Three dimensional object printing apparatus

Abstract

To miniaturize a liquid discharge head.SOLUTION: A three dimensional object printing apparatus 1 includes a head unit 3a having a liquid ejecting head 30 that ejects first liquid, a head unit 3b having a liquid ejecting head 30 that ejects the second liquid, and a robot 2 that moves the head unit 3a with respect to a three dimensional workpiece W in a state in which the head unit 3a is mounted and moves the head unit 3b with respect to the workpiece W in a state in which the head unit 3b is mounted, and the head unit 3a and the head unit 3b are attachable to and detachable from the robot 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a three-dimensional object printing apparatus.

Background Art

[0002] Conventionally, a three-dimensional object printing apparatus that performs printing on the surface of a three-dimensional workpiece by an inkjet method using a robot has been known. For example, Patent Document 1 discloses a three-dimensional printing apparatus having a head capable of discharging a plurality of colors of ink.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, since a liquid discharge head capable of discharging a plurality of colors of ink includes a plurality of nozzles that discharge the plurality of colors of ink respectively, the liquid discharge head itself may be enlarged. For this reason, in a three-dimensional object printing apparatus capable of printing using a plurality of colors of ink, it is desired to reduce the size of the liquid discharge head.

Means for Solving the Problems

[0005] In order to solve the above problems, a three-dimensional object printing apparatus according to the present invention includes a first head unit having a first liquid discharge head that discharges a first liquid, a second head unit having a second liquid discharge head that discharges a second liquid, and a moving mechanism that moves the first head unit with respect to a three-dimensional workpiece in a state where the first head unit is mounted and moves the second head unit with respect to the workpiece in a state where the second head unit is mounted, and the first head unit and the second head unit are detachable from the moving mechanism.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0007] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Also, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless otherwise specifically stated in the following description to limit the present invention.

[0008] Hereinafter, for convenience of explanation, the X-axis, Y-axis, and Z-axis that intersect each other will be used for explanation as appropriate. Further, hereinafter, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y-axis are the Y1 direction and the Y2 direction. Also, the directions opposite to each other along the Z-axis are the Z1 direction and the Z2 direction. The X1 direction is an example of the "first direction".

[0009] Here, the X-axis, Y-axis, and Z-axis correspond to the coordinate axes of the world coordinate system set in the space where the robot 2 described later is installed. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. In the world coordinate system, a base coordinate system based on the position of the base 210 of the robot 2 described later is associated by calibration. Hereinafter, for convenience, a case where the operation of the robot 2 is controlled using the world coordinate system as a robot coordinate system will be exemplified.

[0010] Note that the Z-axis does not have to be a vertical axis. Also, the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, but are not limited thereto and may not be orthogonal. For example, the X-axis, Y-axis, and Z-axis may intersect each other at an angle within the range of 80° or more and 100° or less.

[0011] [1. Embodiment] First, with reference to FIG. 1, an overview of the three-dimensional object printing apparatus 1 according to the present embodiment will be described.

[0012] FIG. 1 is a perspective view showing an outline of the three-dimensional object printing apparatus 1 according to the embodiment of the present invention. The three-dimensional object printing apparatus 1 is an apparatus that performs printing by an inkjet method on a printing area Wa that is a part or all of the surface of a three-dimensional workpiece W.

[0013] The workpiece W has a surface that includes a printing area Wa where an image is to be formed. In the example shown in FIG. 1, the workpiece W is a hemispherical body, and the surface of the workpiece W is a convex hemispherical surface. The workpiece W is supported, for example, by a predetermined mounting table, the hand of a robot other than the robot 2 described later, or a structure such as a conveyor. Note that the size, shape, or mounting posture of the workpiece W is not limited to the example shown in FIG. 1 and is arbitrary. That is, the three-dimensional workpiece W includes planar media such as printing paper.

[0014] The three-dimensional object printing apparatus 1 shown in FIG. 1 includes a robot 2, head units 3a and 3b, holding mechanisms 4a and 4b that are used as placement locations for the head units 3a and 3b respectively, a controller 5 that controls the operation of the robot 2, a pedestal ST, and a connecting member CT. Further, the three-dimensional object printing apparatus 1 includes a computer 7 that will be described with reference to FIG. 2.

[0015] In the example shown in FIG. 1, the head unit 3a is attached to the robot 2, and the head unit 3b is held by the holding mechanism 4b. Hereinafter, the head units 3a and 3b may be collectively referred to as the head unit 3, and the holding mechanisms 4a and 4b may be collectively referred to as the holding mechanism 4. Also, in FIG. 1, the case where the three-dimensional object printing apparatus 1 has two head units 3 is illustrated, but the number of head units 3 is not limited to two. For example, the three-dimensional object printing apparatus 1 may have three or more head units 3. Similarly, the number of holding mechanisms 4 included in the three-dimensional object printing apparatus 1 is not limited to two and may be three or more. Note that it is preferable that the number of holding mechanisms 4 included in the three-dimensional object printing apparatus 1 is the same as the number of head units 3 included in the three-dimensional object printing apparatus 1.

[0016] Also, the robot 2 is an example of a "moving mechanism", the head unit 3a is an example of a "first head unit", and the head unit 3b is an example of a "second head unit". Also, the holding mechanism 4a is an example of a "first holding mechanism", and the holding mechanism 4b is an example of a "second holding mechanism". First, the robot 2 will be described.

[0017] Robot 2 changes the position and orientation of the head unit 3 in the world coordinate system. For example, robot 2 moves the head unit 3 while changing the orientation of the head unit 3 with respect to the three-dimensional workpiece W. In the example shown in FIG. 1, robot 2 is a so-called six-axis vertical articulated robot.

[0018] As shown in FIG. 1, robot 2 includes a base 210, an arm 220, an irradiation unit 260, and joints J1 to J6. Further, robot 2 includes an arm drive mechanism 20 described in FIG. 2, a fixing member 230, a tool changer 240, a heating unit 250, and a heat insulating material 252 described in FIG. 3. Hereinafter, joints J1 to J6 may be collectively referred to as joint J.

[0019] The base 210 is a platform that supports the arm 220. In the example shown in FIG. 1, the base 210 is fixed to the installation surface SF1 of the pedestal ST by screwing or the like. The installation surface SF1 to which the base 210 is fixed is, for example, the surface of the pedestal ST that faces the Z1 direction. The installation surface SF1 to which the base 210 is fixed is not limited to the installation surface SF1 of the pedestal ST, and may be a surface of the floor, wall, ceiling, or a movable cart or the like. That is, the installation surface SF1 to which the base 210 is fixed may be a surface facing any direction.

[0020] The arm 220 is connected to the base 210 and changes the position and orientation of the head unit 3 with respect to the workpiece W. In the example shown in FIG. 1, the arm 220 is a six-axis robot arm that three-dimensionally changes the position and orientation of the head unit 3 with respect to the base 210. Specifically, the arm 220 includes arms 221, 222, 223, 224, 225, and 226, which are connected in this order.

[0021] The arm 221 is connected via a joint J1 so as to be rotatable about a rotation axis O1 with respect to the base 210. The arm 222 is connected via a joint J2 so as to be rotatable about a rotation axis O2 with respect to the arm 221. The arm 223 is connected via a joint J3 so as to be rotatable about a rotation axis O3 with respect to the arm 222. The arm 224 is connected via a joint J4 so as to be rotatable about a rotation axis O4 with respect to the arm 223. The arm 225 is connected via a joint J5 so as to be rotatable about a rotation axis O5 with respect to the arm 224. The arm 226 is connected via a joint J6 so as to be rotatable about a rotation axis O6 with respect to the arm 225.

[0022] Each of the joints J1 to J6 is a mechanism that rotatably connects one of two adjacent members among the base 210 and the arms 221 to 226 to the other.

[0023] Although not shown in FIG. 1, each joint J is provided with a drive mechanism for rotating one of two members connected to each other by each joint J with respect to the other. The assembly of the drive mechanisms for the joints J1 to J6 corresponds to the arm drive mechanism 20 shown in FIG. 2 described later.

[0024] The rotation axis O1 is an axis perpendicular to the installation surface SF1 to which the base 210 is fixed. The rotation axis O2 is an axis perpendicular to the rotation axis O1. The rotation axis O3 is an axis parallel to the rotation axis O2. The rotation axis O4 is an axis perpendicular to the rotation axis O3. The rotation axis O5 is an axis perpendicular to the rotation axis O4. The rotation axis O6 is an axis perpendicular to the rotation axis O5.

[0025] Regarding these rotation axes, the term "perpendicular" includes not only the case where the angle formed by two rotation axes is exactly 90°, but also the case where the angle formed by two rotation axes deviates within a range of about ±5° from 90°. Similarly, the term "parallel" includes not only the case where two rotation axes are exactly parallel, but also the case where one of two rotation axes is inclined within a range of about ±5° with respect to the other. Also, the directions of these rotation axes are not limited to the example shown in FIG. 1.

[0026] Among the arms 221 to 226 of the robot 2, a head unit 3 is mounted on the arm 226 located at the tip of the robot 2 as an end effector. In the example shown in FIG. 1, the head unit 3a is mounted on the arm 226 by a tool changer 240 shown in FIG. 3 and a tool changer 370 described later.

[0027] In addition, an irradiation unit 260 for irradiating energy to cure the ink is attached to the arm 226. An example of the attachment of the irradiation unit 260 will be described with reference to FIG. 3. The irradiation unit 260 irradiates energy such as light, heat, electron beam, or radiation for curing or solidifying the ink on the work W. The irradiation unit 260 may appropriately include optical components such as a lens for adjusting the irradiation direction or irradiation range of the energy.

[0028] Next, an overview of the head unit 3 will be described. Since the configuration of the head unit 3a is the same as that of the head unit 3b, the following description of the head unit 3 applies to both the head units 3a and 3b unless otherwise specified. The details of the head unit 3 will be described with reference to FIGS. 2 and 3.

[0029] The head unit 3 is an assembly having a liquid discharge head 30 for discharging ink toward the work W. For example, the head unit 3 includes a liquid discharge head 30, an ink tank 38 for storing ink, a support 330 for supporting the liquid discharge head 30 and the ink tank 38, and a tool changer 370 connected to the tool changer 240 of the robot 2. Further, the head unit 3 includes a switch circuit 32, a battery 34, and a control module 36 described with reference to FIG. 2, and a self-sealing valve 310, a wiring member 320, and a piping section 350 described with reference to FIG. 3.

[0030] The liquid ejection head 30 included in the head unit 3a is an example of the "first liquid ejection head", and the liquid ejection head 30 included in the head unit 3b is an example of the "second liquid ejection head". Also, the ink ejected from the liquid ejection head 30 included in the head unit 3a is an example of the "first liquid", and the ink ejected from the liquid ejection head 30 included in the head unit 3b is an example of the "second liquid". Further, the ink tank 38 included in the head unit 3a is an example of the "first ink tank", and the ink tank 38 included in the head unit 3b is an example of the "second ink tank". Note that in FIG. 1, the ink tank 38 included in the head unit 3a is hidden by the support 330 included in the head unit 3a and thus not shown.

[0031] The liquid ejection head 30 has, for example, an ejection surface FN and a nozzle row NL in which a plurality of nozzles N opening to the ejection surface FN are arranged to extend in a row in a predetermined direction. Although not shown, the liquid ejection head 30 has, for each nozzle N, a piezoelectric element which is a driving element and a cavity for storing ink. That is, a piezoelectric element and a cavity are provided corresponding to each nozzle N. Here, the piezoelectric element corresponding to each nozzle changes the pressure of the cavity corresponding to the piezoelectric element, thereby ejecting ink from the nozzle N corresponding to the cavity. As a result, droplets which are droplets of ink land on the surface of the workpiece W. Such a liquid ejection head 30 can be obtained, for example, by bonding a plurality of substrates such as a silicon substrate appropriately processed by etching or the like with an adhesive or the like. Note that, as a driving element for ejecting ink from the nozzle N, a heater for heating the ink in the cavity may be used instead of the piezoelectric element.

[0032] In the example shown in FIG. 1, the liquid ejection head 30 has one nozzle row NL, but the liquid ejection head 30 may have a plurality of nozzle rows NL. Regardless of the number of nozzle rows NL included in the liquid ejection head 30, it is preferable that the same type of ink is used for the ink ejected from the plurality of nozzles N included in the liquid ejection head 30.

[0033] The ink is not particularly limited. For example, it may be an aqueous ink in which a coloring material such as a dye or a pigment is dissolved in an aqueous solvent, a curable ink using a curable resin such as an ultraviolet curable type, and a solvent-based ink in which a coloring material such as a dye or a pigment is dissolved in an organic solvent. Among them, the curable ink is preferably used. The curable ink is not particularly limited and may be, for example, any of a thermosetting type, a photocuring type, a radiation curing type, and an electron beam curing type. However, a photocuring type such as an ultraviolet curable type is preferable. When the ink has ultraviolet curability, for example, the above-described irradiation unit 260 is composed of a light emitting element such as an LED (Light Emitting Diode) that irradiates ultraviolet rays.

[0034] Note that the ink is not limited to a solution, and it may be an ink in which a coloring material or the like is dispersed as a dispersed substance in a dispersion medium. Further, the ink is not limited to an ink containing a coloring material. For example, it may be an ink containing conductive particles such as metal particles for forming wiring or the like as a dispersed substance, a clear ink, or a treatment liquid for surface treatment of the work W.

[0035] Here, for example, when the three-dimensional object printing apparatus 1 performs printing using inks of a plurality of colors, inks of different colors are used in the head unit 3a and the head unit 3b. Hereinafter, the ink used in the head unit 3a may be referred to as the first color ink, and the ink used in the head unit 3b may be referred to as the second color ink. For example, when the robot 2 discharges the first color ink onto the workpiece W, the robot 2 moves the head unit 3a relative to the workpiece W with the head unit 3a mounted thereon. Thereby, printing with the first color ink is executed on the workpiece W. Further, when the robot 2 discharges the second color ink onto the workpiece W, the head unit 3a is placed in the holding mechanism 4a and removed from the arm 226, and the head unit 3b held by the holding mechanism 4b is mounted on the arm 226. Then, the robot 2 moves the head unit 3b relative to the workpiece W with the head unit 3b mounted thereon. Thereby, printing with the second color ink is executed on the workpiece W. Thus, in the present embodiment, by replacing the head unit 3 for each color, printing using inks of a plurality of colors can be executed. As a result, in the present embodiment, it is possible to suppress an increase in the size of the liquid discharge head 30 itself as compared with a configuration in which one liquid discharge head discharges inks of a plurality of colors. That is, in the present embodiment, the liquid discharge head 30 can be miniaturized as compared with a configuration in which one liquid discharge head discharges inks of a plurality of colors.

