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

Abstract

To enhance an image quality of printing on a three-dimensional work-piece.SOLUTION: A three-dimensional object printing device comprises: a liquid discharge head that discharges liquid to a three-dimensional work-piece; a moving mechanism that changes a relative position of the liquid discharge head with respect to the work-piece or an object corresponding to the work-piece; and a detecting part that detects the relative position of the liquid discharge head with respect to the work-piece or the object, which executes first detection operation by which the detecting part detects a position concerning a first scanning route, while the moving mechanism scans the liquid discharge head along the first scanning route with respect to the work-piece or the object, and first printing operation by which the liquid discharge head discharges liquid to a first region of the work-piece, while the moving mechanism scans the liquid discharge head along a second scanning route on the basis of a detected result by the detecting part in the first detection operation.SELECTED DRAWING: Figure 2

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 moves an inkjet printhead by combining the movements of multiple movable parts to perform inkjet printing on the surface of a three-dimensional object. For example, the device described in Patent Document 1 includes a robot arm with multiple movable parts, an inkjet printhead attached to the tip of the robot arm, and a controller that controls the movement of the robot arm. Here, the controller controls the movement of the robot arm so that the inkjet printhead moves along a series of scanning paths. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-111307 Summary of the Invention [Problem to be solved by the invention]

[0004] When an inkjet print head is moved linearly along a scanning path by combining the movements of multiple movable parts, the following problem may occur: Even if an ideal path is simply provided to the controller as an instruction for the path along which the inkjet print head should move, operational errors of each joint part will appear at various times along the scanning path, causing the actual path to deviate from the ideal path in a meandering manner, resulting in a problem of degraded print quality. [Means for solving the problem]

[0005] In order to solve the above problems, one aspect of a three-dimensional object printing device according to the present invention comprises a liquid ejection head that ejects liquid onto a three-dimensional workpiece, a movement mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, and a detection unit that detects the relative position of the liquid ejection head with respect to the workpiece or the object, and performs a first detection operation in which the movement mechanism scans the liquid ejection head relative to the workpiece or the object along a first scanning path while the detection unit detects the position with respect to the first scanning path, and a first printing operation in which the movement mechanism scans the liquid ejection head relative to the workpiece along a second scanning path based on the detection result by the detection unit in the first detection operation while the liquid ejection head ejects liquid onto a first region of the workpiece.

[0006] Another aspect of the three-dimensional object printing device of the present invention comprises a liquid ejection head that ejects liquid onto a three-dimensional workpiece, a movement mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, and a detection unit that detects the relative position of the liquid ejection head with respect to the workpiece or the object, and performs a first detection operation in which the movement mechanism scans the liquid ejection head relative to the workpiece or the object along a first scanning path while the detection unit detects a position with respect to the first scanning path, and a first printing operation in which the movement mechanism scans the liquid ejection head relative to the workpiece along a second scanning path while the liquid ejection head ejects liquid onto a first region of the workpiece, and when the amount of deviation of the first scanning path from a reference path is a first amount, the path difference between the first scanning path and the second scanning path is a first path difference, and when the amount of deviation is a second amount greater than the first amount, the path difference is a second path difference greater than the first path difference.

[0007] One aspect of the three-dimensional object printing method of the present invention is a three-dimensional object printing method that prints on a three-dimensional workpiece using a liquid ejection head that ejects liquid onto the workpiece and a movement mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, wherein the movement mechanism performs a first detection operation in which the liquid ejection head scans the liquid ejection head relative to the workpiece or the object along a first scanning path while detecting a position relative to the first scanning path, and a first printing operation in which the liquid ejection head ejects liquid onto a first area of ​​the workpiece while the movement mechanism scans the liquid ejection head relative to the workpiece along a second scanning path based on the detection result of the first detection operation.

[0008] Another aspect of the three-dimensional object printing method of the present invention is a three-dimensional object printing method that prints on a three-dimensional workpiece using a liquid ejection head that ejects liquid onto the workpiece and a movement mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, wherein the movement mechanism performs a first detection operation in which the liquid ejection head scans the liquid ejection head relative to the workpiece or the object along a first scanning path while detecting a position related to the first scanning path, and a first printing operation in which the liquid ejection head scans the liquid ejection head relative to the workpiece along a second scanning path while the movement mechanism scans the liquid ejection head relative to the workpiece, and ejects liquid onto a first region of the workpiece; when the deviation amount of the first scanning path with respect to a reference path is a first amount, the path difference between the first scanning path and the second scanning path is a first path difference; and when the deviation amount is a second amount greater than the first amount, the path difference is a second path difference greater than the first path difference. [Brief explanation of the drawings]

[0009] [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. 1 is a perspective view showing a schematic configuration of a liquid ejection head unit according to a first embodiment. [Figure 4] 1 is a cross-sectional view showing an example of the configuration of a liquid ejection head according to a first embodiment. [Figure 5] 4 is a flowchart showing the flow of a three-dimensional object printing method according to the first embodiment. [Figure 6] 6 is a flowchart showing the flow of generating the point data shown in FIG. 5. [Figure 7] 5A to 5C are diagrams for explaining a detection operation and a printing operation in the first embodiment. [Figure 8] FIG. 10 is a diagram for explaining point data indicating an ideal scanning path. [Figure 9] 10A and 10B are diagrams for explaining detection of positions on an actual scanning path when point data indicating an ideal scanning path is used. [Figure 10] FIG. 10 is a diagram for explaining deviation of an actual scanning path from an ideal scanning path. [Figure 11] 10A and 10B are diagrams for explaining an example of point data corrected based on an actual scanning path. [Figure 12] 10A and 10B are diagrams for explaining another example of point data corrected based on an actual scanning path. [Figure 13] FIG. 10 is a diagram for explaining an actual scanning path when corrected point data is used. [Figure 14] FIG. 10 is a diagram for explaining detection of an actual scanning path in a subsequent pass. [Figure 15] FIG. 10 is a diagram for explaining a scanning path after correction in a subsequent pass. [Figure 16] FIG. 10 is a block diagram showing the electrical configuration of a three-dimensional object printing device according to a second embodiment. [Figure 17] FIG. 10 is a diagram for explaining detection of an actual scanning path in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention 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 some parts are shown schematically 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.

[0011] The following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. Furthermore, one direction along the X-axis will be referred to as the X1 direction, and the direction opposite the X1 direction will be referred to as the X2 direction. Similarly, opposite directions along the Y-axis will be referred to as the Y1 direction and the Y2 direction. Furthermore, opposite directions along the Z-axis will be referred to as the Z1 direction and the Z2 direction.

[0012] Here, the X-axis, Y-axis, and Z-axis are coordinate axes of a base coordinate system set in a space in which the workpiece W and base 210 (described later) are installed. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. Note that the Z-axis does not have to be a vertical axis. Furthermore, the X-axis, Y-axis, and Z-axis are typically perpendicular to each other, but are not limited to this and may not be perpendicular. For example, the X-axis, Y-axis, and Z-axis may intersect each other at an angle within a range of 80° to 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 100 according to the first embodiment. The three-dimensional object printing apparatus 100 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 a flat surface facing the Z1 direction. The printing target may be any surface other than the surface WF among the multiple surfaces of the workpiece W. Furthermore, the size, shape, and installation orientation of the workpiece W are not limited to the example shown in FIG. 1 and are arbitrary.

[0015] Here, in the detection operation MD described below, an object O corresponding to the workpiece W is used as needed. The object O is an object having a surface OF with substantially the same shape and orientation as the surface WF. For example, the object O is an object with substantially the same shape as the workpiece W, and is placed in place of the workpiece W with substantially the same orientation as the workpiece W. Note that the object O may also be a film peelably attached to the surface WF of the workpiece W. If needed, the film may be provided with a receiving layer to facilitate ink absorption.

[0016] In the example shown in Fig. 1, the three-dimensional object printing apparatus 100 is an inkjet printer that uses a vertical articulated robot. Specifically, as shown in Fig. 1, the three-dimensional object printing apparatus 100 has a robot 200, a liquid ejection head unit 300, a liquid storage section 400, a supply flow path 500, and a control device 600. Below, each section of the three-dimensional object printing apparatus 100 will be briefly described in order.

[0017] The robot 200 is an example of a movement mechanism that changes the position and posture of the liquid ejection head unit 300 relative to the workpiece W. In the example shown in Fig. 1, the robot 200 is a so-called six-axis vertical articulated robot. Specifically, the robot 200 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 that faces the Z1 direction. The installation surface to which base 210 is fixed may be a surface that faces 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, which are connected in this order.

[0020] Arm 221 is connected to base 210 via joint 231 so as to be rotatable around a first rotation axis O1. Arm 222 is connected to arm 221 via joint 232 so as to be rotatable around a second rotation axis O2. Arm 223 is connected to arm 222 via joint 233 so as to be rotatable around a third rotation axis O3. Arm 224 is connected to arm 223 via joint 234 so as to be rotatable around a fourth rotation axis O4. Arm 225 is connected to arm 224 via joint 235 so as to be rotatable around a fifth rotation axis O5. Arm 226 is connected to arm 225 via joint 236 so as to be rotatable around a sixth rotation axis O6.

