Stereoscopic object printing apparatus and stereoscopic object printing method

Abstract

The present application provides a kind of three-dimensional object printing device and three-dimensional object printing method for improving the quality of printing.The three-dimensional object printing device has: liquid ejection head, which sprays liquid to three-dimensional workpiece;Moving mechanism, which changes the relative position of liquid ejection head relative to workpiece, moving mechanism has N (wherein, N is 2 or more natural number) joints capable of rotating around different rotating shafts, in the case of executing printing action of moving mechanism relative to the workpiece to change the relative position of liquid ejection head and liquid ejection head sprays liquid, the number of joints in N that rotate during the execution of printing action is M (wherein, M is a natural number less than N).

Description

TECHNICAL FIELD

[0001] The present application relates to a three-dimensional object printing apparatus and a three-dimensional object printing method. BACKGROUND

[0002] A three-dimensional object printing apparatus that performs printing on a surface of a three-dimensional workpiece by an inkjet method is known. For example, a system described in Patent Literature 1 has a multi-axis robot configured of a plurality of movable joint members, and a printing head disposed on the robot, and causes ink droplets to be ejected from the printing head toward a curved surface of a vehicle.

[0003] The apparatus described in Patent Literature 1 causes all of the plurality of movable joint members possessed by the robot to act during printing. Therefore, in the apparatus described in Patent Literature 1, the deviation of the actual movement path of the printing head from the ideal movement path becomes large due to the overlapping of the action errors of the respective movable joint members, and as a result, there is a problem that the reduction in printing quality is caused.

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2015-520011 SUMMARY

[0005] In order to solve the above problems, one embodiment of the three-dimensional object printing apparatus according to the present application has a liquid ejection head that ejects a liquid toward a three-dimensional workpiece, and a movement mechanism that changes the relative position of the liquid ejection head with respect to the workpiece, the movement mechanism having N (where N is a natural number of 2 or more) joints that are able to rotate around mutually different rotation axes, and in the case where the movement mechanism changes the relative position of the liquid ejection head with respect to the workpiece and the liquid ejection head ejects a liquid in a printing operation, the number of joints among the N joints that rotate during the execution of the printing operation is M (where M is a natural number smaller than N).

[0006] Another aspect of the present application relates to a three-dimensional object printing apparatus including: a liquid discharge head that discharges a liquid onto a three-dimensional workpiece; a movement mechanism that changes a relative position of the liquid discharge head with respect to the workpiece, the three-dimensional object printing apparatus performing: a printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head discharges the liquid; and a non-printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head does not discharge the liquid, wherein the movement mechanism includes a plurality of joints that are capable of rotating about different axes of rotation, the plurality of joints including: a first joint that rotates during each of the printing operation and the non-printing operation; and a second joint that does not rotate during the printing operation and rotates during the non-printing operation.

[0007] Another aspect of the present application relates to a three-dimensional object printing method that uses a liquid discharge head and a movement mechanism to print a three-dimensional workpiece, the liquid discharge head discharging a liquid onto the workpiece, the movement mechanism changing a relative position of the liquid discharge head with respect to the workpiece, the three-dimensional object printing method performing: a printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head discharges the liquid; and a non-printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head does not discharge the liquid, wherein the movement mechanism includes N joints that are capable of rotating about different axes of rotation, N being a natural number of two or more, and wherein, in the printing operation, a number of the N joints that rotate during the printing operation is M, M being a natural number that is less than N.

[0008] Another aspect of the present application relates to a three-dimensional object printing method that uses a liquid discharge head and a movement mechanism to print a three-dimensional workpiece, the liquid discharge head discharging a liquid onto the workpiece, the movement mechanism changing a relative position of the liquid discharge head with respect to the workpiece, the three-dimensional object printing method performing: a printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head discharges the liquid; and a non-printing operation in which the movement mechanism changes the relative position of the liquid discharge head with respect to the workpiece and the liquid discharge head does not discharge the liquid, wherein the movement mechanism includes a plurality of joints that are capable of rotating about different axes of rotation, the plurality of joints including: a first joint that rotates during each of the printing operation and the non-printing operation; and a second joint that does not rotate during the printing operation and rotates during the non-printing operation. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0011] Figure 3 A perspective view for showing an outline structure of a liquid ejection unit in the first embodiment.

[0012] Figure 4 A flowchart for showing a flow of a three-dimensional object printing method according to the first embodiment.

[0013] Figure 5 A view for explaining a movement path of the liquid ejection head with respect to the workpiece in the first embodiment.

[0014] Figure 6 A schematic view for explaining a printing operation.

[0015] Figure 7 A view for showing changes in amounts of operations of respective joints with respect to time elapse in a case where the number of joints driven during execution of the printing operation is six.

[0016] Figure 8 A view for showing changes in amounts of operations of respective joints with respect to time elapse in a case where the number of joints driven during execution of the printing operation is three.

[0017] Figure 9 A graph for showing a relationship between a position in a scanning direction of the liquid ejection head and an amount of deviation from an ideal path.

[0018] Figure 10 A top view for showing an outline of a three-dimensional object printing apparatus according to the second embodiment.

[0019] Figure 11 A block diagram for showing an electrical structure of the three-dimensional object printing apparatus according to the second embodiment.

[0020] Figure 12 A flowchart for showing a flow of a three-dimensional object printing method according to the second embodiment.

[0021] Figure 13 A schematic view for explaining a first printing operation and a second printing operation. DETAILED DESCRIPTION

[0022] Hereinafter, preferred embodiments to which the present application pertains will be described with reference to the accompanying drawings. Also, in each drawing, the size or scale of each part is appropriately different from the actual situation, and also parts that are shown schematically for easy understanding are included. Furthermore, in the following description, the scope of the present application is not limited to these modes as long as there is no description that particularly limits the present application.

[0023] The following description is appropriately made using an X axis, a Y axis, and a Z axis that intersect with each other. Also, one direction along the X axis is referred to as an X1 direction, and a direction opposite to the X1 direction is referred to as an X2 direction. Similarly, directions opposite to each other along the Y axis are referred to as a Y1 direction and a Y2 direction. Also, directions opposite to each other along the Z axis are referred to as a Z1 direction and a Z2 direction.

[0024] Here, the X axis, the Y axis, and the Z axis are coordinate axes of a reference coordinate system that is set within a space in which a workpiece W and a base 210 described later are disposed. Typically, the Z axis is an axis that is vertical, and the Z2 direction corresponds to a lower direction in the vertical direction. Also, the Z axis can not be an axis that is vertical. Furthermore, although the X axis, the Y axis, and the Z axis are typically orthogonal to each other, they are not limited thereto, and there are cases in which they are not orthogonal. For example, the X axis, the Y axis, and the Z axis only need to intersect with each other at an angle within a range of 80° or more and 100° or less.

[0025] 1. First Embodiment

[0026] 1-1. Outline of Stereoscopic Object Printing Device

[0027] Figure 1 is a stereogram that shows an outline of a stereoscopic object printing device 100 to which the first embodiment pertains. The stereoscopic object printing device 100 is a device that performs printing on a surface of a stereoscopic workpiece W by an inkjet method.

[0028] The workpiece W has a face WF that is a printing target. In the example shown in Figure 1 , the workpiece W is a rugby ball that is a long spherical shape around a long axis AX, and the face WF is a curved surface whose curvature is not constant. In the present embodiment, the workpiece W is disposed in a manner in which the long axis AX is parallel to the X axis. Also, the workpiece W is not limited to a rugby ball. Here, the manner of the shape or size or the like of the workpiece W is not limited to the example shown in Figure 1 , but is an arbitrary manner. For example, the surface of the workpiece W can have a flat surface, a stepped surface, or a concave-convex surface, or the like. Also, the disposition posture of the workpiece W is not limited to the example shown in Figure 1 , but is an arbitrary posture.

