, an ink supply unit 6, a photographing unit 7, a maintenance unit 8, a placement portion 9, a hardening unit 10, a controller 11, a control module 12, and a computer 13. In the following, first, each portion of the stereoscopic object printing apparatus 1 shown in Figure 1 will be simply described in order.

[0031] The base 2 is a table having a surface 2a that supports the first robot arm 3 and the second robot arm 4. The surface 2a is a surface facing the Z1 direction. In the present embodiment, the surface 2a supports not only the first robot arm 3 and the second robot arm 4 but also the ink supply unit 6, the imaging unit 7, the maintenance unit 8, the placement section 9, and the hardening unit 10. Here, each of the first robot arm 3, the second robot arm 4, the ink supply unit 6, the imaging unit 7, the maintenance unit 8, the placement section 9, and the hardening unit 10 is fixed to the base 2 directly or indirectly via other components by screw fastening or the like.

[0032] In Figure 1 the illustrated example, the base 2 is box-shaped, and the controller 11 and the control module 12 are housed inside the base 2. Further, an exhaust port 2b is provided on the surface 2a of the base 2. An exhaust mechanism, not shown, is connected to the exhaust port 2b. The exhaust mechanism sucks gas on the surface 2a from the exhaust port 2b and discharges the sucked gas to the outside after performing a purification process or the like on the sucked gas.

[0033] Although detailed illustration is omitted, as shown by a double-dotted line in Figure 1 , a housing 20 is disposed at a position in the Z1 direction with respect to the base 2. The housing 20 is a structure that forms a space for housing the first robot arm 3 and the second robot arm 4 and the like structures supported on the base 2 between the surface 2a. The housing 20 has, for example, a plurality of columns and a plurality of beams made of metal or the like, and a plurality of plates such as a ceiling and a wall made of a transparent material such as acrylic resin. Further, on the housing 20, a window for supplying and taking out the workpiece W to the placement section 9 is provided.

[0034] In addition, the structure of the base 2 is not limited to Figure 1 the example illustrated, but is an arbitrary structure. Further, the base 2 need only be provided as necessary, and can be omitted. In this case, each structural element of the three-dimensional object printing apparatus 1 is provided, for example, on a floor, a wall, or a ceiling of a building or the like. In other words, the base 2 can not be a structural element of the three-dimensional object printing apparatus 1, but can be, for example, a floor, a wall, or a ceiling of a building or the like. Although in the present embodiment, each structural element of the three-dimensional object printing apparatus 1 other than the base 2 is supported on the surface 2a as the same plane, each structural element can be supported on a surface facing a different direction. For example, the first robot arm 3 can be provided on one of a floor, a wall, and a ceiling, and the second robot arm 4 can be provided on another of them. Further, the first robot arm 3 can be provided on one of a plurality of walls facing different directions, and the second robot arm 4 can be provided on another of them.

[0035] The first robot arm 3 is a robot arm that changes the position and posture of the liquid discharge unit 5 in the universal coordinate system. In the example shown in the figure, the first robot arm 3 is a so-called six-axis vertical multi-joint robot arm, and at the top end of the arm of the first robot arm 3, the liquid discharge unit 5 is installed as an end effector in a state fixed by screw fastening or the like. In addition, regarding the structure of the first robot arm 3, it will be described later based on the figure. Figure 1 In the example shown in the figure, the first robot arm 3 is a so-called six-axis vertical multi-joint robot arm, and at the top end of the arm of the first robot arm 3, the liquid discharge unit 5 is installed as an end effector in a state fixed by screw fastening or the like. In addition, regarding the structure of the first robot arm 3, it will be described later based on the figure. Figure 3 However, the first robot arm 3 and the second robot arm 4 can be different structures from each other, and in the present embodiment, the arm length or the load-carrying weight or the like is different as needed. In addition, the number of joints of the first robot arm 3 and the second robot arm 4 can be different from each other.

[0036] The liquid discharge unit 5 is a device having a head 5a that discharges ink as an example of "liquid" toward the workpiece W. In the present embodiment, the liquid discharge unit 5 has, in addition to the head 5a, a pressure regulating valve 5b and a pre-hardening light source 5c. In addition, regarding the structure of the liquid discharge unit 5, it will be described later based on the figure. Figure 4 In the example shown in the figure, the first robot arm 3 is a so-called six-axis vertical multi-joint robot arm, and at the top end of the arm of the first robot arm 3, the liquid discharge unit 5 is installed as an end effector in a state fixed by screw fastening or the like. In addition, regarding the structure of the first robot arm 3, it will be described later based on the figure.

[0037] The ink is not particularly limited, and for example, an aqueous ink in which a color material such as a dye or a pigment is dissolved in a water-based solvent, a hardening ink using a hardening resin such as an ultraviolet hardening type, and a solvent-based ink in which a color material such as a dye or a pigment is dissolved in an organic solvent, or the like can be exemplified. Among them, a hardening ink is preferably used. Although the hardening ink is not particularly limited, it can be, for example, any one of a thermal hardening type, a light hardening type, a radiation hardening type, and an electron beam hardening type, but a light hardening type such as an ultraviolet hardening type is preferable. In addition, the ink is not limited to a solution, and can be an ink in which a color material or the like is dispersed as a dispersed substance in a dispersant. Furthermore, the ink is not limited to an ink containing a color material, and for example, can be an ink containing conductive particles such as metal particles for forming a wiring or the like as a dispersed substance, can be a transparent ink, and can be a treatment liquid for performing surface treatment of the workpiece W.

[0038] On the other hand, the second robot arm 4 is a robot arm that changes the position and posture of the workpiece W in the universal coordinate system. In the example shown in the figure, the second robot arm 4 is a six-axis vertical multi-joint robot arm, and at the top end of the arm of the second robot arm 4, the hand mechanism 40 is installed as an end effector in a state fixed by screw fastening or the like. Figure 1 In the example shown in the figure, the first robot arm 3 is a so-called six-axis vertical multi-joint robot arm, and at the top end of the arm of the first robot arm 3, the liquid discharge unit 5 is installed as an end effector in a state fixed by screw fastening or the like. In addition, regarding the structure of the first robot arm 3, it will be described later based on the figure.

[0039] In addition, the second robot arm 4 is constituted similarly to the first robot arm 3 except that the installed end effector is different. However, the first robot arm 3 and the second robot arm 4 can be different structures from each other, and in the present embodiment, the arm length or the load-carrying weight or the like is different as needed. In addition, the number of joints of the first robot arm 3 and the second robot arm 4 can be different from each other.

[0040] The gripper mechanism 40 is a robotic arm gripper that holds the workpiece W in a loading and unloading manner. Here, "holding" encompasses both adsorption and gripping. Figure 1 In the example shown, the gripper mechanism 40 is a mechanism that uses negative pressure to attract the workpiece W. Furthermore, the structure of the gripper mechanism 40 is appropriately determined according to the shape, size, or material of the workpiece W. The gripper mechanism 40 is not limited to an attraction mechanism achieved by negative pressure; for example, it can also be an attraction mechanism achieved by magnetic force, or a gripping gripper mechanism with multiple fingers or claws.

[0041] The ink supply unit 6 is a mechanism for supplying ink to the liquid ejection unit 5. Figure 1 In the example shown, the ink supply unit 6 includes an ink tank 6a, a supply pipe 6b, a secondary tank 6c, and a supply pipe 6d. The ink tank 6a is a container for storing ink and is made of, for example, a flexible film. The supply pipe 6b is a pipe connecting the ink tank 6a and the secondary tank 6c and is made of, for example, a rubber or elastomer material. The secondary tank 6c is a container for storing ink supplied from the ink tank 6a via the supply pipe 6b and is made of, for example, a resin or metal material. Ink can be supplied from the ink tank 6a to the secondary tank 6c, for example, by means of a pump (not shown) located midway through the supply pipe 6b. The supply pipe 6d is a pipe connecting the secondary tank 6c and the liquid ejection unit 5 and is made of, for example, a rubber or elastomer material. By making the supply pipe 6d flexible, changes in the position and orientation of the liquid ejection unit 5 are permitted.

[0042] Here, the auxiliary tank 6c is fixed to the housing 20 at a position higher in the vertical direction than the moving area of ​​the liquid ejection unit 5. Therefore, since the auxiliary tank 6c is always positioned in the Z1 direction relative to the liquid ejection unit 5, ink can be supplied from the auxiliary tank 6c to the liquid ejection unit 5 at a predetermined pressure even without using a pump or similar mechanism. Alternatively, the auxiliary tank 6c can be omitted. In this case, for example, only a pump needs to be used to supply ink from the ink tank 6a to the liquid ejection unit 5 at a predetermined pressure.

[0043] The imaging unit 7 is a device for detecting the position and posture of the workpiece W. The imaging unit 7 has an imaging device 7a and an illumination unit 7b. The imaging device 7a, which is generally called a vision sensor, is a camera including an imaging optical system and an imaging element, and images an object located inside a range of imaging. The imaging optical system is an optical system including at least one imaging lens, and can also include various optical elements such as a prism, and can include a zoom lens or a focus lens. The imaging element is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor. In the imaging device 7a, an imaging coordinate system of two or three axes is set with respect to an arbitrary point of an image. The imaging coordinate system is correlated with the base coordinate system or the general coordinate system described above by calibration. The illumination unit 7b is a light source including a light emitting element such as an LED (light emitting diode), and emits light toward the range of imaging of the imaging device 7a. In the case where the workpiece W is imaged as the object by the illumination by the illumination unit 7b, the contrast of the image of the imaging device 7a can be improved. As a result, the detection accuracy of the position and posture of the workpiece W based on the imaging result of the imaging device 7a can be improved. In the illumination unit 7b, an optical member such as a lens or a reflection plate is appropriately provided for adjusting the direction or range of emission of light. The direction of emission of light of the illumination unit 7b is the Yl direction, and the light emitted from the illumination unit 7b spreads in the X direction and the Z direction as it approaches the Yl direction from the illumination unit 7b.

[0044] The maintenance unit 8 is a mechanism for performing maintenance of the head 5a of the liquid ejection unit 5. In the case where the liquid ejection unit 5 is a liquid discharge head, the maintenance unit 8 is a mechanism for performing maintenance of the liquid discharge head. The maintenance unit 8 is a mechanism for performing maintenance of the liquid ejection unit 5. In the case where the liquid ejection unit 5 is a liquid discharge head, the maintenance unit 8 is a mechanism for performing maintenance of the liquid discharge head. Figure 1In the illustrated example, the maintenance unit 8 is divided into a unit 8a and a unit 8b. Although not illustrated, the unit 8a has a cover, a wiper, and a suction mechanism. The cover is formed of an elastic member such as rubber, and it prevents drying of ink in the vicinity of the nozzles of the head 5a by covering the nozzles and the nozzle faces of the head 5a described later. Further, the cover prevents thickening or solidification of ink in the vicinity of the nozzles of the head 5a by blocking external light by covering the nozzle faces of the head 5a in the case where the ink is a light-hardening type. The wiper cleans the nozzle faces of the head 5a by wiping the nozzle faces. The suction mechanism refreshes the ink in the nozzles of the head 5a by sucking the ink from the nozzles of the head 5a in a state where the nozzle faces are covered by the cover. The unit 8b is a mechanism for checking the ink ejection function of the head 5a. For example, the unit 8b supports a medium such as paper or a film for printing a pattern for checking. Note that the structure of the maintenance unit 8 is not limited to the structure described above, and for example, the unit 8b can be omitted.

