Stereolithography apparatus

Abstract

A three-dimensional object printing device that can print a wide range of shapes of a three-dimensional workpiece. The three-dimensional object printing device includes a first robot arm that supports a head having a nozzle that ejects a liquid and changes the position and attitude of the head, and a second robot arm that supports a three-dimensional workpiece and changes the position and attitude of the workpiece.

Description

Technical Field

[0001] This invention relates to a three-dimensional printing apparatus. Background Technology

[0002] A three-dimensional printing apparatus is known for printing on the surface of a three-dimensional workpiece using an inkjet method. For example, Patent Document 1 describes a printing apparatus that performs printing while changing the relative position of the workpiece and the print head using a multi-joint robotic arm.

[0003] In the printing apparatus described in Patent Document 1, since the position and posture of the printed object are fixed, there are areas where the print head cannot be brought close to the printed object simply by the movement of a multi-joint robotic arm, depending on the shape of the printed object. Therefore, the printing apparatus described in Patent Document 1 has the problem of not being able to properly print on three-dimensional printed objects of various shapes.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2017-19183 Summary of the Invention

[0005] To address the above-mentioned issues, one aspect of the three-dimensional printing apparatus of the present invention comprises: a first robotic arm that supports a head having a nozzle for ejecting liquid and changes the position and orientation of the head; and a second robotic arm that supports a three-dimensional workpiece and changes the position and orientation of the workpiece. Attached Figure Description

[0006] Figure 1 A perspective view showing the outline of the three-dimensional printing apparatus according to the first embodiment.

[0007] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus according to the first embodiment.

[0008] Figure 3 This is a 3D view of the first robotic arm.

[0009] Figure 4 A three-dimensional view showing the general structure of the liquid ejection unit.

[0010] Figure 5 This is a top view of the three-dimensional printing apparatus according to the first embodiment.

[0011] Figure 6 This is a flowchart illustrating the operation of the three-dimensional printing apparatus according to the first embodiment.

[0012] Figure 7 This is a diagram used to illustrate the material supply process.

[0013] Figure 8 This diagram illustrates the movement of the first robotic arm during the first printing step.

[0014] Figure 9 This diagram illustrates the printing area of ​​the workpiece in the first printing step.

[0015] Figure 10 This is a diagram used to illustrate the avoidance procedure.

[0016] Figure 11 This is a diagram used to illustrate the movement steps.

[0017] Figure 12 This is a diagram used to illustrate the hardening and maintenance steps.

[0018] Figure 13 This is a diagram used to illustrate the material removal process.

[0019] Figure 14 This is a flowchart illustrating the operation of the three-dimensional printing apparatus according to the second embodiment.

[0020] Figure 15 A flowchart illustrating the operation of the three-dimensional printing apparatus involved in Modification Example 1.

[0021] Figure 16 This is a top view of the three-dimensional printing apparatus involved in Variation Example 1. Detailed Implementation

[0022] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions or scales of the various parts in the drawings differ appropriately from the actual figures, and some parts are shown schematically for ease of understanding. Furthermore, unless otherwise specifically limited in the following description, the scope of the present invention is not limited to these embodiments.

[0023] The following explanation uses intersecting X, Y, and Z axes appropriately. Furthermore, a direction along the X-axis will be referred to as the X1 direction, and the opposite direction will be referred to as the X2 direction. Similarly, opposite directions along the Y-axis will be referred to as the Y1 and Y2 directions. Furthermore, opposite directions along the Z-axis will be referred to as the Z1 and Z2 directions.

[0024] Here, the X, Y, and Z axes are coordinate axes set within a universal coordinate system that houses the first robotic arm 3 and the second robotic arm 4, described below. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction within the vertical direction. A base coordinate system, referenced to the base of each of the first robotic arm 3 and the second robotic arm 4, is established to correspond with this universal coordinate system through calibration. In the following examples, for convenience, the use of the universal coordinate system as the robotic arm coordinate system to control the movements of each of the first robotic arm 3 and the second robotic arm 4 will be illustrated.

[0025] Additionally, the Z-axis does not have to be a vertical axis. Furthermore, although the X, Y, and Z axes are typically orthogonal, this is not a limitation, and there are cases where they are not orthogonal. For example, the X, Y, and Z axes only need to intersect each other at an angle between 80° and 100°.

[0026] 1. First Implementation Method

[0027] 1-1. Overview of a 3D printing apparatus

[0028] Figure 1 This is a perspective view showing the outline of the three-dimensional printing apparatus 1 according to the first embodiment. The three-dimensional printing apparatus 1 is an apparatus that uses a first robotic arm 3 and a second robotic arm 4 to perform printing on the surface of a three-dimensional workpiece W by inkjet printing.

[0029] exist Figure 1 In the example shown, the workpiece W is an ellipsoidal rugby ball. Furthermore, the shape or size of the workpiece W is not limited to... Figure 1 The example shown is not for any particular form.

[0030] like Figure 1 As shown, the stereoscopic printing apparatus 1 includes a base 2, a first robotic arm 3, a second robotic arm 4, a liquid ejection unit 5, an ink supply unit 6, an imaging unit 7, a maintenance unit 8, a mounting section 9, a hardening unit 10, a controller 11, a control module 12, and a computer 13. The following will first discuss... Figure 1 Each part of the three-dimensional printing apparatus 1 shown will be briefly described in turn.

[0031] The base 2 is a platform having a surface 2a that supports the first robotic arm 3 and the second robotic arm 4. Surface 2a faces the Z1 direction. In this embodiment, surface 2a supports not only the first robotic arm 3 and the second robotic arm 4, but also the ink supply unit 6, the imaging unit 7, the maintenance unit 8, the mounting part 9, and the hardening unit 10. Here, each of the first robotic arm 3, the second robotic arm 4, the ink supply unit 6, the imaging unit 7, the maintenance unit 8, the mounting part 9, and the hardening unit 10 is fixed to the base 2 directly or indirectly via other components, such as by screws.

[0032] exist Figure 1 In the example shown, the base 2 is box-shaped, and the controller 11 and control module 12 are housed inside the base 2. Furthermore, an exhaust port 2b is provided on surface 2a of the base 2. An exhaust mechanism (not shown) is connected to the exhaust port 2b. This exhaust mechanism draws in gas from surface 2a of the exhaust port 2b, performs purification and other treatments on the drawn gas, and then discharges the gas to the outside.

[0033] Although detailed illustrations are omitted, as... Figure 1 As shown by the double-dotted line, a housing 20 is positioned in the Z1 direction relative to the base 2. The housing 20 is a structure that forms a space between itself and the surface 2a to accommodate structures such as the first robotic arm 3 and the second robotic arm 4 supported on the base 2. The housing 20 has, for example, multiple columns and beams made of metal or the like, and multiple panels such as a top plate and wall panels made of a transparent material such as acrylic resin. Furthermore, a window is provided on the housing 20 for supplying and removing the workpiece W to and from the mounting section 9.

[0034] Furthermore, the structure of base 2 is not limited to Figure 1 The example shown is not a representation of any structure. Furthermore, the base 2 can be omitted as needed. In this case, the structural elements of the stereolithography printing apparatus 1 may be provided on, for example, the floor, wall, or ceiling of a building. In other words, the base 2 may not be a structural element of the stereolithography printing apparatus 1, but may be, for example, the floor, wall, or ceiling of a building. Although in this embodiment, the structural elements of the stereolithography printing apparatus 1 other than the base 2 are supported on a surface 2a that is a single plane, these structural elements may also be supported on surfaces facing different directions. For example, the first robotic arm 3 may be provided on one of the floor, wall, and ceiling, and the second robotic arm 4 may be provided on another of them. Furthermore, the first robotic arm 3 may be provided on one of several walls facing different directions, and the second robotic arm 4 may be provided on another of them.

[0035] The first robotic arm 3 is a robotic arm that changes the position and orientation of the liquid ejection unit 5 in the general coordinate system. Figure 1 In the example shown, the first robotic arm 3 is a so-called six-axis vertical multi-joint robotic arm, and at the tip of the arm of the first robotic arm 3, a liquid ejection unit 5 is installed as an end effector in a fixed state by means of screws or the like. Furthermore, the structure of the first robotic arm 3 will be based on... Figure 3 This will be described later.

[0036] The liquid ejection unit 5 is a device having a head 5a that ejects ink, an example of "liquid," toward the workpiece W. In this embodiment, the liquid ejection unit 5, in addition to the head 5a, also includes a pressure regulating valve 5b and a pre-curing light source 5c. Furthermore, the structure of the liquid ejection unit 5 will be based on... Figure 4 This will be described later.

[0037] The ink is not particularly limited, and examples include aqueous inks that dissolve color materials such as dyes or pigments in aqueous solvents, UV-curable inks that use curable resins, and solvent-based inks that dissolve color materials such as dyes or pigments in organic solvents. Curable inks are preferred. While the curable ink is not particularly limited, it can be any of the following types: thermosetting, photocurable, radiation-curable, and electron beam-curable, but photocurable types such as UV-curable are preferred. Furthermore, the ink is not limited to a solution and can also be an ink in which color materials are dispersed as a dispersion phase in a dispersant. Moreover, the ink is not limited to inks containing color materials; for example, it can be an ink that contains conductive particles such as metal particles used to form wiring as a dispersion phase, a transparent ink, or a treatment liquid used for surface treatment of workpiece W.

[0038] On the other hand, the second robotic arm 4 is a robotic arm that changes the position and orientation of the workpiece W in the general coordinate system. Figure 1 In the example shown, the second robotic arm 4 is a six-axis vertical multi-joint robotic arm, and at the top of the arm of the second robotic arm 4, a gripper mechanism 40 is installed as an end effector in a fixed state by means of screw fastening.

[0039] Furthermore, the second robotic arm 4 is constructed in the same manner as the first robotic arm 3, except for the end effector it is fitted with. However, the first robotic arm 3 and the second robotic arm 4 can also have different structures. In this embodiment, the arm length or the weight that can be lifted may differ depending on the requirements. In addition, the number of joints in the first robotic arm 3 and the second robotic arm 4 may also differ.

[0040] The gripper mechanism 40 is a robotic arm gripper that holds the workpiece W in a loading and unloading manner. Here, "holding" encompasses both adsorption and gripping. Figure 1 In the example shown, the gripper mechanism 40 is a mechanism that uses negative pressure to attract the workpiece W. Furthermore, the structure of the gripper mechanism 40 is appropriately determined according to the shape, size, or material of the workpiece W. The gripper mechanism 40 is not limited to an attraction mechanism achieved by negative pressure; for example, it can also be an attraction mechanism achieved by magnetic force, or a gripping gripper mechanism with multiple fingers or claws.

