3D printing apparatus and 3D printing method

Abstract

This invention provides a three-dimensional printing apparatus and method for suppressing joint vibrations caused by head movement. The three-dimensional printing apparatus includes: a head that sprays liquid onto a three-dimensional workpiece; a robot including an arm and a base connected to one end of the arm, which changes the relative position of the workpiece and the head; the arm having a tip and multiple joints, the tip being the other end of the arm and supporting the head; and performing a first printing action in which the robot moves the position of the head while spraying liquid from the head, wherein during the execution of the first printing action, the head moves away from the base.

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 using an inkjet method. For example, Patent Document 1 discloses a three-dimensional printing apparatus having a head that ejects liquid such as ink onto the workpiece and a robot that changes the relative position of the workpiece and the head. The robot has an arm and a base connected to one end of the arm. The arm has a tip and multiple joints, the tip being the other end of the arm and supporting the head.

[0003] However, in the aforementioned existing technologies, there is a possibility that vibrations may occur in the joints during the printing process due to head movement, leading to a deterioration in print quality.

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

[0005] To address the above-mentioned issues, one embodiment of the three-dimensional printing apparatus of the present invention comprises: a head that sprays liquid onto a three-dimensional workpiece; a robot including an arm and a base connected to one end of the arm, which changes the relative position of the workpiece and the head, the arm having a tip and multiple joints, the tip being the other end of the arm and supporting the head, the three-dimensional printing apparatus performing a first printing action in which the robot moves the position of the head while the liquid is sprayed from the head, during the execution of the first printing action, the head moving away from the base.

[0006] Furthermore, one embodiment of the three-dimensional printing apparatus according to the present invention includes: a head that sprays liquid onto a three-dimensional workpiece; a robot comprising an arm and a base connected to one end of the arm, and capable of changing the relative position of the workpiece and the head, the arm having a tip and a plurality of joints, the tip being the other end of the arm and supporting the head, the three-dimensional printing apparatus performing a printing action in which the robot moves the position of the head while spraying liquid from the head, the plurality of joints including a first joint, a second joint, and a third joint, the second joint being closer to the base than the first joint, and the third joint being closer to the base than the first joint. At the top end, the first joint rotates around a first rotation axis, the second joint rotates around a second rotation axis, and the third joint rotates around a third rotation axis. The robot is capable of making the first rotation axis, the second rotation axis, and the third rotation axis parallel to each other. When the line segment connecting the second joint and the first joint is set as a first imaginary line segment, the line segment connecting the first joint and the third joint is set as a second imaginary line segment, and the angle formed by the first imaginary line segment and the second imaginary line segment is set as a first angle, the first angle at the time when the head begins to spray liquid during the printing action is less than 140 degrees.

[0007] One aspect of the three-dimensional printing method of the present invention uses a head and a robot. The head sprays liquid onto a three-dimensional workpiece. The robot includes an arm and a base connected to one end of the arm, and changes the relative position of the workpiece and the head. The arm has a tip and multiple joints. The tip is the other end of the arm and supports the head. In the three-dimensional printing method, a first printing action is performed whereby the robot moves the position of the head while liquid is sprayed from the head. During the execution of the first printing action, the head moves away from the base.

[0008] Furthermore, one aspect of the three-dimensional printing method of the present invention utilizes a head and a robot. The head sprays liquid onto a three-dimensional workpiece. The robot includes an arm and a base connected to one end of the arm, and changes the relative position of the workpiece and the head. The arm has a tip and multiple joints. The tip is the other end of the arm and supports the head. In the three-dimensional printing method, a printing action is performed whereby the robot moves the position of the head while liquid is sprayed from it. The multiple joints include a first joint, a second joint, and a third joint. The second joint is closer to the base than the first joint, and the third joint is closer to the base than the first joint. A joint is close to the top end. The first joint rotates around a first rotation axis, the second joint rotates around a second rotation axis, and the third joint rotates around a third rotation axis. The robot is able to make the first rotation axis, the second rotation axis, and the third rotation axis parallel to each other. When the line segment connecting the second joint and the first joint is set as a first imaginary line segment, the line segment connecting the first joint and the third joint is set as a second imaginary line segment, and the angle formed by the first imaginary line segment and the second imaginary line segment is set as a first angle, the first angle at the time when the head begins to spray liquid during the printing action is less than 140 degrees. Attached Figure Description

[0009] Figure 1 A perspective view showing the outline of the three-dimensional printing apparatus 100 according to the first embodiment.

[0010] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 100 according to the first embodiment.

[0011] Figure 3 This is a perspective view showing the outline structure of the liquid ejection unit 300 in the first embodiment.

[0012] Figure 4 This is a flowchart illustrating the process of the three-dimensional printing method according to the first embodiment.

[0013] Figure 5 This is a diagram illustrating the movement path RU of the head 310 relative to the workpiece W in the first embodiment.

[0014] Figure 6 This is a diagram illustrating the movement path RU of the head 310 relative to the workpiece W in the first embodiment.

[0015] Figure 7 This is a diagram showing robot 200 in a position ΔX of 1m.

[0016] Figure 8A diagram showing robot 200 in a position ΔX of 1.41m.

[0017] Figure 9 A diagram showing robot 200 in a position ΔX of 1.88m.

[0018] Figure 10 This is a diagram showing robot 200 in a position ΔX of 2m.

[0019] Figure 11 This is a diagram used to illustrate the relationship between the first angle θ1 and the position ΔX, and the relationship between the second angle θ2 and the position ΔX.

[0020] Figure 12 This is a diagram illustrating the intensity of vibration of joint 230_1 in the first embodiment.

[0021] Figure 13 A diagram illustrating the intensity of vibration of joint 230_1 in a manner that the head 310 moves toward the base 210.

[0022] Figure 14 This is a block diagram illustrating the electrical structure of the stereolithography printing apparatus 100A according to the second embodiment.

[0023] Figure 15 This is a flowchart illustrating the process of the three-dimensional printing method according to the second embodiment.

[0024] Figure 16 This is a diagram illustrating the movement path when the first printing mode is selected.

[0025] Figure 17 This is a diagram illustrating the movement path when the second printing mode is selected. Detailed Implementation

[0026] 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 various parts in the drawings differ appropriately from actual dimensions, and some parts are shown schematically for ease of understanding. Furthermore, unless otherwise stated in the following description, the scope of the present invention is not limited to these embodiments.

[0027] The following explanation uses intersecting X, Y, and Z axes appropriately. Furthermore, a direction along the X-axis is referred to as the X1 direction, and the opposite direction is referred to as the X2 direction. Similarly, opposite directions along the Y-axis are referred to as the Y1 and Y2 directions. Furthermore, opposite directions along the Z-axis are referred to as the Z1 and Z2 directions.

[0028] Here, the X, Y, and Z axes are the coordinate axes of the base coordinate system defined in the space between the workpiece W (described later) and the base 210. Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis may not be a vertical axis. Furthermore, although the X, Y, and Z axes are typically orthogonal to each other, this is not a limitation, and there are cases where they are not orthogonal. For example, the X, Y, and Z axes may intersect each other at an angle between 80 degrees and 100 degrees.

[0029] 1. First Implementation Method

[0030] 1-1. Overview of a 3D printing apparatus

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

[0032] The workpiece W has a surface WF that becomes the object of printing. Figure 1 In the example shown, the workpiece W is a long, spherical rugby ball shaped around its major axis AX, and surface WF is a curved surface with variable curvature. In this embodiment, the workpiece W is configured such that its major axis AX is parallel to the X-axis. Furthermore, the workpiece W is not limited to a rugby ball. The shape or size of the workpiece W is not limited to... Figure 1 The example shown is an arbitrary one. For instance, the surface of workpiece W can also have a flat surface, a stepped surface, or a surface with concave and convex shapes. Furthermore, the orientation of workpiece W is not limited to... Figure 1 The example shown is an arbitrary setup.

[0033] exist Figure 1 In the example shown, the stereoscopic printing apparatus 100 is an inkjet printer using a vertical multi-joint robot. Specifically, as Figure 1 As shown, the 3D printing apparatus 100 includes a robot 200, a liquid ejection unit 300, a liquid supply unit 400, and a controller 600. Hereinafter, we will first describe in sequence... Figure 1 The various parts of the three-dimensional printing apparatus 100 shown will be briefly described.

[0034] Robot 200 is a moving mechanism that changes the position and orientation of the liquid ejection unit 300 relative to the workpiece W. Figure 1 In the example shown, robot 200 is a so-called six-axis vertical articulated robot. Specifically, robot 200 has a base 210 and an arm 220.

[0035] 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 BN, such as a floor surface, facing the Z1 direction, by means of screws or the like. Furthermore, the mounting surface BN for fixing the base 210 is not limited to... Figure 1 The examples shown could also be surfaces such as walls, ceilings, movable trolleys, etc.

[0036] Arm 220 is a six-axis robotic arm having a base end portion mounted on a base 210 and a tip portion that allows for three-dimensional changes in position and orientation relative to the base end portion. Specifically, arm 220 has arm components 221, 222, 223, 224, 225, and 226, which are connected in this order. Furthermore, arm 220 has multiple joints, i.e., multiple joints 230. Figure 1 In the example shown, there are six joints 230.

[0037] Additionally, arm component 221 corresponds to the base end, which is also equivalent to "one end of the arm". Arm component 226 corresponds to the "top end".

[0038] Arm component 221 is connected to base 210 via joint 230_1, enabling rotation about rotation axis O1. Arm component 222 is connected to arm component 221 via joint 230_2, enabling rotation about rotation axis O2. Rotation refers to bidirectional circular motion. Arm component 223 is connected to arm component 222 via joint 230_3, enabling rotation about rotation axis O3. Arm component 224 is connected to arm component 223 via joint 230_4, enabling rotation about rotation axis O4. Arm component 225 is connected to arm component 224 via joint 230_5, enabling rotation about rotation axis O5. Arm component 226 is connected to arm component 225 via joint 230_6, enabling rotation about rotation axis O6. Furthermore, in the following text, joints 230_1 to 230_6 may be referred to as joint 230.

[0039] Joints 230_1 to 230_6 are rotary joints capable of rotating about a rotation axis. Although the robot 200 in this embodiment only has rotary joints, it may also have one or more linear joints. When one arm component is connected to other arm components via linear joints, one arm component moves relative to the other arm components along an axis via linear joints.

[0040] Arm components 222 and 223 are components that extend in a direction perpendicular to the rotation axis O3. The extension direction of arm component 222 varies depending on one or both of the rotation angles of joints 230_1 and 230_2. The extension direction of arm component 223 varies depending on one or more of the rotation angles of joints 230_1, 230_2, and 230_3.

