Three-dimensional object printing method and three-dimensional object printing device

Abstract

To appropriately cure or solidify liquid on three-dimensional workpiece.SOLUTION: A three-dimensional object printing method includes a first operation of simultaneously performing discharge of liquid to workpiece by a head, emission of energy to the workpiece by an energy emitting part, and relative moving of the head and the energy emitting part to the workpiece by a moving mechanism, and second operation of simultaneously performing the emission of the energy to the workpiece by the energy emitting part and the relative moving of the head and the energy emitting part to the workpiece by the moving mechanism, subsequent to the first operation in the same printing path as the first operation, and not performing the discharge of the liquid to the workpiece by the head, wherein a first emission distance that is a distance between the workpiece in a normal direction of the emission surface and the emission surface during execution of the first operation, and a second irradiation distance that is a distance between the workpiece in the normal direction of the emission surface and the emission surface during execution of the second operation are different.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a three-dimensional object printing method and a three-dimensional object printing device. [Background technology]

[0002] Three-dimensional printing devices that use an inkjet printing method to print on the surface of a three-dimensional workpiece are known. For example, the device described in Patent Document 1 has a robot arm, a print head fixed to the tip of the robot arm, and an ultraviolet radiation device, and prints an image on the object using ink from the print head. Here, the ultraviolet radiation device radiates ultraviolet light that hardens the ink on the object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-050832 Summary of the Invention [Problem to be solved by the invention]

[0004] Although Patent Document 1 does not specifically describe how ultraviolet light is irradiated onto the ink on the object, it is desirable to properly cure the ink. [Means for solving the problem]

[0005] In order to solve the above problems, one aspect of the three-dimensional object printing method according to the present disclosure is a three-dimensional object printing method using a head having an ejection surface provided with nozzles that eject liquid, an energy emission unit having an emission surface that emits energy that hardens or solidifies the liquid ejected from the head, and a movement mechanism that changes the relative positions of the head and the energy emission unit with respect to a three-dimensional workpiece, wherein the ejection of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism are all performed simultaneously. and a second operation that follows the first operation in the same printing pass as the first operation, in which the energy emission unit emits energy to the workpiece and the movement mechanism moves the head and the energy emission unit relative to the workpiece simultaneously, but does not eject liquid onto the workpiece by the head, wherein a first irradiation distance, which is the distance between the workpiece and the emission surface along the normal direction of the emission surface during the first operation, and a second irradiation distance, which is the distance between the workpiece and the emission surface along the normal direction of the emission surface during the second operation, are different from each other.

[0006] Another aspect of the three-dimensional object printing method according to the present disclosure is a three-dimensional object printing method using a head having an ejection surface provided with nozzles that eject liquid, an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head, and a movement mechanism that changes the relative positions of the head and the energy emission unit with respect to a three-dimensional workpiece, wherein the ejection of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism are simultaneously performed. and a second operation that follows the first operation in the same printing pass as the first operation, in which the energy output unit outputs energy to the workpiece and the movement mechanism moves the head and the energy output unit relative to the workpiece simultaneously, but does not eject liquid onto the workpiece, wherein a first angle, which is the angle between the ejection surface and a surface of the workpiece facing the ejection surface during the first operation, and a second angle, which is the angle between the ejection surface and a surface of the workpiece facing the ejection surface during the second operation, are different from each other.

[0007] One aspect of a three-dimensional object printing device according to the present disclosure includes a head having an ejection surface provided with nozzles that eject liquid, an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head, and a movement mechanism that changes the relative positions of the head and the energy emission unit with respect to a three-dimensional workpiece, and includes a first operation that simultaneously executes ejection of liquid onto the workpiece by the head, emission of energy onto the workpiece by the energy emission unit, and relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; A second operation is performed following the first operation in the same printing pass as the first operation, in which the energy emission unit emits energy to the workpiece and the movement mechanism moves the head and the energy emission unit relative to the workpiece, and the head does not eject liquid onto the workpiece, and a first irradiation distance, which is the distance between the workpiece and the emission surface along the normal direction of the emission surface during the first operation, and a second irradiation distance, which is the distance between the workpiece and the emission surface along the normal direction of the emission surface during the second operation, are different from each other. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing an outline of a three-dimensional object printing device according to a first embodiment. FIG. [Figure 2] FIG. 1 is a block diagram showing the electrical configuration of a three-dimensional object printing device according to a first embodiment. [Figure 3] FIG. 2 is a perspective view showing a schematic configuration of a head unit. [Figure 4] 3 is a flowchart showing a three-dimensional object printing method according to the first embodiment. [Figure 5] FIG. 10 is a diagram for explaining teaching of a robot. [Figure 6] 10A and 10B are diagrams for explaining a discharge distance and an irradiation distance. [Figure 7] FIG. 4 is a diagram for explaining a first operation in the first embodiment. [Figure 8]FIG. 10 is a diagram for explaining a second operation in the first embodiment. [Figure 9] FIG. 10 is a diagram for explaining a second operation in the second embodiment. [Figure 10] FIG. 11 is a diagram for explaining a second operation in the third embodiment. [Figure 11] FIG. 13 is a diagram illustrating a second operation in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0010] For convenience, the following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following description, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Furthermore, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction.

[0011] Here, the X-axis, Y-axis, and Z-axis correspond to the coordinate axes of a world coordinate system set in a space in which the robot 2 (described later) is installed. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward vertical direction. A base coordinate system based on the position of a base 210 (described later) of the robot 2 is associated with the world coordinate system by calibration. For convenience, the following describes an example in which the operation of the robot 2 is controlled using the world coordinate system as the robot coordinate system.

[0012] The Z axis does not have to be a vertical axis. Furthermore, the X axis, Y axis, and Z axis are typically perpendicular to one another, but this is not a limitation and they may not be perpendicular. For example, the X axis, Y axis, and Z axis may intersect each other at an angle between 80° and 100°.

[0013] 1. First embodiment 1-1. Overview of the 3D printing device 1 is a perspective view showing an outline of a three-dimensional object printing apparatus 1 according to the first embodiment. The three-dimensional object printing apparatus 1 is an apparatus that performs printing on the surface of a three-dimensional workpiece W by an inkjet method.

[0014] The workpiece W has a surface WF to be printed. In the example shown in FIG. 1, the workpiece W is a rectangular parallelepiped, and the surface WF is flat. During printing, the workpiece W is supported as needed by a structure such as a predetermined installation table, robot hand, or conveyor. The shape, size, etc. of the workpiece W or the surface WF are not limited to the example shown in FIG. 1 and are arbitrary. For example, the surface WF may have a curved or bent portion. Furthermore, the position or posture of the workpiece W or the surface WF during printing may be arbitrary as long as it is printable and is not limited to the example shown in FIG. 1.

[0015] As shown in Figure 1, the three-dimensional object printing apparatus 1 has a robot 2, which is an example of a "movement mechanism," a head unit 3, a controller 5, a piping section 10, and a wiring section 11. Below, we will first briefly explain each of these in order.

[0016] The robot 2 is a robot that changes the position and posture of the head unit 3 in the world coordinate system. In the example shown in Fig. 1, the robot 2 is a so-called six-axis vertical articulated robot.

[0017] As shown in FIG. 1, the robot 2 has a base 210 and an arm 220.

[0018] Base 210 is a platform that supports arm 220. In the example shown in Fig. 1, base 210 is fixed by screws or the like to an installation surface such as a floor surface or a base facing in the Z1 direction. The installation surface to which base 210 is fixed may be a surface facing any direction and is not limited to the example shown in Fig. 1, and may be, for example, a wall, a ceiling, a surface of a movable cart, or the like.

[0019] Arm 220 is a six-axis robot arm having a base end attached to base 210 and a tip end that changes position and posture three-dimensionally relative to the base end. Specifically, arm 220 has arms 221, 222, 223, 224, 225, and 226, also called links, which are connected in this order.

