3D printing apparatus and 3D printing method

Abstract

This invention relates to a three-dimensional printing apparatus and a three-dimensional printing method. The three-dimensional printing apparatus includes: a head having a nozzle surface with a nozzle array; and a robotic arm having a base and an arm, with a plurality of rotating parts extending from the base to the arm. The position of the head relative to the base is changed by rotating the rotating parts. The three-dimensional printing apparatus performs a first printing action and a second printing action. The first printing action is an action of printing an image by spraying liquid onto the first medium while the position of the head relative to a three-dimensional first medium is changed by the robotic arm, and the second printing action is an action of printing a test pattern by spraying liquid onto the second medium while the position of the head relative to a second medium is changed by the robotic arm to a position different from the position during the execution of the first printing action. The yaw angle of the head during the execution of the first printing action is different from the yaw angle of the head during the execution of the second printing action.

Description

Technical Field

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

[0002] A three-dimensional printing apparatus is known for printing on the surface of a three-dimensional workpiece by inkjet printing. For example, the apparatus described in Patent Document 1 has a robotic arm and a print head fixed to the top of the robotic arm, and prints an image formed by ink from the print head onto the object.

[0003] The apparatus described in Patent Document 1 has the following problem: when a blockage or other malfunction occurs in the nozzle of the print head, printing with reduced image quality is performed on the object.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-050832 Summary of the Invention

[0005] To address the above-mentioned issues, one aspect of the stereolithography printing apparatus of the present invention comprises: a head having a nozzle surface on which a nozzle array for ejecting liquid is arranged; a robotic arm having a base and an arm supporting the head, and having a plurality of rotating parts extending from the base to the arm, wherein the position of the head relative to the base is changed by rotation of the rotating parts; the stereolithography printing apparatus performs a first printing action and a second printing action, wherein the first printing action is an action of ejecting liquid onto the first medium by the head to print an image while the robotic arm changes the position of the head relative to a stereolithographic first medium; the second printing action is an action of ejecting liquid onto the second medium by the head to print a test pattern while the robotic arm changes the position of the head relative to a second medium to a position different from the position during the execution of the first printing action; wherein the yaw angle of the head during the execution of the first printing action and the yaw angle of the head during the execution of the second printing action are different from each other.

[0006] One aspect of the three-dimensional printing method of the present invention uses the following components: a head having a nozzle surface on which a nozzle array for ejecting liquid is arranged; a robotic arm having a base and an arm supporting the head, and having a plurality of rotating parts extending from the base to the arm, wherein the position of the head relative to the base is changed by rotating the rotating parts. In the three-dimensional printing method, a first printing action and a second printing action are performed. The first printing action is an action of printing an image by ejecting liquid from the head onto the first medium while the robotic arm changes the position of the head relative to the first three-dimensional medium. The second printing action is an action of printing a test pattern by ejecting liquid from the head onto the second medium while the robotic arm changes the position of the head relative to the second medium to a position different from the position during the execution of the first printing action. The yaw angle of the head during the execution of the first printing action is different from the yaw angle of the head during the execution of the second printing action. Attached Figure Description

[0007] Figure 1 A perspective view showing the outline of the three-dimensional printing apparatus according to the embodiment.

[0008] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus according to the embodiment.

[0009] Figure 3 A three-dimensional diagram showing the outline structure of the head unit.

[0010] Figure 4 A three-dimensional view showing the outline structure of the maintenance unit.

[0011] Figure 5 A flowchart illustrating the operation of the three-dimensional printing apparatus according to the embodiment.

[0012] Figure 6 This is a side view of the robotic arm during the execution of the first printing action.

[0013] Figure 7 This is a top view of the three-dimensional printing apparatus during the execution of the first printing action.

[0014] Figure 8 A top view of the three-dimensional printing device during the maintenance operation. Detailed Implementation

[0015] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions and scales of the various parts in the drawings differ appropriately from actual dimensions, and some parts are shown schematically for ease of understanding. Furthermore, unless otherwise specified in the following description, the scope of the present invention is not limited to these embodiments.

[0016] For ease of explanation, the following description appropriately uses intersecting X-axis, Y-axis, and Z-axis. Furthermore, in the following description, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 and Y2 directions. Additionally, the opposite directions along the Z-axis are the Z1 and Z2 directions.

[0017] Here, the X, Y, and Z axes correspond to the coordinate axes of a universal coordinate system established within the space in which the robotic arm 2, described later, is located. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. A reference coordinate system based on the position of the base 210 of the robotic arm 2, described later, is established to correspond with this universal coordinate system through calibration. In the following text, for ease of explanation, an example is given of using the universal coordinate system as the robotic arm coordinate system to control the movement of the robotic arm 2.

[0018] 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°.

[0019] 1. First Implementation Method

[0020] 1-1. Overview of a 3D printing apparatus

[0021] Figure 1 This is a perspective view showing an outline of the three-dimensional printing apparatus 1 according to the embodiment. The three-dimensional printing apparatus 1 is an apparatus that performs printing on the surface of a three-dimensional first medium W1 by inkjet printing.

[0022] The first medium W1 has a surface WF1 that becomes the object of printing. Figure 1 In the example shown, the first medium W1 is an ellipsoidal rugby ball, and its surface WF1 is curved. During printing, the first medium W1 is supported as needed, for example by a predetermined mounting platform, robotic gripper, or conveyor belt. Furthermore, the shape or size of the first medium W1 or its surface WF1 is not limited to... Figure 1The example shown is not an example of any particular method. Furthermore, the position or orientation of the first medium W1 or surface WF1 during printing is not limited to any particular configuration, as long as printing is possible. Figure 1 The example shown is not for any position or orientation.

[0023] like Figure 1 As shown, the three-dimensional printing apparatus 1 includes a robotic arm 2, a head unit 3, a maintenance unit 4, a controller 5, a piping unit 10, and a wiring unit 11. These components will be briefly described in turn below.

[0024] Robotic arm 2 is the robotic arm that changes the position and orientation of head unit 3 in the general coordinate system. Figure 1 In the example shown, robotic arm 2 is a so-called six-axis vertical multi-joint robotic arm.

[0025] like Figure 1 As shown, the robotic arm 2 has a base 210 and an arm 220.

[0026] The base 210 is a platform that supports the arm 220. Figure 1 In the example shown, the base 210 is fixed to a mounting surface such as a floor surface or base facing the Z1 direction by means of screws or the like. Furthermore, the mounting surface to which the base 210 is fixed can be a surface facing any direction, and is not limited to any particular direction. Figure 1 The example shown can also be a surface such as a wall, ceiling, or movable flatbed vehicle. Furthermore, in the following text, the case of viewing in a direction perpendicular to the mounting surface of the base 210, that is, viewing in the Z1 or Z2 direction in this embodiment, is sometimes referred to as "top view of the base 210", or simply "top view".

[0027] Arm 220 is a six-axis robotic arm having a base end mounted on base 210 and a tip that allows its position and orientation to change three-dimensionally relative to the base end. Specifically, arm 220 has arms 221, 222, 223, 224, 225, and 226, which are connected in this order.

[0028] Arm 221 is connected to base 210 via joint 230_1, allowing it to rotate about rotation axis O1. Arm 222 is connected to arm 221 via joint 230_2, allowing it to rotate about rotation axis O2. Arm 223 is connected to arm 222 via joint 230_3, allowing it to rotate about rotation axis O3. Arm 224 is connected to arm 223 via joint 230_4, allowing it to rotate about rotation axis O4. Arm 225 is connected to arm 224 via joint 230_5, allowing it to rotate about rotation axis O5. Arm 226 is connected to arm 225 via joint 230_6, allowing it to rotate about rotation axis O6.

[0029] Each of joints 230_1 to 230_6 is an example of a "rotating part," and is a mechanism that rotatably connects one of two adjacent components, the base 210 and the arms 221 to 226, to the other. Here, joint 230_1, the joint closest to the base 210 among joints 230_1 to 230_6, is an example of a "first rotating part." Furthermore, joint 230_6, the joint furthest from the base 210 among joints 230_1 to 230_6, is an example of a "second rotating part." Additionally, in the following text, each of joints 230_1 to 230_6 will sometimes be referred to as "joint 230."