[0045] The placement section 9 is a table having a face 9a on which the work W is placed in order to implement the supply and removal of the work W. The placement section 9 is disposed at a position at which the supply and removal of the work W from the outside of the housing 20 is possible. In the illustrated example, the placement section 9 is disposed on the side of the housing 20 on which the head 5a is disposed. Note that the placement section 9 is not limited to the structure described above, and for example, the placement section 9 can be disposed on the side of the housing 20 on which the head 5a is not disposed. Figure 1 In the illustrated example, the face 9a is able to place two work Ws. In this way, by enabling the face 9a to place a plurality of work Ws, it is possible to place the work Ws for the next printing on the face 9a in advance in a state in which an area for removing the work W in the middle of printing is left empty. Although not illustrated, a concave or convex shape or the like for stabilizing the position and attitude of the placed work W is appropriately formed on the face 9a. Note that the structure of the placement section 9 is not limited to the structure described above, and for example, the placement section 9 can be a structure in which the face 9a is not able to place a plurality of work Ws. Figure 1 The illustrated example, but is an arbitrary structure.

[0046] The hardening unit 10 is a mechanism for causing the ink on the work W to harden or solidify. In the illustrated example, the hardening unit 10 is a mechanism for causing the ink on the work W to harden or solidify by irradiating the work W with light. Note that the hardening unit 10 is not limited to the structure described above, and for example, the hardening unit 10 can be a mechanism for causing the ink on the work W to harden or solidify by heating the work W. Figure 1In the example shown, the hardening unit 10 includes a light-shielding member 10a and a light source 10b. The light-shielding member 10a is a box-shaped light-shielding member with an opening in the Z1 direction, formed to allow the workpiece W to enter, and is made of, for example, resin or metal. The light source 10b is disposed inside the light-shielding member 10a. The light source 10b emits energy such as light, heat, electron beams, or radiation to harden or cure the ink. For example, in the case of an ultraviolet-curing ink, the energy is ultraviolet light, and the light source 10b is composed of a light-emitting element such as an LED (light emitting diode) that emits ultraviolet light. In addition, the light source 10b may also have optical components such as lenses for adjusting the emission direction or emission range of the energy. Furthermore, in addition to the light source 10b, a mirror or the like may be provided inside the light-shielding member 10a to reflect the light from the light source 10b.

[0047] Controller 11 is a robotic arm controller that controls the drive of the first robotic arm 3 and the second robotic arm 4. Control module 12 is a circuit module that is communicatively connected to controller 11 and controls the liquid ejection unit 5. Computer 13 is communicatively connected to controller 11 and control module 12. Although in Figure 1 In the example shown, computer 13 is a laptop, but it is not limited to this; for example, computer 13 could also be a desktop computer. The following is based on... Figure 2 The electrical structure of the three-dimensional printing apparatus 1 will now be explained.

[0048] 1-2. Electrical Structure of the Three-Dimensional Printing Apparatus

[0049] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 1 according to the first embodiment. Figure 2 The electrical structural elements of the three-dimensional printing apparatus 1 are shown in the diagram. Additionally, Figure 1 The electrical structural elements shown can be appropriately divided, partially included in other structural elements, or integrated with other structural elements. For example, some or all of the functions of the controller 11 or control module 12 can be implemented by the computer 13, or by other external devices such as a PC (personal computer) connected to the controller 11 via a network such as a LAN (Local Area Network) or the Internet.

[0050] The controller 11 has a function of controlling driving of the first robot arm 3 and the second robot arm 4, and a function of generating a signal D3 for synchronizing the ejection operation of the ink in the liquid ejection unit 5 with the operation of the first robot arm 3. The controller 11 has a storage circuit 11a and a processing circuit 11b.

[0051] The storage circuit 11a stores various programs executed by the processing circuit 11b and various data processed by the processing circuit 11b. The storage circuit 11a includes, for example, one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). In addition, part or all of the storage circuit 11a can be included in the processing circuit 11b.

[0052] The path information Da is information indicating a path through which the liquid ejection unit 5 should move and a posture of the liquid ejection unit 5 on the path. The path information Db is information indicating a path through which the gripper mechanism 40 should move and a posture of the gripper mechanism 40 on the path. Each of these information is indicated using, for example, coordinate values of a base coordinate system or a general coordinate system. Furthermore, each of these information is determined based on the shape of the workpiece W or the like. The shape of the workpiece W is obtained by, for example, CAD (Computer-Aided Design) data indicating a three-dimensional shape of the workpiece W.

[0053] Here, information related to the position and the posture of the workpiece W at the time of printing is included in the path information Db. Furthermore, information related to the position and the posture of the liquid ejection unit 5 at the time of printing is included in the path information Da. The position and the posture of the liquid ejection unit 5 at the time of printing are determined based on information such as CAD data of the workpiece W and the position and the posture of the workpiece W at the time of printing. Each of the above path information Da and the path information Db is input from the computer 13 to the storage circuit 11a.

[0054] The processing circuit 11b controls the operation of the arm drive mechanism 3a of the first robot arm 3 based on the path information Da, and generates a signal D3. Further, the processing circuit 11b controls the operation of the arm drive mechanism 4a of the second robot arm 4 based on the path information Db. Here, the processing circuit 11b corrects the operation of at least one of the arm drive mechanism 3a and the arm drive mechanism 4a at the time of printing based on the imaging result of the imaging unit 7. In the present embodiment, the processing circuit 11b corrects the operation of the arm drive mechanism 4a at the time of printing based on the imaging result of the imaging unit 7. The processing circuit 11b includes, for example, one or more processors such as a CPU (Central Processing Unit). Alternatively, the processing circuit 11b can include a programmable logic device such as an FPGA (Field-Programmable Gate Array) in place of or in addition to the CPU.

[0055] The arm drive mechanism 3a has a motor for driving each joint of the first robot arm 3, and an encoder for detecting the rotation angle of each joint of the first robot arm 3. Similarly, the arm drive mechanism 4a has a motor for driving each joint of the second robot arm 4, and an encoder for detecting the rotation angle of each joint of the second robot arm 4.

[0056] The processing circuit 11b performs an operation of converting the path information Da into the operation amount such as the rotation angle and the rotation speed of each joint of the first robot arm 3, that is, inverse kinematics calculation. Further, the processing circuit 11b outputs a control signal Sk1 based on the output D1 from each encoder of the arm drive mechanism 3a so that the actual operation amount such as the rotation angle and the rotation speed of each joint becomes the operation result described above. The control signal Sk1 controls the driving of the motor of the arm drive mechanism 3a.

[0057] Similarly, the processing circuit 11b performs an operation of converting the path information Db into the operation amount such as the rotation angle and the rotation speed of each joint of the second robot arm 4, that is, inverse kinematics calculation. Further, the processing circuit 11b outputs a control signal Sk2 based on the output D2 from each encoder of the arm drive mechanism 4a so that the actual operation amount such as the rotation angle and the rotation speed of each joint becomes the operation result described above. The control signal Sk2 controls the driving of the motor of the arm drive mechanism 4a.

[0058] Here, the processing circuit 11b detects the position and attitude of the work W at the time of printing based on the imaging result of the imaging device 7a of the imaging unit 7. Also, the processing circuit 11b corrects the control signal Sk2 at the time of printing based on the detection result and the route information Db so as to reduce the difference between the detection result and the position and attitude indicated by the route information Db. The position and attitude of the work W are obtained, for example, by converting the position and attitude of the work W in the imaging image of the imaging device 7a from an imaging coordinate system to a general coordinate system. Further, the position and attitude of the work W in the imaging coordinate system are calculated, for example, based on the position of a feature point of the work W in the imaging image and the shape information of the work W. In addition, the detection of the position and attitude of the work W based on the imaging result of the imaging device 7a can be implemented by an image processing circuit included in the imaging device 7a or by the computer 13.

[0059] Further, the processing circuit 11b generates a signal D3 based on the output D1 from at least one of the plurality of encoders of the arm driving mechanism 3a. For example, the processing circuit 11b generates a trigger signal including a pulse at the timing when the output D1 from one of the plurality of encoders becomes a predetermined value as the signal D3.

[0060] The control module 12 is a circuit that controls the ejection operation of the ink in the liquid ejection unit 5 based on the signal D3 output from the controller 11 and the print data from the computer 13. The control module 12 has a timing signal generating circuit 12a, a power supply circuit 12b, a control circuit 12c, and a drive signal generating circuit 12d.

[0061] The timing signal generating circuit 12a generates a timing signal PTS based on the signal D3. The timing signal generating circuit 12a is constituted by, for example, a timer that starts the generation of the timing signal PTS as an opportunity of the detection of the signal D3.

[0062] The power supply circuit 12b receives the supply of electric power from a commercial power supply not shown and generates predetermined various electric potentials. The generated various electric potentials are appropriately supplied to each part of the control module 12 and the liquid ejection unit 5. The power supply circuit 12b generates, for example, a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection unit 5. Further, the power supply potential VHV is supplied to the drive signal generating circuit 12d.

[0063] The control circuit 12c generates a control signal SI, a waveform designation signal dCom, a latch signal LAT, a clock signal CLK, and a switching signal CNG based on the timing signal PTS. These signals are synchronized with the timing signal PTS. The waveform designation signal dCom among these signals is input to the drive signal generating circuit 12d, and the other signals are input to the switching circuit 5d of the liquid ejection unit 5.

[0064] The control signal SI is a digital signal for specifying the operation state of the drive element possessed by the head 5a of the liquid discharge unit 5. Specifically, the control signal SI specifies whether or not to supply the drive signal Com described later to the drive element. By this specification, for example, whether or not to discharge ink from the nozzle corresponding to the drive element is specified, or the amount of ink discharged from the nozzle is specified. The waveform specifying signal dCom is a digital signal for specifying the waveform of the drive signal Com. The latch signal LAT and the exchange signal CNG specify the drive timing of the drive element by being used in conjunction with the control signal SI, thereby specifying the discharge timing of ink from the nozzle. The clock signal CLK is a clock signal that becomes a reference synchronized with the timing signal PTS.

[0065] The control circuit 12c includes one or more processors such as CPUs (Central Processing Units), for example. Alternatively, the control circuit 12c can include programmable logic devices such as FPGAs (Field-Programmable Gate Arrays) instead of or in addition to the CPUs.