[0036] For example, in a configuration where one liquid ejection head ejects inks of multiple colors, compared to the present embodiment in which one liquid ejection head 30 ejects ink of one color, since the ejection surface FN becomes larger, it is difficult to accurately perform printing on a curved surface or a concave portion. Specifically, in printing on a curved surface, when the ejection surface FN is large, the distance between the nozzle N and the curved surface varies greatly depending on the position of the nozzle N on the ejection surface FN compared to when the ejection surface FN is small. For this reason, when the ejection surface FN is large, the ejection accuracy of the ink varies depending on the position of the nozzle N on the ejection surface FN compared to when the ejection surface FN is small, so it is difficult to accurately perform printing. Also, when the ejection surface FN is large, it becomes difficult to bring the liquid ejection head 30 closer to the bottom of the concave portion compared to when the ejection surface FN is small. For this reason, when the ejection surface FN is large, it is difficult to accurately perform printing on the concave portion compared to when the ejection surface FN is small.

[0037] Similarly, also in a configuration in which a plurality of liquid ejection heads 30 that eject inks of different colors are provided in one head unit, since the area where the ejection surfaces FN of the plurality of liquid ejection heads 30 are located becomes larger, it is difficult to accurately perform printing on a curved surface or a concave portion.

[0038] On the other hand, in the present embodiment, as described above, since the liquid ejection head 30 can be miniaturized, printing on a curved surface or a concave portion can also be accurately performed. Also, in the present embodiment, in printing that ejects droplets of different sizes, the size of the ink droplets ejected from the liquid ejection head 30 of the head unit 3a and the size of the ink droplets ejected from the liquid ejection head 30 of the head unit 3b may be made different. Even in this case, compared to a configuration in which printing that ejects droplets of different sizes is performed with one liquid ejection head, the liquid ejection head 30 can be miniaturized.

[0039] In addition, in the present embodiment, it is assumed that the robot 2 itself automatically executes the replacement of the head unit 3 under the control of the controller 5. For example, the controller 5 determines whether or not the printing on the workpiece W using the ink ejected from the head unit 3a has been completed based on the path information Dp and the printing data Img shown in FIG. 2 described later. Then, when the printing is completed, the controller 5 replaces the head unit 3 mounted on the robot 2 from the head unit 3a to the head unit 3b. Note that the timing of replacing the head unit 3 may be determined by the user. In this case, for example, the user operates the controller 5 at the timing of replacing the head unit 3 to cause the controller 5 to execute the control for replacing the head unit 3.

[0040] Also, in the present embodiment, the holding mechanism 4a is arranged at a position in the Y1 direction relative to the pedestal ST on which the base 210 of the robot 2 is installed, and the holding mechanism 4b is arranged at a position in the Y2 direction relative to the pedestal ST. That is, in the present embodiment, when viewing the robot 2 in a direction parallel to the installation surface SF1 on which the robot 2 is installed and in the X1 direction, which is the direction from the location where the workpiece W is arranged toward the robot 2, the robot 2 is located between the holding mechanism 4a and the holding mechanism 4b. Therefore, in the present embodiment, it is possible to suppress an increase in the movement amount of the robot 2 when mounting the head unit 3 on the robot 2 due to the head unit 3 mounted on the robot 2.

[0041] Also, in this embodiment, the holding mechanisms 4a and 4b are connected to the pedestal ST by the connection member CT. The material of the connection member CT is preferably a rigid body such as a metal material. Since the holding mechanisms 4a and 4b are connected to the pedestal ST by the connection member CT, the positions of the holding mechanisms 4a and 4b with respect to the robot 2 are uniquely determined. Thereby, in this embodiment, when the three-dimensional object printing apparatus 1 replaces the head unit 3 attached to the robot 2, the position of the holding mechanism 4 can be easily specified. As a result, in this embodiment, the replacement of the head unit 3 can be easily performed. Note that the holding mechanisms 4a and 4b may be arranged at an arbitrary position within the movement range of the arm 226 without being connected to the pedestal ST. In this case, for example, after the holding mechanism 4 is arranged, the position of the holding mechanism 4 with respect to the robot 2 may be set in the controller 5 or the like. The setting of the position of the holding mechanism 4 with respect to the robot 2 may be realized by teaching the operation of arranging the head unit 3 attached to the arm 226 on the holding mechanism 4. Alternatively, the controller 5 may cooperate with an imaging device such as a camera that captures the tip of the robot 2 to control the operation of the robot 2 so that the head unit 3 attached to the arm 226 is arranged on the holding mechanism 4, thereby specifying the position of the holding mechanism 4 with respect to the robot 2 and storing the specified position. Even in a configuration where the holding mechanism 4 is not connected to the pedestal ST, when the head unit 3 attached to the robot 2 is replaced, the position of the holding mechanism 4 can be easily specified by setting the position of the holding mechanism 4 with respect to the robot 2 in the controller 5 or the like.

[0042] In addition, in this embodiment, the holding mechanism 4 has a main body member 410 and a support column 420 for supporting the head unit 3 and the like. Further, the holding mechanism 4 is provided with a maintenance unit 46 for maintaining the liquid ejection head 30. The maintenance unit 46 may be regarded as a part of the elements included in the holding mechanism 4, or may be regarded as an element separate from the holding mechanism 4. The maintenance unit 46 has, for example, a cap that covers the liquid ejection head 30 so that the nozzles N are sealed. Further, the maintenance unit 46 may have a discharged ink receiving portion for receiving the ink discharged by the flushing process for discharging the ink in the liquid ejection head 30. Further, the maintenance unit 46 may have one or both of a wiper used for a wiping process for wiping off foreign substances such as paper dust attached in the vicinity of the nozzles N and a tube pump used for a pumping process for sucking the ink, air bubbles, etc. in the liquid ejection head 30. Maintenance includes, for example, at least one of protection of the liquid ejection head 30 by the cap, flushing process, wiping process, and pumping process.

[0043] The element including the maintenance unit 46 provided in the holding mechanism 4a and the maintenance unit 46 provided in the holding mechanism 4b is an example of a "maintenance mechanism". For example, the maintenance unit 46 provided in the holding mechanism 4a maintains the liquid ejection head 30 of the head unit 3a in a state where the head unit 3a is held by the holding mechanism 4a, that is, in a state where the head unit 3a is not mounted on the robot 2. Similarly, the maintenance unit 46 provided in the holding mechanism 4b maintains the liquid ejection head 30 of the head unit 3b in a state where the head unit 3b is held by the holding mechanism 4b, that is, in a state where the head unit 3b is not mounted on the robot 2. Thereby, in this embodiment, maintenance of the liquid ejection head 30 of each head unit 3 can be efficiently performed. The details of the holding mechanism 4 will be described with reference to FIG. 4.

[0044] Next, while referring to FIG. 2, the electrical configuration of the three-dimensional object printing apparatus 1 will be described, including a detailed description of the controller 5.

[0045] FIG. 2 is a block diagram showing the electrical configuration of the three-dimensional object printing apparatus 1 according to the present embodiment. In FIG. 2, among the components of the three-dimensional object printing apparatus 1, the electrical components are shown. As shown in FIG. 2, the three-dimensional object printing apparatus 1 has a computer 7 that is communicably connected to the controller 5 in addition to the components shown in FIG. 1.

[0046] Note that each of the electrical components shown in FIG. 2 may be appropriately divided, a part thereof may be included in other components, or it may be integrally configured with other components. For example, part or all of the functions of the controller 5 may be realized by the computer 7, or may be realized by other external devices such as a PC (personal computer) connected to the controller 5 via a network such as a LAN (Local Area Network) or the Internet. Further, the computer 7 may be regarded as an external element of the three-dimensional object printing apparatus 1.

[0047] The controller 5 has a function of controlling the operation of the robot 2 and a function of generating a signal D3 for synchronizing the ink ejection operation in the head unit 3 with the operation of the robot 2. For example, the controller 5 has a processing circuit 50 and a storage circuit 58.

[0048] The storage circuit 58 stores various programs executed by the processing circuit 50 and various data processed by the processing circuit 50. The storage circuit 58 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). Note that part or all of the storage circuit 58 may be included in the processing circuit 50.

[0049] In this embodiment, the memory circuit 58 stores the program PR1 and the path information Dp. The program PR1 is, for example, a program for the controller 5 to control the operation of the robot 2. The path information Dp is used for controlling the operation of the robot 2 and is information indicating the position and orientation of the liquid ejection head 30 in the path along which the liquid ejection head 30 should move during the execution of the printing operation. The position and orientation of the liquid ejection head 30 are defined, for example, with reference to the tool center point of the robot 2. The tool center point may be, for example, the center of the ejection surface FN which is the tip surface of the liquid ejection head 30, or a position spaced apart from the liquid ejection head 30 in the ink ejection direction. The path information Dp is represented, for example, by the coordinate values of a coordinate system such as a work coordinate system, a base coordinate system, or a world coordinate system based on the position of the work W. For example, the path information Dp is generated by the computer 7 and input from the computer 7 to the memory circuit 58. Note that when the path information Dp is represented using the coordinate values of the work coordinate system, it is used for controlling the operation of the robot 2 after being converted from the coordinate values of the work coordinate system to the coordinate values of the base coordinate system or the world coordinate system.

[0050] The processing circuit 50 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the processing circuit 50 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to the CPU. The processing circuit 50 functions as an element for controlling the operation of the robot 2 and the like by executing the program PR1 stored in the memory circuit 58 and operating according to the program PR1. Specifically, the processing circuit 50 functions as an arm control unit 52, an irradiation control unit 54 that controls the operation of the irradiation unit 260, and a maintenance control unit 56 that controls the operation of the maintenance unit 46 of the holding mechanism 4 by operating according to the program PR1. For example, the arm control unit 52 controls the operation of the arm drive mechanism 20 of the robot 2 based on the path information Dp and generates a signal D3.

[0051] Here, the arm drive mechanism 20 is an aggregate of the drive mechanisms of the joints J1 to J6 described in FIG. 1. For each joint J, it has a motor for driving the joint J of the robot 2 and an encoder for detecting the rotation angle of the joint J of the robot 2.

[0052] The arm control unit 52 performs inverse kinematics calculation, which is an operation to convert the path information Dp into operation amounts such as the rotation angle and rotation speed of each joint J of the robot 2. Also, the arm control unit 52 obtains, as a signal D1 output from each encoder of the arm drive mechanism 20, a signal based on the detection result of the rotation angle of the joint J corresponding to the encoder. Then, the arm control unit 52 outputs a control signal Sk1 based on the signal D1 output from each encoder so that the operation amounts such as the actual rotation angle and rotation speed of each joint J match the result of the inverse kinematics calculation based on the path information Dp. The control signal Sk1 is a signal for controlling the operation of the motor of the arm drive mechanism 20. Here, the control signal Sk1 may be corrected by the arm control unit 52 based on the output from a distance sensor (not shown) as necessary.

[0053] Also, the arm control unit 52 generates a signal D3 based on a signal D1 output from at least one of the plurality of encoders of the arm drive mechanism 20. For example, the arm control unit 52 generates, as the signal D3, a trigger signal including a pulse at a timing when the signal D1 output from one of the plurality of encoders becomes a predetermined value. The signal D3 is transmitted from the controller 5 to the head unit 3a mounted on the robot 2 among the head units 3a and 3b.

[0054] The head unit 3 includes, in addition to the liquid ejection head 30 shown in FIG. 1, a switch circuit 32, a control module 36, and a battery 34 that stores electric power to be supplied to the switch circuit 32 and the control module 36. The elements including the control circuit 362, the drive signal generation circuit 364, and the switch circuit 32 included in the head unit 3a are an example of a "first drive circuit". Also, the elements including the control circuit 362, the drive signal generation circuit 364, and the switch circuit 32 included in the head unit 3b are an example of a "second drive circuit". Further, the battery 34 included in the head unit 3a is an example of a "first battery", and the battery 34 included in the head unit 3b is an example of a "second battery".

[0055] The control module 36 is a circuit that controls the ink ejection operation of the liquid ejection head 30 based on the signal D3 output from the controller 5 and the print data Img from the computer 7. The print data Img is information indicating an image to be printed on the workpiece W in each of a plurality of paths indicated by the path information Dp. The control module 36 includes a timing signal generation circuit 360, a control circuit 362, and a drive signal generation circuit 364.

[0056] The timing signal generation circuit 360 generates a timing signal PTS based on the signal D3. The timing signal generation circuit 360 is composed of, for example, a timer that starts generating the timing signal PTS upon detection of the signal D3.

[0057] The control circuit 362 generates, for example, a control signal SI, a waveform specification signal dCom, a latch signal LAT, a clock signal CLK, and a change signal CNG. Then, the control circuit 362 outputs the control signal SI, the latch signal LAT, the clock signal CLK, and the change signal CNG to the switch circuit 32 in synchronization with, for example, the timing signal PTS, and outputs the waveform specification signal dCom to the drive signal generation circuit 364.

[0058] The control signal SI is a digital signal for specifying the operating state of each driving element included in the liquid ejection head 30. Specifically, the control signal SI is a signal for specifying whether to supply a driving signal Com, which will be described later, to each driving element based on the print data Img. By this specification, for example, it is specified whether to eject ink from the nozzles corresponding to the respective driving elements, or the amount of ink ejected from the nozzles corresponding to the respective driving elements. The waveform specifying signal dCom is a digital signal for defining the waveform of the driving signal Com. The latch signal LAT and the change signal CNG are signals for defining the ejection timing of ink from the nozzles corresponding to the respective driving elements by defining the driving timing of the respective driving elements in combination with the control signal SI. The clock signal CLK is a reference clock signal synchronized with the timing signal PTS.

