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

Abstract

To provide a three-dimensional object printer which makes prints on three-dimensional workpieces by ink jet printing while reducing clogging of nozzles.SOLUTION: A three-dimensional object printer has: a head having a nozzle surface provided with multiple nozzles which discharge a liquid; a robot which has a base part and an arm part which supports the head, is provided with multiple rotation parts located from the base part to the arm part, and changes a position of the head relative to the base part by rotation of the rotation parts; and a cap part whose position is fixed relative to the base part and which covers the nozzle surface. The three-dimensional object printer conducts cap operation in which the robot places the head to a position where the nozzle surface is covered with the cap part and print operation in which the head discharges the liquid to a workpiece while the robot changes a position of the head relative to the workpiece at a position which is different from the position where the head is located when the cap operation is conducted. A yaw-angle of the head formed when the cap operation is conducted is different from a yaw-angle of the head formed when the print operation is conducted.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There is known a three-dimensional printing device that performs printing on the surface of a three-dimensional workpiece by an inkjet method. For example, the device described in Patent Document 1 has a robot arm and a print head fixed to the tip of the robot arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-050832 A Summary of the Invention [Problem to be solved by the invention]

[0004] The printing device described in Patent Document 1 has a problem in that the ink near the nozzles of the print head becomes viscous or solidifies due to the effects of external light or drying caused by the outside air, causing the nozzles to become clogged, resulting in poor ejection. [Means for solving the problem]

[0005] In order to solve the above problems, one aspect of the three-dimensional printing device of the present invention has a head having a nozzle surface with a plurality of nozzles for ejecting liquid, a base, and an arm portion supporting the head, with a plurality of rotating portions provided from the base to the arm portion, a robot that changes the position of the head relative to the base by rotating the rotating portions, and a cap portion that covers the nozzle surface, and performs a capping operation in which the robot positions the head in a position where the nozzle surface is covered by the capping portion, and a printing operation in which the head ejects liquid onto the workpiece while the robot changes the position of the head relative to the workpiece to a position different from that during the capping operation, and the yaw angle of the head during the capping operation and the yaw angle of the head during the printing operation are different from each other.

[0006] One aspect of the three-dimensional object printing method according to the present invention is a three-dimensional object printing method using a robot having a head having a nozzle surface with a plurality of nozzles for ejecting liquid, a base, and an arm portion supporting the head, with a plurality of rotating portions extending from the base to the arm portion, the position of the head relative to the base being changed by rotating the rotating portion, and a cap portion covering the nozzle surface, wherein the method performs a capping operation in which the robot positions the head at a position where the nozzle surface is covered by the capping portion, and a printing operation in which the head ejects liquid onto the workpiece while the robot changes the position of the head relative to the workpiece to a position different from that during the capping operation, and the yaw angle of the head during the capping operation and the yaw angle of the head during the printing operation are different from each other. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view showing an outline of a three-dimensional object printing device according to an embodiment. FIG. [Diagram 2] FIG. 2 is a block diagram showing the electrical configuration of the three-dimensional object printing device according to the embodiment. [Diagram 3] FIG. 2 is a perspective view showing a schematic configuration of a head unit including a head. [Figure 4] FIG. 2 is a perspective view showing a schematic configuration of a maintenance unit including a cap portion. [Diagram 5] 4 is a flowchart showing the operation of the three-dimensional object printing device according to the embodiment. [Figure 6] FIG. 2 is a side view of the robot during a printing operation. [Figure 7] FIG. 2 is a plan view of the three-dimensional object printing device during a printing operation. [Figure 8] FIG. 2 is a plan view of the three-dimensional object printing device during a capture operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, preferred embodiments of the present invention will be described 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 some parts are shown diagrammatically to facilitate understanding. Furthermore, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited thereto.

[0009] For convenience, the following description will be made using 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 to the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. In addition, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction.

[0010] 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 below is installed. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. A base coordinate system based on the base of the robot 2 is associated with the world coordinate system by calibration. For convenience, the following will exemplify a case in which the operation of the robot 2 is controlled using the world coordinate system as the robot coordinate system.

[0011] The Z axis does not have to be a vertical axis. The X axis, the Y axis, and the Z axis are typically mutually orthogonal, but are not limited thereto, and may not be orthogonal. For example, the X axis, the Y axis, and the Z axis may intersect each other at an angle within a range of 80° to 100°.

[0012] 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 an embodiment of the present invention. 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.

[0013] The workpiece W has a surface WF to be printed. In the example shown in FIG. 1, the workpiece W is a rugby ball having an oblong shape, and the surface WF is a curved surface. The workpiece W during printing is supported by a structure such as a predetermined installation table, a robot hand, or a conveyor, as necessary. The shape, size, and other aspects of the workpiece W or the surface WF are not limited to the example shown in FIG. 1 and are arbitrary. In addition, 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.

[0014] 1, the three-dimensional object printing apparatus 1 has a robot 2, a head unit 3, a maintenance unit 4, a controller 5, a piping section 10, and a wiring section 11. First, each of these will be briefly described in order below.

[0015] The robot 2 is a robot that changes the position and orientation 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.

[0016] As shown in FIG. 1, the robot 2 has a base 210 and an arm 220.

[0017] The base 210 is a platform that supports the arm 220. In the example shown in FIG. 1, the base 210 is fixed to an installation surface such as a floor surface or a base facing the Z1 direction by screwing or the like. The installation surface to which the 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 dolly, or the like. In the following, a view in a direction perpendicular to the installation surface of the base 210, that is, a view in the Z1 direction or Z2 direction in this embodiment, may be referred to as a "planar view of the base 210" or simply a "planar view".

[0018] Arm 220 is a six-axis robot arm having a base end attached to base 210 and a tip end that changes its position and posture three-dimensionally relative to the base end. Specifically, arm 220 has arms 221, 222, 223, 224, 225, and 226, which are connected in this order.

[0019] 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.

[0020] Each of the joints 230_1 to 230_6 is an example of a "rotating part" 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. Here, the joint 230_1, which is closest to the base 210 among the joints 230_1 to 230_6, is an example of a "first rotating part." Furthermore, the joint 230_6, which is farthest from the base 210 among the joints 230_1 to 230_6, is an example of a "second rotating part." Note that, hereinafter, each of the joints 230_1 to 230_6 may be referred to as a "joint 230."

[0021] Although not shown in Fig. 1, each of the joints 230_1 to 230_6 is provided with a drive mechanism for rotating 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 the speed of the drive force and outputs it, and an encoder such as a rotary encoder that detects an amount of movement such as an 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 described later.

[0022] 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.

[0023] With regard to 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 offset within a range of about ±5° from 90°. Similarly, "parallel" refers not only to the case where the two rotation axes are exactly parallel, but also to the case where one of the two rotation axes is inclined relative to the other axis within a range of about ±5°.