[0041] Here, arm component 223 is an example of a "first arm component". Arm component 222 is an example of a "second arm component". Joints 230_1 to 230_6 are an example of "multiple joints". Joint 230_3, which connects arm components 223 and 222, is an example of a "first joint". Rotation axis O3 is an example of a "first rotation axis". Joint 230_2 is an example of a "second joint". Rotation axis O2 is an example of a "second rotation axis". Joint 230_5 is an example of a "third joint". Rotation axis O5 is an example of a "third rotation axis". Joint 230_1 is an example of a "fourth joint". Rotation axis O1 is an example of a "fourth rotation axis". Joint 230_2 is closer to the base 210 than joint 230_3, and joint 230_5 is closer to arm component 226 than joint 230_3. The statement that joint 230_2 is closer to base 210 than joint 230_3 means that the length of arm 220 from joint 230_2 to base 210 is shorter than the length of arm 220 from joint 230_3 to base 210. Similarly, the statement that joint 230_5 is closer to arm component 226 than joint 230_3 means that the length of arm 220 from joint 230_5 to arm component 226 is shorter than the length of arm 220 from joint 230_3 to arm component 226.

[0042] Joints 230_1 to 230_6 are mechanisms that connect two adjacent arm components in a manner that allows one of them to rotate relative to the other. Although in Figure 1 Although not shown in the diagram, drive mechanisms are respectively provided on joints 230_1 to 230_6 to rotate one of two adjacent arm components relative to the other. These drive mechanisms include, for example, a motor that generates a driving force for the rotation, a reducer that outputs the driving force at a reduced speed, and an encoder such as a rotary encoder that measures the amount of motion, such as the angle of rotation. Furthermore, the assembly of these drive mechanisms corresponds to the following... Figure 2 The arm drive mechanism 240 is shown. Furthermore, the encoder corresponds to the one described later. Figure 2 The encoder 241 is shown in the figure.

[0043] Rotation axis O1 is a perpendicular axis to the mounting surface BN of the fixed base 210. 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.

[0044] Furthermore, for these rotating axes, "perpendicular" includes not only the case where the angle between the two rotating axes is strictly 90 degrees, but also the case where the angle between the two rotating axes deviates from 90 degrees within a range of approximately ±5 degrees. 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 degrees.

[0045] At the top end of the arm 220, i.e., the arm component 226, a liquid ejection unit 300 is mounted as an end effector in a fixed state by means of screws or the like.

[0046] The liquid ejection unit 300 is a device having a head 310 that ejects ink, as an example of liquid, toward the workpiece W. In this embodiment, in addition to the head 310, the liquid ejection unit 300 also has a pressure regulating valve 320 for regulating the pressure of the ink supplied to the head 310 and a sensor 330 for measuring the distance between itself and the workpiece W. Since they are fixed together on the arm member 226, their relative positions and postures are fixed.

[0047] The ink is not specifically limited to any particular type. Examples include water-based 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. Furthermore, the ink is not limited to solutions; it can also be an ink in which color materials are dispersed as a dispersant. Moreover, the ink is not limited to inks containing color materials; it can also be an ink containing conductive particles such as metal particles used to form wiring, etc., as a dispersant.

[0048] Although Figure 1 Not shown in the diagram, but the head 310 includes a piezoelectric element, a chamber for collecting ink, and a nozzle N communicating with the chamber. Here, the piezoelectric element is provided for each chamber, and by individually varying the pressure in each chamber, ink is ejected from the nozzle N corresponding to that chamber. Such a head 310 is obtained, for example, by bonding together multiple substrates, such as a silicon substrate, appropriately processed by etching, etc., using adhesives or the like. Furthermore, this piezoelectric element corresponds to the [described later]... Figure 2 The piezoelectric element 311 is shown. Alternatively, a heater that heats the ink in the chamber can be used instead of the piezoelectric element as a drive element for ejecting ink from the nozzle N.

[0049] The pressure regulating valve 320 is a valve mechanism that opens and closes according to the pressure of the ink in the head 310. By opening and closing, the pressure of the ink in the head 310 is maintained at a negative pressure within a predetermined range, thereby stabilizing the meniscus of the ink formed on the nozzle N.

[0050] Sensor 330 is an optical displacement sensor that measures the distance between head 310 and workpiece W.

[0051] The liquid supply unit 400 is a mechanism for supplying ink to the head 310. The liquid supply unit 400 has a liquid storage section 410 and a supply channel 420.

[0052] The liquid storage section 410 is a container for storing ink. The liquid storage section 410 is, for example, a bag-shaped ink bag formed of a flexible film.

[0053] The supply channel 420 is a channel for supplying ink from the liquid reservoir 410 to the head 310. A pressure regulating valve 320 is provided midway through the supply channel 420. Therefore, even if the positional relationship between the head 310 and the liquid reservoir 410 changes, the pressure fluctuation of the ink in the head 310 can be reduced.

[0054] The supply channel 420 is formed, for example, by the internal space of a tube. Here, the tube used for the supply channel 420 is made of an elastic material such as rubber and is flexible. Therefore, even if the position or posture of the head 310 changes while keeping the position and posture of the liquid storage section 410 fixed, ink can be supplied from the liquid storage section 410 to the pressure regulating valve 320.

[0055] Controller 600 is a robot controller that controls the drive of robot 200. Although in Figure 1 Although not shown in the diagram, a control module for controlling the ejection action of the liquid ejection unit 300 is electrically connected to the controller 600. A computer is connected to the controller 600 and the control module in a communicative manner. Furthermore, this control module corresponds to the one described later. Figure 2 The control module 500 is shown. This computer is equivalent to the one described later. Figure 2 The computer shown is 700.

[0056] 1-2. Electrical structure of the 3D printing apparatus 100

[0057] Figure 2This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 100 according to the first embodiment. Figure 2 The diagram shows the electrical structural elements within the structural elements of the three-dimensional printing apparatus 100. Furthermore, in... Figure 2 The diagram shows an arm drive mechanism 240 including encoders 241_1 to 241_6. The arm drive mechanism 240 is an assembly of the aforementioned drive mechanisms that actuate joints 230_1 to 230_6. Encoders 241_1 to 241_6 are arranged in a manner corresponding to joints 230_1 to 230_6, and the amount of motion, such as the rotation angle, of joints 230_1 to 230_6 is measured. Furthermore, in the following text, each encoder 241_1 to 241_6 is sometimes referred to as encoder 241.

[0058] like Figure 2 As shown, the stereolithography printing apparatus 100, in addition to the robot 200, liquid ejection unit 300, and controller 600 described above, also includes a control module 500 and a computer 700. Furthermore, the various electrical structural elements described below can be appropriately separated, partially incorporated into other structural elements, or integrally formed with other structural elements. For example, part or all of the functions of the control module 500 or controller 600 can be implemented by the computer 700 connected to the controller 600, or by other external devices such as a PC (personal computer) connected to the controller 600 via a network such as a LAN (Local Area Network) or the Internet.

[0059] The controller 600 has the function of controlling the drive of the robot 200 and generating a signal D3 for synchronizing the ejection action of the head 310 with the action of the robot 200. The controller 600 has a storage circuit 610 and a processing circuit 620.

[0060] The storage circuit 610 stores various programs executed by the processing circuit 620 and various data processed by the processing circuit 620. In addition, part or all of the storage circuit 610 may also be included in the processing circuit 620.

[0061] The storage circuit 610 stores path information Da. Path information Da represents the movement path that the head 310 should move. Specifically, path information Da includes information representing the path that the tool center point should move, where the tool center point represents the origin of the aforementioned tool coordinate system. Path information Da is represented, for example, using coordinate values ​​from a base coordinate system. Path information Da is determined based on workpiece information representing the position and shape of the workpiece W and is input from the computer 700 into the storage circuit 610.

[0062] Furthermore, the path information Da can represent one movement path or multiple movement paths. In the first embodiment, the path information Da will be described as representing one movement path.

[0063] The processing circuit 620 controls the movements of joints 230_1 to 230_6 based on the path information Da, and generates a signal D3. Specifically, the processing circuit 620 performs inverse kinematics calculation, converting the path information Da into motion quantities such as rotation angles and rotational speeds of each joint 230_1 to 230_6. Then, the processing circuit 620 outputs control signals Sk_1 to Sk_6 based on the respective output signals D1_1 to D1_6 of the encoders 241_1 to 241_6 included in the arm drive mechanism 240 of the robot 200, in a manner that makes the actual rotation angles and rotational speeds of each joint 230_1 to 230_6 the results of the above calculation. The control signals Sk_1 to Sk_6 correspond to each joint 230_1 to 230_6, and control the drive of the motors set on the corresponding joints 230. In addition, output signals D1_1 to D1_6 correspond to encoders 241_1 to 241_6, respectively. In the following text, each of the output signals D1_1 to D1_6 is sometimes referred to as output signal D1.

[0064] Furthermore, the processing circuit 620 generates signal D3 based on the output signal D1 from at least one of encoders 241_1 to encoders 241_6.

[0065] The processing circuit 620 includes, for example, one or more processors such as a CPU (Central Processing Unit).

[0066] The control module 500 is a circuit that controls the ejection action of the head 310 based on the signal D3 output from the controller 600 and the printing data Img from the computer 700. The control module 500 includes a timing signal generation circuit 510, a power supply circuit 520, a control circuit 530, and a drive signal generation circuit 540.

[0067] The timing signal generation circuit 510 generates a timing signal PTS based on signal D3. The timing signal generation circuit 510 is, for example, composed of a timer that starts generating the timing signal PTS upon detection of signal D3.

[0068] The power supply circuit 520 receives power from a commercial power supply not shown and generates various predetermined potentials. These potentials are appropriately supplied to various parts of the stereolithography apparatus 100. For example, the power supply circuit 520 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection unit 300. Furthermore, the power supply potential VHV is supplied to the drive signal generation circuit 540.

[0069] The control circuit 530 generates a control signal SI, a waveform specification signal dCom, a latch signal LAT, a clock signal CLK, and a conversion 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 540, while the other signals are input to the switching circuit 340 of the liquid ejection unit 300. The control circuit 530 may include, for example, one or more processors such as a CPU (Central Processing Unit).