[0021] In the example shown in FIG. 1, each of the joints 231-236 is a mechanism that rotatably connects one of two adjacent arms relative to the other. Although not shown, each of the joints 231-236 is provided with a drive mechanism that rotates one of the two adjacent arms 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 the angle of the rotation. The drive mechanism corresponds to the arm drive mechanism 230 shown in FIG. 2, which will be described later.

[0022] The first rotation axis O1 is an axis perpendicular to an installation surface (not shown) to which the base 210 is fixed. The second rotation axis O2 is an axis perpendicular to the first rotation axis O1. The third rotation axis O3 is an axis parallel to the second rotation axis O2. The fourth rotation axis O4 is an axis perpendicular to the third rotation axis O3. The fifth rotation axis O5 is an axis perpendicular to the fourth rotation axis O4. The sixth rotation axis O6 is an axis perpendicular to the fifth rotation axis O5.

[0023] 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°.

[0024] A liquid ejection head unit 300 is attached as an end effector to the tip of the arm 221, that is, to the arm 226.

[0025] The liquid ejection head unit 300 is a mechanism having a liquid ejection head 310 that ejects ink, which is an example of a liquid, toward the workpiece W. In this embodiment, in addition to the liquid ejection head 310, the liquid ejection head unit 300 also has a pressure adjustment valve 320 that adjusts the pressure of the ink supplied to the liquid ejection head 310, and an imaging device 330 that images the surface WF of the workpiece W or the surface OF of the object O. These are all fixed to the arm 226, so the relative positions and orientations of these are fixed.

[0026] The liquid ejection head 310 will be described in detail later. The pressure adjustment valve 320 is a valve mechanism that opens and closes in response to the pressure of the ink inside the liquid ejection head 310. This opening and closing maintains the ink pressure inside the liquid ejection head 310 at a negative pressure within a predetermined range. This stabilizes the ink meniscus formed in the nozzle N of the liquid ejection head 310. As a result, it is possible to prevent air bubbles from entering the nozzle N and ink from overflowing from the nozzle N.

[0027] 1, the liquid ejection head unit 300 has one liquid ejection head 310 and one pressure adjustment valve 320, but the numbers are not limited to those shown in Fig. 1 and may be two or more. Furthermore, the installation positions of the pressure adjustment valve 320 and the imaging device 330 are not limited to the arm 226 and may be, for example, on another arm or the like, or may be fixed positions relative to the base 210.

[0028] The imaging device 330 has, for example, an imaging optical system and an imaging element. The imaging optical system is an optical system including at least one imaging lens, and may include various optical elements such as a prism, or may include a zoom lens or a focus lens. The imaging element is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor.

[0029] The liquid storage unit 400 is a container that stores ink. The liquid storage unit 400 is, for example, a bag-shaped ink pack made of a flexible film. The ink stored in the liquid storage unit 400 is, for example, an ink containing a coloring material such as a dye or a pigment. The type of ink stored in the liquid storage unit 400 is not limited to ink containing a coloring material, and may be, for example, an ink containing a conductive material such as metal powder. The ink may also be curable, for example, with ultraviolet light. When the ink is curable, for example, with ultraviolet light, the liquid ejection head unit 300 is equipped with an ultraviolet light irradiation mechanism, for example.

[0030] 1, the liquid storage unit 400 is fixed to a wall, ceiling, pillar, or the like so that it is always located further in the Z1 direction than the liquid ejection head 310. In other words, the liquid storage unit 400 is located vertically above the movement area of ​​the liquid ejection head 310. Therefore, ink can be supplied from the liquid storage unit 400 to the liquid ejection head 310 with a predetermined pressure without using a mechanism such as a pump.

[0031] The liquid storage unit 400 may be located vertically below the liquid ejection head 310 as long as it can supply ink from the liquid storage unit 400 to the liquid ejection head 310 at a predetermined pressure. In this case, for example, a pump may be used to supply ink from the liquid storage unit 400 to the liquid ejection head 310 at a predetermined pressure.

[0032] The supply flow path 500 is a flow path that supplies ink from the liquid storage section 400 to the liquid ejection head 310. A pressure adjustment valve 320 is provided midway along the supply flow path 500. Therefore, even if the positional relationship between the liquid ejection head 310 and the liquid storage section 400 changes, fluctuations in the ink pressure inside the liquid ejection head 310 can be reduced.

[0033] The supply flow path 500 is divided into an upstream flow path 510 and a downstream flow path 520 by the pressure adjustment valve 320. That is, the supply flow path 500 has the upstream flow path 510 that connects the liquid storage section 400 and the pressure adjustment valve 320, and the downstream flow path 520 that connects the pressure adjustment valve 320 and the liquid ejection head 310.

[0034] Each of the upstream flow path 510 and the downstream flow path 520 is formed, for example, by the internal space of a tubular body. Here, the tubular body used for the upstream flow path 510 is made of an elastic material such as a rubber material or an elastomer material and has flexibility. By forming the upstream flow path 510 using a flexible tubular body in this way, changes in the relative positional relationship between the liquid storage section 400 and the pressure adjustment valve 320 are permitted. Therefore, even if the position or attitude of the liquid ejection head 310 changes while the position and attitude of the liquid storage section 400 remain fixed, ink can be supplied from the liquid storage section 400 to the pressure adjustment valve 320. On the other hand, the tubular body used for the downstream flow path 520 does not have to be flexible. Therefore, the tubular body used for the downstream flow path 520 may be made of an elastic material such as a rubber material or an elastomer material, or may be made of a hard material such as a resin material.

[0035] Note that a portion of the upstream flow path 510 may be made of a non-flexible material. Furthermore, the downstream flow path 520 is not limited to a configuration using a tubular body. For example, a portion or all of the downstream flow path 520 may be configured to have a distribution flow path that distributes ink from the pressure adjustment valve 320 to multiple locations, or may be configured integrally with the liquid ejection head 310 or the pressure adjustment valve 320.

[0036] The control device 600 is a device that controls the driving of each part of the three-dimensional object printing apparatus 100. Here, the control device 600 is a robot controller that controls the driving of the liquid ejection head 310 and the robot 200. The control device 600 will be described in detail below together with the explanation of the electrical configuration of the three-dimensional object printing apparatus 100.

[0037] 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 100 according to the first embodiment. Fig. 2 shows the electrical components of the three-dimensional object printing device 100. As shown in Fig. 2, the control device 600 has a processing circuit 610, a memory circuit 620, a power supply circuit 630, and a drive signal generation circuit 640.

[0038] The hardware configuration included in the control device 600 described below may be divided as appropriate. For example, the arm control unit 612 and the drive signal generating circuit 640 of the control device 600 may be provided separately in different hardware configurations. Also, some or all of the functions of the control device 600 may be implemented by an external device 700 connected to the control device 600, or may be implemented by another external device such as a PC (personal computer) connected to the control device 600 via a network such as a LAN (Local Area Network) or the Internet.

[0039] The processing circuitry 610 has the function of controlling the operation of each part of the three-dimensional object printing device 100 and the function of processing various types of data. The processing circuitry 610 includes, for example, one or more processors such as a CPU (Central Processing Unit). Note that the processing circuitry 610 may include a programmable logic device such as an FPGA (Field-Programmable Gate Array) instead of or in addition to a CPU.

[0040] The memory circuitry 620 stores various programs, such as the program PG1, executed by the processing circuitry 610, and various data, such as work information Da, imaging information Db, and point data Dc, processed by the processing circuitry 610. The memory circuitry 620 includes, for example, one or both of semiconductor memories: 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). The memory circuitry 620 may be configured as part of the processing circuitry 610.

[0041] The work information Da is information indicating the position and shape of the surface WF of the work W. The work information Da is, for example, information such as CAD (computer-aided design) data indicating the three-dimensional shape of the work W associated with the base coordinate system described above. Here, since the object O corresponds to the work W as described above, the work information Da can also be said to be information indicating the position and shape of the surface OF of the object O. The work information Da is generated by the data generation unit 614, which will be described later. Furthermore, the information indicating the three-dimensional shape of the work W is, for example, included in the print data Img, or is input to the control device 600 from the external device 700 separately from the print data Img.

[0042] The imaging information Db is information indicating the imaging results of the imaging device 330. The imaging information Db indicates, for example, the luminance for each coordinate value of a camera coordinate system set in the imaging device 330. Note that the camera coordinate system may or may not be associated with the aforementioned base coordinate system in advance by calibration.

[0043] The point data Dc is information indicating positions through which the liquid ejection head 310 must pass. The point data Dc indicates, for example, the scanning path of the liquid ejection head 310 relative to the workpiece W or the object O, using coordinate values ​​in a base coordinate system. The point data Dc is generated by a data generation unit 614, which will be described later.