[0024] A head unit 3 is attached as an end effector to the arm 226 located at the very tip of the arm section 220 of the robot 2 as described above, in a state fixed thereto by screws or the like.

[0025] 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, a curing light source 3c, and a distance sensor 3d in addition to the head 3a. Details of the head unit 3 will be described later with reference to FIG. 3.

[0026] 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 a water-based solvent, curable inks using a curable resin such as an ultraviolet curable type, and solvent-based inks in which a coloring material such as a dye or pigment is dissolved in an organic solvent. Among them, curable inks are preferably used. The curable ink is not particularly limited, and may be, for example, any of a heat curable type, a photocurable type, a radiation curable type, and an electron beam curable type, but a photocurable type such as an ultraviolet curable type is preferable. The ink is not limited to a solution, and may be an ink in which a coloring material or the like is dispersed as a dispersoid in a dispersion medium. The ink is not limited to an ink containing a coloring material, and may be, for example, an ink containing conductive particles such as metal particles for forming wiring or the like as a dispersoid, a clear ink, or a treatment liquid for surface treatment of the workpiece W.

[0027] The head unit 3 is connected to a piping section 10 and a wiring section 11. The piping section 10 is a piping or a group of piping including a supply pipe 10a that supplies ink from an ink tank (not shown) to the head unit 3. The supply pipe 10a is a flexible tube made of, for example, a rubber material or an elastomer material. The wiring section 11 is a wiring or a group of wiring including a drive wiring 11a that supplies an electric signal that drives the head 3a. The drive wiring 11a is made of, for example, various flexible electric wiring. In addition to the supply pipe 10a, the piping section 10 may include other piping such as a pipe for transporting ink discharged from the head unit 3. In addition to the drive wiring 11a, the wiring section 11 appropriately includes various wirings for transmitting other electronic signals such as a control signal SI, which will be described later, that are necessary for driving the head 3a.

[0028] Each of the piping section 10 and the wiring section 11 is fixed to the head unit 3 at a fixing position FX1 by connection with the head unit 3. The fixing position FX1 is a position in the end effector, and specifically, is a position of a connector (not shown) for connecting the piping section 10 and the wiring section 11 to the head unit 3. Also, each of the piping section 10 and the wiring section 11 is fixed to the arm section 220 of the robot 2 described above at fixing positions FX2, FX3, and FX4 by a cable tie or the like. The fixing position FX2 is a position on the arm 224 described above. The fixing position FX3 is a position on the arm 223 described above. The fixing position FX4 is a position on the arm 222 described above. By fixing the piping section 10 and the wiring section 11 partially to a plurality of positions on the arm section 220 in this manner, it is possible to maintain the positional relationship between the arm section 220 and the piping section 10 and the wiring section 11 within a predetermined range while fully allowing the movement of the arm section 220. In addition, in FIG. 1, a configuration in which the piping section 10 and the wiring section 11 are routed along the same route is illustrated, but the routes along which the piping section 10 and the wiring section 11 are routed may differ from each other in some parts.

[0029] The maintenance unit 4 is a mechanism for performing maintenance on the head 3a of the head unit 3. In the example shown in FIG. 1, the maintenance unit 4 has a case 4a, a cap portion 4b, a support base 4c, a suction mechanism 4d, and a wiper portion 4e. The case 4a is fixed to an installation surface such as a floor surface or a base facing the Z1 direction by screwing, as with the base portion 210 of the robot 2. Details of the maintenance unit 4 will be described later with reference to FIG. 3. The term "maintenance" refers to a concept that includes covering the nozzle surface F of the head 3a with the cap portion 4b, suctioning with the suction mechanism 4d, wiping with the wiper portion 4e, and the like.

[0030] 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.

[0031] 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 device 1 according to the embodiment. Fig. 2 shows electrical components among the components of the three-dimensional object printing device 1. As shown in Fig. 2, in addition to the components shown in Fig. 1 described above, the three-dimensional object printing device 1 has a control module 6 communicatively connected to the controller 5, and a computer 7 communicatively connected to the controller 5 and the control module 6. Before describing the controller 5 in detail, the control module 6 and the computer 7 will first be described in order.

[0032] 2 may be appropriately divided, some of the components may be included in other components, or the components may be integrated with other components. For example, some or all of the functions of the controller 5 or the control module 6 may be implemented by a computer 7, or may be implemented by another external device such as a personal computer (PC) connected to the controller 5 via a network such as a local area network (LAN) or the Internet.

[0033] 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. Note that the controller 5 of this embodiment also has a function of controlling the driving of the maintenance unit 4, but this function may be realized by other devices such as a computer 7.

[0034] The controller 5 includes a memory circuit 5a and a processing circuit 5b.

[0035] 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 one or both of semiconductor memories, for example, a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM) or a programmable ROM (PROM). Note that a part or the whole of the storage circuit 5a may be included in the processing circuit 5b.

[0036] The path information Da is stored in the memory circuit 5a. The path information Da is information indicating the path along which the head unit 3 should move and the attitude of the head unit 3 on the path. Here, the path information Da includes, as information indicating the path and attitude, information indicating the movement path and attitude of the head unit 3 when printing on the workpiece W, and information indicating the movement path and attitude between the position of the head unit 3 during printing and the position during maintenance by the maintenance unit 4. The path information Da is determined, for example, based on the shape of the workpiece W, and is expressed using coordinate values ​​of a base coordinate system or a world coordinate system. The shape of the workpiece W is obtained, for example, from CAD (computer-aided design) data indicating the three-dimensional shape of the workpiece W. The above path information Da is input from the computer 7 to the memory circuit 5a.

[0037] The processing circuit 5b controls the operation of the arm driving mechanism 2a of the robot 2 based on the path information Da, and generates a signal D3. The processing circuit 5b includes, for example, a processor such as one or more CPUs (Central Processing Units). 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.

[0038] Here, the arm driving mechanism 2a is an assembly of driving mechanisms for the above-mentioned 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.

[0039] The processing circuit 5b performs inverse kinematic calculation, which is a calculation to convert the path information Da into movement amounts such as the rotation angle and rotation speed of each joint of the robot 2. Then, the processing circuit 5b outputs a control signal Sk1 based on the output D1 from each encoder of the arm driving mechanism 2a so that the movement amounts such as the actual rotation angle and rotation speed of each joint become the above-mentioned calculation results based on the path information Da. The control signal Sk1 controls the driving of the motor of the arm driving mechanism 2a. Here, the control signal Sk1 is corrected by the processing circuit 5b based on the output from the distance sensor 3d as necessary.

[0040] 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 driving mechanism 2a. For example, the processing circuit 5b generates, as the signal D3, a trigger signal including a pulse at a timing when the output D1 from one of the multiple encoders becomes a predetermined value.