[0020] The arm 221 is connected to the base 210 via a joint 230_1 so as to be rotatable around a rotation axis O1. The arm 222 is connected to the arm 221 via a joint 230_2 so as to be rotatable around a rotation axis O2. The arm 223 is connected to the arm 222 via a joint 230_3 so as to be rotatable around a rotation axis O3. The arm 224 is connected to the arm 223 via a joint 230_4 so as to be rotatable around a rotation axis O4. The arm 225 is connected to the arm 224 via a joint 230_5 so as to be rotatable around a rotation axis O5. The arm 226 is connected to the arm 225 via a joint 230_6 so as to be rotatable around a rotation axis O6.

[0021] Each of the joints 230_1 to 230_6 is an example of a "rotating portion," and is a mechanism that rotatably connects one of two adjacent members among the base 210 and the arms 221 to 226 to the other. Note that, hereinafter, each of the joints 230_1 to 230_6 may be referred to as a "joint 230."

[0022] Although not shown in Fig. 1, each of the joints 230_1 to 230_6 is provided with a drive mechanism that rotates one of the two corresponding adjacent members relative to the other. The drive mechanism includes, for example, a motor that generates a drive force for the rotation, a reducer that reduces and outputs the drive force, and an encoder such as a rotary encoder that detects an amount of movement such as the angle of the rotation. The assembly of the drive mechanisms of the joints 230_1 to 230_6 corresponds to an arm drive mechanism 2a shown in Fig. 2, which will be described later.

[0023] The rotation axis O1 is an axis perpendicular to an installation surface (not shown) 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.

[0024] Regarding these rotation axes, "perpendicular" refers not only to the case where the angle between the two rotation axes is exactly 90°, but also to the case where the angle between the two rotation axes is deviated from 90° within a range of about ±5°. Similarly, "parallel" refers not only to the case where the two rotation axes are strictly parallel, but also to the case where one of the two rotation axes is inclined relative to the other within a range of about ±5°.

[0025] A head unit 3 is attached as an end effector to the arm 226 located at the most distal end of the arm section 220 of the robot 2, and is fixed thereto by screws or the like.

[0026] The head unit 3 is an assembly having a head 3a that ejects ink, which is an example of a "liquid," toward the workpiece W. In this embodiment, the head unit 3 has a pressure adjustment valve 3b and an energy emission unit 3c in addition to the head 3a. Details of the head unit 3 will be described later with reference to FIG. 3.

[0027] The ink is not particularly limited, and examples thereof include water-based inks in which a coloring material such as a dye or pigment is dissolved in an aqueous solvent, curable inks using curable resins such as UV-curable inks, and solvent-based inks in which a coloring material such as a dye or pigment is dissolved in an organic solvent. Among these, curable inks are preferred. The curable ink is not particularly limited, and may be, for example, a heat-curable ink, a photocurable ink, a radiation-curable ink, or an electron beam-curable ink. Photocurable inks such as UV-curable inks are preferred. The ink is not limited to a solution, but may also be an ink in which a coloring material or the like is dispersed as a dispersoid in a dispersion medium. The ink is also not limited to an ink containing a coloring material, and may also be, for example, an ink containing conductive particles such as metal particles as a dispersoid for forming wiring, a clear ink, or a treatment liquid for surface treatment of the workpiece W.

[0028] A piping section 10 and a wiring section 11 are connected to the head unit 3. The piping section 10 is a piping or a group of piping that supplies ink from an ink tank (not shown) to the head unit 3. The wiring section 11 is a wiring or a group of wiring that supplies an electrical signal that drives the head 3a.

[0029] The controller 5 is a robot controller that controls the driving of the robot 2. Below, the electrical configuration of the three-dimensional object printing apparatus 1 will be described with reference to FIG. 2, including a detailed description of the controller 5.

[0030] 1-2. Electrical configuration of the 3D printing device Fig. 2 is a block diagram showing the electrical configuration of the three-dimensional object printing apparatus 1 according to the first embodiment. Fig. 2 shows the electrical components of the three-dimensional object printing apparatus 1. As shown in Fig. 2, in addition to the components shown in Fig. 1, the three-dimensional object printing apparatus 1 also has a control module 6 communicatively connected to a controller 5, and a computer 7 communicatively connected to the controller 5 and the control module 6.

[0031] 2 may be divided appropriately, some may be included in other components, or may be integrated with other components. For example, some or all of the functions of the controller 5 or control module 6 may be implemented by a computer 7, or may be implemented by another external device such as a PC (personal computer) connected to the controller 5 via a network such as a LAN (Local Area Network) or the Internet.

[0032] The controller 5 has a function of controlling the driving of the robot 2 and a function of generating a signal D3 for synchronizing the ink ejection operation of the head unit 3 with the operation of the robot 2.

[0033] The controller 5 includes a memory circuit 5a and a processing circuit 5b.

[0034] The storage circuit 5a stores various programs executed by the processing circuit 5b and various data processed by the processing circuit 5b. The storage circuit 5a includes, for example, one or both of semiconductor memories: a volatile memory such as a random access memory (RAM) and a nonvolatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). Note that part or all of the storage circuit 5a may be included in the processing circuit 5b.

[0035] The memory circuit 5a stores teaching point information Da and path information Db. The teaching point information Da is information indicating multiple positions on the path along which the head unit 3 should move and the attitude of the head unit 3 at each of the multiple positions. The teaching point information Da is generated based on information acquired by, for example, direct teaching or offline teaching. The teaching point information Da is expressed using, for example, coordinate values in a base coordinate system or a world coordinate system. The path information Db is information indicating the path along which the head unit 3 should move and the attitude of the head unit 3 on that path. The path information Db is generated using the teaching point information Da. More specifically, the path information Db is generated using, for example, the shape of the workpiece W in addition to the teaching point information Da. The path information Db is expressed using, for example, coordinate values in a base coordinate system or a world coordinate system. The shape of the workpiece W is determined, for example, from CAD (computer-aided design) data indicating the three-dimensional shape of the workpiece W. The above-mentioned route information Db is input from the computer 7 to the storage circuit 5a.

[0036] The processing circuit 5b controls the operation of the arm driving mechanism 2a of the robot 2 based on the path information Db and generates a signal D3. The processing circuit 5b includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the processing circuit 5b may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU.

[0037] Here, the arm driving mechanism 2a is an assembly of driving mechanisms for the aforementioned joints 230_1 to 230_6, and each joint has a motor for driving the joint of the robot 2 and an encoder for detecting the rotation angle of the joint of the robot 2.

[0038] The processing circuit 5b performs inverse kinematics calculations, which are calculations that convert the path information Db into movement quantities such as the rotation angle and rotation speed of each joint of the robot 2. The processing circuit 5b then outputs a control signal Sk1 based on the output D1 from each encoder of the arm driving mechanism 2a so that the movement quantities such as the actual rotation angle and rotation speed of each joint match the aforementioned calculation results based on the path information Db. The control signal Sk1 is a signal for controlling the driving of the motor of the arm driving mechanism 2a. Here, the control signal Sk1 is corrected by the processing circuit 5b as necessary based on the output from a distance sensor (not shown).

[0039] Furthermore, the processing circuit 5b generates a signal D3 based on an output D1 from at least one of the multiple encoders of the arm drive mechanism 2a. For example, the processing circuit 5b generates, as the signal D3, a trigger signal including a pulse at the timing when the output D1 from one of the multiple encoders reaches a predetermined value.

[0040] The control module 6 is a circuit that controls the ink ejection operation of the head unit 3 based on the signal D3 output from the controller 5 and print data from the computer 7. The control module 6 has a timing signal generation circuit 6a, a power supply circuit 6b, a control circuit 6c, and a drive signal generation circuit 6d.

[0041] The timing signal generating circuit 6a generates a timing signal PTS based on the signal D3. The timing signal generating circuit 6a is configured, for example, with a timer that starts generating the timing signal PTS when the signal D3 is detected.

[0042] The power supply circuit 6b receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied appropriately to the control module 6 and each component of the head unit 3. For example, the power supply circuit 6b generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the head unit 3. The power supply potential VHV is also supplied to the drive signal generation circuit 6d.