[0041] The ink supply unit 6 is a mechanism for supplying ink to the liquid ejection unit 5. Figure 1 In the example shown, the ink supply unit 6 includes an ink tank 6a, a supply pipe 6b, a secondary tank 6c, and a supply pipe 6d. The ink tank 6a is a container for storing ink and is made of, for example, a flexible film. The supply pipe 6b is a pipe connecting the ink tank 6a and the secondary tank 6c and is made of, for example, a rubber or elastomer material. The secondary tank 6c is a container for storing ink supplied from the ink tank 6a via the supply pipe 6b and is made of, for example, a resin or metal material. Ink can be supplied from the ink tank 6a to the secondary tank 6c, for example, by means of a pump (not shown) located midway through the supply pipe 6b. The supply pipe 6d is a pipe connecting the secondary tank 6c and the liquid ejection unit 5 and is made of, for example, a rubber or elastomer material. By making the supply pipe 6d flexible, changes in the position and orientation of the liquid ejection unit 5 are permitted.

[0042] Here, the auxiliary tank 6c is fixed to the housing 20 at a position higher in the vertical direction than the moving area of ​​the liquid ejection unit 5. Therefore, since the auxiliary tank 6c is always positioned in the Z1 direction relative to the liquid ejection unit 5, ink can be supplied from the auxiliary tank 6c to the liquid ejection unit 5 at a predetermined pressure even without using a pump or similar mechanism. Alternatively, the auxiliary tank 6c can be omitted. In this case, for example, only a pump needs to be used to supply ink from the ink tank 6a to the liquid ejection unit 5 at a predetermined pressure.

[0043] The imaging unit 7 is a device for detecting the position and orientation of the workpiece W. The imaging unit 7 includes an imaging device 7a and an illumination unit 7b. The imaging device 7a, generally referred to as a vision sensor, is a camera including an imaging optical system and an imaging element, and it captures images of objects located within the imaging range. The imaging optical system is an optical system including at least one imaging lens, and may also include various optical elements such as prisms, zoom lenses, or focusing lenses. The imaging element is, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor. In the imaging device 7a, a two-axis or three-axis imaging coordinate system is set with any point in the captured image as a reference. This imaging coordinate system is calibrated to establish a correspondence with the aforementioned base coordinate system or general coordinate system. The illumination unit 7b is a light source including a light-emitting element such as an LED (light emitting diode), and it emits light towards the imaging range of the imaging device 7a. When a workpiece W is photographed as an object through illumination by the illumination unit 7b, the contrast of the image captured by the imaging device 7a can be improved. As a result, the accuracy of detecting the position and orientation of the workpiece W obtained based on the imaging results from the imaging device 7a can be improved. Furthermore, the illumination unit 7b is appropriately provided with optical components such as lenses or reflectors for adjusting the light emission direction or emission range. Additionally, the light emission direction of the illumination unit 7b is the Y1 direction, and the light emitted from the illumination unit 7b diffuses in the X and Z directions as it moves towards the Y1 direction from the illumination unit 7b.

[0044] Maintenance unit 8 is a mechanism for performing maintenance on the head 5a of liquid ejection unit 5. Figure 1In the example shown, maintenance unit 8 is divided into unit 8a and unit 8b. Although not shown, unit 8a includes a cover, a wiper, and a suction mechanism. The cover is formed of an elastic component such as rubber and prevents the ink near the nozzle of head 5a from drying by covering the nozzle and nozzle surface of head 5a, which will be described later. Furthermore, when the ink is photocurable, the cover blocks external light by covering the nozzle surface of head 5a, thereby preventing the ink near the nozzle of head 5a from becoming viscous or curing. The wiper cleans the nozzle surface of head 5a by wiping it. The suction mechanism refreshes the ink within the nozzle by drawing ink from the nozzle of head 5a while the nozzle surface is covered by the cover. Unit 8b is a mechanism for checking the ink ejection function of head 5a. For example, unit 8b supports a medium such as paper or film used for printing inspection patterns. Furthermore, the structure of maintenance unit 8 is not limited to the structure described above; for example, unit 8b may be omitted.

[0045] The mounting section 9 is a platform with a surface 9a for mounting the workpiece W in order to perform material feeding and removal. The mounting section 9 is positioned so that the workpiece W can be fed and removed from the outside of the housing 20. Figure 1 In the example shown, surface 9a can hold two workpieces W. Thus, by enabling surface 9a to hold multiple workpieces W, it is possible to pre-position workpieces W for subsequent printing on surface 9a while leaving an area for removing workpieces W currently being printed. Although not shown, surface 9a is appropriately formed with recesses or protrusions to stabilize the position and orientation of the placed workpieces W. Furthermore, the structure of the mounting portion 9 is not limited to... Figure 1 The example shown is not for any specific structure.

[0046] The hardening unit 10 is a mechanism for hardening or curing the ink on the workpiece W. Figure 1In the example shown, the hardening unit 10 includes a light-shielding member 10a and a light source 10b. The light-shielding member 10a is a box-shaped light-shielding member with an opening in the Z1 direction, formed to allow the workpiece W to enter, and is made of, for example, resin or metal. The light source 10b is disposed inside the light-shielding member 10a. The light source 10b emits energy such as light, heat, electron beams, or radiation to harden or cure the ink. For example, in the case of an ultraviolet-curing ink, the energy is ultraviolet light, and the light source 10b is composed of a light-emitting element such as an LED (light emitting diode) that emits ultraviolet light. In addition, the light source 10b may also have optical components such as lenses for adjusting the emission direction or emission range of the energy. Furthermore, in addition to the light source 10b, a mirror or the like may be provided inside the light-shielding member 10a to reflect the light from the light source 10b.

[0047] Controller 11 is a robotic arm controller that controls the drive of the first robotic arm 3 and the second robotic arm 4. Control module 12 is a circuit module that is communicatively connected to controller 11 and controls the liquid ejection unit 5. Computer 13 is communicatively connected to controller 11 and control module 12. Although in Figure 1 In the example shown, computer 13 is a laptop, but it is not limited to this; for example, computer 13 could also be a desktop computer. The following is based on... Figure 2 The electrical structure of the three-dimensional printing apparatus 1 will now be explained.

[0048] 1-2. Electrical Structure of the Three-Dimensional Printing Apparatus

[0049] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 1 according to the first embodiment. Figure 2 The electrical structural elements of the three-dimensional printing apparatus 1 are shown in the diagram. Additionally, Figure 1 The electrical structural elements shown can be appropriately divided, partially included in other structural elements, or integrated with other structural elements. For example, some or all of the functions of the controller 11 or control module 12 can be implemented by the computer 13, or by other external devices such as a PC (personal computer) connected to the controller 11 via a network such as a LAN (Local Area Network) or the Internet.

[0050] The controller 11 has the function of controlling the drive of the first robotic arm 3 and the second robotic arm 4, and the function of generating a signal D3 to synchronize the ink ejection action in the liquid ejection unit 5 with the action of the first robotic arm 3. The controller 11 has a storage circuit 11a and a processing circuit 11b.

[0051] The storage circuit 11a stores various programs executed by the processing circuit 11b and various data processed by the processing circuit 11b. The storage circuit 11a may include, for example, a semiconductor memory comprising one or both of the following: volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable Read-Only Memory). Alternatively, part or all of the storage circuit 11a may be included in the processing circuit 11b.

[0052] The storage circuit 11a stores path information Da and path information Db. Path information Da represents the path that the liquid ejection unit 5 should move along and the orientation of the liquid ejection unit 5 along that path. Path information Db represents the path that the gripper mechanism 40 should move along and the orientation of the gripper mechanism 40 along that path. Each of these pieces of information is represented, for example, using coordinate values ​​from a base coordinate system or a universal coordinate system. Furthermore, each of these pieces of information is determined based on the shape of the workpiece W, etc. The shape of the workpiece W is obtained, for example, by using CAD (computer-aided design) data representing the three-dimensional shape of the workpiece W.

[0053] Here, the path information Db contains information related to the position and orientation of the workpiece W during printing. Furthermore, the path information Da contains information related to the position and orientation of the liquid ejection unit 5 during printing. The position and orientation of the liquid ejection unit 5 during printing are determined based on information such as the CAD data of the workpiece W, and the position and orientation of the workpiece W during printing. Each of the above path information Da and path information Db is input from the computer 13 to the storage circuit 11a.

[0054] Processing circuit 11b controls the movement of arm drive mechanism 3a of the first robotic arm 3 based on path information Da, and generates signal D3. Furthermore, processing circuit 11b controls the movement of arm drive mechanism 4a of the second robotic arm 4 based on path information Db. Here, processing circuit 11b corrects the movement of at least one of the arm drive mechanism 3a and arm drive mechanism 4a during printing based on the imaging results of imaging unit 7. In this embodiment, processing circuit 11b corrects the movement of arm drive mechanism 4a during printing based on the imaging results of imaging unit 7. Processing circuit 11b includes, for example, one or more processors such as CPU (Central Processing Unit). Alternatively, processing circuit 11b may replace a CPU or include programmable logic devices such as FPGA (Field-Programmable Gate Array) in addition to a CPU.

[0055] The arm drive mechanism 3a includes a motor for driving each joint of the first robotic arm 3 and an encoder for detecting the rotation angle of each joint of the first robotic arm 3. Similarly, the arm drive mechanism 4a includes a motor for driving each joint of the second robotic arm 4 and an encoder for detecting the rotation angle of each joint of the second robotic arm 4.

[0056] Processing circuit 11b performs calculations, i.e., inverse kinematics calculations, to convert path information Da into motion quantities such as rotation angles and rotational speeds of each joint of the first robotic arm 3. Furthermore, processing circuit 11b outputs control signals Sk1 based on the outputs D1 from each encoder of the arm drive mechanism 3a, so that the actual motion quantities such as rotation angles and rotational speeds of each joint become the calculation results described above. Control signals Sk1 control the drive of the motor of the arm drive mechanism 3a.

[0057] Similarly, processing circuit 11b performs calculations to convert the path information Db into motion quantities such as rotation angles and rotational speeds of each joint of the second robotic arm 4, i.e., inverse kinematics calculations. Furthermore, processing circuit 11b outputs control signals Sk2 based on the outputs D2 from each encoder of the arm drive mechanism 4a, so that the actual rotation angles and rotational speeds of each joint become the calculation results described above. Control signals Sk2 control the drive of the motor of the arm drive mechanism 4a.

[0058] Here, the processing circuit 11b detects the position and orientation of the workpiece W during printing based on the imaging results of the imaging device 7a in the imaging unit 7. Furthermore, the processing circuit 11b corrects the control signal Sk2 during printing based on the detection results and path information Db, reducing the difference between the detection results and the position and orientation represented by the path information Db. The position and orientation of the workpiece W are obtained, for example, by converting the position and orientation of the workpiece W within the image captured by the imaging device 7a from the imaging coordinate system to a universal coordinate system. Furthermore, the position and orientation of the workpiece W in the imaging coordinate system are calculated, for example, based on the positions of feature points of the workpiece W within the captured image and the shape information of the workpiece W. Additionally, the detection of the position and orientation of the workpiece W obtained based on the imaging results of the imaging device 7a can be performed by either the image processing circuit included in the imaging device 7a or by the computer 13.

[0059] Furthermore, the processing circuit 11b generates a signal D3 based on the output D1 of at least one of the plurality of encoders from the arm drive mechanism 3a. For example, the processing circuit 11b generates a trigger signal as signal D3 that includes a timing pulse from the output D1 of one of the plurality of encoders reaching a predetermined value.