[0041] The control module 6 is a circuit that controls the ink ejection operation of the head unit 3 based on a 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.

[0042] The timing signal generating circuit 6a generates a timing signal PTS based on the signal D3. The timing signal generating circuit 6a is formed of, for example, a timer that starts generating the timing signal PTS in response to detection of the signal D3.

[0043] The power supply circuit 6b receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are appropriately supplied to the control module 6 and each part 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.

[0044] 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.

[0045] The control signal SI is a digital signal for specifying the operating state of the drive element of the head 3a of the head unit 3. Specifically, the control signal SI specifies whether or not to supply the drive signal Com described below to the drive element. This specification, for example, specifies whether or not to eject ink from the nozzle corresponding to the drive element, and specifies the amount of ink ejected from the nozzle. The waveform specification signal dCom is a digital signal for defining the waveform of the drive signal Com. The latch signal LAT and the change signal CNG are used in conjunction with the control signal SI to specify the drive timing of the drive element, thereby specifying the ejection timing of ink from the nozzle. The clock signal CLK is a reference clock signal synchronized with the timing signal PTS.

[0046] The control circuit 6c includes, for example, one or more processors such as a CPU (Central Processing Unit). 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.

[0047] The drive signal generating 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 generating circuit 6d has, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generating 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, among the waveforms included in the drive signal Com, a signal of a waveform that is actually supplied to the drive element is a drive pulse PD. The drive pulse PD is supplied from the drive signal generating circuit 6d to the drive element via the switch circuit 3e of the head unit 3.

[0048] Here, the switch circuit 3e is a circuit that switches whether or not at least a part of the waveform included in the drive signal Com is supplied as the drive pulse PD, based on a control signal SI.

[0049] The computer 7 has a function of supplying information such as path information Da to the controller 5, and a function of supplying information such as print data to the control module 6. The computer 7 is, for example, a desktop or notebook computer on which a program for realizing these functions is installed.

[0050] 1-3.Head unit configuration 3 is a perspective view showing a schematic configuration of the head unit 3 including the head 3a. In the following description, for convenience, the mutually intersecting a-axis, b-axis, and c-axis are appropriately used. In the following description, one direction along the a-axis is the a1 direction, and the direction opposite to the a1 direction is the a2 direction. Similarly, the opposite directions along the b-axis are the b1 direction and the b2 direction. In addition, the opposite directions along the c-axis are the c1 direction and the c2 direction.

[0051] Here, the a-axis, the b-axis, and the 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 the robot coordinate system changes due to the operation of the robot 2 described above. In the example shown in FIG. 3, the c-axis is an axis parallel to the rotation axis O6 described above. The a-axis, the b-axis, and the c-axis are typically mutually orthogonal, but are not limited thereto, and may intersect at an angle within a range of 80° to 100°, for example. The tool coordinate system and the base coordinate system or the robot coordinate system are associated with each other by calibration. The tool coordinate system is set, for example, so that the center of the nozzle surface F described later is the reference (tool center point).

[0052] As described above, the head unit 3 has the head 3a, the pressure regulating valve 3b, the curing light source 3c, and the distance sensor 3d. 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 regulating valve 3b, but the number is not limited to the example shown in FIG. 3 and may be two or more. In addition, the installation position of the pressure regulating valve 3b is not limited to the arm 226 and may be, for example, another arm or the like, or may be a fixed position relative to the base 210.

[0053] The support 3f is made of, for example, a metal material, and is substantially rigid. Although the support 3f has a flat box shape in Fig. 3, the shape of the support 3f is not particularly limited and may be any shape.

[0054] The support 3f is attached to the arm 226 described above. Therefore, the head 3a, the pressure regulating valve 3b, the curing light source 3c, and the distance sensor 3d are collectively supported on the arm 226 by the support 3f. Therefore, the relative positions of the head 3a, the pressure regulating valve 3b, the curing light source 3c, and the distance sensor 3d with respect to the arm 226 are fixed. In the example shown in FIG. 3, the pressure regulating valve 3b is disposed at a position in the c1 direction with respect to the head 3a. The curing light source 3c is disposed at a position in the a2 direction with respect to the head 3a. The distance sensor 3d is disposed at a position in the a1 direction with respect to the head 3a.

[0055] The head 3a has a nozzle surface F and a plurality of nozzles N opening on the nozzle surface F. In the example shown in FIG. 3, the normal direction of the nozzle surface F is the c2 direction, and the plurality of nozzles N are divided into nozzle rows La and nozzle rows Lb arranged at intervals in the direction along the a-axis. Each of the nozzle rows La and nozzle rows Lb is a collection of a plurality of nozzles N linearly arranged in the direction along the b-axis. Here, elements related to each nozzle N of the nozzle row La in the head 3a and elements related to each nozzle N of the nozzle row Lb are configured to be approximately symmetrical to each other in the direction along the a-axis. In addition, a nozzle row direction DN, which will be described later, is parallel to the b-axis.

[0056] In this embodiment, the nozzle surface F is a concept including both the surface formed by the nozzle plate and the surface formed by the fixed plate and the cover head. The nozzle plate is a plate-like member made of silicon (Si) or metal, in which the nozzles N are opened, and the fixed plate and the cover head are members provided around the nozzle plate for the purpose of fixing and protecting the nozzle plate. The fixed plate and the cover head may not be provided depending on the configuration of the head, and the nozzle surface F shown in FIG. 3 is formed only by the nozzle plate.

[0057] However, the positions of the multiple nozzles N in the nozzle row La and the multiple nozzles N in the nozzle row Lb in the direction along the b-axis may be the same or different. Also, elements related to each nozzle N of one of the nozzle row La and the nozzle row Lb may be omitted. In the following, a configuration in which the positions of the multiple nozzles N in the nozzle row La and the multiple nozzles N in the nozzle row Lb in the direction along the b-axis are the same will be exemplified.

[0058] Although not shown, the head 3a has a piezoelectric element as a drive element and a cavity that contains 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 is obtained, for example, by bonding together, with an adhesive, a plurality of 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 a drive element for ejecting ink from the nozzle.

[0059] As described above, ink is supplied from an ink tank (not shown) to the head 3a via the supply pipe 10a. A pressure adjustment valve 3b is interposed between the supply pipe 10a and the head 3a.

[0060] The pressure regulating valve 3b is a valve mechanism that opens and closes according to the pressure of the ink in the head 3a. This opening and closing maintains the pressure of the ink in 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 meniscus of the ink 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. In addition, the ink from the pressure regulating valve 3b is appropriately distributed to multiple locations in the head 3a via branch channels (not shown). Here, the ink from the ink tank (not shown) is transferred into the supply pipe 10a at a predetermined pressure by a pump or the like.