[0066] The drive signal generation circuit 12d is a circuit that generates the drive signal Com for driving each drive element possessed by the head 5a of the liquid discharge unit 5. Specifically, the drive signal generation circuit 12d has a DA conversion circuit and an amplification circuit, for example. In the drive signal generation circuit 12d, the waveform specifying signal dCom from the control circuit 12c is converted from a digital signal to an analog signal by the DA conversion circuit, and the analog signal is amplified by the amplification circuit using the power supply potential VHV from the power supply circuit 12b, thereby generating the drive signal Com. Here, the signal of the waveform included in the drive signal Com, which is actually supplied to the drive element, is a drive pulse PD. The drive pulse PD is supplied from the drive signal generation circuit 12d to the drive element via the switching circuit 5d of the liquid discharge unit 5. The switching circuit 5d switches whether or not to supply at least a part of the waveform included in the drive signal Com as the drive pulse PD, based on the control signal SI.

[0067] The computer 13 has a function of supplying the controller 11 with information such as the path information Da and the path information Db, and a function of supplying the control module 12 with information such as the print data. In addition, the camera 7a described above can also be connected to the controller 11 via the computer 13. In this case, the computer 13 can either input the result of the imaging of the camera 7a as it is to the controller 11, or calculate the position and the posture of the workpiece W based on the result of the imaging of the camera 7a, and input information indicating the result of the calculation to the controller 11.

[0068] 1-3. Structure of first robot arm

[0069] Figure 3 A perspective view of the first robot arm 3. Hereinafter, the structure of the first robot arm 3 will be described. In addition, as for the structure of the second robot arm 4, since it is the same as that of the first robot arm 3 except for the difference in the end effector mounted, the description thereof will be omitted. However, the structures of the first robot arm 3 and the second robot arm 4 can be made different from each other as already described, and as for this point, the description thereof will be appropriately made in 1-5. and the like described later.

[0070] As shown in FIG. 1, the first robot arm 3 has a base 310 which is an example of a "first base", and an arm 320. Figure 3

[0071] The base 310 is a table which supports the arm 320. In the example shown in FIG. 1, the base 310 is mounted in the Z direction with respect to the face 2a of the base stand 2 described above, and is fixed by screw fastening or the like. Figure 3

[0072] The arm 320 is a six-axis robot arm which has a base end mounted on the base 310, and a tip end which changes the position and the posture three-dimensionally with respect to the base end. Specifically, the arm 320 has arms 321, 322, 323, 324, 325, and 326, and they are connected in this order.

[0073] ​​The arm 321 is coupled to the base 310 via the joint section 330_1 in a manner that enables rotation about the rotation axis O1. The arm 322 is coupled to the arm 321 via the joint section 330_2 in a manner that enables rotation about the rotation axis O2. The arm 323 is coupled to the arm 322 via the joint section 330_3 in a manner that enables rotation about the rotation axis O3. The arm 324 is coupled to the arm 323 via the joint section 330_4 in a manner that enables rotation about the rotation axis O4. The arm 325 is coupled to the arm 324 via the joint section 330_5 in a manner that enables rotation about the rotation axis O5. The arm 326 is coupled to the arm 325 via the joint section 330_6 in a manner that enables rotation about the rotation axis O6.

[0074] Each of the joint sections 330_1 to 330_6 is a mechanism that rotatably couples one of the adjacent two members among the base 310 and the arms 321 to 326 with respect to the other. Although not illustrated in FIG. 1, a driving mechanism that rotates one of the adjacent two members with respect to the other is provided on each of the joint sections 330_1 to 330_6. The driving mechanism has, for example, a motor that generates a driving force for the rotation, a speed reducer that reduces and outputs the driving force, and an encoder such as a rotary encoder that detects the amount of movement such as the angle of the rotation. In addition, the collection of the driving mechanisms of the joint sections 330_1 to 330_6 corresponds to the arm driving mechanism 3a described above. Figure 3 Figure 2 The driving mechanism that rotates one of the adjacent two members with respect to the other is provided on each of the joint sections 330_1 to 330_6. The driving mechanism has, for example, a motor that generates a driving force for the rotation, a speed reducer that reduces and outputs the driving force, and an encoder such as a rotary encoder that detects the amount of movement such as the angle of the rotation. In addition, the collection of the driving mechanisms of the joint sections 330_1 to 330_6 corresponds to the arm driving mechanism 3a described above.

[0075] The rotation axis O1 is an axis that is perpendicular with respect to the face 2a on which the base 310 is fixed. The rotation axis O2 is an axis that is perpendicular with respect to the rotation axis O1. The rotation axis O3 is an axis that is parallel with respect to the rotation axis O2. The rotation axis O4 is an axis that is perpendicular with respect to the rotation axis O3. The rotation axis O5 is an axis that is perpendicular with respect to the rotation axis O4. The rotation axis O6 is an axis that is perpendicular with respect to the rotation axis O5.

[0076] In addition, for these rotation axes, "perpendicular" includes a case where the angle between two rotation axes deviates from 90° by about ±5°, in addition to a case where the angle is strictly 90°. Similarly, "parallel" includes a case where one of two rotation axes is inclined with respect to the other by about ±5°, in addition to a case where the two rotation axes are strictly parallel.

[0077] On the arm 326 that is the most top end of the arms 320 above, a liquid ejection unit 5 is installed as an end effector.

[0078] 1-4. Structure of Liquid Ejection Unit​

[0079] Figure 4 A perspective view showing the outline structure of the liquid discharge unit 5. The following description is made using the a-axis, b-axis, and c-axis that intersect each other as appropriate. Furthermore, one direction along the a-axis is referred to as the al direction, and the direction opposite to the al direction is referred to as the a2 direction. Likewise, the directions opposite to each other along the b-axis are referred to as the bl direction and the b2 direction. Furthermore, the directions opposite to each other along the c-axis are referred to as the cl direction and the c2 direction.

[0080] Here, the a-axis, b-axis, and c-axis are coordinate axes of a tool coordinate system provided in the liquid discharge unit 5, and the relative position and attitude thereof to the X-axis, Y-axis, and Z-axis described above change according to the movement of the first robot arm 3 described above. In the example shown in FIG. 1, the a-axis is parallel to the X-axis described above. In addition, the b-axis is parallel to the Y-axis described above. Furthermore, the c-axis is parallel to the Z-axis described above. Figure 4 In the example shown in FIG. 1, the c-axis is an axis parallel to the sixth rotation axis O6 described above. In addition, although the a-axis, b-axis, and c-axis are typically orthogonal to each other, they are not limited thereto, and may, for example, intersect at an angle in a range of 80° or more and 100° or less. In addition, the tool coordinate system and the base coordinate system described above are brought into correspondence by calibration. Furthermore, the tool coordinate system is set, for example, in such a manner that the center of the nozzle face F described below becomes a reference (tool center point).

[0081] As described above, the liquid discharge unit 5 has the head 5a, pressure regulating valve 5b, and pre-hardening light source 5c. They are supported by the support body 5e shown by a double-dotted line in FIG. 1. Figure 4 In addition, although the support body 5e is shown as a flat box shape in FIG. 1, the shape of the support body 5e is not particularly limited and is an arbitrary shape. Figure 4 In the example shown in FIG. 1, the number of each of the head 5a and pressure regulating valve 5b that the liquid discharge unit 5 has is one, but the number is not limited to one. Figure 4 In the example shown in FIG. 1, the number of each of the head 5a and pressure regulating valve 5b that the liquid discharge unit 5 has is one, but the number is not limited to one.

[0082] The support body 5e is, for example, made of a metal material or the like, and is a substantially rigid body. In addition, although the support body 5e is shown as a flat box shape in FIG. 1, the shape of the support body 5e is not particularly limited and is an arbitrary shape. Figure 4 In the example shown in FIG. 1, the number of each of the head 5a and pressure regulating valve 5b that the liquid discharge unit 5 has is one, but the number is not limited to one.

[0083] The support body 5e described above is mounted on the arm 326 described above. In this way, the head 5a, pressure regulating valve 5b, and pre-hardening light source 5c are integrally supported on the arm 326 by the support body 5e. Therefore, the relative position of each of the head 5a, pressure regulating valve 5b, and pre-hardening light source 5c with respect to the arm 326 is fixed.

[0084] The head 5a has a nozzle face F, and a plurality of nozzles N which are opened on the nozzle face F. In Figure 4 In the example shown, the normal direction of the nozzle face F is the c2 direction, and the plurality of nozzles N are divided into a first nozzle row La and a second nozzle row Lb which are arranged in a mutually spaced-apart manner in the direction along the a axis. Each of the first nozzle row La and the second nozzle row Lb is a collection of a plurality of nozzles N which are arranged in a linear shape in the direction along the b axis. Here, the elements associated with each nozzle N of the first nozzle row La and the elements associated with each nozzle N of the second nozzle row Lb are structures which are substantially symmetrical to each other in the direction along the a axis.

[0085] However, the plurality of nozzles N in the first nozzle row La and the plurality of nozzles N in the second nozzle row Lb can be either identical to each other or different from each other in the position in the direction along the b axis. Furthermore, the elements associated with each nozzle N of one of the first nozzle row La and the second nozzle row Lb can also be omitted. In the following, a structure in which the plurality of nozzles N in the first nozzle row La and the plurality of nozzles N in the second nozzle row Lb are identical to each other in the position in the direction along the b axis will be exemplified.

[0086] Although not shown, the head 5a has, for each nozzle N, a piezoelectric element as a driving element, and a cavity which accommodates ink. Here, the piezoelectric element causes ink to be ejected from the nozzle corresponding to the cavity by causing the pressure of the cavity corresponding to the piezoelectric element to change. Such a head 5a is obtained, for example, by adhering a plurality of substrates, such as a silicon substrate which has been appropriately processed by etching or the like, together using an adhesive or the like. In addition, as a driving element for causing ink to be ejected from a nozzle, a heater which heats ink in a cavity can also be used instead of the piezoelectric element.

[0087] In Figure 4 In the example shown, the pressure regulating valve 5b is located in the cl direction with respect to the head 5a. The pre-hardening light source 5c is located in the a2 direction with respect to the head 5a.

[0088] The pressure regulating valve 5b is connected to the sub tank 6c via the supply pipe 6d of the ink supply unit 6 described above. The pressure regulating valve 5b is a valve mechanism which opens and closes in accordance with the pressure of the ink in the head 5a. By this opening and closing, the pressure of the ink in the head 5a is maintained as a negative pressure within a predetermined range even if the positional relationship of the head 5a and the sub tank 6c changes. Therefore, the stabilization of the meniscus of the ink formed in the nozzles N of the head 5a is achieved. As a result, the entry of air bubbles into the nozzles N, or the overflow of ink from the nozzles N is prevented. In addition, the ink from the pressure regulating valve 5b is appropriately distributed to a plurality of locations of the head 5a via a branch flow path which is not shown.

[0089] The pre-hardening light source 5c emits energy such as light, heat, electron beams, or radiation for semi-hardening or semi-solidifying the ink on the workpiece W. "Semi-hardening" refers to a state in which hardening occurs locally without reaching complete hardening. Similarly, "semi-solidifying" refers to a state in which solidification occurs locally without reaching complete solidification. The pre-hardening light source 5c is constituted by, for example, a light emitting element such as an LED (light emitting diode) that emits ultraviolet light, or the like, similarly to the light source 10b of the hardening unit 10 described above. In addition, the pre-hardening light source 5c can also have an optical member or the like for adjusting the emission direction or emission range of the energy, or the like. In addition, the pre-hardening light source 5c need only be provided as necessary, and can be omitted. Furthermore, the pre-hardening light source 5c can also be used to completely harden the ink on the workpiece W.