[0060] The control module 12 is a circuit that controls the ink ejection action in the liquid ejection unit 5 based on the signal D3 output from the controller 11 and the printing data from the computer 13. The control module 12 includes a timing signal generation circuit 12a, a power supply circuit 12b, a control circuit 12c, and a drive signal generation circuit 12d.

[0061] The timing signal generation circuit 12a generates a timing signal PTS based on signal D3. The timing signal generation circuit 12a is, for example, composed of a timer that starts generating the timing signal PTS based on the detection of signal D3.

[0062] The power supply circuit 12b receives power from a commercial power supply not shown and generates various predetermined potentials. These potentials are appropriately supplied to the control module 12 and various parts of the liquid ejection unit 5. For example, the power supply circuit 12b generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection unit 5. Furthermore, the power supply potential VHV is supplied to the drive signal generation circuit 12d.

[0063] The control circuit 12c generates a control signal SI, a waveform specification signal dCom, a latch signal LAT, a clock signal CLK, and a switching signal CNG based on the timing signal PTS. These signals are synchronized with the timing signal PTS. The waveform specification signal dCom is input to the drive signal generation circuit 12d, while the other signals are input to the switching circuit 5d of the liquid ejection unit 5.

[0064] The control signal SI is a digital signal used to specify the operating state of the drive element of the head 5a of the liquid ejection unit 5. Specifically, the control signal SI specifies whether to supply the drive signal Com (described later) to the drive element. This specification, for example, specifies whether ink is ejected from the nozzle corresponding to the drive element, or specifies the amount of ink ejected from the nozzle. The waveform specification signal dCom is a digital signal used to specify the waveform of the drive signal Com. The latch signal LAT and the exchange signal CNG, used in conjunction with the control signal SI, specify the drive timing of the drive element, thereby specifying the ejection timing of ink from the nozzle. The clock signal CLK is a clock signal that serves as a reference synchronized with the timing signal PTS.

[0065] The control circuit 12c described above includes, for example, one or more processors such as CPUs (Central Processing Units). Alternatively, the control circuit 12c may replace a CPU or include programmable logic devices such as FPGAs (field-programmable gate arrays) in addition to a CPU.

[0066] The drive signal generation circuit 12d is a circuit that generates drive signals Com for driving the drive elements of the head 5a of the liquid ejection unit 5. Specifically, the drive signal generation circuit 12d includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 12d, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 12c from a digital signal to an analog signal, and the amplification circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 12b, thereby generating the drive signal Com. Here, the waveform signal of the waveform contained in the drive signal Com that is actually supplied to the drive element is the drive pulse PD. The drive pulse PD is supplied to the drive element from the drive signal generation circuit 12d via the switching circuit 5d of the liquid ejection unit 5. The switching circuit 5d switches whether to supply at least a portion of the waveform contained in the drive signal Com as the drive pulse PD based on the control signal SI.

[0067] Computer 13 has the function of supplying path information Da and path information Db to controller 11, and the function of supplying printing data to control module 12. Additionally, the aforementioned imaging device 7a can also be connected to controller 11 via computer 13. In this case, computer 13 can either input the imaging results of imaging device 7a directly to controller 11, or calculate the position and orientation of workpiece W based on the imaging results of imaging device 7a, and input the information representing the calculation results to controller 11.

[0068] 1-3. Structure of the first robotic arm

[0069] Figure 3 This is a perspective view of the first robotic arm 3. The structure of the first robotic arm 3 will be described below. Regarding the structure of the second robotic arm 4, since it is the same as the first robotic arm 3 except for the different end effector, its description is omitted. However, it is also possible for the structures of the first robotic arm 3 and the second robotic arm 4 to differ from each other, as already described. This will be appropriately explained in sections 1-5, etc., later in the text.

[0070] like Figure 3 As shown, the first robotic arm 3 has a base 310 and an arm 320, which serve as an example of a "first base".

[0071] The base 310 is a platform that supports the arm 320. Figure 3 In the example shown, the base 310 is mounted in the Z direction relative to the surface 2a of the base 2 described above, and is fixed by screws or the like.

[0072] Arm 320 is a six-axis robotic arm having a base end mounted on a base 310 and a tip that allows the position and orientation to change three-dimensionally relative to the base end. Specifically, arm 320 has arms 321, 322, 323, 324, 325, and 326, which are connected in this order.

[0073] Arm 321 is connected to base 310 via joint 330_1, allowing it to rotate about rotation axis O1. Arm 322 is connected to arm 321 via joint 330_2, allowing it to rotate about rotation axis O2. Arm 323 is connected to arm 322 via joint 330_3, allowing it to rotate about rotation axis O3. Arm 324 is connected to arm 323 via joint 330_4, allowing it to rotate about rotation axis O4. Arm 325 is connected to arm 324 via joint 330_5, allowing it to rotate about rotation axis O5. Arm 326 is connected to arm 325 via joint 330_6, allowing it to rotate about rotation axis O6.

[0074] Each of the joints 330_1 to 330_6 is a mechanism that allows one of two adjacent components of the base 310 and arms 321 to 326 to be rotatably connected relative to the other. Although in Figure 3 Although not illustrated, each of the joints 330_1 to 330_6 is provided with a drive mechanism that rotates one of the two adjacent components relative to the other. This drive mechanism may include, for example, a motor that generates a driving force for the rotation, a reducer that reduces and outputs the driving force, and a rotary encoder that detects the amount of motion, such as the angle of rotation. Furthermore, the assembly of this drive mechanism for joints 330_1 to 330_6 corresponds to the aforementioned... Figure 2 The arm drive mechanism 3a shown is illustrated.

[0075] Rotation axis O1 is perpendicular to the surface 2a to which the base 310 is fixed. Rotation axis O2 is perpendicular to rotation axis O1. Rotation axis O3 is parallel to rotation axis O2. Rotation axis O4 is perpendicular to rotation axis O3. Rotation axis O5 is perpendicular to rotation axis O4. Rotation axis O6 is perpendicular to rotation axis O5.

[0076] Furthermore, for these rotating axes, "perpendicular" includes not only the case where the angle between the two rotating axes is strictly 90°, but also the case where the angle between the two rotating axes deviates from 90° within a range of approximately ±5°. Similarly, "parallel" includes not only the case where the two rotating axes are strictly parallel, but also the case where one of the two rotating axes is tilted relative to the other within a range of approximately ±5°.

[0077] On the topmost arm of the above-mentioned arm 320, namely arm 326, a liquid ejection unit 5 is installed as an end effector.

[0078] 1-4. Structure of the liquid ejection unit

[0079] Figure 4 This is a perspective view showing the general structure of the liquid ejection unit 5. The following description appropriately uses intersecting a-axis, b-axis, and c-axis. Furthermore, 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 opposite directions along the b-axis are referred to as the b1 direction and the b2 direction. Furthermore, the opposite directions along the c-axis are referred to as the c1 direction and the c2 direction.

[0080] Here, the a-axis, b-axis, and c-axis are the coordinate axes of the tool coordinate system set in the liquid ejection unit 5, and their relative positions and orientations with the X-axis, Y-axis, and Z-axis described above change according to the movements of the first robotic arm 3 described above. Figure 4 In the example shown, the c-axis is parallel to the sixth rotation axis O6 described above. Furthermore, while the a-axis, b-axis, and c-axis are typically orthogonal to each other, this is not a limitation; for example, they can intersect at angles within the range of 80° to 100°. Additionally, the tool coordinate system is established to correspond with the base coordinate system described above through calibration. Moreover, the tool coordinate system is set, for example, with the center of the nozzle surface F, described later, as the reference (tool center point).

[0081] As mentioned above, the liquid ejection unit 5 includes a head 5a, a pressure regulating valve 5b, and a pre-hardening light source 5c. These are... Figure 4 The support 5e, indicated by a double-dotted line, is also supported. Additionally, although in Figure 4 In the example shown, the liquid ejection unit 5 has one of each of the head 5a and the pressure regulating valve 5b, but this number is not limited to one. Figure 4 The example shown can also include more than two. Furthermore, the position of the pressure regulating valve 5b is not limited to arm 326; for example, it can be other arms, or it can be a position fixed relative to the base 310.

[0082] The support 5e is made of, for example, a metallic material and is essentially a rigid body. Furthermore, although in Figure 4 The support body 5e is a flat box shape, but the shape of the support body 5e is not particularly limited but can be any shape.

[0083] The aforementioned support 5e is mounted on the arm 326 described above. Thus, the head 5a, pressure regulating valve 5b, and pre-curing light source 5c are integrally supported on the arm 326 by the support 5e. Therefore, the relative position of each of the head 5a, pressure regulating valve 5b, and pre-curing light source 5c relative to the arm 326 is fixed.

[0084] The head 5a has a nozzle face F and multiple nozzles N that open on the nozzle face F. Figure 4 In the example shown, the normal direction of the nozzle surface F is the c2 direction, and the plurality of nozzles N are divided into a first nozzle column La and a second nozzle column Lb arranged at intervals along the a-axis. Each of the first nozzle column La and the second nozzle column Lb is a collection of a plurality of nozzles N arranged in a straight line along the b-axis. Here, the elements associated with each nozzle N in the first nozzle column La and the elements associated with each nozzle N in the second nozzle column Lb in the first 5a are structurally approximately symmetrical with each other along the a-axis.

[0085] However, the positions of the multiple nozzles N in the first nozzle column La and the multiple nozzles N in the second nozzle column Lb along the b-axis can be either consistent or different. Furthermore, elements associated with each nozzle N in either the first nozzle column La or the second nozzle column Lb can be omitted. In the following, a structure in which the multiple nozzles N in the first nozzle column La and the multiple nozzles N in the second nozzle column Lb are consistent along the b-axis will be illustrated.

[0086] Although not illustrated, the head 5a has a piezoelectric element as a driving element and a cavity for collecting ink for each nozzle N. Here, the piezoelectric element causes ink to be ejected from the nozzle corresponding to the cavity by changing the pressure in the cavity corresponding to the piezoelectric element. Such a head 5a can be obtained, for example, by bonding together multiple substrates, such as silicon substrates, that have been appropriately processed by etching or the like using an adhesive. Alternatively, a heater that heats the ink within the cavity can be used instead of the piezoelectric element as the driving element for ejecting ink from the nozzle.

[0087] exist Figure 4 In the example shown, the pressure regulating valve 5b is located in the c1 direction relative to the head 5a. The pre-hardening light source 5c is located in the a2 direction relative to the head 5a.

[0088] The pressure regulating valve 5b is connected to the auxiliary tank 6c via the supply pipe 6d of the ink supply unit 6 described above. The pressure regulating valve 5b is a valve mechanism that opens and closes according to the pressure of the ink in the head 5a. Through this opening and closing, even if the positional relationship between the head 5a and the auxiliary tank 6c changes, the pressure of the ink in the head 5a is maintained at a negative pressure within a predetermined range. Therefore, the meniscus of the ink formed in the nozzle N of the head 5a is stabilized. As a result, air bubbles are prevented from entering the nozzle N or ink overflowing from the nozzle N. Furthermore, the ink from the pressure regulating valve 5b is appropriately distributed to multiple parts of the head 5a via branch channels (not shown).