[0059] Here, the control circuit 362 includes, for example, a processor such as one or more CPUs. Note that the control circuit 362 may include a programmable logic device such as an FPGA instead of or in addition to the CPU.

[0060] The drive signal generation circuit 364 is a circuit that generates a drive signal Com for driving each drive element included in the liquid ejection head 30. Specifically, the drive signal generation circuit 364 includes, for example, a DAC (Digital Analog Converter) and an amplifier circuit. In the drive signal generation circuit 364, the waveform specifying signal dCom supplied from the control circuit 362 is converted from a digital signal to an analog signal by the DAC, and the converted analog signal is amplified by the amplifier circuit to generate the drive signal Com. Here, among the waveforms included in the drive signal Com, the signal of the waveform actually supplied to the drive element is the drive pulse PD. The drive pulse PD is supplied from the drive signal generation circuit 364 to the drive element via the switch circuit 32. The drive pulse PD supplied by the switch circuit 32 included in the head unit 3a is an example of a "first drive signal", and the drive pulse PD supplied by the switch circuit 32 included in the head unit 3b is an example of a "second drive signal".

[0061] Here, the switch circuit 32 is a circuit including a switching element that switches whether to supply at least a part of the waveform included in the drive signal Com as a drive pulse PD based on the control signal SI.

[0062] The battery 34 receives power supply from a commercial power supply (not shown) and stores the power to be supplied to the switch circuit 32 and the control module 36. Further, the battery 34 generates various potentials such as a power supply potential, and supplies the generated various potentials to each part of the switch circuit 32 and the control module 36 as appropriate.

[0063] The computer 7 has a function of generating path information Dp, a function of supplying information such as the path information Dp to the controller 5, and a function of supplying information such as print data Img to the control module 36. For example, the computer 7 has a processing circuit 70 configured in the same manner as the processing circuit 50 of the controller 5 described above, and a storage circuit 78 configured in the same manner as the storage circuit 58 of the controller 5. The processing circuit 70 functions as a transmission control unit 72 and a generation unit 74 by operating according to a program (not shown) stored in the storage circuit 78, for example. For example, the generation unit 74 generates path information Dp based on work information indicating the position and shape of the work W, and supplies the generated path information Dp to the controller 5.

[0064] Also, for example, the transmission control unit 72 transmits print data Img to the control circuit 362 of the head unit 3a mounted on the robot 2 and the control circuit 362 of the head unit 3b held by the holding mechanism 4a. That is, the transmission control unit 72 transmits print data Img to the control module 36 of the head unit 3b even when the head unit 3b is not mounted on the robot 2. Then, when the head unit 3a is mounted on the robot 2, the control module 36 of the head unit 3b supplies the drive signal Com to the liquid ejection head 30 of the head unit 3b based on the print data Img at a timing based on the detection timing of the signal D3. The transmission control unit 72 transmits the print data Img to the control circuit 362 by wire or wirelessly.

[0065] As described above, in this embodiment, since the print data Img is transmitted to the control module 36 of the head unit 3b not mounted on the robot 2, the throughput from when the head unit 3b is mounted on the robot 2 until the drive signal Com is supplied to the liquid ejection head 30 can be improved. Further, the transmission control unit 72 may transmit the print data Img to the control module 36 of each head unit 3 before printing starts. Note that the transmission control unit 72 may transmit the print data Img only to the control circuit 362 of the head unit 3a mounted on the robot 2 among the control circuit 362 of the head unit 3a mounted on the robot 2 and the control circuit 362 of the head unit 3b held by the holding mechanism 4a. The transmission control unit 72 is an example of the "data transmission unit".

[0066] The computer 7 is, for example, a PC. Further, the computer 7 may have a function as a user interface of the three-dimensional object printing apparatus 1. For example, the computer 7 may have an input device such as a keyboard or a mouse that receives operations from the user, or a display device such as a liquid crystal panel that displays information necessary for generating the path information Dp.

[0067] As described above, in this embodiment, the operation of the robot 2 is controlled based on the path information Dp, and the operation of the liquid ejection head 30 of the head unit 3a mounted on the robot 2 is controlled based on the print data Img and the signal D3, whereby the printing operation is performed. For example, in the printing operation, while the robot 2 changes the position and posture of the liquid ejection head 30 based on the path information Dp, the liquid ejection head 30 ejects ink toward the workpiece W at an appropriate timing based on the print data Img and the signal D3. Thereby, an image based on the print data Img is formed on the workpiece W.

[0068] Also, in the present embodiment, by improving the accuracy of mounting the plurality of head units 3 on the robot 2, regardless of the head units 3a and 3b, the paths along which the liquid ejection head 30 should move during the execution of the printing operation can be made substantially the same. Therefore, in the present embodiment, for example, the path information Dp used when moving the head unit 3a mounted on the robot 2 with respect to the work W can be diverted to the path information Dp used when moving the head unit 3b mounted on the robot 2 with respect to the work W. For example, in the present embodiment, the common path information Dp can be used for both the head unit 3a and the head unit 3b. For this reason, in the present embodiment, compared with the case where the path information Dp is generated from scratch for each head unit 3, the preparation for controlling the operation of the robot 2 can be facilitated. Also, by using the common path information Dp for both the head unit 3a and the head unit 3b, it becomes easy to adjust the deviation of the landing position of the ink. When the ink ejected from the liquid ejection head 30 during the execution of the printing operation deviates from the target landing position and lands on the work W due to the operation of the robot 2 or mechanical tolerances or the like. By using the common path information Dp for both the head unit 3a and the head unit 3b, the trajectories along which the liquid ejection head 30 moves during the execution of the printing operation become substantially the same. For this reason, the correction value for correcting the deviation of the landing position that occurred during the execution of the printing operation using the head unit 3a can be diverted to the case of executing the printing operation using the head unit 3b. Further, by measuring the deviation of the landing position that occurs between the head unit 3a and the head unit 3b, a correction value considering the operation of the robot 2 or mechanical tolerances or the like can be generated. Thereby, it becomes easy to adjust the deviation of the landing position that occurs between the head unit 3a and the head unit 3b.

[0069] Next, while referring to FIG. 3, the schematic structure of the head unit 3 will be described.

[0070] FIG. 3 is an explanatory view for explaining the schematic structure of the head unit 3. Hereinafter, for convenience of explanation, the a-axis, b-axis, and c-axis that intersect each other will be used for explanation as appropriate. Further, hereinafter, one direction along the a-axis is the a1 direction, and the direction opposite to the a1 direction is the a2 direction. Similarly, the directions opposite to each other along the b-axis are the b1 direction and the b2 direction. Further, the directions opposite to each other along the c-axis are the c1 direction and the c2 direction.

[0071] Here, the a-axis, b-axis, and c-axis correspond to the coordinate axes of the tool coordinate system set in the head unit 3, and the relative position and attitude relationship with the world coordinate system or the robot coordinate system change due to the operation of the robot 2. In the example shown in FIG. 3, when the head unit 3 is attached to the robot 2, the c-axis is an axis parallel to the rotation axis O6 described in FIG. 1. Note that the a-axis, b-axis, and c-axis are typically orthogonal to each other, but are not limited thereto, and may intersect at an angle within a range of 80° or more and 100° or less, for example. Note that the tool coordinate system and the base coordinate system or the robot coordinate system are associated with each other by calibration.

[0072] In FIG. 3, the structure of the head unit 3 when viewed from the b2 direction is schematically shown. Note that the "mounted state" in FIG. 3 indicates a state where the head unit 3 is mounted on the robot 2, and the "non-mounted state" in FIG. 3 indicates a state where the head unit 3 is removed from the robot 2. When the head unit 3 is mounted on the robot 2, the convex portions Cax and Cd of the tool changer 240 of the robot 2 are inserted into the concave portions Hax and Hd of the tool changer 370, respectively. The convex portion Cax and the concave portion Hax are used for alignment, and the convex portion Cd and the concave portion Hd are used to align the orientation of the head unit 3 with respect to the arm 226 in a predetermined direction. By inserting the convex portions Cax and Cd into the concave portions Hax and Hd, respectively, the mounting accuracy of the plurality of head units 3 on the robot 2 can be improved.

[0073] Incidentally, the tool changer 370 of the head unit 3 may be attached to the tool changer 240 of the robot 2 via an adapter. That is, the attachment of the head unit 3 to the robot 2 also includes the indirect attachment of the head unit 3 to the robot 2.

[0074] In FIG. 3, the structure of the head unit 3 is described, including the description of the mechanism for attaching the head unit 3 to the robot 2. First, the heat insulating material 252, the fixing member 230, the tool changer 240, etc. provided on the robot 2 will be described.

[0075] A heat insulating material 252 is connected to the arm 226 of the robot 2. A fixing member 230 to which a heating unit 250 and an irradiation unit 260 are attached is connected to the heat insulating material 252. The heating unit 250 is an example of the "first heating unit". The fixing member 230 has, for example, a first fixing portion 231 into which the heating unit 250 is inserted and connected to the heat insulating material 252, and a second fixing portion 232 to which the irradiation unit 260 is attached. The second fixing portion 232 is provided so as to project in a direction away from the arm 226 along the rotation axis O6, for example, from the end of the first fixing portion 231. In the example shown in FIG. 3, the second fixing portion 232 has planes SF2 and SF3 perpendicular to the a-axis when the head unit 3 is attached to the arm 226. And the irradiation unit 260 is attached to the plane SF2 near the end far from the arm 226 among the ends in the direction along the rotation axis O6 of the second fixing portion 232. Incidentally, the irradiation unit 260 may be attached to the plane SF3 of the second fixing portion 232.

[0076] The heating unit 250 has, for example, a heater and a thermocouple. For example, the temperature of the heater included in the heating unit 250 is controlled by a controller 5 or the like based on the temperature measured by the thermocouple included in the heating unit 250. In FIG. 3, the description of the wiring through which control signals and the like for controlling the heating unit 250 and the irradiation unit 260 are supplied is omitted. A tool changer 240 that can be attached to and detached from the tool changer 370 of the head unit 3 is connected to the first fixing portion 231 of the fixing member 230.

[0077] The heat insulating material 252 is a member made of a material such as a resin material with excellent heat insulating properties. Further, the materials of the fixing member 230 and the tool changer 240 are rigid bodies such as metal materials with good thermal conductivity, for example. That is, the thermal conductivity of the heat insulating material 252 is smaller than the thermal conductivity of the fixing member 230 and the thermal conductivity of the tool changer 240. As shown in FIG. 1, in the present embodiment, in the direction along the rotation axis O6, the heat insulating material 252 is located between the arm 226 and the first fixing portion 231 of the fixing member 230, and the first fixing portion 231 is located between the heat insulating material 252 and the tool changer 240. For this reason, in the present embodiment, while suppressing the heat from the heater included in the heating portion 250 from being transmitted to the arm 226, the heat from the heater included in the heating portion 250 can be efficiently transmitted to the tool changer 240. Note that the thermal conductivity of the second fixing portion 232 of the fixing member 230 may be smaller than the thermal conductivity of the first fixing portion 231.

[0078] Further, in the present embodiment, since the irradiation unit 260 is fixed to the arm 226 via the fixing member 230, when the arm 226 rotates around the rotation axis O6 with respect to the arm 225, it rotates together with the arm 226.

[0079] Further, in the present embodiment, since the heating unit 250 and the irradiation unit 260 are provided in the robot 2, even when the head unit 3 is replaced, wiring for supplying control signals and the like for controlling the heating unit 250 and the irradiation unit 260 does not need to be disconnected from the heating unit 250 and the irradiation unit 260. For example, since the irradiation unit 260 has a high output, when disconnecting the wiring to which power is supplied, the configuration of the disconnection part of the wiring may become complicated. In the present embodiment, since it is not necessary to disconnect the wiring electrically connected to the irradiation unit 260, it is possible to suppress the complication of the configuration around the irradiation unit 260. Similarly, in the present embodiment, it is possible to suppress the complication of the configuration around the heating unit 250. Focusing on the accuracy of temperature measurement of the thermocouple included in the heating unit 250, it is preferable that the heating unit 250 is provided in the robot 2 rather than in the head unit 3. For example, in a configuration where the heating unit 250 is provided in the head unit 3, since there is no part for disconnecting the wiring electrically connected to the heating unit 250, it is possible to suppress the deterioration of the signal from the thermocouple included in the heating unit 250.

[0080] Next, the head unit 3 will be described.

[0081] The head unit 3 includes a liquid discharge head 30, a switch circuit 32, a battery 34, a control module 36, an ink tank 38, a self-sealing valve 310, a wiring member 320, a support 330, a piping part 350, and a tool changer 370. The liquid discharge head 30, the switch circuit 32, the battery 34, the control module 36, the ink tank 38, and the self-sealing valve 310 are attached to the support 330.

[0082] For example, the support 330 includes a first support portion 331 having a surface SF4 facing the c1 direction and a surface SF5 facing the c2 direction, a second support portion 332 having a surface SF6 facing the a2 direction and a surface SF7 facing the a1 direction, a third support portion 333, and a fourth support portion 334. The first support portion 331 is provided so as to protrude in the a1 direction from the second support portion 332. On the surface SF4 of the first support portion 331, a battery 34, a control module 36, and an ink tank 38 are attached, and a self-sealing valve 310 is attached to the surface SF5 of the first support portion 331. Further, a liquid ejection head 30 is attached to the surface SF7 near the end portion in the c2 direction of the second support portion 332. The second support portion 332 is connected to the tool changer 370 via the third support portion 333 and the fourth support portion 334. For example, the fourth support portion 334 is connected to the tool changer 370, the third support portion 333 is connected to the fourth support portion 334, and the second support portion 332 is connected to the third support portion 333. Although details will be described with reference to FIG. 4, in the present embodiment, the head unit 3 is supported by the holding mechanism 4 by the first support portion 331 and the third support portion 333 being supported by the holding mechanism 4.

[0083] The materials of the support 330 and the tool changer 370 are rigid bodies such as metal materials having good thermal conductivity, for example. That is, the thermal conductivity of the support 330 and the thermal conductivity of the tool changer 370 are greater than the thermal conductivity of the heat insulating material 252. Accordingly, in the present embodiment, the heat from the heater included in the heating unit 250 can be efficiently transmitted to the liquid ejection head 30 and the ink tank 38 via the tool changer 240, the tool changer 370, and the support 330. As a result, in the present embodiment, the ink in the liquid ejection head 30 and the ink in the ink tank 38 included in the head unit 3 attached to the robot 2 can be heated.