[0090] 1-5. Configuration of the hardening unit and the maintenance unit

[0091] Figure 5 A plan view of the three-dimensional object printing apparatus 1 according to the first embodiment. In Figure 5 , the three-dimensional object printing apparatus 1 is shown as viewed in the Z2 direction.

[0092] As described above, the first robot arm 3 has a base 310 fixed to the base 2 as an example of a "first base", and an arm 320, and the head 5a is installed at the top end of the arm 320. On the other hand, as shown in Figure 5 , the second robot arm 4 has a base 410 fixed to the base 2 as an example of a "second base", and an arm 420, and the gripper mechanism 40 that supports the workpiece W is installed at the top end of the arm 420. In addition, the base 410 is installed in the Z direction with respect to the face 2a of the base 2, similarly to the base 310, and is fixed by screw fastening or the like.

[0093] When the base 2 is viewed from above, the positions of the base 310 and the base 410 in the direction of the X axis differ from each other, and the base 310 is located in the X1 direction compared to the base 410. Therefore, when the base 2 is viewed from above, the imaginary line segment LV that links the base 310 and the base 410 extends mainly along the X axis. In addition, the imaginary line segment LV need only link an arbitrary position of the base 310 and an arbitrary position of the base 410 when the base 2 is viewed from above. In the example shown in Figure 5 , the imaginary line segment LV passes through the first axis, which is the rotation axis of the joint closest to the base 2, of each of the first robot arm 3 and the second robot arm 4.

[0094] However, in the example shown in Figure 5In the illustrated example, the positions of the base 310 along the direction of the Y axis and the base 410 are slightly different from each other, and the base 310 is located in the Yl direction compared to the base 410. Thus, the imaginary line segment LV is slightly inclined with respect to the X axis in the plan view of the base 2. Also, in the present embodiment, it can be considered that the imaginary line segment LV is parallel to the X axis in the plan view of the base 2. Further, the imaginary line segment LV can be made parallel to the X axis in the plan view of the base 2.

[0095] The maintenance unit 8 is disposed at a position in the Yl direction with respect to the imaginary line segment LV. On the other hand, the ink supply unit 6, the photographing unit 7, the maintenance unit 8, and the placement portion 9 are disposed at positions in the Y2 direction with respect to the imaginary line segment LV.

[0096] Thus, the imaginary line segment LV passes between the hardening unit 10 and the maintenance unit 8 in the plan view of the base 2. Further, the imaginary line segment LV passes through the photographing range RI in the plan view of the base 2. Thus, it is possible to photograph an object in a position close to the imaginary line segment LV by the photographing unit 7.

[0097] Further, the maintenance unit 8 is located at an inner side of the action range RRl of the first robot arm 3 and at an outer side of the action range RR2 of the second robot arm 4. Here, since the first robot arm 3 uses the maintenance unit 8 in order to perform maintenance of the head 5a, it is necessary to locate the maintenance unit 8 at the inner side of the action range RRl of the first robot arm 3. On the other hand, since the second robot arm 4 does not use the maintenance unit 8, it is not necessary to locate the maintenance unit 8 at the inner side of the action range RR2 of the second robot arm 4. Also, the maintenance unit 8 can be located at the inner side of the action range RR2 of the second robot arm 4 without hindering the action of the second robot arm 4.

[0098] Here, the action range RRl is a region on the inner side of a circle with an arbitrary portion of the base 310 as the center and with the length LRl of the arm 320 as the radius in the plan view of the base 2. The length LRl is the distance between both ends of the arm 320 in a state of extending linearly. Similarly, the action range RR2 is a region on the inner side of a circle with an arbitrary portion of the base 410 as the center and with the length LR2 of the arm 420 as the radius in the plan view of the base 2. The length LR2 is the distance between both ends of the arm 420 in a state of extending linearly.

[0099] The length LRl and the length LR2 can be equal to each other or different from each other. In the present embodiment, the length LRl and the length LR2 are equal to each other. Figure 5In the example shown, the length LR1 of the arm 320 of the first robot arm 3 is shorter than the length LR2 of the arm 420 of the second robot arm 4. This is to reduce vibration at the time of movement of the first robot arm 3 while increasing the degree of freedom of gripping of the workpiece W by the second robot arm 4. Here, from the viewpoint of reducing vibration at the time of movement of the first robot arm 3, it is preferable that the load-carrying capacity of the first robot arm 3 be larger than the load-carrying capacity of the second robot arm 4.

[0100] Further, the maintenance unit 8 is located outside the photographing range RI. This is because if the maintenance unit 8 is photographed by the photographing device 7a, the processing of the photographing results using the photographing device 7a is complicated, and thus this is prevented. Further, the maintenance unit 8 is located outside the illumination range RL of the illumination section 7b. This is because light from the illumination section 7b is prevented from being blocked by the head 5a during maintenance by the maintenance unit 8. In addition, the illumination range RL in the present embodiment refers to a range located on the Y1 direction side with respect to the illumination section 7b.

[0101] Further, although the placement section 9 is located on the same side as the maintenance unit 8 with respect to the imaginary line segment LV when viewed from above the base 2, it is disposed outside the photographing range RI. This is not only because there is no need to photograph the workpiece W placed on the placement section 9 by the photographing device 7a, but also because if photographed, the processing of the photographing results using the photographing device 7a is complicated, and thus this is prevented.

[0102] Further, when viewed from above the base 2, each of the hardening unit 10 and the maintenance unit 8 is located between a first straight line LS1 that passes through the base 310 of the first robot arm 3 and is orthogonal to the imaginary line segment LV and a second straight line LS2 that passes through the base 410 of the second robot arm 4 and is orthogonal to the imaginary line segment LV. This is to achieve miniaturization of the three-dimensional object printing device 1.

[0103] 1-6. Action of the three-dimensional object printing device

[0104] Figure 6 A flowchart showing a flow of the action of the three-dimensional object printing device 1 according to the first embodiment. As shown in the flowchart, the three-dimensional object printing device 1 sequentially executes a material supply step S10, an information acquisition step S20, an adjustment step S30, a first printing step S40, an avoidance step S50, a movement step S60, a second printing step S70, a post-processing step S80, and a material removal step S90. Figure 6

[0105] ​Here, the material supplying step S10 includes a holding step Sll. Further, the post-processing step S80 includes a hardening step S81 and a maintenance step S82, and the hardening step S81 includes a first hardening step S81a and a second hardening step S81b. Hereinafter, each step will be described in order.

[0106] 1-6-1. Material supplying step S10

[0107] Figure 7 is a diagram for describing the material supplying step S10. In the material supplying step S10, first, the holding step Sll is executed. In the holding step Sll, as shown in a solid line in Figure 7 , the gripper mechanism 40 holds the workpiece W located on the placement portion 9 in a state where the second robot arm 4 brings the gripper mechanism 40 close to the placement portion 9. Thereby, the gripper mechanism 40 receives the supply of the workpiece W from the placement portion 9. Thereafter, as shown in a double-dot chain line in Figure 7 , the second robot arm 4 moves the workpiece W from the outside to the inside of the shooting range RI.

[0108] In this step, the action state of the first robot arm 3 is not particularly limited, but is an arbitrary action state. Further, in this step, although the action state of each of the shooting unit 7 and the hardening unit 10 is not particularly limited, in a case where the head 5a is not covered by the maintenance unit 8, it is preferable that the illumination portion 7b of the shooting unit 7 is turned off or the light source 10b of the hardening unit 10 is turned off depending on the position or attitude of the head 5a.

[0109] 1-6-2. Information obtaining step S20

[0110] The information obtaining step S20 is a step of obtaining information related to the relative position of the workpiece W with respect to the base 2 based on the shooting result of the shooting device 7a by the controller 11 in a state where the second robot arm 4 holds the workpiece W as shown in a double-dot chain line in Figure 7 .

[0111] In this step, the illumination portion 7b is turned on. Therefore, from the viewpoint of preventing the ink in the vicinity of the nozzle N from being hardened or solidified by the light from the illumination portion 7b, it is preferable that the first robot arm 3 locates the nozzle face F at the outside of the illumination range RL of the illumination portion 7b or makes the nozzle face F face a direction where the light from the illumination portion 7b is backlight. From the same viewpoint, it is preferable that the nozzle N is covered by the maintenance unit 8 in this step.

[0112] Further, in this step, from the viewpoint of improving the accuracy of the information related to the position obtained based on the imaging result of the imaging device 7a, it is preferable that the head 5a be located outside the imaging range Rl. Here, in this step, at least one of the first robot arm 3 and the second robot arm 4 can have a portion located inside the imaging range Rl. However, in this case, from the viewpoint of improving the accuracy of the information related to the position, it is preferable that the color of the workpiece W be different from the color of the portion of the first robot arm 3 and the second robot arm 4. For example, by painting the portion of the first robot arm 3 and the second robot arm 4 in a color different from the workpiece W, it is possible to improve the contrast between the workpiece W and the portion serving as the background thereof in the captured image obtained by the imaging device 7a. Thus, since the processing of the imaging result in the processing circuit 1 lb is made easier, the accuracy of the information related to the position is improved. In addition, if the portion is made black, it is easy to maintain the contrast in the captured image even in the case where the color is different due to the workpiece W.

[0113] 1-6-3. Adjustment Step S30

[0114] In the adjustment step S30, the controller 11 adjusts the position of the workpiece W located inside the imaging range Rl by controlling the movement of the second robot arm 4 based on the information obtained in the information obtaining step S20.

[0115] The position and the posture of the workpiece W adjusted by this step are the first state, and are the position and the posture of the workpiece W at the time of execution of the first printing step S40. Here, the position of the workpiece W adjusted by this step is closer to the imaginary line segment LV than the position of the workpiece W at the time of execution of the holding step Sll described above when viewed from above the base 2. Further, the position of the workpiece W adjusted by this step is closer to the imaginary line segment LV than at the time of execution of the hardening step S81 and the maintenance step S82 when viewed from above the base 2.

[0116] 1-6-4. First Printing Step S40

[0117] Figure 8 is a view for explaining the movement of the first robot arm 3 in the first printing step S40. In the first printing step S40, as shown in FIG. 8, while the second robot arm 4 fixes the position and the posture of the workpiece W to the first state, the head 5a ejects ink toward the workpiece W while the first robot arm 3 relatively moves the head 5a and the workpiece W inside the imaging range Rl. Figure 8 Figure 8 ​In the example shown, the first robot arm 3 moves the head 5a in a direction along the long axis of the workpiece W. In addition, the attitude of the workpiece W in the first printing step S40 is not particularly limited, but is an arbitrary attitude.