[0029] In the example shown in Figure 1In 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 discuss... Figure 1 Each part of the three-dimensional printing apparatus 100 shown will be briefly described in turn.

[0030] Robot 200 is a moving mechanism that changes the position and orientation of liquid ejection unit 300 relative to workpiece W. Figure 1 In the example shown, robot 200 is a so-called six-axis vertical joint robot. Specifically, robot 200 has a base 210 and an arm 220.

[0031] The base 210 is a platform that supports the arm 220. Figure 1 In the example shown, the base 210 is fixed to a mounting surface such as a floor surface facing the Z1 direction by means of screws or the like. Furthermore, the mounting surface of the base 210 can be a surface facing any direction, and is not limited to any particular direction. Figure 1 The examples shown could also be surfaces such as walls, ceilings, or movable flatbed trucks.

[0032] Arm 220 is a six-axis robotic arm having a base end mounted on a base 210 and a tip end that allows the position and orientation to change three-dimensionally relative to the base end. Specifically, arm 220 has arms 221, 222, 223, 224, 225, and 226, which are connected in this order.

[0033] Arm 221 is connected to base 210 via joint 230_1 so as to be rotatable about rotation axis O1. Arm 222 is connected to arm 221 via joint 230_2 so as to be rotatable about rotation axis O2. Arm 223 is connected to arm 222 via joint 230_3 so as to be rotatable about rotation axis O3. Arm 224 is connected to arm 223 via joint 230_4 so as to be rotatable about rotation axis O4. Arm 225 is connected to arm 224 via joint 230_5 so as to be rotatable about rotation axis O5. Arm 226 is connected to arm 225 via joint 230_6 so as to be rotatable about rotation axis O6. In the following text, joints 230_1 to 230_6 may sometimes be referred to as joint 230.

[0034] Here, joints 230_1 to 230_6 are examples of a "joint". Figure 1In the illustrated example, the number N of the joint sections 230 is six. In addition, the joint section 230_1 is an example of a "second joint", and the rotation axis O1 is an example of a "second rotation axis". The joint section 230_2 is an example of a "first joint", and the rotation axis O2 is an example of a "first rotation axis". The joint section 230_3 is an example of a "fourth joint", and the rotation axis O3 is an example of a "fourth rotation axis". The joint section 230_5 is an example of a "third joint", and the rotation axis O5 is an example of a "third rotation axis".

[0035] The joint sections 230_1 to 230_6 are each a mechanism that links one of two adjacent arms to the other in a rotatable manner. Although not illustrated in FIG. 2, a drive mechanism that rotates one of two adjacent arms with respect to the other is provided on each of the joint sections 230_1 to 230_6. Figure 1 The drive mechanism has, for example, a motor that generates a driving force for the rotation, a speed reducer that reduces and outputs the driving force, and an encoder such as a rotary encoder that detects an angle or the like of the rotation. In addition, the collection of the drive mechanisms corresponds to the arm drive mechanism 240 described later. Furthermore, the encoder corresponds to the encoder 241 described later. Figure 2 The illustrated arm drive mechanism 240. In addition, the encoder corresponds to the encoder 241 described later. Figure 2

[0036] The rotation axis O1 is an axis that is perpendicular with respect to a non-illustrated arrangement surface of the fixed base 210. The rotation axis O2 is an axis that is perpendicular with respect to the rotation axis O1. The rotation axis O3 is an axis that is parallel with respect to the rotation axis O2. The rotation axis O4 is an axis that is perpendicular with respect to the rotation axis O3. The rotation axis O5 is an axis that is perpendicular with respect to the rotation axis O4. The rotation axis O6 is an axis that is perpendicular with respect to the rotation axis O5.

[0037] In addition, for these rotation axes, "perpendicular" includes a case where an angle formed by two rotation axes deviates from 90° by about ±5°, in addition to a case where the angle is strictly 90°. Likewise, "parallel" includes a case where one of two rotation axes is inclined with respect to the other by about ±5°, in addition to a case where the two rotation axes are strictly parallel.

[0038] On the top end of the above arm 220, i.e., the arm 226, a liquid ejection unit 300 is installed as an end effector.

[0039] ​The liquid ejection unit 300 is a device having a liquid ejection head 310 that ejects ink as an example of a liquid toward the workpiece W. In the present embodiment, the liquid ejection unit 300 has, in addition to the liquid ejection head 310, a pressure regulating valve 320 that regulates the pressure of the ink supplied to the liquid ejection head 310, and a sensor 330 that measures the distance between the liquid ejection head 310 and the workpiece W. Since they are fixed together on the arm 226, the positional and attitudinal relationship with each other is fixed.

[0040] The ink is not particularly limited, and examples thereof include an aqueous ink in which a color material such as a dye or a pigment is dissolved in a water-based solvent, a curable ink in which a curable resin such as an ultraviolet-curable resin is used, and a solvent-based ink in which a color material such as a dye or a pigment is dissolved in an organic solvent. In addition, the ink is not limited to a solution, and can also be an ink in which a color material or the like is dispersed as a dispersed substance in a dispersant. Furthermore, the ink is not limited to an ink containing a color material, and can also be an ink containing conductive particles such as metal particles as a dispersed substance for forming a wiring or the like.

[0041] Although not illustrated in Figure 1 , the liquid ejection head 310 has a piezoelectric element, a cavity that accommodates the ink, and a nozzle that communicates with the cavity. Here, the piezoelectric element is provided for each cavity, and the ink is ejected from the nozzle corresponding to the cavity by changing the pressure of the cavity. Such a liquid ejection head 310 is obtained, for example, by adhering a plurality of substrates of a silicon substrate or the like that has been appropriately processed by etching or the like with an adhesive or the like. In addition, the piezoelectric element corresponds to the piezoelectric element 311 illustrated in Figure 2 later. Furthermore, as a driving element for ejecting the ink from the nozzle, a heater that heats the ink in the cavity can also be used instead of the piezoelectric element.

[0042] The pressure regulating valve 320 is a valve mechanism that opens and closes in accordance with the pressure of the ink in the liquid ejection head 310. By this opening and closing, the pressure of the ink in the liquid ejection head 310 is maintained as a negative pressure within a predetermined range. Thus, stabilization of the meniscus of the ink formed in the nozzle N of the liquid ejection head 310 is achieved. As a result, the entry of air bubbles into the nozzle N or the overflow of the ink from the nozzle N is prevented.

[0043] The sensor 330 is an optical displacement sensor that measures the distance between the liquid ejection head 310 and the workpiece W. In addition, the sensor 330 need only be provided as necessary, and can be omitted. Furthermore, although not illustrated in Figure 1In the example shown, the liquid ejection unit 300 has one liquid ejection head 310 and one pressure regulating valve 320, but this number is not limited to one. Figure 1 The example shown can be two or more. Furthermore, the position of the pressure regulating valve 320 is not limited to arm 226; for example, it can be other arms, or it can be fixed relative to the base 210.

[0044] The liquid supply unit 400 is a mechanism for supplying ink to the liquid nozzle 310. The liquid supply unit 400 has a liquid reservoir 410 and a supply channel 420.

[0045] The liquid storage section 410 is a container for storing ink. The liquid storage section 410 is, for example, a bag-shaped ink packet formed of a flexible film.