[0070] The control signal SI is a digital signal used to specify the operating state of the piezoelectric element 311 of the head 310. Specifically, the control signal SI specifies to the piezoelectric element 311 whether to supply the drive signal Com (described later). By specifying this, for example, whether ink is ejected from the nozzle N corresponding to the piezoelectric element 311, or the amount of ink ejected from the nozzle N, can be specified individually. 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 conversion signal CNG, used in conjunction with the control signal SI, specify the timing of the drive of the piezoelectric element 311, thereby specifying the timing of ink ejection from the nozzle N. The clock signal CLK is a clock signal that serves as a reference synchronized with the timing signal PTS. The signals input to the switching circuit 340 of the liquid ejection unit 300 will be described below.

[0071] The drive signal generation circuit 540 is a circuit that generates drive signals Com for driving each piezoelectric element 311 of the head 310. Specifically, the drive signal generation circuit 540 includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 540, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 530 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 520, thereby generating the drive signal Com. Here, the waveform contained in the drive signal Com that is actually supplied to the piezoelectric element 311 is the drive pulse PD. The drive pulse PD is supplied from the drive signal generation circuit 540 to the piezoelectric element 311 via the switching circuit 340. The switching circuit 340 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.

[0072] The computer 700 has the function of supplying path information Da and other information to the controller 600, and the function of supplying printing data Img and other information to the control module 500. For example, the computer 700 generates path information Da based on workpiece information representing the position and shape of the workpiece W, and supplies the generated path information Da to the controller 600. In addition, the computer 700 in this embodiment is electrically connected to the sensor 330 mentioned above, and supplies information for correcting the path information Da to the controller 600 based on the signal D2 from the sensor 330. The computer 700 is, for example, a PC. Furthermore, the computer 700 functions as the control unit of the three-dimensional printing apparatus 100, and causes the robot 200 and the liquid ejection unit 300 to perform the first printing action and the second printing action described later via the controller 600 and the control module 500.

[0073] 1-3. Liquid ejection unit

[0074] Figure 3 This is a perspective view showing the outline structure of the liquid ejection unit 300 in the first embodiment.

[0075] The following explanation uses intersecting a-axis, b-axis, and c-axis as appropriate. Furthermore, a direction along the a-axis is called the a1 direction, and the opposite direction is called the a2 direction. Similarly, opposite directions along the b-axis are called the b1 and b2 directions. Furthermore, opposite directions along the c-axis are called the c1 and c2 directions.

[0076] Here, the a-axis, b-axis, and c-axis are the coordinate axes of the tool coordinate system set in the liquid ejection unit 300, and the relative positions and orientations of the X-axis, Y-axis, and Z-axis change due to the actions of the robot 200. Figure 3 In the example shown, the c-axis is an axis parallel to the aforementioned rotation axis O6. 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 ranging from 80 degrees to 100 degrees.

[0077] As described above, the liquid ejection unit 300 includes: a head 310, a pressure regulating valve 320, and a sensor 330. These are comprised of... Figure 3 The support body 350 is shown by the double-dotted line in the figure.

[0078] The support 350 is made of, for example, a metallic material and is a solid rigid body. Furthermore, although in Figure 3 The support body 350 is a flat box shape, but the shape of the support body 350 is not particularly limited and can be any shape.

[0079] The support 350 is mounted on the top of the arm 220, i.e., the arm component 226. Therefore, the head 310, the pressure regulating valve 320, and the sensor 330 are respectively fixed to the arm component 226.

[0080] exist Figure 3 In the example shown, the pressure regulating valve 320 is located in the c1 direction relative to the head 310. The sensor 330 is located in the a2 direction relative to the head 310.

[0081] The supply channel 420 is divided into an upstream channel 421 and a downstream channel 422 by a pressure regulating valve 320. That is, the supply channel 420 has an upstream channel 421 that connects the liquid storage section 410 to the pressure regulating valve 320, and a downstream channel 422 that connects the pressure regulating valve 320 to the head 310. Figure 3 In the example shown, a portion of the downstream flow channel 422 of the supply flow channel 420 is constituted by a flow channel component 422a. The flow channel component 422a has flow channels for dispensing ink from the pressure regulating valve 320 to multiple portions of the head 310. The flow channel component 422a is, for example, a laminate of multiple substrates made of resin material, and grooves or holes for ink flow channels are suitably provided on each substrate.

[0082] The head 310 has a nozzle face F and a plurality of nozzles N opening on the nozzle face F. Figure 3In the example shown, the normal direction of the nozzle surface F is the c2 direction. The plurality of nozzles N are divided into a first nozzle column La and a second nozzle column Lb arranged side by side at intervals along the a-axis. The first nozzle column La and the second nozzle column Lb are each a set 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 header 310 have a structure that is approximately symmetrical to each other along the a-axis.

[0083] However, for the plurality of nozzles N in the first nozzle column La and the plurality of nozzles N in the second nozzle column Lb, their positions 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. The following example illustrates a structure in which the plurality of nozzles N in the first nozzle column La and the plurality of nozzles N in the second nozzle column Lb are positioned consistent along the b-axis.

[0084] In this embodiment, the nozzle density of each nozzle N in each nozzle row along the b-axis is 300 npi (number of nozzles per inch). However, the invention is not limited to this, and a lower nozzle density is also possible, but from the viewpoint of print quality and efficiency, a nozzle density of 25 npi or higher is preferred. When using a head 310 with such a nozzle density, the effects of the invention become significant because it is easily affected by vibrations, as described later. Furthermore, to achieve such a nozzle density, the nozzles N in each nozzle row can also be arranged in an alternating configuration.

[0085] 1-4. Operation of the 3D printing apparatus 100 and the 3D printing method

[0086] Figure 4 This is a flowchart illustrating the process of the three-dimensional printing method according to the first embodiment. This three-dimensional printing method is performed using the aforementioned three-dimensional printing apparatus 100. Figure 4 As shown, the three-dimensional printing apparatus 100 sequentially performs the following steps: step S110, which involves performing a non-printing operation; step S120, which involves performing a first printing operation; and step S130, which involves performing a non-printing operation. Furthermore, Figure 4 The actions shown are executed by computer 700 via controller 600 and control module 500, which control robot 200 and liquid ejection unit 300.

[0087] The non-printing action in step S110 is an action in which the robot 200 changes the relative position of the head 310 relative to the workpiece W before the first printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, the robot 200 moving the head 310 to... Figure 5 as well as Figure 6 The actions shown include the printing start position PS and preparatory actions such as aligning rotation axes O2, O3, and O5 into a parallel state. "Rightly aligning rotation axes O2, O3, and O5" means that rotation axes O2 and O3 are parallel to each other, and rotation axes O3 and O5 are parallel to each other, and rotation axes O2 and O5 are also parallel to each other. In this non-printing action, all six joints 230 of the robot 200 can move, and the head 310 moves through the movement of a greater number of joints 230 compared to the first printing action.

[0088] In addition, the action of the robot 200 moving the head 310 to the printing start position PS includes an acceleration action that increases the moving speed of the head 310.

[0089] The first printing action in step S120 is the action of ejecting ink from the head 310 while the robot 200 changes the relative position of the head 310 relative to the workpiece W. Furthermore, during the execution of the first printing action, the head 310 moves away from the base 210. In the following description, "printing action" refers to the action of ejecting ink from the head 310 while the robot 200 changes the relative position of the head 310 relative to the workpiece W. "First printing action" is a printing action, specifically an action that moves the head 310 away from the base 210. In the first embodiment, the stereoscopic printing apparatus 100 performs one first printing action.

[0090] In this embodiment, "the head 310 moves away from the base 210" means that at the printing start time (when the first printing operation begins) and the printing end time (when the first printing operation ends), the straight-line distance between the head 310 and the base 210 at the printing end time is greater than the straight-line distance between the head 310 and the base 210 at the printing start time. Although in this embodiment, the head 310 may temporarily move towards the base 210 during the period from the printing start time to the printing end time, it is preferable that the head 310 moves away from the base 210 at no time. Furthermore, the start of the printing operation means that the head 310 begins to eject ink onto the workpiece W. Furthermore, the end of the printing operation means that the head 310 stops ejecting ink onto the workpiece W.

[0091] While the number of joints 230 that move during the first printing action is not particularly limited, it is preferable that the head 310 is moved during the first printing action by fewer joints 230 compared to non-printing actions. By moving fewer joints 230 compared to non-printing actions, the deviation of the actual movement path of the head 310 from the ideal movement path can be reduced. In the first printing action of this embodiment, the head 310 is moved by the movement of three of the six joints 230 of the robot 200. The first printing action will be described below.

[0092] The non-printing action in step S130 is an action in which the robot 200 changes the relative position of the head 310 relative to the workpiece W after the first printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, the robot 200 moving the head 310 from... Figure 5 as well as Figure 6 The actions include moving the printing end position PE to other positions. In this non-printing action, all six joints 230 of the robot 200 can be moved, and the head 310 is moved by the movement of a greater number of joints 230 compared to the first printing action.

[0093] Figure 5 as well as Figure 6 This is a diagram illustrating the movement path RU of the head 310 relative to the workpiece W in the first embodiment. Figure 5 as well as Figure 6 The example illustrates printing on surface WF of a workpiece W configured with its major axis AX parallel to the X-axis. Here, the workpiece W is positioned in the X2 direction relative to the robot 200.

[0094] like Figure 5 as well as Figure 6 As shown, in the first printing action, the robot 200 moves its head 310 along a movement path RU. The movement path RU is a path along the surface WF from the printing start position PS to the printing end position PE. When viewed from the Z2 direction, the movement path RU is a straight line extending along the X-axis. The movement path RU is the path shown by path information Da. The printing start position PS is located in the X1 direction compared to the printing end position PE. The printing start position PS is located closer to the base 210 compared to the printing end position PE. For example, the computer 700 generates path information Da indicating that the movement path RU is located closer to the base 210 than the printing end position PE.

[0095] In the first printing action, robot 200 moves three of its six joints 230. Figure 5 In the example shown, during the execution of the first printing action, the robot 200 sets the rotation axes of joints 230_2, 230_3, and 230_5 to be parallel to the Y-axis and causes these joints 230 to move. In this way, the head 310 can be moved along the movement path RU by the movement of the three joints 230.

[0096] During the execution of the first printing action, the robot 200 moves three of its six joints 230 in a manner that keeps the b-axis of the tool coordinate system and the Y-axis of the base coordinate system set in the liquid ejection unit 300 parallel to each other. In other words, during the execution of the printing action, the robot 200 keeps the first nozzle array La and the second nozzle array Lb parallel to the three moving joints 230. Furthermore, during the execution of the first printing action, the robot 200 keeps joints 230_1, 230_4, and 230_6, whose rotation axes are not parallel to the Y-axis, from moving.