[0084] Ink is supplied from the ink tank 38 to the liquid ejection head 30 through the piping section 350. For example, the liquid ejection head 30 has a reservoir 302 that stores the ink supplied from the ink tank 38. Note that the capacity of the ink that the ink tank 38 can store is larger than the capacity of the ink that the reservoir 302 can store.

[0085] Also, a self-sealing valve 310 is provided in the piping section 350 that connects the liquid ejection head 30 and the ink tank 38. The self-sealing valve 310 is a valve mechanism that opens and closes according to the pressure of the ink in the reservoir 302 that the liquid ejection head 30 has. For example, even if the posture of the head unit 3 changes, the pressure of the ink in the reservoir 302 that the liquid ejection head 30 has is maintained at a negative pressure within a predetermined range by opening and closing the self-sealing valve 310. In this way, the self-sealing valve 310 adjusts the pressure applied to the ink supplied from the ink tank 38 to the liquid ejection head 30.

[0086] Also, in the present embodiment, as shown in FIG. 3, the self-sealing valve 310 is attached to the surface SF5 of the first support portion 331 so that the longitudinal direction of the self-sealing valve 310 is parallel to the direction along the a-axis. In this case, compared with the configuration in which the self-sealing valve 310 is attached to the support 330 so that the longitudinal direction of the self-sealing valve 310 is parallel to the direction along the c-axis, the head unit 3 can be miniaturized. Note that the self-sealing valve 310 that the head unit 3a has is an example of the "first pressure adjustment unit", and the self-sealing valve 310 that the head unit 3b has is an example of the "second pressure adjustment unit".

[0087] Note that the pressure adjustment unit that adjusts the pressure applied to the ink supplied from the ink tank 38 to the liquid ejection head 30 is not limited to the self-sealing valve 310. For example, the head unit 3 may have, as the pressure adjustment unit, a mechanism that includes an air pressurization mechanism for pressurizing the ink tank 38 and the self-sealing valve 310. Alternatively, the head unit 3 may have, as the pressure adjustment unit, a back pressure adjustment mechanism different from the air pressurization mechanism and the self-sealing valve 310. Alternatively, the back pressure of the ink in the ink tank 38 may be maintained at a negative pressure by putting a sponge or the like into the ink tank 38.

[0088] The switch circuit 32 is connected to the battery 34 and the control module 36 by a wiring member 320. For example, one end of the wiring member 320 is connected to the battery 34 and the control module 36, and the other end of the wiring member 320 is connected to the liquid ejection head 30 and the switch circuit 32. The wiring member 320 is, for example, a flexible flat cable. Note that the wiring member 320 is not limited to a flexible flat cable. For example, the wiring member 320 may be a flexible printed circuit board.

[0089] Here, in the present embodiment, when the three-dimensional object printing apparatus 1 performs printing on the workpiece W, the operation of the robot 2 is controlled so that the moving direction of the liquid ejection head 30 becomes the a1 direction. Therefore, the a1 direction corresponds to the front in the moving direction of the liquid ejection head 30, and the a2 direction corresponds to the rear in the moving direction of the liquid ejection head 30. As shown in Fig. 3, the irradiation unit 260 is fixed to the arm 226 via the fixing member 230 so as to be positioned in the a2 direction with respect to the liquid ejection head 30 of the head unit 3 mounted on the robot 2. That is, the irradiation unit 260 is positioned behind the liquid ejection head 30 in the moving direction of the liquid ejection head 30. For this reason, in the present embodiment, the irradiation unit 260 can irradiate energy onto the ink that has just landed on the workpiece W from the liquid ejection head 30.

[0090] Also, in the present embodiment, the ink tank 38 is positioned in front of the liquid ejection head 30 in the moving direction of the liquid ejection head 30. Thereby, in the present embodiment, the irradiation unit 260 can be easily arranged behind the liquid ejection head 30 in the moving direction of the liquid ejection head 30.

[0091] Also, in this embodiment, since the head unit 3 has the ink tank 38, it is possible to suppress the complication of the arrangement of the piping portion 350 for supplying ink to the liquid discharge head 30. For example, in a configuration where the head unit 3 does not have the ink tank 38, it is necessary to arrange a tube or the like for transporting ink from the outside of the head unit 3 to the liquid discharge head 30. Since the head unit 3 moves relative to the workpiece W, in a configuration having a tube for transporting ink from the outside of the head unit 3 to the liquid discharge head 30, issues such as how to attach the tube and where to install it become problems. In addition, there is a possibility that the operating range of the robot 2 is restricted by a tube for transporting ink from the outside of the head unit 3 to the liquid discharge head 30. In this embodiment, since a tube for transporting ink from the outside of the head unit 3 to the liquid discharge head 30 is not required, the configuration of the three-dimensional object printing apparatus 1 can be simplified, and it is possible to suppress the restriction of the operating range of the robot 2.

[0092] Also, in this embodiment, in a path along a predetermined direction when viewing the workpiece W from the Z1 direction, one-way printing is executed in which printing is performed in only one direction, either the forward path or the return path, of the path along the predetermined direction. Note that reciprocating printing in which printing is performed in both the forward and return paths of the path along the predetermined direction may be executed. In reciprocating printing, when switching from printing in one of the forward path printing and the return path printing to the other, the arm 226 may be rotated 180 degrees so that the irradiation unit 260 is positioned behind the liquid discharge head 30 in the moving direction of the liquid discharge head 30 with respect to the liquid discharge head 30. At this time, in reciprocating printing, it is desirable that the wiring for supplying a control signal or the like for controlling the heating unit 250 and the irradiation unit 260 is arranged so that the arm 226 can be rotated 180 degrees. In reciprocating printing, it is not necessary to rotate the arm 226 by 180 degrees when switching from printing in one direction (forward pass) to printing in the other direction (return pass). There are cases where the printing area in the forward pass overlaps with the printing area in the return pass, or the printing area in the forward pass is included in the irradiation area where energy is irradiated from the irradiation unit 260 during printing in the return pass. At this time, by irradiating the irradiation unit 260 without rotating the arm 226 by 180 degrees during printing in the return pass, energy can be irradiated onto the ink that has landed on the workpiece W during printing in the forward pass.

[0093] Next, with reference to FIG. 4, the configuration of the holding mechanism 4 will be described, including the parts of the head unit 3 not described in FIG. 3.

[0094] FIG. 4 is an explanatory diagram for explaining the configuration of the holding mechanism 4. In FIG. 4, the description of the wiring member 320 shown in FIG. 3 is omitted. First, the parts of the head unit 3 not described in FIG. 3 will be described.

[0095] The tool changer 370 of the head unit 3 is provided with a concave portion Hax at the center and a plurality of concave portions Hd around the concave portion Hax when viewed from the Z1 direction.

[0096] The ink tank 38 has, for example, a supply port 382 for supplying ink to the ink tank 38, an adjustment port 384 for taking in air to adjust the internal pressure of the ink tank 38, and a discharge port 386 for discharging ink from the ink tank 38. Further, the pipe portion 350 described in FIG. 3 has a tube 352 and a connection portion 354 that communicates with the self-sealing valve 310. For example, the tube 352 connects the discharge port 386 and the connection portion 354. Thereby, the ink tank 38 is connected to the self-sealing valve 310.

[0097] In a state where ink is not being supplied to the ink tank 38, the supply port 382 may be covered with a lid so that ink does not leak from the ink tank 38. Alternatively, the supply port 382 may be formed with a small opening so that ink does not leak from the ink tank 38.

[0098] Also, the ink supply to the ink tank 38 may be performed manually. Alternatively, as shown in FIG. 7 described later, the three-dimensional object printing apparatus 1 may include a liquid supply mechanism 48 that supplies ink to the ink tank 38.

[0099] Next, the configuration of the holding mechanism 4 will be described.

[0100] As described with reference to FIG. 1, the holding mechanism 4 includes a main body member 410, a support column 420, and a maintenance unit 46. The main body member 410 includes a first portion 411 connected to the pedestal ST shown in FIG. 1, a second portion 412 where the maintenance unit 46 is disposed, a third portion 413 that supports the first support portion 331 of the head unit 3, and a fourth portion 414 that supports the third support portion 333 of the head unit 3. The support column 420 includes a plurality of support columns 421, a plurality of support columns 422, a plurality of support columns 423, and a plurality of support columns 424. The plurality of support columns 421 support the second portion 412 at intervals in the Z1 direction with respect to the first portion 411, and the plurality of support columns 422 support the third portion 413 at intervals in the Z1 direction with respect to the second portion 412. Also, the plurality of support columns 423 support the fourth portion 414 at intervals in the Z1 direction with respect to the third portion 413, and the plurality of support columns 424 support the maintenance unit 46 at intervals in the Z1 direction with respect to the second portion 412. Note that the maintenance unit 46 is located between the second portion 412 and the third portion 413 in the direction along the Z axis.

[0101] In the example shown in FIG. 4, the first portion 411 and the second portion 412 are formed in a plate shape having a plane perpendicular to the Z-axis. Further, the third portion 413 has an opening penetrating in the direction along the Z-axis at the center. Furthermore, the third portion 413 has an opening penetrating in the direction along the Z-axis in the portion where the second support portion 332 of the head unit 3 is located. Also, when the head unit 3 is held by the holding mechanism 4 and viewed from the Z1 direction, the fourth portion 414 is arranged so as not to overlap with the second support portion 332 of the head unit 3 and partially overlap with the third support portion 333 of the head unit 3.

[0102] Note that the configuration of the head unit 3 is not limited to the examples shown in FIGS. 3 and 4. Similarly, the configuration of the holding mechanism 4 is not limited to the example shown in FIG. 4. For example, the head unit 3 may be formed such that in the direction along the c-axis, the third support portion 333 of the support 330 is at the same position as the first support portion 331. In this case, as the holding mechanism 4 that holds the head unit 3 formed such that the third support portion 333 of the support 330 is at the same position as the first support portion 331, for example, a configuration in which the fourth portion 414 and the plurality of support columns 423 are omitted from the holding mechanism 4 shown in FIG. 4 is adopted.

[0103] As described above, in the present embodiment, the three-dimensional object printing apparatus 1 includes a head unit 3a having a liquid discharge head 30 that discharges a first liquid, a head unit 3b having a liquid discharge head 30 that discharges a second liquid, and a robot 2 that moves the head unit 3a with respect to a three-dimensional workpiece W in a state where the head unit 3a is mounted and moves the head unit 3b with respect to the workpiece W in a state where the head unit 3b is mounted. The head unit 3a and the head unit 3b are detachable from the robot 2.

[0104] Thus, in the present embodiment, the first liquid and the second liquid are discharged onto the workpiece W by using the detachable head units 3a and 3b for the robot 2. That is, in the present embodiment, the head unit 3 attached to the robot 2 is replaced according to the liquid to be discharged onto the workpiece W. Therefore, in the present embodiment, the head unit 3 can be miniaturized as compared with the configuration in which the discharge of the first liquid and the second liquid is performed by one head unit. As a result, in the present embodiment, printing on a curved surface can be accurately executed as compared with the configuration in which the discharge of the first liquid and the second liquid is performed by one head unit.

[0105] Further, in the present embodiment, the head unit 3a has an ink tank 38 in which the first liquid is stored, and the head unit 3b has an ink tank 38 in which the second liquid is stored. Thus, in the present embodiment, since the head unit 3 has the ink tank 38, a tube for transporting ink from the outside of the head unit 3 to the liquid discharge head 30 is not required. Therefore, in the present embodiment, the configuration of the three-dimensional object printing apparatus 1 can be simplified, and it is possible to suppress the operation range of the robot 2 from being restricted by the tube.

[0106] Further, in the present embodiment, the head unit 3a has a self-sealing valve 310 that adjusts the pressure applied to the first liquid supplied from the ink tank 38 to the liquid discharge head 30. The head unit 3b has a self-sealing valve 310 that adjusts the pressure applied to the second liquid supplied from the ink tank 38 to the liquid discharge head 30. Thus, in the present embodiment, each head unit 3 has the self-sealing valve 310. Therefore, in the present embodiment, even when the head unit 3 attached to the robot 2 is replaced, the pressure related to the liquid can be adjusted in the head unit 3 attached to the robot 2. Therefore, in the present embodiment, even when the posture of the head unit 3 attached to the robot 2 changes, the pressure related to the liquid can be adjusted in the head unit 3 attached to the robot 2, so that the liquid can be appropriately discharged from the liquid discharge head 30 onto the workpiece W.

[0107] Further, in the present embodiment, the robot 2 is provided separately from the head units 3a and 3b, and has an irradiation unit 260 that irradiates energy for curing the first liquid and the second liquid. Thus, in the present embodiment, since the irradiation unit 260 is provided in the robot 2, even when the head unit 3 is replaced, it is not necessary to disconnect the wiring electrically connected to the irradiation unit 260. Therefore, in the present embodiment, it is possible to suppress the complication of the configuration around the irradiation unit 260 as compared with a configuration in which it is necessary to disconnect the wiring electrically connected to the irradiation unit 260 when replacing the head unit 3.

[0108] Further, in the present embodiment, the robot 2 is provided separately from the head units 3a and 3b, and has a heating unit 250 that heats the liquid. The heating unit 250 heats the first liquid in a state where the head unit 3a is mounted. Thus, in the present embodiment, since the heating unit 250 is provided in the robot 2, even when the head unit 3 is replaced, it is not necessary to disconnect the wiring electrically connected to the heating unit 250. Therefore, in the present embodiment, it is possible to suppress the complication of the configuration around the heating unit 250 as compared with a configuration in which it is necessary to disconnect the wiring electrically connected to the heating unit 250 when replacing the head unit 3.

[0109] Further, in the present embodiment, the head unit 3a includes a control module 36 that generates a drive signal Com for driving the liquid discharge head 30, and a battery 34 that stores electric power to be supplied to the control module 36. The head unit 3b includes a control module 36 that generates a drive signal Com for driving the liquid discharge head 30, and a battery 34 that stores electric power to be supplied to the control module 36.