[0046] exist Figure 1 In the example shown, the liquid reservoir 410 is fixed to a wall, ceiling, or column in a manner that always positions it in the Z1 direction relative to the liquid nozzle 310. That is, the liquid reservoir 410 is located above the moving area of ​​the liquid nozzle 310 in the vertical direction. Therefore, even without using a pump or similar mechanism, ink can be supplied from the liquid reservoir 410 to the liquid nozzle 310 at a predetermined pressure.

[0047] Furthermore, the liquid reservoir 410 can be positioned such that ink can be supplied from the liquid reservoir 410 to the liquid nozzle 310 at a predetermined pressure, or it can be located slightly below the liquid nozzle 310 in the vertical direction. In this case, for example, a pump can be used to supply ink from the liquid reservoir 410 to the liquid nozzle 310 at a predetermined pressure.

[0048] The supply channel 420 is a channel for supplying ink from the liquid reservoir 410 to the liquid nozzle 310. A pressure regulating valve 320 is provided midway through the supply channel 420. Therefore, even if the positional relationship between the liquid nozzle 310 and the liquid reservoir 410 changes, the pressure fluctuation of the ink in the liquid nozzle 310 can be reduced.

[0049] 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 or an elastomer, and is flexible. Thus, by using a flexible tube to construct the supply channel 420, changes in the relative positional relationship between the liquid reservoir 410 and the pressure regulating valve 320 are permitted. Therefore, even if the position or orientation of the liquid nozzle 310 changes while maintaining a fixed position and orientation of the liquid reservoir 410, ink can still be supplied from the liquid reservoir 410 to the pressure regulating valve 320.

[0050] In addition, a part of the supply flow path 420 can also be configured by a member that does not have flexibility. Furthermore, a part of the supply flow path 420 can be configured as a structure having a distribution flow path that distributes ink to a plurality of sites, or can be configured in an integrated manner with the liquid ejection head 310 or the pressure regulating valve 320.

[0051] The controller 600 is a robot controller that controls driving of the robot 200. Although not illustrated in Figure 1 , a control module that controls ejection operation in the liquid ejection unit 300 is electrically connected to the controller 600. A computer is communicably connected to the controller 600 and the control module. In addition, the control module corresponds to the control module 500 described later. Figure 2 Figure 2

[0052] 1-2. Electrical structure of the stereoscopic object printing apparatus

[0053] Figure 2 A block diagram showing an electrical structure of the stereoscopic object printing apparatus 100 according to the first embodiment. In Figure 2 , electrical structure elements among the structure elements of the stereoscopic object printing apparatus 100 are shown. Furthermore, in Figure 2 , the arm driving mechanism 240 including the encoders 241_1 to 241_6 is shown. The arm driving mechanism 240 is a collection of the driving mechanisms described above that actuate the joint sections 230_1 to 230_6. The encoders 241_1 to 241_6 are provided corresponding to the joint sections 230_1 to 230_6 to measure the amounts of operation such as the rotation angles of the encoders 241_1 to 241_6. In addition, hereinafter, each of the encoders 241_1 to 241_6 will be sometimes referred to as the encoder 241.

[0054] As shown in Figure 2 ​​As shown, the stereoscopic object printing apparatus 100 has a control module 500 and a computer 700 in addition to the robot 200, the liquid ejection unit 300, and the controller 600 described above. In addition, each of the structures described below can be appropriately divided, can have a part thereof included in another structure, and can be configured in an integrated manner with another structure. For example, a part or all of the functions of the control module 500 or the controller 600 can be realized by the computer 700 connected to the controller 600, or can be realized by another external device such as a PC (personal computer) connected to the controller 600 via a network such as a LAN (Local Area Network) or the Internet.

[0055] The controller 600 has a function of controlling the driving of the robot 200 and a function of generating a signal D3 for synchronizing the ejection operation of the liquid ejection head 310 with the operation of the robot 200. The controller 600 has a storage circuit 610 and a processing circuit 620.

[0056] The storage circuit 610 stores various programs executed by the processing circuit 620 and various data processed by the processing circuit 620. The storage circuit 610 includes, for example, one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). In addition, a part or all of the storage circuit 610 can be included in the processing circuit 620.

[0057] The path information Da is stored in the storage circuit 610. The path information Da is information indicating a path through which the liquid ejection head 310 should move. Specifically, the path information Da includes information indicating a path through which a tool center point should move, the tool center point indicating an origin of a tool coordinate system described below. The path information Da is indicated using coordinate values of a reference coordinate system, for example. The path information Da is determined based on workpiece information indicating a position and a shape of the workpiece W. The workpiece information is obtained by associating information such as CAD (computer-aided design) data indicating a three-dimensional shape of the workpiece W with the reference coordinate system described above. The path information Da described above is input from the computer 700 to the storage circuit 610.

[0058] The processing circuit 620 controls the operation of the joint sections 230_1 to 230_6 on the basis of the path information Da and generates a signal D3. Specifically, the processing circuit 620 performs an operation of converting the path information Da into an operation amount such as a rotation angle and a rotation speed of each of the joint sections 230_1 to 230_6, that is, inverse kinematics calculation. Further, the processing circuit 620 outputs control signals Sk_1 to Sk_6 on the basis of outputs D1_1 to D1_6 from encoders 241_1 to 241_6 included in the arm drive mechanism 240 of the robot 200 so that an actual rotation angle and an operation amount such as a rotation speed of each of the joint sections 230_1 to 230_6 become the operation result of the above operation. The control signals Sk_1 to Sk_6 correspond to the joint sections 230_1 to 230_6 and control driving of a motor provided on the corresponding joint section 230. In addition, the outputs D1_1 to D1_6 correspond to the encoders 241_1 to 241_6. Hereinafter, each of the outputs D1_1 to D1_6 will be sometimes referred to as an output D1.

[0059] Further, the processing circuit 620 generates the signal D3 on the basis of an output D1 from at least one of the encoders 241_1 to 241_6. For example, the processing circuit 620 generates a trigger signal including a pulse at a timing at which the output D1 from one of the encoders 241_1 to 241_6 becomes a predetermined value as the signal D3.

[0060] The processing circuit 620 described above includes one or more processors such as CPUs (Central Processing Units). In addition, the processing circuit 620 can include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU.

[0061] The control module 500 is a circuit that controls the ejection operation of the liquid ejection head 310 on the basis of the signal D3 output from the controller 600 and print data from the computer 700. The control module 500 has a timing signal generation circuit 510, a power supply circuit 520, a control circuit 530, and a drive signal generation circuit 540.

[0062] The timing signal generation circuit 510 generates a timing signal PTS on the basis of the signal D3. The timing signal generation circuit 510 is constituted by, for example, a timer that starts the generation of the timing signal PTS as an opportunity of detection of the signal D3.

[0063] The power supply circuit 520 receives supply of electric power from a commercial power supply not shown, and generates predetermined various electric potentials. The generated various electric potentials are supplied to each portion of the three-dimensional object printing apparatus 100 as appropriate. The power supply circuit 520 generates, for example, a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejection unit 300. Further, the power supply potential VHV is supplied to the drive signal generation circuit 540.

[0064] The control circuit 530 generates a control signal SI, a waveform designation signal dCom, a latch signal LAT, a clock signal CLK, and a switching signal CNG on the basis of the timing signal PTS. These signals are synchronized with the timing signal PTS. The waveform designation signal dCom among these signals is input to the drive signal generation circuit 540, and the other signals are input to the switching circuit 340 of the liquid ejection unit 300.