[0097] exist Figure 5 The image shows the state of robot 200 at the start of the first printing action. Figure 6 The diagram shows the state of robot 200 at the end of the first printing action. As described above, during the execution of the first printing action, the head 310 moves away from the base 210. When describing the movement of the arm components during the execution of the first printing action, as... Figure 5 as well as Figure 6 As shown, during the execution of the first printing action, the head 310 moves in a manner that increases the angle θ1 formed by the arm component 223 and the arm component 222. The first angle θ1 is... Figure 5 The first angle θ shown 1S and Figure 6 The first angle θ shown 1E The general term. For example... Figure 5 as well as Figure 6 As shown, the first angle θ 1E Greater than the first angle θ 1SMore specifically, the first angle θ1 is, when viewed along the Y1 direction, the angle of rotation centered on the intersection of an imaginary straight line extending along the direction of arm member 222 until it overlaps with an imaginary straight line extending along the direction of arm member 223. In this embodiment, "the head 310 moves in a manner that increases the first angle θ1" means that at any first moment during the execution of the first printing action and at a second moment after the first moment during the execution of the first printing action, the magnitude of the first angle θ1 at the second moment is greater than or equal to the first angle θ1 at the first moment. In other words, the head 310 moves in a manner that monotonically increases the first angle θ1 in a general sense. The first angle θ at the beginning of the first printing action 1S Preferably below 140 degrees Celsius.

[0098] In addition, such as Figure 5 as well as Figure 6 As shown, the first angle θ1 can also be defined as the angle between the first imaginary line segment L1 and the second imaginary line segment L2. The first imaginary line segment L1 is the line segment connecting joint 230_2 and joint 230_3. The second imaginary line segment L2 is the line segment connecting joint 230_3 and joint 230_5. Here, since no other joints are provided between joints 230_2 and 230_3 of the arm 220, the relative positional relationship between joints 230_2 and 230_3 does not change. That is, the length of the first imaginary line segment L1 is always fixed. In addition, a joint 230_4 is provided between joints 230_3 and 230_5 of the arm 220. However, as mentioned above, since the rotation axis O4 is an axis perpendicular to the rotation axis O3, and the rotation axis O5 is an axis perpendicular to the rotation axis O4, the relative positional relationship between joints 230_3 and 230_5 does not change. In other words, the length of the second imaginary line segment L2 is always fixed.

[0099] Furthermore, during the execution of the first printing action, the head 310 moves in a manner that reduces the second angle θ2. The second angle θ2 is the angle formed by the first imaginary line segment L1 and the third imaginary line segment L3. The third imaginary line segment L3 is the line segment connecting joint 230_2 and joint 230_1. The second angle θ2 is... Figure 5 The second angle θ shown 2S and Figure 6 The second angle θ shown 2E The general term. For example... Figure 5 as well as Figure 6 As shown, the second angle θ 2E Less than the second angle θ 2SMore specifically, the second angle θ2 is the angle of rotation when the third imaginary line segment L3 rotates clockwise around the intersection of the third imaginary line segment L3 and the first imaginary line segment L1 until it overlaps with the first imaginary line segment L1. In this embodiment, "the head 310 moves in a manner that reduces the second angle θ2" means that at any first moment during the execution of the first printing action and at a second moment after the first moment during the execution of the first printing action, the magnitude of the second angle θ2 at the second moment is less than or equal to the second angle θ2 at the first moment. In other words, the head 310 moves in a manner that monotonically reduces the second angle θ2 in a generalized sense.

[0100] Furthermore, during the execution of the first printing action, since joint 230_1 does not move, the inclination of the third imaginary line segment L3 relative to the setting surface BN is fixed. Moreover, since no other joints are provided between joints 230_2 and 230_1 of the arm 220, the relative positional relationship between joints 230_2 and 230_1 does not change. In other words, the length of the third imaginary line segment L3 is always fixed.

[0101] During the execution of the first printing action, the rotation of joint 230_3 is greater than that of joint 230_2.

[0102] Furthermore, although the three-dimensional printing apparatus 100 sets the rotation axes O2, O3, and O5 to be parallel to each other in the first printing operation of this embodiment, it is not limited to this. For example, the rotation axes O2, O3, and O6 can also be set to be parallel to each other. In this case, the head 310 is moved along the movement path RU by the movement of joints 230_2, 230_3, and 230_6. In this case, it is necessary to make the liquid ejection unit 300 fixed relative to the arm member 226 in the same direction as the fixed direction of the liquid ejection unit 300. Figure 5 as well as Figure 6 The examples are different. For example, by fixing the liquid ejection unit 300 to the arm component 226 in such a way that the b-axis along which the nozzle array is located and the rotation axis O6 are parallel to each other, it is possible to perform the first printing action on the workpiece W on the movement path RU.

[0103] 1.5. Summary of the First Implementation Method

[0104] The stereolithography printing apparatus 100 in the first embodiment includes: a head 310 that sprays ink onto a stereolithic workpiece W; and a robot 200 that changes the relative position of the workpiece W and the head 310. The robot 200 includes an arm 220 and a base 210 connected to one end of the arm 220. The arm 220 includes: an arm member 226, which is the other end of the arm 220 and a top portion supporting the head 310; and a plurality of joints 230 disposed on the arm 220. The stereolithography printing apparatus 100 performs a first printing action in which the robot 200 moves the position of the head 310 while ink is sprayed from the head 310, during which the head 310 moves away from the base 210.

[0105] By moving the head 310 away from the base 210 during the execution of the first printing action, compared to moving the head 310 towards the base 210, vibrations of the joint 230 generated during printing can be suppressed. The reason for suppressing vibrations of the joint 230 generated during printing will be explained using... Figures 7 to 11 Let me explain.

[0106] exist Figures 7 to 10 For ease of explanation, the stereoscopic printing apparatus 100 is simplified for illustration. As part of this simplification, the length of arm component 222 is set to 1 meter, and the combined length of arm components 223 and 224 is also set to 1 meter. When viewed from the Y1 direction, the head 310 moves such that the rotation axes O2 and O5 are aligned in the Z-axis direction. Furthermore, in Figures 7 to 10 For ease of explanation, the following example is shown: the workpiece W is a flat plate parallel to the XY plane, and surface WF is shown as a surface parallel to the XY plane. As the first printing action, the head 310 moves along a movement path RU parallel to the X-axis from a printing start position PS 1 meter away from the base 210 in the X2 direction to a printing end position PE 2 meters away in the X2 direction. Figures 7 to 11 In this context, the origin will be set at the base 210 on the X-axis, and the position ΔX will be set at the head 310 on the X-axis for display. Additionally, in... Figures 7 to 10 For ease of explanation, the third imaginary line segment L3, viewed from the Y1 direction, is shown with an angle of 90 degrees relative to the setting surface BN. Furthermore, in... Figures 7 to 11 In Chinese, the symbol "°" is used to represent angles. Furthermore, in the following description and... Figures 7 to 11 In Chinese, meters are recorded as "m". Figure 11 The diagram shows the relationship between the first angle θ1 and the second angle θ2 and the position ΔX of the head 310 on the X-axis.

[0107] Figure 7 This is a diagram showing robot 200 in a position ΔX of 1m. Figure 8 A diagram showing robot 200 in a position ΔX of 1.41m. Figure 9 A diagram showing robot 200 in a position ΔX of 1.88m. Figure 10 This is a diagram showing robot 200 in a position ΔX of 2m.

[0108] exist Figure 7 The image shows the state of arm 220 after moderate bending, arm 220 as Figure 8 , Figure 9 , Figure 10 And to stretch, in Figure 10 The image shows the state of arm 220 when it is fully extended.

[0109] Since arm components 222 and 224 have the same length of 1m, when viewed along the Y1 direction, rotation axes O2, O3, and O5 can be considered as vertices of an isosceles triangle. According to the properties of an isosceles triangle, the second angle θ2 can be expressed as shown in equation (1).

[0110] θ2=acos(ΔX / 2)×180 / π+90 (1)

[0111] Here, acos() is the function for finding the inverse cosine. π represents pi. Furthermore, the first angle θ1 can be expressed using the second angle θ2 as shown in equation (2).

[0112] θ1=(180-θ2)×2 (2)

[0113] like Figure 7 As shown, with position ΔX = 1m, according to equation (1), the second angle θ2 is 150 degrees. Furthermore, according to equation (2), the first angle θ1 is 60 degrees.

[0114] like Figure 8 As shown, with a position ΔX of 1.41m, according to equation (1), the second angle θ2 is approximately 135 degrees. Furthermore, according to equation (2), the first angle θ1 is approximately 90 degrees.

[0115] like Figure 9 As shown, with a position ΔX of 1.88m, according to equation (1), the second angle θ2 is approximately 110 degrees. Furthermore, according to equation (2), the first angle θ1 is approximately 140 degrees.

[0116] like Figure 10As shown, with position ΔX = 2m, according to equation (1), the second angle θ2 is 90 degrees. Furthermore, according to equation (2), the first angle θ1 is 180 degrees.

[0117] Figure 11 This is a diagram used to illustrate the relationship between the first angle θ1 and the position ΔX, and the relationship between the second angle θ2 and the position ΔX. Figure 11 The first angular characteristic Cθ1 shown in the graph gc represents the value of the first angle θ1 corresponding to the position ΔX. Furthermore, the second angular characteristic Cθ2 shown in the graph gc represents the value of the second angle θ2 corresponding to the position ΔX. The horizontal axis of the graph gc represents the position ΔX, and the vertical axis of the graph gc uses degrees to represent angles.

[0118] Generally, vibration is unlikely to occur in joint 230 when rotation is stopped or at a fixed speed. However, it is easy to generate vibration in joint 230 when the rotation speed increases or decreases. Furthermore, once vibration occurs in joint 230, it is difficult to suppress. The vibration generated in joint 230 is transmitted to head 310 via arm 220, causing head 310 to vibrate. When head 310 vibrates, a difference occurs between the ideal path and the actual path of head 310, resulting in a decrease in print quality.

[0119] As shown by the first angular characteristic Cθ1, there is not necessarily a proportional relationship between the position ΔX of the head 310 on the X-axis and the first angle θ1. Specifically, since the inclination of the first angular characteristic Cθ1 is approximately fixed when the first angle θ1 is between 0 and 100 degrees, it can be considered that there is approximately a proportional relationship between the position ΔX and the first angle θ1. In the following description, for ease of explanation, the absolute value of the change in the first angle θ1 relative to the change in the position ΔX will be simply referred to as the "inclination of the first angular characteristic Cθ1".