[0110] As described above, in the present embodiment, since each head unit 3 has the control module 36 and the battery 34, it is possible to suppress the complication of the configuration of the three-dimensional object printing apparatus 1. For example, in a configuration where the control module 36 is provided in the robot 2, a part of the wiring connecting the control module 36 and the liquid discharge head 30 is arranged in the robot 2, and the other part of the wiring is arranged in the head unit 3. In this case, the wiring arranged in the head unit 3 needs to be detachably connected to the wiring arranged in the robot 2 because the head unit 3 is detachable from the robot 2. Therefore, in the configuration where the control module 36 is provided in the robot 2, the connection portion between the wiring arranged in the robot 2 and the wiring arranged in the head unit 3 may become complicated. On the other hand, in the present embodiment, since each head unit 3 has the control module 36, it is not necessary to configure the wiring connecting the control module 36 and the liquid discharge head 30 to be detachable. Further, in the present embodiment, since each head unit 3 has the control module 36 and the battery 34, it is not necessary to configure the wiring connecting the battery 34 and the control module 36 to be detachable. As a result, in the present embodiment, the configuration of the three-dimensional object printing apparatus 1 can be simplified.

[0111] Further, in the present embodiment, the three-dimensional object printing apparatus 1 further includes a transmission control unit 72 that transmits the print data Img to the control module 36 of the head unit 3a and the control module 36 of the head unit 3b. The transmission control unit 72 transmits the print data Img to the control module 36 of the head unit 3b in a state where the head unit 3b is not attached to the robot 2. The control module 36 of the head unit 3b supplies the drive signal Com to the liquid discharge head 30 based on the print data Img when the head unit 3b is attached to the robot 2. As described above, in the present embodiment, since the print data Img is also transmitted to the control module 36 of the head unit 3b that is not attached to the robot 2, the throughput from when the head unit 3b is attached to the robot 2 until the drive signal Com is supplied to the liquid discharge head 30 can be improved.

[0112] Further, in the present embodiment, the three-dimensional object printing apparatus 1 further includes a maintenance unit 46 that maintains the liquid ejection head 30 of the head unit 3a and the liquid ejection head 30 of the head unit 3b. The maintenance unit 46 maintains the liquid ejection head 30 of the head unit 3a in a state where the head unit 3a is not attached to the robot 2, and maintains the liquid ejection head 30 of the head unit 3b in a state where the head unit 3b is not attached to the robot 2. Thus, in the present embodiment, since the liquid ejection head 30 of the head unit 3 not attached to the robot 2 can be maintained, the maintenance of the liquid ejection head 30 can be efficiently performed.

[0113] Further, in the present embodiment, the three-dimensional object printing apparatus 1 further includes a holding mechanism 4a that holds the head unit 3a and a holding mechanism 4b that holds the head unit 3b. When looking at the robot 2 in the X1 direction, which is a direction parallel to the installation surface SF1 on which the robot 2 is installed and is a direction from the location where the workpiece W is disposed toward the robot 2, the robot 2 is positioned between the holding mechanism 4a and the holding mechanism 4b. Therefore, in the present embodiment, it is possible to suppress an increase in the movement amount of the robot 2 when attaching the head unit 3 to the robot 2 depending on the head unit 3 attached to the robot 2.

[0114] [2. Modification Example] Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range that does not conflict with each other. Note that for elements whose actions and functions are equivalent to those of the embodiment in the modification examples exemplified below, the reference numerals referred to in the above description are reused, and the detailed description of each is appropriately omitted.

[0115] [First Modification Example] In the above-described embodiment, the case where the heating unit 250 and the irradiation unit 260 are provided in the robot 2 has been illustrated. However, the present invention is not limited to such an aspect. For example, as shown in FIG. 5, an irradiation unit 390 and a heating unit 392 may be provided in each of the head units 3Aa and 3Ab. In this case, the heating unit 250 and the irradiation unit 260 may be omitted from the robot 2. Hereinafter, the head units 3Aa and 3Ab may be collectively referred to as the head unit 3A.

[0116] FIG. 5 is an explanatory diagram for explaining the head unit 3A according to the first modification. In FIG. 5, similar to FIG. 3, the structure of the head unit 3A when viewed from the b2 direction is schematically shown. For example, the "mounted state" in FIG. 5 indicates the state in which the head unit 3A is mounted on the robot 2, and the "non-mounted state" in FIG. 5 indicates the state in which the head unit 3A is removed from the robot 2. Elements similar to those described in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted. The head unit 3Aa corresponds to the head unit 3a, and the head unit 3Ab corresponds to the head unit 3b. The head unit 3Aa is another example of the "first head unit", and the head unit 3Ab is another example of the "second head unit".

[0117] The head unit 3A is the same as the head unit 3 of the above-described embodiment, that is, the head unit 3 shown in FIG. 3 and the like, except that it has an irradiation unit 390, a heating unit 392, and a heat insulating material 394. Further, the robot 2 according to this modified example is the same as the robot 2 of the above-described embodiment, except that the heat insulating material 252, the heating unit 250, and the irradiation unit 260 shown in FIG. 3 are omitted from the robot 2 of the above-described embodiment, and it has a fixing member 230A instead of the fixing member 230 shown in FIG. 3. The heating unit 392 is the same as the heating unit 250 of the above-described embodiment, the heat insulating material 394 is the same as the heat insulating material 252 of the above-described embodiment, and the irradiation unit 390 is the same as the irradiation unit 260 of the above-described embodiment. The heating unit 392 included in the head unit 3Aa is an example of the "third heating unit", and the heating unit 392 included in the head unit 3Ab is an example of the "fourth heating unit".

[0118] The fixing member 230A is located between the arm 226 of the robot 2 and the tool changer 240 of the robot 2, and is connected to the arm 226 and the tool changer 240. Note that the tool changer 240 may be connected to the arm 226 without passing through the fixing member 230A.

[0119] The heat insulating material 394 is located between the tool changer 370 of the head unit 3A and the fourth support portion 334 of the support 330 of the head unit 3A, and is connected to the tool changer 370 and the fourth support portion 334.

[0120] The irradiation unit 390 and the heating unit 392 are attached to the surface SF6 of the second support portion 332 of the support 330. For example, the irradiation unit 390 is attached to the surface SF6 near the end closer to the liquid ejection head 30 among the ends in the direction along the c-axis of the second support portion 332. Further, the heating unit 392 is attached to the surface SF6 of the second support portion 332 at a position in the c1 direction with respect to the irradiation unit 390.

[0121] Thus, also in this modified example, the irradiation unit 390 is positioned behind the liquid ejection head 30 in the moving direction of the liquid ejection head 30. Therefore, also in this modified example, the irradiation unit 390 can irradiate energy to the ink that has just landed on the workpiece W from the liquid ejection head 30. Further, in this modified example, since the irradiation unit 390 can be arranged close to the liquid ejection head 30, the time from when the ink is ejected until it cures can be shortened. As a result, in this modified example, deterioration of the image quality due to bleeding, spreading, etc. of the ink can be reduced.

[0122] Further, in this modified example, as described above, since the heat insulating material 394 is arranged between the tool changer 370 and the fourth support portion 334, transmission of heat from the heater included in the heating unit 392 to the tool changer 370 can be suppressed. Further, in this modified example, since the heating unit 392 can be arranged close to the liquid ejection head 30, in each head unit 3A, the ink can be appropriately heated. Further, for example, in a configuration in which a common heating unit 250 is used for a plurality of head units 3, the thermal conductivity at the connection portion between the tool changer 370 of the head unit 3 and the tool changer 240 of the robot 2 may vary among the plurality of head units 3. In this modified example, there is no connection portion between the tool changer 370 of the head unit 3A and the tool changer 240 of the robot 2 in the path until the heat from the heater included in the heating unit 392 is transmitted to the liquid ejection head 30 and the ink tank 38. Therefore, in this modified example, it is possible to suppress an increase in the individual difference of the head unit 3A with respect to the heating of the ink, and the ink can be appropriately heated in each head unit 3A.

[0123] Note that power may be supplied from the battery 34 to the irradiation unit 390 and the heating unit 392, or power may be supplied to the irradiation unit 390 and the heating unit 392 via the robot 2.

[0124] Furthermore, the configuration of the head unit 3A is not limited to the example shown in FIG. 5. For example, the heating unit 392 may be disposed between the second support portion 332 of the support 330 and the liquid ejection head 30 and attached to the surface SF7 of the second support portion 332. In this case, the head unit 3A may be formed such that in the direction along the c-axis, the third support portion 333 of the support 330 is at the same position as the first support portion 331.

[0125] Also, one or both of the head units 3Aa and 3Ab may not have the irradiation unit 390. For example, when the ink used for the head unit 3Ab is clear ink, since irradiation of energy on the clear ink is unnecessary, the head unit 3Ab may not have the irradiation unit 390. That is, among the plurality of head units 3A, the irradiation unit 390 may be provided in a specific head unit 3A that requires ink curing.

[0126] Also, the robot 2 may have the irradiation unit 260 even when the head unit 3A is employed. In this case, even when the curing of the ink by the irradiation unit 390 is insufficient, the ink can be surely cured by the irradiation unit 260.

[0127] As described above, also in this modification example, the same effects as those of the above-described embodiment can be obtained. Also, in this modification example, the head unit 3Aa has the irradiation unit 390 that irradiates energy for curing the first liquid. Therefore, in this modification example, the irradiation unit 390 can be disposed near the liquid ejection head 30. As a result, in this modification example, the time from when the ink is ejected until it cures can be shortened, and deterioration of the image quality due to bleeding, spreading, etc. of the ink can be reduced.

[0128] In addition, in this modified example, the head unit 3Aa has a heating unit 392 for heating the first liquid, and the head unit 3Ab has a heating unit 392 for heating the second liquid. Therefore, in this modified example, in each head unit 3A, the heating unit 392 can be disposed near the liquid ejection head 30. For this reason, in this modified example, in each head unit 3A, the ink can be appropriately heated.

[0129] In addition, in this modified example, the heating unit 392 included in the head unit 3Ab may heat the second liquid in a state where the head unit 3Ab is not mounted on the robot 2. Similarly, the heating unit 392 included in the head unit 3Aa may heat the first liquid in a state where the head unit 3Aa is not mounted on the robot 2. In this mode, during a period when the head unit 3A is not used for printing, the ink in the liquid ejection head 30 and the ink in the ink tank 38 included in the head unit 3A not used for printing can be heated. Thereby, in this mode, when the head unit 3A is used for printing, the time from when the head unit 3A is mounted on the robot 2 until the ink is heated can be shortened, and the time from when the three-dimensional object printing apparatus 1 starts printing until it ends can be shortened. The period when the head unit 3A is not used for printing is, for example, a printing standby period, an initial setting period, and a startup period of the robot 2. In this mode, the heating unit 392 is an example of the "second heating unit".

[0130] [Second Modified Example] In the above-described embodiment, the heating unit 250 and the irradiation unit 260 are provided on the robot 2, and in the above-described first modified example, the case where the heating unit 392 and the irradiation unit 390 are provided on the head unit 3A has been exemplified. However, the present invention is not limited to such a mode. For example, the heating unit 250 may be provided on the robot 2, and the irradiation unit 390 may be provided on the head unit 3A. Alternatively, the irradiation unit 260 may be provided on the robot 2, and the heating unit 392 may be provided on the head unit 3A. Also in this modified example, the same effects as those of the above-described embodiment and modified example can be obtained.

[0131] Furthermore, in the above-described embodiments, one or both of the heating unit 250 and the irradiation unit 260 may be omitted. Also, in the first modification described above, one or both of the heating unit 392 and the irradiation unit 390 may be omitted. Even in this case, the head unit 3 or 3A can be downsized.

[0132] Also, in the above-described embodiments, the irradiation unit 260 may be provided separately from the robot 2 and the head unit 3. Even in this case, the same effects as those of the above-described embodiments can be obtained.

[0133] [Third Modification Example] In the above-described embodiments and modification examples, the three-dimensional object printing apparatus 1 may further include liquid supply mechanisms 48a and 48b that supply ink to the ink tank 38 of the head unit 3a and the ink tank 38 of the head unit 3b, respectively, as shown in FIG. 6. Similarly, the three-dimensional object printing apparatus 1 may further include liquid supply mechanisms 48a and 48b that supply ink to the ink tank 38 of the head unit 3Aa and the ink tank 38 of the head unit 3Ab, respectively. Hereinafter, the liquid supply mechanisms 48a and 48b may be collectively referred to as the liquid supply mechanism 48.

[0134] FIG. 6 is an explanatory diagram for explaining the three-dimensional object printing apparatus 1 according to the third modification example. Note that the same elements as those described in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In FIG. 6, the three-dimensional object printing apparatus 1 will be described by taking the case where the head unit 3 is adopted as an example. However, in this modification example as well, the head unit 3A shown in FIG. 5 may be adopted. The three-dimensional object printing apparatus 1 shown in FIG. 6 is the same as the three-dimensional object printing apparatus 1 shown in FIG. 1 except that it has a power supply mechanism 44, a liquid supply mechanism 48, and a frame FM10.

[0135] The frame FM10 includes a rectangular frame FM11 and FM12, and a plurality of frames FM13 that support the frame FM12 at an interval in the Z1 direction with respect to the frame FM11. The frame FM11 surrounds the holding mechanisms 4a, 4b, and the pedestal ST, and is connected to the holding mechanisms 4a, 4b, and the pedestal ST. Further, liquid supply mechanisms 48a and 48b are attached to the frame FM12. The elements including the liquid supply mechanism 48a and the liquid supply mechanism 48b are an example of a "liquid supply mechanism".

[0136] The liquid supply mechanism 48 has a pipe 482 connected to the supply port 382 of the ink tank 38 when supplying ink to the ink tank 38. The pipe 482 is provided to be expandable and contractible in the direction along the Z axis, for example.