[0065] The control signal SI is a digital signal for designating an operation state of the piezoelectric element 311 possessed by the liquid ejection head 310. Specifically, the control signal SI designates whether or not to supply the drive signal Com described later to the piezoelectric element 311. By this designation, for example, it is designated whether or not to eject ink from the nozzle corresponding to the piezoelectric element 311, or the amount of ink ejected from the nozzle is designated. The waveform designation signal dCom is a digital signal for specifying the waveform of the drive signal Com. The latch signal LAT and the switching signal CNG specify the drive timing of the piezoelectric element 311, and thereby specify the ejection timing of ink from the nozzle, by being used in conjunction with the control signal SI. The clock signal CLK is a clock signal that becomes a reference synchronized with the timing signal PTS. As for the signals among the above signals that are input to the switching circuit 340 of the liquid ejection unit 300, detailed description will be given later.

[0066] The above control circuit 530 includes, for example, one or more processors such as CPUs (Central Processing Units). Alternatively, the control circuit 530 can include a programmable logic device such as an FPGA (Field-Programmable Gate Array) in place of or in addition to the CPU.

[0067] The drive signal generation circuit 540 is a circuit that generates a drive signal Com for driving each piezoelectric element 311 possessed by the liquid ejection head 310. Specifically, the drive signal generation circuit 540 has, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 540, the waveform designation signal dCom from the control circuit 530 is converted from a digital signal to an analog signal by the DA conversion circuit, and the analog signal is amplified using the power supply potential VHV from the power supply circuit 520 by the amplification circuit, thereby generating the drive signal Com. Here, the signal of the waveform included in the drive signal Com, which is actually supplied to the piezoelectric element 311, is a drive pulse PD. The drive pulse PD is supplied from the drive signal generation circuit 540 to the piezoelectric element 311 via the switching circuit 340. The switching circuit 340 switches whether to supply at least a part of the waveform included in the drive signal Com as the drive pulse PD based on the control signal SI.

[0068] The computer 700 has a function of supplying the path information Da and the like to the controller 600, and a function of supplying the print data and the like to the control module 500. Further, the computer 700 of the present embodiment is electrically connected to the sensor 330 described above, and supplies information for correcting the path information Da to the controller 600 based on the signal D2 from the sensor 330.

[0069] 1-3. Liquid ejection unit

[0070] Figure 3 A perspective view showing the outline structure of the liquid ejection unit 300 in the first embodiment.

[0071] The following description is appropriately made using the a-axis, the b-axis, and the c-axis that cross each other. Further, one direction along the a-axis is referred to as an al direction, and a direction opposite to the al direction is referred to as an a2 direction. Similarly, directions opposite to each other along the b-axis are referred to as a bl direction and a b2 direction. Further, directions opposite to each other along the c-axis are referred to as a cl direction and a c2 direction.

[0072] Here, the a-axis, the b-axis, and the c-axis are coordinate axes of a tool coordinate system set in the liquid ejection unit 300, and the relative position and the attitude thereof to the X-axis, the Y-axis, and the Z-axis described above change according to the movement of the robot 200 described above. In the present embodiment, the a-axis, the b-axis, and the c-axis are set so as to be parallel to the X-axis, the Y-axis, and the Z-axis, respectively. Figure 3 In the example shown, the c-axis is an axis parallel to the sixth rotation axis O6 described above. In addition, although the a-axis, the b-axis, and the c-axis are typically orthogonal to each other, they are not limited thereto, and for example, it is only necessary to cross at an angle in a range of 80° or more and 100° or less.

[0073] As described above, the liquid ejection unit 300 has the liquid ejection head 310, the pressure regulating valve 320, and the sensor 330. They are supported by the support body 350 shown by a double-dotted line in Figure 3 .

[0074] The support body 350 is composed of, for example, a metal material or the like, and is a substantially rigid body. In addition, although the support body 350 is in a flat box shape in Figure 3 , the shape of the support body 350 is not particularly limited and is an arbitrary shape.

[0075] The above support body 350 is mounted on the tip end of the arm 220 described above, that is, the arm 226. Therefore, the liquid ejection head 310, the pressure regulating valve 320, and the sensor 330 are fixed to the arm 226, respectively.

[0076] In the example shown in Figure 3 , the pressure regulating valve 320 is located in the cl direction with respect to the liquid ejection head 310. The sensor 330 is located in the a2 direction with respect to the liquid ejection head 310.

[0077] The supply flow path 420 is divided into an upstream flow path 421 and a downstream flow path 422 by the pressure regulating valve 320. That is, the supply flow path 420 has the upstream flow path 421 that communicates the liquid reservoir 410 with the pressure regulating valve 320, and the downstream flow path 422 that communicates the pressure regulating valve 320 with the liquid ejection head 310. In the example shown in Figure 3 , a part of the downstream flow path 422 of the supply flow path 420 is composed of a flow path member 422a. The flow path member 422a has flow paths that distribute the ink from the pressure regulating valve 320 to a plurality of sites of the liquid ejection head 310. The flow path member 422a is, for example, a laminate of a plurality of substrates composed of a resin material, and a groove or a hole for a flow path of the ink is appropriately provided on each substrate.

[0078] The liquid ejection head 310 has a nozzle face F, and a plurality of nozzles N that are opened on the nozzle face F. In the example shown in Figure 3 , the normal direction of the nozzle face F is the c2 direction, and the plurality of nozzles N are divided into a first nozzle row La and a second nozzle row Lb that are arranged at mutually spaced intervals in the direction along the a axis. The first nozzle row La and the second nozzle row Lb are each a collection of a plurality of nozzles N that are arranged in a linear shape in the direction along the b axis. Here, elements associated with each nozzle N of the first nozzle row La and elements associated with each nozzle N of the second nozzle row Lb in the liquid ejection head 310 are structures that are substantially symmetrical to each other in the direction along the a axis.

[0079] However, the positions of the plurality of nozzles N in the first nozzle row La and the plurality of nozzles N in the second nozzle row Lb in the direction along the b-axis can be identical to each other or can be different from each other. Further, elements associated with each nozzle N of one of the first nozzle row La and the second nozzle row Lb can be omitted. Hereinafter, a structure in which the positions of the plurality of nozzles N in the first nozzle row La and the plurality of nozzles N in the second nozzle row Lb in the direction along the b-axis are identical to each other will be exemplified.

[0080] 1-4. Action of the stereoscopic object printing apparatus and stereoscopic object printing method

[0081] Figure 4 A flowchart showing a flow of a stereoscopic object printing method according to the first embodiment will be described. The stereoscopic object printing method is performed using the stereoscopic object printing apparatus 100 described above. As shown in FIG. 1, the stereoscopic object printing apparatus 100 sequentially executes a step S110 of implementing a non-printing action, a step S120 of implementing a printing action, and a step S130 of implementing a non-printing action. Figure 4

[0082] The non-printing action of the step S110 is an action in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W before the printing action. In this non-printing action, the liquid discharge head 310 does not discharge ink. This non-printing action includes, for example, a preparation action in which the robot 200 moves the liquid discharge head 310 to a printing start position and brings the rotation shafts O2, O3, and O5 into a state in which they are parallel to each other. In this non-printing action, all of the six joint sections 230 possessed by the robot 200 can be caused to act, and thus the movement of the liquid discharge head 310 is implemented by the action of a larger number of joint sections 230 than in the printing action.