[0120] For example, when the head 310 moves within the range of 0 to 100 degrees of the first angle θ1, and the change in position ΔX per unit time is fixed, since the tilt of the first angle characteristic Cθ1 is approximately fixed, it can be said that the change in the first angle θ1 per unit time is also approximately fixed. In other words, it can be considered that within the range of 0 to 100 degrees of the first angle θ1, there is approximately a proportional relationship between the moving speed of the head 310 on the X-axis and the rotational speed of the joint 230_3.

[0121] On the other hand, when the first angle θ1 is between 100 and 180 degrees, the tilt of the first angular characteristic Cθ1 will increase accordingly as the first angle θ1 increases. More specifically, the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 100 and 120 degrees is greater than the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 0 and 100 degrees. Furthermore, the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 120 and 140 degrees is greater than the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 100 and 120 degrees. Also, the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 140 and 180 degrees is greater than the tilt of the first angular characteristic Cθ1 when the first angle θ1 is between 120 and 140 degrees.

[0122] Therefore, when the head 310 moves within the range of 100 to 180 degrees from the first angle θ1, even if the movement speed of the head 310 on the X-axis is fixed, the rotational speed of the joint 230_3 will change accordingly as the first angle θ1 increases, thereby increasing the vibration generated in the joint 230_3. In other words, vibration is more likely to occur when the first angle θ1 is between 100 and 120 degrees compared to when it is between 0 and 100 degrees. Furthermore, vibration is more likely to occur when the first angle θ1 is between 120 and 140 degrees compared to when it is between 100 and 120 degrees. Additionally, vibration is more likely to occur when the first angle θ1 is between 140 and 180 degrees compared to when it is between 120 and 140 degrees.

[0123] As shown in the second angular characteristic Cθ2, the relationship between the position ΔX of the head 310 on the X-axis and the second angle θ2, similar to the relationship between the position ΔX and the first angle θ1, is not necessarily proportional. Since the inclination of the second angular characteristic Cθ2 is approximately constant when the second angle θ2 is between 130 and 180 degrees, it can be considered that there is an approximate proportional relationship between the position ΔX and the second angle θ2. In the following description, the absolute value of the change in the second angle θ2 relative to the change in the position ΔX will be simply referred to as the "inclination of the second angular characteristic Cθ2".

[0124] For example, if the head 310 moves within the range of 130 to 180 degrees at the second angle θ2, and the change in position ΔX per unit time is constant, since the tilt of the second angle characteristic Cθ2 is approximately constant, it can be said that the change in the second angle θ2 per unit time is also approximately constant. In other words, it can be considered that within the range of 130 to 180 degrees at the second angle θ2, there is approximately a proportional relationship between the moving speed of the head 310 on the X-axis and the rotational speed of the joint 230_2.

[0125] On the other hand, when the second angle θ2 is between 90 and 130 degrees, the absolute value of the tilt of the second angle θ2 will increase accordingly as the second angle θ2 decreases. Therefore, when the head 310 moves within the range of 90 to 130 degrees of the second angle θ2, even if the movement speed of the head 310 on the X-axis is fixed, the rotation speed of the joint 230_2 will change accordingly as the second angle θ2 decreases, thereby increasing the vibration generated in the joint 230_2. In other words, vibration is more likely to occur when the second angle θ2 is between 130 and 90 degrees compared to when the second angle θ2 is between 180 and 130 degrees. Furthermore, even when the second angle θ2 is between 130 and 90 degrees, the smaller the second angle θ2, that is, the closer the second angle θ2 is to 90 degrees, the more likely vibration is to occur.

[0126] As explained above, corresponding to the increase in the first angle θ1 and the decrease in the second angle θ2, i.e., the head 310 moving away from the base 210, the vibration generated in joints 230_3 and 230_2 will increase. Moreover, as mentioned above, once vibration occurs in joint 230, it is difficult to suppress the vibration. Therefore, in the case where the head 310 moves towards the base 210, the vibration generated at the beginning of the printing operation may sometimes remain during the execution of the printing operation, resulting in a decrease in print quality. On the other hand, since in the first embodiment, the head 310 moves away from the base 210 during the execution of the first printing operation, vibration only occurs near the end of the first printing operation. However, since the vibration after the end of the printing operation does not affect the print quality, the impact of vibration is limited compared to the case where vibration occurs at the beginning of the first printing operation.

[0127] Therefore, according to the first embodiment, by changing from a state where vibration is difficult to generate to a state where vibration is easy to generate, the impact of vibration during the execution of the first printing action can be reduced and the printing quality can be improved.

[0128] In addition, such as Figure 7 as well as Figure 8 The rigidity of arm 220 in its moderately bent state, as shown, is higher than that of arm 220 in the following state. Figure 10 The overall rigidity of arm 220 in its fully extended state, as shown. Therefore, compared to its moderately bent state, arm 220 is more prone to vibration in its fully extended state. In particular, when the weight of the liquid ejection unit 300 is close to the movable weight of arm 220, although robot 200 is prone to vibration in its fully extended state or a state close to it, the vibration of robot 200 can be suppressed by gradually extending arm 220.

[0129] In addition, although Figures 7 to 11 In this example, for simplicity, the surface WF of the workpiece W is represented as a surface parallel to the XY plane, and an example of moving the head 310 along the X-axis is shown as the first printing action. However, even in other examples, the vibrations generated in joints 230_3 and 230_2 will increase as the head 310 moves away from the base 210. The other examples mentioned above refer to, for example... Figure 1 This includes cases where the surface WF is a surface with non-fixed curvature, and cases where the moving path RU is inclined relative to the X-axis.

[0130] Furthermore, in the other examples described above, the joints performing the action can also include joints 230 other than joints 230_2, 230_3, and 230_5. As an example of such an example, in... Figure 1 In the configuration relationship between the robot 200 and the workpiece W, there are cases where the head 310 is used to scan the surface WF along the path of the Y axis when observing along the Z-axis direction.

[0131] use Figure 12 as well as Figure 13 The intensity of vibration of joint 230_1 during the execution of the first printing action is explained.

[0132] Figure 12 This is a diagram illustrating the intensity of vibration of joint 230_1 in the first embodiment. Figure 13 This diagram illustrates the intensity of vibration of joint 230_1 in a manner that causes head 310 to move toward base 210. Figure 12 The diagram shows the output signal D1_1 of encoder 241_1 during the execution of the first printing action. Figure 13 The output signal D1_1 of encoder 241_1 is shown in the manner in which the head 310 is moved toward the base 210 during the printing operation. In the first printing operation of this embodiment and in the printing operation in the manner in which the head 310 is moved toward the base 210, the motor of joint 230_1 is not operating, and no driving force is generated for rotating the arm member 221. However, due to the vibration generated in joint 230, the arm member 221 rotates by a very small amount around the rotation axis O1.

[0133] Figure 12 The curve ge1 shown represents the output signal D1_1 during the execution of the first printing action. The horizontal axis of curve ge1 represents the elapsed time since the start of the first printing action, and the vertical axis of curve ge1 represents the pulse value shown by encoder 241_1. Similarly, Figure 13The graph ge2 shown represents the output signal D1_1 during the execution of the printing action in which the head 310 moves toward the base 210. The horizontal axis of graph ge2 represents the elapsed time since the start of the first printing action, and the vertical axis of graph ge2 represents the pulse value shown by the output signal D1_1.

[0134] As shown in curves ge1 and ge2, the vibration generated in joint 230 causes arm component 221 to rotate slightly around the rotation axis O1, thus causing the pulse value to vibrate. A pulse value of 0 indicates that arm component 221 does not rotate, while a larger absolute value of the pulse value indicates that arm component 221 rotates significantly. Therefore, it can also be said that the amplitude of the pulse value vibration represents the intensity of the vibration generated in joint 230_1.

[0135] The maximum amplitude of the pulse value vibration in curve ge1 is amplitude w1, and the maximum amplitude of the pulse value vibration in curve ge2 is amplitude w2. Amplitude w1 is narrower than amplitude w2. Therefore, compared with the method in which the head 310 moves towards the base 210, the first embodiment can suppress the vibration generated in the joint 230 during the first printing action, thereby improving the printing quality.

[0136] Furthermore, arm 220 includes arm component 223 and arm component 222 connected to arm component 223, with arm component 222 positioned closer to base 210 than arm component 223. Arm 220 has a plurality of joints 230, including joint 230_3 connecting arm component 223 and arm component 222. During the execution of the first printing action, head 310 moves in a manner that increases the first angle θ1 formed by arm component 223 and arm component 222.

[0137] like Figure 11 As shown, when the first angle θ1 increases, even if the movement speed of the head 310 on the X-axis is fixed, the rotation speed of the joint 230_3 will change, thereby increasing the vibration generated in the joint 230_3. Therefore, by reducing the first angle θ1 in advance at the start time of the first printing action, and by moving the head 310 in a manner that increases the first angle θ1 during the execution of the first printing action, the vibration generated in the joint 230_3 during the execution of the first printing action can be suppressed, thereby improving the printing quality.

[0138] The arm 220 has multiple joints 230, including joints 230_3, 230_2, and 230_5. Joint 230_2 is closer to the base 210 than joint 230_3. Joint 230_5 is closer to the arm component 226 than joint 230_3. Joint 230_3 rotates about rotation axis O3. Joint 230_2 rotates about rotation axis O2. Joint 230_5 rotates about rotation axis O5. The robot 200 is capable of making rotation axes O3, O2, and O5 parallel to each other. When the line segment connecting joint 230_2 and joint 230_3 is set as the first imaginary line segment L1, the line segment connecting joint 230_3 and joint 230_5 is set as the second imaginary line segment L2, and the angle formed by the first imaginary line segment L1 and the second imaginary line segment L2 is set as the first angle θ1, during the execution of the first printing action, the head 310 moves in a way that increases the first angle θ1.

[0139] During the execution of the first printing action, the rotation of joint 230_3 is greater than that of joint 230_2. Therefore, during the execution of the first printing action, the head 310 can be moved by increasing the first angle θ1 while maintaining the posture of the head 310 relative to the workpiece W. Furthermore, since the vibration of joint 230_3, which has a larger rotation compared to joint 230_2, can be suppressed by moving the head 310 away from the base 210, the printing quality can be improved.

[0140] The arm 220 has multiple joints 230, including a joint 230_1 disposed between joint 230_2 and base 210. Joint 230_1 rotates about rotation axis O1. When the line segment connecting joint 230_2 and joint 230_1 is designated as a third imaginary line segment L3, and the angle formed by the first imaginary line segment L1 and the third imaginary line segment L3 is designated as a second angle θ2, during the execution of the first printing action, the head 310 moves in a manner that reduces the second angle θ2.