[0118] Thus, in this step, the first robot arm 3 is caused to act under the condition that the second robot arm 4 does not act. Therefore, it is possible to prevent vibration of the workpiece W. In addition, the vibration tends to occur due to the workpiece W being held in a detachable manner by the gripper mechanism 40, and becomes significant in the case where the second robot arm 4 is caused to act in the first printing step, thereby causing the landing position of the ink droplets to deviate and leading to a reduction in the quality of the image. Furthermore, in the case where the rigidity of the workpiece W is reduced due to the material or shape, the vibration of the workpiece W also tends to become significant, thereby also leading to a reduction in the quality of the image. In contrast, the head 5a mounted on the first robot arm is not held by a gripper mechanism or the like, and thus tends to be less likely to vibrate than the workpiece W. Therefore, in this step, by causing the first robot arm 3 to act under the condition that the second robot arm 4 does not act, it is possible to suppress a reduction in the quality of the image due to the vibration as described above. Here, from the viewpoint of reducing the meandering of the movement path of the head 5a, it is desirable to make the number of joints of the first robot arm 3 that act in this step as small as possible, and furthermore, it is preferable that the first robot arm 3 be caused to act by the action of three joints of mutually parallel axes of rotation. In Figure 8 In the example shown, the three axes of rotation are the axis of rotation O2, the axis of rotation O3, and the axis of rotation O5.

[0119] In this step, it is preferable that the illumination section 7b be turned off from the viewpoint of preventing the ink in the vicinity of the nozzle N from being hardened or cured by the light from the illumination section 7b.

[0120] Figure 9 A diagram for explaining the printing region of the workpiece W in the first printing step S40. As Figure 9 As shown in this step, while the head 5a is caused to scan along the first region RP1 of the different first region RP1 and second region RP2 of the workpiece W by the first robot arm 3, the head 5a ejects ink toward the first region RP1. In Figure 9 In the example shown, the first region RP1 and a portion of the second region RP2 overlap each other. In addition, it is also possible to make the first region RP1 and the second region RP2 not overlap each other. For example, it is also possible to make the first region RP1 and the second region RP2 be in a front-back relationship.

[0121] In this step, the pre-hardening light source 5c can also be lit. In this case, the ink on the workpiece W can be pre-hardened. In addition, after this step, the pre-hardening light source 5c can be lit while the ink is not ejected from the head 5a, with the pre-hardening light source 5c being scanned along the first region RP1 by the first robot arm 3.

[0122] 1-6-5. Avoidance Step S50

[0123] Figure 10 is a diagram for describing the avoidance step S50. In the avoidance step S50, as shown in Figure 10 , the distance between the head 5a and the workpiece W is increased by the first robot arm 3 compared to when the first printing step S40 is performed. In the example shown in Figure 10 , a state in which the head 5a is covered by the maintenance unit 8 is illustrated. In addition, in this step, the head 5a can not be covered by the maintenance unit 8. However, in this case, it is preferable that the illumination part 7b of the imaging unit 7 be turned off or the light source 10b of the hardening unit 10 be turned off depending on the position or attitude of the head 5a.

[0124] 1-6-6. Movement Step S60

[0125] Figure 11 is a diagram for describing the movement step S60. In the movement step S60, the second robot arm 4 changes the position and attitude of the workpiece W from a first state to a second state different from the first state. In the example shown in Figure 11 , the first state is the state shown in double-dotted line in Figure 11 , and the second state is the state shown in solid line in Figure 11 . The second state is the state of the position and attitude of the workpiece W at the time of execution of the second printing step S70. In addition, this step can include a step of adjusting the position of the workpiece W in the same manner as the adjustment step S30 described above.

[0126] 1-6-7. Second Printing Step S70

[0127] In the second printing step S70, as shown in Figure 11 , printing is performed in the same manner as the first printing step S40 described above, except that the second region RP2 is printed. Here, in the second printing step S70, the head 5a ejects ink toward the workpiece W while the head 5a and the workpiece W are relatively moved inside the imaging range RI by the first robot arm 3 in a state in which the second robot arm 4 fixes the position and attitude of the workpiece W to the second state. Furthermore, the movement of the first robot arm 3 in this step is the same as the movement of the first robot arm 3 in the first printing step S40 described above.

[0128] In this step, the pre-hardening light source 5c can also be lit. In this case, the ink on the workpiece W can be pre-hardened. In addition, after this step, the pre-hardening light source 5c can be lit while the first robot arm 3 causes the pre-hardening light source 5c to scan along the second region RP2 without the ink being ejected from the head 5a.

[0129] 1-6-8. Post-processing step S80

[0130] Figure 12 A diagram for explaining the hardening step S81 and the maintenance step S82. As described, the post-processing step S80 includes the hardening step S81 and the maintenance step S82.

[0131] In the hardening step S81, as shown in FIG. 8, in a state where the second robot arm 4 causes the workpiece W to approach the hardening unit 10, the hardening unit 10 irradiates the ink on the workpiece W with energy. Here, in the present embodiment, as described, the hardening step S81 includes a first hardening step S81a and a second hardening step S81b. Figure 12

[0132] In the first hardening step S81a, while the second robot arm 4 changes the relative position and attitude of the hardening unit 10 and the workpiece W, the hardening unit 10 irradiates the ink on the first region RP1 with energy. In the second hardening step S81b, while the second robot arm 4 changes the relative position and attitude of the hardening unit 10 and the workpiece W, the hardening unit 10 irradiates the ink on the second region RP2 with energy. In these steps, as long as the ink can be irradiated with energy, there is no problem caused by the vibration of the workpiece W as in the first printing step S40 or the second printing step S70. Here, it is preferable that the first hardening step S81a and the second hardening step S81b be executed in this order. This is because, by reducing the difference in the time before the ink on the first region RP1 and the ink on the second region RP2 are irradiated with energy after being ejected with ink, respectively, it is possible to reduce the difference between the quality of the first region RP1 and the quality of the second region RP2. In addition, the first hardening step S81a and the second hardening step S81b can also be substantially simultaneously implemented.

[0133] In the maintenance step S82, as shown in FIG. 9, in a state where the second robot arm 4 causes the workpiece W to approach the maintenance unit 20, the maintenance unit 20 performs maintenance on the workpiece W. Here, in the present embodiment, as described, the maintenance step S82 includes a first maintenance step S82a and a second maintenance step S82b. Figure 12 ​As shown, in a state where the head 5a is brought close to the maintenance unit 8 by the first robot arm 3, maintenance of the head 5a by the maintenance unit 8 is performed. In addition, maintenance refers to covering of the nozzles and the nozzle surface by the cover of the unit 8a, suction of ink from the nozzles of the head 5a in a state where the nozzles and the nozzle surface are covered by the cover, cleaning of the nozzle surface of the head 5a by the wiper of the unit 8a, printing of a pattern for inspection by the head 5a in the unit 8b, and the like. However, in a case where the illumination section 7b or the hardening unit 10 emits light during execution of the maintenance step S82, it is preferable that the maintenance be an operation in which the nozzles and the nozzle surface are covered by the cover. Here, from the viewpoint of shortening of the processing time and the like, it is preferable that the maintenance step S82 be executed during execution of the first hardening step S81a.

[0134] Furthermore, from the viewpoint of reducing bleeding of an image caused by flow of ink on the workpiece W by causing the ink on the workpiece W to harden immediately, it is preferable that the position of the workpiece W at the time of execution of the hardening step S81 be close to the position of the workpiece W at the time of execution of the first printing step S40 or the second printing step S70. Therefore, it is preferable that the workpiece movement distance DW, which is a movement distance of the workpiece W required for shifting from the first printing step S40 or the second printing step S70 to the hardening step S81, be shorter than the head movement distance DH, which is a movement distance of the head 5a required for shifting from the first printing step S40 or the second printing step S70 to the maintenance step S82.

[0135] In addition, the workpiece movement distance DW is a distance between the workpiece W at the time of execution of the first printing step S40 or the second printing step S70 and the workpiece W at the time of execution of the hardening step S81, in a plan view of the base 2. The head movement distance DH is a distance between the head 5a at the time of execution of the first printing step S40 or the second printing step S70 and the head 5a at the time of execution of the maintenance step S82, in a plan view of the base 2.

[0136] 1-6-9. Material removal step S90

[0137] Figure 13 is a diagram for explaining the material removal step S90. In the material removal step S90, first, as shown in Figure 13 The workpiece W is moved to the placement section 9 by the second robot arm 4. In this state, the printed workpiece W is placed on the placement section 9 by detaching the workpiece W by the gripping mechanism 40. The printed workpiece W placed on the placement section 9 is taken out to the outside of the housing 20, for example, by a user.

[0138] In this step, the action state of the first robot arm 3 is not particularly limited, and is an arbitrary action state. Furthermore, in this step, the action state of each of the photographing unit 7 and the hardening unit 10 is also not particularly limited, but in a case where the head 5a is not covered by the maintenance unit 8, preferably, the illumination part 7b of the photographing unit 7 is turned off or the light source 10b of the hardening unit 10 is turned off in accordance with the position or attitude of the head 5a. In addition, the maintenance step S82 can also be performed in this step.

[0139] As described above, the three-dimensional object printing apparatus 1 performs printing on the three-dimensional work W. Here, as described above, the three-dimensional object printing apparatus 1 has the photographing apparatus 7a, the first robot arm 3, and the second robot arm 4. The photographing apparatus 7a is fixed to the base 2, and photographs an object located inside the photographing range RI. The first robot arm 3 supports the head 5a having a nozzle N that ejects ink that is an example of a "liquid", and changes the position and attitude of the head 5a. The second robot arm 4 supports the work W, and changes the position and attitude of the work W.

[0140] Furthermore, as described above, the three-dimensional object printing apparatus 1 performs the material supply step S10, and the first printing step S40 or the second printing step S70 that are examples of a "printing step". In the material supply step S10, the second robot arm 4 moves the work W from the outside to the inside of the photographing range RI. In the first printing step S40 or the second printing step S70, the head 5a ejects ink toward the work W while at least one of the first robot arm 3 and the second robot arm 4 relatively moves the head 5a and the work W inside the photographing range RI.

[0141] In the above three-dimensional object printing apparatus, by using the first robot arm 3 and the second robot arm 4, it is possible to independently change the position and attitude of each of the head 5a and the work W. Therefore, compared to a structure in which only the position and attitude of one of the head 5a and the work W is changed, it is possible to cause the head 5a to approach the work W over a larger range. As a result, even if the work W is a three-dimensional shape that is various, it is possible to appropriately perform printing on the work W.

[0142] On this basis, in the first printing step S40 or the second printing step S70, the head 5a and the work W are relatively moved inside the imaging range Rl of the imaging device 7a by at least one of the first robot arm 3 and the second robot arm 4. Therefore, the position and the posture of the work W at the time of execution of the first printing step S40 or the second printing step S70 can be detected on the basis of the imaging result of the imaging device 7a. Therefore, in the first printing step S40 or the second printing step S70, even if the support position of the work W by the second robot arm 4 is shifted, the error occurring in the relative position and the posture of the head 5a and the work W can be reduced by the correction by controlling the movement of at least one of the first robot arm 3 and the second robot arm 4 on the basis of the imaging result of the imaging device 7a. According to the above, compared with a structure in which the movement of the first robot arm 3 and the second robot arm 4 is controlled without using the imaging result of the imaging device 7a in the first printing step S40 or the second printing step S70, the reduction in the image quality can be reduced.