[0089] The pre-curing light source 5c emits energy such as light, heat, electron beams, or radiation to partially cure or semi-cure the ink on the workpiece W. "Partial curing" refers to a state where curing occurs locally rather than completely. Similarly, "semi-curing" refers to a state where curing occurs locally rather than completely. The pre-curing light source 5c, like the light source 10b of the curing unit 10 described above, is composed, for example, of a light-emitting element such as an LED (light emitting diode) that emits ultraviolet light. Furthermore, the pre-curing light source 5c may also have optical components such as lenses for adjusting the direction or range of energy emission. The pre-curing light source 5c can be provided only as needed and may be omitted. Alternatively, the ink on the workpiece W can be completely cured using the pre-curing light source 5c.

[0090] 1-5. Configuration of Hardening Unit and Maintenance Unit

[0091] Figure 5 This is a top view of the three-dimensional printing apparatus 1 according to the first embodiment. Figure 5 The image shows a stereolithography printing apparatus 1 when viewed in the Z2 direction.

[0092] As described above, the first robotic arm 3 has a base 310, which is fixed to the base 2 as an example of a "first base," and an arm 320, with a head 5a mounted at the top of the arm 320. On the other hand, as... Figure 5 As shown, the second robotic arm 4 has a base 410, which is fixed to the base 2 as an example of a "second base", and an arm 420, and a gripper mechanism 40 for supporting the workpiece W is mounted at the top of the arm 420. In addition, the base 410 is mounted in the Z direction relative to the surface 2a of the base 2, just like the base 310, and is fixed by screws or the like.

[0093] When viewed from above at base 2, the positions of base 310 and base 410 along the X-axis are different, with base 310 located closer to the X1 direction than base 410. Therefore, when viewed from above at base 2, the imaginary line segment LV connecting base 310 and base 410 extends primarily along the X-axis. Furthermore, the imaginary line segment LV can be used to connect any position of base 310 to any position of base 410 when viewed from above at base 2. Figure 5 In the example shown, the imaginary line segment LV passes through the first axis of rotation of each of the first robotic arm 3 and the second robotic arm 4, which is the joint closest to the base 2.

[0094] However, in Figure 5In the example shown, the positions of base 310 and base 410 along the Y-axis are slightly different, with base 310 located closer to the Y1 direction than base 410. Therefore, when viewed from above the base 2, the imaginary line segment LV is slightly tilted relative to the X-axis. Alternatively, in this embodiment, the imaginary line segment LV can also be considered parallel to the X-axis when viewed from above the base 2. Furthermore, the imaginary line segment LV can also be made parallel to the X-axis when viewed from above the base 2.

[0095] A maintenance unit 8 is disposed at a position in the Y1 direction relative to the imaginary line segment LV. On the other hand, an ink supply unit 6, an imaging unit 7, a maintenance unit 8, and a mounting section 9 are disposed at a position in the Y2 direction relative to the imaginary line segment LV.

[0096] Therefore, when viewed from above the base 2, the imaginary line segment LV passes between the hardening unit 10 and the maintenance unit 8. Furthermore, when viewed from above the base 2, the imaginary line segment LV passes through the imaging range RI. Therefore, it is possible to photograph objects located near the imaginary line segment LV using the imaging unit 7.

[0097] Furthermore, the maintenance unit 8 is located inside the operating range RR1 of the first robotic arm 3 and outside the operating range RR2 of the second robotic arm 4. Here, since the first robotic arm 3 uses the maintenance unit 8 for maintaining the head 5a, it is necessary to place the maintenance unit 8 inside the operating range RR1 of the first robotic arm 3. On the other hand, since the second robotic arm 4 does not use the maintenance unit 8, it is not necessary to place the maintenance unit 8 inside the operating range RR2 of the second robotic arm 4. Alternatively, if it does not obstruct the movement of the second robotic arm 4, the maintenance unit 8 can also be placed inside the operating range RR2 of the second robotic arm 4.

[0098] Here, the range of motion RR1 is the area inside a circle centered on any part of the base 310 and with a radius equal to the length LR1 of the arm 320, as viewed from above the base 2. The length LR1 is the distance between the two ends of the arm 320 when it extends in a straight line. Similarly, the range of motion RR2 is the area inside a circle centered on any part of the base 410 and with a radius equal to the length LR2 of the arm 420, as viewed from above the base 2. The length LR2 is the distance between the two ends of the arm 420 when it extends in a straight line.

[0099] Lengths LR1 and LR2 can be either equal or different. Figure 5In the example shown, the length LR1 of the arm 320 of the first robotic arm 3 is shorter than the length LR2 of the arm 420 of the second robotic arm 4. This is to reduce the vibration of the first robotic arm 3 during operation while increasing the degree of freedom of gripping the workpiece W by the second robotic arm 4. Here, from the viewpoint of reducing the vibration of the first robotic arm 3 during operation, it is preferable that the load-bearing weight of the first robotic arm 3 is larger than that of the second robotic arm 4.

[0100] Furthermore, the maintenance unit 8 is located outside the shooting range RI. This is because photographing the maintenance unit 8 using the shooting device 7a would complicate the processing of the shooting results using the shooting device 7a, and this situation must be prevented. Additionally, the maintenance unit 8 is located outside the illumination range RL of the illumination unit 7b. This is to prevent the light from the illumination unit 7b from being blocked by the head 5a during the maintenance process performed by the maintenance unit 8. Furthermore, in this embodiment, the illumination range RL refers to the range located in the Y1 direction relative to the illumination unit 7b.

[0101] Furthermore, although the mounting section 9 is located on the same side as the maintenance unit 8 relative to the imaginary line segment LV when viewed from above the base 2, it is positioned outside the shooting range RI. This is not only because it is unnecessary to photograph the workpiece W located on the mounting section 9 using the shooting device 7a, but also because photographing it would complicate the processing of the photographing results using the shooting device 7a, and therefore this situation must be prevented.

[0102] Furthermore, when viewed from above the base 2, each of the hardening unit 10 and the maintenance unit 8 is located between a first straight line LS1 that passes through the base 310 of the first robotic arm 3 and is orthogonal to the imaginary line segment LV, and a second straight line LS2 that passes through the base 410 of the second robotic arm 4 and is orthogonal to the imaginary line segment LV. This is to achieve miniaturization of the stereolithography printing device 1.

[0103] 1-6. Operation of the 3D printing apparatus

[0104] Figure 6 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to the first embodiment. Figure 6 As shown, the stereoscopic printing apparatus 1 sequentially performs the material feeding step S10, the information acquisition step S20, the adjustment step S30, the first printing step S40, the avoidance step S50, the movement step S60, the second printing step S70, the post-processing step S80, and the material removal step S90.

[0105] Here, the material supply step S10 includes a holding step S11. Furthermore, the post-processing step S80 includes a hardening step S81 and a maintenance step S82. The hardening step S81 includes a first hardening step S81a and a second hardening step S81b. Each step will be described sequentially below.

[0106] 1-6-1. Material supply step S10

[0107] Figure 7 This is a diagram used to illustrate the material feeding step S10. In the material feeding step S10, firstly, the holding step S11 is performed. In the holding step S11, as... Figure 7 As shown by solid lines, with the second robotic arm 4 bringing the gripper mechanism 40 close to the mounting section 9, the gripper mechanism 40 holds the workpiece W located on the mounting section 9. Thus, the gripper mechanism 40 receives the workpiece W from the mounting section 9. Thereafter, as... Figure 7 As shown by the double-dotted line, the second robotic arm 4 moves the workpiece W from the outside to the inside of the shooting range RI.

[0108] In this step, the movement state of the first robotic arm 3 is not particularly limited, but can be any movement state. Furthermore, in this step, although the movement state of each of the imaging unit 7 and the hardening unit 10 is not particularly limited, it is preferable that the illumination part 7b of the imaging unit 7 or the light source 10b of the hardening unit 10 be turned off, depending on the position or posture of the head 5a, when the head 5a is not covered by the maintenance unit 8.

[0109] 1-6-2. Information Acquisition Step S20

[0110] Information acquisition step S20 is as follows: in the second robotic arm 4, such as... Figure 7 In the state where the workpiece W is held as shown by the double-dotted line, the controller 11 obtains information related to the relative position of the workpiece W with respect to the base 2 based on the imaging results of the imaging device 7a.

[0111] In this step, the illumination unit 7b is turned on. Therefore, from the viewpoint of preventing the ink near the nozzle N from hardening or curing due to the light from the illumination unit 7b, it is preferable that the first robotic arm 3 positions the nozzle surface F outside the illumination range RL of the illumination unit 7b, or faces the nozzle surface F toward a direction that becomes the backlight from the illumination unit 7b. For the same viewpoint, in this step, it is preferable that the nozzle N is covered by the maintenance unit 8.

[0112] Furthermore, in this step, from the viewpoint of improving the accuracy of the position-related information obtained based on the imaging results from the imaging device 7a, it is preferable that the head 5a is located outside the imaging range RI. Here, in this step, at least one of the first robotic arm 3 and the second robotic arm 4 may have a portion located inside the imaging range RI. However, in this case, from the viewpoint of improving the accuracy of the position-related information, it is preferable that the color of the workpiece W is different from the color of that portion of the first robotic arm 3 and the second robotic arm 4. For example, by painting that portion of the first robotic arm 3 and the second robotic arm 4 a different color from the workpiece W, the contrast between the workpiece W and the portion that forms its background in the image obtained by the imaging device 7a can be improved. This makes processing the imaging results in the processing circuit 11b easier, thus improving the accuracy of the position-related information. Additionally, if that portion is set to black, it is easier to maintain the contrast in the image even when the color differs due to the workpiece W.

[0113] 1-6-3. Adjustment step S30

[0114] In adjustment step S30, controller 11 controls the movement of the second robotic arm 4 based on the information obtained in information acquisition step S20 to adjust the position of the workpiece W located inside the shooting range RI.

[0115] The adjusted position and orientation of the workpiece W implemented in this step is the first state, and is the position and orientation of the workpiece W during the execution of the first printing step S40. Here, when viewed from above the base 2, the position of the workpiece W adjusted in this step is closer to the imaginary line segment LV than the position of the workpiece W during the execution of the previously described holding step S11. Furthermore, when viewed from above the base 2, the position of the workpiece W adjusted in this step is closer to the imaginary line segment LV than the positions during the execution of the hardening step S81 and the maintenance step S82.

[0116] 1-6-4. First printing step S40

[0117] Figure 8 This diagram illustrates the movement of the first robotic arm 3 in the first printing step S40. In the first printing step S40, as... Figure 8 As shown, with the second robotic arm 4 fixing the position and orientation of the workpiece W in the first state, while the first robotic arm 3 moves the head 5a and the workpiece W relative to each other within the shooting range RI, the head 5a sprays ink onto the workpiece W. Figure 8In the example shown, the first robotic arm 3 moves the head 5a along the long axis of the workpiece W. Furthermore, the orientation of the workpiece W in the first printing step S40 is not specifically limited, but can be any orientation.