[0141] like Figure 11 As shown, when the second angle θ2 decreases, even if the movement speed of the head 310 on the X-axis is fixed, the rotation speed of the joint 230_2 will change, thereby increasing the vibration generated in the joint 230_2. Therefore, by increasing the second angle θ2 in advance at the start time of the first printing action and moving the head 310 in a manner that decreases the second angle θ2 during the execution of the first printing action, the vibration generated in the joint 230_2 during the execution of the first printing action can be suppressed, thereby improving the printing quality.

[0142] In addition, the arm 220 has a plurality of joints 230 including a joint 230_1 disposed between joint 230_2 and base 210, joint 230_1 rotating about rotation axis O1, and rotation axis O2 and rotation axis O1 being perpendicular to each other.

[0143] Furthermore, preferably, the first angle θ1 at the start of the first printing action is 140 degrees or less. For example... Figure 11 As shown, the tilt of the first angle characteristic Cθ1 when the first angle θ1 is between 140 and 180 degrees is greater than the tilt of the first angle characteristic Cθ1 when the first angle θ1 is between 0 and 140 degrees. Therefore, by making the first angle θ1 at the start of the first printing action less than 140 degrees, compared with the method where the first angle θ1 at the start of the first printing action is greater than 140 degrees, the vibration generated in the joint 230_3 can be suppressed, thereby improving the printing quality.

[0144] 2. Second Implementation Method

[0145] The difference between the stereolithography printing apparatus 100A in the second embodiment and the first embodiment is that, when performing multiple printing operations, it is possible to select between a first printing mode and a second printing mode. When the first printing mode is selected, the stereolithography printing apparatus 100A performs multiple first printing operations without performing the second printing operation. The second printing operation is a printing operation, and it is an operation in which the head 310 moves toward the base 210. In the following description, the printing operation is a general term for the first printing operation and the second printing operation. Furthermore, the printing mode is a general term for the first printing mode and the second printing mode. When the second printing mode is selected, the stereolithography printing apparatus 100A selects one or more first printing operations and performs one or more second printing operations. Preferably, the total number of times the first printing operation is performed when the first printing mode is selected and the total number of times the first printing operation and the second printing operation are performed when the second printing mode is selected are set to be the same.

[0146] In the following description, for ease of understanding, the second embodiment will be explained using an example of performing two printing operations. Therefore, when the first printing mode is selected, the stereolithography printing apparatus 100A performs two first printing operations, while when the second printing mode is selected, the stereolithography printing apparatus 100A performs one first printing operation and one second printing operation. When the second printing mode is selected, the stereolithography printing apparatus 100A can either perform the first printing operation first and then the second printing operation, or perform the second printing operation first and then the first printing operation. In the following description, when the second printing mode is selected, the example of the stereolithography printing apparatus 100A performing the second printing operation after the first printing operation will be used for explanation.

[0147] 2-1. Electrical Structure of a Three-Dimensional Printing Apparatus

[0148] Figure 14 This is a block diagram illustrating the electrical structure of the stereolithography printing apparatus 100A according to the second embodiment. The stereolithography printing apparatus 100A differs from the stereolithography printing apparatus 100 in that it has a computer 700A instead of a computer 700, a controller 600A instead of a controller 600, and a robot 200A instead of a robot 200.

[0149] The difference between computer 700A and computer 700 is that, in the case of performing multiple printing operations, it has the function of selecting a printing mode, either a first printing mode or a second printing mode, and the function of generating path information DaA in the second embodiment based on the selected printing mode. The difference between controller 600A and controller 600 is that it has a storage circuit 610A instead of a storage circuit 610. The difference between storage circuit 610A and storage circuit 610 is that it has path information DaA instead of path information Da. Path information DaA represents the movement path RU of the first printing operation and the movement path RU of the second printing operation. The difference between robot 200A and robot 200 is that it moves the head 310 based on the path information DaA.

[0150] 2-2. Operation of the 3D printing apparatus 100A and the 3D printing method

[0151] Figure 15 This is a flowchart illustrating the process of the three-dimensional printing method according to the second embodiment. This three-dimensional printing method is performed using the aforementioned three-dimensional printing apparatus 100A.

[0152] In step S210, the computer 700A selects one of the first printing mode and the second printing mode based on any one of the three methods shown below.

[0153] In the first method, the computer 700A selects a printing mode based on the size of the workpiece W. Specifically, since the first angle θ1 does not increase and the vibration generated in the joint 230_3 is unlikely to increase when the size of the workpiece W is less than a predetermined threshold, the computer 700A selects a second printing mode. On the other hand, since the first angle θ1 increases when the size of the workpiece W is above the predetermined threshold, the computer 700A selects a first printing mode.

[0154] In the second method, computer 700A selects one of a first printing mode and a second printing mode based on user input. For example, computer 700A displays an image on its display device, allowing the user to specify either a "quality priority mode" or a "speed priority mode" as an option during printing. The user uses one or both of computer 700A's input devices, such as a mouse and a keyboard, to specify either the "quality priority mode" or the "speed priority mode." Computer 700A selects the first printing mode if the user specifies the "quality priority mode," and selects the second printing mode if the user specifies the "speed priority mode."

[0155] In the third method, when the recording duty cycle is higher than a predetermined ratio, the computer 700A selects the first printing mode. On the other hand, when the recording duty cycle is lower than the predetermined ratio, the computer 700A selects the second printing mode. This is because when the recording duty cycle is higher than the predetermined ratio, when print quality deteriorates, the deteriorated areas are more easily noticed, thus making the impact on image quality more apparent.

[0156] After the processing in step S210 is completed, in step S220, the computer 700A determines whether the selected printing mode is the first printing mode. If the determination result in step S220 is affirmative, that is, if the first printing mode is selected, the computer 700A generates path information DaA in step S230. This path information DaA represents the movement path in which the head 310 moves away from the base 210 during the first and second printing actions. Figure 16 This is an example of the movement path when the first printing mode is selected.

[0157] Figure 16This is a diagram illustrating the movement path when the first printing mode is selected. Figure 16 The diagram shows the movement paths RU1a for the first printing action and RU2a for the second printing action, as indicated by path information DaA when observing the XYZ space from the Z2 direction. Additionally, in... Figure 16 In order to facilitate understanding of the positional relationship between the movement path RU1a and the movement path RU2a, the surface WF that becomes the printing object and the base 210 of the robot 200A are shown.

[0158] like Figure 16 As shown, in the first printing mode, the printing start position PS1a of the movement path RU1a is closer to the base 210 than the printing end position PE1a, and the printing start position PS2a of the movement path RU2a is closer to the base 210 than the printing end position PE2a.

[0159] Return to the instructions Figure 15 After the processing in step S230 is completed, the computer 700A supplies path information DaA to the controller 600A. The controller 600A causes the storage circuit 610A to store the supplied path information DaA. After the storage circuit 610A stores the path information DaA, in step S240, the controller 600A causes the robot 200A to perform a non-printing action. The non-printing action in step S240 is an action in which the robot 200A changes the relative position of the head 310 relative to the workpiece W before the first printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, a preparatory action such as the robot 200A moving the head 310 to the printing start position PS1a of the first printing action while simultaneously making the rotation axes O2, O3, and O5 parallel to each other. In this non-printing action, all six joints 230 of the robot 200A can move, and the head 310 can move by moving a greater number of joints 230 than in the first printing action.

[0160] After the processing in step S240 is completed, in step S250, the controller 600A causes the robot 200A to perform the first printing action based on the path information DaA. After the processing in step S250 is completed, in step S260, the controller 600A performs a non-printing action. The non-printing action in step S260 is an action in which the robot 200A changes the relative position of the head 310 relative to the workpiece W after the first printing action and before the second first printing action. This non-printing action includes preparatory actions such as moving the head 310 from the printing end position PE1a to the printing start position PS2a of the second first printing action while simultaneously making the rotation axes O2, O3, and O5 parallel to each other. In this non-printing action, all six joints 230 of the robot 200A can move, and the head 310 is moved by the movement of a greater number of joints 230 compared to the first printing action.

[0161] After the processing in step S260 is completed, in step S270, the controller 600A causes the robot 200A to perform the second first printing action based on the path information DaA. After the processing in step S270 is completed, in step S280, the controller 600A performs a non-printing action. The non-printing action in step S280 is an action in which the robot 200A changes the relative position of the head 310 relative to the workpiece W after the second first printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, actions such as the robot 200A moving the head 310 from the printing end position PE2a to other positions. In this non-printing action, all six joints 230 of the robot 200A can be moved, and the head 310 is moved by the movement of more joints 230 than in the first printing action. After the processing in step S280 is completed, the stereolithography printing apparatus 100A ends. Figure 15 The series of processes shown. Additionally, Figure 15 The actions shown are executed by computer 700A via controller 600A and control module 500, which control robot 200A and liquid ejection unit 300.

[0162] If the determination result in step S220 is negative, that is, if the second printing mode is selected, the computer 700A generates path information DaA in step S310. This path information DaA represents a movement path in the first printing operation where the head 310 moves away from the base 210, and in the second printing operation, it represents a movement path in the second printing operation where the head 310 moves towards the base 210. Using... Figure 17This is an example of the movement path when the second printing mode is selected.

[0163] Figure 17 This is a diagram illustrating the movement path when the second printing mode is selected. Figure 17 The diagram shows the movement paths RU1b and RU2b of the first printing action, as shown in the path information DaA when observing the XYZ space from the Z2 direction. Additionally, in... Figure 17 In order to make it easier to understand the positional relationship between the movement path RU1b and the movement path RU2b, the face WF that becomes the printing object and the base 210 of the robot 200A are shown.

[0164] like Figure 17 As shown, in the second printing mode, the printing start position PS1b of the moving path RU1b is closer to the base 210 than the printing end position PE1b, and the printing start position PS2b of the moving path RU2b is farther from the base 210 than the printing end position PE2b.

[0165] like Figure 16 as well as Figure 17 As shown, the movement path RU1a when the first printing mode is selected is the same as the movement path RU1b when the second printing mode is selected. On the other hand, the movement path RU2a when the first printing mode is selected and the movement path RU2b when the second printing mode is selected are different. More specifically, the printing start position PS2a of movement path RU2a coincides with the printing end position PE2b of movement path RU2b, and the printing end position PE2a of movement path RU2a coincides with the printing start position PS2b of movement path RU2b. The trajectory of the head 310 following movement path RU2a is approximately the same as the trajectory of the head 310 following movement path RU2b.

