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

Abstract

The present invention provides a three-dimensional object printing apparatus and a three-dimensional object printing method for improving the print quality of a three-dimensional workpiece. The three-dimensional object printing apparatus includes: a liquid ejection head that ejects a liquid onto the three-dimensional workpiece; a moving mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece; 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, while the moving mechanism scans the liquid ejection head along a first scan path with respect to the workpiece or the object, the detection unit detects a position related to the first scan path, and a first printing operation in which, while the moving mechanism scans the liquid ejection head along a second scan path based on the detection result detected by the detection unit in the first detection operation, the liquid ejection head ejects the liquid onto a first region of the workpiece.

Description

Technical Field

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

[0002] There is known a three-dimensional object printing apparatus that moves an inkjet print head by a combination of operations of a plurality of movable parts and prints on the surface of a three-dimensional object by an inkjet method. For example, the apparatus described in Patent Document 1 includes: a robotic arm having a plurality of movable parts; an inkjet print head mounted at the tip of the robotic arm; and a controller that controls the operation of the robotic arm. Here, the controller controls the operation of the robotic arm such that the inkjet print head follows a series of scanning paths.

[0003] When the inkjet print head linearly moves along a scanning path by a combination of operations of a plurality of movable parts, the following problem may occur. Even if only an ideal path is given as an indication of the path along which the inkjet print head should move, operation errors of each joint part occur at various timings in the middle of the scanning path, so there is a problem that the actual path deviates from the ideal path like a meandering line and the print quality deteriorates.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-111307 Summary of the Invention

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

[0006] Another aspect of the three-dimensional object printing apparatus according to the present invention includes: a liquid ejection head that ejects liquid onto a three-dimensional workpiece; a moving 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 and a first printing operation. The first detection operation is an operation in which, while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece or the object along a first scan path, the detection unit detects a position related to the first scan path. The first printing operation is an operation in which, while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece along a second scan path, the liquid ejection head ejects liquid onto a first region of the workpiece. When the offset amount of the first scan path with respect to a reference path is a first amount, the path difference between the first scan path and the second scan path is a first path difference. When the offset amount 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 according to the present invention is a three-dimensional object printing method in which a liquid ejection head that ejects liquid onto a three-dimensional workpiece and a moving mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece are used to print the workpiece. In the three-dimensional object printing method, a first detection operation and a first printing operation are performed. The first detection operation is an operation in which, while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece or the object along a first scan path, a position related to the first scan path is detected. The first printing operation is an operation in which, while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece along a second scan path based on the detection result in the first detection operation, the liquid ejection head ejects liquid onto a first region of the workpiece.

[0008] Another aspect of the three-dimensional object printing method according to the present invention is a three-dimensional object printing method for printing a three-dimensional workpiece by using a liquid ejection head that ejects a liquid onto the three-dimensional workpiece and a moving mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece. In the three-dimensional object printing method, a first detection operation and a first printing operation are performed. The first detection operation is an operation of detecting a position related to the first scanning path while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece or the object along the first scanning path. The first printing operation is an operation in which the liquid ejection head ejects the liquid onto a first area of the workpiece while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece along the second scanning path. When the offset amount of the first scanning path with respect to the reference path is a first amount, the path difference between the first scanning path and the second scanning path is a first path difference. When the offset 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 DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A perspective view showing an outline of a three-dimensional object printing apparatus according to the first embodiment.

[0010] Figure 2 A block diagram showing an electrical configuration of a three-dimensional object printing apparatus according to the first embodiment.

[0011] Figure 3 A perspective view showing a schematic configuration of a liquid ejection head unit in the first embodiment.

[0012] Figure 4 A cross-sectional view showing a structural example of a liquid ejection head in the first embodiment.

[0013] Figure 5 A flowchart showing a process of a three-dimensional object printing method according to the first embodiment.

[0014] Figure 6 For showing Figure 5 A flowchart showing a process of generating the point data shown.

[0015] Figure 7 A diagram for explaining the detection operation and the printing operation in the first embodiment.

[0016] Figure 8 A diagram for explaining point data representing an ideal scanning path.

[0017] Figure 9A diagram for explaining the detection of positions related to an actual scanning path in a case where point data representing an ideal scanning path is used.

[0018] Figure 10 A diagram for explaining the offset of an actual scanning path relative to an ideal scanning path.

[0019] Figure 11 A diagram for showing an example of point data corrected based on an actual scanning path.

[0020] Figure 12 A diagram for explaining another example of point data corrected based on an actual scanning path.

[0021] Figure 13 A diagram for explaining an actual scanning path in a case where corrected point data is used.

[0022] Figure 14 A diagram for explaining the detection of an actual scanning path in a subsequent cycle.

[0023] Figure 15 A diagram for explaining a corrected scanning path in a subsequent cycle.

[0024] Figure 16 A block diagram showing the electrical structure of a three-dimensional object printing apparatus according to the second embodiment.

[0025] Figure 17 A diagram for explaining the detection of an actual scanning path in the second embodiment. Detailed Embodiment

[0026] Hereinafter, while referring to the accompanying drawings, preferred embodiments of the present invention will be described. In the drawings, the dimensions or scales of each part are appropriately different from the actual ones, and there are also parts schematically shown for easy understanding. In addition, the scope of the present invention is not limited to these embodiments as long as there is no description in the following explanation that particularly limits the present invention.

[0027] The following description will be appropriately made using the mutually intersecting X-axis, Y-axis, and Z-axis. In addition, one direction along the X-axis is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. Similarly, the directions opposite to each other along the Y-axis are referred to as the Y1 direction and the Y2 direction. In addition, the directions opposite to each other along the Z-axis are referred to as the Z1 direction and the Z2 direction.

[0028] Here, the X-axis, Y-axis, and Z-axis are the coordinate axes of a basic coordinate system set in the space where the workpiece W and the base 210 described later are provided. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. Additionally, the Z-axis may not be a vertical axis. Furthermore, although the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, they are not limited thereto, and there are cases where they are not orthogonal. For example, it is sufficient that the X-axis, Y-axis, and Z-axis intersect at angles within the range of 80° or more and 100° or less.

[0029] 1. First Embodiment

[0030] 1-1. Outline of the Three-Dimensional Object Printing Device

[0031] Figure 1 FIG. is a perspective view showing an outline of the three-dimensional object printing device 100 according to the first embodiment. The three-dimensional object printing device 100 is a device that prints on the surface of a three-dimensional workpiece W by an inkjet method.

[0032] The workpiece W has a surface WF to be printed. In Figure 1 the example shown, the workpiece W is a rectangular parallelepiped, and the surface WF is a plane facing the Z1 direction. Additionally, the printing object may also be a surface other than the surface WF among the multiple surfaces of the workpiece W. Furthermore, the size, shape, or setting attitude of the workpiece W is not limited to Figure 1 the example shown, and it is arbitrary.

[0033] Here, in the detection operation MD described later, an object O corresponding to the workpiece W is used as needed. The object O is an object having a surface OF with a shape and attitude substantially the same as the surface WF. For example, the object O is an object having a shape substantially the same as the workpiece W and is set in a posture substantially the same as the workpiece W instead of the workpiece W. Additionally, the object O may also be a thin film that is adhesively attached to the surface WF of the workpiece W in a peelable manner. In this thin film, a receiving layer for easily absorbing ink is provided as needed.

[0034] In Figure 1 the example shown, the three-dimensional object printing device 100 is an inkjet printer using a vertical articulated robot. Specifically, as Figure 1 shown, the three-dimensional object printing device 100 includes a robot 200, a liquid ejection head unit 300, a liquid reservoir 400, a supply flow path 500, and a control device 600. Hereinafter, first, each part of the three-dimensional object printing device 100 will be briefly described in sequence.

[0035] The robot 200 is an example of a moving mechanism that changes the position and attitude of the liquid ejection head unit 300 relative to the workpiece W. In Figure 1In the illustrated example, the robot 200 is a so-called six-axis vertical articulated robot. Specifically, the robot 200 has a base 210 and an arm 220.

[0036] The base 210 is a seat that supports the arm 220. Figure 1 In the illustrated example, the base 210 is fixed to a setting surface such as a floor surface facing the Z1 direction by means of screw fixation or the like. In addition, the setting surface to which the base 210 is fixed may be a surface facing any direction, and is not limited to Figure 1 the illustrated example, and may be, for example, a surface of a wall, a ceiling, a surface of a movable cart, or the like.

[0037] The arm 220 is a six-axis robotic arm having a proximal end mounted on the base 210 and a distal end that three-dimensionally changes its position and orientation relative to the proximal end. Specifically, the arm 220 has arms 221, 222, 223, 224, 225, and 226, and these arms are connected in sequence.

[0038] The arm 221 is connected to the base 210 via a joint portion 231 so as to be rotatable about a first rotation axis O1. The arm 222 is connected to the arm 221 via a joint portion 232 so as to be rotatable about a second rotation axis O2. The arm 223 is connected to the arm 222 via a joint portion 233 so as to be rotatable about a third rotation axis O3. The arm 224 is connected to the arm 223 via a joint portion 234 so as to be rotatable about a fourth rotation axis O4. The arm 225 is connected to the arm 224 via a joint portion 235 so as to be rotatable about a fifth rotation axis O5. The arm 226 is connected to the arm 225 via a joint portion 236 so as to be rotatable about a sixth rotation axis O6.