[0030] Although Figure 1 Although not illustrated, each of the joints 230_1 to 230_6 is provided with a drive mechanism that causes one of the corresponding two adjacent components to rotate 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 these drive mechanisms for joints 230_1 to 230_6 corresponds to the description below. Figure 2 The arm drive mechanism 2a shown is illustrated.

[0031] Rotation axis O1 is a perpendicular axis to a mounting surface (not shown) on which the base 210 is fixed. Rotation axis O2 is a perpendicular axis to rotation axis O1. Rotation axis O3 is a parallel axis to rotation axis O2. Rotation axis O4 is a perpendicular axis to rotation axis O3. Rotation axis O5 is a perpendicular axis to rotation axis O4. Rotation axis O6 is a perpendicular axis to rotation axis O5.

[0032] 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°.

[0033] On the uppermost arm 226 of the arm portion 220 of the robotic arm 2 described above, a head unit 3 is mounted as an end effector and is fixed in a fixed state by means of screws or the like.

[0034] Head unit 3 is an assembly having a head 3a that ejects ink, an example of a "liquid," toward the first medium W1. In this embodiment, in addition to the head 3a, head unit 3 also includes a pressure regulating valve 3b, a curing light source 3c, a distance sensor 3d, and a camera device 3g. Further details regarding head unit 3 will be provided later. Figure 3 Let me explain.

[0035] 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 the first medium W1.

[0036] A piping section 10 and a wiring section 11 are connected to the head unit 3. The piping section 10 includes piping or a piping assembly including a supply pipe 10a that supplies ink from an ink tank (not shown) to the head unit 3. The supply pipe 10a is, for example, a flexible tube made of a rubber or elastomer material. The wiring section 11 includes wiring or a wiring assembly including a drive wiring 11a that supplies electrical signals to drive the head unit 3a. The drive wiring 11a is, for example, made of various flexible electronic wiring. In addition to the supply pipe 10, the piping section 10 may also include other piping, such as piping for transporting ink discharged from the head unit 3. Furthermore, in addition to the drive wiring 11a, the wiring section 11 may appropriately include various wiring for transmitting other electronic signals, such as the control signal SI (described later), necessary for the operation of the head unit 3.

[0037] Each of the piping section 10 and wiring section 11 is fixed in a position relative to the head unit 3 through connection with the head unit 3. Fixed position FX1 is a position within the end effector, specifically, the position of a connector (not shown) for connecting the piping section 10 and wiring section 11 to the head unit 3. Furthermore, each of the piping section 10 and wiring section 11 is fixed relative to the arm 220 of the aforementioned robotic arm 2 at fixed positions FX2, FX3, and FX4 by cable ties or the like. Fixed position FX2 is the position on the arm 224 described above. Fixed position FX3 is the position on the arm 223 described above. Fixed position FX4 is the position on the arm 222 described above. Thus, by partially fixing the piping section 10 and wiring section 11 to multiple positions on the arm 220, it is possible to maintain the positional relationship between the arm 220 and the piping section 10 and wiring section 11 within a predetermined range while sufficiently allowing the arm 220 to move. Additionally, although in Figure 1 The example illustrates a structure in which the winding paths of the piping section 10 and the wiring section 11 are the same, but it is also possible for the winding paths of the piping section 10 and the wiring section 11 to be different.

[0038] Maintenance unit 4 is a mechanism for performing maintenance on the head 3a of head unit 3. Figure 1In the example shown, maintenance unit 4 includes a housing 4a, a cover 4b, a support 4c, a suction mechanism 4d, a wiping unit 4e, and an inspection unit 4f. The housing 4a supports the cover 4b, the support 4c, the suction mechanism 4d, and the wiping unit 4e. The cover 4b covers the nozzle surface F of head 3a, which will be described later. The support 4c applies force to the cover 4b towards the nozzle surface F of head 3a, which will be described later. The suction mechanism 4d depressurizes the space formed between the cover 4b and the nozzle surface F of head 3a, which will be described later. The wiping unit 4e wipes the nozzle surface F of head 3a, which will be described later. The inspection unit 4f supports a second medium W2, such as paper or film, having a surface WF2 for printing a test pattern used to check the ink ejection function of head 3a. Further details regarding maintenance unit 4 will be provided later. Figure 3 Let me explain.

[0039] Controller 5 is a robotic arm controller that controls the drive of robotic arm 2. The following is based on... Figure 2 The electrical structure of the stereolithography printing apparatus 1 is described in such a manner that a detailed description of the controller 5 is included.

[0040] 1-2. Electrical Structure of the Three-Dimensional Printing Apparatus

[0041] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 1 according to the embodiment. Figure 2 The diagram shows the electrical structural elements within the structural elements of the three-dimensional printing apparatus 1. For example... Figure 2 As shown, the stereolithography printing apparatus 1, in addition to having the features described above... Figure 1 In addition to the structural elements shown, the system also includes a control module 6 that is communicatively connected to the controller 5, and a computer 7 that is communicatively connected to both the controller 5 and the control module 6. Before providing a detailed description of the controller 5, the control module 6 and the computer 7 will be described in turn.

[0042] in addition, Figure 2 The electrical structural elements shown can be appropriately divided, partially incorporated into other structural elements, or integrally formed with other structural elements. For example, some or all of the functions of controller 5 or control module 6 can be implemented by computer 7, or by other external devices such as PCs connected to controller 5 via networks such as LAN (Local Area Network) or the Internet.

[0043] The controller 5 has the function of controlling the drive of the robotic arm 2 and generating a signal D3 to synchronize the ink ejection action in the head unit 3 with the action of the robotic arm 2. Additionally, although the controller 5 in this embodiment also has the function of controlling the drive of the maintenance unit 4, this function can also be implemented by other devices such as the computer 7.

[0044] The controller 5 has a storage circuit 5a and a processing circuit 5b.

[0045] The storage circuit 5a stores various programs executed by the processing circuit 5b and various data processed by the processing circuit 5b. The storage circuit 5a 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 5a may also be included in the processing circuit 5b.

[0046] The storage circuit 5a stores path information Da. Path information Da represents the path that the head unit 3 should move along and the orientation of the head unit 3 along that path. Here, path information Da, as information representing the path and orientation, includes information representing the movement path and orientation of the head unit 3 when printing on the first medium W1, and information representing the movement path and orientation between the position of the head unit 3 during printing and the position during maintenance performed by the maintenance unit 4. Path information Da is determined, for example, based on the shape of the first medium W1, and is represented using coordinate values ​​from a reference coordinate system or a universal coordinate system. The shape of the first medium W1 is obtained, for example, from CAD (computer-aided design) data representing the three-dimensional shape of the first medium W1. The path information Da described above is input from the computer 7 to the storage circuit 5a.

[0047] The processing circuit 5b controls the movement of the arm drive mechanism 2a of the robotic arm 2 based on the path information Da, and generates a signal D3. The processing circuit 5b may include, for example, one or more processors such as a CPU (Central Processing Unit). Alternatively, the processing circuit 5b may replace the CPU or include programmable logic devices such as an FPGA (Field-Programmable Gate Array) in addition to a CPU.

[0048] Here, the arm drive mechanism 2a is an assembly of the drive mechanisms of the joints 230_1 to 230_6 described above, and for each joint, it has a motor for driving the joint of the robotic arm 2 and an encoder for detecting the rotation angle of the joint of the robotic arm 2.

[0049] Processing circuit 5b performs inverse kinematics calculations, converting path information Da into motion quantities such as rotation angles and rotational speeds of each joint of the robotic arm 2. Furthermore, processing circuit 5b outputs control signals Sk1 based on the outputs D1 from each encoder of the arm drive mechanism 2a, so that the actual rotation angles and rotational speeds of each joint become the calculation results described above based on the path information Da. Control signals Sk1 control the drive of the motors in the arm drive mechanism 2a. Here, control signals Sk1 are corrected by processing circuit 5b as needed and based on the output from distance sensor 3d.

[0050] Furthermore, the processing circuit 5b generates a signal D3 based on the output D1 of at least one of the plurality of encoders from the arm drive mechanism 2a. For example, the processing circuit 5b generates a trigger signal as signal D3, the trigger signal containing a timing pulse from the output D1 of one of the plurality of encoders when it reaches a predetermined value.