[0061] The curing light source 3c emits energy such as light, heat, electron beams, or radiation to cure or solidify the ink on the workpiece W. For example, if the ink is ultraviolet curable, the curing light source 3c is composed of a light emitting element such as an LED (light emitting diode) that emits ultraviolet light. The curing light source 3c may also have optical components such as lenses for adjusting the emission direction or emission range of the energy as appropriate.

[0062] It should be noted that the curing light source 3c does not have to completely cure or completely solidify the ink on the workpiece W. In this case, for example, the ink after being irradiated with energy from the curing light source 3c may be completely cured or completely solidified by energy from a curing light source separately installed on the installation surface of the base 210 of the robot 2. Also, the curing light source 3c may be provided as necessary, and may be omitted.

[0063] The distance sensor 3d is an optical displacement sensor that measures the distance between the head 3a and the workpiece W. The distance sensor 3d in this embodiment outputs a signal according to the distance between the head 3a and the workpiece W in the direction along the c-axis. Note that the distance sensor 3d may be provided as necessary, and may be omitted.

[0064] 1-4. Maintenance unit configuration Fig. 4 is a perspective view showing a schematic configuration of the maintenance unit 4 including the cap portion 4b. As described above, the maintenance unit 4 shown in Fig. 4 has the case 4a, the cap portion 4b, the support base 4c, the suction mechanism 4d, and the wiper portion 4e.

[0065] The case 4a is a box-shaped structure that supports the cap portion 4b, the support base 4c, the suction mechanism 4d, and the wiper portion 4e. The shape of the case 4a is not limited to the example shown in FIG.

[0066] The cap part 4b is a structure having a cap 4b1 that covers the nozzle surface F of the head 3a, a guide part 4b2, and a biasing mechanism 4b3. In the example shown in FIG. 4, the cap part 4b has a longitudinal shape. The cap 4b1 is an elastic cover body made of a rubber material, an elastomer material, or the like, and covers the nozzle surface F of the head 3a to prevent the ink near the nozzles N of the head 3a from drying. The cap 4b1 is provided with an outer frame part that abuts against the nozzle surface F of the head 3a, a bottom surface that is recessed in the Z2 direction relative to the outer frame part, and a hole that penetrates the cap 4b1. In a capping operation to be described later in which the nozzle surface F of the head 3a is covered by the cap part 4b, the outer frame part abuts against the nozzle surface F of the head 3a so as to surround the nozzles N provided on the nozzle surface F in a horizontal state. At this time, the bottom surface faces the nozzle surface F. The hole has one end opening that opens to the bottom surface of the recess, and the other end opening that is connected to the suction mechanism 4d.

[0067] The biasing mechanism 4b3 is a mechanism that supports the cap 4b1 and biases it in the Z1 direction, and is composed of an elastic body such as a spring or rubber. The guide portion is a member that restricts the movement of the cap 4b1 in a direction different from the Z direction. When the nozzle surface F of the head 3a and the aforementioned outer frame portion abut against each other, the elastic body of the biasing mechanism 4b3 elastically deforms so as to contract in the Z direction. The biasing mechanism 4b3 may be a mechanism such as a gas stay.

[0068] The cap portion 4b is supported by a support base 4c. The support base 4c is composed of a top surface portion 4c1 to which the cap portion 4b is fixed, and a plurality of legs 4c2 that support the top surface portion 4c1. The top surface portion 4c1 is a plate-shaped member made of a metal material or the like, and the cap portion 4b and the wiper portion 4e are fixed to the top surface portion 4c1 by screws or the like.

[0069] The suction mechanism 4d is a mechanism for reducing the pressure in the space formed between the cap portion 4b and the nozzle surface F. By reducing the pressure, ink is sucked from the nozzles N of the head 3a with the nozzle surface F covered by the cap portion 4b, thereby refreshing the ink in the nozzles N. The suction mechanism 4d has a pressure reduction tank and a pressure reduction pump 4d2, not shown. The pressure reduction tank is, for example, a metal chamber having an internal space to be reduced in pressure, and is disposed in the above-mentioned case 4a. The pressure reduction tank communicates with the hole of the above-mentioned cap portion 4b and also communicates with the pressure reduction pump. The pressure reduction pump is a mechanism for reducing the pressure in the pressure reduction tank by discharging air from the pressure reduction tank. Valves for adjusting pressure or opening and closing are provided between the pressure reduction tank and the cap portion 4b, and between the pressure reduction tank and the pressure reduction pump.

[0070] The wiper portion 4e is disposed adjacent to the cap portion 4b, and is a structure having a wiper 4e1 that wipes the nozzle surface F. In the example shown in FIG. 4, the wiper portion 4e has an elongated shape and is disposed parallel to the cap portion 4b. The wiper 4e1 is an elastic blade-like member made of a rubber material, an elastomer material, or the like, and cleans the nozzle surface F of the head 3a by wiping the nozzle surface F. The wiper 4e1 is fixed onto the top surface portion 4c1 of the support base 4c via a support 4e2 by means of screws or the like.

[0071] 1-5. Operation of the three-dimensional object printing device 1 Fig. 5 is a flowchart showing the operation of the three-dimensional object printing device 1 according to the embodiment. As shown in Fig. 5, the three-dimensional object printing device 1 first determines whether or not there is a print instruction in step S1. This determination is made, for example, by the processing circuit 5b determining whether or not there is a print execution instruction from the computer 7.

[0072] When a print command is issued, the three-dimensional object printing apparatus 1 performs a first movement operation in step S2. This first movement operation is an operation for moving the head 3a to a position for starting execution of a printing operation described below, and is performed by the processing circuit 5b controlling the driving of the robot 2 based on the path information Da.

[0073] After step S2, the three-dimensional object printing apparatus 1 performs a printing operation in step S3. This printing operation is an operation of printing on the workpiece W with ink from the head 3a, and is performed by the processing circuit 5b controlling the driving of the robot 2 based on the path information Da, and the control module 6 controlling the driving of the head 3a.

[0074] After step S3, or if there is no print instruction, the three-dimensional object printing apparatus 1 determines in step S4 whether or not there is a cap instruction. This determination is made, for example, by the processing circuit 5b determining whether or not there is a cap instruction from the computer 7. Note that the processing circuit 5b may determine that there is a cap instruction if there is no print instruction or cap instruction from the computer 7 for a predetermined period of time or more.

[0075] If there is no capping command, the three-dimensional object printing apparatus 1 returns to step S1 described above. On the other hand, if there is a capping command, the three-dimensional object printing apparatus 1 performs a second movement operation in step S5. This second movement operation is an operation of moving the head 3a to a start position for the execution of a capping operation described later, and is performed by the processing circuit 5b controlling the driving of the robot 2 based on the path information Da.