[0044] The power supply circuit 630 receives power from a commercial power supply (not shown) and generates various predetermined potentials. The generated potentials are supplied appropriately to each section of the three-dimensional object printing device 100. For example, the power supply circuit 630 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection head unit 300. The power supply potential VHV is also supplied to the drive signal generation circuit 640.

[0045] The drive signal generation circuit 640 is a circuit that generates a drive signal Com for driving each piezoelectric element 311 of the liquid ejection head 310. Specifically, the drive signal generation circuit 640 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 640, the DA conversion circuit converts a waveform designation signal dCom (described later) from a digital signal to an analog signal from the processing circuit 610, and the amplifier circuit amplifies the analog signal using a power supply potential VHV from the power supply circuit 630 to generate the drive signal Com. Here, of the waveforms included in the drive signal Com, a signal with a waveform that is actually supplied to the piezoelectric element 311 is a drive pulse PD. The drive pulse PD is supplied from the drive signal generation circuit 640 to the piezoelectric element 311 via a drive circuit 340 that drives the piezoelectric element 311. The drive circuit 340 switches whether or not to supply at least a portion of the waveform included in the drive signal Com as the drive pulse PD based on a control signal SI (described later).

[0046] In the control device 600 described above, the processing circuitry 610 executes the program PG1 stored in the memory circuitry 620 to control the operation of each unit of the three-dimensional object printing device 100. Specifically, by executing the program PG1, the processing circuitry 610 functions as an information acquisition unit 611, an arm control unit 612, a discharge control unit 613, a data generation unit 614, and a detection unit 615.

[0047] The information acquisition unit 611 acquires various pieces of information necessary for driving the robot 200 and the liquid ejection head unit 300. Specifically, the information acquisition unit 611 acquires print data Img from the external device 700, information D1 from the encoder included in the arm drive mechanism 230, imaging information Db from the imaging device 300, and information such as work information Da and point data Dc from the memory circuit 620. The information acquisition unit 611 also stores the various pieces of information acquired in the memory circuit 620 as appropriate.

[0048] The arm control unit 612 controls the driving of the robot 200 based on the information from the information acquisition unit 611. Specifically, the arm control unit 612 generates a control signal Sk based on the information D1, the workpiece information Da, and the point data Dc. The control signal Sk controls the driving of the motor included in the arm driving mechanism 230 so that the liquid ejection head 310 is in a desired position and posture.

[0049] The correspondence between the information D1 and the position and orientation of the liquid ejection head is acquired in advance by calibration or the like and stored in the memory circuit 620. The arm control unit 612 then acquires information about the actual position and orientation of the liquid ejection head 310 based on the information D1 from the actual arm drive mechanism 230 and this correspondence. The arm control unit 612 then uses this information about the position and orientation to control the liquid ejection head 310 so that it is positioned and oriented as desired. The arm control unit 612 may also use information from a displacement sensor (not shown) to appropriately adjust the control signal Sk so that the distance between the liquid ejection head 310 and the surface of the workpiece W is maintained within a predetermined range.

[0050] The ejection control unit 613 controls the driving of the liquid ejection head unit 300 based on information from the information acquisition unit 611. Specifically, the ejection control unit 613 generates a control signal SI and a waveform designation signal dCom based on the print data Img. The control signal SI is a digital signal for designating the operating state of a piezoelectric element 311 (described below) included in the liquid ejection head 310. Here, the control signal SI may include other signals, such as a timing signal for determining the drive timing of the piezoelectric element 311. The timing signal is generated based on information D1 from an encoder included in the arm drive mechanism 230, for example. The waveform designation signal dCom is a digital signal for determining the waveform of the drive signal Com. The print data Img is information representing a two-dimensional or three-dimensional image, and is supplied from an external device 700, such as a personal computer.

[0051] The drive control of the liquid ejection head 310 by the ejection control unit 613 as described above is performed in synchronization with the drive control of the robot 200 by the arm control unit 612. Here, the robot 200 scans the liquid ejection head 310 in a predetermined direction relative to the surface WF, and the liquid ejection head 310 ejects ink, thereby printing an image in ink on the surface WF of the workpiece W.

[0052] The data generation unit 614 generates point data Dc. As will be described in detail later, the data generation unit 614 generates workpiece information Da, generates point data Dc indicating an ideal scanning path based on the workpiece information Da, and then corrects the point data Dc indicating the ideal scanning path based on the detection results of the detection unit 615. The ideal scanning path corresponds to, for example, reference paths RU_1 and RU_2 described below. Here, the workpiece information Da is generated by recognizing the workpiece W using a sensor or camera (not shown) calibrated to the aforementioned base coordinate system, as described above, and associating information indicating the three-dimensional shape of the workpiece W with the aforementioned base coordinate system.

[0053] The detection unit 615 detects the relative position of the liquid ejection head 310 with respect to the workpiece W or the object O. This detection is performed in a detection operation MD (described later) that detects the actual scanning path of the liquid ejection head 310, prior to a printing operation MP (described later) that prints an image based on the print data Img. As will be described in detail later, the detection unit 615 of this embodiment uses the imaging results of the imaging device 330 to detect the position of the liquid ejection head 310 with respect to the workpiece W or the object O. Here, the detection operation MD of this embodiment involves printing a detection pattern on the workpiece W or the object O while driving the robot 200 using the point data Dc that indicates the ideal scanning path described above, then imaging the detection pattern with the imaging device 330, and detecting the position with respect to the scanning path using the imaging results.

[0054] An image based on the print data Img is formed by N printing operations MP (N is a natural number greater than or equal to 1), which indicates the number of passes. The detection operation MD is performed N times, corresponding to the number of printing operations MP. Below, the first-pass printing operation MP is referred to as "printing operation MP_N," and the Nth-pass detection operation MD is referred to as "printing operation MD_N." Here, the first-pass printing operation MP is the first printing operation MP_1. The second-pass printing operation MP is the second printing operation MP_2. The first-pass detection operation MD is the first detection operation MD_1. The second-pass detection operation MD is the second detection operation MD_2. Also, below, the point data Dc used in the Nth pass may be referred to as point data Dc_N.

[0055] 1-3. Liquid ejection head unit FIG. 3 is a perspective view showing a schematic configuration of a liquid ejection head unit 300 according to the embodiment.

[0056] In the following explanation, the mutually intersecting a-axis, b-axis, and c-axis will be used as appropriate. Furthermore, one direction along the a-axis will be referred to as the a1 direction, and the direction opposite the a1 direction will be referred to as the a2 direction. Similarly, the opposite directions along the b-axis will be referred to as the b1 direction and the b2 direction. Furthermore, the opposite directions along the c-axis will be referred to as the c1 direction and the c2 direction.

[0057] Here, the a-axis, b-axis, and c-axis are coordinate axes of a tool coordinate system set in the liquid ejection head unit 300, and the relative position and orientation relationships with the X-axis, Y-axis, and Z-axis change depending on the operation of the robot 200. In the example shown in Fig. 3, the c-axis is an axis parallel to the sixth rotation axis O6. Note that the a-axis, b-axis, and c-axis are typically perpendicular to each other, but are not limited to this, and may intersect at an angle within a range of 80° to 100°, for example.

[0058] As described above, the liquid ejection head unit 300 has a liquid ejection head 310, a pressure adjustment valve 320, and an imaging device 330. These are supported by a support 350 indicated by a two-dot chain line in FIG.

[0059] The support 350 is made of, for example, a metal material, and is substantially rigid. Although the support 350 is shown in Fig. 3 as having a flat box shape, the shape of the support 350 is not particularly limited and may be any shape.

[0060] The support 350 is attached to the tip of the arm 220, that is, to the arm 226. Therefore, the liquid ejection head 310, the pressure adjustment valve 320, and the imaging device 330 are each fixed to the arm 226.

[0061] 3, the pressure adjustment valve 320 is positioned in the c1 direction relative to the liquid ejection head 310. The imaging device 330 is positioned in the a2 direction relative to the liquid ejection head 310.

[0062] 3, a portion of the downstream flow path 520 of the supply flow path 500 is formed by a flow path member 521. The flow path member 521 has a flow path that distributes ink from the pressure adjustment valve 320 to multiple locations in the liquid ejection head 310. The flow path member 521 is, for example, a laminate of multiple substrates made of a resin material, and grooves or holes for ink flow paths are appropriately formed in each substrate.

[0063] The liquid ejection head 310 has a nozzle surface F and a plurality of nozzles N opening in 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 a first nozzle row L1 and a second nozzle row L2 that are arranged at intervals in the direction along the a-axis. Each of the first nozzle row L1 and the second nozzle row L2 is a collection of a plurality of nozzles N linearly arranged in the direction along the b-axis. Here, in the liquid ejection head 310, elements associated with each nozzle N of the first nozzle row L1 and elements associated with each nozzle N of the second nozzle row L2 are configured to be approximately symmetrical to each other in the direction along the a-axis.