[0051] The control module 6 is a circuit that controls the ink ejection action in the head unit 3 based on the signal D3 output from the controller 5 and the printing data from the computer 7. The control module 6 includes a timing signal generation circuit 6a, a power supply circuit 6b, a control circuit 6c, and a drive signal generation circuit 6d.

[0052] The timing signal generation circuit 6a generates a timing signal PTS based on signal D3. The timing signal generation circuit 6a is, for example, composed of a timer that starts generating the timing signal PTS upon detection of signal D3.

[0053] The power supply circuit 6b receives power from a commercial power supply not shown in the diagram and generates various predetermined potentials. These potentials are appropriately supplied to the control module 6 and various parts of the head unit 3. For example, the power supply circuit 6b generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the head unit 3. Furthermore, the power supply potential VHV is supplied to the drive signal generation circuit 6d.

[0054] The control circuit 6c 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 6d, while the other signals are input to the switching circuit 3e of the head unit 3.

[0055] The control signal SI is a digital signal used to specify the operating state of the drive element of the head 3a of the head unit 3. Specifically, the control signal SI specifies whether to supply the drive signal Com (described later) to the drive element. By specifying this, for example, whether ink is ejected from the nozzle corresponding to the drive element, or the amount of ink ejected from the nozzle, is specified. 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 specify the timing of ink ejection from the nozzle by specifying the drive timing of the drive element in conjunction with the control signal SI. The clock signal CLK is a clock signal that serves as a reference synchronized with the timing signal PTS.

[0056] The control circuit 6c described above includes, for example, one or more processors such as CPUs (Central Processing Units). Alternatively, the control circuit 6c can replace a CPU or include programmable logic devices such as FPGAs (field-programmable gate arrays) in addition to a CPU.

[0057] The drive signal generation circuit 6d is a circuit that generates drive signals Com for driving the drive elements of the head 3a of the head unit 3. Specifically, the drive signal generation circuit 6d includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 6d, the waveform specification signal dCom from the control circuit 6c is converted from a digital signal to an analog signal by the DA conversion circuit, and the analog signal is amplified by the amplification circuit using the power supply potential VHV from the power supply circuit 6b, thereby generating the drive signal Com. Here, the 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 6d via the switching circuit 3e of the head unit 3.

[0058] Here, the switching circuit 3e is a circuit that switches whether to supply at least a portion of the waveform contained in the drive signal Com as a drive pulse PD based on the control signal SI.

[0059] The computer 7 has the function of supplying path information Da and other information to the controller 5, and the function of supplying printing data and other information to the control module 6. In addition to these functions, the computer 7 of this embodiment also has the function of controlling the driving of the curing light source 3c, and the function of analyzing the printing results of the test pattern based on the imaging results of the imaging device 3g and displaying the analysis results on a display device (not shown) or inputting them into the controller 5. The computer 7 is, for example, a desktop or laptop computer with programs that implement these functions installed.

[0060] 1-3. Structure of the head unit

[0061] Figure 3 This is a perspective view showing the general structure of head unit 3. In the following description, intersecting a-axis, b-axis, and c-axis are used appropriately for ease of explanation. Furthermore, in the following description, one direction along the a-axis is the a1 direction, and the direction opposite to the a1 direction is the a2 direction. Similarly, the opposite directions along the b-axis are the b1 direction and the b2 direction. Furthermore, the opposite directions along the c-axis are the c1 direction and the c2 direction.

[0062] Here, the a-axis, b-axis, and c-axis correspond to the coordinate axes of the tool coordinate system set in the head unit 3, and their relative positions and orientations with the general coordinate system or robotic arm coordinate system described above change due to the movements of the robotic arm 2 described above. Figure 3 In the example shown, the c-axis is parallel to the 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 only need to intersect at angles within the range of 80° to 100°. Additionally, the tool coordinate system is established to correspond with the reference coordinate system or the robot arm coordinate system 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).

[0063] As mentioned above, head unit 3 includes a head 3a, a pressure regulating valve 3b, a hardening light source 3c, a distance sensor 3d, and a camera device 3g. These are... Figure 3 It is supported by the support body 3f, indicated by the double-dotted line. Additionally, although in Figure 3 In the example shown, the head unit 3 has one head 3a and one pressure regulating valve 3b, but this number is not limited to one. Figure 3 The example shown can also include more than two. Furthermore, the position of the pressure regulating valve 3b is not limited to arm 226; for example, it can be other arms or a position fixed relative to the base 210.

[0064] The support 3f is constructed of, for example, a metallic material and is essentially a rigid body. Furthermore, although in Figure 3 The middle support 3f is a flat box shape, but the shape of the support 3f is not particularly limited, but can be any shape.

[0065] The aforementioned support body 3f is mounted on the arm 226 described above. Therefore, the head 3a, pressure regulating valve 3b, hardening light source 3c, distance sensor 3d, and camera device 3g are all supported together on the arm 226 by the support body 3f. Thus, the relative positions of the head 3a, pressure regulating valve 3b, hardening light source 3c, distance sensor 3d, and camera device 3g relative to the arm 226 are fixed. Figure 3 In the example shown, a pressure regulating valve 3b is positioned at a c1 direction relative to the head 3a. A hardening light source 3c is positioned at a a2 direction relative to the head 3a. A distance sensor 3d is positioned at a1 direction relative to the head 3a. An imaging device 3g is positioned at a b1 direction relative to the head 3a.

[0066] The head 3a has a nozzle face F and multiple nozzles N that open on the nozzle face F. Figure 3 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 nozzle rows La and Lb arranged at intervals along the a-axis. Each of nozzle rows La and 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 nozzle row La and each nozzle N in nozzle row Lb in the first 3a are structurally approximately symmetrical with each other along the a-axis. Furthermore, the arrangement direction DN, described later, is parallel to the b-axis.

[0067] Furthermore, in this embodiment, the nozzle surface F refers to a concept that includes both the surface formed by the nozzle plate and the surface formed by the fixing plate and the head cover. The nozzle plate is a plate-shaped component with nozzles N opened on it, made of materials such as silicon (Si) or metal. The fixing plate and head cover are components provided around the nozzle plate for purposes such as fixing and protecting it. Sometimes, the fixing plate and head cover are not provided depending on the head structure. Figure 3 The nozzle surface F shown is formed solely by the nozzle plate.

[0068] However, the positions of the multiple nozzles N in nozzle array La and the multiple nozzles N in nozzle array Lb along the b-axis can be either consistent or different. Furthermore, elements associated with each nozzle N in either nozzle array La or nozzle array Lb can be omitted. The following example illustrates a structure where the positions of the multiple nozzles N in nozzle array La and the multiple nozzles N in nozzle array Lb are consistent along the b-axis.

[0069] Although not shown in the figure, the head 3a has a piezoelectric element as a driving element and a cavity for collecting ink for each nozzle N. Here, the piezoelectric element causes a change in pressure in the cavity corresponding to the piezoelectric element, thereby causing ink to be ejected from the nozzle corresponding to the cavity. Such a head 3a is obtained by bonding together multiple substrates, such as silicon substrates, which have been appropriately processed by etching or the like, using adhesives or the like. Alternatively, a heater that heats the ink in the cavity can be used instead of the piezoelectric element as a driving element for ejecting ink from the nozzle.

[0070] As mentioned above, in the head 3a, ink is supplied to the ink tank (not shown) via the supply pipe 10a. Here, a pressure regulating valve 3b is provided between the supply pipe 10a and the head 3a.

[0071] The pressure regulating valve 3b is a valve mechanism that opens and closes according to the pressure of the ink in the head 3a. By opening and closing this valve, even if the positional relationship between the head 3a and the ink reservoir (not shown) described above changes, the pressure of the ink in the head 3a is maintained at a negative pressure within a predetermined range. Therefore, the meniscus of the ink formed in the nozzle N of the head 3a 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 3b is appropriately distributed to multiple parts of the head 3a via a branch channel (not shown). Here, the ink from the ink reservoir (not shown) is transported to the supply pipe 10a at a predetermined pressure by a pump or the like.