[0043] The control circuit 6c generates a control signal SI, a waveform designation signal dCom, a latch signal LAT, a clock signal CLK, and a change signal CNG based on the timing signal PTS. These signals are synchronized with the timing signal PTS. Of these signals, the waveform designation signal dCom is input to the drive signal generation circuit 6d, and the other signals are input to the switch circuit 3e of the head unit 3.

[0044] The control signal SI is a digital signal that specifies the operating state of the drive elements of the head 3a of the head unit 3. Specifically, the control signal SI specifies whether or not to supply a drive signal Com (described below) to the drive element based on the print data. This specification, for example, specifies whether or not to eject ink from the nozzle corresponding to the drive element, or specifies the amount of ink ejected from the nozzle. The waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The latch signal LAT and change signal CNG are used in conjunction with the control signal SI to specify the drive timing of the drive element, thereby specifying the timing of ink ejection from the nozzle. The clock signal CLK is a reference clock signal synchronized with the timing signal PTS.

[0045] The control circuit 6c includes, for example, one or more processors such as CPUs (Central Processing Units). Note that the control circuit 6c may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU.

[0046] The drive signal generation circuit 6d is a circuit that generates a drive signal Com for driving each drive element of the head 3a of the head unit 3. Specifically, the drive signal generation circuit 6d includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 6d, the DA conversion circuit converts the waveform designation signal dCom from the control circuit 6c from a digital signal to an analog signal, and the amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 6b to generate the drive signal Com. Here, of the waveforms included in the drive signal Com, the signal with 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 6d to the drive element via the switch circuit 3e of the head unit 3.

[0047] Here, the switch circuit 3e is a circuit including a switching element that switches whether or not at least a part of the waveform included in the drive signal Com is to be supplied as the drive pulse PD based on the control signal SI.

[0048] The computer 7 has a function of supplying information such as teaching point information Da and path information Db to the controller 5, and a function of supplying information such as print data to the control module 6. In addition to these functions, the computer 7 of this embodiment also has a function of controlling the driving of the energy emitter 3c and a function of generating teaching point information Da and path information Db. The computer 7 is, for example, a desktop or notebook computer on which programs that realize these functions are installed.

[0049] 1-3.Head unit configuration FIG. 3 is a perspective view showing a schematic configuration of the head unit 3. For convenience, the following description will be made using the mutually intersecting a-axis, b-axis, and c-axis as appropriate. In the following description, one direction along the a-axis is the a1 direction, and the direction opposite the a1 direction is the a2 direction. Similarly, the opposite directions along the b-axis are the b1 direction and the b2 direction. Furthermore, the opposite directions along the c-axis are the c1 direction and the c2 direction.

[0050] 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 posture relationship with the world coordinate system or robot coordinate system changes depending on the operation of the robot 2. In the example shown in FIG. 3, the c-axis is an axis parallel to the rotation axis O6. The a-axis, b-axis, and c-axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°. The tool coordinate system and the base coordinate system or the robot coordinate system are associated by calibration. The tool coordinate system is set, for example, so that the center of the ejection surface FN (described later) serves as the reference (TCP: tool center point).

[0051] As described above, the head unit 3 has a head 3a, a pressure adjustment valve 3b, and an energy emission unit 3c. These are supported by a support 3f indicated by a two-dot chain line in FIG. 3. In the example shown in FIG. 3, the head unit 3 has one head 3a and one pressure adjustment valve 3b, but the numbers are not limited to those shown in FIG. 3 and may be two or more. In addition, the installation position of the pressure adjustment valve 3b is not limited to the arm 226 and may be, for example, another arm or the like, or may be in a fixed position relative to the base 210.

[0052] The support 3f is made of, for example, a metal material, etc., and is substantially rigid. Although the support 3f is shown in Fig. 3 as having a flat box shape, the shape of the support 3f is not particularly limited and may be any shape.

[0053] The support 3f is attached to the arm 226. Therefore, the head 3a, the pressure adjustment valve 3b, and the energy output unit 3c are collectively supported on the arm 226 by the support 3f. Therefore, the relative positions of the head 3a, the pressure adjustment valve 3b, and the energy output unit 3c with respect to the arm 226 are fixed. In the example shown in FIG. 3, the pressure adjustment valve 3b is disposed at a position in the c1 direction with respect to the head 3a. The energy output unit 3c is disposed at a position in the a2 direction with respect to the head 3a.

[0054] The head 3a has an ejection surface FN and multiple nozzles N opening on the ejection surface FN. The ejection surface FN is the nozzle surface on which the nozzles N open, and is configured, for example, as the surface of a nozzle plate in which the nozzles N are provided as through-holes in a plate-like member made of a material such as silicon (Si) or metal. In the example shown in FIG. 3, the normal direction of the ejection surface FN is the c2 direction, and the multiple nozzles N are divided into nozzle rows L1 and L2 arranged at intervals along the a-axis. Each of the nozzle rows L1 and L2 is a collection of multiple nozzles N linearly arranged along the b-axis. Here, elements associated with each nozzle N in the nozzle row L1 and elements associated with each nozzle N in the nozzle row L2 in the head 3a are configured substantially symmetrically to each other along the a-axis. Furthermore, the arrangement direction DN, described below, is parallel to the b-axis.

[0055] However, the positions of the multiple nozzles N in nozzle row L1 and the multiple nozzles N in nozzle row L2 in the direction along the b-axis may or may not match. Also, elements related to each nozzle N in one of nozzle row L1 and nozzle row L2 may be omitted. Below, a configuration in which the positions of the multiple nozzles N in nozzle row L1 and the multiple nozzles N in nozzle row L2 in the direction along the b-axis match will be exemplified.

[0056] Although not shown, the head 3a has a piezoelectric element serving as a drive element and a cavity for storing ink for each nozzle N. Here, the piezoelectric element changes the pressure in the cavity corresponding to the piezoelectric element, thereby ejecting ink from the nozzle corresponding to the cavity. Such a head 3a can be obtained, for example, by bonding together, with an adhesive, multiple substrates such as silicon substrates that have been appropriately processed by etching or the like. Note that instead of the piezoelectric element, a heater that heats the ink in the cavity may be used as the drive element for ejecting ink from the nozzle.

[0057] As described above, ink is supplied to the head 3a from an ink tank (not shown) via the supply pipe 10a. A pressure adjustment valve 3b is interposed between the supply pipe 10a and the head 3a.

[0058] The pressure adjustment valve 3b is a valve mechanism that opens and closes according to the pressure of the ink inside the head 3a. This opening and closing maintains the ink pressure inside the head 3a at a negative pressure within a predetermined range, even if the positional relationship between the head 3a and the ink tank (not shown) changes. This stabilizes the ink meniscus formed in the nozzle N of the head 3a. As a result, air bubbles are prevented from entering the nozzle N and ink is prevented from overflowing from the nozzle N. Ink from the pressure adjustment valve 3b is appropriately distributed to multiple locations in the head 3a via branch flow paths (not shown). Here, ink from an ink tank (not shown) is transferred into the supply pipe 10a at a predetermined pressure by a pump or the like.

[0059] The energy emitter 3c emits energy such as light, heat, electron beams, or radiation to harden or solidify the ink on the workpiece W. For example, if the ink is ultraviolet-curable, the energy emitter 3c is configured with a light-emitting element such as an LED (light emitting diode) that emits ultraviolet light. The energy emitter 3c may also include optical components such as lenses for adjusting the energy emission direction or emission range, as appropriate.

[0060] The energy emitter 3c does not have to completely cure or completely solidify the ink on the workpiece W. In this case, for example, the ink may be completely cured or completely solidified after being irradiated with energy from the energy emitter 3c using energy from a curing light source that is separately installed on the installation surface of the base 210 of the robot 2.

[0061] 1-4. Three-dimensional object printing method 4 is a flowchart showing the three-dimensional object printing method according to the first embodiment. The three-dimensional object printing method will be described below using the three-dimensional object printing device 1 described above as an example.