[0064] However, the positions of the multiple nozzles N in the first nozzle row L1 and the multiple nozzles N in the second nozzle row L2 in the direction along the b-axis may or may not match. Also, elements related to each nozzle N of one of the first nozzle row L1 and the second nozzle row L2 may be omitted. Below, a configuration in which the positions of the multiple nozzles N in the first nozzle row L1 and the multiple nozzles N in the second nozzle row L2 in the direction along the b-axis match will be exemplified.

[0065] 4 is a cross-sectional view showing an example of the configuration of a liquid ejection head 310 according to an embodiment. As shown in FIG. 4, the liquid ejection head 310 includes a flow path substrate 312, a pressure chamber substrate 313, a nozzle plate 314, a vibration absorber 315, a vibration plate 316, a plurality of piezoelectric elements 311, a wiring substrate 317, and a housing part 318.

[0066] The flow path substrate 312 and the pressure chamber substrate 313 form a flow path for supplying ink to the multiple nozzles N. The flow path substrate 312 and the pressure chamber substrate 313 are stacked in this order in the c1 direction. The flow path substrate 312 and the pressure chamber substrate 313 are each a plate-like member that is elongated in the direction along the b axis. The flow path substrate 312 and the pressure chamber substrate 313 are joined to each other, for example, by an adhesive.

[0067] A diaphragm 316, a wiring board 317, a housing part 318, and a drive circuit 340 are disposed in an area positioned in the c1 direction from the pressure chamber substrate 313. On the other hand, a nozzle plate 314 and a vibration absorber 315 are disposed in an area positioned in the c2 direction from the flow path substrate 312. These elements are generally plate-like members that are elongated in the direction along the b-axis, similar to the flow path substrate 312 and the pressure chamber substrate 313, and are joined together by, for example, an adhesive.

[0068] The nozzle plate 314 is a plate-like member in which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through-hole that allows ink to pass through. The nozzle plate 314 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques that employ processing techniques such as dry etching or wet etching. However, other known methods and materials may also be used as appropriate to manufacture the nozzle plate 314.

[0069] Here, the nozzle surface F mentioned above is a surface that extends along a direction perpendicular to the c-axis from an opening at one end in the c2 direction of the nozzle N, among the surfaces that constitute the outer shape of the liquid ejection head 310. In the example shown in Fig. 4, the surface of the liquid ejection head 310 facing the c2 direction is the nozzle surface F, and the nozzle surface F includes the surface of the nozzle plate 314 facing the c2 direction.

[0070] The flow path substrate 312 is provided with a space Ra, a plurality of supply flow paths 312a, a plurality of communication flow paths 312b, and a supply liquid chamber 312c for each of the first nozzle row L1 and the second nozzle row L2. The space Ra is an elongated opening extending in the direction along the b-axis in a plan view seen along the c-axis. The supply flow path 312a and the communication flow path 312b are each a through-hole formed for each nozzle N. The supply liquid chamber 312c is an elongated space extending in the direction along the b-axis across the plurality of nozzles N, and connects the space Ra and the plurality of supply flow paths 312a to each other. Each of the plurality of communication flow paths 312b overlaps with one nozzle N corresponding to that communication flow path 312b in a plan view.

[0071] The pressure chamber substrate 313 is a plate-like member in which a plurality of pressure chambers Cv, referred to as cavities, are formed for each of the first nozzle row L1 and the second nozzle row L2. The plurality of pressure chambers Cv are arranged in a direction along the b-axis. Each pressure chamber Cv is formed for each nozzle N and is an elongated space extending in a direction along the a-axis in a plan view. Like the nozzle plate 314 described above, the flow path substrate 312 and the pressure chamber substrate 313 are each manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example. However, other known methods and materials may also be used as appropriate for manufacturing the flow path substrate 312 and the pressure chamber substrate 313.

[0072] The pressure chamber Cv is a space located between the flow path substrate 312 and the vibration plate 316. A plurality of pressure chambers Cv are arranged in the direction along the b-axis for each of the first nozzle row L1 and the second nozzle row L2. The pressure chamber Cv is also in communication with each of the communication flow path 312b and the supply flow path 312a. Therefore, the pressure chamber Cv is in communication with the nozzle N via the communication flow path 312b, and is in communication with the space Ra via the supply flow path 312a and the supply liquid chamber 312c.

[0073] A diaphragm 316 is disposed on the surface of the pressure chamber substrate 313 facing the c2 direction. The diaphragm 316 is a plate-shaped member that can vibrate elastically. The diaphragm 316 has, for example, an elastic film made of silicon oxide (SiO2) and an insulating film made of zirconium oxide (ZrO2), which are laminated together. The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer.

[0074] On the surface of the vibration plate 316 facing the c1 direction, a plurality of piezoelectric elements 311 corresponding to each nozzle N in each of the first nozzle row L1 and the second nozzle row L2 are arranged. Each piezoelectric element 311 is a passive element that deforms when the aforementioned drive pulse PD is supplied. Each piezoelectric element 311 has an elongated shape extending in the direction along the a-axis in a plan view. The plurality of piezoelectric elements 311 are arranged in the direction along the b-axis so as to correspond to the plurality of pressure chambers Cv. When the vibration plate 316 vibrates in conjunction with the deformation of the piezoelectric elements 311, the pressure in the pressure chambers Cv fluctuates, causing ink to be ejected from the nozzle N in the c2 direction.

[0075] The housing 318 is a case for storing ink to be supplied to the multiple pressure chambers Cv. As shown in FIG. 4, the housing 318 of this embodiment has a space Rb formed for each of the first nozzle row L1 and the second nozzle row L2. The space Rb in the housing 318 and the space Ra in the flow path substrate 312 are connected to each other. The space formed by the space Ra and the space Rb functions as a liquid storage chamber R, which is a reservoir for storing ink to be supplied to the multiple pressure chambers Cv. Ink is supplied to the liquid storage chamber R through an inlet 318a formed in the housing 318. The ink in the liquid storage chamber R is supplied to the pressure chambers Cv via the supply liquid chamber 312c and each supply flow path 312a. The vibration absorber 315 is a flexible film-like compliance substrate that forms the wall surface of the liquid storage chamber R and absorbs pressure fluctuations of the ink in the liquid storage chamber R.

[0076] Wiring board 317 is a plate-like member on which wiring is formed for electrically connecting drive circuit 340 and multiple piezoelectric elements 311. The surface of wiring board 317 facing direction c2 is joined to vibration plate 316 via multiple conductive bumps T. On the other hand, drive circuit 340 is mounted on the surface of wiring board 317 facing direction c1.

[0077] The drive circuit 340 is an IC (Integrated Circuit) chip that outputs a drive signal and a reference voltage for driving each piezoelectric element 311. Specifically, the drive circuit 340 switches whether or not to supply the drive signal Com as a drive pulse PD to each of the plurality of piezoelectric elements 311, based on the control signal SI described above.

[0078] Although not shown, an end of an external wiring electrically connected to the control device 600 is joined to the surface of the wiring board 317 facing the c1 direction. The external wiring is configured with a connecting component such as an FPC (Flexible Printed Circuits) or an FFC (Flexible Flat Cable). Note that the wiring board 317 may be an FPC, an FFC, or the like.

[0079] 1-4. Operation of the three-dimensional object printing device and three-dimensional object printing method Figure 5 is a flowchart showing the flow of a three-dimensional object printing method according to the first embodiment. The three-dimensional object printing method is performed using a three-dimensional object printing apparatus 100. As shown in Figure 5, in the three-dimensional object printing apparatus 100, first, a workpiece W is placed in step S110. At this time, if necessary, an object O is placed in place of or in addition to the workpiece W. The workpiece or object O may be placed manually by a user, or automatically by the operation of the robot 200 in accordance with the program PG1.

[0080] Next, in step S120, workpiece information Da is generated by the data generation unit 614 using CAD data of the workpiece W, etc., as described above. Thereafter, in step S130, point data Dc is generated by the data generation unit 614. At this time, N detection operations MD are performed according to the number of passes. Then, in step S140, N printing operations MP according to the number of passes are performed using the point data Dc generated in step S130.

[0081] Fig. 6 is a flowchart showing the flow of generating the point data Dc shown in Fig. 5. Below, the flow of processing in step S130 shown in Fig. 5 will be explained based on Fig. 6. As shown in Fig. 6, first, a detection operation MD is performed to detect the actual scanning path of the liquid ejection head 310.

[0082] In the detection operation MD, first, in step S131, point data Dc indicating an ideal scanning path as a reference path is generated by the data generation unit 614 based on the workpiece information Da. Next, in step S132, a detection pattern is printed on the workpiece W or object O while the robot 200 is operated using the point data Dc generated in step S131. After that, in step S133, the actual scanning path in step S132 is detected.