[0039] In Figure 1 the illustrated example, the joint portions 231 to 236 are respectively mechanisms that rotatably connect one of the two adjacent arms to the other. Although not shown, in each of the joint portions 231 to 236, a drive mechanism is provided that rotates one of the two adjacent arms relative to the other. This drive mechanism has, for example, a motor that generates a driving force for this rotation, a speed reducer that decelerates and outputs this driving force, and an encoder such as a rotary encoder that detects the angle of this rotation. In addition, this drive mechanism corresponds to the Figure 2 illustrated arm drive mechanism 230 described later.

[0040] The first rotation axis O1 is an axis perpendicular to a setup 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.

[0041] In addition, for these rotation axes, the so-called "perpendicular" includes not only the case where the angle formed by two rotation axes is strictly 90°, but also the case where the angle formed by two rotation axes deviates within a range of ±5° from 90°. Similarly, the so-called "parallel" includes not only the case where two rotation axes are strictly parallel, but also the case where one of the two rotation axes is inclined within a range of ±5° with respect to the other.

[0042] At the tip of the above-mentioned arm 221, that is, in the arm 226, a liquid ejection head unit 300 is installed as an end effector.

[0043] 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 the present embodiment, the liquid ejection head unit 300 has, in addition to the liquid ejection head 310, a pressure regulating valve 320 that regulates 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. Since these devices are fixed to the arm 226, the positional and postural relationships between them are fixed.

[0044] The liquid ejection head 310 will be described later. The pressure regulating valve 320 is a valve mechanism that opens and closes according to the pressure of the ink in the liquid ejection head 310. By this opening and closing, the pressure of the ink in the liquid ejection head 310 is maintained as a negative pressure within a predetermined range. Therefore, the stabilization of the meniscus of the ink formed in the nozzle N of the liquid ejection head 310 is achieved. As a result, the entry of air bubbles into the nozzle N or the overflow of ink from the nozzle N can be prevented.

[0045] In addition, although in Figure 1 the example shown, the respective numbers of the liquid ejection head 310 and the pressure regulating valve 320 included in the liquid ejection head unit 300 are one, the number is not limited to Figure 1 the example shown, and may be two or more. In addition, the installation positions of the pressure regulating valve 320 and the imaging device 330 are not limited to the arm 226. For example, they may be other arms or the like, or may be positions fixed to the base 210.

[0046] 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 also include a zoom lens or a focusing lens, etc. The imaging element is a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary MOS) image sensor, or the like.

[0047] The liquid storage unit 400 is a container for storing ink. The liquid storage unit 400 is, for example, a bag-shaped ink bag formed of a flexible film. The ink stored in the liquid storage unit 400 is, for example, ink containing a color material such as a dye or a pigment. In addition, the type of ink stored in the liquid storage unit 400 is not limited to ink containing a color material. For example, it may also be ink containing a conductive material such as metal powder. Furthermore, the ink may have a curability such as ultraviolet curability. In the case where the ink has a curability such as ultraviolet curability, for example, an ultraviolet irradiation mechanism is mounted on the liquid ejection head unit 300.

[0048] In Figure 1 In the example shown, the liquid storage unit 400 is fixed to a wall, a ceiling, a pillar, or the like in such a manner that it is always located in a position in the Z1 direction relative to the liquid ejection head 310. That is, the liquid storage unit 400 is located above the liquid ejection head 310 in the vertical direction relative to the moving area of the liquid ejection head 310. Therefore, even without using a mechanism such as a pump, ink can be supplied from the liquid storage unit 400 to the liquid ejection head 310 with a predetermined pressure.

[0049] In addition, the installation location of the liquid storage unit 400 only needs to be able to supply ink from the liquid storage unit 400 to the liquid ejection head 310 with a predetermined pressure, and it may also be located below the liquid ejection head 310 in the vertically upward direction. In this case, for example, it is only necessary to use a pump to supply ink from the liquid storage unit 400 to the liquid ejection head 310 with a predetermined pressure.

[0050] The supply flow path 500 is a flow path for supplying ink from the liquid storage unit 400 to the liquid ejection head 310. A pressure regulating valve 320 is provided in the middle of the supply flow path 500. Therefore, even if the positional relationship between the liquid ejection head 310 and the liquid storage unit 400 changes, the pressure fluctuation of the ink in the liquid ejection head 310 can be reduced.

[0051] The supply flow path 500 is divided into an upstream flow path 510 and a downstream flow path 520 by the pressure regulating valve 320. That is, the supply flow path 500 has an upstream flow path 510 that connects the liquid storage unit 400 and the pressure regulating valve 320, and a downstream flow path 520 that connects the pressure regulating valve 320 and the liquid ejection head 310.

[0052] The upstream flow path 510 and the downstream flow path 520 are each constituted by, for example, the internal space of a tube body. Here, the tube body used in the upstream flow path 510 is made of an elastic material such as a rubber material or an elastomer material, and has flexibility. In this way, by using a flexible tube body to constitute the upstream flow path 510, changes in the relative positional relationship between the liquid storage unit 400 and the pressure regulating valve 320 can be tolerated. Therefore, even if the position or posture of the liquid ejection head 310 changes while the position and posture of the liquid storage unit 400 are fixed, ink can be supplied from the liquid storage unit 400 to the pressure regulating valve 320. On the other hand, the tube body used in the downstream flow path 520 may not have flexibility. Therefore, the tube body used in 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 rigid material such as a resin material.

[0053] In addition, a part of the upstream flow path 510 may also be constituted by a non-flexible component. Furthermore, the downstream flow path 520 is not limited to a structure using a tube body. For example, a part or all of the downstream flow path 520 may have a structure of a distribution flow path that distributes the ink from the pressure regulating valve 320 to multiple places, or may be integrally formed with the liquid ejection head 310 or the pressure regulating valve 320.

[0054] The control device 600 is a device that controls the driving of each part of the three-dimensional object printing device 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 together with the following description of the electrical structure of the three-dimensional object printing device 100.

[0055] 1-2. Electrical Structure of Three-Dimensional Object Printing Device

[0056] Figure 2 is a block diagram showing the electrical structure of the three-dimensional object printing device 100 according to the first embodiment. In Figure 2 shows the electrical structure elements among the structural elements of the three-dimensional object printing device 100. As Figure 2 shown, the control device 600 has a processing circuit 610, a storage circuit 620, a power supply circuit 630, and a drive signal generation circuit 640.

[0057] In addition, the hardware structure included in the control device 600 described below can also be appropriately divided. For example, there is also a case where the arm control unit 612 and the drive signal generation circuit 640 of the control device 600 are independently provided in different hardware structures. In addition, a part or all of the functions of the control device 600 can be implemented by an external device 700 connected to the control device 600, or can also be implemented by other external devices 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.

[0058] The processing circuit 610 has a function of controlling the operations of each part of the three-dimensional object printing device 100 and a function of processing various data. The processing circuit 610 includes, for example, one or more processors such as a CPU (Central Processing Unit). In addition, the processing circuit 610 can also include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU.

[0059] The storage circuit 620 stores various programs such as the program PG1 executed by the processing circuit 610, various data such as the workpiece information Da, the imaging information Db, and the point data Dc processed by the processing circuit 610. The storage circuit 620 includes, for example, a semiconductor memory that is one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). In addition, the storage circuit 620 can also be configured as a part of the processing circuit 610.

[0060] The workpiece information Da represents information on the position and shape of the surface WF of the workpiece W. The workpiece information Da is, for example, information that establishes a correspondence relationship between information such as CAD (computer-aided design) data representing the three-dimensional shape of the workpiece W and the aforementioned basic coordinate system. Here, since the object O corresponds to the workpiece W as described above, it can also be said that the workpiece information Da represents information on the position and shape of the surface OF of the object O. In addition, the workpiece information Da is generated by a data generation unit 614 described later. Furthermore, information representing the three-dimensional shape of the workpiece W is included in the print data Img, for example, or is input from an external device 700 to the control device 600 independently of the print data Img.

[0061] The imaging information Db represents information on the imaging result of the imaging device 330. The imaging information Db represents, for example, the brightness of each coordinate value in the camera coordinate system set in the imaging device 330. In addition, the relationship between this camera coordinate system and the aforementioned basic coordinate system may be established in advance through calibration or may not be established.

[0062] The point data Dc represents information on the position through which the liquid ejection head 310 should pass. The point data Dc represents, for example, the scanning path of the liquid ejection head 310 relative to the workpiece W or the object O in terms of the coordinate values of the basic coordinate system. In addition, the point data Dc is generated by a data generation unit 614 described later.

[0063] The power supply circuit 630 receives power supply from a commercial power supply (not shown) and generates various predetermined potentials. The generated various potentials are appropriately supplied to each part of the three-dimensional object printing apparatus 100. For example, the power supply circuit 630 generates a power supply potential VHV and a bias potential VBS. The bias potential VBS is supplied to the liquid ejection head unit 300. In addition, the power supply potential VHV is supplied to the drive signal generation circuit 640.