[0083] The printing action of the step S120 is an action in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W and the liquid discharge head 310 discharges ink. In this printing action, the movement of the liquid discharge head 310 is implemented by the action of a smaller number of joint sections 230 than in the non-printing action. Therefore, compared with the non-printing action, the deviation of the actual movement path of the liquid discharge head 310 from the ideal path is reduced. In this printing action of the present embodiment, the movement of the liquid discharge head 310 is implemented by the action of three joint sections 230 out of the six joint sections 230 possessed by the robot 200. The printing action will be described in detail hereinafter.

[0084] ​The non-printing operation of step S130 is an operation in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the work W after the printing operation. In this non-printing operation, the liquid discharge head 310 does not discharge ink. This non-printing operation includes, for example, an operation in which the robot 200 moves the liquid discharge head 310 from the printing end position to another position, and the like. In this non-printing operation, it is possible to cause all of the six joint sections 230 possessed by the robot 200 to operate, and thereby to implement the movement of the liquid discharge head 310 by the operation of a larger number of joint sections 230 than in the printing operation.

[0085] Figure 5 A diagram for explaining the movement path RU of the liquid discharge head 310 with respect to the work W in the first embodiment. In Figure 5 , a case in which printing is performed with respect to the face WF of the work W configured in such a manner that the long axis AX is made parallel to the X axis is exemplified. Here, the work W is placed at a position in the X2 direction with respect to the robot 200.

[0086] As shown in Figure 5 , in the printing operation, the robot 200 moves the liquid discharge head 310 along the movement path RU. The movement path RU is a path along the face WF from the position PS to the position PE. The movement path RU is linear when viewed in the Z2 direction, extending along the X axis.

[0087] In the printing operation, the robot 200 operates three of the six joint sections 230. In Figure 5 the example shown in , the robot 200 makes the respective rotation axes of the joint section 230 2, the joint section 230 3, and the joint section 230 5 be in a state in which they are parallel to the Y axis during the execution of the printing operation, and operates these joint sections. In this way, it is possible to move the liquid discharge head 310 along the movement path RU by the operation of three joint sections 230.

[0088] During the execution of the printing operation, the robot 200 operates three of the six joint sections 230 in such a manner that the b axis of the tool coordinate system set in the liquid discharge unit 300 and the Y axis of the reference coordinate system are kept parallel to each other. That is, during the execution of the printing operation, the robot 200 keeps the first nozzle row La and the second nozzle row Lb in a state in which they are parallel to the three joint sections 230 that are operated. In other words, during the execution of the printing operation, the robot 200 does not operate the joint sections 230_1, 230_4, and 230_6, which are joint sections whose rotation axes are not parallel to the Y axis.

[0089] In addition, although the printing operation of the present embodiment causes the rotation axes O2, O3, and O5 to be in a state of being parallel to each other, it is not limited thereto, and for example, the rotation axes O2, O3, and O6 can be caused to be in a state of being parallel to each other. In this case, the liquid discharge head 310 is caused to move along the movement path RU by the operation of the joint sections 230_2, 230_3, and 230_6. In this case, it is necessary to cause the fixed direction of the head unit 300 with respect to the arm 226 to be the same as the direction of the movement path RU. Figure 5 The example of the direction of the movement path RU differs. For example, by fixing the head unit 300 with respect to the arm 226 in a manner such that the b-axis along which the nozzle row is disposed is parallel to the rotation axis O6, it becomes possible to perform the printing operation on the work W on the movement path RU.

[0090] Figure 6 is a diagram for explaining the printing operation. In Figure 6 , the state of the liquid discharge head 310 at a portion of the movement path RU is schematically shown. Further, in Figure 6 , the liquid discharge head 310 at a predetermined timing that is earlier than the timing shown by a solid line is shown by a double-dotted line. As Figure 6 indicated, in the printing operation, the distance LI between the liquid discharge head 310 and the surface WF is maintained within a predetermined range. Further, in the printing operation, the liquid discharge head 310 opposes the surface WF in a fixed attitude. In the example shown in Figure 6 , it opposes in a manner such that the nozzle face F is parallel to the surface WF. In addition, during the execution of the printing operation, the nozzle face F can be inclined with respect to the surface WF around the Y-axis, and the inclination angle thereof can change.

[0091] Figure 7 is a graph showing the change in the operation amount of each joint section 230 with the passage of time in a case where the number of joint sections 230 driven during the execution of the printing operation is six. Figure 8 is a graph showing the change in the operation amount of each joint section 230 with the passage of time in a case where the number of joint sections 230 driven during the execution of the printing operation is three. Here, in Figure 7 and in Figure 8 , the "J1 operation amount" indicates the rotation amount of the joint section 230_1. Similarly, in Figure 7 and in Figure 8 , the "J2 to J6 operation amounts" indicate the rotation amounts of the joint sections 230_2 to 230_6.

[0092] As Figure 8In the present embodiment, as shown, the robot 200 causes the three joint sections 230, the joint section 230 2, the joint section 230 3, and the joint section 230 5, to act during execution of the printing action. On the other hand, the other three joint sections 230, the joint section 230 1, the joint section 230 4, and the joint section 230 6, do not act. In addition, Figure 7 and Figure 8 The amounts of each action shown are one example and are not limited thereto.

[0093] In addition, Figure 8 indicates the amount of rotation of the joint section 230 in the case where the workpiece W is arranged differently from Figure 5 In the same manner, the amount of rotation of the joint section 230 is arranged. On the other hand, Figure 7 indicates the amount of rotation of the joint section 230 in the case where the workpiece W is arranged differently from Figure 5 In the case where, for example, the workpiece W is arranged in such a manner that the long axis AX is parallel to the Y axis, and the movement path RU is set in such a manner that the movement path RU appears as a straight line extending along the Y axis when viewed in the Z2 direction, the joint section 230 becomes Figure 7 the amount of rotation shown.

[0094] Figure 9 is a graph showing the relationship between the position in the scanning direction of the liquid discharge head 310 and the amount of deviation from the ideal path. Figure 9 The horizontal axis "position in the scanning direction" in Figure 9 The vertical axis "amount of deviation from the ideal path" in Figure 9 The value of the vertical axis in

[0095] In the case where the three joint sections 230 are caused to act as shown in solid lines in Figure 9 compared to the case where the six joint sections 230 are caused to act as shown in dashed lines in Figure 9 the actual movement path of the liquid discharge head 310 deviates from the ideal path is reduced.

[0096] As described above, the three-dimensional object printing apparatus 100 has the liquid discharge head 310 and the robot 200 as an example of a "moving mechanism". The liquid discharge head 310 discharges ink as an example of a "liquid" with respect to the three-dimensional workpiece W. The robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W. The robot 200 has N (where N is a natural number of 2 or more) joint sections 230 as an example of a "joint" capable of rotation around mutually different rotation axes. In the present embodiment, N is 6. Thus, the robot 200 has a plurality of joint sections 230.

[0097] In a case where the three-dimensional object printing apparatus 100 changes the relative position of the liquid discharge head 310 with respect to the workpiece W by the robot 200 and the liquid discharge head 310 performs a printing operation of discharging ink, the number of joint sections 230 of the N joint sections 230 that rotate during the performance of the printing operation is M (where M is a natural number smaller than N). Thus, by setting the number of joint sections 230 that rotate during the performance of the printing operation to M, which is smaller than N, the influence of the operation error of the joint sections 230 is reduced compared to a structure in which the number of joint sections 230 that rotate during the performance of the printing operation is N, and thus it is possible to reduce the deviation of the actual movement path of the liquid discharge head 310 from the ideal movement path. As a result, it is possible to improve the printing quality.