[0076] After step S5, the three-dimensional object printing apparatus 1 performs a capping operation in step S6. This capping operation is, for example, an operation in which the nozzle surface F of the head 3a comes into contact with the cap portion 4b, thereby covering the nozzle surface F with the cap portion, and is performed by the processing circuit 5b controlling the driving of the robot 2 based on the path information Da. Note that the capping operation may also include an operation in which the nozzle surface F does not come into contact with the cap portion 4b strictly speaking. For example, this applies when the nozzle surface F and the cap portion 4b are spaced apart by several millimeters, or when ink or the like is interposed between the nozzle surface F and the cap portion 4b.

[0077] After step S6, in step S7, the three-dimensional object printing apparatus 1 determines whether or not there is an end instruction. This determination is made, for example, by the processing circuit 5b determining whether or not there is an end instruction from the computer .

[0078] If there is no end instruction, the three-dimensional object printing apparatus 1 returns to step S1 described above, whereas if there is an end instruction, the operation ends.

[0079] Fig. 6 is a side view of the robot 2 during the printing operation of step S3. Fig. 6 illustrates a case where printing is performed on a surface WF of a prolate spheroidal workpiece W arranged so that the major axis AX of the workpiece W is parallel to the X axis. Here, the workpiece W is placed at a position in the X2 direction further from the robot 2. In addition, in the attitude of the head 3a shown by the solid line in Fig. 6, the a-axis is parallel to the X axis, the b-axis is parallel to the Y axis, and the c-axis is parallel to the Z axis.

[0080] In the printing operation, the robot 2 moves the head 3a along a movement path RU, as shown in Fig. 6. The movement path RU is a path along the surface WF from the position PS to the position PE. The movement path RU forms a straight line extending along the X-axis when viewed in the Z2 direction.

[0081] In the printing operation, the robot 2 operates three of the six joints 230. In the example shown in Fig. 6, the robot 2 operates the joints 230_2, 230_3, and 230_5 while the printing operation is being performed, with the rotation axes of these joints 230_2, 230_3, and 230_5 being parallel to the Y axis. In this manner, the head 3a can be stably moved along the movement route RU by the operation of the three joints 230.

[0082] Here, it is preferable that the robot 2 controls the attitude of the head 3a according to the curved surface of the surface WF so that the landing direction of the ink from the head 3a on the surface WF is constant. For this reason, it is preferable that the yaw angle and roll angle of the head 3a on the movement path RU are constant. On the other hand, it is preferable that the pitch angle of the head 3a on the movement path RU varies. That is, it is preferable that the pitch angles of the head 3a at the first position P1 and the second position P2, which are two arbitrary points on the movement path RU, are different from each other. In this embodiment, the movement path RU is set so that the ejection direction vector of the ink droplets ejected by the head 3a always includes a vertical downward component. In other words, the vector in the c2 direction includes a component in the Z2 direction. According to such a setting of the movement path RU, the head 3a does not eject ink droplets in a direction against gravity, so that the flight of the ink droplets is stable.

[0083] Printing is performed on the workpiece W through the above printing operations.

[0084] Here, the yaw angle, roll angle, and pitch angle of the head will be explained. The yaw angle, roll angle, and pitch angle of the head 3a are expressed as the amount of rotation about the c-axis, a-axis, and b-axis with respect to a reference posture of the head 3a that is arbitrarily set. Note that in the reference posture of the head 3a, the relationship between the a-axis, b-axis, and c-axis and the X-axis, Y-axis, and Z-axis is uniquely fixed.

[0085] The yaw angle of the head 3a in the first posture is expressed as the amount of rotation about the c-axis required for a posture change from the reference posture to the first posture. This amount of rotation about the c-axis is the absolute value of the angle between the a-axis in the reference posture and the a-axis in the first posture when viewed in a direction along the c-axis in the reference posture. Alternatively, the amount of rotation about the c-axis is the absolute value of the angle between the b-axis in the reference posture and the b-axis in the first posture when viewed in a direction along the c-axis in the reference posture.

[0086] Similarly, the roll angle of the head 3a in the first posture is expressed as the amount of rotation around the a-axis required for a posture change from the reference posture to the first posture. This amount of rotation around the a-axis is the absolute value of the angle between the b-axis in the reference posture and the b-axis in the first posture when viewed in a direction along the a-axis in the reference posture. Alternatively, the amount of rotation around the a-axis is the absolute value of the angle between the c-axis in the reference posture and the c-axis in the first posture when viewed in a direction along the a-axis in the reference posture.

[0087] Similarly, the pitch angle of the head 3a in the first posture is expressed as the amount of rotation about the b-axis required for a posture change from the reference posture to the first posture. This amount of rotation about the b-axis is the absolute value of the angle between the a-axis in the reference posture and the a-axis in the first posture when viewed in a direction along the b-axis in the reference posture. Alternatively, the amount of rotation about the b-axis is the absolute value of the angle between the c-axis in the reference posture and the c-axis in the first posture when viewed in a direction along the b-axis in the reference posture.

[0088] The yaw angle, roll angle, and pitch angle of the head 3a will be further described with reference to FIG. 6. For example, the reference posture of the head 3a is set as a posture in which the a-axis is parallel to the X-axis, the b-axis is parallel to the Y-axis, and the c-axis is parallel to the Z-axis. At this time, the yaw angle, roll angle, and pitch angle of the head 3a shown by the solid line in FIG. 6 are all 0°. On the other hand, the pitch angle of the head 3a shown by the dashed line in FIG. 6 is about 45°, and the yaw angle and roll angle are 0°. In other words, the pitch angles of the head 3a shown by the solid line in FIG. 6 and the head 3a shown by the dashed line are different from each other.

[0089] FIG. 7 is a plan view of the three-dimensional object printing device 1 during the execution of the printing operation. In the posture of the head 3a shown by the solid line in FIG. 7, the a-axis and the X-axis are parallel, the b-axis and the Y-axis are parallel, and the c-axis and the Z-axis are parallel. During the execution of the printing operation, as shown in FIG. 7, in a plan view of the base 210, the nozzle row direction DN, which is the arrangement direction of the multiple nozzles N of the head 3a, is perpendicular to the scanning direction DS of the head 3a on the above-mentioned movement path RU. Here, when a virtual line segment connecting the head 3a and the base 210 during the execution of the printing operation in a plan view of the base 210 is set as a first line segment L1, the angle θ1 between the nozzle row direction DN and the first line segment L1 is 90°. However, the angle θ1 is not limited to 90°, and may be within a range of, for example, 70° to 110°. The first line segment L1 can also be more precisely defined as an imaginary line segment that connects the center point of the nozzle surface F and the rotation axis O1 during a printing operation in a plan view of the base portion 210.