[0064] The drive signal generation circuit 640 is a circuit that generates a drive signal Com for driving each piezoelectric element 311 included in the liquid ejection head 310. Specifically, the drive signal generation circuit 640 has, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 640, the DA conversion circuit converts the waveform specification signal dCom (described later) from the processing circuit 610 from a digital signal to an analog signal, and the amplification circuit amplifies this analog signal using the power supply potential VHV from the power supply circuit 630 to generate the drive signal Com. Here, the signal of the waveform actually supplied to the piezoelectric element 311 among the waveforms included in the drive signal Com is the 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 for driving the piezoelectric element 311. The drive circuit 340 switches whether to supply at least a part of the waveforms included in the drive signal Com as the drive pulse PD based on a control signal SI (described later).

[0065] In the control device 600 described above, the processing circuit 610 controls the operations of the respective parts of the three-dimensional object printing device 100 by executing a program PG1 stored in the storage circuit 620. Specifically, by executing the program PG1, the processing circuit 610 functions as an information acquisition unit 611, an arm control unit 612, an ejection control unit 613, a data generation unit 614, and a detection unit 615.

[0066] The information acquisition unit 611 acquires various information required for driving the robot 200 and the liquid ejection head unit 300. Specifically, the information acquisition unit 611 acquires printing data Img from an external device 700, information D1 from an encoder included in the arm drive mechanism 230, shooting information Db from the imaging device 300, workpiece information Da from the storage circuit 620, point data Dc, and other information. In addition, the information acquisition unit 611 appropriately stores the acquired various information in the storage circuit 620.

[0067] The arm control unit 612 controls the drive 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 drive of the motor included in the arm drive mechanism 230 so that the liquid ejection head 310 assumes a desired position and posture.

[0068] In addition, the correspondence between the information D1 and the position and attitude of the liquid ejection head is previously obtained through calibration or the like and stored in the storage circuit 620. Further, the arm control unit 612 obtains information related to the actual position and attitude of the liquid ejection head 310 based on the actual information D1 from the arm drive mechanism 230 and the correspondence. On this basis, the arm control unit 612 performs control using the information related to the position and attitude to make the liquid ejection head 310 have a desired position and attitude. In addition, the arm control unit 612 may 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.

[0069] Based on the information from the information acquisition unit 611, the ejection control unit 613 controls the driving of the liquid ejection head unit 300. 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 operation state of a piezoelectric element 311 (described later) provided in the liquid ejection head 310. Here, other signals such as a timing signal for prescribing the driving timing of the piezoelectric element 311 may be included in the control signal SI. The timing signal is generated, for example, based on the information D1 from an encoder included in the arm drive mechanism 230. The waveform designation signal dCom is a digital signal for prescribing the waveform of the drive signal Com. The print data Img is information representing a two-dimensional or three-dimensional image and is supplied by an external device 700 such as a personal computer.

[0070] The drive control of the liquid ejection head 310 performed by the ejection control unit 613 as described above is performed in synchronization with the drive control of the robot 200 performed by the arm control unit 612 described above. Here, while the robot 200 scans the liquid ejection head 310 in a predetermined direction with respect to the surface WF, ink is ejected from the liquid ejection head 310, thereby printing an image formed of ink on the surface WF of the workpiece W.

[0071] The data generation unit 614 generates dot data Dc. Although it will be described in detail later, the data generation unit 614 generates workpiece information Da, and after generating dot data Dc representing an ideal scanning path based on the workpiece information Da, corrects the dot data Dc representing the ideal scanning path based on the detection result of the detection unit 615. This ideal scanning path corresponds to, for example, the reference paths RU_1 and RU_2 described later. Here, as described above, the generation of the workpiece information Da is implemented by using a sensor or a camera (not shown) calibrated in the aforementioned basic coordinate system to identify the workpiece W and establishing a correspondence between the information representing the three-dimensional shape of the workpiece W and the aforementioned basic coordinate system.

[0072] 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 prior to the subsequent printing operation MP for printing the image based on the printing data Img, and is implemented by a subsequent detection operation MD for detecting the actual scanning path of the liquid ejection head 310. Although it will be described in detail later, the detection unit 615 of the present embodiment uses the shooting result of the imaging device 330 to detect the position related to the actual scanning path of the liquid ejection head 310 with respect to the workpiece W or the object O. Here, in the detection operation MD of the present embodiment, after driving the robot 200 using the aforementioned dot data Dc representing the ideal scanning path and printing a detection pattern on the workpiece W or the object O, the imaging device 330 shoots the detection pattern and uses the shooting result to detect the position related to the scanning path.

[0073] In addition, the image based on the printing data Img is formed by N (N is a natural number of 1 or more) printing operations MP representing the number of cycles. The detection operation MD is performed N times corresponding to the number of times of the printing operation MP. Hereinafter, the printing operation MP in the first cycle is denoted as "printing operation MP_N", and the detection operation MD in the Nth cycle is denoted as "printing operation MD_N". Here, the printing operation MP in the first cycle is the first printing operation MP_1. The printing operation MP in the second cycle is the second printing operation MP_2. The detection operation MD in the first cycle is the first detection operation MD_1. The detection operation MD in the second cycle is the second detection operation MD_2. In addition, hereinafter, the dot data Dc used in the Nth cycle is sometimes denoted as dot data Dc_N.

[0074] 1-3. Liquid ejection head unit

[0075] Figure 3 FIG. is a perspective view showing a schematic structure of the liquid ejection head unit 300 in the embodiment.

[0076] The following description is made using the appropriately intersecting a-axis, b-axis, and c-axis. In addition, one direction along the a-axis is referred to as the a1 direction, and the direction opposite to the a1 direction is referred to as the a2 direction. Similarly, the directions opposite to each other along the b-axis are referred to as the b1 direction and the b2 direction. In addition, the directions opposite to each other along the c-axis are referred to as the c1 direction and the c2 direction.

[0077] Here, the a-axis, b-axis, and c-axis are the coordinate axes of the tool coordinate system set in the liquid ejection head unit 300, and the relative positions and postures with respect to the aforementioned X-axis, Y-axis, and Z-axis change due to the operation of the aforementioned robot 200. Figure 3 In the example shown, the c-axis is a shaft parallel to the aforementioned sixth rotation axis O6. In addition, although the a-axis, b-axis, and c-axis are typically orthogonal to each other, they are not limited thereto. For example, they may intersect at an angle within a range of 80° or more and 100° or less.

[0078] As described above, the liquid ejection head unit 300 includes a liquid ejection head 310, a pressure regulating valve 320, and an imaging device 330. These devices are Figure 3 supported by a support body 350 indicated by the double-dashed line in the figure.

[0079] The support body 350 is made of, for example, a metal material or the like and is a substantially rigid body. In addition, although in Figure 3 the figure, the support body 350 has a flat box shape, the shape of the support body 350 is not particularly limited and is arbitrary.

[0080] The above support body 350 is mounted on the tip of the aforementioned arm 220, that is, on the arm 226. Therefore, the liquid ejection head 310, the pressure regulating valve 320, and the imaging device 330 are respectively fixed to the arm 226.

[0081] In Figure 3 the example shown, the pressure regulating valve 320 is located in the c1 direction with respect to the liquid ejection head 310. The imaging device 330 is located in the a2 direction with respect to the liquid ejection head 310.

[0082] In addition, in Figure 3 the example shown, a part of the downstream flow path 520 of the supply flow path 500 is constituted by a flow path member 521. The flow path member 521 has a flow path for distributing the ink from the pressure regulating valve 320 to a plurality of places of the liquid ejection head 310. The flow path member 521 is, for example, a laminate of a plurality of substrates made of a resin material, and grooves or holes for the ink flow path are appropriately provided on each substrate.

[0083] The liquid ejection head 310 has a nozzle surface F and a plurality of nozzles N that open on the nozzle surface F. InFigure 3 In the illustrated example, 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 side by side at intervals in the direction along the a axis. The first nozzle row L1 and the second nozzle row L2 are each a set of a plurality of nozzles N arranged linearly in the direction along the b axis. Here, the elements associated with the respective nozzles N in the first nozzle row L1 and the elements associated with the respective nozzles N in the second nozzle row L2 in the liquid ejection head 310 have a structure that is substantially symmetric with each other in the direction along the a axis.

[0084] However, the positions of the plurality of nozzles N in the first nozzle row L1 and the plurality of nozzles N in the second nozzle row L2 in the direction along the b axis may be the same as or different from each other. In addition, the elements associated with the respective nozzles N in one of the first nozzle row L1 and the second nozzle row L2 may be omitted. Hereinafter, a structure in which the positions of the plurality of nozzles N in the first nozzle row L1 and the plurality of nozzles N in the second nozzle row L2 in the direction along the b axis are the same as each other is illustrated.

[0085] Figure 4 FIG. is a cross-sectional view showing a structural example of the liquid ejection head 310 in the embodiment. As Figure 4 shown, the liquid ejection head 310 includes a flow channel substrate 312, a pressure chamber substrate 313, a nozzle plate 314, a vibration absorber 315, a diaphragm 316, a plurality of piezoelectric elements 311, a wiring substrate 317, and a housing portion 318.