[0098] On the other hand, in a case where the three-dimensional object printing apparatus 100 changes the relative position of the liquid discharge head 310 with respect to the workpiece W by the robot 200 and the liquid discharge head 310 performs a non-printing operation that does not discharge ink, the number of joints of the N joints that rotate during the performance of the non-printing operation is more than M and is N or less. In the present embodiment, the plurality of joint sections 230 possessed by the robot 200 include a joint section 230 2 as an example of a "first joint" that rotates during the performance of each of the printing operation and the non-printing operation, and a joint section 230 1 as an example of a "second joint" that does not rotate during the performance of the printing operation and rotates during the performance of the non-printing operation.

[0099] Thus, by setting the number of joint sections 230 that rotate during the performance of the non-printing operation to be larger than M, the degree of freedom of the operation of the robot 200 in the non-printing operation is increased compared to a structure in which the number of joint sections 230 that rotate during the performance of the non-printing operation is M. Thus, compared to a structure in which the number of joint sections 230 is M, it is possible to improve the convenience and the like in the non-printing operation.

[0100] In the present embodiment, as described above, the N number of joint sections 230 have the joint section 230 2 as an example of the "first joint", the joint section 230 1 as an example of the "second joint", and the joint section 230 5 as an example of the "third joint". The joint section 230 2 rotates around the rotation axis O2 as an example of the "first rotation axis". The joint section 230 1 rotates around the rotation axis O1 as an example of the "second rotation axis". The joint section 230 5 rotates around the rotation axis O5 as an example of the "third rotation axis".

[0101] In the three-dimensional object printing apparatus 100, during execution of the printing operation, the joint section 230 2 and the joint section 230 5 rotate respectively, and the joint section 230 1 does not rotate, and at the start timing of the printing operation, the angle formed by the rotation axis O2 and the rotation axis O5 is smaller than the angle formed by the rotation axis O2 and the rotation axis O1. In the present embodiment, the rotation axis O2 and the rotation axis O5 are parallel to each other, and the angle formed by these rotation axes is 0°. Further, in the present embodiment, the rotation axis O2 and the rotation axis O1 are orthogonal to each other, and the angle formed by these rotation axes is 90°.

[0102] As described above, the rotation axis O1 is the rotation axis of the N number of joint sections 230, which forms the largest angle with the rotation axis O2. Here, "forms the largest angle with the rotation axis O2" means closest to 90°.

[0103] Further, as described above, the rotation axis O2 and the rotation axis O5 are parallel to each other. Therefore, by causing the joint section 230 2 and the joint section 230 5 to operate, it is possible to move the liquid discharge head 310 linearly when viewed in a direction perpendicular to the rotation axis O2 or the rotation axis O5. That is, the robot 200 can move the liquid discharge head 310 in parallel with respect to an imaginary plane formed by the X axis and the Z axis.

[0104] As described above, the N number of joint sections 230 have the joint section 230 3 as an example of the "fourth joint". The joint section 230 3 rotates around the rotation axis O3 as an example of the "fourth rotation axis". In the three-dimensional object printing apparatus 100, at the start timing of the printing operation, the rotation axis O2, the rotation axis O5, and the rotation axis O3 are parallel to each other, and during execution of the printing operation, the joint section 230 2, the joint section 230 5, and the joint section 230 3 rotate respectively. Therefore, by causing the joint section 230 2, the joint section 230 5, and the joint section 230 3 to operate, it is possible to maintain the distance between the liquid discharge head 310 and the surface of the workpiece W within a desired range regardless of the shape of the workpiece W, and to move the liquid discharge head 310 linearly when viewed in a direction perpendicular to the rotation axis O2 or the rotation axis O5.

[0105] As described above, the liquid ejection head 310 has a plurality of nozzles N arranged along the b-axis as an example of "nozzle row axis". In the three-dimensional object printing apparatus 100, the rotation axis O2 and the b-axis are parallel to each other during execution of the printing operation. Therefore, by causing the joint portion 230 2 to operate around the rotation axis O2 and causing the liquid ejection head 310 to scan in a direction orthogonal to the rotation axis O2, printing over a range of the width of the plurality of nozzles N along the b-axis can be performed.

[0106] 2. Second Embodiment

[0107] Hereinafter, a second embodiment of the present application will be described. In the following described mode, the same symbols as those used in the description of the first embodiment are used for elements having the same function or action as those of the first embodiment, and detailed description thereof will be appropriately omitted.

[0108] Figure 10 A top view showing an outline of a three-dimensional object printing apparatus 100A according to the second embodiment. The three-dimensional object printing apparatus 100A is the same as the three-dimensional object printing apparatus 100 of the first embodiment described above, except that a movable portion 800 is added. The workpiece W of the present embodiment is a rectangular parallelepiped having a face WF with the Zl direction as a normal line.

[0109] The movable portion 800 is a mechanism that relatively moves the liquid ejection head 310 with respect to the workpiece W by an operation in addition to the operation of the robot 200. In the present embodiment, the movable portion 800 is a mechanism that relatively moves the liquid ejection head 310 with respect to the workpiece W by an operation in addition to the operation of the robot 200. Figure 10 In the example shown, the movable portion 800 is a linear motion mechanism that moves the workpiece W in the direction along the X-axis. Specifically, the movable portion 800 has a pair of rails 810, a table 820, and a driving mechanism 830. The pair of rails 810 are members that are arranged parallel to each other and extend in the direction along the X-axis. The table 820 is mounted on the pair of rails 810 so as to be movable in the direction along the X-axis via a linear motion bearing or the like. The driving mechanism 830 is a linear motor or the like mechanism that moves the table 820 in the direction along the X-axis with respect to the pair of rails 810. In addition, although not shown, an encoder that detects the position of the table 820 in the direction along the X-axis with respect to the pair of rails 810 is provided in the driving mechanism 830.

[0110] The movable section 800 of the above structure moves the workpiece W from a first state in which the liquid discharge head 310 opposes the first region RP1 of the face WF of the workpiece W, to a second state in which the liquid discharge head 310 opposes a second region RP2 of the face WF of the workpiece W that is different from the first region RP1. In the first state, the robot 200 is operated to move the liquid discharge head 310 along the first movement path RU_1, and the liquid discharge head 310 performs a first printing operation in which ink is discharged toward the first region RP1. In the second state, the robot 200 is operated to move the liquid discharge head 310 along the second movement path RU_2, and the liquid discharge head 310 performs a second printing operation in which ink is discharged toward the second region RP2.

[0111] Figure 11 A block diagram showing an electrical structure of the three-dimensional object printing apparatus 100A according to the second embodiment is shown in FIG. 9. As shown in FIG. 9, the movable section 800 is electrically connected to the computer 700. The computer 700 causes the workpiece W to move during a period between the first printing operation and the second printing operation. Figure 11

[0112] Figure 12 A flowchart showing a flow of a three-dimensional object printing method according to the second embodiment is shown in FIG. 10. The three-dimensional object printing method is implemented using the three-dimensional object printing apparatus 100A described above. As shown in FIG. 10, the three-dimensional object printing apparatus 100A sequentially performs a step S210 of implementing a non-printing operation, a step S220 of implementing a printing operation, and a step S230 of implementing a non-printing operation. Figure 12

[0113] The non-printing operation of the step S210 is an operation in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W before the printing operation. In the non-printing operation, the liquid discharge head 310 does not discharge ink. The non-printing operation includes, for example, a preparatory operation in which the robot 200 moves the liquid discharge head 310 to a printing start position of the first printing operation, and brings the rotation shafts O2, O3, and O5 into a state in which they are parallel to each other, and the like. In the non-printing operation, it is possible to cause all of the six joint sections 230 possessed by the robot 200 to operate, and thereby implement movement of the liquid discharge head 310 by operation of a larger number of joint sections 230 than in the printing operation.