[0143] As described above, the second robot arm 4 has the gripper mechanism 40 that holds the work W in a detachable manner. When the gripper mechanism 40 is used in the second robot arm, the support position of the work W by the second robot arm 4 is easily shifted from the desired position. Therefore, in this case, the effect obtained by controlling the movement of at least one of the first robot arm 3 and the second robot arm 4 on the basis of the imaging result of the imaging device 7a is more remarkable.

[0144] Further, as described above, each of the first robot arm 3 and the second robot arm 4 is a vertical multi-joint robot arm. Therefore, compared with a structure using other mechanisms such as a horizontal multi-joint robot arm, various changes in the position and the posture of the head 5a and the work W can be made.

[0145] Here, as described above, it is preferable that the length LRl of the arm 320 of the first robot arm 3 be shorter than the length LR2 of the arm 420 of the second robot arm 4. In this case, there is an advantage that the vibration at the time of movement of the first robot arm 3 is easily smaller than the second robot arm 4. This advantage contributes to the improvement in the image quality. Further, by making the length of the arm 420 of the second robot arm 4 longer than the length of the arm 320 of the first robot arm 3, the range of movement of the second robot arm 4 can be increased. Therefore, the supply or removal of the work W or the treatment of hardening or solidification of the ink on the work W can be performed at an arbitrary place in a wide range.

[0146] Further, as described above, it is preferable that the load-carrying capacity of the first robot arm 3 be larger than that of the second robot arm 4. In this case, there is an advantage that the vibration at the time of movement of the first robot arm 3 is made smaller than that of the second robot arm 4. This advantage contributes to the improvement of the image quality. In particular, the larger the weight of the end effector of the first robot arm 3, the more remarkable the effect obtained by this advantage.

[0147] As described above, the stereoscopic object printing apparatus 1 also has the placement section 9. The placement section 9 is disposed outside the imaging range RI and is capable of placing the workpiece W. The gripping mechanism 40 receives the supply of the workpiece W from the placement section 9. Thus, since the placement section 9 is disposed outside the imaging range RI of the imaging device 7a, the variation in the imaging conditions of the imaging device 7a due to the presence or absence of the workpiece W on the placement section 9 or the like is prevented. Therefore, compared with a structure in which the placement section 9 is disposed inside the imaging range RI, the processing of the imaging results using the imaging device 7a can be simplified. In addition, although a structure in which the placement section 9 is used for both the supply and the take-out of the workpiece W is exemplified in the present embodiment, the structure is not limited thereto, and for example, the placement section 9 can be used only for the supply of the workpiece. In this case, for example, a table or a conveyer belt or the like on which the workpiece W can be placed is provided separately from the placement section 9.

[0148] Further, as described above, the stereoscopic object printing apparatus 1 executes the information acquisition step S20 between the material supply step S10 and the first printing step S40 or the second printing step S70. In the information acquisition step S20, information related to the relative position of the workpiece W with respect to the base 2 is acquired on the basis of the imaging results of the imaging device 7a. Therefore, the position of the workpiece W after the material supply step S10 can be detected on the basis of the information acquired in the information acquisition step S20, and the adjustment step S30, and the first printing step S40 or the second printing step S70 can be executed on the basis of the detected position.

[0149] Here, as described above, in the information acquisition step S20, the head 5a is located outside the imaging range RI. Therefore, in the information acquisition step S20, the presence of the head 5a does not need to be taken into account in order to acquire the information related to the relative position of the workpiece W with respect to the base 2. As a result, compared with a structure in which the head 5a is located inside the imaging range RI of the imaging device 7a, the processing in the information acquisition step S20 can be simplified, or the accuracy of the information acquired in the information acquisition step S20 can be improved.

[0150] Further, as described above, the stereoscopic object printing apparatus 1 also has the maintenance unit 8 that covers the nozzle N. The maintenance unit 8 is located outside the shooting range RI. Therefore, since the maintenance unit 8 is not shot by the shooting device 7a, it is possible to simplify the processing of the shooting result using the shooting device 7a. Further, in the information obtaining step S20, the nozzle N is covered by the maintenance unit 8. Therefore, it is possible to prevent hardening or solidification of the ink near the nozzle N caused by the illumination for shooting by the shooting device 7a.

[0151] Here, as described above, the maintenance unit 8 is located inside the action range RR1 of the first robot arm 3 and outside the action range RR2 of the second robot arm 4. Therefore, it is possible to prevent the maintenance unit 8 from becoming an obstacle to the action of the second robot arm 4. Further, it also has the advantage that it is easy to prevent the ink near the nozzle N from hardening or solidifying due to the energy from the hardening unit 10 at the time of execution of the hardening step S81.

[0152] Further, as described above, the stereoscopic object printing apparatus 1 also executes the adjustment step S30 between the information obtaining step S20 and the first printing step S40 or the second printing step S70. In the adjustment step S30, the position of the workpiece W located inside the shooting range RI is adjusted. Here, in the adjustment step S30, the action of the second robot arm 4 is controlled based on the information obtained in the information obtaining step S20. Therefore, even if the support position of the workpiece W by the second robot arm 4 deviates from the required position, it is possible to correct the deviation. In addition, it is also possible to make the movement step S60 described above include the same processing as the adjustment step S30.

[0153] Further, as described above, the stereoscopic object printing apparatus 1 also has the illumination part 7b that illuminates the inside of the shooting range RI. Here, in the information obtaining step S20, the illumination part 7b is turned on. Therefore, in the information obtaining step S20, since the contrast of the workpiece W is improved by the illumination of the illumination part 7b, it is possible to improve the accuracy of the information obtained in the information obtaining step S20. On the contrary, in the first printing step S40 or the second printing step S70, the illumination part 7b is turned off. Therefore, in the first printing step S40 or the second printing step S70, it is possible to prevent hardening or solidification of the ink near the nozzle N caused by the illumination of the illumination part 7b.

[0154] Here, as described above, the maintenance unit 8 is located outside the illumination range RL of the illumination part 7b. Therefore, it is possible to prevent hardening or solidification of the ink near the nozzle N caused by the illumination of the illumination part 7b.

[0155] Further, as described above, the head 5a has a nozzle face F provided with the nozzle N. The nozzle face F is located outside the illumination range RL of the illumination section 7b or in a direction toward a back light of light from the illumination section 7b at the time of lighting of the illumination section 7b. Therefore, it is possible to prevent hardening or solidification of ink in the vicinity of the nozzle N caused by illumination of the illumination section 7b.

[0156] Here, as described above, in the information acquisition step S20, it is preferable that the color of at least a portion of the first robot arm 3 located inside the photographing range RI be different from the color of the workpiece W. In this case, in the information acquisition step S20, since the contrast of the workpiece W is improved by the illumination of the illumination section 7b, it is possible to improve the accuracy of the information obtained in the information acquisition step S20.

[0157] Likewise, in the information acquisition step S20, it is preferable that the color of at least a portion of the second robot arm 4 located inside the photographing range RI be different from the color of the workpiece W. In this case, in the information acquisition step S20, since the contrast of the workpiece W is improved by the illumination of the illumination section 7b, it is possible to improve the accuracy of the information obtained in the information acquisition step S20.

[0158] Further, as described above, the first robot arm 3 has the base 310 as an example of a "first base" fixed to the base 2. Likewise, the second robot arm 4 has the base 410 as an example of a "second base" fixed to the base 2. Here, in a plan view of the base 2, an imaginary line segment LV connecting the base 310 and the base 410 passes through the photographing range RI. Therefore, compared to a case where the imaginary line segment LV does not pass through the photographing range RI in the plan view of the base 2, it is possible to improve the degree of freedom of the position and the posture of each of the workpiece W and the head 5a within the photographing range RI.

[0159] As described above, the mounting direction of the base 310 of the first robot arm 3 and the base 410 of the second robot arm 4 with respect to the base 2 is not limited to the example of the present embodiment, but can be appropriately changed. For example, both or one of the first robot arm 3 and the second robot arm 4 can be fixed in a manner such that it is hung down from a ceiling or a beam or the like provided along the X direction or the Y direction, or both or one of the first robot arm 3 and the second robot arm 4 can be fixed to a wall surface or the like provided along the Z direction.

[0160] Here, the "plan view of the base 2" is described. In a case where the base 310 of the first robot arm 3 and the base 410 of the second robot arm 4 are fixed to the base 2 in the same installation direction, the "plan view of the base 2" refers to a state when viewed in a direction along the installation direction. For example, in the present embodiment, the installation direction is the Z direction, and the "plan view of the base 2" refers to a state when viewed in the Z direction. On the other hand, in a case where the base 310 of the first robot arm 3 and the base 410 of the second robot arm 4 are fixed to the base 2 in different installation directions, the "plan view of the base 2" refers to a state when viewed in a direction along the installation direction of either one of the first robot arm 3 and the second robot arm 4 selected at random.

[0161] Further, as described above, in a case where the ink ejected from the head 5a has a light hardening property, the ink on the work W can be caused to harden by using the hardening unit 10 or the like to cause the ink to harden, so as to be left at a desired position. As a result, printing can be performed on the three-dimensional work W with high precision.

[0162] As described above, the three-dimensional object printing apparatus 1 performs the first printing step S40. In the first printing step S40, the head 5a ejects ink toward the first region RP1 while the first robot arm 3 causes the head 5a to scan along the first region RP1 of the work W. Thus, printing can be performed on the first region RP1 of the work W. Here, in the first printing step S40, the second robot arm 4 fixes the position and the posture of the work W to the first state. Thus, vibration of the work W in the first printing step S40 is prevented. As a result, compared to a configuration in which the second robot arm 4 is caused to operate in the first printing step S40, the quality of the image can be improved.

[0163] Further, as described above, the three-dimensional object printing apparatus 1 also has the hardening unit 10. The hardening unit 10 is fixed to the base 2 and emits energy that causes the ink from the head 5a to harden or solidify. The three-dimensional object printing apparatus 1 performs the first hardening step S81a after the execution of the first printing step S40. In the first hardening step S81a, the hardening unit 10 irradiates energy toward the ink on the first region RP1 while the second robot arm 4 causes the relative position and the posture of the hardening unit 10 and the work W to change. Thus, in the first hardening step S81a, the ink ejected onto the work W in the first printing step S40 can be caused to harden or solidify by the energy from the hardening unit 10.

[0164] In this case, in the first hardening step S81a, since the relative position and attitude of the hardening unit 10 and the workpiece W are changed by the second robot arm 4, even if the hardening unit 10 is fixed to the base 2, the energy from the hardening unit 10 can be properly irradiated to the ink on the workpiece W. Also, in the first hardening step S81a, even if the workpiece W vibrates, the problem at the time of printing does not occur. Further, the control accuracy of the position and attitude of the workpiece W in the first hardening step S81a is lower than the control accuracy of the position and attitude of the head 5a in the first printing step S40.

[0165] As described above, preferably, the three-dimensional object printing apparatus 1 executes the maintenance step S82 during execution of the first hardening step S81a. In the maintenance step S82, the maintenance of the head 5a by the maintenance unit 8 is performed. Thus, by overlapping at least a part of the execution period of the hardening step S81 and the execution period of the maintenance step S82 with each other, the time required for these steps can be shortened compared to the case where the maintenance step S82 is not executed during execution of the first hardening step S81a.