[0118] Thus, in this step, the first robotic arm 3 operates while the second robotic arm 4 remains stationary. This prevents vibration of the workpiece W. Furthermore, this vibration is easily generated because the workpiece W is held in a detachable manner by the gripper mechanism 40, and becomes significant when the second robotic arm 4 operates in the first printing step, causing the ink droplet spray position to shift and resulting in image quality degradation. Additionally, if the rigidity of the workpiece W is reduced due to its material or shape, the vibration of the workpiece W also becomes significant, similarly affecting image quality. In contrast, the head 5a mounted on the first robotic arm is not held by a gripper mechanism, making it less prone to vibration compared to the workpiece W. Therefore, in this step, by operating the first robotic arm 3 while the second robotic arm 4 remains stationary, the image quality degradation caused by such vibration can be suppressed. Here, from the viewpoint of reducing the meandering movement path of the head 5a, it is preferable to minimize the number of joints in the first robotic arm 3 that perform the action in this step. Furthermore, it is preferable to perform the action of the first robotic arm 3 through the movement of joints on three mutually parallel rotation axes. Figure 8 In the example shown, the three rotation axes are rotation axis O2, rotation axis O3, and rotation axis O5.

[0119] In this step, from the viewpoint of preventing the ink near the nozzle N from hardening or curing due to light from the illumination section 7b, it is preferable to turn off the illumination section 7b.

[0120] Figure 9 This diagram illustrates the printing area of ​​the workpiece W in the first printing step S40. (See diagram below.) Figure 9 As shown, in this step, while the first robotic arm 3 scans the first region RP1 of the workpiece W along different regions RP1 and RP2, the head 5a sprays ink into the first region RP1. Figure 9 In the example shown, a portion of the first region RP1 and the second region RP2 overlap. Alternatively, the first region RP1 and the second region RP2 can be made not to overlap. For example, the first region RP1 and the second region RP2 can also be in a face-to-face relationship.

[0121] In this step, the pre-curing light source 5c can also be illuminated. In this case, the ink on the workpiece W can be pre-cured. Alternatively, after this step, without the ink being ejected from the head 5a, the pre-curing light source 5c can be illuminated while the first robotic arm 3 scans along the first region RP1.

[0122] 1-6-5. Avoidance Step S50

[0123] Figure 10 This is a diagram used to illustrate the avoidance step S50. In the avoidance step S50, as... Figure 10 As shown, the distance between the head 5a and the workpiece W caused by the first robotic arm 3 is increased compared to the execution of the first printing step S40. Figure 10 The example shown illustrates a state where the head 5a is covered by the maintenance unit 8. Alternatively, in this step, the head 5a may not be covered by the maintenance unit 8. However, in this case, it is preferable to extinguish the illumination section 7b of the imaging unit 7 or the light source 10b of the hardening unit 10, depending on the position or orientation of the head 5a.

[0124] 1-6-6. Moving step S60

[0125] Figure 11 This diagram illustrates the movement step S60. In movement step S60, the second robotic arm 4 changes the position and orientation of the workpiece W from a first state to a second state that differs from the first state. Figure 11 In the example shown, the first state is Figure 11 The state shown by the double-dotted line is the second state. Figure 11 The state is shown by a solid line. This second state is the position and orientation of the workpiece W during the execution of the second printing step S70. Alternatively, this step may include adjusting the position of the workpiece W in the same way as the adjustment step S30 described above.

[0126] 1-6-7. Second printing step S70

[0127] In the second printing step S70, as Figure 11 As shown, except for printing on the second region RP2, printing is performed in the same manner as the first printing step S40 described above. Here, in the second printing step S70, with the second robotic arm 4 fixing the position and orientation of the workpiece W in the second state, while the first robotic arm 3 moves the head 5a and the workpiece W relative to each other within the shooting range RI, the head 5a sprays ink onto the workpiece W. Furthermore, the operation of the first robotic arm 3 in this step is the same as the operation of the first robotic arm 3 in the first printing step S40 described above.

[0128] In this step, the pre-curing light source 5c can also be illuminated. In this case, the ink on the workpiece W can be pre-cured. Alternatively, after this step, without the ink being ejected from the head 5a, the pre-curing light source 5c can be illuminated while the first robotic arm 3 scans along the second region RP2.

[0129] 1-6-8. Post-processing step S80

[0130] Figure 12 This is a diagram used to illustrate the hardening step S81 and the maintenance step S82. As described, the post-processing step S80 includes the hardening step S81 and the maintenance step S82.

[0131] In hardening step S81, as Figure 12 As shown, with the second robotic arm 4 bringing the workpiece W close to the hardening unit 10, the hardening unit 10 irradiates energy onto the ink on the workpiece W. Here, in this embodiment, as described, the hardening step S81 includes a first hardening step S81a and a second hardening step S81b.

[0132] In the first curing step S81a, while the second robotic arm 4 changes the relative position and orientation of the curing unit 10 and the workpiece W, the curing unit 10 irradiates energy onto the ink in the first region RP1. In the second curing step S81b, while the second robotic arm 4 changes the relative position and orientation of the curing unit 10 and the workpiece W, the curing unit 10 irradiates energy onto the ink in the second region RP2. In these steps, as long as energy can be irradiated onto the ink, problems caused by vibration of the workpiece W, as seen in the first printing step S40 or the second printing step S70, will not occur. Here, it is preferable that the first curing step S81a and the second curing step S81b are performed in this order. This is because by reducing the time difference between the ink in the first region RP1 and the ink in the second region RP2 after they are respectively ejected and before they are irradiated with energy, the difference in image quality between the first region RP1 and the second region RP2 can be reduced. Alternatively, the first curing step S81a and the second curing step S81b can also be performed substantially simultaneously.

[0133] In maintenance step S82, such as Figure 12As shown, with the head 5a brought close to the maintenance unit 8 by the first robotic arm 3, maintenance of the head 5a is performed by the maintenance unit 8. Maintenance includes covering the nozzle and nozzle surface with the cover of unit 8a, drawing ink from the nozzle of the head 5a while the nozzle and nozzle surface are covered by the cover, cleaning the nozzle surface of the head 5a with the wiper of unit 8a, and printing an inspection pattern from the head 5a in unit 8b. However, if the illumination unit 7b or the hardening unit 10 is illuminated during the execution of maintenance step S82, it is preferable that the maintenance is the action of covering the nozzle and nozzle surface with the cover. From the viewpoint of reducing processing time, it is preferable that maintenance step S82 is performed during the execution of the first hardening step S81a.

[0134] Furthermore, from the viewpoint of reducing image bleeding caused by ink flow on the workpiece W by immediately hardening the ink on the workpiece W, it is preferable that the position of the workpiece W during the execution of the hardening step S81 is close to the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70. Therefore, it is preferable that the workpiece movement distance DW is shorter than the head movement distance DH, whereby the workpiece movement distance DW is the distance the workpiece W needs to move from the first printing step S40 or the second printing step S70 to the hardening step S81, and the head movement distance DH is the distance the head 5a needs to move from the first printing step S40 or the second printing step S70 to the maintenance step S82.

[0135] Additionally, the workpiece movement distance DW is the distance between the workpiece W during the execution of the first printing step S40 or the second printing step S70, and the workpiece W during the execution of the hardening step S81, when viewed from above on the base 2. The head movement distance DH is the distance between the head 5a during the execution of the first printing step S40 or the second printing step S70, and the head 5a during the execution of the maintenance step S82, when viewed from above on the base 2.

[0136] 1-6-9. Material removal step S90

[0137] Figure 13 This is a diagram used to illustrate the material removal step S90. In the material removal step S90, firstly, as... Figure 13 As shown, the workpiece W is moved to the mounting section 9 by the second robotic arm 4. In this state, the workpiece W is detached by the gripper mechanism 40, thereby placing the printed workpiece W onto the mounting section 9. The printed workpiece W placed on the mounting section 9 can be removed to the outside of the housing 20 by the user, for example.

[0138] In this step, the movement state of the first robotic arm 3 is not particularly limited, but can be any movement state. Furthermore, in this step, the movement state of each of the imaging unit 7 and the hardening unit 10 is not particularly limited, but if the head 5a is not covered by the maintenance unit 8, it is preferable to turn off the illumination part 7b of the imaging unit 7 or the light source 10b of the hardening unit 10, depending on the position or orientation of the head 5a. Alternatively, maintenance step S82 can also be performed in this step.

[0139] As described above, the stereoscopic printing apparatus 1 prints on a stereoscopic workpiece W. Here, as previously mentioned, the stereoscopic printing apparatus 1 includes an imaging device 7a, a first robotic arm 3, and a second robotic arm 4. The imaging device 7a is fixed to the base 2 and images an object located inside the imaging range RI. The first robotic arm 3 supports a head 5a having a nozzle N that ejects ink, an example of "liquid," and changes the position and orientation of the head 5a. The second robotic arm 4 supports the workpiece W and changes the position and orientation of the workpiece W.

[0140] Furthermore, as described above, the stereoscopic printing apparatus 1 performs a material feeding step S10 and, as an example, a first printing step S40 or a second printing step S70, which is a "printing step". In the material feeding step S10, the second robotic arm 4 moves the workpiece W from the outside to the inside of the shooting range RI. In the first printing step S40 or the second printing step S70, while at least one of the first robotic arm 3 and the second robotic arm 4 moves the head 5a and the workpiece W relative to each other inside the shooting range RI, the head 5a sprays ink onto the workpiece W.

[0141] In the above-described three-dimensional printing apparatus, by using the first robotic arm 3 and the second robotic arm 4, the position and orientation of each of the head 5a and the workpiece W can be changed independently. Therefore, compared to a structure that only changes the position and orientation of one of the head 5a and the workpiece W, the head 5a can approach the workpiece W over a larger range. As a result, even if the workpiece W has various three-dimensional shapes, it can be printed appropriately.

[0142] Based on this, in the first printing step S40 or the second printing step S70, at least one of the first robotic arm 3 and the second robotic arm 4 moves the head 5a and the workpiece W relative to each other within the shooting range RI of the shooting device 7a. Therefore, the position and orientation of the workpiece W during the execution of the first printing step S40 or the second printing step S70 can be detected based on the shooting results of the shooting device 7a. Therefore, even if the support position of the workpiece W implemented by the second robotic arm 4 shifts during the first printing step S40 or the second printing step S70, the movement of at least one of the first robotic arm 3 and the second robotic arm 4 can be controlled based on the shooting results of the shooting device 7a, thereby reducing errors in the relative position and orientation of the head 5a and the workpiece W through correction. According to the above method, compared to the structure in the first printing step S40 or the second printing step S70 where the movement of the first robotic arm 3 and the second robotic arm 4 is controlled without using the shooting results of the shooting device 7a, image quality degradation can be reduced.

[0143] As mentioned above, the second robotic arm 4 has a gripper mechanism 40 that holds the workpiece W in a detachable manner. When the gripper mechanism 40 is used in the second robotic arm, the support position of the workpiece W held by the second robotic arm 4 is prone to deviate from the desired position. Therefore, in this case, the effect of controlling the movement of at least one of the first robotic arm 3 and the second robotic arm 4 based on the imaging results of the imaging device 7a is more significant.