[0114] ​​The printing operation of step S220 is an operation in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W, and an operation in which the liquid discharge head 310 discharges ink. This printing operation sequentially executes step S221 of performing a first printing operation, step S222 of driving the movable section 800, and step S223 of performing a second printing operation. In the first printing operation and the second printing operation, the movement of the liquid discharge head 310 is performed by the operation of three of the six joint sections 230 of the robot 200, as with the printing operation of the first embodiment described above. Therefore, compared with the non-printing operation, the deviation of the actual movement path of the liquid discharge head 310 from the ideal path is reduced. With regard to step S222, the description will be given below based on the description of step S222 of the second embodiment. Figure 13

[0115] The non-printing operation of step S230 is an operation in which the robot 200 changes the relative position of the liquid discharge head 310 with respect to the workpiece W after the printing operation. In this non-printing operation, the liquid discharge head 310 does not discharge ink. The non-printing operation includes, for example, an operation in which the robot 200 moves the liquid discharge head 310 from the printing end position of the second printing operation to another position, and the like. In the non-printing operation, all of the six joint sections 230 of the robot 200 can be operated, and thus the movement of the liquid discharge head 310 is performed by the operation of a larger number of joint sections 230 than in the printing operation. As an example of the other position, a position in which a maintenance unit (not shown) that performs maintenance of the liquid discharge head 310 is provided can be cited.

[0116] Figure 13 Fig. 9 is a diagram for explaining the first printing operation and the second printing operation. In Figure 13 Fig. 9, the movable section 800 and the liquid discharge head 310 during execution of the first printing operation are shown. The movable section 800 moves the workpiece W from the position shown in a solid line to the position shown in a two-dot chain line in the direction DT along the X axis during the period between the first printing operation and the second printing operation. The distance L of this movement is determined in accordance with the positional relationship between the first region RP1 and the second region RP2. In Figure 13 the example shown in Fig. 9, a part of the first region RP1 and the second region RP2 overlap each other. Therefore, the distance L is shortened by the length of the overlap amount compared with the width of the first region RP1 or the second region RP2 along the X axis. In addition, the first region RP1 and the second region RP2 can not overlap each other.

[0117] ​By the above second embodiment, it is also possible to improve the print quality as with the first embodiment described above. Further, in the present embodiment, as described above, the print operation performed in step S220 includes a first print operation performed in step S221 and a second print operation performed in step S223. The first print operation causes the M number of joint sections 230 to rotate and performs printing on the first region RPl of the workpiece W. The second print operation causes the M number of joint sections 230 to rotate and performs printing on a second region RP2 of the workpiece W that is different from the first region RPl. The robot 200 has a movable section 800. The movable section 800 moves the relative position of the workpiece W to the liquid discharge head 310 in a direction that is different during the first print operation and the second print operation from the direction during the performance of the first print operation and the second print operation. In the present embodiment, the direction is the XI direction. In this way, by moving the liquid discharge head 310 relative to the workpiece W independently of the plurality of joint sections 230 by the movable section 800, it is possible to perform printing on the first region RPl and the second region RP2 respectively without having to change the operation of the plurality of joint sections 230.

[0118] Further, although a structure in which the position relationship of the movable section 800 to the base 210 of the robot 200 is fixed is exemplified in the present embodiment, it is not limited to this structure. For example, by providing a movable section composed of a linear actuator between the liquid discharge head 310 and the tip of the arm 220 of the robot 200, the same effect as the present embodiment can be obtained.

[0119] 3. Modification

[0120] Each of the modes exemplified above can be modified in various ways. In the following, specific modification modes applicable to each of the modes described above will be exemplified. Further, two or more modes arbitrarily selected from the following examples can be appropriately combined within a range in which they do not contradict each other.

[0121] 3-1. Modification 1

[0122] Although a structure in which three joint sections 230 are caused to operate during the performance of the print operation is exemplified in the modes described above, it is not limited to this, and it is only necessary that the number of joint sections 230 caused to operate during the performance of the print operation be smaller than during the performance of the non-print operation. However, in terms of not limiting the shape of the workpiece W, it is preferable that three joint sections 230 whose rotation axes are parallel to each other be caused to operate as in the modes described above. Further, the rotation axes of the three joint sections 230 are not limited to the case of being orthogonal to the Z axis but are arbitrary.

[0123] 3-2. Modification 2

[0124] Although the structure of the vertical multi-axis robot using six axes is exemplified as the moving mechanism in the above-described manner, the structure is not limited to this. The moving mechanism only needs to be able to change the relative position and posture of the liquid discharge head three-dimensionally with respect to the work. Therefore, the moving mechanism can be, for example, a vertical multi-axis robot other than six axes, or a horizontal multi-axis robot. Furthermore, the robot arm can have an extension mechanism or the like in addition to the joint portion composed of the turning mechanism. However, from the viewpoint of balancing the printing quality in the printing operation and the degree of freedom of the operation of the moving mechanism in the non-printing operation, it is preferable that the moving mechanism be a multi-axis robot of six axes or more.

[0125] 3-3. Modification Example 3

[0126] Although the structure using screw fastening or the like is exemplified as the fixing method of the liquid discharge head with respect to the tip end of the robot in the above-described manner, the structure is not limited to this. For example, the liquid discharge head can be fixed with respect to the tip end of the robot by gripping the liquid discharge head with a gripper or the like installed at the tip end of the robot arm.

[0127] 3-4. Modification Example 4

[0128] Although the moving mechanism of the structure that moves the liquid discharge head is exemplified in the above-described manner, the structure is not limited to this, and, for example, the structure in which the position of the liquid discharge head is fixed, and the moving mechanism moves the work to change the relative position and posture of the work three-dimensionally with respect to the liquid discharge head. In this case, the work is gripped by a gripper or the like installed at the tip end of the robot arm.

[0129] 3-5. Modification Example 5

[0130] Although the structure in which printing is performed using one kind of ink is exemplified in the above-described manner, the structure is not limited to this, and the present application can also be applied to a structure in which printing is performed using two or more kinds of ink.

[0131] 3-6. Modification Example 6

[0132] The use of the three-dimensional object printing apparatus of the present application is not limited to printing. For example, the three-dimensional object printing apparatus that discharges a solution of a color material is utilized as a manufacturing apparatus that forms a color filter of a liquid crystal display device. Furthermore, the three-dimensional object printing apparatus that discharges a solution of a conductive material is utilized as a manufacturing apparatus that forms a wiring or an electrode of a wiring substrate. Furthermore, the three-dimensional object printing apparatus can also be utilized as a jet dispenser that applies an adhesive or the like to a work.

[0133] Symbol Explanation

[0134] 100 … Stereoscopic object printing device; 100A … Stereoscopic object printing device; 200 … Robot (moving mechanism); 230 … Joint section (joint); 230_1 … Joint section (second joint); 230_2 … Joint section (first joint); 230_3 … Joint section (fourth joint); 230_4 … Joint section; 230_5 … Joint section (third joint); 230_6 … Joint section; 310 … Liquid ejection head; 800 … Movable section; N … Nozzle; O1 … Rotation axis (second rotation axis); O2 … Rotation axis (first rotation axis); O3 … Rotation axis (fourth rotation axis); O4 … Rotation axis; O5 … Rotation axis (third rotation axis); O6 … Rotation axis; RP1 … First region; RP2 … Second region; RU … Movement path; RU_1 … First movement path; RU_2 … Second movement path; W … Workpiece.