[0062] The three-dimensional object printing method shown in Figure 4 includes step S10 of acquiring teaching point information Da, step S20 of generating path information Db using the teaching point information Da, and step S30 of performing a printing operation using the path information Db. Here, step S30 includes a first operation S31 and a second operation S32. In the first operation S31, the robot 2 changes the positions of the head 3a and the energy emitter 3c, while ejecting ink from the head 3a and irradiating energy from the energy emitter 3c onto the workpiece W. In the second operation S32, the robot 2 changes the positions of the head 3a and the energy emitter 3c, while irradiating energy from the energy emitter 3c onto the workpiece W without ejecting ink from the head 3a. Each step will be described below.

[0063] Fig. 5 is a diagram for explaining teaching of the robot 2. Fig. 5 illustrates a case where first teaching points PT1_1 to PT_3 and a second teaching point PT2 are used as teaching points. Below, the first teaching points PT1_1 to PT1_3 may be referred to as the first teaching point PT1 without distinction. Note that below, an example is given of a case where the movement path RU of the head unit 3 is taught with the center of the ejection surface FN as TCP.

[0064] First, a description will be given of the movement path RU of the head 3a to be taught to the robot 2 in step S10. Fig. 5 illustrates a case where the surface WF of the workpiece W is a plane perpendicular to the Z axis, and the workpiece W is placed at a position further in the X2 direction than the robot 2.

[0065] In the printing operation in step S30 described below, the robot 2 operates three of the six joints 230. In the example shown in Fig. 5, during the printing operation, the robot 2 operates the joints 230_2, 230_3, and 230_5 while the rotation axes of these joints are parallel to the Y axis. In this way, the operation of the three joints 230 allows the head 3a to stably move along the movement path RU.

[0066] The movement path RU is the path from position P1 to position P3. When viewed in the Z2 direction, the movement path RU is a straight line extending along the X axis. Furthermore, the movement path RU is divided by position P2 into a path from position P1 to position P2 and a path from position P2 to position P3. The path from position P1 to position P2 is the movement path of the head 3a in the first operation S31. The path from position P2 to position P3 is the movement path of the head 3a in the second operation S32. Here, the length of the movement path of the head 3a in the second operation S32 is shorter than the length of the movement path of the head 3a in the first operation S31.

[0067] Furthermore, the distance between the path from position P1 to position P2 and the surface WF is set to be constant. Therefore, the path from position P1 to position P2 is a path that follows the surface WF. In contrast, the distance between the path from position P2 to position P3 that follows the surface WF and the surface WF changes as one moves from position P2 to position P3. Therefore, the path from position P2 to position P3 is a path that does not follow the surface WF. In this embodiment, the distance between the path from position P2 to position P3 that follows the surface WF and the surface WF increases as one moves from position P2 to position P3.

[0068] In step S10, information regarding the posture of the arm 220 of the robot 2 when the center of the discharge surface FN is positioned at each of the first teaching point PT1 and the second teaching point PT2 is obtained by online teaching, offline teaching, etc. Using this information, teaching point information Da is generated.

[0069] The first teaching point PT1 is a teaching point for the first operation S31, and is located on a path along the plane WF from position P1 to position P2. In the example shown in FIG. 5, the first teaching point PT1_1 is position P1, the first teaching point PT1_2 is a position between positions P1 and P2, and the first teaching point PT1_3 is position P2. Note that the number of first teaching points PT1 is not limited to three and may be two or four or more. Furthermore, the position of the first teaching point PT1_1 may be a position different from position P1, and the position of the first teaching point PT1_3 may be a position different from position P2.

[0070] The second teaching point PT2 is a teaching point for the second operation S32 and is located on the path from position P2 to position P3. In the example shown in FIG. 5, the second teaching point PT2 is position P3. The number of second teaching points PT2 is not limited to one and may be two or more. The position of the second teaching point PT2 may be a position different from position P3. However, since ink is not ejected from the head 3a in the second operation S32, it is preferable that the number of second teaching points PT2 be smaller than the number of first teaching points PT1 in order to simplify the teaching work.

[0071] Using the first teaching point PT1 and the second teaching point PT2 as described above, teaching point information Da is obtained. The obtained teaching point information Da is used to generate path information Db in step S20. That is, in step S20, as described above, the path information Db is generated using, for example, CAD (computer-aided design) data indicating the three-dimensional shape of the workpiece W in addition to the teaching point information Da.

[0072] Before describing the first operation S31 and the second operation S32, the discharge distance La and the irradiation distance Lb will be described below with reference to FIG.

[0073] FIG. 6 is a diagram illustrating the discharge distance La and the irradiation distance Lb. For ease of explanation, FIG. 6 shows a state in which the attitude of the head unit 3 is tilted so that the discharge surface FN and the emission surface FL are non-parallel to the surface WF of the workpiece W. In the example shown in FIG. 6, the discharge surface FN and the emission surface FL are parallel to each other, and the angle θa between the surface WF and the discharge surface FN is equal to the angle θb between the surface WF and the emission surface FL. Note that the discharge surface FN and the emission surface FL do not have to be parallel to each other. In this case, the angles θa and θb are different from each other.

[0074] The ejection distance La is the distance between the workpiece W and the ejection surface FN along the normal direction of the ejection surface FN. In other words, when a normal line extending from the center Pa1 of the ejection surface FN intersects with the surface WF of the workpiece W at the intersection Pa2, the ejection distance La is the distance from the center Pa1 to the intersection Pa2. Also, as shown by the two-dot chain line in FIG. 6, when the normal line extending from the center Pa1 of the ejection surface FN does not intersect with the surface of the workpiece W, the intersection point Pa2 is the normal line extending from the center Pa1 of the ejection surface FN and the imaginary plane FV extending from the surface WF of the workpiece W. Note that when the normal line extending from the center Pa1 of the ejection surface FN does not intersect with the imaginary plane FV, such as when the normal line extending from the center Pa1 of the ejection surface FN is parallel to the imaginary plane FV, the ejection distance La is infinite. Here, the ejection direction of ink from the nozzle N is parallel to the normal direction of the ejection surface FN under ideal conditions.

[0075] The irradiation distance Lb is the distance between the workpiece W and the emission surface FL along the normal direction of the emission surface FL. In other words, when a normal extending from the center Pb1 of the emission surface FL intersects with the surface WF of the workpiece W at the intersection Pb2, the irradiation distance Lb is the distance from the center Pb1 to the intersection Pb2. Furthermore, as shown by the two-dot chain line in FIG. 6, when the normal extending from the center Pb1 of the emission surface FL does not intersect with the surface of the workpiece W, the intersection point Pb2 is the point where the normal extending from the center Pb1 of the emission surface FL intersects with the imaginary plane FV extending from the surface WF of the workpiece W. Note that when the normal extending from the center Pb1 of the emission surface FL does not intersect with the imaginary plane FV, such as when the normal extending from the center Pb1 of the emission surface FL is parallel to the imaginary plane FV, the irradiation distance Lb is infinite.

[0076] In the example shown in FIG. 5, the surface WF of the workpiece W is flat, so the angle θa is defined as the angle between the discharge surface FN and the surface of the workpiece W facing the discharge surface FN. On the other hand, if the surface of the workpiece W is curved, the angle θa is defined as the angle between the discharge surface FN and a virtual tangent plane set at the intersection Pa2 between the normal line extending from the center Pa1 of the discharge surface FN and the surface of the workpiece W. Here, the virtual tangent plane can also be said to be a virtual surface that approximates the portion of the surface of the workpiece W facing the discharge surface FN. However, if the normal line extending from the center Pa1 of the discharge surface FN does not intersect with the surface of the workpiece W, the angle θa is the angle between the discharge surface FN and a virtual plane FV extending from the surface of the workpiece W.

[0077] 7 is a diagram illustrating the first operation S31 in the first embodiment. In the first operation S31, as shown in FIG. 7, the robot 2 moves the position of the head 3a from position P1 to position P2. At this time, the head 3a ejects ink onto the workpiece W based on image data, and the energy emitter 3c emits energy LL onto the workpiece W. At this time, the head 3a moves from position P1 to position P2 while being positioned forward of the energy emitter 3c. Therefore, the energy LL from the energy emitter 3c is irradiated onto the ink applied onto the workpiece W by the head 3a.