[0166] Return to the instructions Figure 15After the processing in step S310 is completed, the computer 700A supplies path information DaA to the controller 600A. The controller 600A causes the storage circuit 610A to store the supplied path information DaA. After the storage circuit 610A stores the path information DaA, in step S320, the controller 600A causes the robot 200A to perform a non-printing action. The non-printing action in step S320 is an action in which the robot 200A changes the relative position of the head 310 relative to the workpiece W before the first printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, a preparatory action such as the robot 200A moving the head 310 to the printing start position PS1b of the first printing action while simultaneously making the rotation axes O2, O3, and O5 parallel to each other. In this non-printing action, all six joints 230 of the robot 200A can move, and the head 310 is moved by the movement of a greater number of joints 230 than in the first printing action.

[0167] After the processing in step S320 is completed, in step S330, the controller 600A, based on the path information DaA, causes the robot 200A to perform the first printing action. After the processing in step S330 is completed, in step S340, the controller 600A performs a non-printing action. The non-printing action in step S340 is an action in which the robot 200A changes the relative position of the head 310 with respect to the workpiece W after the first printing action and before the second printing action. This non-printing action includes preparatory actions such as moving the head 310 from the printing end position PE1b to the printing start position PS2b of the second printing action while simultaneously aligning the rotation axes O2, O3, and O5 into a parallel state. In this non-printing action, all six joints 230 of the robot 200A can be moved, and the head 310 is moved by the movement of a greater number of joints 230 compared to the first printing action.

[0168] like Figure 16 as well as Figure 17 As shown, the distance dm2 from the printing end position PE1b to the printing start position PS2b is shorter than the distance dm1 from the printing end position PE1a to the printing start position PS2a. Therefore, it can also be said that the movement distance of the head 310 in the non-printing action of step S340 is shorter than the movement distance of the head 310 in the non-printing action of step S260. Since the time spent on the movement of the head 310 is shorter, the time spent on the non-printing action of step S340 is shorter than the time spent on the non-printing action of step S260.

[0169] After the processing in step S340 is completed, in step S350, the controller 600A causes the robot 200A to perform a second printing action based on the path information DaA. The first angle θ1 at the start of the second printing action is preferably 140 degrees or less. Furthermore, it is preferable that the first angle θ1 at the start of the acceleration action included in the non-printing actions to be performed before the second printing action is 140 degrees or less.

[0170] Furthermore, although in the second printing operation, the three-dimensional printing apparatus 100A sets the rotation axes O2, O3, and O5 to be parallel to each other, just as in the first printing operation, it is not limited to this. For example, the rotation axes O2, O3, and O6 may also be set to be parallel to each other. Additionally, the second printing operation may also be performed with the rotation axes O2, O3, and O5 not parallel to each other.

[0171] After the processing in step S350 is completed, in step S360, the controller 600A performs a non-printing action. The non-printing action in step S360 is an action in which the robot 200A changes the relative position of the head 310 relative to the workpiece W after the second printing action. In this non-printing action, the head 310 does not eject ink. This non-printing action includes, for example, actions such as the robot 200A moving the head 310 from the printing end position PE2b to other positions. In this non-printing action, all six joints 230 of the robot 200A can move, and the head 310 is moved by the movement of a greater number of joints 230 compared to the second printing action. After the processing in step S360 is completed, the stereolithography printing apparatus 100A ends. Figure 15 The series of processes shown.

[0172] 2.3. Summary of the Second Implementation Method

[0173] In the second embodiment, the stereolithography printing apparatus 100A can select between a first printing mode and a second printing mode when performing multiple printing actions in which ink is ejected from the head 310 and the robot 200A moves the position of the head 310. When the first printing mode is selected, the stereolithography printing apparatus 100A performs multiple first printing actions without performing the second printing action; when the second printing mode is selected, it performs one or more first printing actions and one or more second printing actions. The second printing action is the movement of the robot 200A moving the position of the head 310 while ink is ejected from the head 310, during which the head 310 moves towards the base 210.

[0174] In the first printing mode, since the head 310 moves only in the direction away from the base 210 during multiple printing operations, the time required to complete multiple printing operations is longer compared to the second printing mode. However, vibrations generated in the joint 230 can be suppressed, thereby improving print quality. On the other hand, in the second printing mode, the head 310 moves both in the direction away from the base 210 and in the direction approaching the base 210. Therefore, in the second printing mode, although print quality decreases due to vibrations generated in the joint 230 in the direction approaching the base 210 compared to the first printing mode, the time required to complete multiple printing operations is shortened.

[0175] Furthermore, it is preferable that the first angle θ1 at the start of the second printing action is 140 degrees or less. By keeping the first angle θ1 at the start of the second printing action below 140 degrees, the rotational speed of the joint 230_3 is also relatively constant, given that the movement speed of the head 310 on the X-axis is fixed. Therefore, vibrations generated in the joint 230_3 can be suppressed, thereby improving print quality.

[0176] Furthermore, more preferably, the first angle θ at the start of the acceleration action included in the non-printing action to be performed before the second printing action is... 1S It is below 140 degrees. This is because the initial angle θ at the start of the acceleration is... 1S When the angle is greater than 140 degrees, the vibration generated in joint 230_3 becomes larger, and the vibration also remains in the second printing action after the acceleration action ends, resulting in a decrease in printing quality.

[0177] Furthermore, similar to the first embodiment, it is preferable that the first angle θ1 at the start of the first printing action is 140 degrees or less.

[0178] Although the second embodiment was described using an example with two printing operations, the number of printing operations can be more than two. When the number of printing operations is n, the stereolithography printing apparatus 100A can, for example, alternately execute the first and second printing operations, such that the odd-numbered printing operations not exceeding n are performed as the first printing operation, and the even-numbered printing operations not exceeding n are performed as the second printing operation. Furthermore, the alternation of the first and second printing operations is not limited; for example, a second printing operation may be performed after multiple first printing operations, followed by multiple more first printing operations.

[0179] 3. Variations

[0180] The methods illustrated above can be modified in a variety of ways. Specific modifications are illustrated below. Two or more methods chosen from the following examples can be appropriately combined without contradiction.

[0181] 3-1. First Variation Example

[0182] Although the head 310 moves away from the base 210 in the first embodiment, it is not limited to this. The head 310 can also move towards the base 210, as long as it avoids the state of the arm 220 being fully extended or close to it at the start of the printing operation. That is, as explained in the first embodiment, from the viewpoint of suppressing vibration of the arm 220, it is preferable to avoid a state where the first angle θ1 at the start of the printing operation is greater than 140 degrees. Furthermore, it is even more preferable to avoid a state where the first angle θ1 is greater than 140 degrees during the execution of the printing operation.

[0183] In the first variation, the first angle θ1 at the point when the ink begins to be ejected from the head 310 during the printing operation, i.e., the start time of the printing operation, is 140 degrees or less. Furthermore, it is preferable that the first angle θ1 at the start of an acceleration action included in a non-printing operation to be performed before the printing operation is 140 degrees or less. 1S Below 140 degrees Celsius.

[0184] Furthermore, it is preferable that the first angle θ1 at the start time of the printing operation is 120 degrees or less. Furthermore, it is preferable that the first angle θ1 at the start time of the printing operation is 100 degrees or less.

[0185] In the printing operation of the first modified example, the head 310 can move away from the base 210 or move towards the base 210.

[0186] The first modified stereolithography printing apparatus 100 includes: a head 310 that sprays ink onto a three-dimensional workpiece W; and a robot 200 that changes the relative position of the workpiece W and the head 310. The robot 200 includes an arm 220 and a base 210 connected to one end of the arm 220. The arm 220 has an arm component 226 and a plurality of joints 230, the arm component 226 being the other end of the arm 220 and a tip portion supporting the head 310. The first modified stereolithography printing apparatus 100 performs a printing action in which the robot 200 moves the position of the head 310 while ink is sprayed from the head 310. The plurality of joints 230 includes joints 230_3, 230_2, and 230_5. Joint 230_2 is closer to the base 210 than joint 230_3, and joint 230_5 is closer to the arm component 226 than joint 230_3. Joint 230_3 rotates around rotation axis O3, joint 230_2 rotates around rotation axis O2, and joint 230_5 rotates around rotation axis O5. The robot 200 can make rotation axes O3, O2, and O5 parallel to each other. When the line segment connecting joints 230_2 and 230_3 is designated as the first imaginary line segment L1, the line segment connecting joints 230_3 and 230_5 is designated as the second imaginary line segment L2, and the angle formed by the first imaginary line segment L1 and the second imaginary line segment L2 is designated as the first angle θ1, the first angle θ1 at the time when the head 310 begins to spray ink during the printing action is less than 140 degrees.

[0187] like Figure 11 As shown, the tilt of the first angle characteristic Cθ1 when the first angle θ1 is between 140 degrees and 180 degrees is greater than the tilt of the first angle characteristic Cθ1 when the first angle θ1 is between 0 degrees and 140 degrees. Therefore, according to the first modified example, compared with the case where the first angle θ1 at the start time of the printing operation is greater than 140 degrees, the vibration generated in the joint 230_3 can be reduced, thereby improving the printing quality.

[0188] In the first variation, similar to the first embodiment, the rotation of joint 230_3 during the execution of the printing action is greater than the rotation of joint 230_2.

[0189] Therefore, joint 230_3 is more prone to vibration than joint 230_2 during the printing process. Therefore, if the head 310 is moved such that the first angle θ1 at the start of the printing action is less than 140 degrees, thereby suppressing the vibration of joint 230_3 during the printing action, the printing quality can be effectively improved.

[0190] Furthermore, preferably, during the printing operation, the first angle θ1 at the point where ink ejection begins at the head 310 is 120 degrees or less. For example... Figure 11As shown, since the first angle θ1 at the start time of the printing action is less than 120 degrees compared to the first angle θ1 at the start time of the first printing action being greater than 120 degrees, the tilt of the first angle characteristic Cθ1 is smaller, which can reduce the vibration generated in the joint 230_3, thus improving the printing quality.

[0191] Furthermore, preferably, during the printing operation, the first angle θ1 at the point when the head 310 begins to eject ink is 100 degrees or less. For example... Figure 11 As shown, the vibration generated in joint 230_3 can be reduced when the first angle θ1 at the start time of the printing action is less than 100 degrees compared to the method where the first angle θ1 at the start time of the first printing action is greater than 100 degrees, thereby improving the printing quality.

[0192] Furthermore, similar to the first embodiment, the plurality of joints includes a joint 230_1 disposed between joint 230_3 and base 210, and joint 230_1 rotates about rotation axis O1, with rotation axis O2 and rotation axis O1 being perpendicular to each other.