[0086] The flow channel substrate 312 and the pressure chamber substrate 313 form flow channels for supplying ink to the plurality of nozzles N. The flow channel substrate 312 and the pressure chamber substrate 313 are sequentially laminated in the c1 direction. The flow channel substrate 312 and the pressure chamber substrate 313 are each a plate-like member that is long in the direction along the b axis. The flow channel substrate 312 and the pressure chamber substrate 313 are joined to each other by an adhesive, for example.

[0087] In a region located in a position closer to the c1 direction than the pressure chamber substrate 313, a diaphragm 316, a wiring substrate 317, a housing portion 318, and a drive circuit 340 are provided. On the other hand, in a region located in a position closer to the c2 direction than the flow channel substrate 312, a nozzle plate 314 and a vibration absorber 315 are provided. Generally speaking, these respective elements are plate-like members that are long in the direction along the b axis in the same manner as the flow channel substrate 312 and the pressure chamber substrate 313, and are joined to each other by an adhesive, for example.

[0088] The nozzle plate 314 is a plate-like member formed with a plurality of nozzles N. Each of the plurality of nozzles N is a circular through-hole for ink to pass through. The nozzle plate 314 is manufactured, for example, by processing a single-crystalline silicon substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, in the manufacture of the nozzle plate 314, other known methods and materials can also be appropriately used.

[0089] Here, the aforementioned nozzle surface F is a surface that constitutes the outer shape of the liquid ejection head 310 and extends in a direction perpendicular to the c-axis from the opening at one end of the nozzle N in the c2 direction. Figure 4 In the illustrated example, 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.

[0090] In the flow channel substrate 312, a space Ra, a plurality of supply channels 312a, a plurality of communication channels 312b, and a supply liquid chamber 312c are provided for each of the first nozzle row L1 and the second nozzle row L2. When viewed from above in the direction along the c-axis, the space Ra is a long and narrow opening extending in the direction along the b-axis. The supply channels 312a and the communication channels 312b are each through-holes formed for each nozzle N. The supply liquid chamber 312c is a long and narrow space extending in the direction along the b-axis across a plurality of nozzles N and communicates the space Ra and the plurality of supply channels 312a with each other. Each of the plurality of communication channels 312b overlaps with one nozzle N corresponding to the communication channel 312b when viewed from above.

[0091] The pressure chamber substrate 313 is a plate-like member formed with a plurality of pressure chambers Cv, which are called cavities, for each of the first nozzle row L1 and the second nozzle row L2. The plurality of pressure chambers Cv are arranged in the direction along the b-axis. Each pressure chamber Cv is a long and narrow space formed for each nozzle N and extending in the direction along the a-axis when viewed from above. The flow channel substrate 312 and the pressure chamber substrate 313 are each manufactured, like the aforementioned nozzle plate 314, by processing a single-crystalline silicon substrate using semiconductor manufacturing techniques. However, in the manufacture of each of the flow channel substrate 312 and the pressure chamber substrate 313, other known methods and materials can also be appropriately used.

[0092] The pressure chamber Cv is a space located between the flow channel substrate 312 and the vibration plate 316. For each of the first nozzle array L1 and the second nozzle array L2, a plurality of pressure chambers Cv are arranged in the direction along the b-axis. In addition, the pressure chamber Cv is communicated with the communication flow channel 312b and the supply flow channel 312a, respectively. Therefore, the pressure chamber Cv is communicated with the nozzle N via the communication flow channel 312b, and is communicated with the space Ra via the supply flow channel 312a and the supply liquid chamber 312c.

[0093] A vibration plate 316 is disposed on the surface of the pressure chamber substrate 313 facing the c1 direction. The vibration plate 316 is a plate-shaped member that can vibrate elastically. The vibration plate 316 has, for example, an elastic film composed of silicon oxide (SiO2) and an insulating film composed of zirconium oxide (ZrO2), and these films are stacked together. The elastic film is formed, for example, by thermally oxidizing one surface of a single crystal silicon substrate. The insulating film is formed, for example, by forming a zirconium layer by sputtering and thermally oxidizing the layer.

[0094] On the surface of the vibration plate 316 facing the c1 direction, a plurality of piezoelectric elements 311 corresponding to each nozzle N are arranged for each of the first nozzle column L1 and the second nozzle column L2. Each piezoelectric element 311 is a passive element that is deformed by the supply of the aforementioned drive pulse PD. Each piezoelectric element 311 is formed into a long strip extending in the direction along the a-axis when viewed from above. The plurality of piezoelectric elements 311 are arranged in the direction along the b-axis in a manner corresponding to the plurality of pressure chambers Cv. When the vibration plate 316 vibrates in a manner linked to the deformation of the piezoelectric element 311, the pressure in the pressure chamber Cv changes, so that the ink is ejected from the nozzle N toward the c2 direction.

[0095] The housing 318 is a shell for storing ink supplied to the plurality of pressure chambers Cv. Figure 4 As shown, in the housing 318 of the present embodiment, a space Rb is formed for each of the first nozzle array L1 and the second nozzle array L2. The space Rb of the housing 318 and the space Ra of 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 liquid reservoir for storing ink supplied to a plurality of 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 chamber Cv through the supply liquid chamber 312c and each supply flow channel 312a. The vibration absorber 315 is a flexible, thin-film-like plastic substrate constituting the wall surface of the liquid storage chamber R, and absorbs the pressure fluctuation of the ink in the liquid storage chamber R.

[0096] The wiring substrate 317 is a plate-like component formed with wirings for electrically connecting the drive circuit 340 and the plurality of piezoelectric elements 311. The surface of the wiring substrate 317 facing the c2 direction is joined to the diaphragm 316 via a plurality of conductive bumps T. On the other hand, the drive circuit 340 is mounted on the surface of the wiring substrate 317 facing the c1 direction.

[0097] The drive circuit 340 is an IC (Integrated Circuit) chip that outputs a drive signal and a reference voltage for driving each of the piezoelectric elements 311. Specifically, the drive circuit 340 switches whether to supply the drive signal Com as a drive pulse PD for each of the plurality of piezoelectric elements 311 based on the aforementioned control signal SI.

[0098] On the surface of the wiring substrate 317 facing the c1 direction, although not shown, the end of an external wiring electrically connected to the control device 600 is joined. This external wiring is constituted by a connection component such as an FPC (Flexible Printed Circuits) or an FFC (Flexible Flat Cable), for example. Additionally, the wiring substrate 317 can also be an FPC or an FFC.

[0099] 1-4. Operations and Three-dimensional Object Printing Method of the Three-dimensional Object Printing Apparatus

[0100] Figure 5 is a flowchart showing the process of the three-dimensional object printing method according to the first embodiment. This three-dimensional object printing method is implemented using the three-dimensional object printing apparatus 100. In the three-dimensional object printing apparatus 100, as Figure 5 shown, first, in step S110, the workpiece W is set. Additionally, at this time, if necessary, instead of the workpiece W, or on the basis of the workpiece W, the object O is set. Furthermore, the setting of the workpiece or the object O can be implemented either by manual operation performed by the user or automatically by the operation of the robot 200 in accordance with the program PG1.

[0101] Next, in step S120, as described above, using the CAD data of the workpiece W, etc., the workpiece information Da is generated by the data generation unit 614. Thereafter, in step S130, the point data Dc is generated by the data generation unit 614. At this time, the detection operation MD corresponding to the number of cycles is performed N times. Then, in step S140, the printing operation MP corresponding to the number of cycles is performed N times using the point data Dc generated in step S130.

[0102] Figure 6 is showing Figure 5Flowchart of the process for generating the point data Dc shown below. Hereinafter, based on Figure 6 , the process of the processing in step S130 shown Figure 5 will be described. As shown Figure 6 below, first, a detection operation MD for detecting the actual scan path of the liquid ejection head 310 is performed.

[0103] In the detection operation MD, first, in step S131, based on the workpiece information Da, the data generation unit 614 generates point data Dc representing an ideal scan path as a reference path. Next, in step S132, using the point data Dc generated in step S131, while operating the robot 200, a detection pattern is printed on the workpiece W or the object O. Thereafter, in step S133, the actual scan path in step S132 is detected.

[0104] Next, in step S134, based on the detection result of the detection operation MD, that is, the actual scan path detected in step S133, the data generation unit 614 generates point data Dc representing the corrected path. Thereafter, a confirmation operation MC is performed.

[0105] In the confirmation operation MC, first, in step S135, using the point data Dc generated in step S134, while operating the robot 200, in the same manner as in the aforementioned step S132, a detection pattern is printed on the workpiece W or the object O. Next, in step S136, in the same manner as in the aforementioned step S133, the actual scan path in step S135 is detected. Thereafter, in step S137, it is determined whether the actual scan path detected in step S136 is the desired scan path. For example, when the difference between the actual scan path detected in step S136 and the reference path is within a predetermined range, it is determined that the actual scan path detected in step S136 is the desired scan path.

[0106] When the actual scan path is not the desired scan path, the process returns to the aforementioned step S134, and the point data Dc is adjusted so that the actual scan path approaches the reference path, and the data generation unit 614 regenerates the point data Dc representing the corrected path. On the other hand, when the actual scan path is the desired scan path, in step S138, it is determined whether it is the Nth cycle based on whether the number of transfers from step S137 is the Nth time.