[0078] However, during the execution of the first operation S31, the irradiation range RL1, which is the maximum range over which the energy LL is irradiated onto the workpiece W, does not coincide with the printing range RP, which is the maximum range over which ink is applied to the workpiece W. Here, after the execution of the first operation S31, there is an area RN on the workpiece W where ink that is not irradiated with the energy LL may remain. The area RN is an area where ink that was last ejected from the head 3a during the execution of the first operation S31 may remain.

[0079] From the viewpoint of improving image quality, it is preferable that the first discharge distance La1, which is the discharge distance La during the execution of the first operation S31, be constant throughout the execution period of the first operation S31. Here, the concept of the first discharge distance La1 being constant means that errors due to irregularities formed on the surface WF and the operation of the robot 2 are allowed. From a similar viewpoint, it is also preferable that the first angle θa1, which is the angle θa during the execution of the first operation S31, be constant throughout the execution period of the first operation S31. Here, the concept of the first angle θa1 being constant means that errors due to irregularities formed on the surface WF and the operation of the robot 2 are allowed. When the first discharge distance La1 and the first angle θa1 are both constant throughout the execution period of the first operation S31, the first irradiation distance Lb1, which is the irradiation distance Lb during the execution of the first operation S31, is constant throughout the execution period of the first operation S31.

[0080] 7, the ejection surface FN is parallel to the surface WF, and the first angle θa1 is 0°. Note that the first angle θa1 may be greater or less than 0°, but is preferably ±45° or less from the viewpoint of improving image quality.

[0081] In the first operation S31 of this embodiment, the head 3a is moved from position P1 to position P2 while maintaining the first discharge distance La1 and the first angle θa1 constant throughout the execution period of the first operation S31 by the operation of the joints 230_2, 230_3, and 230_5 of the robot 2. Note that, in the first operation S31, the joints 230 of the robot 2 other than the joints 230_2, 230_3, and 230_5 may be operated; however, by not operating the joints 230 other than the joints 230_2, 230_3, and 230_5, the movement of the head 3a can be performed with high precision.

[0082] 8 is a diagram illustrating the second operation S32 in the first embodiment. In the second operation S32, as shown in FIG. 8, the robot 2 moves the position of the head 3a from position P2 to position P3. At this time, the head 3a does not eject ink onto the workpiece W, and the energy emitter 3c emits energy LL onto the workpiece W. Therefore, the energy LL from the energy emitter 3c is irradiated onto the ink remaining in the aforementioned region RN of the workpiece W. In other words, during the execution of the second operation S32, the irradiation range RL2, which is the maximum range over which the energy LL is irradiated onto the workpiece W, encompasses the region RN.

[0083] Here, the second operation S32 is performed following the first operation S31 in the same printing pass as the first operation S31. The "printing pass" refers to a series of operations that executes the ejection of ink by the head 3a and the emission of energy by the energy emission unit 3c, without including either a line feed operation that shifts the movement path of the head 3a in the width direction or a return operation that switches the movement direction of the head 3a to the opposite direction.

[0084] The second irradiation distance Lb2, which is the irradiation distance Lb during the execution of the second operation S32, differs from the first irradiation distance Lb1 described above for at least a portion of the period. In this embodiment, the second irradiation distance Lb2 is the same as the first irradiation distance Lb1 immediately after the start of the execution of the second operation S32, but becomes larger than the first irradiation distance Lb1 during the execution of the second operation S32. Here, the second irradiation distance Lb2 continuously increases as the head 3a moves from position P2 to position P3. In this manner, the amount of change in the second irradiation distance Lb2 is larger than the amount of change in the first irradiation distance Lb1. In other words, the amount of change in the first irradiation distance Lb1 is smaller than the amount of change in the second irradiation distance Lb2. Note that in this embodiment, although the head 3a does not eject ink during the execution of the second operation S32, the second ejection distance La2, which is the ejection distance La during the execution of the second operation S32, differs from the first ejection distance La1 described above due to the change in the second irradiation distance Lb2. That is, the second ejection distance La2 increases continuously as the head 3a moves from the position P2 to the position P3.

[0085] In the second operation S32 of the present embodiment, the head 3a is moved from the position P2 to the position P3 so as to increase the second irradiation distance Lb2 by the operation of the joint 230_5 of the robot 2. Note that in the second operation S32, a joint 230 other than the joint 230_5 of the robot 2 may be operated.

[0086] Here, the joint 230_5 is the joint 230 with the largest rotation amount during the execution of the second operation S32 among the plurality of joints 230. Among the rotation parts of the plurality of joints 230 that are closer to the base 210 than the joint 230_5, the joint 230 with the largest rotation amount during the execution of the first operation S31 is the joint 230_3. If the rotation amount of the joint 230_5 during the execution of the first operation S31 is R11, the rotation amount of the joint 230_3 during the execution of the first operation S31 is R12, the rotation amount of the joint 230_5 during the execution of the second operation S32 is R21, and the rotation amount of the joint 230_3 during the execution of the second operation S32 is R22, then the relationship R21 / R22>R11 / R12 is satisfied. Generally speaking, while the first operation S31 is being performed, the joint 230 is rotated as a whole, whereas while the second operation S32 is being performed, the joint 230 closest to the tip of the arm 220 is mainly rotated. Therefore, even when the arm 220 is fully extended by the first operation S31, it is possible to irradiate the region RN, where ink may remain and not be irradiated with the energy LL, with energy during the second operation S32. Furthermore, it is possible to reduce unnecessary operations of the robot 2 while performing the second operation S32, while controlling the position and orientation of the head 3a with high precision during the first operation S31.

[0087] The second angle θa2, which is the angle θa between the discharge surface FN and the surface of the workpiece W facing the discharge surface FN during the second operation S32, is different from the first angle θa1 described above. In this embodiment, the second angle θa2 is larger than the first angle θa1. Here, the second angle θa2 continuously increases as the head 3a moves from position P2 to position P3. In this way, the amount of change in the second angle θa2 is larger than the amount of change in the first angle θa1. In other words, the amount of change in the first angle θa1 is smaller than the amount of change in the second angle θa2.

[0088] The "amount of change in the first angle θa1" may be an average amount of change in the first angle θa1 over the period in which the first operation S31 is performed, or may be the difference between the maximum and minimum values of the first angle θa1 during the execution of the first operation S31. Similarly, the "amount of change in the second angle θa2" may be an average amount of change in the second angle θa2 over the period in which the second operation S32 is performed, or may be the difference between the maximum and minimum values of the second angle θa2 during the execution of the second operation S32.

[0089] In this embodiment, during the second operation S32, the posture of the head 3a changes so that the emission surface FL faces the movement direction of the head 3a during the execution of the first operation S31. That is, while the emission surface FL faces the Z2 direction at position P2, the direction in which the emission surface FL faces contains a larger component in the X2 direction at position P3. Here, the X2 direction is the movement direction of the head 3a during the execution of the first operation S31.

[0090] The relative movement speed of the energy emitter 3c with respect to the workpiece W during the execution of the second operation S32 is preferably equal to or less than the relative movement speed of the energy emitter 3c with respect to the workpiece W during the execution of the first operation S31. In this case, the density of the energy LL irradiated onto the ink on the workpiece W during the second operation S32 can be increased without increasing the intensity of the energy LL emitted from the energy emitter 3c. Note that the intensity of the energy LL emitted from the energy emitter 3c during the execution of the second operation S32 may be higher than that during the execution of the second operation S32.

[0091] Furthermore, the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the second operation S32 is smaller than the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the first operation S31. In other words, the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the first operation S31 is larger than the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the second operation S32.

[0092] Here, when the head 3a reaches position P3 from position P2, the three-dimensional object printing apparatus 1 finishes executing the second operation S32. After the second operation S32 is finished, it is preferable to stop emitting the energy LL from the energy emitter 3c.

[0093] The three-dimensional object printing method described above is performed using the three-dimensional object printing apparatus 1, as described above. As described above, the three-dimensional object printing apparatus 1 includes the head 3a, the energy emitter 3c, and the robot 2, which is an example of a "movement mechanism." The head 3a has an ejection surface FN equipped with nozzles N that eject ink, which is an example of a "liquid." The energy emitter 3c has an ejection surface FL that emits energy that hardens or solidifies the ink ejected from the head 3a. The robot 2 changes the relative positions of the head 3a and the energy emitter 3c with respect to the three-dimensional workpiece W.