[0083] Next, in step S134, point data Dc indicating a corrected path is generated by data generation unit 614 based on the detection result of detection operation MD, i.e., the actual scanning path detected in step S133. Thereafter, a confirmation operation MC is performed.

[0084] In the confirmation operation MC, first, in step S135, the robot 200 is operated using the point data Dc generated in step S134, while a detection pattern is printed on the workpiece W or object O, similar to step S132 described above. Next, in step S136, the actual scanning path in step S135 is detected, similar to step S133 described above. Thereafter, in step S137, it is determined whether the actual scanning path detected in step S136 is the desired scanning path. For example, if the difference between the actual scanning path detected in step S136 and the reference path is within a predetermined range, it is determined that the actual scanning path detected in step S136 is the desired scanning path.

[0085] If the actual scanning path is not the desired scanning path, the process returns to step S134 described above, where the point data Dc is adjusted so that the actual scanning path approaches the reference path, and point data Dc indicating the corrected path is generated again by the data generation unit 614. On the other hand, if the actual scanning path is the desired scanning path, in step S138, it is determined whether or not it is the Nth pass depending on whether or not the number of transitions from step S137 is N.

[0086] If the Nth pass has not been reached, the process returns to step S131, and the same process as described above is performed for the subsequent passes. On the other hand, if the Nth pass has been reached, the process proceeds to step S140 shown in FIG. 5, and printing is performed.

[0087] Note that although the confirmation operation MC can be used to confirm that the route is the desired one, the confirmation operation MC is not an essential operation in the present invention, and it may be omitted as appropriate depending on the required level of print quality, etc., to shorten the time required to adjust the point data. In other words, after generating the point data Dc in step S134, it is also possible to proceed directly to step S138.

[0088] 7 is a diagram for explaining the detection operation MD and the printing operation MP in the first embodiment. Fig. 7 illustrates a case where the number of passes, which is the number of times each of the detection operation MD and the printing operation MP is performed, is two. In the example shown in Fig. 7, the liquid ejection head 310 is scanned in the direction along the Y axis in each operation.

[0089] A first-pass printing operation MP_1 is performed on a first region RP1 of the workpiece W, but prior to this printing, a first-pass detection operation MD_1 is performed on the first region RP1 or a region corresponding thereto. Similarly, a second-pass printing operation MP_2 is performed on a second region RP2 of the workpiece W, but prior to this printing, a second-pass detection operation MD_2 is performed on the second region RP2 or a region corresponding thereto. Here, the first region RP1 and the second region RP2 are shifted in the direction along the X-axis so that they partially overlap. In this embodiment, the first-pass and second-pass detection operations MD are performed sequentially, and then the first-pass and second-pass printing operations MP are performed sequentially. The number of passes may be one, or may be three or more.

[0090] Fig. 8 is a diagram illustrating point data Dc indicating an ideal scanning path. Fig. 8 shows point data Dc_1 indicating a reference path RU_1, which is an ideal scanning path in the first-pass detection operation MD. Note that Fig. 8 also schematically shows multiple nozzles N of the liquid ejection head 310. Also, in Fig. 8, the ideal scanning path is a linear path along the scanning direction DS of the liquid ejection head 310, but the ideal scanning path may have curved or bent portions as necessary.

[0091] In the example shown in FIG. 8, point data Dc_1 is made up of 17 pieces of data: data PS, P1 to P15, and PE. Data PS indicates the start position of the scanning path of liquid ejection head 310. Data PE indicates the end position of the scanning path of liquid ejection head 310. Data P1 to P15 indicate positions between the start position and end position of the scanning path of liquid ejection head 310. Note that the number of pieces of data indicating positions between the start position and end position of the scanning path of liquid ejection head 310 is not limited to the example shown in FIG. 8, and can be any number.

[0092] Fig. 9 is a diagram for explaining detection of a position on an actual scanning path RUa when point data Dc_1 indicating an ideal scanning path is used. Fig. 9 shows a first scanning path RUa_1, which is the actual scanning path RUa in the first-pass detection operation MD. In the first-pass detection operation MD, as shown in Fig. 9, a first detection pattern PT1 is printed as the detection pattern.

[0093] In the example shown in FIG. 9, the first detection pattern PT1 is made up of a plurality of marks M1. The plurality of marks M1 are formed by ejecting ink from each nozzle N at each position indicated by the above-mentioned point data Dc_1. When the first scanning path RUa_1 is an ideal scanning path, the plurality of marks M1 of the first detection pattern PT1 are arranged in a matrix in the X-axis direction and the Y-axis direction. FIG. 9 shows a state in which the first scanning path RUa_1 deviates from the ideal scanning path and meanders in the X-axis direction, resulting in the arrangement of the plurality of marks M1 of the first detection pattern PT1 being distorted in the X-axis direction.

[0094] The first scanning path RUa_1 is detected using imaging information Db obtained by imaging the first detection pattern PT1 with the imaging device 330. The imaging is performed, for example, while the imaging device 330 is scanning together with the liquid ejection head 310 when the first detection pattern PT1 is formed. Note that the imaging may also be performed by the imaging device 330 in a separate scan after the first detection pattern PT1 is formed.

[0095] In FIG. 9, the angle of view AI of the imaging device 330 is indicated by a dashed line. The angle of view AI preferably includes two or more marks M1. When the angle of view AI includes two or more marks M1 at different positions along the Y axis, the deviation along the X axis or the deviation along the Y axis of the actual positions corresponding to two adjacent data pieces among the multiple data pieces represented by the point data Dc_1 can be detected based on the positional relationship of these marks M1. Furthermore, when the angle of view AI includes two or more marks M1 at different positions along the X axis, the orientation around the Y axis can also be detected from the spacing between the marks M1. Furthermore, when the angle of view AI includes two or more marks M1 at different positions along the Y axis and two or more marks M1 at different positions along the X axis, the orientation of the liquid ejection head 310 around the Z axis can also be detected based on the positional relationship of these marks M1.

[0096] Fig. 10 is a diagram for explaining the deviation of the actual scanning path RUa from the ideal scanning path. In Fig. 10, a first scanning path RUa_1, which is the actual scanning path in the first-pass detection operation MD, is shown in comparison with a reference path RU_1.

[0097] Fig. 11 is a diagram illustrating an example of point data Dc_1 corrected based on the actual scanning path RUa. Fig. 11 shows point data Dc_1 corrected using the detection results of the first-pass detection operation MD. The point data Dc_1 generated in the above-mentioned step S134 is obtained by determining a corrected path RC_1 that moves so as to offset the deviation of the first scanning path RUa_1 from the reference path RU_1, as shown in Fig. 11, and correcting the point data Dc_1 to indicate the position of this corrected path RC_1.

[0098] 11, the absolute value of the difference between the reference path RU_1 and the corrected path RC_1 is equal to the absolute value of the difference between the reference path RU_1 and the first scanning path RUa_1. In other words, when the absolute value of the difference between the reference path RU_1 and the corrected path RC_1 is defined as the correction amount obtained by multiplying the absolute value of the difference between the reference path RU_1 and the first scanning path RUa_1 by a coefficient α, α is 1.

[0099] FIG. 12 is a diagram illustrating another example of point data Dc_1 corrected based on the actual scanning path RUa. In the example shown in FIG. 12, the absolute value of the difference between the reference path RU_1 and the corrected path RC_1 is larger than the absolute value of the difference between the reference path RU_1 and the first scanning path RUa_1. In other words, when the absolute value of the difference between the reference path RU_1 and the corrected path RC_1 is set as the correction amount obtained by multiplying the absolute value of the difference between the reference path RU_1 and the first scanning path RUa_1 by a coefficient α, α is larger than 1. In other words, the degree of correction of point data Dc_1 based on the actual scanning path RUa can be set arbitrarily using the coefficient α. Although FIG. 12 shows a case where α is larger than 1, it is also possible to set α to be smaller than 1.

[0100] FIG. 13 is a diagram illustrating an actual scanning path RUb when corrected point data Dc_1 is used. FIG. 13 illustrates a state in which, during confirmation operation MC, the robot 200 is operated using point data Dc_1 corrected based on the detection results of the first-pass detection operation MD, while printing the first detection pattern PT1. Also, FIG. 13 illustrates the corrected path RC_1 shown in FIG. 12 for comparison with the actual scanning path. This actual scanning path corresponds to the second scanning path RUb_1, which is the actual scanning path during the first printing operation MP_1.

[0101] 13, the deviation of the second scanning path RUb_1 from the ideal scanning path is reduced. Detection of the actual scanning path in the checking operation MC is performed in the same manner as detection of the first scanning path RUa_1.

[0102] 14 is a diagram for explaining the detection of the actual scanning path RUa in the subsequent pass, showing the state in which the second detection pattern PT2, which is the detection pattern in the detection operation MD of the second pass, is printed.