[0137] For example, when the liquid supply mechanism 48a supplies ink to the ink tank 38 of the head unit 3a held by the holding mechanism 4a under the control of the controller 5, the pipe 482 is connected to the supply port 382 of the ink tank 38 of the head unit 3a. Then, ink is supplied from an ink bottle (not shown) storing the ink used by the head unit 3a to the ink tank 38 via the liquid supply mechanism 48a. Also, when the liquid supply mechanism 48b supplies ink to the ink tank 38 of the head unit 3b held by the holding mechanism 4b under the control of the controller 5, the pipe 482 is connected to the supply port 382 of the ink tank 38 of the head unit 3b. Then, ink is supplied from an ink bottle (not shown) storing the ink used by the head unit 3b to the ink tank 38 via the liquid supply mechanism 48b. For example, the capacity of ink that the ink bottle can store is larger than the capacity of ink that the ink tank 38 can store.

[0138] As described above, in this modification, during the period when the head unit 3 is held by the holding mechanism 4, that is, during the period when the head unit 3 is not being used for printing, ink can be supplied to the ink tank 38 of the head unit 3 that is not being used for printing. As a result, in this modification, the standby time for supplying ink to the ink tank 38 can be shortened, and it is possible to suppress an increase in the time from when the three-dimensional object printing apparatus 1 starts printing until it ends. Note that the connection of the pipe 482 to the supply port 382 of the ink tank 38 may be performed manually. Also, the mounting position of the liquid supply mechanism 48 is not limited to the example shown in FIG. 6. For example, the liquid supply mechanism 48 may be mounted on the frame FM13.

[0139] The power supply mechanism 44 is, for example, a charging device that charges the battery 34. The connection between the power supply mechanism 44 and the battery 34 when the power supply mechanism 44 charges the battery 34 may be wireless or wired.

[0140] In the example shown in FIG. 6, the power supply mechanism 44a is disposed in the third portion 413 of the main body member 410 of the holding mechanism 4a, and the power supply mechanism 44b is disposed in the third portion 413 of the main body member 410 of the holding mechanism 4b. Then, for example, the power supply mechanism 44a supplies power to the battery 34 of the head unit 3a during the period when the head unit 3a is held by the holding mechanism 4a, that is, during the period when the head unit 3a is not attached to the robot 2. Also, for example, the power supply mechanism 44b supplies power to the battery 34 of the head unit 3b during the period when the head unit 3b is held by the holding mechanism 4b, that is, during the period when the head unit 3b is not attached to the robot 2.

[0141] Thus, in this modified example, during the period when the head unit 3 is held by the holding mechanism 4, that is, during the period when the head unit 3 is not used for printing, power can be supplied to the battery 34 of the head unit 3 that is not used for printing. As a result, in this modified example, the standby time for supplying power to the battery 34 can be shortened, and it is possible to suppress an increase in the time from when the three-dimensional object printing apparatus 1 starts printing to when it ends. Note that the connection between the power supply mechanism 44 and the battery 34 may be performed manually or may be automatically executed under the control of the controller 5. Further, the mounting position of the power supply mechanism 44 is not limited to the example shown in FIG. 6. For example, the power supply mechanism 44 may be attached to the frame FM13.

[0142] As described above, also in this modified example, effects similar to those of the above-described embodiments and modified examples can be obtained. Further, in this modified example, the three-dimensional object printing apparatus 1 further includes a liquid supply mechanism 48 that supplies the first liquid and the second liquid to the ink tank 38 of the head unit 3a and the ink tank 38 of the head unit 3b, respectively. The liquid supply mechanism 48 supplies the first liquid to the ink tank 38 of the head unit 3a in a state where the head unit 3a is not attached to the robot 2, and supplies the second liquid to the ink tank 38 of the head unit 3b in a state where the head unit 3b is not attached to the robot 2. Thus, in this modified example, since the liquid can be supplied to the ink tank 38 of the head unit 3 that is not used for printing, the standby time for supplying the liquid to the ink tank 38 can be shortened. As a result, in this modified example, it is possible to suppress an increase in the time from when the three-dimensional object printing apparatus 1 starts printing to when it ends.

[0143] As described above, in this modified example, the three-dimensional object printing apparatus 1 further includes a power supply mechanism 44 that supplies power to the battery 34 of the head unit 3a and the battery 34 of the head unit 3b. The power supply mechanism 44 supplies power to the battery 34 of the head unit 3a when the head unit 3a is not attached to the robot 2, and supplies power to the battery 34 of the head unit 3b when the head unit 3b is not attached to the robot 2. Thus, in this modified example, since power can be supplied to the battery 34 of the head unit 3 that is not being used for printing, the standby time for supplying power to the battery 34 can be shortened. As a result, in this modified example, it is possible to suppress an increase in the time from when the three-dimensional object printing apparatus 1 starts printing until it ends.

[0144] Note that either the power supply mechanism 44 or the liquid supply mechanism 48 may be omitted from the three-dimensional object printing apparatus 1 shown in FIG. 6. Even in this case, an effect similar to that of the above-described modified example can be obtained, except for the effect obtained by the omitted element.

[0145] [Fourth Modified Example] In the above-described embodiments and modified examples, the case where the maintenance unit 46 is provided for each holding mechanism 4 has been illustrated, but the present invention is not limited to such an aspect. For example, the three-dimensional object printing apparatus 1 may have a maintenance unit 46 that is commonly used by a plurality of head units 3. Specifically, the three-dimensional object printing apparatus 1 may have a maintenance mechanism having the same configuration as the holding mechanism 4 shown in FIG. 4 as a maintenance unit 46 that is commonly used by a plurality of head units 3. In this case, the maintenance unit 46 may be omitted from each holding mechanism 4.

[0146] For example, the above-described maintenance mechanism may maintain the liquid discharge head 30 of the head unit 3a with the head unit 3a mounted on the robot 2, and may maintain the liquid discharge head 30 of the head unit 3b with the head unit 3b mounted on the robot 2. In this aspect, since the liquid discharge head 30 of the head unit 3 can be maintained with the head unit 3 mounted on the robot 2, the time required for maintenance can be shortened by the time for attaching and detaching the head unit 3 from the robot 2. As a result, in this aspect, the time required for maintaining the liquid discharge head 30 of the head unit 3 mounted on the robot 2 can be shortened.

[0147] Note that also in this modification, the above-described maintenance mechanism may maintain the liquid discharge head 30 of the head unit 3 only when the head unit 3 is removed from the robot 2. In this aspect, since the liquid discharge head 30 of the head unit 3 not mounted on the robot 2 can be maintained, the maintenance of the liquid discharge head 30 can be efficiently performed.

[0148] Further, in this modification, when each holding mechanism 4 has a maintenance unit 46, it is possible to shorten the time required for maintaining the liquid discharge head 30 of the head unit 3 mounted on the robot 2 while efficiently performing the maintenance of the liquid discharge head 30.

[0149] [Fifth Modification Example] In the above-described embodiments and modification examples, the case where the holding mechanism 4a is disposed at a position in the Y1 direction and the holding mechanism 4b is disposed at a position in the Y2 direction with respect to the pedestal ST on which the base 210 of the robot 2 is installed is illustrated. However, the present invention is not limited to such an aspect. For example, both the holding mechanisms 4a and 4b may be disposed at positions in the Y1 direction with respect to the pedestal ST, or both the holding mechanisms 4a and 4b may be disposed at positions in the Y2 direction with respect to the pedestal ST.

[0150] FIG. 7 is an explanatory diagram for explaining the three-dimensional object printing apparatus 1 according to the fifth modification. FIG. 7 schematically shows the three-dimensional object printing apparatus 1 when viewed from the Z1 direction. Note that elements similar to those described in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In FIG. 7, the three-dimensional object printing apparatus 1 will be described by taking the case where the head unit 3 is adopted as an example. However, in this modification, the head unit 3A shown in FIG. 5 may also be adopted. The three-dimensional object printing apparatus 1 shown in FIG. 7 is the same as the three-dimensional object printing apparatus 1 shown in FIG. 1, except that both the holding mechanisms 4a and 4b are arranged at positions in the Y1 direction from the pedestal ST.

[0151] As shown in FIG. 7, when viewed from the robot 2, the holding mechanisms 4a and 4b are located in the same direction with respect to the robot 2 in a direction parallel to the installation surface SF1 on which the robot 2 is installed and in the X1 direction that is the direction from the location where the work W is arranged toward the robot 2, that is, in a direction parallel to the installation surface SF1 and perpendicular to the X1 direction, that is, in the direction along the Y axis. Thus, in this modification, since the holding mechanism 4b is arranged near the holding mechanism 4a, the amount of movement of the robot 2 when replacing the head unit 3 attached to the robot 2 can be reduced.

[0152] Further, in this modification, it is assumed that the ink used in the head unit 3a is black ink and the ink used in the head unit 3b is ink other than black ink. As shown in FIG. 7, the distance DISa between the holding mechanism 4a and the work W is shorter than the distance DISa between the holding mechanism 4b and the work W. In general printing, the frequency of use of black ink is higher than the frequency of use of other color inks. Thus, in this modification, since the holding mechanism 4a that holds the head unit 3a having the liquid discharge head 30 that discharges the frequently used ink is arranged near the work W, the throughput of printing can be improved.

[0153] [Sixth Modification] In the above-described embodiments and modifications, the case where the three-dimensional object printing apparatus 1 has two head units 3 has been exemplified, but the present invention is not limited to such an aspect. For example, the three-dimensional object printing apparatus 1 may have three or more head units 3.

[0154] FIG. 8 is an explanatory diagram for explaining the three-dimensional object printing apparatus 1 according to the sixth modification. FIG. 8 schematically shows the three-dimensional object printing apparatus 1 when viewed from the Z1 direction. Note that the same elements as those described in FIGS. 1 to 7 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In FIG. 8, the three-dimensional object printing apparatus 1 will be described by taking the case where the head unit 3 is employed as an example, but in this modification as well, the head unit 3A shown in FIG. 5 may be employed. The three-dimensional object printing apparatus 1 shown in FIG. 8 is the same as the three-dimensional object printing apparatus 1 shown in FIG. 7 except that it has a head unit 3c and a holding mechanism 4c. The head unit 3c is an example of a "third head unit", and the holding mechanism 4c is an example of a "third holding mechanism".

[0155] The head unit 3c is the same as the head unit 3a. However, the color of the ink used in the head unit 3c is different from the color of the ink used in the head unit 3a. For example, the ink used in the head unit 3a is black ink, and the ink used in the head unit 3c is magenta ink. Note that the ink used in the head unit 3b is yellow ink.

[0156] The holding mechanism 4c is the same as the holding mechanism 4a. In this modification, all of the holding mechanisms 4a, 4b, and 4c are arranged at positions in the Y1 direction relative to the pedestal ST. For example, the distance DISc between the holding mechanism 4c and the work W is shorter than the distance DISb between the holding mechanism 4b and the work W, and longer than the distance DISa between the holding mechanism 4a and the work W. In general printing, the frequency of use of black ink is higher than that of other color inks, and the frequency of use of magenta ink tends to be higher than that of yellow ink. In this modification, since the holding mechanism 4 that holds the head unit 3 having the liquid ejection head 30 that ejects the frequently used ink is arranged near the work W, the printing throughput can be improved.

[0157] Thus, in this modification, the holding mechanism 4 is arranged such that the distance between the holding mechanism 4 that holds the head unit 3 using the frequently used ink and the work W is shorter than the distance between the holding mechanism 4 that holds the head unit 3 using the less frequently used ink and the work W.

[0158] Note that the combination of inks used in the head units 3a, 3b, and 3c is not limited to the above example. For example, the color of the ink used in the head unit 3a may be the same as the color of the ink used in the head unit 3b. In this case, for example, when the ink in the head unit 3a mounted on the robot 2 runs out, by replacing it with the head unit 3b that uses the same color ink as the ink used in the head unit 3a, printing can be restarted without waiting until the ink tank 38 of the head unit 3a is supplied with ink.

[0159] Further, for example, when the three-dimensional object printing apparatus 1 has four head units 3, black ink, cyan ink, magenta ink, and yellow ink may be used by the four head units 3 respectively. Since black ink and yellow ink are used together less frequently in color separation, the holding mechanism 4 that holds the head unit 3 using black ink and the holding mechanism 4 that holds the head unit 3 using yellow ink may be arranged separately. For example, among the four holding mechanisms 4 corresponding to the four head units 3, the holding mechanism 4 that holds the head unit 3 using black ink is arranged at the position closest to the work W. And, among the four holding mechanisms 4, the holding mechanism 4 that holds the head unit 3 using yellow ink may be arranged at the position farthest from the work W. Also, another holding mechanism 4 may be arranged between the holding mechanism 4 that holds the head unit 3 using black ink and the holding mechanism 4 that holds the head unit 3 using yellow ink.

[0160] Further, when there are many cases of executing monochrome printing, the four holding mechanisms 4 corresponding to the four head units 3 may be arranged as follows. The holding mechanism 4 that holds the head unit 3 using black ink may be arranged at the position closest to the work W, and the holding mechanism 4 that holds the head unit 3 using cyan ink may be arranged at the position farthest from the work W. And, the holding mechanism 4 that holds the head unit 3 using yellow ink may be arranged at the position second closest to the work W, and the holding mechanism 4 that holds the head unit 3 using magenta ink may be arranged at the position third closest to the work W.

[0161] [Seventh Modification Example] In the above-described embodiments and modification examples, each holding mechanism 4 may have a light-shielding portion 49 that blocks light directed toward the liquid ejection head 30 of the head unit 3 being held, as shown in FIG. 9.

[0162] FIG. 9 is an explanatory diagram for explaining a three-dimensional object printing apparatus 1 according to a seventh modification. For elements similar to those described in FIGS. 1 to 8, the same reference numerals are given and detailed descriptions thereof are omitted. In FIG. 9, the three-dimensional object printing apparatus 1 will be described by taking the case where the head unit 3 is adopted as an example. However, also in this modification, the head unit 3A shown in FIG. 5 may be adopted. The three-dimensional object printing apparatus 1 shown in FIG. 9 is the same as the three-dimensional object printing apparatus 1 shown in FIG. 1, except that a light-shielding portion 49 is provided in the holding mechanism 4.