[0107] In the case where the Nth cycle is not reached, return to the aforementioned step S131, and for subsequent cycles, perform the same processing as described above. On the other hand, in the case where the Nth cycle is reached, transfer to the aforementioned Figure 5 step S140 shown, and perform printing.

[0108] In addition, although it is possible to confirm that it is a desired path through the confirmation operation MC, the confirmation operation MC is not an essential operation in the present invention, and it can also be appropriately omitted according to the degree of the required printing quality, etc., so as to shorten the time required for the adjustment of the dot data. In other words, it is also possible to directly proceed to step S138 after the dot data Dc is generated in step S134.

[0109] Figure 7 is a diagram for explaining the detection operation MD and the printing operation MP in the first embodiment. In Figure 7 , an example is shown where the number of times of each of the detection operation MD and the printing operation MP, that is, the number of cycles, is two. In Figure 7 the example shown, in each operation, the liquid ejection head 310 performs scanning in the direction along the Y axis.

[0110] Although printing by the printing operation MP_1 of the first cycle is performed on the first region RP1 of the workpiece W, prior to this printing, the detection operation MD_1 of the first cycle is performed on the first region RP1 or the region corresponding thereto. Similarly, although printing by the printing operation MP_2 of the second cycle is performed on the second region RP2 of the workpiece W, prior to this printing, the detection operation MD_2 of the second cycle is performed on the second region RP2 or the region corresponding thereto. Here, the first region RP1 and the second region RP2 are offset and arranged in the direction along the X axis so that a part of each other overlaps. In the present embodiment, after the detection operations MD of the first cycle and the second cycle are sequentially performed, the printing operations MP of the first cycle and the second cycle are sequentially performed. In addition, the number of cycles can be one or three or more.

[0111] Figure 8 is a diagram for explaining the dot data Dc representing the ideal scanning path. In Figure 8 , the dot data Dc_1 representing the reference path RU_1 which is the ideal scanning path in the detection operation MD of the first cycle is shown. In addition, in Figure 8 , a plurality of nozzles N of the liquid ejection head 310 are schematically shown. Furthermore, although in Figure 8 the ideal scanning path is a straight line path along the scanning direction DS of the liquid ejection head 310, the ideal scanning path can also have curved or bent portions as needed.

[0112] In Figure 8 the example shown, the dot data Dc_1 is composed of 17 data items including the data PS, P1 to P15, and PE. The data PS represents the start position on the scanning path of the liquid ejection head 310. The data PE represents the end position on the scanning path of the liquid ejection head 310. The data P1 to P15 represent positions between the start position and the end position on the scanning path of the liquid ejection head 310. In addition, the number of data items representing positions between the start position and the end position on the scanning path of the liquid ejection head 310 is not limited to Figure 8 the example shown, but is arbitrary.

[0113] Figure 9 is a diagram for explaining the detection of the position related to the actual scanning path RUa in the case of using the dot data Dc_1 representing the ideal scanning path. In Figure 9 it, the first scanning path RUa_1 of the actual scanning path RUa in the detection operation MD of the first cycle is shown. In the detection operation MD of the first cycle, as Figure 9 shown, the first detection pattern PT1 is printed as a detection pattern.

[0114] In Figure 9 the example shown, the first detection pattern PT1 is composed of a plurality of markers M1. The plurality of markers M1 are formed by ejecting ink from each nozzle N at the positions shown by the aforementioned dot data Dc_1. In the case where the first scanning path RUa_1 is an ideal scanning path, the plurality of markers M1 of the first detection pattern PT1 are arranged in rows and columns in the X-axis direction and the Y-axis direction. In Figure 9 it, a state is shown in which the first scanning path RUa_1 is offset from the ideal scanning path in the X-axis direction and meanders, and accordingly, the arrangement of the plurality of markers M1 of the first detection pattern PT1 is skewed in the X-axis direction.

[0115] The detection of the first scanning path RUa_1 is performed using the captured information Db obtained by capturing the first detection pattern PT1 with the imaging device 330. This capture is performed, for example, while scanning the imaging device 330 together with the liquid ejection head 310 at the time of forming the first detection pattern PT1. In addition, this capture may also be performed by the imaging device 330 in another scan after the formation of the first detection pattern PT1.

[0116] In Figure 9In this case, the field of view angle AI of the imaging device 330 is shown by a dashed line. Preferably, the field of view angle AI includes two or more markers M1. When two or more markers M1 having different positions in the direction along the Y axis are included in the field of view angle AI, it is possible to detect the shift in the direction along the X axis or the shift in the direction along the Y axis of the actual position corresponding to between two adjacent data among the plurality of data represented by the point data Dc_1 based on the positional relationship of these markers M1. Further, when two or more markers M1 having different positions in the direction along the X axis are included in the field of view angle AI, it is also possible to detect the attitude around the Y axis based on the interval between these markers M1. Moreover, when two or more markers M1 having different positions in the direction along the Y axis and two or more markers M1 having different positions in the direction along the X axis are included in the field of view angle AI, it is also possible to detect the attitude around the Z axis of the liquid ejection head 310 based on the positional relationship of these markers M1.

[0117] Figure 10 This is a diagram for explaining the shift of the actual scan path RUa with respect to the ideal scan path. In Figure 10 this case, the first scan path RUa_1 of the actual scan path in the detection operation MD of the first cycle is shown in comparison with the reference path RU_1.

[0118] Figure 11 This is a diagram for explaining an example of the point data Dc_1 corrected based on the actual scan path RUa. In Figure 11 this case, the point data Dc_1 corrected using the detection result of the detection operation MD of the first cycle is shown. As Figure 11 shown, the point data Dc_1 generated in the above-described step S134 is obtained by obtaining a correction path RC_1 that moves in a manner to cancel the shift of the first scan path RUa_1 with respect to the reference path RU_1 and correcting the point data Dc_1 as representing the position of the correction path RC_1.

[0119] In Figure 11 the example shown, the absolute value of the difference between the reference path RU_1 and the correction path RC_1 is equal to the absolute value of the difference between the reference path RU_1 and the first scan path RUa_1. That is, when the absolute value of the difference between the reference path RU_1 and the correction path RC_1 is set as a correction amount obtained by multiplying the absolute value of the difference between the reference path RU_1 and the first scan path RUa_1 by a coefficient α, α is 1.

[0120] Figure 12 This is a diagram for explaining another example of the point data Dc_1 corrected based on the actual scan path RUa. InFigure 12 In the example shown, the absolute value of the difference between the reference path RU_1 and the correction path RC_1 is greater than the absolute value of the difference between the reference path RU_1 and the first scanning path RUa_1. That is, when the absolute value of the difference between the reference path RU_1 and the correction path RC_1 is set to 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 the coefficient α, α is greater than 1. In other words, the degree of correction of the point data Dc_1 based on the actual scanning path RUa can be arbitrarily set according to the coefficient α. Although in Figure 12 , the case where α is greater than 1 is shown, but α can also be set to be less than 1.

[0121] Figure 13 2 is a diagram for explaining the actual scanning path RUb when the corrected point data Dc_1 is used. Figure 13 , a state in which the first detection pattern PT1 is printed while the robot 200 is operated using the point data Dc_1 corrected based on the detection result of the first cycle detection operation MD in the confirmation operation MC. Figure 13 In the aforementioned Figure 12 The correction path RC_1 shown is shown for comparison with the actual scanning path, which corresponds to the second scanning path RUb_1 which is the actual scanning path in the first printing operation MP_1.

[0122] like Figure 13 As shown, in the second scanning path RUb_1, the deviation from the ideal scanning path is reduced. The detection of the actual scanning path in the confirmation operation MC is performed in the same manner as the detection of the first scanning path RUa_1.

[0123] Figure 14 , which is a diagram for explaining the detection of the actual scanning path RUa in the subsequent cycle. Figure 14 , a state in which the second detection pattern PT2 as the detection pattern in the detection operation MD of the second cycle is printed is shown.

[0124] exist Figure 14 In the example shown, the second detection pattern PT2 is composed of a plurality of marks M2. The plurality of marks M2 are formed by ejecting ink from each nozzle N for each position represented by the dot data Dc of the second cycle, similarly to the plurality of marks M1 of the first detection pattern PT1 described above. However, the second detection pattern PT2 is arranged at a position offset in the direction along the Y axis relative to the first detection pattern PT1. Therefore, the second detection pattern PT2 can be distinguished from the first detection pattern PT1 and detected based on the shooting result of the camera device 330.

[0125] Figure 15 This is a diagram for explaining the corrected scan path RUb in subsequent loops. In Figure 15 it shows a state where the corrected point data Dc using the detection result of the detection action MD based on the second loop is used in the confirmation action MC and the second detection pattern PT2 is printed while the robot 200 is operating. In addition, in Figure 15 it shows the corrected path RC_2, which is the path represented by the point data Dc, for comparison with the actual scan path. This actual scan path corresponds to the actual scan path in the second printing action MP_2, that is, the second scan path RUb_1.