[0166] In this case, the first hardening step S81a is executed using the second robot arm 4 without using the first robot arm 3, and, in contrast, the maintenance step S82 is executed using the first robot arm 3 without using the second robot arm 4. Therefore, the maintenance step S82 can be executed during execution of the first hardening step S81a. Further, since the head 5a is covered by the maintenance unit 8 at the time of execution of the maintenance step S82, it is also possible to prevent the ink in the vicinity of the nozzle N from being hardened or solidified due to the energy from the hardening unit 10 in the first hardening step S81a.

[0167] Further, as described above, the three-dimensional object printing apparatus 1 executes the moving step S60 after execution of the first printing step S40. In the moving step S60, the second robot arm 4 changes the position and attitude of the workpiece W from the first state described above to a second state different from the first state. Therefore, after execution of the moving step S60, printing can be performed in the same movement of the first robot arm 3 as in the first printing step S40 to a region different from the printing region of the workpiece W in the first printing step S40. Also, in the moving step S60, the position adjustment of the workpiece W is performed as in the adjustment step S30 described above as needed.

[0168] Here, as described above, the stereoscopic object printing apparatus 1 executes the second printing step S70 after the execution of the moving step S60. In the second printing step S70, the head 5a ejects ink toward the second region RP2 while the first arm 3 causes the head 5a to scan along the second region RP2 of the workpiece W different from the first region RP1. Thus, printing can be performed on the second region of the workpiece W. Here, in the second printing step S70, the second arm 4 fixes the position and the posture of the workpiece W to the second state described above. Thus, vibration of the workpiece W in the second printing step S70 is prevented. As a result, compared with a configuration in which the second arm 4 is caused to act in the second printing step S70, the quality of the print can be improved.

[0169] In the present embodiment, as described above, the action of the first arm 3 in the first printing step S40 and the action of the first arm 3 in the second printing step S70 are identical to each other. Thus, compared with a case in which the actions of the first arm 3 in these steps are different from each other, the difference in the movement path of the head 5a in these steps can be reduced. This is because, by causing the first arm 3 to repeatedly perform the same action, the reproducibility of the movement path of the head 5a can be improved. In this way, by reducing the difference in the movement path of the head 5a in these steps, the quality of the print realized by the first printing step S40 and the second printing step S70 can be improved.

[0170] Here, by causing the first arm 3 to act by the action of the joints of the three rotation axes parallel to each other, the meandering of the movement path of the head 5a can also be reduced.

[0171] Further, as described above, the stereoscopic object printing apparatus 1 executes the second hardening step S81b after the execution of the second printing step. In the second hardening step S81b, the hardening unit 10 irradiates energy toward the ink on the second region RP2 while the second arm 4 changes the relative position and the posture of the hardening unit 10 and the workpiece W. Thus, in the second hardening step S81b, the ink ejected onto the workpiece W in the second printing step S70 can be hardened or solidified by the energy from the hardening unit 10.

[0172] Here, in the second hardening step S81b, since the relative position and the posture of the hardening unit 10 and the workpiece W are changed by the second arm 4, even if the hardening unit 10 is fixed to the base 2, the energy from the hardening unit 10 can be appropriately irradiated toward the ink on the workpiece W. In addition, in the second hardening step S81b, the problem as in the printing does not occur even if the workpiece W vibrates. Further, the control accuracy of the position and the posture of the workpiece W in the second hardening step S81b is lower than the control accuracy of the position and the posture of the head 5a in the second printing step S70.

[0173] As described above, preferably, the stereoscopic object printing apparatus 1 executes the maintenance step S82 during execution of the second hardening step S81b. In the maintenance step S82, maintenance of the head 5a by the maintenance unit 8 is performed. Thus, by overlapping at least a part of the execution period of the hardening step S81 and the execution period of the maintenance step S82 with each other, it is possible to shorten the time required for these steps compared to the case where the maintenance step S82 is not executed during execution of the second hardening step S81b.

[0174] Here, the second hardening step S81b is executed using the second robot arm 4 without using the first robot arm 3, and, in contrast, the maintenance step S82 is executed using the first robot arm 3 without using the second robot arm 4. Therefore, it is possible to execute the maintenance step S82 during execution of the second hardening step S81b. Further, since the head 5a is covered by the maintenance unit 8 at the time of execution of the maintenance step S82, it is also possible to prevent the ink in the vicinity of the nozzle N from being hardened or solidified due to the energy from the hardening unit 10 in the second hardening step S81b.

[0175] As described above, preferably, the stereoscopic object printing apparatus 1 executes the first printing step S40, the second printing step S70, the first hardening step S81a, and the second hardening step S81b in this order. In this case, it is possible to continuously execute the first printing step S40 and the second printing step S70. Therefore, it has an advantage that it is easy to reduce the difference in the movement path of the head 5a in the first printing step S40 and the second printing step S70. Further, by executing the first hardening step S81a and the second hardening step S81b in this order, it is possible to reduce the difference in the time from when the ink is ejected in each printing step to when the energy is irradiated in each hardening step compared to the case where they are executed in the reverse order. Thereby, it is possible to reduce the difference in the quality of the images formed in different printing steps. In addition, the first hardening step S81a and the second hardening step S81b can also be substantially simultaneous.

[0176] Further, as described above, the stereoscopic object printing apparatus 1 executes the avoidance step S50 between the first printing step S40 and the movement step S60. In the avoidance step S50, the first robot arm 3 increases the distance between the head 5a and the workpiece W compared to when the first printing step S40 is executed. Therefore, it has an advantage that it is easy to cause the second robot arm 4 to operate without interfering with the first robot arm 3 after execution of the avoidance step S50. Further, it is also possible to perform maintenance of the head 5a and the like at a position where avoidance is performed compared to when the first printing step S40 is executed after execution of the avoidance step S50.

[0177] Furthermore, in the stereolithography printing apparatus 1, when viewed from above the base 2, the imaginary line segment LV passes between the hardening unit 10 and the maintenance unit 8. That is, the hardening unit 10 is positioned within one of the two regions divided by the imaginary line segment LV, while the maintenance unit 8 is positioned within the other region. Therefore, interference between the first robotic arm 3 and the second robotic arm 4 can be prevented when the processing performed by the hardening unit 10 and the maintenance unit 8 is performed simultaneously. Specifically, when the first robotic arm 3 and the second robotic arm 4 move from the first printing step S40 or the second printing step S70 to the hardening step S81, the head 5a and the workpiece W move in a direction separating from each other. Therefore, interference between the first robotic arm 3 and the second robotic arm 4 can be prevented after the execution of the first printing step S40 or the second printing step S70. Additionally, in this embodiment, as described above, the hardening step S81 includes a first hardening step S81a and a second hardening step S81b.

[0178] Here, as mentioned above, it is preferable that, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than during the execution of the hardening step S81. The closer the position of the workpiece W is to the imaginary line segment LV, the higher the degree of freedom of movement of the first robotic arm 3 and the second robotic arm 4 during the execution of the first printing step S40 or the second printing step S70. Therefore, by making the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 closer to the imaginary line segment LV than during the execution of the hardening step S81, the degree of freedom of posture of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can be improved.

[0179] For the same reason, as mentioned above, it is preferable that, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than the position of the workpiece W during the execution of the maintenance step S82. In this case, the degree of freedom of the orientation of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can also be improved.

[0180] Furthermore, as mentioned above, in the stereolithography printing apparatus 1, the workpiece movement distance DW is shorter than the head movement distance DH. Additionally, the workpiece movement distance DW is the distance between the workpiece W during the execution of the first printing step S40 or the second printing step S70, and the workpiece W during the execution of the hardening step S81, when viewed from above the base 2. The head movement distance DH is the distance between the head 5a during the execution of the first printing step S40 or the second printing step S70, and the head 5a during the execution of the maintenance step S82, when viewed from above the base 2.

[0181] Thus, by making the workpiece movement distance DW shorter than the head movement distance DH, the transfer from the first printing step S40 or the second printing step S70 to the hardening step S81 can be carried out quickly even without increasing the movement speed of the workpiece W. As a result, both image quality and productivity can be achieved. Furthermore, since the movement speed of the workpiece W is not increased, even if the workpiece W is supported on the second robotic arm 4 by the gripper mechanism 40, it is possible to prevent the workpiece W from detaching from the second robotic arm 4 or from shifting its position. Additionally, since the head 5a is fixed to the first robotic arm 3 by screws or the like, there is no problem even if the movement speed of the head 5a is increased. Therefore, even if the head movement distance DH is long, the transfer from the first printing step S40 or the second printing step S70 to the maintenance step S82 can be carried out quickly by increasing the movement speed of the head 5a.

[0182] Furthermore, as mentioned above, when viewed from above the base 2, the mounting section 9 and the maintenance unit 8 are located on the same side relative to the imaginary line segment LV. That is, when viewed from above the base 2, the mounting section 9 and the maintenance unit 8 are arranged within one of the two regions divided by the imaginary line segment LV. Therefore, compared to a structure where the mounting section 9 and the maintenance unit 8 are located on opposite sides relative to the imaginary line segment LV when viewed from above the base 2, it is easier to miniaturize the overall device.

[0183] Furthermore, as described above, the stereolithography printing apparatus 1 performs a holding step S11 in which the gripper mechanism 40 receives the workpiece W from the mounting section 9. Here, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than the position of the workpiece W during the holding step S11. The closer the position of the workpiece W is to the imaginary line segment LV, the higher the degree of freedom of movement of the first robotic arm 3 and the second robotic arm 4 during the execution of the first printing step S40 or the second printing step S70. Therefore, by making the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 closer to the imaginary line segment LV than the position during the holding step S11, the degree of freedom of posture of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can be improved. Additionally, as described above, the holding step S11 is included in the material feeding step S10.

[0184] Furthermore, as mentioned above, in the stereolithography printing apparatus 1, when viewed from above the base 2, each of the hardening unit 10 and the maintenance unit 8 is located between a first straight line LS1 that passes through the base 310 of the first robotic arm 3 and is orthogonal to the imaginary line segment LV, and a second straight line LS2 that passes through the base 410 of the second robotic arm 4 and is orthogonal to the imaginary line segment LV. Therefore, it is possible to achieve miniaturization of the stereolithography printing apparatus 1 as a whole.

[0185] 2. Second Implementation Method

[0186] The second embodiment of the present invention will now be described. In the embodiments illustrated below, the symbols used in the description of the first embodiment are retained for elements that have the same function or effect as those in the first embodiment, and detailed descriptions of each are omitted as appropriate.

[0187] Figure 14 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to the second embodiment. This embodiment is the same as the first embodiment described above, except that the execution order of the first curing step S81a, the second curing step S81b, and the maintenance step S82 is different.

[0188] In this embodiment, a post-processing step S80A, including a first hardening step S81a and a maintenance step S82, is performed between the first printing step S40 and the avoidance step S50. Furthermore, a post-processing step S80B, including a second hardening step S81b and a maintenance step S82, is performed between the second printing step S70 and the material removal step S90. Alternatively, a portion of the avoidance step S50 may serve as the post-processing step S80A, or the avoidance step S50 may be omitted.