[0163] The holding mechanism 4a has a light-shielding portion 49 that blocks the light directed toward the liquid ejection head 30 of the head unit 3a in a state of holding the head unit 3a. Similarly, the holding mechanism 4b has a light-shielding portion 49 that blocks the light directed toward the liquid ejection head 30 of the head unit 3b in a state of holding the head unit 3b. For example, the light-shielding portion 49 is arranged so as to block the light from the irradiation portion 260 between the irradiation portion 260 and the liquid ejection head 30 of the head unit 3 held by the holding mechanism 4. In the example shown in FIG. 9, plate-like side walls surrounding the first portion 411, the second portion 412, and the third portion 413 of the main body member 410 shown in FIG. 4 are provided as the light-shielding portion 49 in each holding mechanism 4. Note that the shape and arrangement of the light-shielding portion 49 are not particularly limited as long as the light from the irradiation portion 260 can be blocked. The light-shielding portion 49 included in the holding mechanism 4a is an example of a “first light-shielding portion”, and the light-shielding portion 49 included in the holding mechanism 4b is an example of a “second light-shielding portion”.

[0164] As described above, also in this modified example, the same effects as those of the above-described embodiments and modified examples can be obtained. Further, in this modified example, the holding mechanism 4a has a light-shielding portion 49 that blocks light traveling toward the liquid ejection head 30 of the head unit 3a in a state of holding the head unit 3a, and the holding mechanism 4b has a light-shielding portion 49 that blocks light traveling toward the liquid ejection head 30 of the head unit 3b in a state of holding the head unit 3b. Thereby, in this modified example, when light is irradiated from the irradiation unit 260, it is possible to suppress the ink from curing due to the light from the irradiation unit 260 hitting the liquid ejection head 30 of the head unit 3 held by the holding mechanism 4. In addition, the head unit 3 with a low usage frequency may have a long standby time until it is used for printing. In this modified example, since each holding mechanism 4 has a light-shielding portion 49 that blocks light traveling toward the liquid ejection head 30, even when the standby time of the head unit 3 until it is used for printing becomes long, it is possible to suppress clogging of the nozzles N due to light reaching the liquid ejection head 30.

[0165] [Eighth Modified Example] In the above-described embodiments and modified examples, as shown in FIG. 10, the three-dimensional object printing apparatus 1 may have a correction unit 522 that corrects the path along which the robot 2 moves based on the respective mounting errors when the head units 3a and 3b are mounted on the robot 2.

[0166] FIG. 10 is a block diagram showing the electrical configuration of the three-dimensional object printing apparatus 1 according to the eighth modified example. Elements similar to those described in FIGS. 1 to 9 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In FIG. 10, the three-dimensional object printing apparatus 1 will be described by taking the case where the head unit 3 is adopted as an example. However, also in this modified example, the head unit 3A shown in FIG. 5 may be adopted. The three-dimensional object printing apparatus 1 shown in FIG. 10 is the same as the three-dimensional object printing apparatus 1 shown in FIG. 2, except that the processing circuit 50 functions as an arm control unit 52A having an acquisition unit 520 and a correction unit 522 instead of functioning as the arm control unit 52 shown in FIG. 2.

[0167] The configuration of the controller 5 shown in FIG. 10 is the same as that of the controller 5 shown in FIG. 2. However, the memory circuit 58 stores the program PR2 instead of the program PR1 shown in FIG. 2. For this reason, the processing circuit 50 shown in FIG. 10 functions as an arm control unit 52A instead of the arm control unit 52 shown in FIG. 2 by operating according to the program PR2 stored in the memory circuit 58. Note that the processing circuit 50 shown in FIG. 10 also functions as an irradiation control unit 54 and a maintenance control unit 56 in the same manner as the processing circuit 50 shown in FIG. 2 by operating according to the program PR2. The arm control unit 52A is the same as the arm control unit 52 shown in FIG. 2, except that it has an acquisition unit 520 and a correction unit 522.

[0168] The acquisition unit 520 acquires error information indicating respective mounting errors when the head unit 3a and the head unit 3b are mounted on the robot 2. The mounting errors include, for example, the inclination and posture deviation of the head unit 3 mounted on the robot 2, and the mechanical tolerances of the head unit 3 and the robot 2 itself. Also, the mounting error may be detected, for example, at the start of use of the three-dimensional object printing apparatus 1, or at the time of shipment of the three-dimensional object printing apparatus 1. Further, the mounting error may be detected, for example, when the head unit 3 is mounted on the robot 2, or at the time of calibration for associating the tool coordinate system with the base coordinate system or the robot coordinate system. Alternatively, the mounting error may be calculated based on the result of preliminary printing performed before this printing. Also, the detection or calculation of the mounting error may be executed by a functional block realized by the processing circuit 50, or may be executed by an element external to the processing circuit 50. Alternatively, the three-dimensional object printing apparatus 1 may have a detection device such as an imaging device and a distance sensor for executing the detection or calculation of the mounting error. Note that the acquisition of the error information by the acquisition unit 520 is not limited to acquiring the error information from a detection device or the like external to the processing circuit 50. For example, the acquisition of the error information by the acquisition unit 520 includes acquiring the error information from an element other than the processing circuit 50 in the controller 5, and acquiring the error information from another functional block realized by the processing circuit 50.

[0169] The correction unit 522 corrects the path along which the robot 2 moves based on the mounting error indicated by the error information acquired by the acquisition unit 520. For example, the correction unit 522 may correct the path indicated by the path information Dp stored in the memory circuit 58 based on the mounting error indicated by the error information acquired by the acquisition unit 520. Alternatively, the correction unit 522 may correct parameters such as a transformation matrix or an inverse transformation matrix that associates the tool coordinate system with the base coordinate system or the robot coordinate system based on the mounting error indicated by the error information acquired by the acquisition unit 520. That is, the correction unit 522 may correct the path along which the robot 2 moves by correcting parameters such as a transformation matrix or an inverse transformation matrix.

[0170] As described above, also in this modification example, the same effects as those of the above-described embodiment and modification examples can be obtained. Further, in this modification example, the three-dimensional object printing apparatus 1 further includes an acquisition unit 520 that acquires error information indicating respective mounting errors when the head unit 3a and the head unit 3b are mounted on the robot 2, and a correction unit 522 that corrects the path along which the robot 2 moves based on the mounting error indicated by the error information. Thereby, in this modification example, since the error can be corrected for each head unit 3, the print quality can be improved.

[0171] [Modification Example 9] In the above-described embodiments and modified examples, the case where the head unit 3 or 3A has the control module 36 has been exemplified. However, the present invention is not limited to such a mode. For example, some or all of the timing signal generation circuit 360, the control circuit 362, and the drive signal generation circuit 364 included in the control module 36 may be provided outside the head unit 3 or 3A. Specifically, for example, the robot 2 may have the timing signal generation circuit 360, the control circuit 362, and the drive signal generation circuit 364. Alternatively, for example, the head unit 3 or 3A may have the drive signal generation circuit 364, and the robot 2 may have the timing signal generation circuit 360 and the control circuit 362. In this case, the elements including the drive signal generation circuit 364 and the switch circuit 32 included in the head unit 3a or 3Aa correspond to the "first drive circuit", and the elements including the drive signal generation circuit 364 and the switch circuit 32 included in the head unit 3b or 3Ab correspond to the "second drive circuit". Also, the control signal SI corresponds to the "print data", and the control circuit 362 corresponds to the "data transmission unit". In this modified example as well, the same effects as those of the above-described embodiments and modified examples can be obtained.

[0172] [10th Modified Example] In the above-described embodiments and modified examples, the case where the head unit 3 or 3A has the battery 34 has been exemplified. However, the present invention is not limited to such a mode. For example, the head unit 3 or 3A may not have the battery 34. In this case, circuits such as the switch circuit 32 provided in the head unit 3 or 3A may be supplied with power via the robot 2. In this modified example as well, the same effects as those of the above-described embodiments and modified examples can be obtained.

[0173] [11th Modified Example] In the above-described embodiments and modified examples, the case where one head unit 3 is held by one holding mechanism 4 has been exemplified. However, the present invention is not limited to such a mode. For example, one holding mechanism 4 may hold a plurality of head units 3. That is, the three-dimensional object printing apparatus 1 may have a holding mechanism 4 that holds a plurality of head units 3. Also in this modified example, the same effects as those of the above-described embodiments and modified examples can be obtained.

[0174] [12th Modified Example] In the above-described embodiments and modified examples, the case where the three-dimensional object printing apparatus 1 has the maintenance unit 46 has been exemplified. However, the present invention is not limited to such a mode. For example, the three-dimensional object printing apparatus 1 may not have the maintenance unit 46. Also in this modified example, the same effects as those of the above-described embodiments and modified examples can be obtained except for the effects obtained by the maintenance unit 46.

[0175] [3. Supplementary Note] From the forms exemplified above, for example, the following configurations can be understood.

[0176] The three-dimensional object printing apparatus according to Aspect 1 which is a preferred aspect includes a first head unit having a first liquid discharge head that discharges a first liquid, a second head unit having a second liquid discharge head that discharges a second liquid, and a moving mechanism that moves the first head unit with respect to a three-dimensional workpiece in a state where the first head unit is mounted, and moves the second head unit with respect to the workpiece in a state where the second head unit is mounted. The first head unit and the second head unit are detachable from the moving mechanism. According to Aspect 1, since the first liquid discharge head and the second liquid discharge head can be miniaturized, the first head unit and the second head unit can be miniaturized.

[0177] In the three-dimensional object printing apparatus according to Embodiment 2, which is a specific example of Embodiment 1, the first head unit has a first ink tank in which the first liquid is stored, and the second head unit has a second ink tank in which the second liquid is stored. According to Embodiment 2, since the first head unit and the second head unit each have a first ink tank and a second ink tank, the configuration of the three-dimensional object printing apparatus can be simplified.

[0178] In the three-dimensional object printing apparatus according to Embodiment 3, which is a specific example of Embodiment 2, the apparatus further includes a liquid supply mechanism that supplies the first liquid and the second liquid to the first ink tank and the second ink tank, respectively. The liquid supply mechanism supplies the first liquid to the first ink tank in a state where the first head unit is not attached to the moving mechanism, and supplies the second liquid to the second ink tank in a state where the second head unit is not attached to the moving mechanism. According to Embodiment 3, since the liquid can be supplied to the first ink tank of the first head unit that is not being used for printing, the waiting time for supplying the first liquid to the first ink tank can be shortened. Similarly, the waiting time for supplying the second liquid to the second ink tank can be shortened.

[0179] In the three-dimensional object printing apparatus according to Embodiment 4, which is a specific example of Embodiment 2 or 3, the first head unit has a first pressure adjustment unit that adjusts the pressure applied to the first liquid supplied from the first ink tank to the first liquid discharge head, and the second head unit has a second pressure adjustment unit that adjusts the pressure applied to the second liquid supplied from the second ink tank to the second liquid discharge head. According to Embodiment 4, even when the posture of the first head unit attached to the moving mechanism changes, the pressure applied to the first liquid can be adjusted in the first head unit attached to the moving mechanism, so that the first liquid can be appropriately discharged from the first liquid discharge head to the workpiece. Similarly, the second liquid can be appropriately discharged from the second liquid discharge head to the workpiece.

[0180] In the three-dimensional object printing apparatus according to Embodiment 5, which is a specific example of any one of Embodiments 1 to 4, the moving mechanism is provided separately from the first head unit and the second head unit, and has an irradiation unit that irradiates energy for curing the first liquid and the second liquid. According to Embodiment 5, since the irradiation unit is provided in the moving mechanism, it is possible to suppress the complication of the configuration around the irradiation unit.

[0181] In the three-dimensional object printing apparatus according to Embodiment 6, which is a specific example of any one of Embodiments 1 to 5, the first head unit has an irradiation unit that irradiates energy for curing the first liquid. According to Embodiment 6, since the irradiation unit can be arranged near the first liquid discharge head, the time from when the first liquid is discharged until it is cured can be shortened.

[0182] In the three-dimensional object printing apparatus according to Embodiment 7, which is a specific example of any one of Embodiments 1 to 6, the moving mechanism is provided separately from the first head unit and the second head unit, and has a first heating unit that heats the liquid, and the first heating unit heats the first liquid with the first head unit mounted. According to Embodiment 7, since the first heating unit is provided in the moving mechanism, it is possible to suppress the complication of the configuration around the first heating unit.

[0183] The three-dimensional object printing apparatus according to Embodiment 8, which is a specific example of any one of Embodiments 1 to 7, further includes a second heating unit that heats the liquid, and the second heating unit heats the second liquid in a state where the second head unit is not mounted on the moving mechanism. According to Embodiment 8, since the second liquid can be heated in a state where the second head unit is not mounted on the moving mechanism, the time from when the second head unit is mounted on the moving mechanism until the second liquid droplet is heated can be shortened.

[0184] In the three-dimensional object printing apparatus according to Aspect 9, which is a specific example of any one of Aspects 1 to 8, the first head unit has a third heating unit that heats the first liquid, and the second head unit has a fourth heating unit that heats the second liquid. According to Aspect 9, since the third heating unit can be arranged near the first liquid ejection head, the first liquid can be appropriately heated. Similarly, the second liquid can be appropriately heated.

[0185] In the three-dimensional object printing apparatus according to Aspect 10, which is a specific example of any one of Aspects 1 to 9, the first head unit has a first drive circuit that generates a first drive signal for driving the first liquid ejection head, and a first battery that stores electric power supplied to the first drive circuit, and the second head unit has a second drive circuit that generates a second drive signal for driving the second liquid ejection head, and a second battery that stores electric power supplied to the second drive circuit. According to Aspect 10, since the first head unit has the first drive circuit and the first battery, it is not necessary to configure the wiring for supplying electric power to the first drive circuit to be detachable. Similarly, it is not necessary to configure the wiring for supplying electric power to the second drive circuit to be detachable. As a result, the configuration of the three-dimensional object printing apparatus can be simplified.

[0186] The three-dimensional object printing apparatus according to Aspect 11, which is a specific example of the aspect of Aspect 10, further includes a power supply mechanism that supplies electric power to the first battery and the second battery, and the power supply mechanism supplies electric power to the first battery in a state where the first head unit is not mounted on the moving mechanism, and supplies electric power to the second battery in a state where the second head unit is not mounted on the moving mechanism. According to Aspect 11, since power can be supplied to the first battery of the first head unit that is not being used for printing, the standby time for supplying power to the first battery can be shortened. Similarly, the standby time for supplying power to the second battery can be shortened. As a result, it is possible to suppress an increase in the time from when the three-dimensional object printing apparatus starts printing to when it ends.