[0126] As described above, the three-dimensional object printing apparatus 100 includes a liquid ejection head 310, a robot 200 as an example of a "moving mechanism", and a detection unit 615. As described above, the liquid ejection head 310 ejects ink as an example of a "liquid" onto the three-dimensional workpiece W. The robot 200 changes the relative position and attitude of the liquid ejection head 310 with respect to the workpiece W. The detection unit 615 detects the relative position of the liquid ejection head 310 with respect to the workpiece W or the object O. As described above, the three-dimensional object printing apparatus 100 of the present embodiment includes a camera device 330, and the detection unit 615 detects the relative position of the liquid ejection head 310 with respect to the workpiece W or the object O based on the imaging result of the camera device 330.

[0127] In particular, as described above, the three-dimensional object printing apparatus 100 performs a first detection action MD_1 and a first printing action MP_1. In the first detection action MD_1, while the robot 200 scans the liquid ejection head 310 along the first scan path RUa_1 with respect to the workpiece W or the object O, the detection unit 615 detects the position related to the first scan path RUa_1. In the first printing action MP_1, while the robot 200 scans the liquid ejection head 310 along the second scan path RUb_1 based on the detection result detected by the detection unit 615 in the first detection action MD_1, the liquid ejection head 310 ejects ink onto the first region RP1 of the workpiece W.

[0128] In the above-described three-dimensional object printing apparatus 100, since the second scanning path RUb_1 is based on the detection result detected by the detection unit 615 in the first detection operation MD_1, the first printing operation MP_1 can be performed using the second scanning path RUb_1 that corrects the deviation of the first scanning path RUa_1 with respect to the reference path RU_1. Here, when the deviation amount of the first scanning path RUa_1 with respect to the reference path RU_1 is the first amount, the path difference between the first scanning path RUa_1 and the second scanning path RUb_1 is the first path difference. When the deviation amount is the second amount greater than the first amount, the path difference is the second path difference greater than the first path difference. In other words, since the greater the path difference between the first scanning path RUa_1 and the reference path RU_1, the greater the correction amount, the path difference between the first scanning path RUa_1 and the second scanning path RUb_1 is also greater. Therefore, compared with the case where the first printing operation MP_1 is performed without performing the first detection operation MD_1, the print quality of the first region RP1 of the workpiece W can be improved.

[0129] In addition, since the printing performed by the first printing operation MP_1 is performed after the first detection operation MD_1, the printing speed can be increased compared with a configuration in which the scanning path is corrected by feedback control while detecting the above-described deviation. In contrast, in the configuration in which this feedback control is performed, since the printing speed is limited by this control cycle, it is difficult to increase the printing speed.

[0130] Further, although the deviation amount of the first scanning path RUa_1 with respect to the reference path RU_1 as the ideal scanning path is grasped based on the detection result detected by the detection unit 615 in the first detection operation MD_1, and the print data Img is corrected so as to cancel the deviation amount, or control is performed to transfer the nozzle corresponding to the ink ejection in the nozzle row direction so as to cancel the deviation amount, the print quality of the first region RP1 of the workpiece W can be improved without correcting the dot data Dc_1. However, in this case, since the effective printing width in the b-axis direction in one printing operation needs to be set narrower than the length of the nozzle row, the printing productivity is reduced.

[0131] In the first detection operation MD_1, the liquid ejection head 310 forms the first detection pattern PT1 by ejecting ink onto the workpiece W or the object O, and the detection unit 615 detects the position related to the first scanning path RUa_1 by detecting the first detection pattern PT1.

[0132] Here, the first detection pattern PT1 indicates the actual ejection position of the ink from the liquid ejection head 310 with respect to the workpiece W or the object O. Therefore, by using the first detection pattern PT1, the deviation of the first scan path RUa_1 with respect to the reference path RU_1 can be detected with higher accuracy compared to the case where the position related to the first scan path RUa_1 is detected without actually ejecting ink.

[0133] The three-dimensional object printing apparatus 100 of the present embodiment includes an imaging device 330. The detection unit 615 uses the imaging result of the imaging device 330 to detect the position related to the scan path of the liquid ejection head 310 with respect to the workpiece W or the object O.

[0134] Here, the first detection pattern PT1 of the present embodiment includes a plurality of markers M1 arranged at intervals from each other, and the imaging device 330 captures the first detection pattern PT1 with a field of view angle AI including two or more of the plurality of markers M1. Therefore, since two or more of the markers M1 are included in one captured image, it is easier to detect the positional relationship between the plurality of markers M1 with high accuracy compared to the case where only one marker M1 is included in one captured image, for example. Therefore, in such a detection, there is an advantage that it is easy to detect the deviation of the first scan path RUa_1 with respect to the reference path RU_1 with high accuracy. In particular, if the positional relationship between a plurality of markers M1 having different positions in the scan direction DS is detected, printing defects caused by the first printing operation MP_1, such as skewing in a direction crossing the scan direction DS in the printed image, are less likely to occur, and thus it is easy to improve the image quality of the printing in the first printing operation MP_1.

[0135] In addition, as described above, the position of the imaging device 330 relative to the liquid ejection head 310 is fixed. Therefore, the formation and shooting of the first detection pattern PT1 can be uniformly performed by one scan. As a result, compared with the case where the formation and shooting of the first detection pattern PT1 are performed by different scans, the time required for the first detection operation MD_1 can be shortened. Further, since the field of view angle AI of the imaging device 330 follows the movement of the liquid ejection head 310 accompanying the formation of the first detection pattern, even if the number of imaging devices 330 is one, the first detection pattern PT1 can be photographed by the imaging device 330 over the entire area in the scanning direction DS. Therefore, compared with the configuration in which the position of the imaging device 330 is fixed relative to the workpiece W or the object O, the structure of the three-dimensional object printing apparatus 100 can be simplified or the printable area can be expanded. In contrast, in the configuration in which the position of the imaging device 330 is fixed relative to the workpiece W or the object O, depending on the installation position or the number of the imaging devices 330, etc., the area where the first detection pattern PT1 can be formed or the printable area is limited according to the range that can be imaged by the imaging device 330.

[0136] Alternatively, the formation and shooting of the first detection pattern PT1 may be performed by different scans. In this case, the scanning speeds during the formation and shooting of the first detection pattern PT1 can be made different from each other. Therefore, there is an advantage that it is easy to improve the respective accuracies of the formation and shooting of the first detection pattern PT1.

[0137] In addition, as described above, the three-dimensional object printing apparatus 100 further performs a second detection operation MD_2 and a second printing operation MP_2. The second detection operation MD_2 is that, between the above-described first detection operation MD_1 and the first printing operation MP_1, while the robot 200 scans the liquid ejection head 310 relative to the workpiece W or the object O along the third scanning path RUa_2, the detection unit 615 detects the position related to the third scanning path RUa_2. The second printing operation MP_2 is that, while the robot 200 scans the liquid ejection head 310 relative to the workpiece W or the object O along the fourth scanning path RUb_2 based on the detection result detected by the detection unit 615, the liquid ejection head 310 ejects ink onto the second region RP2 that partially overlaps with the first region RP1 of the workpiece W.

[0138] Here, in the same manner as the relationship between the aforementioned first scanning path RUa_1 and the second scanning path RUb_1, when the offset of the third scanning path RUa_2 with respect to the reference path RU_2 is the third amount, the path difference between the third scanning path RUa_2 and the fourth scanning path RUb_2 is the third path difference. When the offset is the fourth amount greater than the third amount, the path difference is the fourth path difference greater than the third path difference. Therefore, in the same manner as the aforementioned printing for the first region RP1, compared with the case where the second printing operation MP_2 is performed without performing the second detection operation MD_2, the image quality of the printing for the second region RP2 of the workpiece W can be improved. Additionally, if the execution timing of the second printing operation MP_2 is after the second detection operation MD_2, it can be either before or after the first printing operation MP_1.

[0139] In addition, in the same manner as the first detection pattern PT1 in the aforementioned first detection operation MD_1, in the second detection operation MD_2, ink is ejected from the liquid ejection head 310 onto the workpiece W or the object O to form the second detection pattern PT2 at a position offset in the scanning direction DS of the liquid ejection head 310 with respect to the first detection pattern PT1. Then, the detection unit 615 detects the second detection pattern PT2 to detect the position related to the third scanning path RUa_2. Therefore, in the same manner as the case of using the first detection pattern PT1, by using the second detection pattern PT2, compared with the case of detecting the position related to the third scanning path RUa_2 without ejecting the actual ink, the offset of the third scanning path RUa_2 with respect to the reference path RU_2 can be detected with high precision.

[0140] Here, the second detection pattern PT2 is not only formed in a region different from the first detection pattern PT1 but also formed at a position offset in the scanning direction DS of the liquid ejection head 310 with respect to the first detection pattern PT1. Therefore, it is relatively easy to distinguish and detect the second detection pattern PT2 from the first detection pattern PT1. Additionally, it is also easy to detect the positional relationship between the first detection pattern PT1 and the second detection pattern PT2.

[0141] In the present embodiment, as described above, the shapes or colors of the first detection pattern PT1 and the second detection pattern PT2 are different from each other. Therefore, compared with the case where the shapes and colors of these patterns are the same, it is relatively easy to distinguish and detect the second detection pattern PT2 from the first detection pattern PT1.