[0072] The curing light source 3c emits energy such as light, heat, electron beams, or radiation to cure or harden the ink on the first medium W1. For example, if the ink has ultraviolet curing properties, the curing light source 3c is composed of a light-emitting element such as an LED (light emitting diode) that emits ultraviolet light. Furthermore, the curing light source 3c may also appropriately include optical components such as lenses for adjusting the direction or range of energy emission.

[0073] Alternatively, the curing light source 3c may not completely harden or cure the ink on the first medium W1. In this case, for example, the ink irradiated by the energy from the curing light source 3c may be completely hardened or cured simply by the energy from the curing light source located on the mounting surface of the base 210 of the robotic arm 2. Furthermore, the curing light source 3c may be omitted as needed.

[0074] The distance sensor 3d is an optical displacement sensor that measures the distance between the head 3a and the first medium W1. In this embodiment, the distance sensor 3d outputs a signal corresponding to the distance between the head 3a and the first medium W1 along the c-axis. Furthermore, the distance sensor 3d can be omitted as needed.

[0075] The imaging device 3g is a camera used to capture images of a test pattern printed on a second medium W2. The imaging device 3g includes an imaging optical system and an imaging element. The imaging optical system is an optical system including at least one imaging lens, which may include various optical elements such as prisms, or 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. The imaging device 3g has a rectangular pixel area composed of multiple pixels of the imaging element, and is configured such that the long side of the pixel area is parallel to the arrangement direction DN of the multiple nozzles N described above. Furthermore, the imaging device 3g is equipped with a dual-axis or tri-axis imaging coordinate system based on the position of any pixel in the pixel area. This imaging coordinate system is established to correspond with the aforementioned reference coordinate system or universal coordinate system through calibration. In addition to the camera optical system and camera elements, the camera device 3g may also include a lighting device for illuminating the camera area, as needed. This lighting device may be, for example, a light source including a light-emitting element such as an LED (light-emitting diode).

[0076] 1-4. Structure of the maintenance unit

[0077] Figure 4 This is a perspective view showing the outline structure of maintenance unit 4. As mentioned above, Figure 4 The maintenance unit 4 shown has a housing 4a, a cover 4b, a support platform 4c, a suction mechanism 4d, a wiping unit 4e, and an inspection unit 4f.

[0078] The housing 4a is a box-shaped structure that supports the cover 4b, the support platform 4c, the suction mechanism 4d, and the wiping unit 4e. Furthermore, the shape of the housing 4a is not limited to... Figure 4 The example shown is not for any shape.

[0079] The cover 4b is a structure comprising a cover 4b1 that covers the nozzle surface F of the head 3a, a guide 4b2, and a force-applying mechanism 4b3. Figure 4 In the example shown, the cover 4b is elongated. The cover 4b1 is an elastic cover made of rubber or an elastomer, which prevents the ink near the nozzle N of the head 3a from drying by covering the nozzle surface F of the head 3a. The cover 4b1 includes an outer frame portion that abuts against the nozzle surface F of the head 3a, a bottom surface recessed in the Z2 direction relative to the outer frame portion, and a hole penetrating the cover 4b1. During the covering action of covering the nozzle surface F of the head 3a with the cover 4b, the outer frame portion abuts against the nozzle surface F of the head 3a in a manner that surrounds the nozzle N set on the horizontally positioned nozzle surface F. Furthermore, the bottom surface faces the nozzle surface F at this time. The hole has an opening at one end on the bottom surface of the recess and an opening at the other end connected to the suction mechanism 4d.

[0080] The force-applying mechanism 4b3 supports the cover 4b1 and applies force in the Z1 direction, and is constructed using an elastic body such as a spring or rubber. The guide part 4b2 is a component that restricts the movement of the cover 4b1 in a direction different from the Z direction. When the nozzle surface F of the head 3a abuts against the outer frame part described above, the elastic body of the force-applying mechanism 4b3 elastically deforms by contracting in the Z direction. Alternatively, the force-applying mechanism 4b3 can also be a mechanism such as a gas strut.

[0081] The cover 4b is supported by a support platform 4c. The support platform 4c is constructed by a top surface 4c1 on which the cover 4b is fixed, and multiple feet 4c2 that support the top surface 4c1. The top surface 4c1 is a plate-shaped component made of metal or the like, and the cover 4b and the wiper part 4e are fixed to the top surface 4c1 by screws or the like. In addition, a groove recessed in the Z2 direction is formed on the top surface 4c1.

[0082] The suction mechanism 4d is a mechanism for depressurizing the space formed between the cover 4b and the nozzle surface F. By utilizing this depressurization, ink is drawn from the nozzle N of the head 3a when the nozzle surface F is covered by the cover 4b, thereby renewing the ink within the nozzle N. Although not shown, the suction mechanism 4d includes a pressure-reducing tank and a pressure-reducing pump. The pressure-reducing tank is, for example, a metal chamber with a depressurized internal space, and is disposed within the housing 4a described above. The pressure-reducing tank communicates with the hole in the cover 4b described above and with the pressure-reducing pump. The pressure-reducing pump is a mechanism for depressurizing the pressure-reducing tank by venting air from it. In addition, valves for pressure regulation or opening / closing are respectively provided between the pressure-reducing tank and the cover 4b, and between the pressure-reducing tank and the pressure-reducing pump.

[0083] The wiping part 4e is a structure of a wiping device 4e1 disposed adjacent to the cover part 4b and having a function of wiping the nozzle surface F. Figure 4 In the example shown, the wiping part 4e is elongated and arranged parallel to the cover part 4b. Furthermore, when viewed from above, the wiping part 4e is positioned between the cover part 4b and the inspection part 4f. The wiping device 4e1 is an elastic scraper-shaped component made of rubber or elastomer material, which cleans the nozzle surface F of the head 3a by wiping it. Preferably, the wiping device 4e1 is bent so that its tip faces the cover part 4b. The wiping device 4e1 is fixed to the top surface 4c1 of the support platform 4c via the support body 4e2 and by screws or the like. Additionally, the ink removed from the nozzle surface F by the wiping part 4e is recovered by a recovery mechanism such as the grooves described above formed on the top surface 4c1, or a recovery tank (not shown).

[0084] The inspection unit 4f is a structure that supports a second medium W2, such as paper or film, having a surface WF2 for printing a test pattern, which is used to inspect the ink ejection function of the head 3a. Figure 4 In the example shown, the inspection unit 4f is box-shaped and has a mounting surface 4f1 for placing the second medium W2. Although not shown, the mounting surface 4f1 is provided with elements such as an adhesive layer or adsorption mechanism for fixing the position of the second medium W2. The test pattern is an image used to determine the presence or absence of defects such as clogging of the nozzle N of the head 3a based on visual inspection or imaging results from the camera device 3g. Furthermore, the content of the test pattern is arbitrary, as long as it enables this determination.

[0085] In the maintenance unit 4 described above, when viewed from above on the mounting surface 4f1, the cover part 4b, the wiper part 4e, and the inspection part 4f are arranged sequentially along a line segment perpendicular to the rotation axis O1 of the robotic arm 2. Therefore, as described later, the covering action, the wiping action, and the second printing action can be smoothly performed sequentially by the movement of the same three joints 230 as the first printing action.

[0086] 1-5. Operation of the 3D printing apparatus 1

[0087] Figure 5 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 1 according to the embodiment. Figure 5 As shown, firstly, in step S1, the stereolithography printing apparatus 1 determines whether a first printing instruction has been received. This determination is performed, for example, by the processing circuit 5b determining whether an execution instruction for printing the first medium W1 has been received from the computer 7.

[0088] Upon receiving the first printing instruction, the stereoscopic printing apparatus 1 performs a movement action in step S2. This movement action is an action that moves the head 3a to the execution start position of the first printing action, as described later, and is implemented by the processing circuit 5b controlling the drive of the robotic arm 2 based on the path information Da.

[0089] Following step S2, the stereolithography printing apparatus 1 performs a first printing action in step S3. This first printing action is the printing of ink onto the first medium W1 using ink from the head 3a. This action is performed by the processing circuit 5b controlling the drive of the robotic arm 2 based on path information Da, and by the control module 6 controlling the drive of the head 3a.