[0094] The three-dimensional object printing apparatus 1 executes a first operation S31 and a second operation S32. That is, the three-dimensional object printing method using the three-dimensional object printing apparatus 1 includes the first operation S31 and the second operation S32.

[0095] The first operation S31 simultaneously executes the ejection of ink onto the workpiece W by the head 3a, the emission of energy onto the workpiece W by the energy emission unit 3c, and the relative movement of the head 3a and the energy emission unit 3c with respect to the workpiece W by the robot 2. The second operation S32 follows the first operation S31 in the same printing pass as the first operation S31, simultaneously executes the emission of energy onto the workpiece W by the energy emission unit 3c, and the relative movement of the head 3a and the energy emission unit 3c with respect to the workpiece W by the robot 2, but does not execute the ejection of ink onto the workpiece W by the head 3a.

[0096] In addition, the first irradiation distance Lb1, which is the distance between the workpiece W and the emission surface FL along the normal direction of the emission surface FL during the first operation S31, and the second irradiation distance Lb2, which is the distance between the workpiece W and the emission surface FL along the normal direction of the emission surface FL during the second operation S32, are different from each other.

[0097] In the three-dimensional object printing method or three-dimensional object printing device 1 described above, the first operation S31 simultaneously executes the ejection of ink onto the workpiece W by the head 3a and the relative movement of the head 3a and the energy emitter 3c relative to the workpiece W by the robot 2, thereby making it possible to apply ink over a required range of the workpiece W. Here, the first operation S31 simultaneously executes the emission of energy onto the workpiece W by the energy emitter 3c, making it possible to irradiate energy onto the ink on the workpiece W over most of the required range.

[0098] Furthermore, the second operation S32 is performed following the first operation S31 in the same printing pass as the first operation S31. Here, the second operation S32 simultaneously performs the emission of energy to the workpiece W by the energy emission unit 3c and the relative movement of the head 3a and the energy emission unit 3c with respect to the workpiece W by the robot 2, so that energy can be irradiated to ink that was applied to the workpiece W in the first operation S31 but was not irradiated with energy in the first operation S31. In other words, the second operation S32 can also irradiate energy to the ink that was last ejected from the head 3a during the execution of the first operation S31. Furthermore, because the second operation S32 does not execute the ejection of ink onto the workpiece W by the head 3a, ink that is not irradiated with energy is prevented from remaining on the workpiece W after the execution of the second operation S32.

[0099] Moreover, because the first irradiation distance Lb1 and the second irradiation distance Lb2 are different from each other, even if the movement of the robot 2 is restricted during the execution of the second operation S32 due to the range of movement of the robot 2 or the presence of an obstacle, it is possible to irradiate energy to the ink that remains on the workpiece W without being irradiated with energy after the execution of the first operation S31. In this way, the ink on the workpiece W can be appropriately cured or solidified.

[0100] Furthermore, as described above, the change amount of the first irradiation distance Lb1 is smaller than the change amount of the second irradiation distance Lb2. Therefore, the change amount of the first discharge distance La1 can be made smaller than the change amount of the second discharge distance La2. As a result, image quality can be improved compared to a configuration in which the change amount of the first discharge distance Lb1 is larger than the change amount of the second discharge distance Lb2. Note that, as described above, the first discharge distance La1 is the distance between the workpiece W and the discharge surface FN along the normal direction of the discharge surface FN during execution of the first operation S31. The second discharge distance La2 is the distance between the workpiece W and the discharge surface FN along the normal direction of the discharge surface FN during execution of the second operation S32.

[0101] As described above, it is preferable that the distance between at least a portion of the ejection surface FN and the workpiece W in the direction of ink ejection from the nozzle N during execution of the first operation S31, i.e., the first ejection distance La1, is constant throughout the execution period of the first operation S31. In this case, image quality can be easily improved. Note that if the surface of the workpiece W is curved or bent, it may not be possible to maintain a constant distance from the workpiece W over the entire ejection surface FN, which is substantially flat.

[0102] In the present embodiment, as described above, the second irradiation distance Lb2 is greater than the first irradiation distance Lb1. Therefore, if an object such as an obstacle is present on the workpiece W or ahead of it in the movement direction of the head 3a during the execution of the second operation S32, it is possible to irradiate the ink that remains on the workpiece W without being irradiated with energy after the execution of the first operation S31 while avoiding collision between the head 3a or the like and the object.

[0103] As described above, it is preferable that the relative movement speed of the energy emitter 3c with respect to the workpiece W during the execution of the second operation S32 be equal to or less than the relative movement speed of the energy emitter 3c with respect to the workpiece W during the execution of the first operation S31. In this case, even if the second irradiation distance Lb2 is greater than the first irradiation distance Lb1, it is possible to reduce the difference between the amount of energy imparted to the ink on the workpiece W during the execution of the first operation S31 and the amount of energy imparted to the ink on the workpiece W during the execution of the second operation S32.

[0104] In this embodiment, as described above, the first angle θa1, which is the angle between the discharge surface FN and the surface of the workpiece W facing the discharge surface FN during the first operation S31, and the second angle θa2, which is the angle between the discharge surface FN and the surface of the workpiece W facing the discharge surface FN during the second operation S32, are different from each other. Therefore, compared to when the first angle θa1 and the second angle θa2 are equal to each other, it is possible to make the first irradiation distance Lb1 and the second irradiation distance Lb2 different from each other while reducing the change in the positions of the head 3a and the energy emitter 3c.

[0105] As described above, when the change in the first angle θa1 is smaller than the change in the second angle θa2, it is easier to make the change in the first ejection distance La1 smaller than the change in the second ejection distance La2 than when the change in the first angle θa1 is larger than the change in the second angle θa2. Therefore, compared to a configuration in which the change in the first angle θa1 is larger than the change in the second angle θa2, this configuration has the advantage of making it easier to improve image quality.

[0106] The "amount of change in the first angle θa1" may be an average amount of change in the first angle θa1 over the period in which the first operation S31 is performed, or may be the difference between the maximum and minimum values of the first angle θa1 during the execution of the first operation S31. Similarly, the "amount of change in the second angle θa2" may be an average amount of change in the second angle θa2 over the period in which the second operation S32 is performed, or may be the difference between the maximum and minimum values of the second angle θa2 during the execution of the second operation S32.

[0107] Furthermore, as described above, when the first angle θa1 is constant throughout the execution period of the first operation S31, image quality can be improved compared to a configuration in which the first angle θa1 changes during execution of the first operation S31.

[0108] In this embodiment, as described above, in the second operation S32, the posture of the head 3a changes so that the emission surface FL faces the movement direction of the head 3a during execution of the first operation S31. Therefore, it is possible to irradiate energy over a wide area on the workpiece W during the second operation S32 while reducing the movement amount of the energy emission unit 3c during the second operation S32. Furthermore, when the arm 220 of the robot 2 is changed from a bent state to an extended state during a printing pass, it is possible to irradiate energy over a wide area on the workpiece W during the second operation S32 even when the arm 220 is fully extended.

[0109] Furthermore, as described above, the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the first operation S31 is greater than the relative movement distance of the head 3a or the energy emitter 3c with respect to the workpiece W during the second operation S32. This makes it possible to print over a wide range of the workpiece W while reducing unnecessary operations of the robot 2.

[0110] As described above, the three-dimensional object printing method includes a step of acquiring teaching point information Da before the first operation S31. The teaching point information Da is information regarding the first teaching points P1 for the first operation S31 and the second teaching points P2 for the second operation S32. Here, the number of second teaching points P2 is smaller than the number of first teaching points P1. Therefore, compared to when the number of second teaching points is greater than the number of first teaching points, generation of path information db regarding the movement path of the head 3a or the energy emitter 3c is simple.