[0144] Furthermore, as mentioned above, each of the first robotic arm 3 and the second robotic arm 4 is a vertical multi-joint robotic arm. Therefore, compared to structures using other mechanisms such as horizontal multi-joint robotic arms, it is possible to make a wide variety of changes to the position and orientation of the head 5a and the workpiece W.

[0145] Here, as mentioned above, it is preferable that the length LR1 of the arm 320 of the first robotic arm 3 is shorter than the length LR2 of the arm 420 of the second robotic arm 4. In this case, it is advantageous to make the vibration of the first robotic arm 3 during operation less than that of the second robotic arm 4. This advantage contributes to improved image quality. Furthermore, by making the length of the arm 420 of the second robotic arm 4 longer than that of the arm 320 of the first robotic arm 3, the range of motion of the second robotic arm 4 can be increased. Therefore, it is possible to perform material feeding or removal of the workpiece W, or to perform processing to harden or cure the ink on the workpiece W, at any location within a wide range.

[0146] Furthermore, as mentioned above, it is preferable that the load-bearing capacity of the first robotic arm 3 is greater than that of the second robotic arm 4. In this case, it is advantageous to make the vibration of the first robotic arm 3 during operation less than that of the second robotic arm 4. This advantage contributes to improved image quality. In particular, the greater the weight of the end effector of the first robotic arm 3, the more significant the effect obtained by this advantage.

[0147] As described above, the stereoscopic printing apparatus 1 also includes a mounting section 9. The mounting section 9 is positioned outside the imaging range RI and is capable of mounting the workpiece W. The gripper mechanism 40 receives the workpiece W from the mounting section 9. Thus, since the mounting section 9 is positioned outside the imaging range RI of the imaging device 7a, changes in the imaging conditions of the imaging device 7a due to the presence or absence of the workpiece W on the mounting section 9 are prevented. Therefore, compared to a structure where the mounting section 9 is positioned inside the imaging range RI, the processing of the imaging results using the imaging device 7a can be simplified. Furthermore, although this embodiment illustrates a structure in which the mounting section 9 is used for both the supply and removal of the workpiece W, it is not limited to this structure. For example, the mounting section 9 may be used solely for supplying the workpiece. In this case, for example, a table or conveyor belt, which can mount the workpiece W, may be provided separately from the mounting section 9.

[0148] Furthermore, as described above, the stereolithography printing apparatus 1 performs an information acquisition step S20 between the material feeding step S10 and the first printing step S40 or the second printing step S70. In the information acquisition step S20, information related to the relative position of the workpiece W relative to the base 2 is acquired based on the imaging results of the imaging device 7a. Therefore, the position of the workpiece W after the material feeding step S10 can be detected based on the information acquired in the information acquisition step S20, and the adjustment step S30, as well as the first printing step S40 or the second printing step S70, can be performed based on the detected position.

[0149] Here, as mentioned above, in the information acquisition step S20, the head 5a is located outside the shooting range RI. Therefore, in the information acquisition step S20, it is not necessary to consider the presence of the head 5a in order to obtain information related to the relative position of the workpiece W with respect to the base 2. As a result, compared to a structure where the head 5a is located inside the shooting range RI of the shooting device 7a, the processing in the information acquisition step S20 can be simplified, or the accuracy of the information acquired in the information acquisition step S20 can be improved.

[0150] Furthermore, as described above, the stereoscopic printing apparatus 1 also includes a maintenance unit 8 that covers the nozzle N. The maintenance unit 8 is located outside the imaging range RI. Therefore, since the maintenance unit 8 is not visible to the imaging device 7a, the processing of the imaging results using the imaging device 7a can be simplified. Moreover, in the information acquisition step S20, the nozzle N is covered by the maintenance unit 8. Therefore, hardening or curing of the ink near the nozzle N caused by the illumination used by the imaging device 7a for imaging can be prevented.

[0151] Here, as mentioned above, the maintenance unit 8 is located inside the operating range RR1 of the first robotic arm 3 and outside the operating range RR2 of the second robotic arm 4. Therefore, the maintenance unit 8 can be prevented from becoming an obstacle to the movement of the second robotic arm 4. Furthermore, it has the advantage of easily preventing the ink near the nozzle N from hardening or curing due to the energy from the hardening unit 10 during the execution of the hardening step S81.

[0152] Furthermore, as described above, the stereoscopic printing apparatus 1 also performs an adjustment step S30 between the information acquisition step S20 and the first printing step S40 or the second printing step S70. In the adjustment step S30, the position of the workpiece W located inside the imaging range RI is adjusted. Here, in the adjustment step S30, the movement of the second robotic arm 4 is controlled based on the information acquired in the information acquisition step S20. Therefore, even if the support position of the workpiece W implemented by the second robotic arm 4 deviates from the desired position, the deviation can be corrected. Alternatively, the movement step S60 described above can also include the same processing as the adjustment step S30.

[0153] Furthermore, as described above, the stereoscopic printing apparatus 1 also includes an illumination unit 7b that illuminates the inner side of the imaging range RI. Here, in the information acquisition step S20, the illumination unit 7b is turned on. Therefore, in the information acquisition step S20, since the illumination by the illumination unit 7b improves the contrast of the workpiece W, the accuracy of the information obtained in the information acquisition step S20 can be improved. Conversely, in the first printing step S40 or the second printing step S70, the illumination unit 7b is turned off. Therefore, in the first printing step S40 or the second printing step S70, hardening or curing of the ink near the nozzle N caused by the illumination of the illumination unit 7b can be prevented.

[0154] Here, as mentioned above, the maintenance unit 8 is located outside the illumination range RL of the illumination unit 7b. Therefore, it is possible to prevent the ink near the nozzle N from hardening or curing due to the illumination from the illumination unit 7b.

[0155] Furthermore, as mentioned above, the head 5a has a nozzle surface F on which the nozzle N is provided. When the illumination unit 7b is lit, the nozzle surface F is located outside the illumination range RL of the illumination unit 7b, or facing a direction that becomes the backlight area from the light from the illumination unit 7b. Therefore, it is possible to prevent the ink near the nozzle N from hardening or curing due to the illumination from the illumination unit 7b.

[0156] Here, as mentioned above, in the information acquisition step S20, it is preferable that at least a portion of the color of the first robotic arm 3 located inside the shooting range RI is different from the color of the workpiece W. In this case, in the information acquisition step S20, since the contrast of the workpiece W is improved by the illumination from the illumination unit 7b, the accuracy of the information obtained in the information acquisition step S20 can be improved.

[0157] Similarly, in the information acquisition step S20, preferably, at least a portion of the second robotic arm 4 located inside the shooting range RI has a different color than the workpiece W. In this case, in the information acquisition step S20, since the illumination from the illumination unit 7b improves the contrast of the workpiece W, the accuracy of the information obtained in the information acquisition step S20 can be improved.

[0158] Furthermore, as mentioned above, the first robotic arm 3 has a base 310 as an example of a "first base" fixed to the base 2. Similarly, the second robotic arm 4 has a base 410 as an example of a "second base" fixed to the base 2. Here, when viewed from above the base 2, the imaginary line segment LV connecting the base 310 and the base 410 passes through the shooting range RI. Therefore, compared to the case where the imaginary line segment LV does not pass through the shooting range RI when viewed from above the base 2, the degrees of freedom of position and orientation of the workpiece W and each of the heads 5a within the shooting range RI can be increased.

[0159] As mentioned above, the mounting direction of the base 310 of the first robotic arm 3 and the base 410 of the second robotic arm 4 relative to the base 2 is not limited to the example of this embodiment, but can be appropriately modified. For example, one or both of the first robotic arm 3 and the second robotic arm 4 can be fixed in such a way that they are suspended from a ceiling or beam provided along the X or Y direction, or one or both of the first robotic arm 3 and the second robotic arm 4 can be fixed to a wall or the like provided along the Z direction.

[0160] Here, the "top view of base 2" will be explained. When the base 310 of the first robotic arm 3 and the base 410 of the second robotic arm 4 are fixed relative to base 2 in the same mounting direction as in this embodiment, the "top view of base 2" refers to the state when viewed along this mounting direction. For example, in this embodiment, this mounting direction is the Z direction, and the "top view of base 2" refers to the state when viewed in the Z direction. On the other hand, when the base 310 of the first robotic arm 3 and the base 410 of the second robotic arm 4 are fixed relative to base 2 in different mounting directions than in this embodiment, the "top view of base 2" refers to the state when viewed along the mounting direction of either the first robotic arm 3 or the second robotic arm 4.

[0161] Furthermore, as mentioned above, when the ink ejected from head 5a has photocurability, the ink on the workpiece W can be cured by using the curing unit 10, etc., to keep it in the desired position. As a result, printing can be performed on the three-dimensional workpiece W with high precision.

[0162] As described above, the stereoscopic printing apparatus 1 performs the first printing step S40. In the first printing step S40, while the first robotic arm 3 scans the first region RP1 of the workpiece W with its head 5a, the head 5a sprays ink into the first region RP1. Therefore, printing can be performed on the first region RP1 of the workpiece W. Here, in the first printing step S40, the second robotic arm 4 fixes the position and orientation of the workpiece W to a first state. Therefore, vibration of the workpiece W in the first printing step S40 is prevented. As a result, the image quality can be improved compared to a structure in which the second robotic arm 4 operates in the first printing step S40.

[0163] Furthermore, as described above, the stereolithography printing apparatus 1 also includes a curing unit 10. The curing unit 10 is fixed to the base 2 and emits energy to harden or cure the ink from the head 5a. The stereolithography printing apparatus 1 performs a first curing step S81a after the execution of the first printing step S40. In the first curing step S81a, while the second robotic arm 4 changes the relative position and orientation of the curing unit 10 and the workpiece W, the curing unit 10 irradiates energy onto the ink in the first region RP1. Therefore, in the first curing step S81a, the energy from the curing unit 10 can be used to harden or cure the ink ejected onto the workpiece W in the first printing step S40.

[0164] Here, in the first curing step S81a, since the second robotic arm 4 changes the relative position and orientation of the curing unit 10 and the workpiece W, even though the curing unit 10 is fixed on the base 2, energy from the curing unit 10 can be appropriately applied to the ink on the workpiece W. Furthermore, in the first curing step S81a, even if the workpiece W vibrates, the problems encountered during printing will not occur. Moreover, the control precision of the position and orientation of the workpiece W in the first curing step S81a is lower compared to the control precision of the position and orientation of the head 5a in the first printing step S40.

[0165] As described above, preferably, the stereolithography printing apparatus 1 performs a maintenance step S82 during the execution of the first hardening step S81a. In the maintenance step S82, maintenance of the first 5a, performed by the maintenance unit 8, is carried out. Thus, by overlapping at least a portion of the execution period of the hardening step S81 and the execution period of the maintenance step S82, the time required for these steps can be shortened compared to the case where the maintenance step S82 is not performed during the execution of the first hardening step S81a.