[0090] After step S3, or in the absence of a first printing instruction, the stereolithography printing apparatus 1 determines in step S4 whether a second printing instruction exists. This determination is performed, for example, by the processing circuit 5b determining whether an execution instruction for printing the second medium W2 has been sent from the computer 7. Alternatively, the processing circuit 5b may determine that a second printing instruction exists even if a predetermined time has elapsed without a first printing instruction, regardless of whether an execution instruction for printing the second medium W2 has been sent from the computer 7.

[0091] In the absence of a second printing instruction, the stereoscopic printing apparatus 1 returns to step S1 as described above. On the other hand, in the presence of a second printing instruction, the stereoscopic printing apparatus 1 performs a movement action in step S5. This movement action is an action that moves the head 3a to the starting position of the maintenance action (covering action, wiping action, or execution of the second printing action) described later, and is implemented by the processing circuit 5b controlling the drive of the robotic arm 2 based on the path information Da.

[0092] After step S5, the stereolithography printing apparatus 1 performs maintenance operations in step S6. These maintenance operations include step S6a of performing a covering operation, step S6b of performing a wiping operation, and step S6c of performing a second printing operation.

[0093] The covering action in step S6a involves covering the nozzle surface F of the head 3a with the cover part 4b, which is implemented by controlling the drive of the robotic arm 2 based on path information Da via the processing circuit 5b. During the covering action, a suction action performed by the suction mechanism 4d is performed as needed. The wiping action in step S6b involves wiping the nozzle surface F of the head 3a with the wiping part 4e, which is implemented by controlling the drive of the robotic arm 2 based on path information Da via the processing circuit 5b. The second printing action in step S6c involves printing a test pattern on the second medium W2 on the inspection part 4f using ink from the head 3a. This is implemented by controlling the drive of the robotic arm 2 based on path information Da via the processing circuit 5b, and by controlling the drive of the head 3a via the control module 6.

[0094] While the execution order of the actions included in step S6 is not particularly limited, the preferred order is the covering action in step S6a, the wiping action in step S6b, and the second printing action in step S6c. In this case, after eliminating defects such as nozzle N clogging by performing a suction action together with the covering action, the ink remaining on the nozzle surface F can be removed by the wiping action. Subsequently, by performing the second printing action, it is possible to determine whether the defects of nozzle N have been eliminated based on the printing results of the test pattern. Furthermore, since the cover part 4b, the wiping part 4e, and the inspection part 4f are arranged sequentially as described above, these actions can be performed smoothly by performing the covering action in step S6a, the wiping action in step S6b, and the second printing action in step S6c in sequence.

[0095] Furthermore, during the maintenance process, after the second printing action is executed, the camera device 3g captures an image of the test pattern on the second medium W2, and determines whether the defect of nozzle N has been eliminated based on the image result. If it is determined that the defect of nozzle N has not been eliminated, the covering action of step S6a, the wiping action of step S6b, and the second printing action of step S6c are executed again in sequence as needed.

[0096] Following step S6, the stereolithography printing apparatus 1 determines in step S7 whether an end instruction exists. This determination is performed, for example, by the processing circuit 5b determining whether an end instruction has been sent from the computer 7.

[0097] The 3D printing apparatus 1 returns to step S1 as described above if there is no end indication, and terminates the operation if there is an end indication. Furthermore, it is preferable that, in situations where ink ejection by the head 3a has not been performed for an extended period, and nozzle N defects are prone to occur, the maintenance operation of step S6 is performed before the first printing operation in step S3 to confirm in advance that the nozzle N defects have been eliminated.

[0098] Figure 6 This is a side view of robotic arm 2 during the execution of the first printing action in step S3. Figure 6 The example illustrates printing on surface WF1 of a first medium W1, wherein the first medium W1, being ellipsoidal in shape, is arranged such that its major axis AX is parallel to the X-axis. Here, the first medium W1 is positioned at a location closer to the robot arm 2 in the X2 direction. Furthermore, in... Figure 6 In the pose of head 3a shown by the solid line, the a-axis is parallel to the X-axis, the b-axis is parallel to the Y-axis, and the c-axis is parallel to the Z-axis.

[0099] like Figure 6 As shown, in the first printing action, the robotic arm 2 moves the head 3a along the movement path RU. The movement path RU is a path along the surface WF1 from position PS to position PE. The movement path RU is a straight line extending along the X-axis when viewed in the Z2 direction.

[0100] In the first printing action, the robotic arm 2 causes three of the six joints 230 to move. Figure 6 In the example shown, during the execution of the first printing action, the robotic arm 2 aligns the rotation axes of joints 230_2, 230_3, and 230_5 with the Y-axis and performs the actions of these joints. Thus, the head 3a can be stably moved along the movement path RU by the actions of the three joints 230.

[0101] Here, preferably, the robotic arm 2 controls the attitude of the head 3a based on the curvature of the surface WF1, keeping the spray direction of the ink from the head 3a relative to the surface WF1 fixed. Therefore, it is preferable that the yaw angle and tilt angle of the head 3a in the movement path RU are fixed values. On the other hand, it is preferable that the pitch angle of the head 3a in the movement path RU varies. That is, it is preferable that the pitch angles of the head 3a at the first position P1 and the second position P2, which are any two points in the movement path RU, are different from each other. In addition, in this embodiment, the movement path RU is set such that the ejection direction vector of the ink droplets ejected by the head 3a includes a component that is always vertically downward. In other words, the vector in the c2 direction includes a component in the Z2 direction. With such a setting of the movement path RU, since the head 3a will not eject ink droplets in a direction that opposes gravity, the flight of the ink droplets is more stable.

[0102] The above printing process is used to print on the workpiece W.

[0103] Here, the yaw, roll, and pitch angles of the head are explained. The yaw, roll, and pitch angles of head 3a are represented as rotations around the c-axis, a-axis, and b-axis relative to an arbitrarily set reference attitude of head 3a. Furthermore, in the reference attitude of head 3a, the relationships between the a-axis, b-axis, c-axis, and the X-axis, Y-axis, and Z-axis are fixed in a unique form.

[0104] The yaw angle of the head in the first posture of head 3a is represented as the amount of rotation about the c-axis required for the posture change from the reference posture to the first posture. This amount of rotation about the c-axis refers to the absolute value of the angle between the a-axis in the reference posture and the a-axis in the first posture when viewed along the c-axis direction in the reference posture. Alternatively, the amount of rotation about the c-axis refers to the absolute value of the angle between the b-axis in the reference posture and the b-axis in the first posture when viewed along the c-axis direction in the reference posture.

[0105] Similarly, the head tilt angle in the first posture of head 3a is represented as the amount of rotation about the a-axis required for the posture change from the reference posture to the first posture. This amount of rotation about the a-axis refers to the absolute value of the angle between the b-axis in the reference posture and the b-axis in the first posture when viewed along the direction of the a-axis in the reference posture. Alternatively, the amount of rotation about the a-axis refers to the absolute value of the angle between the c-axis in the reference posture and the c-axis in the first posture when viewed along the direction of the a-axis in the reference posture.

[0106] Similarly, the pitch angle of the head in the first posture of head 3a is represented as the amount of rotation about the b-axis required for the posture change from the reference posture to the first posture. This amount of rotation about the b-axis refers to the absolute value of the angle between the a-axis in the reference posture and the a-axis in the first posture when viewed along the direction of the b-axis in the reference posture. Alternatively, the amount of rotation about the b-axis refers to the absolute value of the angle between the c-axis in the reference posture and the c-axis in the first posture when viewed along the direction of the b-axis in the reference posture.

[0107] use Figure 6 Let's further explain the yaw, roll, and pitch angles of head 3a. For example, let's set the reference attitude of head 3a as an attitude where the a-axis is parallel to the X-axis, the b-axis is parallel to the Y-axis, and the c-axis is parallel to the Z-axis. At this point... Figure 6 The yaw, roll, and pitch angles of head 3a, as shown by the solid line, are all 0°. On the other hand, Figure 6 The pitch angle of head 3a, indicated by the dashed line, is approximately 45°, while the yaw and roll angles are 0°. In other words, Figure 6 The pitch angles of head 3a, shown by the solid line, and head 3a, shown by the dashed line, are different.