[0103] 14, the second detection pattern PT2 is composed of multiple marks M2. Similar to the multiple marks M1 of the first detection pattern PT1 described above, the multiple marks M2 are formed by ejecting ink from each nozzle N at each position indicated by the point data Dc of the second pass. However, the second detection pattern PT2 is positioned offset in the direction along the Y axis relative to the first detection pattern PT1. Therefore, the second detection pattern PT2 can be detected separately from the first detection pattern PT1 from the imaging results of the imaging device 330.

[0104] FIG. 15 is a diagram illustrating the corrected scanning path RUb in the subsequent pass. FIG. 15 shows a state in which, during confirmation operation MC, the robot 200 is operated using point data Dc corrected based on the detection results of the second-pass detection operation MD, while printing the second detection pattern PT2. Also, FIG. 15 illustrates a corrected path RC_2, which is the path indicated by the point data Dc, for comparison with the actual scanning path. The actual scanning path corresponds to the second scanning path RUb_1, which is the actual scanning path during the second printing operation MP_2.

[0105] As described above, the three-dimensional object printing apparatus 100 has the liquid ejection head 310, the robot 200 which is an example of a "movement mechanism," and the detection unit 615. As described above, the liquid ejection head 310 ejects ink, which is an example of a "liquid," onto the three-dimensional workpiece W. The robot 200 changes the position and orientation of the liquid ejection head 310 relative to the workpiece W. The detection unit 615 detects the position of the liquid ejection head 310 relative to the workpiece W or the object O. As described above, the three-dimensional object printing apparatus 100 of this embodiment has the imaging device 330, and the detection unit 615 detects the position of the liquid ejection head 310 relative to the workpiece W or the object O based on the imaging results of the imaging device 330.

[0106] In particular, the three-dimensional object printing apparatus 100 executes a first detection operation MD_1 and a first printing operation MP_1, as described above. In the first detection operation MD_1, the robot 200 causes the liquid ejection head 310 to scan the workpiece W or the object O along a first scanning path RUa_1, while the detection unit 615 detects the position of the liquid ejection head 310 relative to the first scanning path RUa_1. In the first printing operation MP_1, the robot 200 causes the liquid ejection head 310 to scan along a second scanning path RUb_1 based on the detection result by the detection unit 615 in the first detection operation MD_1, while the liquid ejection head 310 ejects ink onto a first region RP1 of the workpiece W.

[0107] In the three-dimensional object printing device 100 described above, the second scanning path RUb_1 is based on the detection result by the detection unit 615 in the first detection operation MD_1. Therefore, the first printing operation MP_1 can be performed using the second scanning path RUb_1, which is obtained by correcting the deviation of the first scanning path RUa_1 relative to the reference path RU_1. Here, if the amount of deviation of the first scanning path RUa_1 relative to the reference path RU_1 is a first amount, the path difference between the first scanning path RUa_1 and the second scanning path RUb_1 is the first path difference. If the amount of deviation is a second amount greater than the first amount, the path difference is the second path difference greater than the first path difference. In other words, the greater the path difference between the first scanning path RUa_1 and the reference path RU_1, the greater the correction amount, and therefore the path difference between the first scanning path RUa_1 and the second scanning path RUb_1. Therefore, the image quality of the print on the first region RP1 of the workpiece W can be improved compared to when the first printing operation MP_1 is performed without performing the first detecting operation MD_1.

[0108] Furthermore, since printing is performed by the first printing operation MP_1 after the first detection operation MD_1, the printing speed can be increased compared to a configuration in which the scanning path is corrected by feedback control while detecting the aforementioned deviation.In contrast, in a configuration in which such feedback control is performed, the printing speed is limited by the control cycle, making it difficult to increase the printing speed.

[0109] It is also possible to improve the print quality for the first region RP1 of the work W without correcting the point data Dc_1 by determining the amount of deviation of the first scanning path RUa_1 from the reference path RU_1, which is the ideal scanning path, from the detection results by the detection unit 615 in the first detection operation MD_1, and correcting the print data Img so that this deviation is offset, or by controlling the nozzles corresponding to the ink ejection to shift in the nozzle row direction so that this deviation is offset. However, in this case, the effective printing width in the b-axis direction in one printing operation must be set narrower than the length of the nozzle row, which reduces printing productivity.

[0110] In the first detection operation MD_1, the liquid ejection head 310 forms a first detection pattern PT1 by ejecting ink onto the workpiece W or object O, and the detection unit 615 detects the first detection pattern PT1 to detect a position relative to the first scanning path RUa_1.

[0111] Here, the first detection pattern PT1 indicates the actual landing position of ink from the liquid ejection head 310 onto the workpiece W or object O. Therefore, by using the first detection pattern PT1, it is possible to detect the deviation of the first scanning path RUa_1 from the reference path RU_1 with higher accuracy than when the position on the first scanning path RUa_1 is detected without actually ejecting ink.

[0112] The three-dimensional object printing apparatus 100 of this embodiment has an imaging device 330. A detection unit 615 detects the position of the liquid ejection head 310 relative to the workpiece W or object O on the scanning path using the imaging results of the imaging device 330.

[0113] In this embodiment, the first detection pattern PT1 includes multiple marks M1 arranged at intervals from one another, and the imaging device 330 captures the first detection pattern PT1 at an angle of view AI that includes two or more of the multiple marks M1. Because two or more marks M1 are included in one captured image, it is easier to detect the positional relationship between the multiple marks M1 with high accuracy compared to, for example, when only one mark M1 is included in one captured image. This detection method has the advantage of easily detecting the deviation of the first scanning path RUa_1 relative to the reference path RU_1 with high accuracy. In particular, detecting the positional relationship between multiple marks M1 that are positioned differently in the scanning direction DS reduces the likelihood of printing defects during the first printing operation MP_1, such as distortion in the printed image in a direction intersecting the scanning direction DS, thereby improving the image quality of the print produced by the first printing operation MP_1.

[0114] As described above, the position of the imaging device 330 relative to the liquid ejection head 310 is fixed. Therefore, the first detection pattern PT1 can be formed and imaged simultaneously in a single scan. As a result, the time required for the first detection operation MD_1 can be shortened compared to when the formation and imaging of the first detection pattern PT1 are performed by separate scans. Furthermore, because the angle of view AI of the imaging device 330 tracks the movement of the liquid ejection head 310 accompanying the formation of the first detection pattern, even with only one imaging device 330, the first detection pattern PT1 can be imaged by the imaging device 330 over the entire scanning direction DS. Therefore, compared to a configuration in which the position of the imaging device 330 is fixed relative to the workpiece W or object O, the configuration of the three-dimensional object printing apparatus 100 can be simplified and the printable area can be expanded. In contrast, in a configuration in which the position of the imaging device 330 is fixed relative to the workpiece W or object O, the formable area or printable area of ​​the first detection pattern PT1 is limited depending on the installation position or number of the imaging devices 330, depending on the imaging range of the imaging device 330.

[0115] The formation and imaging of the first detection pattern PT1 may be performed by separate scans. In this case, the scanning speeds for forming and imaging the first detection pattern PT1 can be made different from each other. This has the advantage of making it easier to improve the accuracy of both the formation and imaging of the first detection pattern PT1.

[0116] As described above, the three-dimensional object printing apparatus 100 further executes a second detecting operation MD_2 and a second printing operation MP_2. In the second detecting operation MD_2, which is performed between the first detecting operation MD_1 and the first printing operation MP_1, the robot 200 causes the liquid ejection head 310 to scan the workpiece W or the object O along a third scanning path RUa_2, while the detection unit 615 detects the position of the liquid ejection head 310 relative to the third scanning path RUa_2. In the second printing operation MP_2, the robot 200 causes the liquid ejection head 310 to scan the workpiece W or the object O along a fourth scanning path RUb_2 based on the detection result by the detection unit 615, while the liquid ejection head 310 ejects ink onto a second region RP2 that partially overlaps the first region RP1 of the workpiece W.

[0117] Here, similar to the relationship between the first scanning path RUa_1 and the second scanning path RUb_1 described above, when the amount of deviation of the third scanning path RUa_2 from the reference path RU_2 is a third amount, the path difference between the third scanning path RUa_2 and the fourth scanning path RUb_2 is the third path difference, and when the amount of deviation is a fourth amount greater than the third amount, the path difference is a fourth path difference greater than the third path difference. Therefore, similar to the printing on the first region RP1 described above, the image quality of the printing on the second region RP2 of the workpiece W can be improved compared to when the second printing operation MP_2 is performed without performing the second detection operation MD_2. Note that the timing of execution of the second printing operation MP_2 may be before or after the first printing operation MP_1, as long as it is after the second detection operation MD_2.