[0166] Here, the first hardening step S81a is performed using the second robotic arm 4 without using the first robotic arm 3, while the maintenance step S82 is performed using the first robotic arm 3 without using the second robotic arm 4. Therefore, the maintenance step S82 can be performed during the execution of the first hardening step S81a. Furthermore, since the head 5a is covered by the maintenance unit 8 during the execution of the maintenance step S82, it is also possible to prevent the ink near the nozzle N from hardening or curing due to the energy from the hardening unit 10 in the first hardening step S81a.

[0167] Furthermore, as described above, the 3D printing apparatus 1 performs a movement step S60 after the execution of the first printing step S40. In the movement step S60, the second robotic arm 4 changes the position and orientation of the workpiece W from the first state described above to a second state different from the first state. Therefore, after the execution of the movement step S60, printing can be performed on an area different from the printing area of ​​the workpiece W in the first printing step S40, using the same movements of the first robotic arm 3 as in the first printing step S40. In addition, in the movement step S60, the position adjustment of the workpiece W is performed as needed, similar to the adjustment step S30 described above.

[0168] Here, as described above, the stereoscopic printing apparatus 1 performs the second printing step S70 after the movement step S60. In the second printing step S70, while the first robotic arm 3 scans the workpiece W along a second region RP2 that is different from the first region RP1, the head 5a sprays ink into the second region RP2. Therefore, printing can be performed in the second region of the workpiece W. Here, in the second printing step S70, the second robotic arm 4 fixes the position and orientation of the workpiece W to the second state described above. Therefore, vibration of the workpiece W in the second printing step S70 is prevented. As a result, the image quality can be improved compared to a structure in which the second robotic arm 4 moves in the second printing step S70.

[0169] In this embodiment, as described above, the actions of the first robotic arm 3 in the first printing step S40 and the first robotic arm 3 in the second printing step S70 are identical. Therefore, compared to a situation where the actions of the first robotic arm 3 in these steps differ, the difference in the movement path of the head 5a in these steps can be reduced. This is because by repeatedly performing the same actions with the first robotic arm 3, the reproducibility of the movement path of the head 5a can be improved. Thus, by reducing the difference in the movement path of the head 5a in these steps, the image quality achieved by the first printing step S40 and the second printing step S70 can be improved.

[0170] Here, by utilizing the movement of joints on three parallel rotating axes to make the first robotic arm 3 move, the meandering path of the head 5a can also be reduced.

[0171] Furthermore, as described above, the stereolithography printing apparatus 1 performs a second curing step S81b after the second printing step. In the second curing step S81b, while the second robotic arm 4 changes the relative position and orientation of the curing unit 10 and the workpiece W, the curing unit 10 irradiates energy onto the ink on the second region RP2. Therefore, in the second curing step S81b, the ink sprayed onto the workpiece W in the second printing step S70 can be cured or solidified using the energy from the curing unit 10.

[0172] Here, in the second curing step S81b, since the relative position and orientation of the curing unit 10 and the workpiece W are changed by the second robotic arm 4, even though the curing unit 10 is fixed on the base 2, energy from the curing unit 10 can be appropriately applied to the ink on the workpiece W. Furthermore, in the second curing step S81b, even if the workpiece W vibrates, the problems encountered during printing will not occur. Moreover, the control precision of the position and orientation of the workpiece W in the second curing step S81b is lower compared to the control precision of the position and orientation of the head 5a in the second printing step S70.

[0173] As described above, preferably, the stereolithography printing apparatus 1 performs the maintenance step S82 during the execution of the second hardening step S81b. In the maintenance step S82, maintenance of the first 5a, performed by the maintenance unit 8, is carried out. Thus, by overlapping at least a portion of the execution period of the hardening step S81 and the execution period of the maintenance step S82, the time required for these steps can be shortened compared to the case where the maintenance step S82 is not performed during the execution of the second hardening step S81b.

[0174] Here, the second hardening step S81b is performed using the second robotic arm 4 without using the first robotic arm 3, while the maintenance step S82 is performed using the first robotic arm 3 without using the second robotic arm 4. Therefore, the maintenance step S82 can be performed during the execution of the second hardening step S81b. Furthermore, since the head 5a is covered by the maintenance unit 8 during the execution of the maintenance step S82, it is also possible to prevent the ink near the nozzle N from hardening or curing due to the energy from the hardening unit 10 in the second hardening step S81b.

[0175] As described above, preferably, the stereoscopic printing apparatus 1 performs the first printing step S40, the second printing step S70, the first curing step S81a, and the second curing step S81b sequentially. In this case, the first printing step S40 and the second printing step S70 can be performed continuously. Therefore, it has the advantage of easily reducing the difference in the movement path of the first 5a in the first printing step S40 and the second printing step S70. Furthermore, by performing the first curing step S81a and the second curing step S81b sequentially, compared with the case where they are performed in the reverse order, the time difference between the time after the ink is ejected in each printing step and the time before the energy is irradiated in each curing step can be reduced. As a result, the difference in image quality between the images formed in different printing steps can be reduced. In addition, the first curing step S81a and the second curing step S81b can also be substantially simultaneous.

[0176] Furthermore, as described above, the 3D printing apparatus 1 performs a clearance step S50 between the first printing step S40 and the moving step S60. In the clearance step S50, the first robotic arm 3 increases the distance between its head 5a and the workpiece W compared to when the first printing step S40 is performed. Therefore, it has the advantage that the second robotic arm 4 can easily operate after the clearance step S50 without interfering with the first robotic arm 3. Furthermore, it is also possible to perform head 5a maintenance, etc., at a position where clearance has been achieved compared to when the first printing step S40 is performed, after the clearance step S50 is performed.

[0177] Furthermore, in the stereolithography printing apparatus 1, when viewed from above the base 2, the imaginary line segment LV passes between the hardening unit 10 and the maintenance unit 8. That is, the hardening unit 10 is positioned within one of the two regions divided by the imaginary line segment LV, while the maintenance unit 8 is positioned within the other region. Therefore, interference between the first robotic arm 3 and the second robotic arm 4 can be prevented when the processing performed by the hardening unit 10 and the maintenance unit 8 is performed simultaneously. Specifically, when the first robotic arm 3 and the second robotic arm 4 move from the first printing step S40 or the second printing step S70 to the hardening step S81, the head 5a and the workpiece W move in a direction separating from each other. Therefore, interference between the first robotic arm 3 and the second robotic arm 4 can be prevented after the execution of the first printing step S40 or the second printing step S70. Additionally, in this embodiment, as described above, the hardening step S81 includes a first hardening step S81a and a second hardening step S81b.

[0178] Here, as mentioned above, it is preferable that, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than during the execution of the hardening step S81. The closer the position of the workpiece W is to the imaginary line segment LV, the higher the degree of freedom of movement of the first robotic arm 3 and the second robotic arm 4 during the execution of the first printing step S40 or the second printing step S70. Therefore, by making the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 closer to the imaginary line segment LV than during the execution of the hardening step S81, the degree of freedom of posture of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can be improved.

[0179] For the same reason, as mentioned above, it is preferable that, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than the position of the workpiece W during the execution of the maintenance step S82. In this case, the degree of freedom of the orientation of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can also be improved.

[0180] Furthermore, as mentioned above, in the stereolithography printing apparatus 1, the workpiece movement distance DW is shorter than the head movement distance DH. Additionally, the workpiece movement distance DW is the distance between the workpiece W during the execution of the first printing step S40 or the second printing step S70, and the workpiece W during the execution of the hardening step S81, when viewed from above the base 2. The head movement distance DH is the distance between the head 5a during the execution of the first printing step S40 or the second printing step S70, and the head 5a during the execution of the maintenance step S82, when viewed from above the base 2.

[0181] Thus, by making the workpiece movement distance DW shorter than the head movement distance DH, the transfer from the first printing step S40 or the second printing step S70 to the hardening step S81 can be carried out quickly even without increasing the movement speed of the workpiece W. As a result, both image quality and productivity can be achieved. Furthermore, since the movement speed of the workpiece W is not increased, even if the workpiece W is supported on the second robotic arm 4 by the gripper mechanism 40, it is possible to prevent the workpiece W from detaching from the second robotic arm 4 or from shifting its position. Additionally, since the head 5a is fixed to the first robotic arm 3 by screws or the like, there is no problem even if the movement speed of the head 5a is increased. Therefore, even if the head movement distance DH is long, the transfer from the first printing step S40 or the second printing step S70 to the maintenance step S82 can be carried out quickly by increasing the movement speed of the head 5a.

[0182] Furthermore, as mentioned above, when viewed from above the base 2, the mounting section 9 and the maintenance unit 8 are located on the same side relative to the imaginary line segment LV. That is, when viewed from above the base 2, the mounting section 9 and the maintenance unit 8 are arranged within one of the two regions divided by the imaginary line segment LV. Therefore, compared to a structure where the mounting section 9 and the maintenance unit 8 are located on opposite sides relative to the imaginary line segment LV when viewed from above the base 2, it is easier to miniaturize the overall device.

[0183] Furthermore, as described above, the stereolithography printing apparatus 1 performs a holding step S11 in which the gripper mechanism 40 receives the workpiece W from the mounting section 9. Here, when viewed from above the base 2, the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 is closer to the imaginary line segment LV than the position of the workpiece W during the holding step S11. The closer the position of the workpiece W is to the imaginary line segment LV, the higher the degree of freedom of movement of the first robotic arm 3 and the second robotic arm 4 during the execution of the first printing step S40 or the second printing step S70. Therefore, by making the position of the workpiece W during the execution of the first printing step S40 or the second printing step S70 closer to the imaginary line segment LV than the position during the holding step S11, the degree of freedom of posture of the workpiece W and the head 5a in the first printing step S40 or the second printing step S70 can be improved. Additionally, as described above, the holding step S11 is included in the material feeding step S10.

[0184] Furthermore, as mentioned above, in the stereolithography printing apparatus 1, when viewed from above the base 2, each of the hardening unit 10 and the maintenance unit 8 is located between a first straight line LS1 that passes through the base 310 of the first robotic arm 3 and is orthogonal to the imaginary line segment LV, and a second straight line LS2 that passes through the base 410 of the second robotic arm 4 and is orthogonal to the imaginary line segment LV. Therefore, it is possible to achieve miniaturization of the stereolithography printing apparatus 1 as a whole.

[0185] 2. Second Implementation Method

[0186] The second embodiment of the present invention will now be described. In the embodiments illustrated below, the symbols used in the description of the first embodiment are retained for elements that have the same function or effect as those in the first embodiment, and detailed descriptions of each are omitted as appropriate.

[0187] Figure 14 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to the second embodiment. This embodiment is the same as the first embodiment described above, except that the execution order of the first curing step S81a, the second curing step S81b, and the maintenance step S82 is different.

[0188] In this embodiment, a post-processing step S80A, including a first hardening step S81a and a maintenance step S82, is performed between the first printing step S40 and the avoidance step S50. Furthermore, a post-processing step S80B, including a second hardening step S81b and a maintenance step S82, is performed between the second printing step S70 and the material removal step S90. Alternatively, a portion of the avoidance step S50 may serve as the post-processing step S80A, or the avoidance step S50 may be omitted.