[0142] In addition, the amount of ink used in forming the first detection pattern PT1 composed of a plurality of markers M1 as described above is less than the amount of ink used in the first printing operation MP_1. Therefore, compared with the case where the amount of ink used in forming the first detection pattern PT1 is more than the amount of ink used in the first printing operation MP_1, the influence of the first detection pattern PT1 in the first printing operation MP_1 on the print quality is reduced. Further, even for the second detection pattern PT2, similarly to the first detection pattern PT1, the influence of the second detection pattern PT2 in the second printing operation MP_2 on the print quality is reduced.

[0143] In addition, as described above, the three-dimensional object printing apparatus 100 further performs a confirmation operation MC between the first detection operation MD_1 and the first printing operation MP_1. In the confirmation operation MC, while the robot 200 scans the workpiece W or the object O along the scanning path based on the detection result detected by the detection unit 615 in the first detection operation MD_1 with the liquid ejection head 310, the detection unit 615 detects the position related to the scanning path. Therefore, based on the case where the second scanning path RUb_1 is confirmed to be the desired path based on the detection result of the detection unit 615 in the confirmation operation MC, the first printing operation MP_1 can be performed using the second scanning path RUb_1.

[0144] As described above, the robot 200 is an articulated robot that is connected to a control device 600, which is an example of a "robot controller", and is equipped with a liquid ejection head unit 300, which is an example of an end effector including a liquid ejection head 310. The robot 200 moves the liquid ejection head unit 300 along a linear path such as a straight line or a curved line by combining the movements of a plurality of joint portions 231 to 236. At this time, even if an ideal path, i.e., a reference path RU_1 or the like, is given to the robot 200 as an indication of the path along which the liquid ejection head 310 should move, due to various errors such as machining errors or assembly errors of each arm, mechanical vibrations of each arm, eccentricity of the motor or the speed reducer, and the resolution fineness of the rotary encoder, etc., movement errors of each joint portion occur at various timings, and thus the actual path meanders and deviates from the ideal path. Such a deviation is difficult to predict in advance. Therefore, when such an articulated robot is used as a moving mechanism, the effects produced by performing the first detection operation MD_1 and the first printing operation MP_1 become significant. In addition, even in a moving mechanism other than the articulated robot, that is, a mechanism that can move by combining the movements of a plurality of movable portions, the actual path similarly deviates from the ideal scanning path as described above. Therefore, it is equally useful to perform the first detection operation MD_1 and the first printing operation MP_1 on the basis of moving the liquid ejection head 310 along the ideal scanning path.

[0145] In addition, as described above, the three-dimensional object printing apparatus 100 further includes a data generation unit 614 that generates point data Dc representing the positions through which the liquid ejection head 310 should 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 the point data Dc_1 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.

[0146] Specifically, the data generation unit 614 corrects the point data Dc_1 used in the first detection operation MD_1 by making the second scanning path RUb_1 closer to the reference path RU_1 than the first scanning path RUa_1 based on the detection result of the detection unit 615 in the first detection operation MD_1, thereby generating the point data Dc_1 used in the first printing operation MP_1.

[0147] Here, based on the detection result of the detection unit 615 in the first detection operation MD_1, the data generation unit 614 corrects the dot data Dc_1 used in the first detection operation MD_1 in such a way that the position through which the liquid ejection head 310 should pass is shifted in a direction intersecting the first scan path P1a. Therefore, it is possible to make the second scan path RUb_1 closer to the reference path RU_1 than the first scan path RUa_1b.

[0148] As described above, in the first detection operation MD_1, either the workpiece W or the object O corresponding to the workpiece W was used. In the first detection operation MD_1, when the scanning of the liquid ejection head 310 by the robot 200 and the detection by the detection unit 615 were performed on the object O, the shape of the object O was substantially the same as the shape of the workpiece W. Between the first detection operation MD_1 and the first printing operation MP_1, the object O was replaced with the workpiece W. Therefore, the ink ejected in the first detection operation MD_1 does not affect the image quality of the printing on the workpiece W in the first printing operation MP_1.

[0149] On the other hand, in the first detection operation MD_1, when the scanning of the liquid ejection head 310 by the robot 200 and the detection by the detection unit 615 are performed on the workpiece W, there is an advantage that the labor and time for replacing the object O with the workpiece W as described above are not required.

[0150] 2. Second Embodiment

[0151] Figure 16 FIG. is a block diagram showing the electrical configuration of the three-dimensional object printing apparatus 100A according to the second embodiment. In the three-dimensional object printing apparatus 100A, 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 rest is the same as the three-dimensional object printing apparatus 100 of the first embodiment described above. In the liquid ejection head unit 300A, except that it has a distance sensor 360 instead of the imaging device 330, the rest is the same as the liquid ejection head unit 300. In the control device 600A, except that it uses a program PG2 instead of the program PG1, the rest is the same as the control device 600.

[0152] In the control device 600A, the processing circuit 610 functions as an information acquisition unit 611, an arm control unit 612, an ejection control unit 613, a data generation unit 614, and a detection unit 615A by executing the program PG2 stored in the storage circuit 620.

[0153] The detection unit 615A uses the measurement information Dd that is the measurement result of the distance sensor 360 to detect the position related to the scanning path of the liquid ejection head 310 relative to the workpiece W or the object O.

[0154] Figure 17 FIG. For explaining the detection of the actual scanning path RUa in the second embodiment. As Figure 17 shown, the distance sensor 360 is a displacement sensor that measures the distance from the reference plane RF fixed relative to the workpiece W to the relative position. The reference plane RF in this embodiment is exemplified as a plane facing the X2 direction. Here, the detection axis AS of the distance sensor 360 intersects the reference plane RF. In Figure 17 the example shown, the detection axis AS faces the X1 direction. In addition, the reference plane RF only needs to be fixed relative to the workpiece W in terms of relative position, and can be the surface of any object, the surface of the workpiece W, or the surface of an object such as a plate separated from the workpiece W. Furthermore, the direction in which the reference plane RF faces only needs to be able to grasp the position and attitude relative to the surface WF of the workpiece W in advance, and is not limited to the X2 direction and is arbitrary.

[0155] The process of the three-dimensional printing method using the three-dimensional printing apparatus 100A will be described. Although this three-dimensional printing method is based on the basic sequence and is Figure 5 and Figure 6 the flowchart description is the standard, in this embodiment, different from the first embodiment, the printing of the detection pattern in step S132 and step S135 is not performed.

[0156] In this three-dimensional printing method, first, the workpiece W is set in the same manner as in the first embodiment. In addition, at this time, if necessary, instead of the workpiece W or on the basis of the workpiece W, the object O is set. In addition, the setting of the workpiece or the object O can be implemented by manual work performed by the user or automatically by the operation of the robot 200 in accordance with the program PG2.

[0157] Next, using the CAD data of the workpiece W, etc., the workpiece information Da is generated by the data generation unit 614. After that, the point data Dc is generated by the data generation unit 614. In the generation process of this point data Dc, based on the workpiece information Da, the data generation unit 614 generates the point data Dc that represents the ideal scanning path as the reference path.

[0158] Next, the detection operation MD is executed. In the detection operation MD, while the robot 200 is operated using the point data Dc representing the ideal scanning path, as Figure 17The measurement information Dd, which is the measurement result of the distance sensor 360, is used as shown to detect the position related to the scanning path of the liquid ejection head 310 relative to the workpiece W or the object O.

[0159] Next, based on the detection result of the detection operation MD, that is, the actual scanning path RUa, the point data Dc representing the corrected path is generated by the data generation unit 614. Then, using the point data Dc representing the corrected path, the printing operation MP is performed on the workpiece W, thereby forming the image based on the printing data Img on the surface of the workpiece W.

[0160] Even in the three-dimensional printing method using the three-dimensional printing apparatus 100A, the N detection operations MD corresponding to the number of cycles and the N printing operations MP can be performed in the same manner as in the first embodiment. In addition, the confirmation operation MC can be performed between the detection operation MD and the printing operation MP in the same manner as in the first embodiment.

[0161] As described above, the three-dimensional printing apparatus 100A of the present embodiment further includes a distance sensor 360. The detection unit 615A uses the measurement result of the distance sensor 360 to detect the position related to the scanning path of the liquid ejection head 310 relative to the object O. Here, the relative position of the distance sensor 360 with respect to the liquid ejection head 310 is fixed. Moreover, in the first detection operation MD_1, the distance sensor 360 measures the distance to the reference plane RF whose relative position with respect to the workpiece W is fixed. Therefore, even if the ink is not actually ejected from the liquid ejection head 310, the position related to the scanning path of the liquid ejection head 310 can be detected based on the measurement result of the distance sensor 360. As a result, compared with the configuration in which the detection pattern is printed as described in the first embodiment, the amount of ink used can be reduced. In addition, in the case where the object O is not used, compared with the configuration in which the detection pattern is printed as described in the first embodiment, it is possible to prevent the detection pattern from affecting the image formed on the workpiece W.