[0187] The liquid ejection head according to Aspect 12, which is a specific example of Aspect 10 or 11, further includes a data transmission unit that transmits print data to the first drive circuit and the second drive circuit. The data transmission unit transmits the print data to the second drive circuit in a state where the second head unit is not attached to the moving mechanism. When the second head unit is attached to the moving mechanism, the second drive circuit supplies the second drive signal to the second liquid ejection head based on the print data. According to Aspect 12, since print data is also transmitted to the second drive circuit of the second head unit that is not attached to the moving mechanism, the throughput from when the second head unit is attached to the moving mechanism until the second drive signal is supplied to the second liquid ejection head can be improved.

[0188] The three-dimensional object printing apparatus according to Aspect 13, which is a specific example of any one of Aspects 1 to 12, further includes a maintenance mechanism for maintaining the first liquid ejection head and the second liquid ejection head. The maintenance mechanism maintains the first liquid ejection head in a state where the first head unit is not attached to the moving mechanism, and maintains the second liquid ejection head in a state where the second head unit is not attached to the moving mechanism. According to Aspect 13, since the first liquid ejection head of the first head unit that is not attached to the moving mechanism can be maintained, the maintenance of the first liquid ejection head can be efficiently performed. Similarly, the maintenance of the second liquid ejection head can be efficiently performed.

[0189] The three-dimensional object printing apparatus according to Embodiment 14, which is a specific example of any one of Embodiments 1 to 13, includes a maintenance mechanism that maintains the first liquid ejection head in a state where the first head unit is attached to the movement mechanism and maintains the second liquid ejection head in a state where the second head unit is attached to the movement mechanism. According to Embodiment 14, since the first liquid ejection head of the first head unit can be maintained in a state where the first head unit is attached to the movement mechanism, the time required for maintenance can be shortened by the time required to attach and detach the first head unit from the movement mechanism.

[0190] The three-dimensional object printing apparatus according to Embodiment 15, which is a specific example of any one of Embodiments 1 to 14, includes a first holding mechanism that holds the first head unit and a second holding mechanism that holds the second head unit. When the movement mechanism is viewed in a first direction that is parallel to the installation surface on which the movement mechanism is installed and in a direction from the location where the workpiece is placed toward the movement mechanism, the movement mechanism is located between the first holding mechanism and the second holding mechanism. According to Embodiment 15, since the movement mechanism is located between the first holding mechanism and the second holding mechanism, it is possible to suppress an increase in the movement amount of the movement mechanism when attaching the first head unit or the second head unit to the movement mechanism depending on the head unit to be attached to the movement mechanism.

[0191] The three-dimensional object printing apparatus according to Embodiment 16, which is a specific example of any one of Embodiments 1 to 14, includes a first holding mechanism that holds the first head unit and a second holding mechanism that holds the second head unit. When the movement mechanism is viewed in a first direction that is parallel to the installation surface on which the movement mechanism is installed and in a direction from the location where the workpiece is placed toward the movement mechanism, in a direction parallel to the installation surface and perpendicular to the first direction, the first holding mechanism and the second holding mechanism are located in the same direction with respect to the movement mechanism. According to Aspect 16, since the second holding mechanism is arranged near the first holding mechanism, the moving amount of the moving mechanism when replacing the head unit attached to the moving mechanism from the first head unit to the second head unit can be reduced. Similarly, the moving amount of the moving mechanism when replacing the head unit attached to the moving mechanism from the second head unit to the first head unit can be reduced.

[0192] A three-dimensional object printing apparatus according to Aspect 17, which is a specific example of any one of Aspects 1 to 16, includes a first holding mechanism that holds the first head unit, and a second holding mechanism that holds the second head unit. The first liquid is a black liquid, the second liquid is a liquid other than black, and the distance between the first holding mechanism and the workpiece is shorter than the distance between the second holding mechanism and the workpiece. According to Aspect 17, since the first holding mechanism that holds the first head unit having the first liquid ejection head that ejects the first liquid with a high usage frequency is arranged near the workpiece, the throughput of printing can be improved.

[0193] A three-dimensional object printing apparatus according to Aspect 18, which is a specific example of any one of Aspects 1 to 17, includes a third head unit having a third liquid ejection head that ejects a third liquid different from the first liquid and the second liquid, and a third holding mechanism that holds the third head unit. The second liquid is a yellow liquid, the third liquid is a magenta liquid, the distance between the third holding mechanism and the workpiece is shorter than the distance between the second holding mechanism and the workpiece, and longer than the distance between the first holding mechanism and the workpiece. Also in Aspect 18, since the first holding mechanism that holds the first head unit having the first liquid ejection head that ejects the first liquid with a high usage frequency is arranged near the workpiece, the throughput of printing can be improved.

[0194] A three-dimensional object printing apparatus according to Embodiment 19, which is a specific example of any one of Embodiments 1 to 18, includes a first holding mechanism that holds the first head unit, and a second holding mechanism that holds the second head unit. The first holding mechanism has a first light-shielding portion that blocks light directed toward the first liquid ejection head in a state where the first head unit is held, and the second holding mechanism has a second light-shielding portion that blocks light directed toward the second liquid ejection head in a state where the second head unit is held. According to Embodiment 19, since the first holding mechanism has the first light-shielding portion that blocks light directed toward the first liquid ejection head, even when the standby time of the first head unit until it is used for printing becomes long, it is possible to suppress clogging of the nozzles due to the light reaching the first liquid ejection head.

[0195] A three-dimensional object printing apparatus according to Embodiment 20, which is a specific example of any one of Embodiments 1 to 19, includes an acquisition unit that acquires error information indicating respective mounting errors when the first head unit and the second head unit are mounted on the moving mechanism, and a correction unit that corrects a path along which the moving mechanism moves based on the mounting errors indicated by the error information. According to Embodiment 20, since errors can be corrected in each of the first head unit and the second head unit, the print quality can be improved.

Description of Reference Numerals

[0196] 1...Three-dimensional object printing device, 2...Robot, 3, 3a, 3b, 3c, 3A, 3Aa, 3Ab...Head unit, 4, 4a, 4b, 4c...Holding mechanism, 5...Controller, 7...Computer, 20...Arm drive mechanism, 30...Liquid ejection head, 32...Switch circuit, 34...Battery, 36...Control module, 38...Ink tank, 44...Power supply mechanism, 46...Maintenance unit, 48...Liquid supply mechanism, 49...Light-shielding portion, 50...Processing circuit, 52, 52A...Arm control unit, 54...Irradiation control unit, 56...Maintenance control unit, 58...Memory circuit, 70...Processing circuit, 72...Transmission control unit, 74...Generation unit, 78...Memory circuit, 210...Base, 220...Arm, 221...Arm, 222...Arm, 223...Arm, 224...Arm, 225...Arm, 226...Arm, 250...Heating unit, 252...Heat insulating material, 260...Irradiation unit, 310...Self-sealing valve, 360...Timing signal generation circuit, 362...Control circuit, 364...Drive signal generation circuit, 390...Irradiation unit, 392...Heating unit, 394...Heat insulating material, 520...Acquisition unit, 522...Correction unit, CLK...Clock signal, CNG...Change signal, Com...Drive signal, D1...Signal, D3...Signal, Dp...Path information, FN...Ejection surface, Img...Printing data, J...Joint, J1...Joint, J2...Joint, J3...Joint, J4...Joint, J5...Joint, J6...Joint, LAT...Latch signal, O1...Rotation axis, O2...Rotation axis, O3...Rotation axis, O4...Rotation axis, O5...Rotation axis, O6...Rotation axis, PD...Drive pulse, DISa, DISb, DISc...Distance, PR1, PR2...Program, PTS...Timing signal, Wa...Printing area, SI...Control signal, Sk1...Control signal, W...Work, dCom...Waveform specification signal, N...Nozzle, NL...Nozzle row, SF1...Installation surface, SF2...Surface, SF3...Surface, SF4...Surface, SF5...Surface, SF6...Surface, SF7...Surface.

Claims

1. A first head unit having a first liquid ejection head for ejecting a first liquid; A second head unit having a second liquid ejection head for ejecting a second liquid; A moving mechanism that moves the first head unit relative to a three-dimensional workpiece with the first head unit mounted thereon, and moves the second head unit relative to the workpiece with the second head unit mounted thereon; Comprising: The first head unit and the second head unit are detachable from the moving mechanism; A three-dimensional object printing apparatus characterized by this.

2. The first head unit has a first ink tank in which the first liquid is stored; The second head unit has a second ink tank in which the second liquid is stored; The three-dimensional object printing apparatus according to Claim 1.

3. Further comprising a liquid supply mechanism for supplying the first liquid and the second liquid to the first ink tank and the second ink tank, respectively; The liquid supply mechanism: Supplies the first liquid to the first ink tank with the first head unit not mounted on the moving mechanism, and supplies the second liquid to the second ink tank with the second head unit not mounted on the moving mechanism; The three-dimensional object printing apparatus according to Claim 2.

4. The first head unit has a first pressure adjustment unit that adjusts the pressure applied to the first liquid supplied from the first ink tank to the first liquid ejection head; The second head unit has a second pressure adjustment unit that adjusts the pressure applied to the second liquid supplied from the second ink tank to the second liquid ejection head; The three-dimensional object printing apparatus according to Claim 2.

5. The moving mechanism: Is provided separately from the first head unit and the second head unit, and has an irradiation unit that irradiates energy for curing the first liquid and the second liquid; The three-dimensional object printing apparatus according to Claim 1.

6. The first head unit has an irradiation unit that irradiates energy for curing the first liquid; The three-dimensional object printing apparatus according to Claim 1.

7. The moving mechanism: Is provided separately from the first head unit and the second head unit, and has a first heating unit for heating a liquid; The first heating unit: Heats the first liquid with the first head unit mounted thereon; The three-dimensional object printing apparatus according to Claim 1.

8. Further comprising a second heating unit for heating the liquid, The second heating unit, heats the second liquid in a state where the second head unit is not attached to the moving mechanism, The three-dimensional object printing apparatus according to claim 1.

9. The first head unit has a third heating unit for heating the first liquid, The second head unit has a fourth heating unit for heating the second liquid, The three-dimensional object printing apparatus according to claim 1.

10. The first head unit, has a first drive circuit that generates a first drive signal for driving the first liquid ejection head, and a first battery that stores power supplied to the first drive circuit, and, The second head unit, has a second drive circuit that generates a second drive signal for driving the second liquid ejection head, and a second battery that stores power supplied to the second drive circuit, and, The three-dimensional object printing apparatus according to claim 1.

11. Further comprising a power supply mechanism for supplying power to the first battery and the second battery, The power supply mechanism, supplies power to the first battery in a state where the first head unit is not attached to the moving mechanism, and supplies power to the second battery in a state where the second head unit is not attached to the moving mechanism, The three-dimensional object printing apparatus according to claim 10.

12. Further comprising a data transmission unit that transmits print data to the first drive circuit and the second drive circuit, The data transmission unit, transmits the print data to the second drive circuit in a state where the second head unit is not attached to the moving mechanism, The second drive circuit, when the second head unit is attached to the moving mechanism, supplies the second drive signal to the second liquid ejection head based on the print data, The three-dimensional object printing apparatus according to claim 10.

13. Further comprising a maintenance mechanism for maintaining the first liquid ejection head and the second liquid ejection head, The maintenance mechanism, maintains the first liquid ejection head in a state where the first head unit is not attached to the moving mechanism, and maintains the second liquid ejection head in a state where the second head unit is not attached to the moving mechanism, The three-dimensional object printing apparatus according to claim 1.

14. A maintenance mechanism that maintains the first liquid ejection head in a state where the first head unit is attached to the moving mechanism and maintains the second liquid ejection head in a state where the second head unit is attached to the moving mechanism is further provided. The three-dimensional object printing apparatus according to claim 1.

15. A first holding mechanism that holds the first head unit, A second holding mechanism that holds the second head unit, further comprising: The moving mechanism is When the moving mechanism is viewed in a first direction that is parallel to the installation surface on which the moving mechanism is installed and is a direction from the location where the workpiece is placed toward the moving mechanism, the first holding mechanism is located between the first holding mechanism and the second holding mechanism. The three-dimensional object printing apparatus according to any one of claims 1 to 14.

16. A first holding mechanism that holds the first head unit, A second holding mechanism that holds the second head unit, further comprising: When the moving mechanism is viewed in a first direction that is parallel to the installation surface on which the moving mechanism is installed and is a direction from the location where the workpiece is placed toward the moving mechanism, in a direction parallel to the installation surface and perpendicular to the first direction, the first holding mechanism and the second holding mechanism are located in the same direction with respect to the moving mechanism. The three-dimensional object printing apparatus according to any one of claims 1 to 14.

17. A first holding mechanism that holds the first head unit, A second holding mechanism that holds the second head unit, further comprising: The first liquid is a black liquid, The second liquid is a liquid other than black, The distance between the first holding mechanism and the workpiece is shorter than the distance between the second holding mechanism and the workpiece. The three-dimensional object printing apparatus according to any one of claims 1 to 14.

18. A third head unit having a third liquid ejection head that ejects a third liquid different from the first liquid and the second liquid, A third holding mechanism that holds the third head unit, further comprising: The second liquid is a yellow liquid, The third liquid is a magenta liquid, The distance between the third holding mechanism and the workpiece is shorter than the distance between the second holding mechanism and the workpiece and longer than the distance between the first holding mechanism and the workpiece. The three-dimensional object printing apparatus according to claim 17.

19. A first holding mechanism that holds the first head unit, a second holding mechanism for holding the second head unit; further comprising; the first holding mechanism; has a first light-shielding portion that blocks light directed toward the first liquid ejection head in a state of holding the first head unit; the second holding mechanism; has a second light-shielding portion that blocks light directed toward the second liquid ejection head in a state of holding the second head unit; The three-dimensional object printing apparatus according to any one of claims 1 to 14.

20. an acquisition unit that acquires error information indicating respective mounting errors when the first head unit and the second head unit are mounted on the moving mechanism; a correction unit that corrects a path along which the moving mechanism moves based on the mounting error indicated by the error information; further comprising; The three-dimensional object printing apparatus according to any one of claims 1 to 14.

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