[0189] Through the second embodiment described above, similar to the first embodiment described above, printing can be appropriately performed on the workpiece W even if it has various three-dimensional shapes. In this embodiment, the three-dimensional printing apparatus 1 sequentially executes the first printing step S40, the first curing step S81a, the second printing step S70, and the second curing step S81b. Therefore, the first printing step S40 and the first curing step S81a can be performed continuously. As a result, since the ink sprayed onto the workpiece W in the first printing step S40 can be cured immediately in the first curing step S81a, image bleeding caused by ink flow on the workpiece W can be reduced. Similarly, the second printing step S70 and the second curing step S81b can be performed continuously. As a result, since the ink sprayed onto the workpiece W in the second printing step S70 can be cured immediately in the second curing step S81b, image bleeding caused by ink flow on the workpiece W can be reduced.

[0190] 3. Variations

[0191] The methods illustrated above can be modified in a variety of ways. Specific modifications applicable to the methods described above are illustrated below. Furthermore, two or more methods arbitrarily selected from the following examples can be appropriately combined without contradiction.

[0192] 3-1. Variation Example 1

[0193] Figure 15 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to Modification Example 1. Modification Example 1 is the same as the first embodiment described above, except that the adjustment step S30 is omitted and the first printing step S40A and the second printing step S70A are performed instead of the first printing step S40 and the second printing step S70A.

[0194] In each of the first printing step S40 and the second printing step S70, the path by which the head 5a is moved by the first robotic arm 3 is adjusted based on the information obtained in the information acquisition step S20. Therefore, even if the support position of the workpiece W implemented by the second robotic arm 4 deviates from the desired position, this adjustment can reduce errors in the relative position and orientation of the head 5a and the workpiece W. Similarly to the first embodiment described above, through the above variation 1, the workpiece W can be appropriately printed even if it has various three-dimensional shapes.

[0195] 3-2. Variation Example 2

[0196] Figure 16 This is a top view of the stereolithography printing apparatus 1A according to Modification Example 2. Except for the number of three imaging units 7, the stereolithography printing apparatus 1A has the same structure as the stereolithography printing apparatus 1 of the first embodiment described above. Specifically, in addition to having an imaging unit 7 for imaging in the Y1 direction, as in the first embodiment, the stereolithography printing apparatus 1A also has an imaging unit 7 for imaging in the Z1 direction and an imaging unit 7 for imaging in the X1 direction.

[0197] Through the above-described Modification 2, similar to the first embodiment described above, printing can be appropriately performed on the workpiece W even if it has various three-dimensional shapes. In Modification 2, since the number of imaging units 7 is greater than that in the first embodiment, it has the advantage of easily improving the detection accuracy of the position and orientation of the workpiece W obtained from the imaging results of the imaging units 7. Here, it is preferable that the workpiece W during printing is located inside the area where the imaging ranges of the imaging devices 7a of these imaging units 7 overlap.

[0198] 3-3. Variation Example 3

[0199] Although the structure of a six-axis vertical multi-axis robotic arm was exemplified as a moving mechanism in the foregoing description, it is not limited to this structure. The moving mechanism only needs to be able to change the relative position and orientation of the liquid nozzle in three dimensions relative to the workpiece. Therefore, the moving mechanism can be, for example, a vertical multi-axis robotic arm other than six axes, or a horizontal multi-axis robotic arm. Furthermore, the robotic arm may have a telescopic mechanism in addition to the joints formed by the rotating mechanism. However, from the viewpoint of balancing the print quality during printing operations with the degrees of freedom of the moving mechanism during non-printing operations, a multi-axis robotic arm with six or more axes is preferred. In addition, a dual-arm robotic arm can be used, in which case one arm can be used as the first robotic arm and the other arm as the second robotic arm.

[0200] 3-4. Variation Example 4

[0201] Although the structure described above illustrates a method of fixing the head relative to the first robotic arm using screws or similar fastening mechanisms, it is not limited to this structure. For example, the head can also be fixed relative to the first robotic arm by gripping it with a gripping mechanism such as a gripper mounted on the end effector of the first robotic arm.

[0202] 3-5. Variation Example 5

[0203] Although the foregoing description illustrates a structure that uses one type of ink for printing, it is not limited to that structure and can also be applied to structures that use two or more types of ink for printing.

[0204] 3-6. Variation Example 6

[0205] The application of the three-dimensional printing apparatus of the present invention is not limited to printing. For example, the three-dimensional printing apparatus that sprays a solution of color material can be used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Furthermore, the three-dimensional printing apparatus that sprays a solution of conductive material can be used as a manufacturing apparatus for forming wiring or electrodes for wiring substrates. In addition, the three-dimensional printing apparatus can also be used as a spray dispenser for applying liquids such as adhesives to workpieces.

[0206] Symbol Explanation

[0207] 1…Stereolithography printing apparatus; 1A…Stereolithography printing apparatus; 2…Base; 2a…Surface; 2b…Exhaust port; 3…First robotic arm; 3a…Arm drive mechanism; 4…Second robotic arm; 4a…Arm drive mechanism; 5…Liquid ejection unit; 5a…Head; 5b…Pressure regulating valve; 5c…Pre-curing light source; 5d…Switching circuit; 5e…Support body; 6…Ink supply unit; 6a…Ink tank; 6b…Supply pipe; 6c…Sub-tank; 6d…Supply pipe; 7…Illumination unit; 7a…Illumination device; 7b…Lighting unit; 8…Maintenance unit; 8a…Unit; 8b…Unit; 9…Placement; 9a…Surface; 10…Curing unit; 10a…Light shielding component; 10b…Light source; 11…Controller ; 11a…Storage circuit; 11b…Processing circuit; 12…Control module; 12a…Timing signal generation circuit; 12b…Power supply circuit; 12c…Control circuit; 12d…Drive signal generation circuit; 13…Computer; 20…Housing; 40…Grappling mechanism; 310…Base; 320…Arm; 321…Arm; 322…Arm; 323…Arm; 324…Arm; 325…Arm; 326…Arm; 330_1…Joint; 330_2…Joint; 330_3…Joint; 330_4…Joint; 330_5…Joint; 330_6…Joint; 410…Base; 420…Arm; CLK…Clock signal; CNG…Switching signal; Com…Driver Signal; D1…output; D2…output; D3…signal; DH…head movement distance; DW…workpiece movement distance; Da…path information; Db…path information; F…nozzle face; LAT…latch signal; LS1…first straight line; LS2…second straight line; LV…imaginary line segment; La…first nozzle array; Lb…second nozzle array; N…nozzle; O1…rotation axis; O2…rotation axis; O3…rotation axis; O4…rotation axis; O5…rotation axis; O6…rotation axis; PD…drive pulse; PTS…timing signal; RI…shooting range; RL…illumination range; RP1…first area; RP2…second area; RR1…action range; RR2…action range; S10…feeding step S11…Holding step; S20…Information acquisition step; S30…Adjustment step; S40…First printing step; S40A…First printing step; S50…Avoidance step; S60…Movement step; S70…Second printing step; S70A…Second printing step; S80…Post-processing step; S80A…Post-processing step; S80B…Post-processing step; S81…Hardening step; S81a…First hardening step; S81b…Second hardening step; S82…Maintenance step; S90…Material removal step; SI…Control signal; Sk1…Control signal; Sk2…Control signal; VBS…Offset potential; VHV…Power supply potential; W…Workpiece; dCom…Waveform specification signal.

Claims

1. A three-dimensional printing apparatus, characterized in that, have: The first robotic arm supports a head with a nozzle that sprays liquid and changes the position and orientation of the head. The second robotic arm supports the three-dimensional workpiece and changes its position and orientation. The length of the first robotic arm is shorter compared to the length of the second robotic arm. The first printing step is performed, in which the first robotic arm scans the head along a first region of the workpiece while the head sprays liquid onto the first region. In the first printing step, the second robotic arm fixes the position and orientation of the workpiece in a first state. The moving step is performed after the first printing step. During the movement step, the second robotic arm changes the position and orientation of the workpiece from the first state to a second state that differs from the first state. An avoidance step is performed between the first printing step and the moving step. In the avoidance step, the first robotic arm increases the distance between the head and the workpiece compared to when the first printing step is performed.

2. A three-dimensional printing apparatus, characterized in that, have: The first robotic arm supports a head with a nozzle that sprays liquid and changes the position and orientation of the head. The second robotic arm supports the three-dimensional workpiece and changes its position and orientation. The first robotic arm has a larger payload capacity compared to the second robotic arm. The first printing step is performed, in which the first robotic arm scans the head along a first region of the workpiece while the head sprays liquid onto the first region. In the first printing step, the second robotic arm fixes the position and orientation of the workpiece in a first state. The moving step is performed after the first printing step. During the movement step, the second robotic arm changes the position and orientation of the workpiece from the first state to a second state that differs from the first state. An avoidance step is performed between the first printing step and the moving step. In the avoidance step, the first robotic arm increases the distance between the head and the workpiece compared to when the first printing step is performed.

3. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, It also includes a hardening unit, which is fixed to the base and emits energy that causes the liquid from the head to harden or solidify. After the first printing step is performed, a first hardening step is performed. In the first hardening step, while the second robotic arm changes the relative position and orientation of the hardening unit and the workpiece, the hardening unit irradiates energy onto the liquid in the first area.

4. The three-dimensional printing apparatus as described in claim 3, characterized in that, It also includes a maintenance unit that performs maintenance on the head. A maintenance step is performed during the execution of the first hardening step, in which maintenance of the head is carried out by the maintenance unit.

5. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, Following the movement step, a second printing step is performed, in which, while the first robotic arm scans the workpiece along a second region different from the first region, the head sprays liquid onto the second region. In the second printing step, the second robotic arm fixes the position and posture of the workpiece to the second state.

6. The three-dimensional printing apparatus as described in claim 5, characterized in that, The actions of the first robotic arm in the first printing step are the same as those of the first robotic arm in the second printing step.

7. The three-dimensional printing apparatus as described in claim 3, characterized in that, Following the movement step, a second printing step is performed, in which, while the first robotic arm scans the workpiece along a second region different from the first region, the head sprays liquid onto the second region. In the second printing step, the second robotic arm fixes the position and orientation of the workpiece in the second state. After the second printing step is performed, a second hardening step is performed. In the second hardening step, while the second robotic arm changes the relative position and orientation of the hardening unit and the workpiece, the hardening unit irradiates energy onto the liquid in the second region.

8. The three-dimensional printing apparatus as described in claim 7, characterized in that, It also includes a maintenance unit that performs maintenance on the head. During the execution of the second hardening step, a maintenance step is performed, in which maintenance of the head is carried out by the maintenance unit.

9. The three-dimensional printing apparatus as described in claim 7, characterized in that, The first printing step, the second printing step, the first hardening step, and the second hardening step are executed sequentially.

10. The three-dimensional printing apparatus as claimed in claim 7, characterized in that, The first printing step, the first hardening step, the second printing step, and the second hardening step are executed sequentially.

11. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, The second robotic arm has a gripper mechanism that holds the workpiece in a load-and-unloadable manner.

12. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, Each of the first robotic arm and the second robotic arm is a vertical multi-joint robotic arm.

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