[0111] As described above, the robot 2 has a base 210 and an arm 220 supported by the base 210. The head 3 a and the energy emitter 3 c are supported at the tip of the arm 220. The base 210 and the arm 220 are provided with a plurality of joints 230, which are an example of "a plurality of rotating units." The plurality of joints 230 change the position and posture of the head 3 a and the energy emitter 3 c relative to the base 210. Of the plurality of joints 230, the joint 230_5 having the largest amount of rotation during execution of the second operation S32 is an example of a "first rotating unit." Of the rotating units of the plurality of joints 230 that are closer to the base 210 than the joint 230_5, the joint 230_3 having the largest amount of rotation during execution of the first operation S31 is an example of a "second rotating unit." Here, if the rotation amount of the joint 230_5 during the first operation S31 is R11, the rotation amount of the joint 230_3 during the first operation S31 is R12, the rotation amount of the joint 230_5 during the second operation S32 is R21, and the rotation amount of the joint 230_3 during the second operation S32 is R22, then the relationship R21 / R22>R11 / R12 is satisfied. Therefore, even when the arm 220 is fully extended by the first operation S31, it is possible to irradiate the region RN, where ink may remain and not be irradiated with the energy LL, during the second operation S32. Furthermore, it is possible to reduce unnecessary movements of the robot 2 during the second operation S32 while controlling the position and posture of the head 3a with high precision during the first operation S31.

[0112] 2. Second embodiment A second embodiment of the present invention will be described below. In the following exemplary embodiment, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used and detailed descriptions of each element will be omitted as appropriate.

[0113] FIG. 9 is a diagram illustrating the second operation in the second embodiment. This embodiment is similar to the first embodiment described above, except for the second operation. The second operation in this embodiment is similar to the second operation S32 in the first embodiment, except that the attitude of the head unit 3 does not change. That is, in the second operation in this embodiment, the position of the head 3a changes from position P2 to position P3 while the attitudes of the head 3a and the energy emitter 3c remain constant. The second embodiment described above also allows the ink on the workpiece W to be appropriately cured or solidified. According to the second operation in this embodiment, for example, if there is an obstacle (not shown) on the X2 direction side of the workpiece W, it is possible to prevent the head unit 3 from colliding with the obstacle. Note that position P3 in this embodiment may be different from position P3 in the first embodiment.

[0114] 3. Third embodiment A third embodiment of the present invention will be described below. In the following exemplary embodiment, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used, and detailed descriptions of each element will be omitted as appropriate.

[0115] FIG. 10 is a diagram illustrating the second operation in the third embodiment. This embodiment is similar to the first embodiment described above, except for the second operation. The second operation in this embodiment is similar to the second operation S32 in the first embodiment, except that the orientation of the head unit 3 changes to the opposite side from that in the first embodiment. In this embodiment, the orientation of the head 3a in the second operation S32 changes so that the emission surface FL faces in the opposite direction to the movement direction of the head 3a during the execution of the first operation S31. That is, at position P2, the emission surface FL faces in the Z2 direction. In comparison, at position P3, the orientation of the emission surface FL includes a larger component in the X1 direction. Here, the X1 direction is the opposite direction to the movement direction of the head 3a during the execution of the first operation S31.

[0116] The third embodiment described above also allows the ink on the workpiece W to be appropriately cured or solidified. In this embodiment, in the second operation, the orientation of the head 3a changes so that the emission surface FL faces in the opposite direction to the movement direction of the head 3a during the first operation. Therefore, it is possible to irradiate the energy LL over a wide area on the workpiece W during the second operation while reducing the movement amount of the energy emission unit 3c during the second operation. It is also possible to reduce the amount of wasted energy irradiation on areas on the workpiece where no ink is present. Note that position P3 in this embodiment may be different from position P3 in the first embodiment.

[0117] 4. Fourth embodiment A fourth embodiment of the present invention will be described below. In the following exemplary embodiments, elements whose actions and functions are similar to those of the first embodiment will be designated by the same reference numerals as those used in the description of the first embodiment, and detailed descriptions of each element will be omitted where appropriate.

[0118] FIG. 11 is a diagram illustrating the second operation in the fourth embodiment. This embodiment is similar to the first embodiment described above, except for the second operation. The second operation of this embodiment is similar to the second operation S32 of the first embodiment, except that the orientation of the head unit 3 does not change and the second irradiation distance Lb2 is smaller than the first irradiation distance Lb1. In the example shown in FIG. 11, position P3 in the direction along the Z axis is located further in the Z2 direction than position P2 in the direction along the Z axis. In the second operation of this embodiment, the position of the head 3a changes from position P2 to position P3 while the orientations of the head 3a and the energy emitter 3c remain constant.

[0119] The second embodiment described above also makes it possible to appropriately harden or solidify the ink on the workpiece W. In this embodiment, as described above, the second irradiation distance Lb2 is shorter than the first irradiation distance Lb1. Therefore, the density of the energy LL irradiated onto the ink on the workpiece W in the second operation can be increased without increasing the intensity of the energy LL emitted from the energy emitter 3c. As a result, the ink on the workpiece W in the second operation can be sufficiently hardened or solidified without slowing down the movement speed of the energy emitter 3c in the second operation. Note that the distance from position P2 to position P3 in this embodiment may be different from the distance from position P2 to position P3 in the first embodiment.

[0120] 5. Variations Each of the above-mentioned exemplary embodiments can be modified in various ways. Specific modified embodiments that can be applied to each of the above-mentioned embodiments are exemplified below. Note that two or more embodiments arbitrarily selected from the following examples can be appropriately combined within the scope of not contradicting each other.

[0121] 5-1. Variation 1 In the above-described embodiment, a configuration using a six-axis vertical multi-axis robot is exemplified as the movement mechanism, but the movement mechanism is not limited to this configuration. The movement mechanism may be, for example, a vertical multi-axis robot other than a six-axis robot, or a horizontal multi-axis robot. Furthermore, the arm of the robot may have an extension mechanism or a linear motion mechanism in addition to a rotation unit configured with a rotation mechanism. However, from the viewpoint of balancing the print quality during printing operations and the degree of freedom of the robot's movement during non-printing operations, it is preferable that the robot be a multi-axis robot with six or more axes.

[0122] 5-2. Variation 2 In the above-described embodiment, the head is fixed to the robot using screws or the like, but is not limited to this. For example, the head may be fixed to the robot by gripping it with a gripping mechanism such as a hand attached as an end effector of the robot.

[0123] 5-3. Variation 3 In the above-described embodiment, a configuration in which printing is performed using one type of ink is exemplified, but this is not limited to this configuration, and the present disclosure can also be applied to a configuration in which printing is performed using two or more types of ink.

[0124] 5-4. Variation 4 The applications of the three-dimensional printing apparatus and three-dimensional printing method disclosed herein are not limited to printing. For example, a three-dimensional printing apparatus that ejects a color material solution is used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Also, a three-dimensional printing apparatus that ejects a conductive material solution is used as a manufacturing apparatus for forming wiring and electrodes on a wiring board. Furthermore, a three-dimensional printing apparatus can also be used as a jet dispenser that applies a liquid such as an adhesive to a medium. [Explanation of symbols]