[0118] Furthermore, similar to the first detection pattern PT1 in the first detection operation MD_1 described above, in the second detection operation MD_2, the liquid ejection head 310 ejects ink onto the workpiece W or object O to form a second detection pattern PT2 at a position shifted from the first detection pattern PT1 in the scanning direction DS of the liquid ejection head 310, and the detection unit 615 detects the second detection pattern PT2 to detect the position on the third scanning path RUa_2. Therefore, similar to the case where the first detection pattern PT1 is used, by using the second detection pattern PT2, it is possible to detect the deviation of the third scanning path RUa_2 from the reference path RU_2 with higher accuracy than when the position on the third scanning path RUa_2 is detected without actually ejecting ink.

[0119] Here, the second detection pattern PT2 is not only formed in a different area from the first detection pattern PT1, but is also formed at a position shifted relative to the first detection pattern PT1 in the scanning direction DS of the liquid ejection head 310. This makes it easy to detect the second detection pattern PT2 and distinguish it from the first detection pattern PT1. It is also easy to detect the positional relationship between the first detection pattern PT1 and the second detection pattern PT2.

[0120] In this embodiment, as described above, the first detection pattern PT1 and the second detection pattern PT2 have different shapes or colors, which makes it easier to distinguish the second detection pattern PT2 from the first detection pattern PT1 than when these patterns have the same shape and color.

[0121] Furthermore, the amount of ink used to form the first detection pattern PT1, which is composed of the above-described multiple marks M1, is less than the amount of ink used in the first printing operation MP_1. Therefore, the influence of the first detection pattern PT1 on the print quality in the first printing operation MP_1 is reduced compared to when the amount of ink used to form the first detection pattern PT1 is greater than the amount of ink used in the first printing operation MP_1. Note that the same is true for the second detection pattern PT2, and the influence of the second detection pattern PT2 on the print quality in the second printing operation MP_2 is reduced.

[0122] Furthermore, as described above, the three-dimensional object printing apparatus 100 further executes a confirmation operation MC between the first detection operation MD_1 and the first printing operation MP_1. In the confirmation operation MC, the robot 200 scans the liquid ejection head 310 relative to the workpiece W or object O along a scanning path based on the detection result by the detection unit 615 in the first detection operation MD_1, while the detection unit 615 detects a position relative to that scanning path. Therefore, after confirming in the confirmation operation MC that the second scanning path RUb_1 is the desired path based on the detection result of the detection unit 615, the first printing operation MP_1 can be executed using the second scanning path RUb_1.

[0123] As described above, the robot 200 is an articulated robot connected to the control device 600, an example of a "robot controller," and equipped with the liquid ejection head unit 300, an example of an end effector including the liquid ejection head 310. The robot 200 moves the liquid ejection head unit 300 along a linear path, such as a straight or curved path, by combining the movements of multiple joints 231-236. Even if the robot 200 is given a reference path RU_1, which is an ideal path, as an instruction for the path along which the liquid ejection head 310 should move, various factors, such as machining errors or assembly errors of each arm, mechanical vibration of each arm, eccentricity of the motor or reducer, and rough resolution of the rotary encoder, can cause operational errors at various times in each joint, resulting in the actual path meandering and deviating from the ideal path. Such deviations are difficult to predict in advance. Therefore, when such an articulated robot is used as a movement mechanism, the effects of executing the first detection operation MD_1 and the first printing operation MP_1 are significant. It should be noted that the above-mentioned deviation of the actual path from the ideal scanning path can also occur in moving mechanisms other than articulated robots, that is, mechanisms that can move by combining the movements of multiple moving parts, and performing the first detection operation MD_1 and the first printing operation MP_1 is similarly useful in moving the liquid ejection head 310 along the ideal scanning path.

[0124] As described above, the three-dimensional object printing apparatus 100 further includes a data generation unit 614 that generates point data Dc that indicates positions where the liquid ejection head 310 must pass. The control device 600 controls the driving of the robot 200 based on the point data Dc from the data generation unit 614. Here, the data generation unit 614 generates point data Dc_1 to be used in the first printing operation MP_1 based on the detection result of the detection unit 615 in the first detection operation MD_1.

[0125] Specifically, the data generation unit 614 generates point data Dc_1 to be used in the first printing operation MP_1 by correcting the point data Dc_1 used in the first detection operation MD_1 based on the detection results of the detection unit 615 in the first detection operation MD_1 so that the second scanning path RUb_1 is closer to the reference path RU_1 than the first scanning path RUa_1.

[0126] Here, the data generation unit 614 corrects the point data Dc_1 used in the first detection operation MD_1 based on the detection result of the detection unit 615 in the first detection operation MD_1 so as to shift the position where the liquid ejection head 310 should pass in a direction intersecting the first scanning path P1a. As a result, the second scanning path RUb_1 can be made closer to the reference path RU_1 than the first scanning path RUa_1b.

[0127] As described above, the first detection operation MD_1 uses either the workpiece W or the object O corresponding to the workpiece W. In the first detection operation MD_1, when the robot 200 scans the liquid ejection head 310 and the detection unit 615 detects the object O, the shape of the object O is substantially the same as the shape of the workpiece W, and the object O is replaced with the workpiece W between the first detection operation MD_1 and the first printing operation MP_1. For this reason, the ink ejected in the first detection operation MD_1 does not affect the image quality of the print on the workpiece W in the first printing operation MP_1.

[0128] On the other hand, in the first detection operation MD_1, when the robot 200 scans the liquid ejection head 310 and the detection unit 615 detects the workpiece W, there is an advantage that the time and effort required to replace the object O with the workpiece W as described above is not required.

[0129] 2. Second embodiment 16 is a block diagram showing the electrical configuration of a three-dimensional object printing apparatus 100A according to the second embodiment. The three-dimensional object printing apparatus 100A is similar to the three-dimensional object printing apparatus 100 of the first embodiment described above, except that it has a liquid ejection head unit 300A and a control device 600A instead of the liquid ejection head unit 300 and the control device 600. The liquid ejection head unit 300A is similar to the liquid ejection head unit 300, except that it has a distance sensor 360 instead of the imaging device 330. The control device 600A is similar to the control device 600, except that it uses a program PG2 instead of the program PG1.

[0130] In the control device 600A, the processing circuitry 610 executes the program PG2 stored in the memory circuitry 620, thereby functioning as an information acquisition unit 611, an arm control unit 612, a discharge control unit 613, a data generation unit 614, and a detection unit 615A.

[0131] The detection unit 615A detects the position of the liquid ejection head 310 relative to the workpiece W or object O on the scanning path using measurement information Dd, which is the measurement result of the distance sensor 360.

[0132] FIG. 17 is a diagram illustrating detection of an actual scanning path RUa in the second embodiment. As shown in FIG. 17, the distance sensor 360 is a displacement sensor that measures the distance from a reference plane RF whose position relative to the workpiece W is fixed. In this embodiment, the reference plane RF is illustrated as a plane facing the X2 direction. Here, the detection axis AS of the distance sensor 360 intersects with the reference plane RF. In the example shown in FIG. 17, the detection axis AS faces the X1 direction. Note that the reference plane RF may be the surface of any object whose position relative to the workpiece W is fixed, and may be the surface of the workpiece W or the surface of an object such as a plate material separate from the workpiece W. Furthermore, the direction of the reference plane RF is not limited to the X2 direction and may be arbitrary as long as the position and orientation of the reference plane RF relative to the surface WF of the workpiece W are known in advance.

[0133] The flow of a three-dimensional object printing method using the three-dimensional object printing device 100A will be described. The three-dimensional object printing method basically follows the explanation of the flowcharts in Figures 5 and 6, but unlike the first embodiment, this embodiment does not print the detection pattern in steps S132 and S135.

[0134] In this three-dimensional object printing method, first, a workpiece W is placed as in the first embodiment. At this time, an object O is placed instead of or in addition to the workpiece W, as necessary. The workpiece or object O may be placed manually by a user, or automatically by the operation of the robot 200 in accordance with the program PG2.

[0135] Next, workpiece information Da is generated by the data generation unit 614 using CAD data or the like of the workpiece W. Thereafter, point data Dc is generated by the data generation unit 614. In the process of generating this point data Dc, the data generation unit 614 generates point data Dc that indicates an ideal scanning path as a reference path based on the workpiece information Da.

[0136] Next, a detection operation MD is executed. In the detection operation MD, the robot 200 is operated using point data Dc that indicates an ideal scanning path, and the position of the liquid ejection head 310 relative to the workpiece W or object O on the scanning path is detected using measurement information Dd that is the measurement result of the distance sensor 360, as shown in FIG.

[0137] Next, based on the detection result of the detection operation MD, i.e., the actual scanning path RUa, point data Dc indicating the corrected path is generated by the data generation unit 614. Then, using the point data Dc indicating the corrected path, a printing operation MP is performed on the workpiece W, and an image based on the printing data Img is formed on the surface of the workpiece W.

[0138] In the three-dimensional object printing method using the three-dimensional object printing apparatus 100A, it is also possible to perform N detection operations MD and N printing operations MP according to the number of passes, as in Example 1. Also, as in Example 1, it is possible to perform a confirmation operation MC between the detection operation MD and the printing operation MP.