Claims

1. A three-dimensional printing apparatus, characterized in that, have: A liquid ejector head that sprays liquid onto a three-dimensional workpiece; A robot, on which the liquid nozzle is mounted, and the relative position of the liquid nozzle with respect to the workpiece is changed. The robot has N joints capable of rotating around mutually different axes of rotation, where N is a natural number greater than 2. In the case of performing a printing action in which the relative position of the liquid nozzle changes relative to the workpiece by the robot and the liquid nozzle ejects liquid, Of the N joints, M are the joints that rotate during the printing action, where M is a natural number less than N. In the case where the robot performs a non-printing action that changes the relative position of the liquid nozzle with respect to the workpiece, but the liquid nozzle does not eject liquid, Of the N joints, the number of joints that rotate during the execution of the non-printing action is more than M but less than N.

2. The three-dimensional printing apparatus as described in claim 1, characterized in that, The N joints have: The first joint rotates about the first axis of rotation; The second joint rotates around the second axis of rotation; The third joint rotates around the third axis of rotation. During the printing process, the first joint and the third joint rotate, while the second joint does not rotate. At the start timing of the printing operation, the angle between the first rotating shaft and the third rotating shaft is smaller than the angle between the first rotating shaft and the second rotating shaft.

3. The three-dimensional printing apparatus as described in claim 2, characterized in that, The second rotation axis is the rotation axis among the N joints that has the largest angle with the first rotation axis.

4. The three-dimensional printing apparatus as described in claim 2, characterized in that, The first rotation axis and the third rotation axis are parallel to each other.

5. The three-dimensional printing apparatus as described in claim 2, characterized in that, The N joints also have a fourth joint, which rotates about a fourth rotation axis. At the start timing of the printing operation, the first rotating shaft, the third rotating shaft, and the fourth rotating shaft are parallel to each other. During the execution of the printing action, the first joint, the third joint, and the fourth joint rotate respectively.

6. The three-dimensional printing apparatus as described in claim 1, characterized in that, The liquid ejector head has multiple nozzles arranged along the nozzle column axis. The N joints include a first joint, which rotates about a first rotation axis. During the execution of the printing action, the first rotating shaft and the nozzle column shaft are parallel to each other.

7. The three-dimensional printing apparatus according to any one of claims 1 to 5, characterized in that, The printing process includes: The first printing action causes the M joints to rotate and print on a first area of ​​the workpiece; The second printing action involves rotating the M joints and performing printing on a second region of the workpiece, different from the first region. The robot has a movable part that, during the period between the first printing action and the second printing action, moves the relative position of the workpiece and the liquid nozzle in a direction different from that during the execution of the first printing action and the second printing action.

8. The three-dimensional printing apparatus according to any one of claims 1 to 5, characterized in that, The robot is a six-axis vertical joint robot. N is 6, and M is 3.

9. A three-dimensional printing apparatus, characterized in that, have: A liquid ejector head that sprays liquid onto a three-dimensional workpiece; A moving mechanism, on which the liquid nozzle is mounted, changes the relative position of the liquid nozzle with respect to the workpiece. The 3D printing apparatus performs the following actions: The printing action is the action of the moving mechanism changing the relative position of the liquid nozzle with respect to the workpiece, and the liquid nozzle ejecting liquid. The non-printing action refers to the action in which the moving mechanism changes the relative position of the liquid nozzle with respect to the workpiece, but the liquid nozzle does not spray liquid. In the three-dimensional printing apparatus, The moving mechanism has multiple joints capable of rotating about different axes of rotation. The plurality of joints includes: The first joint rotates during the execution of both the printing action and the non-printing action. The second joint does not rotate during the execution of the printing action, but rotates during the execution of the non-printing action; The third 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. During the printing process, the first joint and the third joint rotate, while the second joint does not rotate. At the start timing of the printing operation, the angle between the first rotating shaft and the third rotating shaft is smaller than the angle between the first rotating shaft and the second rotating shaft.

10. The three-dimensional printing apparatus as described in claim 9, characterized in that, The second rotation axis is the rotation axis among the plurality of joints that has the largest angle with the first rotation axis.

11. The three-dimensional printing apparatus as described in claim 9, characterized in that, The first rotation axis and the third rotation axis are parallel to each other.

12. The three-dimensional printing apparatus as described in claim 9, characterized in that, The plurality of joints also have a fourth joint, which rotates about a fourth rotation axis. At the start timing of the printing operation, the first rotating shaft, the third rotating shaft, and the fourth rotating shaft are parallel to each other. During the execution of the printing action, the first joint, the third joint, and the fourth joint rotate respectively.

13. The three-dimensional printing apparatus as described in claim 9, characterized in that, The liquid ejector head has multiple nozzles arranged along the nozzle column axis. During the execution of the printing action, the first rotating shaft and the nozzle column shaft are parallel to each other.

14. The three-dimensional printing apparatus according to any one of claims 9 to 12, characterized in that, The printing process includes: The first printing action causes M joints, including the plurality of joints, to rotate and print on a first area of ​​the workpiece. The second printing action involves rotating the M joints and performing printing on a second region of the workpiece, different from the first region. The moving mechanism has a movable part that, during the period between the first printing action and the second printing action, moves the relative position of the workpiece and the liquid nozzle in a direction different from that during the execution of the first printing action and the second printing action.

15. The three-dimensional printing apparatus according to any one of claims 9 to 12, characterized in that, The moving mechanism is a six-axis vertical joint robot.

16. A method for printing three-dimensional objects, characterized in that, Using liquid ejector heads and robots to print on three-dimensional workpieces. The liquid nozzle sprays liquid onto the workpiece. The robot is equipped with the liquid nozzle, and the relative position of the liquid nozzle with respect to the workpiece is changed. In the aforementioned three-dimensional printing method, The robot has N joints capable of rotating around mutually different axes of rotation, where N is a natural number greater than 2. In the case of performing a printing action in which the relative position of the liquid nozzle changes relative to the workpiece by the robot and the liquid nozzle ejects liquid, Of the N joints, M are the joints that rotate during the printing action, where M is a natural number less than N. In the case where the robot performs a non-printing action that changes the relative position of the liquid nozzle with respect to the workpiece, but the liquid nozzle does not eject liquid, Of the N joints, the number of joints that rotate during the execution of the non-printing action is more than M but less than N.

17. A method for printing three-dimensional objects, characterized in that, Using liquid ejector heads and a moving mechanism to print on three-dimensional workpieces. The liquid nozzle sprays liquid onto the workpiece. The liquid nozzle is mounted on the moving mechanism, and the relative position of the liquid nozzle with respect to the workpiece changes. In the aforementioned three-dimensional printing method, the following actions are performed: The printing action is the action of the moving mechanism changing the relative position of the liquid nozzle with respect to the workpiece, and the liquid nozzle ejecting liquid. The non-printing action refers to the action in which the moving mechanism changes the relative position of the liquid nozzle with respect to the workpiece, but the liquid nozzle does not spray liquid. The moving mechanism has multiple joints capable of rotating about different axes of rotation. The plurality of joints includes: The first joint rotates during the execution of both the printing action and the non-printing action. The second joint does not rotate during the execution of the printing action, but rotates during the execution of the non-printing action; The third 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. During the printing process, the first joint and the third joint rotate, while the second joint does not rotate. At the start timing of the printing operation, the angle between the first rotating shaft and the third rotating shaft is smaller than the angle between the first rotating shaft and the second rotating shaft.

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