[0125] 1...three-dimensional object printing device, 2...robot (movement mechanism), 2a...arm drive mechanism, 3...head unit, 3a...head, 3b...pressure adjustment valve, 3c...energy output unit, 3e...switch circuit, 3f...support, 5...controller, 5a...memory circuit, 5b...processing circuit, 6...control module, 6a...timing signal generation circuit, 6b...power supply circuit, 6c...control circuit, 6d...drive signal generation circuit, 7...computer, 10...piping section, 10a...supply pipe, 11...wiring section, 11a...drive wiring, 210...base, 220...arm section, 221...arm, 222...Arm, 223...Arm, 224...Arm, 225...Arm, 226...Arm, 230...Joint (rotating portion), 230_1...Joint (rotating portion), 230_2...Joint (rotating portion), 230_3...Joint (rotating portion, second rotating portion), 230_4...Joint (rotating portion), 230_5...Joint (rotating portion, first rotating portion), 230_6...Joint (rotating portion), CLK...Clock signal, CNG...Change signal, Com...Drive signal, D1...Output, D3...Signal, DN...Arrangement direction, Da...Teaching point information, Db...Path information, FL...Output surface, FN ...discharge surface, FV...virtual plane, L1...nozzle row, L2...nozzle row, LAT...latch signal, LL...energy, La...discharge distance, La1...first discharge distance, La2...second discharge distance, Lb...irradiation distance, Lb1...first irradiation distance, Lb2...second irradiation distance, N...nozzle, O1...rotation axis, O2...rotation axis, O3...rotation axis, O4...rotation axis, O5...rotation axis, O6...rotation axis, P1...first teaching point, P2...second teaching point, PD...drive pulse, PT1...first teaching point, PT1_1...first teaching point, PT1_2...first teaching point, PT1_3...first teaching point, PT 2...second teaching point, PTS...timing signal, Pa1...center, Pa2...intersection, Pb1...center, Pb2...intersection, RL1...irradiation range, RL2...irradiation range, RN...area, RP...printing range, RU...movement path, S10...step, S20...step, S30...step, S31...first operation, S32...second operation, SI...control signal, Sk1...control signal, VBS...offset potential, VHV...power supply potential, W...workpiece, WF...surface, dCom...waveform designation signal, db...path information, θa...angle, θa1...first angle, θa2...second angle, θb...angle.

Claims

1. a head having a discharge surface provided with nozzles for discharging liquid; an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head; a robot having a base and an arm supported by the base, the robot supporting the head and the energy emitter at the tip of the arm, and a movement mechanism that changes the relative position and orientation of the head and the energy emitter with respect to a three-dimensional workpiece, a first operation that simultaneously executes the discharge of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; a second operation subsequent to the first operation, in which the energy output unit outputs energy to the workpiece, and the movement mechanism moves the head and the energy output unit relative to the workpiece, but the head does not eject liquid onto the workpiece, a first irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the first operation, and a second irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the second operation, are different from each other; A three-dimensional object printing method.

2. In the second operation, the energy emission unit irradiates energy onto the liquid ejected last from the head during execution of the first operation. The three-dimensional object printing method according to claim 1 .

3. The amount of change in the first irradiation distance over the execution period of the first operation is smaller than the amount of change in the second irradiation distance over the execution period of the second operation.

3. The three-dimensional object printing method according to claim 1 or 2.

4. If the direction in which the liquid is ejected from the nozzle is defined as the ejection direction, The distance in the discharge direction between at least a portion of the discharge surface and the workpiece is is constant during the execution of the first operation; The three-dimensional object printing method according to any one of claims 1 to 3.

5. The second throw distance is smaller than the first throw distance. The method for printing a three-dimensional object according to any one of claims 1 to 4.

6. The second throw distance is greater than the first throw distance. The method for printing a three-dimensional object according to any one of claims 1 to 4.

7. a relative movement speed of the energy output unit with respect to the workpiece during the second operation is equal to or less than a relative movement speed of the energy output unit with respect to the workpiece during the first operation. The method for printing a three-dimensional object according to any one of claims 1 to 6.

8. a density of the energy irradiated from the energy output unit during the second operation is higher than a density of the energy irradiated from the energy output unit during the first operation; The method for printing a three-dimensional object according to any one of claims 1 to 7.

9. a head having a discharge surface provided with nozzles for discharging liquid; an energy emitting unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head; a movement mechanism that changes the relative positions of the head and the energy output unit with respect to a three-dimensional workpiece, a first operation that simultaneously executes the discharge of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; a second operation subsequent to the first operation, in which the energy output unit outputs energy to the workpiece, and the movement mechanism moves the head and the energy output unit relative to the workpiece, but the head does not eject liquid onto the workpiece, a first angle, which is an angle formed between the discharge surface and a surface of the workpiece facing the discharge surface during execution of the first operation, and a second angle, which is an angle formed between the discharge surface and a surface of the workpiece facing the discharge surface during execution of the second operation, are different from each other; A three-dimensional object printing method.

10. In the second operation, the energy emission unit irradiates energy onto the liquid ejected last from the head during execution of the first operation. The three-dimensional object printing method according to claim 9 .

11. A change in the first angle over a period during which the first operation is performed is smaller than a change in the second angle over a period during which the second operation is performed. The three-dimensional object printing method according to claim 9 or 10.

12. the first angle is constant throughout a period during which the first movement is performed; The method for printing a three-dimensional object according to any one of claims 9 to 11.

13. In the second operation, the attitude of the head is changed so that the emission surface faces the moving direction of the head during the execution of the first operation. The method for printing a three-dimensional object according to any one of claims 9 to 12.

14. In the second operation, the posture of the head is changed so that the emission surface faces in a direction opposite to the moving direction of the head during the execution of the first operation. The method for printing a three-dimensional object according to any one of claims 9 to 12.

15. a relative movement distance of the head or the energy output unit with respect to the workpiece during the first operation is greater than a relative movement distance of the head or the energy output unit with respect to the workpiece during the second operation. The method for printing a three-dimensional object according to any one of claims 1 to 14.

16. The relative position of the energy output portion with respect to the tip of the arm portion is fixed. The method for printing a three-dimensional object according to any one of claims 1 to 8.

17. A head having an ejection surface provided with nozzles for ejecting liquid; an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head; a moving mechanism that is a robot that changes the relative positions of the head and the energy output unit with respect to a three-dimensional workpiece, a first operation that simultaneously executes the discharge of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; a second operation following the first operation, in which the energy output unit outputs energy to the workpiece, and the movement mechanism moves the head and the energy output unit relative to the workpiece, without discharging liquid from the head to the workpiece; acquiring, before the first operation, teaching point information regarding a first teaching point for the first operation and a second teaching point for the second operation; the number of the second teaching points is less than the number of the first teaching points; a first irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the first operation, and a second irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the second operation, are different from each other; A three-dimensional object printing method.

18. A head having an ejection surface provided with nozzles for ejecting liquid; an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head; a movement mechanism that changes the relative positions of the head and the energy output unit with respect to a three-dimensional workpiece, a first operation that simultaneously executes the discharge of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; a second operation subsequent to the first operation, in which the energy output unit outputs energy to the workpiece, and the movement mechanism moves the head and the energy output unit relative to the workpiece, but the head does not eject liquid onto the workpiece, a first irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the first operation, and a second irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the second operation, are different from each other; the movement mechanism is a robot having a base and an arm supported by the base, the head and the energy output unit are supported at the tip of the arm, the base and the arm are provided with a plurality of rotation units that change the positions and attitudes of the head and the energy output unit relative to the base, Among the plurality of rotation units, a rotation unit that rotates the largest amount during execution of the second operation is designated as a first rotation unit; a second rotation unit that rotates the first operation of the plurality of rotation units closer to the base than the first rotation unit; a rotation amount of the first rotation unit during execution of the first operation is defined as R11; a rotation amount of the second rotation unit during execution of the first operation is defined as R12; a rotation amount of the first rotation unit during execution of the second operation is defined as R21; When the rotation amount of the second rotation unit during the execution of the second operation is R22, The relationship R21 / R22>R11 / R12 is satisfied. A three-dimensional object printing method.

19. a head having a discharge surface provided with nozzles for discharging liquid; an energy emission unit having an emission surface that emits energy to harden or solidify the liquid ejected from the head; a movement mechanism that is a robot having a base and an arm supported on the base, the robot supporting the head and the energy output unit at a tip of the arm, and that changes the relative positions and attitudes of the head and the energy output unit with respect to a three-dimensional workpiece; a first operation that simultaneously executes the discharge of liquid onto the workpiece by the head, the emission of energy onto the workpiece by the energy emission unit, and the relative movement of the head and the energy emission unit with respect to the workpiece by the movement mechanism; performing a second operation subsequent to the first operation, in which the energy output unit outputs energy to the workpiece, and the movement mechanism moves the head and the energy output unit relative to the workpiece, without discharging liquid from the head to the workpiece; a first irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the first operation, and a second irradiation distance, which is a distance between the workpiece and the emission surface along a normal direction of the emission surface during execution of the second operation, are different from each other; A three-dimensional object printing device characterized by the above.

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