[0108] Figure 7 This is a top view of the three-dimensional printing apparatus 1 during the execution of the first printing action. Figure 7 In the posture of head 3a, shown by the solid line, axis a is parallel to the X-axis, axis b is parallel to the Y-axis, and axis c is parallel to the Z-axis. During the execution of the first printing action, as... Figure 7 As shown, when viewed from above the base 210, the arrangement direction DN of the plurality of nozzles N of the head 3a is orthogonal to the scanning direction DS of the head 3a in the aforementioned movement path RU. Here, when viewed from above the base 210, if the imaginary line segment connecting the head 3a and the base 210 during the execution of the first printing action is defined as the first line segment L1, the angle θ1 between the arrangement direction DN and the first line segment L1 is 90°. However, the angle θ1 is not limited to 90°, for example, it can be within the range of 70° to 110°. In addition, the first line segment L1 can be more strictly defined as the imaginary line segment connecting the center point of the nozzle surface F and the rotation axis O1 during the execution of the printing action when viewed from above the base 210.

[0109] After the first printing action is performed, the movement action described in step S5 above is carried out, thereby... Figure 7 As shown by the double-dotted line, head 3a moves onto cover 4b. Although in Figure 7 In the pose of head 3a, indicated by the double-dotted line, the c-axis is parallel to the Z-axis, but the angle between the a-axis and the X-axis is 45°, and the angle between the b-axis and the Y-axis is 45°.

[0110] Here, the reference attitude of head 3a is set as an attitude where the a-axis is parallel to the X-axis, the b-axis is parallel to the Y-axis, and the c-axis is parallel to the Z-axis. At this time, Figure 7 The yaw, roll, and pitch angles of head 3a, as shown by the solid line, are all 0°. On the other hand, Figure 7 The yaw angle of head 3a, indicated by the double-dotted line, is 45°, while the roll and pitch angles are 0°. In other words, Figure 7 The yaw angles of head 3a, shown by the solid line, and head 3a, shown by the double-dotted line, are different. In other words, the alignment direction DN of nozzle N, when viewed from any coordinate in the universal coordinate system towards the Z1 direction, is different during the printing action, after the moving action, or during the covering action. More specifically, the angle between the alignment direction DN during the printing action and the alignment direction DN after the moving action or during the covering action is 45°.

[0111] This movement is primarily performed when joint 230_1 is activated. While joints 230_2, 230_3, and 230_5, used in the printing action described above, could also be activated, it is preferable not to activate joints 230_4 and 230_6. In this case, the reproducibility of the robotic arm 2's movements in the first printing action can be improved when the first printing action is performed again.

[0112] Figure 8 A top view of the three-dimensional printing device 1 during the execution of maintenance operations. Figure 8 In the diagram, solid lines indicate the state of robotic arm 2 during the execution of the covering action, specifically the covering action, the wiping action, and the second printing action, performed sequentially. For example... Figure 8 As shown, when viewed from above the base 210, if the imaginary line segment connecting the head 3a and the base 210 during the execution of the covering action is defined as the second line segment L2, the angle θ2 between the arrangement direction DN and the second line segment L2 is 90°. However, the angle θ2 is not limited to 90°; for example, it can be within the range of 70° to 110°. Furthermore, the second line segment L2 can be more strictly defined as the imaginary line segment connecting the center point of the nozzle surface F and the rotation axis O1 during the execution of the covering action when viewed from above the base 210.

[0113] Here, when viewed from above the base 210, if the angle between the first line segment L1 and the second line segment L2 is set to θ3, the angles θ1, θ2, and θ3 satisfy the relationship |θ1-θ2| < θ3. Furthermore, from the viewpoint of reducing the twisting of the piping section 10 and the wiring section 11, it is preferable to make |θ1-θ2| as small as possible.

[0114] After the covering action is performed, the wiping action and the second printing action are performed sequentially. At this time, similar to the first printing action described above, the robotic arm 2 aligns the rotation axes of joints 230_2, 230_3, and 230_5 parallel to the Y-axis and actuates these joints. Thus, the head 3a can be stably moved along the movement path RU by the movement of the three joints 230. Although these three joints 230 are actuated during the execution of the second printing action, since the surface WF2 of the second medium W2 is planar, from the viewpoint of improving the image quality of the test pattern, it is preferable to fix not only the yaw angle and tilt angle of the head 3a, but also the pitch angle.

[0115] After the above maintenance actions are performed, the movement is completed via the movement action described in step S2 above. Figure 8 As shown by the double-dotted line, head 3a moves to the printing position described above. This movement, like the movement in step S5, is primarily performed when joint 230_1 is moved.

[0116] As described above, the stereolithography printing apparatus 1 has a head 3a and a robotic arm 2. The head 3a has a nozzle surface F, on which are arranged a nozzle array La and a nozzle array Lb, which are multiple nozzles N arranged to eject ink, an example of "liquid". The robotic arm 2 has a base 210 and an arm 220 that supports the head 3a. Joints 230_2 to 230_6, an example of "multiple rotating parts", are provided across the arm 220 from the base 210. By rotating the joints 230_2 to 230_6, the position of the head 3a relative to the base 210 changes.

[0117] Furthermore, as described above, the stereoscopic printing apparatus 1 performs the first printing action in step S3 and the second printing action in step S6c. In the first printing action of step S3, while the robotic arm 2 changes the position of the head 3a relative to the first medium W1, ink is ejected from the head 3a onto the first medium W1 to print an image. In the second printing action of step S6c, while the robotic arm 2 changes the position of the head 3a relative to the second medium W2 to a position different from the position during the execution of the first printing action, ink is ejected from the head 3a onto the second medium W2 to print a test pattern. Here, the yaw angle of the head 3a during the execution of the first printing action in step S3 is different from the yaw angle of the head 3a during the execution of the second printing action in step S6c.

[0118] In the above-described stereolithography printing apparatus 1, since a test pattern is printed on the second medium W2 through the execution of the second printing action, defects such as nozzle clogging can be judged based on the printing result. Therefore, if such defects exist, they can be improved before the execution of the first printing action. As a result, it is possible to prevent the printing of images with reduced image quality on the first medium W1 due to such defects during the execution of the first printing action. Furthermore, by making the yaw angle of the head 3a different during the execution of the first printing action in step S3 and the execution of the second printing action in step S6c, the amount of rotation of the joint 230_6 closest to the head among the multiple joints 230 of the robotic arm 2 can be reduced when the head 3a moves between the execution positions of these actions. As a result, damage caused by the twisting of wiring associated with the head 3a can be reduced. In addition, since the position of the head 3a is different during the execution of the first printing action and the second printing action, operations such as feeding or unloading of the first medium W1 can be performed during the execution of the second printing action. Therefore, even when performing the second printing action, the decrease in productivity of printing on the first medium W1 can be reduced.

[0119] In the 3D printing apparatus 1, it is preferable that when the two positions traversed by the head 3a during the execution of the first printing action in step S3 are designated as first position P1 and second position P2, the pitch angles at the first position P1 and the second position P2 of the head 3a are different from each other. In this case, even if the printing surface of the first medium W1 is curved or the like, the posture of the head 3a relative to the object portion of the printing surface can be kept fixed. Therefore, it has the advantage of easily improving image quality regardless of the shape of the printing surface of the first medium W1.

[0120] Preferably, the first printing action in step S3 includes changing the position of the head 3a relative to the first medium W1 while maintaining the yaw angle and tilt angle of the head 3a at fixed values. In this case, it is possible to reduce the unevenness of ink density ejected from the head 3a onto the first medium W1 during the execution of the first printing action in step S3. As a result, it has the advantage of easily improving image quality.

[0121] Similarly, preferably, the second printing action in step S6c includes changing the position of the head 3a relative to the second medium W2 while maintaining the yaw angle, tilt angle, and pitch angle of the head 3a at a fixed position. In this case, it is possible to reduce the unevenness of ink density when it is ejected from the head 3a onto the planar second medium W2 during the execution of the second printing action in step S6c. As a result, it has the advantage of easily improving the image quality of the test pattern. This advantage helps to improve the accuracy of the judgment based on the printing results of the test pattern.

[0122] Furthermore, as described above, the stereolithography printing apparatus 1 also performs the movement action in step S2 or step S5. During the movement action in step S2 or step S5, the robotic arm 2 moves the head 3a during the period between the execution of the first printing action in step S3 and the execution of the second printing action in step S6c. Therefore, the movement action in step S2 enables the transition from the second printing action in step S6c to the first printing action in step S3. Similarly, the movement action in step S5 enables the transition from the first printing action in step S3 to the second printing action in step S6c.