[0162] In the present embodiment, in the first detection operation MD_1, the detection axis AS of the distance sensor 360 intersects the scanning direction DS of the liquid ejection head 310. Therefore, the position related to the scanning path of the liquid ejection head 310 can be detected based on the measurement result of the distance sensor 360. In particular, when the detection axis AS of the distance sensor 360 is not only the scanning direction DS of the liquid ejection head 310 but also intersects the ejection direction of the ink from the liquid ejection head 310, for example, there is an advantage that it is easy to detect the deviation of the scanning path meandering with respect to the reference path RU_1 with high accuracy when the detection axis AS is along the X axis as in the present embodiment.

[0163] 3. Variation Examples

[0164] Each of the above examples can be varied in various ways. Hereinafter, specific variation methods applicable to each of the above methods will be exemplified. In addition, two or more methods arbitrarily selected from the following examples can be appropriately combined within a non - conflicting range.

[0165] 3 - 1. Variation Example 1

[0166] Although in the above method, a structure using a six - axis vertical multi - axis robot is exemplified as the moving mechanism, it is not limited to this structure. The moving mechanism only needs to be able to three - dimensionally change the relative position and attitude of the liquid ejection head with respect to the workpiece. Therefore, the moving mechanism can be, for example, a vertical multi - axis robot other than six - axis or a horizontal multi - axis robot. In addition, the movable part of the robotic arm is not limited to the rotational mechanism. For example, it can also be a telescopic mechanism or the like. Or, as long as it can three - dimensionally change the position of the liquid ejection head, it can also be something other than a robotic arm.

[0167] 3 - 2. Variation Example 2

[0168] In the above method, a structure using screw fixation or the like is exemplified as the method of fixing the liquid ejection head to the tip of the robotic arm, but it is not limited to this structure. For example, the liquid ejection head can also be clamped by a clamping mechanism such as a gripper installed at the tip of the robotic arm, thereby fixing the liquid ejection head to the tip of the robotic arm.

[0169] 3 - 3. Variation Example 3

[0170] In addition, although in the above method, a moving mechanism for moving the liquid ejection head is exemplified, it is not limited to this structure. For example, it can also be a structure in which the position of the liquid ejection head is fixed and the moving mechanism moves the workpiece, thereby three - dimensionally changing the relative position and attitude of the workpiece with respect to the liquid ejection head. In this case, for example, the workpiece is clamped by a clamping mechanism such as a gripper installed at the tip of the robotic arm.

[0171] 3 - 4. Variation Example 4

[0172] Although in the above method, a structure for printing using one type of ink is exemplified, it is not limited to this structure, and the present invention can also be applied to a structure for printing using two or more types of ink.

[0173] 3 - 5. Variation Example 5

[0174] The use of the three-dimensional object printing apparatus of the present invention is not limited to printing. For example, a three-dimensional object printing apparatus that ejects a solution of a color material can be used as a manufacturing apparatus for forming a color filter of a liquid crystal display device. In addition, a three-dimensional object printing apparatus that ejects a solution of a conductive material can be used as a manufacturing apparatus for forming wirings or electrodes of a wiring substrate. Further, the three-dimensional object printing apparatus can also be used as a jet dispenser that applies a liquid such as an adhesive to a workpiece.

[0175] Symbol Description

[0176] 100... Three-dimensional object printing apparatus; 100A... Three-dimensional object printing apparatus; 200... Robot (moving 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... Field of view angle; 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 plane; RP1... First region; RP2... Second region; 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... Workpiece.

Claims

1. A three-dimensional object printing device, characterized in that, have: A liquid ejection head ejects liquid toward a three-dimensional workpiece; a moving mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece; a detection unit for detecting a relative position of the liquid ejection head relative to the workpiece or the object; a data generating unit for generating point data indicating a position where the liquid ejection head should pass; The three-dimensional object printing device performs a first detection action and a first printing action, wherein: The first detection action is an action in which the detection unit detects a position related to the first scanning path while the moving mechanism scans the liquid ejection head relative to the workpiece or the object along the first scanning path. The first printing action is an action in which the liquid ejection head ejects liquid toward a first area of the workpiece while the moving mechanism scans the liquid ejection head relative to the workpiece along a second scanning path based on a detection result detected by the detection unit in the first detection action. The moving mechanism is a multi-joint robot equipped with an end effector including the liquid ejection head. The multi-joint robot is connected to a robot controller. The robot controller controls the driving of the multi-joint robot based on the point data from the data generating unit. The data generating unit generates dot data used in the first printing operation by correcting dot data used in the first detection operation so that the second scanning path is closer to a reference path than the first scanning path based on a detection result of the detecting unit in the first detection operation.

2. The three-dimensional object printing device according to claim 1, characterized in that: In the first detection operation, the liquid ejection head forms a first detection pattern by ejecting liquid toward the workpiece or the object, and the detection unit detects the position related to the first scanning path by detecting the first detection pattern.

3. The three-dimensional object printing device according to claim 2, characterized in that: It also has a camera device. The detection unit detects the position of the liquid ejection head relative to the workpiece or the object in relation to the scanning path using the image pickup result of the image pickup device. The first detection pattern includes a plurality of marks arranged at intervals from each other, The imaging device captures the first detection pattern at a field angle including two or more of the plurality of marks.

4. The three-dimensional object printing device according to claim 3, characterized in that: The position of the imaging device relative to the liquid ejection head is fixed.

5. The three-dimensional object printing device according to claim 2, wherein: A second detection action and a second printing action are further performed, wherein: The second detection action is an action in which, between the first detection action and the first printing action, while the moving mechanism scans the liquid ejection head relative to the workpiece or the object along a third scanning path, the detection unit detects a position related to the third scanning path. The second printing action is an action in which, while the moving mechanism scans the liquid ejection head relative to the workpiece along a fourth scanning path based on the detection result detected by the detection unit, the liquid ejection head ejects liquid onto a second region that partially overlaps with the first region of the workpiece.

6. The three-dimensional object printing apparatus according to claim 5, wherein: In the second detection action, the liquid ejection head forms a second detection pattern at a position offset in the scanning direction of the liquid ejection head relative to the first detection pattern by ejecting liquid onto the workpiece or the object, and the detection unit detects a position related to the third scanning path by detecting the second detection pattern.

7. The three-dimensional object printing apparatus according to claim 6, wherein: The shapes or colors of the first detection pattern and the second detection pattern are different from each other.

8. The three-dimensional object printing apparatus according to claim 2, wherein: The amount of liquid used in forming the first detection pattern is less than the amount of liquid used in the first printing action.

9. The three-dimensional object printing apparatus according to claim 1, wherein: Between the first detection action and the first printing action, a confirmation action is further performed. The confirmation action is an action in which, while the moving mechanism scans the liquid ejection head relative to the workpiece or the object along a scanning path based on the detection result detected by the detection unit in the first detection action, the detection unit detects a position related to this scanning path.

10. The three-dimensional object printing apparatus according to claim 1, wherein: It further includes a distance sensor. The detection unit uses the measurement result of the distance sensor to detect a position related to the scanning path of the liquid ejection head relative to the workpiece. The relative position of the distance sensor with respect to the liquid ejection head is fixed. In the first detection action, the distance sensor measures the distance to a reference plane whose relative position with respect to the workpiece is fixed.

11. The three-dimensional object printing apparatus according to claim 10, wherein: In the first detection action, the detection axis of the distance sensor intersects the scanning direction of the liquid ejection head.

12. The three-dimensional object printing apparatus according to claim 1, wherein: The data generation unit corrects the dot data used in the first detection action based on the detection result of the detection unit in the first detection action, so as to offset the position where the liquid ejection head should pass in a direction intersecting the first scanning path.

13. A method for printing a three-dimensional object, characterized in that, It is a three-dimensional object printing method for printing a workpiece by using a liquid ejection head that ejects liquid onto the three-dimensional workpiece, a moving mechanism that changes the relative position of the liquid ejection head with respect to the workpiece or an object corresponding to the workpiece, a robot controller, and a data generation unit. The moving mechanism is a multi-joint robot equipped with an end effector including the liquid ejection head. The robot controller is connected to the multi-joint robot. The data generation unit generates point data indicating the positions that the liquid ejection head should pass through. In the three-dimensional object printing method, a first detection operation, a first printing operation, and the following processes are performed, where The first detection operation is an operation of detecting positions related to the first scan path while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece or the object along the first scan path. The first printing operation is an operation in which the liquid ejection head ejects liquid onto a first area of the workpiece while the moving mechanism relatively scans the liquid ejection head with respect to the workpiece along a second scan path based on the detection result in the first detection operation. The process is a process of correcting the point data used in the first detection operation based on the detection result of the detection unit in the first detection operation so that the second scan path is closer to a reference path than the first scan path, thereby generating the point data used in the first printing operation.

14. The three-dimensional object printing method according to claim 13, characterized in that In the first detection operation, the liquid ejection head is scanned by the moving mechanism with respect to the object. The shape of the object is substantially the same as the shape of the workpiece. The object is replaced with the workpiece between the first detection operation and the first printing operation.

15. The three-dimensional object printing method according to claim 13 or 14, characterized in that In the first detection operation, the liquid ejection head is scanned by the moving mechanism with respect to the workpiece.

Images