[0139] As described above, the three-dimensional object printing apparatus 100A of this embodiment further includes a distance sensor 360. The detection unit 615A detects the position of the liquid ejection head 310 relative to the object O along the scanning path using the measurement results of the distance sensor 360. Here, the relative position of the distance sensor 360 relative to the liquid ejection head 310 is fixed. Then, during the first detection operation MD_1, the distance sensor 360 measures the distance between the reference plane RF, on which the relative position of the liquid ejection head 310 relative to the workpiece W is fixed. Therefore, the position of the liquid ejection head 310 along the scanning path can be detected based on the measurement results of the distance sensor 360, even without actually ejecting ink from the liquid ejection head 310. As a result, ink consumption can be reduced compared to the configuration in which a detection pattern is printed as described in the first embodiment. Furthermore, when an object O is not used, the detection pattern can be prevented from affecting the image formed on the workpiece W compared to the configuration in which a detection pattern is printed as described in the first embodiment.

[0140] In this embodiment, in the first detection operation MD_1, the detection axis AS of the distance sensor 360 intersects with the scanning direction DS of the liquid ejection head 310. Therefore, it is possible to detect the position of the liquid ejection head 310 with respect to the scanning path based on the measurement results of the distance sensor 360. In particular, when the detection axis AS of the distance sensor 360 intersects not only with the scanning direction DS of the liquid ejection head 310 but also with the ink ejection direction from the liquid ejection head 310, for example, when the detection axis AS is along the X-axis as in this embodiment, there is an advantage in that it is easier to detect with high accuracy any deviation of the meandering scanning path with respect to the reference path RU_1.

[0141] 3. 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. Two or more embodiments arbitrarily selected from the following examples can be appropriately combined within the scope of not contradicting each other.

[0142] 3-1. 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 present invention is not limited to this configuration. The movement mechanism may be capable of three-dimensionally changing the position and orientation of the liquid ejection head relative to the workpiece. Therefore, 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 movable part of the robot arm is not limited to a rotation mechanism and may be, for example, an extension / retraction mechanism. Alternatively, the mechanism need not be a robot arm as long as it is capable of three-dimensionally changing the position of the liquid ejection head.

[0143] 3-2. Variation 2 In the above-described embodiment, the liquid ejection head is fixed to the tip of the robot arm using screws or the like, but is not limited to this. For example, the liquid ejection head may be fixed to the tip of the robot arm by gripping the liquid ejection head with a gripping mechanism such as a hand attached to the tip of the robot arm.

[0144] 3-3. Variation 3 In addition, in the above-described embodiment, a moving mechanism configured to move the liquid ejection head is exemplified, but the present invention is not limited to this configuration, and for example, the position of the liquid ejection head may be fixed, and the moving mechanism may move the workpiece, thereby changing the position and orientation of the workpiece relative to the liquid ejection head in three dimensions. In this case, for example, the workpiece is gripped by a gripping mechanism such as a hand attached to the tip of a robot arm.

[0145] 3-4. Variation 4 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.

[0146] 3-5. Variation 5 The uses of the three-dimensional printing device of the present invention are not limited to printing. For example, a three-dimensional printing device that ejects a solution of color material is used as a manufacturing device for forming color filters for liquid crystal display devices. Also, a three-dimensional printing device that ejects a solution of conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a three-dimensional printing device can also be used as a jet dispenser that applies liquid such as adhesive to a workpiece. [Explanation of symbols]

[0147] 100...three-dimensional object printing device, 100A...three-dimensional object printing device, 200...robot (movement mechanism), 300...liquid ejection head unit (end effector), 300A...liquid ejection head unit (end effector), 310...liquid ejection head, 330...imaging device, 360...distance sensor, 600...control device (robot controller), 600A...control device (robot controller), 614...data generation unit, 615...detection unit, 615A...detection unit, AI...angle of view, AS...detection axis, DS...scanning direction, Dc...point data, Dc_1...point data, Dc_N...point data, M1...mark, M2...mark, MC...confirmation operation, MD...detection operation, MD_1...first detection operation, MD_2...second detection operation, MD_N...printing operation, MP...printing operation, MP_1...first printing operation, MP_2...second printing operation, MP_N...printing operation, O...object, PT1...first detection pattern, PT2...second detection pattern, RF...reference surface, RP1...first area, RP2...second area, RU_1...reference path, RU_2...reference path, RUa...scanning path, RUa_1...first scanning path, RUa_1b...first scanning path, RUa_2...third scanning path, RUb...scanning path, RUb_1...second scanning path, RUb_2...fourth scanning path, W...work.

Claims

1. a liquid ejection head that ejects liquid onto a three-dimensional workpiece; a robot that changes a relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece; a detection unit that detects a relative position of the liquid ejection head with respect to the workpiece or the object, a first detection operation in which the robot scans the liquid ejection head relative to the workpiece or the object along a first scanning path, and the detection unit detects a position of the liquid ejection head relative to the first scanning path; a first printing operation in which the robot scans the liquid ejection head relative to the workpiece along a second scanning path based on the detection result by the detection unit in the first detection operation, and the liquid ejection head ejects liquid onto a first region of the workpiece; A three-dimensional object printing device characterized by the above.

2. detecting a deviation amount between the first scanning path and a reference path based on a detection result by the detection unit; The three-dimensional object printing device according to claim 1 .

3. detecting a deviation amount between the first scanning path and the reference path in a direction intersecting with the reference path based on a detection result by the detection unit; 3. The three-dimensional object printing device according to claim 2.

4. the second scanning path is a path in which the deviation amount in a direction intersecting the reference path is reduced; 4. The three-dimensional object printing device according to claim 3.

5. a sensor whose position relative to the liquid ejection head is fixed; the detection unit detects the relative position of the liquid ejection head with respect to the workpiece or the object using the measurement result of the sensor in the first detection operation. The three-dimensional object printing device according to any one of claims 1 to 4.

6. In the first detection operation, a detection axis of the sensor intersects with a scanning direction of the liquid ejection head.

6. The three-dimensional object printing device according to claim 5.

7. the liquid ejection head does not eject liquid in the first detection operation; 7. The three-dimensional object printing device according to claim 5 or 6.

8. In the first detection operation, the liquid ejection head ejects liquid onto the workpiece or the object to form a first detection pattern, and the detection unit detects the first detection pattern to detect a position on the first scanning path. The three-dimensional object printing device according to claim 1 or 4 .

9. further comprising an imaging device; the detection unit detects a position of the liquid ejection head relative to the workpiece or the object in relation to a scanning path using an imaging result of the imaging device; the first detection pattern includes a plurality of marks arranged at intervals from one another; the imaging device images the first detection pattern at an angle of view that includes two or more of the plurality of marks; The three-dimensional object printing device according to claim 8 .

10. Between the first detection operation and the first printing operation, the robot scans the liquid ejection head relative to the workpiece or the object along a scanning path based on the detection result by the detection unit in the first detection operation, and the detection unit further performs a confirmation operation to detect a position relative to the scanning path. The three-dimensional object printing device according to any one of claims 1 to 9.

11. a second detection operation in which, between the first detection operation and the first printing operation, the robot scans the liquid ejection head relative to the workpiece or the object along a third scanning path, and the detection unit detects a position relative to the third scanning path; and further performing a second printing operation in which the robot scans the liquid ejection head relative to the workpiece along a fourth scanning path based on the detection result by the detection unit, and the liquid ejection head ejects liquid onto a second area of ​​the workpiece that partially overlaps the first area. The three-dimensional object printing device according to any one of claims 1 to 10.

12. a control unit that controls the robot; a data generating unit that generates point data indicating a position where the liquid ejection head should pass; the control unit controls driving of the robot based on the point data from the data generation unit, the data generation unit generates point data to be used in the first printing operation based on a detection result of the detection unit in the first detection operation. The three-dimensional object printing device according to any one of claims 1 to 11.

13. the data generation unit generates point data to be used in the first printing operation by correcting the point data used in the first detection operation based on the detection result of the detection unit in the first detection operation. The three-dimensional object printing device according to claim 12 .

14. the data generation unit corrects the point data used in the first detection operation based on the detection result of the detection unit in the first detection operation so as to shift a position at which the liquid ejection head should pass in a direction intersecting the first scanning path. The three-dimensional object printing device according to claim 13 .

15. A three-dimensional object printing method for printing on a three-dimensional workpiece using a liquid ejection head that ejects liquid onto the workpiece and a robot that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, a first detection operation in which the robot detects a position of the liquid ejection head relative to the workpiece or the object along a first scanning path while scanning the liquid ejection head along the first scanning path; a first printing operation in which the liquid ejection head ejects liquid onto a first region of the workpiece while the robot scans the liquid ejection head relative to the workpiece along a second scanning path based on the detection result of the first detection operation; A three-dimensional object printing method.

Images