[0123] Furthermore, the amount of rotation of joint 230_6 during the execution of the movement action spanning step S2 or step S5 is smaller compared to the amount of rotation of joint 230_1 during the execution of the movement action spanning step S2 or step S5. Here, joint 230_1 is an example of a "first joint" and is the joint 230 closest to the base 210 among a plurality of joints 230. Joint 230_6 is an example of a "second joint" and is the joint 230 furthest from the base 210 among a plurality of joints 230. When joint 230_6 rotates, compared to the case where joint 230_1 rotates, it is easier for wiring components such as the supply pipe 10a and drive wiring 11a associated with the head 3a to twist. Therefore, by making the rotation of joint 230_6 during the execution of the movement action spanning step S2 or step S5 smaller than that of joint 230_1 during the execution of the movement action spanning step S2 or step S5, the twisting of the wiring component during the movement action of step S2 or step S5 can be reduced.

[0124] Furthermore, the difference between the yaw angle of the head unit 3a during the execution of the first printing action in step S3 and the yaw angle of the head unit 3a during the execution of the second printing action in step S6c is preferably 45° or more, and more preferably 90° or more. Thus, the larger the difference in yaw angle, the further the position of the first medium W1 during the execution of the first printing action in step S3 is from the position of the head unit 3 during the execution of the second printing action in step S6c. Therefore, interference with the head unit 3 can be suppressed when operations such as setting or removing the first medium W1 and adjusting the position of the first medium W1 are performed during the execution of the second printing action.

[0125] Furthermore, as mentioned above, the stereolithography printing apparatus 1 also includes an imaging device 3g, which is supported on the arm 220 in a fixed position relative to the head 3a, and captures images of the test pattern. Therefore, the defect of the nozzle N can be determined based on the imaging results of the imaging device 3g.

[0126] Here, as described above, the imaging device 3g has a rectangular pixel area composed of multiple pixels, and the long side of this pixel area is parallel to the arrangement direction DN of the multiple nozzles N. Therefore, the test pattern can be effectively imaged by the imaging device 3g.

[0127] Furthermore, as mentioned above, the imaging device 3g and the head 3a are arranged along the arrangement direction DN of the plurality of nozzles N. Therefore, contact between the imaging device 3g and the three-dimensional first medium W1 is prevented during the execution of the first printing action. In addition, it has the advantage of making it difficult for ink mist from the nozzles N to adhere to the imaging device 3g.

[0128] Furthermore, as described above, the stereolithography printing apparatus 1 also includes a cover portion 4b. The cover portion 4b is fixed relative to the base portion 210 and covers the nozzle surface F. Here, as described above, the stereolithography printing apparatus 1 also performs the covering action of step S6a. This covering action is performed by the robotic arm 2 positioning the head 3a at the position where the nozzle surface F is covered by the cover portion 4b. Therefore, even if the first printing action of step S3 is not performed for a long time, the thickening or curing of ink on the nozzle surface F can be reduced. As a result, clogging caused by ink from each nozzle N can be reduced.

[0129] Furthermore, as mentioned above, the lateral angle of head 3a during the execution of the second printing action in step S6c is equal to the lateral angle of head 3a during the execution of the covering action in step S6a. Therefore, the movement of the robotic arm 2 when repeatedly performing the covering action and the second printing action in an alternating manner can be simplified.

[0130] Furthermore, as described above, during the period between the execution of the covering action in step S6a and the execution of the second printing action in step S6c, the robotic arm 2 moves the head 3a in a direction orthogonal to the arrangement direction DN of the plurality of nozzles N during the execution of the covering action. Therefore, the movement of the robotic arm 2 when repeatedly performing the covering action and the second printing action in an alternating manner can be simplified.

[0131] Furthermore, as described above, the stereolithography printing apparatus 1 also includes a wiping unit 4e. The wiping unit 4e is positioned adjacent to the cover unit 4b and wipes the nozzle surface F. Here, the stereolithography printing apparatus 1 also performs the wiping action of step S6b. In this wiping action, the robotic arm 2 moves the head 3a so that the nozzle surface F is wiped by the wiping unit 4e. Therefore, it is possible to reduce contamination caused by ink on the nozzle surface F.

[0132] Here, as described above, during the covering action in step S6a, the cover portion 4b, the wiper portion 4e, and the second medium W2 are arranged sequentially along a direction orthogonal to the arrangement direction DN of the plurality of nozzles N. Therefore, the covering action, the wiping action, and the second printing action can be performed sequentially and effectively.

[0133] Furthermore, it has the advantage that when the first medium W1 is a non-absorbent medium that is less likely to absorb liquid from the head 3a compared to the second medium W2, and when the second medium W2 is a medium that is more likely to absorb liquid from the head 3a compared to the first medium W1, it is easier to improve the image quality of the test pattern in the second printing operation.

[0134] Furthermore, it has the following advantages: when the surface WF1 of the first medium W1 that is to be printed is three-dimensional and the surface WF2 of the second medium W2 that is to be printed is planar, it is not only easy to improve the image quality of the test pattern in the second printing action, but also easy to improve the imaging accuracy of the test pattern formed by the imaging device 3g.

[0135] 2. Variations

[0136] 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.

[0137] 2-1. Variation Example 1

[0138] While the structure of a six-axis vertical multi-axis robotic arm has been exemplified in the foregoing description, it is not limited to this structure. The robotic arm can be, for example, a vertical multi-axis robotic arm with axes other than six, or a horizontal multi-axis robotic arm. Furthermore, the arm portion of the robotic arm may have a telescopic mechanism in addition to a rotating portion consisting of a rotating mechanism. However, from the viewpoint of balancing print quality during printing operations with the degrees of freedom of the robotic arm's movement during non-printing operations, it is preferable that the robotic arm be a multi-axis robotic arm with six or more axes.

[0139] 2-2. Variation Example 2

[0140] Although the methods described above illustrate a structure for fixing the head relative to the robotic arm using screws or similar fastening mechanisms, this approach is not limited to that structure. For example, the head can also be fixed relative to the robotic arm by gripping it with a gripping mechanism such as a gripper that is mounted as an end effector of the robotic arm.

[0141] 2-3. Variation Example 3

[0142] 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.

[0143] 2-4. Variation Example 4

[0144] The application of the stereolithography printing apparatus of the present invention is not limited to printing. For example, the stereolithography printing apparatus that ejects a solution of color material can be used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Furthermore, the stereolithography printing apparatus that ejects a solution of conductive material can be used as a manufacturing apparatus for forming wiring or electrodes for wiring substrates. In addition, the stereolithography printing apparatus can also be used as a jet dispenser for applying liquids such as adhesives to a medium.

[0145] Symbol Explanation

[0146] 1…3D printing apparatus; 2…robotic arm; 2a…arm drive mechanism; 3…head unit; 3a…head; 3b…pressure regulating valve; 3c…curing light source; 3d…distance sensor; 3e…switch circuit; 3f…support body; 3g…camera device; 4…maintenance unit; 4a…housing; 4b…cover; 4b1…cover; 4b2…guide; 4b3…force application mechanism; 4c…support platform; 4c1…top surface; 4c2…foot; 4d…suction mechanism; 4d2…pressure reducing pump; 4e…wiping unit; 4e1…wiper; 4e2…support body; 4f…inspection unit; 4f1…placement surface; 5…controller; 5a…storage 5b… Processing circuit; 6… Control module; 6a… Timing signal generation circuit; 6b… Power supply circuit; 6c… Control circuit; 6d… Drive signal generation circuit; 7… Computer; 10… Piping section; 10a… Supply pipe; 11… Wiring section; 11a… Drive wiring; 210… Base; 220… Arm; 221… Arm; 222… Arm; 223… Arm; 224… Arm; 225… Arm; 226… Arm; 230… Joint (rotating part); 230_1… Joint (first rotating part); 230_2… Joint (rotating part); 230_3… Joint (rotating part); 230_4… Joint (Rotating part); 230_5…Joint (Rotating part); 230_6…Joint (Rotating part; Second rotating part); AX…Long axis; CLK…Clock signal; CNG…Exchange signal; Com…Drive signal; D1…Output; D3…Signal; DN…Arrangement direction; DS…Scanning direction; Da…Path information; F…Nozzle surface; FX1…Fixed position; FX2…Fixed position; FX3…Fixed position; FX4…Fixed position; L1…First line segment; L2…Second line segment; LAT…Latch signal; La…Nozzle array; Lb…Nozzle array; N…Nozzle; O1…Rotating axis; O2…Rotating axis; O3…Rotating axis; Moving shaft; O4…rotating shaft; O5…rotating shaft; O6…rotating shaft; P1…first position; P2…second position; PD…drive pulse; PTS…timing signal; RU…movement path; S1…step; S2…step; S3…step; S4…step; S5…step; S6…step; S6a…step; S6b…step; S6c…step; S7…step; SI…control signal; Sk1…control signal; VBS…offset potential; VHV…power supply potential; W1…first medium; W2…second medium; WF1…plane; WF2…plane; dCom…waveform specification signal; θ1…angle; θ2…angle.