[0189] Through the second embodiment described above, similar to the first embodiment described above, printing can be appropriately performed on the workpiece W even if it has various three-dimensional shapes. In this embodiment, the three-dimensional printing apparatus 1 sequentially executes the first printing step S40, the first curing step S81a, the second printing step S70, and the second curing step S81b. Therefore, the first printing step S40 and the first curing step S81a can be performed continuously. As a result, since the ink sprayed onto the workpiece W in the first printing step S40 can be cured immediately in the first curing step S81a, image bleeding caused by ink flow on the workpiece W can be reduced. Similarly, the second printing step S70 and the second curing step S81b can be performed continuously. As a result, since the ink sprayed onto the workpiece W in the second printing step S70 can be cured immediately in the second curing step S81b, image bleeding caused by ink flow on the workpiece W can be reduced.

[0190] 3. Variations

[0191] The methods illustrated above can be modified in a variety of ways. Specific modifications applicable to the methods described above are illustrated below. Furthermore, two or more methods arbitrarily selected from the following examples can be appropriately combined without contradiction.

[0192] 3-1. Variation Example 1

[0193] Figure 15 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to Modification Example 1. Modification Example 1 is the same as the first embodiment described above, except that the adjustment step S30 is omitted and the first printing step S40A and the second printing step S70A are performed instead of the first printing step S40 and the second printing step S70A.

[0194] In each of the first printing step S40 and the second printing step S70, the path by which the head 5a is moved by the first robotic arm 3 is adjusted based on the information obtained in the information acquisition step S20. Therefore, even if the support position of the workpiece W implemented by the second robotic arm 4 deviates from the desired position, this adjustment can reduce errors in the relative position and orientation of the head 5a and the workpiece W. Similarly to the first embodiment described above, through the above variation 1, the workpiece W can be appropriately printed even if it has various three-dimensional shapes.

[0195] 3-2. Variation Example 2

[0196] Figure 16 This is a top view of the stereolithography printing apparatus 1A according to Modification Example 2. Except for the number of three imaging units 7, the stereolithography printing apparatus 1A has the same structure as the stereolithography printing apparatus 1 of the first embodiment described above. Specifically, in addition to having an imaging unit 7 for imaging in the Y1 direction, as in the first embodiment, the stereolithography printing apparatus 1A also has an imaging unit 7 for imaging in the Z1 direction and an imaging unit 7 for imaging in the X1 direction.

[0197] Through the above-described Modification 2, similar to the first embodiment described above, printing can be appropriately performed on the workpiece W even if it has various three-dimensional shapes. In Modification 2, since the number of imaging units 7 is greater than that in the first embodiment, it has the advantage of easily improving the detection accuracy of the position and orientation of the workpiece W obtained from the imaging results of the imaging units 7. Here, it is preferable that the workpiece W during printing is located inside the area where the imaging ranges of the imaging devices 7a of these imaging units 7 overlap.

[0198] 3-3. Variation Example 3

[0199] Although the structure of a six-axis vertical multi-axis robotic arm was exemplified as a moving mechanism in the foregoing description, it is not limited to this structure. The moving mechanism only needs to be able to change the relative position and orientation of the liquid nozzle in three dimensions relative to the workpiece. Therefore, the moving mechanism can be, for example, a vertical multi-axis robotic arm other than six axes, or a horizontal multi-axis robotic arm. Furthermore, the robotic arm may have a telescopic mechanism in addition to the joints formed by the rotating mechanism. However, from the viewpoint of balancing the print quality during printing operations with the degrees of freedom of the moving mechanism during non-printing operations, a multi-axis robotic arm with six or more axes is preferred. In addition, a dual-arm robotic arm can be used, in which case one arm can be used as the first robotic arm and the other arm as the second robotic arm.

[0200] 3-4. Variation Example 4

[0201] Although the structure described above illustrates a method of fixing the head relative to the first robotic arm using screws or similar fastening mechanisms, it is not limited to this structure. For example, the head can also be fixed relative to the first robotic arm by gripping it with a gripping mechanism such as a gripper mounted on the end effector of the first robotic arm.

[0202] 3-5. Variation Example 5

[0203] Although the foregoing description illustrates a structure that uses one type of ink for printing, it is not limited to that structure and can also be applied to structures that use two or more types of ink for printing.

[0204] 3-6. Variation Example 6

[0205] The application of the three-dimensional printing apparatus of the present invention is not limited to printing. For example, the three-dimensional printing apparatus that sprays a solution of color material can be used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Furthermore, the three-dimensional printing apparatus that sprays a solution of conductive material can be used as a manufacturing apparatus for forming wiring or electrodes for wiring substrates. In addition, the three-dimensional printing apparatus can also be used as a spray dispenser for applying liquids such as adhesives to workpieces.

[0206] Symbol Explanation

[0207] 1…Stereolithography printing apparatus; 1A…Stereolithography printing apparatus; 2…Base; 2a…Surface; 2b…Exhaust port; 3…First robotic arm; 3a…Arm drive mechanism; 4…Second robotic arm; 4a…Arm drive mechanism; 5…Liquid ejection unit; 5a…Head; 5b…Pressure regulating valve; 5c…Pre-curing light source; 5d…Switching circuit; 5e…Support body; 6…Ink supply unit; 6a…Ink tank; 6b…Supply pipe; 6c…Sub-tank; 6d…Supply pipe; 7…Illumination unit; 7a…Illumination device; 7b…Lighting unit; 8…Maintenance unit; 8a…Unit; 8b…Unit; 9…Placement; 9a…Surface; 10…Curing unit; 10a…Light shielding component; 10b…Light source; 11…Controller ; 11a…Storage circuit; 11b…Processing circuit; 12…Control module; 12a…Timing signal generation circuit; 12b…Power supply circuit; 12c…Control circuit; 12d…Drive signal generation circuit; 13…Computer; 20…Housing; 40…Grappling mechanism; 310…Base; 320…Arm; 321…Arm; 322…Arm; 323…Arm; 324…Arm; 325…Arm; 326…Arm; 330_1…Joint; 330_2…Joint; 330_3…Joint; 330_4…Joint; 330_5…Joint; 330_6…Joint; 410…Base; 420…Arm; CLK…Clock signal; CNG…Switching signal; Com…Driver Signal; D1…output; D2…output; D3…signal; DH…head movement distance; DW…workpiece movement distance; Da…path information; Db…path information; F…nozzle face; LAT…latch signal; LS1…first straight line; LS2…second straight line; LV…imaginary line segment; La…first nozzle array; Lb…second nozzle array; N…nozzle; O1…rotation axis; O2…rotation axis; O3…rotation axis; O4…rotation axis; O5…rotation axis; O6…rotation axis; PD…drive pulse; PTS…timing signal; RI…shooting range; RL…illumination range; RP1…first area; RP2…second area; RR1…action range; RR2…action range; S10…feeding step S11…Holding step; S20…Information acquisition step; S30…Adjustment step; S40…First printing step; S40A…First printing step; S50…Avoidance step; S60…Movement step; S70…Second printing step; S70A…Second printing step; S80…Post-processing step; S80A…Post-processing step; S80B…Post-processing step; S81…Hardening step; S81a…First hardening step; S81b…Second hardening step; S82…Maintenance step; S90…Material removal step; SI…Control signal; Sk1…Control signal; Sk2…Control signal; VBS…Offset potential; VHV…Power supply potential; W…Workpiece; dCom…Waveform specification signal.

Claims

1. A stereolithography apparatus characterized by, A three-dimensional object printing apparatus that performs printing on a three-dimensional workpiece, and has: a photographing device fixed to a base and photographing an object located inside a photographing range; a first robot arm that supports a head having a nozzle that ejects liquid and changes the position and posture of the head; a second robot arm that supports the workpiece and changes the position and posture of the workpiece, In the three-dimensional object printing apparatus, the following steps are performed: a material supply step in which the second robot arm moves the workpiece from outside to inside of the photographing range; a printing step in which, with the workpiece and the head located inside the photographing range, the second robot arm fixes the position and posture of the workpiece, and the head ejects liquid to the workpiece while the first robot arm moves the head relative to the workpiece; an information acquisition step performed between the material supply step and the printing step, in which information about the relative position of the workpiece with respect to the base is acquired based on a photographing result of the photographing device photographed while the second robot arm holds the workpiece.

2. The three-dimensional object printing apparatus according to claim 1, wherein the second robot arm has a gripper mechanism that holds the workpiece in a detachable manner.

3. The three-dimensional object printing apparatus according to claim 2, wherein a placement portion configured to place the workpiece outside the photographing range is further provided, the gripper mechanism receives supply of the workpiece from the placement portion.

4. The three-dimensional object printing apparatus according to claim 1, wherein in the information acquisition step, the head is located outside the photographing range.

5. The three-dimensional object printing apparatus according to claim 1, wherein a maintenance unit that covers the nozzle is further provided, the maintenance unit is located outside the photographing range, in the information acquisition step, the nozzle is covered by the maintenance unit.

6. The three-dimensional object printing apparatus according to claim 5, wherein the maintenance unit is located inside an action range of the first robot arm and outside an action range of the second robot arm.

7. The three-dimensional object printing apparatus according to claim 1, wherein in the printing step, a path in which the first robot arm moves the head is adjusted based on the information acquired in the information acquisition step.

8. The three-dimensional object printing apparatus according to claim 1, wherein an adjustment step that adjusts the position of the workpiece located inside the photographing range is further performed between the information acquisition step and the printing step, in the adjustment step, the action of the second robot arm is controlled based on the information acquired in the information acquisition step.

9. The three-dimensional object printing apparatus according to claim 1, wherein an illumination portion that illuminates the inside of the photographing range is further provided, In the information acquisition step, the illumination section is caused to be lit up, In the printing step, the illumination section is caused to be turned off.

10. The stereoscopic object printing apparatus according to claim 9, wherein a maintenance unit that covers the nozzle is further provided, the maintenance unit is located outside the illumination range of the illumination section.

11. The stereoscopic object printing apparatus according to claim 9 or 10, wherein the head has a nozzle face on which the nozzle is provided, the nozzle face is located outside the illumination range of the illumination section or in a direction toward a back light of light from the illumination section when the illumination section is lit up.

12. The stereoscopic object printing apparatus according to claim 1, wherein in the information acquisition step, at least a part of the first robot arm located inside the photographing range has a color different from that of the workpiece.

13. The stereoscopic object printing apparatus according to claim 1, wherein in the information acquisition step, at least a part of the second robot arm located inside the photographing range has a color different from that of the workpiece.

14. The stereoscopic object printing apparatus according to claim 1, wherein the first robot arm has a first base portion that is fixed to the base, the second robot arm has a second base portion that is fixed to the base, a virtual line segment that links the first base portion and the second base portion passes through the photographing range when viewed from above the base.

15. The stereoscopic object printing apparatus according to claim 1, wherein the liquid ejected from the head has a light hardening property.

Images