[0090] After the printing operation is performed, the head 3a moves onto the cap portion 4b by the second movement operation described above, as shown by the two-dot chain line in Fig. 7. In the position of the head 3a shown by the two-dot chain line in Fig. 7, the c-axis and the Z-axis are parallel, but the angle between the a-axis and the X-axis is 45°, and the angle between the b-axis and the Y-axis is 45°.

[0091] Here, the reference posture of the head 3a is set as a posture in which the a-axis and the X-axis are parallel, the b-axis and the Y-axis are parallel, and the c-axis and the Z-axis are parallel. At this time, the yaw angle, roll angle, and pitch angle of the head 3a shown by the solid line in FIG. 7 are all 0°. On the other hand, the yaw angle of the head 3a shown by the two-dot chain line in FIG. 7 is 45°, and the roll angle and pitch angle are 0°. That is, the yaw angles of the head 3a shown by the solid line in FIG. 7 and the head 3a shown by the two-dot chain line are different from each other. In other words, the nozzle row direction DN of the nozzle N as viewed in the Z1 direction from an arbitrary coordinate in the world coordinate system is different from each other during the execution of the printing operation and after the execution of the moving operation or during the execution of the capping operation. More specifically, the angle between the nozzle row direction DN during the execution of the printing operation and the nozzle row direction DN after the execution of the moving operation or during the execution of the capping operation is 45°.

[0092] The second movement operation is mainly performed by operating the joint 230_1. Here, the joints 230_2, 230_3, and 230_5 used in the above-mentioned printing operation may be operated, but it is preferable not to operate the joints 230_4 and 230_6. In this case, when the printing operation is performed again, the reproducibility of the operation of the robot 2 in the printing operation can be improved.

[0093] 8 is a plan view of the three-dimensional object printing device 1 during the execution of the capping operation. As shown in FIG. 8, when the virtual line segment connecting the head 3a and the base 210 during the execution of the capping operation in the plan view of the base 210 is the second line segment L2, the angle θ2 between the nozzle row direction DN and the second line segment L2 is 90°. However, the angle θ2 is not limited to 90°, and may be within a range of, for example, 70° to 110°. The second line segment L2 can also be more strictly defined as a virtual line segment connecting the center point of the nozzle surface F and the rotation axis O1 during the execution of the capping operation in the plan view of the base 210.

[0094] Here, when the angle between the first line segment L1 and the second line segment L2 in a plan view of the base portion 210 is θ3, the angles θ1, θ2, and θ3 satisfy the relationship |θ1-θ2|<θ3. From the viewpoint of reducing twisting of the piping portion 10 and the wiring portion 11, it is preferable that |θ1-θ2| is as small as possible.

[0095] After the capping operation is performed, the head 3a is moved to the printing position by the first movement operation described above, as shown by the two-dot chain line in Fig. 8. The first movement operation is performed mainly by moving the joint portion 230_1, similar to the second movement operation.

[0096] As described above, the three-dimensional object printing device 1 has the head 3a, the robot 2, and the cap unit 4b. The head 3a has a nozzle surface F provided with a plurality of nozzles N that eject ink, which is an example of a "liquid." The robot 2 has a base 210 and an arm 220 that supports the head 3a, and joints 230_2 to 230_6, which are an example of a "plurality of rotating parts," are provided from the base 210 to the arm 220, and the position of the head 3a relative to the base 210 is changed by the rotation of the joints 230_2 to 230_6. The cap unit 4b covers the nozzle surface F.

[0097] Then, the three-dimensional object printing apparatus 1 executes the capping operation of step S6 and the printing operation of step S3 as described above. In the capping operation of step S6, the robot 2 positions the head 3a at a position where the nozzle surface F is covered by the cap portion 4b. In the printing operation of step S3, the head 3a ejects ink onto the workpiece W while the robot 2 changes the position of the head 3a relative to the workpiece W to a position different from that during the capping operation of step S6. Here, the yaw angle of the head 3a during the capping operation of step S6 and the yaw angle of the head 3a during the printing operation of step S3 are different from each other.

[0098] In the above three-dimensional object printing device 1, since the nozzle surface F is covered by the capping portion 4b during the capping operation in step S6, thickening or solidification of the ink on the nozzle surface F can be reduced even if the printing operation in step S3 is not performed for a long period of time. As a result, clogging of each nozzle N by ink can be reduced. In addition, by making the yaw angle of the head 3a different during the capping operation in step S6 and during the printing operation in step S3, the amount of rotation of the joint 230_6, which is the closest to the head among the multiple joints 230 of the robot 2, can be reduced when moving the head 3a between the positions where these operations are performed. As a result, damage caused by twisting of wiring related to the head 3a can be reduced.

[0099] Here, the three-dimensional printing device 1 further includes a supply tube 10a that supplies ink to the head 3a, and a drive wiring 11a that supplies an electric signal for driving the head 3a to the head 3a. The supply tube 10a and the drive wiring 11a are provided outside the arm 220. Such supply tube 10a and drive wiring 11a may be damaged by twisting if the printing operation of step S3 and the capping operation of step S6 are repeatedly performed while maintaining the yaw angle of the head 3a constant. Therefore, when such supply tube 10a or drive wiring 11a is used, the above-mentioned effect of making the yaw angle of the head 3a different between the printing operation of step S3 and the capping operation of step S6 becomes prominent.

[0100] In addition, from the viewpoint of reducing damage caused by twisting of wiring, as described above, when the angle between the first line segment L1 and the nozzle row direction DN during the execution of the printing operation of step S3 in a plan view of the base 210 is θ1, the angle between the second line segment L2 and the nozzle row direction DN during the execution of the capping operation of step S6 is θ2, and the angle between the first line segment L1 and the second line segment L2 is θ3, it is preferable to satisfy the relationship |θ1-θ2|<θ3. Here, the nozzle row direction DN is the arrangement direction of the multiple nozzles N in a plan view of the base 210. The first line segment L1 is a virtual line segment connecting the head 3a and the base 210 during the execution of the printing operation of step S3 in a plan view of the base 210. The second line segment L2 is a virtual line segment connecting the head 3a and the base 210 during the execution of the capping operation of step S6 in a plan view of the base 210.

[0101] When the angles θ1, θ2 and θ3 satisfy the above-mentioned relationship, the amount of rotation of the joint 230_6 can be reduced when moving the head 3a between the positions for performing the capping operation of step S6 and the printing operation of step S3, compared to when the yaw angle of the head 3a is equal during the capping operation of step S6 and during the printing operation of step S3.