Claims

1. A stereolithography apparatus characterized by, having: a head having a nozzle face on which a plurality of nozzle rows in which a plurality of nozzles that eject liquid are arranged are provided; a mechanical arm having a base and an arm portion that supports the head, and a plurality of turning portions are provided from the base to the arm portion, and the position of the head with respect to the base is changed by turning of the turning portions, the three-dimensional object printing apparatus executes a first printing operation and a second printing operation, wherein the first printing operation is an operation of printing an image by ejecting liquid from the head to a first medium while the mechanical arm changes the position of the head with respect to the first medium, and the second printing operation is an operation of printing a test pattern by ejecting liquid from the head to a second medium while the mechanical arm changes the position of the head with respect to the second medium to a position different from the position during execution of the first printing operation, the difference between the yaw angle of the head during execution of the first printing operation and the yaw angle of the head during execution of the second printing operation is 45° or more.

2. The three-dimensional object printing apparatus according to claim 1, wherein when two positions through which the head passes during execution of the first printing operation are set as a first position and a second position, the pitch angle of the head at the first position and the pitch angle of the head at the second position are different from each other.

3. The three-dimensional object printing apparatus according to claim 1 or 2, wherein the first printing operation includes an operation of changing the position of the head with respect to the first medium while maintaining the yaw angle and the roll angle of the head fixed.

4. The three-dimensional object printing apparatus according to claim 1, wherein the second printing operation includes an operation of changing the position of the head with respect to the second medium while maintaining the yaw angle, the roll angle, and the pitch angle of the head fixed.

5. The three-dimensional object printing apparatus according to claim 1, further comprising: an operation of moving the head by the mechanical arm during a period between the execution of the first printing operation and the execution of the second printing operation, in the plurality of turning portions, when a turning portion closest to the base is set as a first turning portion and a turning portion farthest from the base is set as a second turning portion, the amount of turning of the second turning portion across the execution period of the moving operation is smaller than the amount of turning of the first turning portion across the execution period of the moving operation.

6. The three-dimensional object printing apparatus according to claim 1, wherein the difference between the yaw angle of the head during execution of the first printing operation and the yaw angle of the head during execution of the second printing operation is 90° or more.

7. The three-dimensional object printing apparatus according to claim 1, further comprising: an imaging device that is supported on the arm portion in a fixed positional relationship with respect to the head, and that images the test pattern.

8. The stereoscopic object printing apparatus according to claim 7, wherein the camera has a rectangular pixel region composed of a plurality of pixels, wherein a long side direction of the pixel region is parallel to the arrangement direction of the plurality of nozzles.

9. The stereoscopic object printing apparatus according to claim 7 or 8, wherein the camera and the head are arranged along the arrangement direction of the plurality of nozzles.

10. The stereoscopic object printing apparatus according to claim 1, further comprising a cover portion whose position relative to the base portion is fixed and which covers the nozzle face, wherein the stereoscopic object printing apparatus further performs a covering operation of moving the head by the robot arm to a position at which the nozzle face is covered by the cover portion.

11. The stereoscopic object printing apparatus according to claim 10, wherein a yaw angle of the head during performance of the second printing operation is equal to a yaw angle of the head during performance of the covering operation.

12. The stereoscopic object printing apparatus according to claim 10 or 11, wherein the robot arm moves the head in a direction orthogonal to the arrangement direction of the plurality of nozzles during a period between performance of the covering operation and performance of the second printing operation.

13. The stereoscopic object printing apparatus according to claim 10, further comprising a wiper portion configured at a position adjacent to the cover portion and wiping the nozzle face, wherein the stereoscopic object printing apparatus further performs a wiping operation of moving the head by the robot arm so that the nozzle face is wiped by the wiper portion.

14. The stereoscopic object printing apparatus according to claim 13, wherein the cover portion, the wiper portion, and the second medium are sequentially arranged in a direction orthogonal to the arrangement direction of the plurality of nozzles during performance of the covering operation.

15. The stereoscopic object printing apparatus according to claim 1, wherein the first medium is a less-absorbent medium that is less likely to absorb liquid from the head than the second medium.

16. The stereoscopic object printing apparatus according to claim 1, wherein a face of the first medium that is a target of printing has a three-dimensional shape, and wherein a face of the second medium that is a target of printing has a planar shape. having: a head having a nozzle face on which a nozzle row in which a plurality of nozzles that eject liquid are arranged is provided; a robot arm having a base portion, an arm portion that supports the head, and a plurality of turning portions provided from the base portion to the arm portion, and changing a position of the head relative to the base portion by turning of the turning portions; and a camera supported on the arm portion in a manner fixed relative to the position of the head, and imaging a test pattern. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 17. A stereolithography apparatus characterized by, ​ ​ ​ ​ The stereoscopic object printing apparatus performs a first printing operation and a second printing operation, wherein the first printing operation is an operation of printing an image by ejecting a liquid from the head to a first medium while the mechanical arm changes the position of the head with respect to the first medium, and the second printing operation is an operation of printing a test pattern by ejecting a liquid from the head to a second medium while the mechanical arm changes the position of the head with respect to the second medium to a position different from the position during the execution of the first printing operation, the yaw angle of the head during the execution of the first printing operation is different from the yaw angle of the head during the execution of the second printing operation, the imaging device has a rectangular pixel region composed of a plurality of pixels, the long side direction of the pixel region is parallel to the arrangement direction of the plurality of nozzles.

18. A stereolithography apparatus characterized by, There is provided: a head having a nozzle face on which a nozzle row in which a plurality of nozzles that eject a liquid are arranged is provided; a mechanical arm having a base portion, an arm portion that supports the head, and a plurality of turning portions provided so as to span from the base portion to the arm portion, and changing the position of the head with respect to the base portion by turning of the turning portions, the stereoscopic object printing apparatus performs a first printing operation and a second printing operation, wherein the first printing operation is an operation of printing an image by ejecting a liquid from the head to a first medium while the mechanical arm changes the position of the head with respect to the first medium, and the second printing operation is an operation of printing a test pattern by ejecting a liquid from the head to a second medium while the mechanical arm changes the position of the head with respect to the second medium to a position different from the position during the execution of the first printing operation, the yaw angle of the head during the execution of the first printing operation is different from the yaw angle of the head during the execution of the second printing operation, the first medium is a difficult-to-absorb medium that is difficult to absorb the liquid from the head compared to the second medium.

19. A method of printing a three-dimensional object, the method comprising: There is provided: a head having a nozzle face on which a nozzle row in which a plurality of nozzles that eject a liquid are arranged is provided; a mechanical arm having a base portion, an arm portion that supports the head, and a plurality of turning portions provided so as to span from the base portion to the arm portion, and changing the position of the head with respect to the base portion by turning of the turning portions, in the stereoscopic object printing method, a first printing operation and a second printing operation are performed, wherein the first printing operation is an operation of printing an image by ejecting a liquid from the head to a first medium while the mechanical arm changes the position of the head with respect to the first medium, and the second printing operation is an operation of printing a test pattern by ejecting a liquid from the head to a second medium while the mechanical arm changes the position of the head with respect to the second medium to a position different from the position during the execution of the first printing operation, The difference between the yaw angle of the head during execution of the first printing operation and the yaw angle of the head during execution of the second printing operation is 45° or more.

Images