[0193] 3-2. Second variation

[0194] Although the above description illustrates a structure in which three joints 230 move during the execution of the printing action, it is not limited to this and a structure in which four or more joints 230 move during the execution of the printing action is also possible. Furthermore, the rotation axes of the three joints 230 are not limited to being orthogonal to the Z-axis, but can be arbitrary.

[0195] 3-3. Third variation example

[0196] While the above description illustrates a structure using a six-axis vertical multi-axis robot as robot 200, it is not limited to this structure. Robot 200 can be, for example, a vertical multi-axis robot with axes other than six, or a horizontal multi-axis robot. Furthermore, it can also be a robot that has telescopic mechanisms in addition to rotary joints. However, from the viewpoint of balancing print quality during printing operations and the degrees of freedom of the robot's movements during non-printing operations, a multi-axis robot with six or more axes is preferred.

[0197] Furthermore, although the robot 200 of the first embodiment only has a rotary joint, the robot 200 may also have a linear joint in addition to a rotary joint.

[0198] 3-4. Fourth variation

[0199] Although the above-described method illustrates a structure using screws or similar means to fix the liquid nozzle to the top of the arm 220, it is not limited to this structure. For example, the liquid nozzle can be held by a gripping mechanism such as a handle mounted on the top of the arm 220, thereby fixing the liquid nozzle to the top of the arm 220.

[0200] 3-5. Fifth variation

[0201] Although the above-described method illustrates a structure that uses one type of ink for printing, it is not limited to that structure, and the invention can be applied even in structures that use two or more types of ink for printing.

[0202] Symbol Explanation

[0203] 100, 100A…Stereolithography printing apparatus; 200, 200A…Robot; 210…Base; 220…Arm; 221, 222, 223, 224, 225, 226…Arm components; 230…Joint; 240…Arm drive mechanism; 241…Encoder; 300…Liquid ejection unit; 310…Head; 311…Piezoelectric element; 320…Pressure regulating valve; 330…Sensor; 340…Switching circuit; 350…Support body; 400…Liquid supply unit; 410…Liquid storage Storage section; 420…supply channel; 421…upstream channel; 422…downstream channel; 422a…channel component; 500…control module; 510…timing signal generation circuit; 520…power supply circuit; 530…control circuit; 540…drive signal generation circuit; 600, 600A…controller; 610, 610A…storage circuit; 620…processing circuit; 700, 700A…computer; AX…long axis; BN…setting surface; C2…second angle; CLK…clock signal; CNG …Conversion signal; Com…Drive signal; Cθ1…First angle characteristic; Cθ2…Second angle characteristic; D1…Output signal; D2, D3…Signals; Da, DaA…Path information; F…Nozzle face; L1…First imaginary line segment; L2…Second imaginary line segment; L3…Third imaginary line segment; LAT…Latch signal; La…First nozzle array; Lb…Second nozzle array; N…Nozzle; O1, O2, O3, O4, O5, O6…Rotation axis; PD…Drive pulse; PE, PE1a, PE1 b, PE2a, PE2b… Printing end position; PS, PS1a, PS1b, PS2a, PS2b… Printing start position; PTS… Timing signal; RU, RU1, RU1a, RU1b, RU2, RU2a, RU2b… Movement path; SI, Sk… Control signal; VBS… Offset potential; VHV… Power supply potential; W… Workpiece; WF… Surface; dCom… Waveform specification signal; dm1, dm2… Distance; gc, ge1, ge2… Curve; θ1, θ1E θ 1S …first angle; θ2, θ 2E θ 2S …Second perspective.

Claims

1. A three-dimensional printing apparatus, characterized in that, have: The head sprays liquid onto a three-dimensional workpiece and has multiple nozzles for spraying liquid. A robot comprising an arm and a base connected to one end of the arm, which causes changes in the relative position of the workpiece and the head. The arm has a tip and multiple joints, the tip being the other end of the arm and supporting the head. The 3D printing apparatus performs a first printing action and a non-printing action. The first printing action is the movement of the robot's head while liquid is being ejected from the head. The non-printing action is the movement of the robot's head while liquid is not being ejected from the head. During the execution of the first printing action, the head moves away from the base. The number of the plurality of joints that move in the first printing action is less than the number of the plurality of joints that move in the non-printing action.

2. The three-dimensional printing apparatus as described in claim 1, characterized in that, The arm includes: First arm component; The second arm component is connected to the first arm component and is positioned closer to the base than the first arm component. The plurality of joints includes a first joint that connects the first arm component and the second arm component. During the execution of the first printing action, the head moves in a manner that increases the angle between the first arm component and the second arm component.

3. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, The plurality of joints includes a first joint, a second joint, and a third joint. The second joint is closer to the base than the first joint. The third joint is closer to the top end than the first joint. The first joint rotates around the first rotation axis. The second joint rotates around the second rotation axis. The third joint rotates around the third rotation axis. The robot is capable of making the first rotation axis, the second rotation axis, and the third rotation axis parallel to each other. When the line segment connecting the second joint and the first joint is set as the first imaginary line segment, the line segment connecting the first joint and the third joint is set as the second imaginary line segment, and the angle formed by the first imaginary line segment and the second imaginary line segment is set as the first angle, during the execution of the first printing action, the head moves in a manner that increases the first angle.

4. The three-dimensional printing apparatus as described in claim 3, characterized in that, In the first printing action, the rotation of the first joint is greater than the rotation of the second joint.

5. The three-dimensional printing apparatus as described in claim 3, characterized in that, The plurality of joints includes a fourth joint disposed between the second joint and the base. The fourth joint rotates around the fourth rotation axis. When the line segment connecting the second joint and the fourth joint is set as the third imaginary line segment, and the angle formed by the first imaginary line segment and the third imaginary line segment is set as the second angle, during the execution of the first printing action, the head moves in a manner that makes the second angle smaller.

6. The three-dimensional printing apparatus as described in claim 3, characterized in that, The plurality of joints includes a fourth joint disposed between the second joint and the base. The fourth joint rotates around the fourth rotation axis. The second rotation axis and the fourth rotation axis are perpendicular to each other.

7. The three-dimensional printing apparatus as described in claim 3, characterized in that, When performing multiple printing actions in which the robot moves the head while simultaneously ejecting liquid from the head, it is possible to select between a first printing mode and a second printing mode. If the first printing mode is selected, perform the first printing action multiple times, but do not perform the second printing action. When the second printing mode is selected, the first printing action is performed one or more times, and the second printing action is performed one or more times. The second printing action is the movement of the robot moving the position of the head while simultaneously ejecting liquid from the head. During the execution of the second printing action, the head moves toward the base.

8. The three-dimensional printing apparatus as described in claim 7, characterized in that, The first angle at the start of the second printing action is less than 140 degrees.

9. The three-dimensional printing apparatus as described in claim 3, characterized in that, The first angle at the start of the first printing action is less than 140 degrees.

10. A three-dimensional printing apparatus, characterized in that, have: The head sprays liquid onto a three-dimensional workpiece and has multiple nozzles for spraying liquid. A robot comprising an arm and a base connected to one end of the arm, which causes changes in the relative position of the workpiece and the head. The arm has a tip and multiple joints, the tip being the other end of the arm and supporting the head. The stereolithography printing apparatus performs a printing action in which the robot moves the position of the head while liquid is ejected from the head. The plurality of joints includes a first joint, a second joint, and a third joint. The second joint is closer to the base than the first joint. The third joint is closer to the top end than the first joint. The first joint rotates around the first rotation axis. The second joint rotates around the second rotation axis. The third joint rotates around the third rotation axis. The robot is capable of making the first rotation axis, the second rotation axis, and the third rotation axis parallel to each other. When the line segment connecting the second joint and the first joint is defined as the first imaginary line segment, the line segment connecting the first joint and the third joint is defined as the second imaginary line segment, and the angle formed by the first imaginary line segment and the second imaginary line segment is defined as the first angle, During the execution of the printing action, the head moves away from the base. The first angle at the point in time when the head begins to eject liquid during the printing action is less than 140 degrees.

11. The three-dimensional printing apparatus as claimed in claim 10, characterized in that, In the printing operation, the rotation of the first joint is greater than the rotation of the second joint.

12. The three-dimensional printing apparatus as described in claim 10 or 11, characterized in that, The first angle at the point in time when the head begins to eject liquid during the printing operation is less than 120 degrees.

13. The three-dimensional printing apparatus as claimed in claim 10, characterized in that, The first angle at the point in time when the head begins to eject liquid during the printing operation is less than 100 degrees.

14. The three-dimensional printing apparatus as claimed in claim 10, characterized in that, The plurality of joints includes a fourth joint disposed between the first joint and the base. The fourth joint rotates about the fourth rotation axis. The second rotation axis and the fourth rotation axis are perpendicular to each other.

15. A method for printing three-dimensional objects, characterized in that, The 3D printing method uses a head and a robot. The head sprays liquid onto the three-dimensional workpiece and has multiple nozzles for spraying liquid. The robot includes an arm and a base connected to one end of the arm, and allows for changes in the relative position of the workpiece and the head. The arm has a tip and multiple joints, the tip being the other end of the arm and supporting the head. In the three-dimensional printing method, a first printing action is performed in which the robot moves the position of the head while liquid is being ejected from the head, and a non-printing action is performed in which the robot moves the position of the head while the head is not ejecting liquid. During the execution of the first printing action, the head moves away from the base. The number of the plurality of joints that move in the first printing action is less than the number of the plurality of joints that move in the non-printing action.

16. A method for printing three-dimensional objects, characterized in that, The 3D printing method uses a head and a robot. The head sprays liquid onto the three-dimensional workpiece and has multiple nozzles for spraying liquid. The robot includes an arm and a base connected to one end of the arm, and allows for changes in the relative position of the workpiece and the head. The arm has a tip and multiple joints, the tip being the other end of the arm and supporting the head. In the three-dimensional printing method, a printing action is performed in which the robot moves the position of the head while liquid is being ejected from the head. The plurality of joints includes a first joint, a second joint, and a third joint. The second joint is closer to the base than the first joint. The third joint is closer to the top end than the first joint. The first joint rotates around the first rotation axis. The second joint rotates around the second rotation axis. The third joint rotates around the third rotation axis. The robot is capable of making the first rotation axis, the second rotation axis, and the third rotation axis parallel to each other. When the line segment connecting the second joint and the first joint is defined as the first imaginary line segment, the line segment connecting the first joint and the third joint is defined as the second imaginary line segment, and the angle formed by the first imaginary line segment and the second imaginary line segment is defined as the first angle, During the execution of the printing action, the head moves away from the base. The first angle at the point in time when the head begins to eject liquid during the printing action is less than 140 degrees.

Images