[0102] In the three-dimensional object printing apparatus 1, when the two positions through which the head 3a passes during the printing operation of step S3 are the first position P1 and the second position P2, it is preferable that the pitch angle of the head 3a at the first position P1 and the pitch angle at the second position P2 are different from each other. In this case, even if the printing surface of the workpiece W is a curved surface, the attitude of the head 3a with respect to the target portion of the printing surface can be kept constant. Therefore, there is an advantage that the image quality can be easily improved regardless of the shape of the printing surface of the workpiece W.

[0103] Here, it is preferable that the printing operation of step S3 includes an operation of changing the position of the head 3a with respect to the workpiece W while maintaining the yaw angle and roll angle of the head 3a constant. In this case, it is possible to reduce unevenness in density of the ink ejected from the head 3a to the workpiece W during the execution of the printing operation of step S3. As a result, there is an advantage in that it is easier to improve image quality.

[0104] Furthermore, the three-dimensional object printing apparatus 1 further executes the first movement operation of step S2 as described above. In the first movement operation of step S2, the robot 2 moves the head 3a within the period between the end of the capping operation of step S6 and the start of the printing operation of step S3. Therefore, the first movement operation of step S2 makes it possible to transition from the capping operation of step S6 to the printing operation of step S3.

[0105] In addition, the amount of rotation of the joint 230_6 during the execution period of the first moving operation of step S2 is smaller than the amount of rotation of the joint 230_1 during the execution period of the first moving operation of step S2. Here, the joint 230_1 is an example of a "first joint" and is the joint 230 closest to the base 210 among the multiple joints 230. The joint 230_6 is an example of a "second joint" and is the joint 230 farthest from the base 210 among the multiple joints 230. When the joint 230_6 rotates, the wirings such as the above-mentioned supply pipe 10a and the drive wiring 11a related to the head 3a are more likely to be twisted than when the joint 230_1 rotates. Therefore, by making the amount of rotation of the joint 230_6 during the execution period of the first moving operation of step S2 smaller than the joint 230_1 during the execution period of the first moving operation of step S2, it is possible to reduce the twisting of the wirings in the first moving operation of step S2.

[0106] Furthermore, the three-dimensional object printing apparatus 1 further executes the second movement operation of step S5 as described above. In the second movement operation of step S5, the robot 2 moves the head 3a during the period between the end of the printing operation of step S3 and the start of the capping operation of step S6. Therefore, the second movement operation of step S5 allows the transition from the printing operation of step S3 to the capping operation of step S6 to be made.

[0107] In addition, the amount of rotation of the joint 230_6 during the execution period of the second movement operation of step S5 is smaller than the amount of rotation of the joint 230_1 during the execution period of the second movement operation of step S5. Therefore, similar to the first movement operation of step S2 described above, twisting of the wiring in the second movement operation of step S5 can be reduced.

[0108] The change in the yaw angle of the head 3a during the execution of the first movement operation of step S2 or the second movement operation of step S5 is preferably 45° or more, and more preferably 90° or more. The greater the change in the yaw angle, the greater the separation between the position of the head unit 3 during the execution of the capping operation of step S6 and the position of the workpiece W during the execution of the printing operation of step S3. This makes it possible to suppress interference by the head unit 3 when performing tasks such as installing or removing the workpiece W or adjusting the position of the workpiece W during the execution of the capping operation.

[0109] Furthermore, as described above, when the capping operation in step S6 is completed, the head 3a moves away from the cap portion 4b in the normal direction of the nozzle surface F. This reduces the movement of the nozzle surface F in contact with the cap portion 4b when the capping operation in step S6 is completed, thereby preventing the nozzle surface F from being soiled by ink adhering to the cap portion 4b.

[0110] From a similar perspective, as described above, when the capping operation in step S6 is started, the head 3a approaches the cap portion 4b along the normal direction of the nozzle surface F. Therefore, when the capping operation in step S6 is started, the nozzle surface F is less likely to move while in contact with the cap portion 4b, which prevents the nozzle surface F from being soiled by ink adhering to the cap portion 4b.

[0111] As described above, it is preferable that the nozzle surface F is horizontal during the capping operation in step S6. In this case, the meniscus of the ink in each nozzle N is stabilized during the capping operation in step S6, so the ink is less likely to thicken near each nozzle N compared to when the nozzle surface F is inclined relative to the horizontal plane.

[0112] As described above, the three-dimensional object printing apparatus 1 of this embodiment further includes the biasing mechanism 4b3. The biasing mechanism 4b3 biases the cap portion 4b toward the nozzle surface F during the capping operation of step S6. This allows the cap portion 4b and the nozzle surface F to be stably brought into close contact with each other during the capping operation of step S6.

[0113] As described above, the three-dimensional object printing apparatus 1 of this embodiment further includes the suction mechanism 4d. The suction mechanism 4d reduces the pressure in the space formed between the cap portion 4b and the nozzle surface F during the capping operation of step S6. Therefore, the ink that has thickened or solidified near the nozzle N can be removed by the action of the suction mechanism 4d.

[0114] Furthermore, the three-dimensional object printing apparatus 1 of this embodiment further includes the wiper unit 4e, as described above. The wiper unit 4e is disposed adjacent to the cap unit 4b, and wipes the nozzle surface F. Therefore, ink adhering to the nozzle surface F can be removed by the action of the wiper unit 4e. In particular, since the wiper unit 4e is disposed adjacent to the cap unit 4b, maintenance using both the cap unit 4b and the wiper unit 4e can be efficiently performed.

[0115] 2. 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 illustrated below. Note that two or more embodiments selected from the following exemplary embodiments can be appropriately combined as long as they are not contradictory to each other.

[0116] 2-1. Variation 1 In the above-mentioned embodiment, a configuration in which a six-axis vertical multi-axis robot is used as the robot is exemplified, but the configuration is not limited to this. The robot 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 the like in addition to a rotating part constituted by a rotating mechanism. However, from the viewpoint of the balance between the print quality in the printing operation and the degree of freedom of the robot's operation in the non-printing operation, it is preferable that the robot be a multi-axis robot with six or more axes.

[0117] 2-2. Variation 2 In the above embodiment, the head may be fixed to the robot by gripping the head with a gripping mechanism such as a hand attached as an end effector of the robot, but the present invention is not limited to this configuration.

[0118] 2-3. Variation 3 In the above-described embodiment, a configuration in which printing is performed using one type of ink is exemplified, but the present invention is not limited to this configuration and can also be applied to a configuration in which printing is performed using two or more types of ink.

[0119] 2-4. Variation 4 The use of the three-dimensional printing device of the present invention is not limited to printing. For example, a three-dimensional printing device that ejects a solution of a color material is used as a manufacturing device for forming a color filter of a liquid crystal display device. Also, a three-dimensional printing device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes of a wiring board. Also, a three-dimensional printing device can be used as a jet dispenser that applies a liquid such as an adhesive to a workpiece. [Explanation of symbols]

[0120] 1...3D object printing device, 2...robot, 2a...arm drive mechanism, 3...head unit, 3a...head, 3b...pressure regulating valve, 3c...curing light source, 3d...distance sensor, 3e...switch circuit, 3f...support, 4...maintenance unit, 4a...case, 4b...cap portion, 4b1...cap, 4b2...guide portion, 4b3...urging mechanism, 4c...support stand, 4c1...top surface portion, 4c2...leg, 4d...suction mechanism, 4d2...pressure reduction pump, 4e...wiper portion, 4e1...wiper, 4e2...support, 5...controller, 5 a...memory circuit, 5b...processing circuit, 6...control module, 6a...timing signal generating circuit, 6b...power supply circuit, 6c...control circuit, 6d...drive signal generating 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 section (first rotating section, rotating section), 230_1...joint section (rotating section), 230_2...joint section (rotating section), 230 _3... joint (rotating part), 230_4... joint (rotating part), 230_5... joint (rotating part), 230_6... joint (second rotating part, rotating part), AX... long axis, CLK... clock signal, CNG... change signal, Com... drive signal, D1... output, D3... signal, DN... nozzle row direction, DS... scanning direction, Da... path information, F... nozzle surface, FX1... fixed position, FX2... fixed position, FX3... fixed position, FX4... fixed position, L1... first line segment, L2... second line segment, LAT... latch signal, La... nozzle row, Lb... nozzle row , N...nozzle, O1...rotation axis, O2...rotation axis, O3...rotation axis, O4...rotation axis, O5...rotation axis, O6...rotation axis, P1...first position, P2...second position, PD...driving pulse, PTS...timing signal, RU...movement path, S1...step, S2...step, S3...step, S4...step, S5...step, S6...step, S7...step, SI...control signal, Sk1...control signal, VBS...offset potential, VHV...power supply potential, W...work, WF...surface, dCom...waveform specification signal, θ1...angle, θ2...angle.

Claims

1. a head having a nozzle surface provided with a plurality of nozzles for ejecting liquid; The head has a base and an arm that supports the head. The base and the arm are connected in a number of turns. A rotating part is provided, and the position of the head with respect to the base is changed by rotating the rotating part. A robot that a cap portion that covers the nozzle surface; having The robot positions the head at a position where the nozzle surface is covered by the cap portion. The cap action causes the The robot changes the position of the head relative to the workpiece differently during the capping operation. A printing operation in which the head ejects liquid onto the workpiece while changing the position of the head. Run, The yaw angle of the head during the capping operation and the yaw angle of the head during the printing operation are The yaw angles of the heads are different from each other. A three-dimensional object printing device.

2. The two positions through which the head passes during the execution of the printing operation are referred to as a first position and a second position. When you do, The pitch angle of the head at the first position is different from the pitch angle at the second position. 、 2. The three-dimensional object printing apparatus according to claim 1 .

3. The printing operation is performed by applying a laser beam to the workpiece while maintaining the yaw angle and roll angle of the head constant. changing the position of the head relative to the 3. The three-dimensional object printing device according to claim 1 or 2.

4. In a plan view of the base, an arrangement direction of the plurality of nozzles is a nozzle row direction, A virtual line segment connecting the head and the base during the printing operation is defined as a first line segment. 、 an angle between the first line segment and the nozzle row direction during the printing operation is θ1; A virtual line segment connecting the head and the base during the capping operation is defined as a second line segment. year, The angle between the second line segment and the nozzle row direction during the capping operation is θ2. death, When the angle between the first line segment and the second line segment is θ3, |θ1-θ2|<θ3 Satisfy the relationship The three-dimensional object printing device according to any one of claims 1 to 3.

5. The robot is operated within a period from the end of the capping operation to the start of the printing operation. the controller further performs a first moving operation to move the head; Among the plurality of rotating parts, a first pivot portion being a pivot portion closest to the base portion; When the rotating part farthest from the base part is defined as a second rotating part, The rotation amount of the second rotation part during the execution period of the first moving operation is is smaller than the rotation amount of the first rotation unit over the execution period, The three-dimensional object printing device according to any one of claims 1 to 4.

6. The robot is operated within a period from the end of the printing operation to the start of the capping operation. the controller further performs a second moving operation to move the head; The rotation amount of the second rotation part during the execution period of the second moving operation is is smaller than the rotation amount of the first rotation unit over the execution period, 6. The three-dimensional object printing apparatus according to claim 5.

7. A change in the yaw angle of the head during the execution of the first movement operation or the second movement operation. The angle is 45° or more.

7. The three-dimensional object printing apparatus according to claim 6.

8. A change in the yaw angle of the head during the execution of the first movement operation or the second movement operation. The angle is 90° or more.

8. The three-dimensional object printing apparatus according to claim 7.

9. When the capping operation is completed, the head moves forward along the normal direction of the nozzle surface. The cap portion is spaced apart from the cap portion. The three-dimensional object printing device according to any one of claims 1 to 8.

10. When the capping operation is started, the head moves forward along the normal direction of the nozzle surface. Approaching the cap portion, The three-dimensional object printing device according to any one of claims 1 to 9.

11. the nozzle face is horizontal during the capping operation; The three-dimensional object printing device according to any one of claims 1 to 10.

12. a biasing mechanism for biasing the cap portion toward the nozzle surface during the capping operation; Further comprising The three-dimensional object printing device according to any one of claims 1 to 11.

13. A space formed between the cap portion and the nozzle surface during the capping operation is Further comprising a suction mechanism for reducing pressure. The three-dimensional object printing device according to any one of claims 1 to 12.

14. The ink jet head further includes a wiper portion disposed adjacent to the cap portion and configured to wipe the nozzle surface. do, The three-dimensional object printing device according to any one of claims 1 to 13.

15. A supply pipe for supplying liquid to the head is further provided. The supply tube is provided outside the arm. The three-dimensional object printing device according to any one of claims 1 to 14.

16. a drive wiring for supplying an electric signal for driving the head to the head; The drive wiring is provided outside the arm portion. The three-dimensional object printing device according to any one of claims 1 to 15.

17. a head having a nozzle surface provided with a plurality of nozzles for ejecting liquid; The head has a base and an arm that supports the head. The base and the arm are connected in a number of turns. A rotating part is provided, and the position of the head with respect to the base is changed by rotating the rotating part. A robot that a cap portion that covers the nozzle surface; A three-dimensional object printing method using The robot positions the head at a position where the nozzle surface is covered by the cap portion. The cap action causes the The robot changes the position of the head relative to the workpiece differently during the capping operation. A printing operation in which the head ejects liquid onto the workpiece while changing the position of the head. Run, The yaw angle of the head during the capping operation and the yaw angle of the head during the printing operation are The yaw angles of the heads are different from each other. A three-dimensional object printing method.

Images