Patent Application
20220126513
The present application is based on, and claims priority from JP Application Serial Number 2020-179514, filed Oct. 27, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a three-dimensional object printing apparatus and a three-dimensional object printing method.
A three-dimensional object printing apparatus that executes printing on a surface of three-dimensional work using an ink jet method is known. For example, a system described in JP-T-2015-520011 includes a multi-axis robot constituted by a plurality of movable joint members, and a print head disposed on the robot, and ejects ink droplets from the print head onto a curved surface of a vehicle.
A device described in JP-T-2015-520011 operates all the plurality of movable joint members included in the robot during printing. Therefore, the device described in JP-T-2015-520011 has a problem that operational errors of the movable joint members overlap to cause a significant deviation of an actual movement route of the print head from an ideal movement route of the print head, thereby reducing the printing quality.
To solve the foregoing problem, according to an aspect of the present disclosure, a three-dimensional object printing apparatus includes a liquid ejecting head that ejects a liquid to three-dimensional work, and a moving mechanism that changes a relative position of the liquid ejecting head with respect to the work. The moving mechanism includes a number N (N is a natural number of 2 or greater) of joints rotatable around different rotational axes. When a printing operation that causes the liquid ejecting head to eject a liquid while causing the moving mechanism to change the relative position of the liquid ejecting head with respect to the work is executed, the number of joints that rotate during the execution of the printing operation among the number N of joints is M (M is a natural number smaller than N).
According to another aspect of the present disclosure, a three-dimensional object printing apparatus includes a liquid ejecting head that ejects a liquid to three-dimensional work, and a moving mechanism that changes a relative position of the liquid ejecting head with respect to the work. The three-dimensional object printing apparatus executes a printing operation that causes the liquid ejecting head to eject a liquid while causing the moving mechanism to change the relative position of the liquid ejecting head with respect to the work, and a non-printing operation that causes the moving mechanism to change the relative position of the liquid ejecting head with respect to the work and does not cause the liquid ejecting head to eject a liquid. The moving mechanism includes a plurality of joints rotatable around different rotational axes. The plurality of joints include a first joint that rotates during the execution of the printing operation and the non-printing operation, and a second joint that does not rotate during the execution of the printing operation and rotates during the execution of the non-printing operation.
According to still another aspect of the present disclosure, a three-dimensional object printing method of executing printing on three-dimensional work using a liquid ejecting head that ejects a liquid to the work and a moving mechanism that changes a relative position of the liquid ejecting head with respect to the work is provided. The moving mechanism includes a number N (N is a natural number of 2 or greater) of joints rotatable around different rotational axes. When a printing operation that causes the liquid ejecting head to eject a liquid while causing the moving mechanism to change the relative position of the liquid ejecting head with respect to the work is executed, the number of joints that rotate during the execution of the printing operation among the number N of joints is M (M is a natural number smaller than N).
According to still another aspect of the present disclosure, a three-dimensional object printing method of executing printing on three-dimensional work using a liquid ejecting head that ejects a liquid to the work and a moving mechanism that changes a relative position of the liquid ejecting head with respect to the work is provided. The method includes executing a printing operation that causes the liquid ejecting head to eject a liquid while causing the moving mechanism to change the relative position of the liquid ejecting head with respect to the work, and executing a non-printing operation that causes the moving mechanism to change the relative position of the liquid ejecting head with respect to the work and does not cause the liquid ejecting head to eject a liquid. The moving mechanism includes a plurality of joints rotatable around different rotational axes. The plurality of joints include a first joint that rotates during the execution of the printing operation and the non-printing operation, and a second joint that does not rotate during the execution of the printing operation and rotates during the execution of the non-printing operation.
Hereinafter, embodiments of the present disclosure are described with reference to the accompanying drawings. Dimensions or scale of each of sections illustrated in the drawings may differ from actual dimensions or scale of each of the sections, and some sections are schematically illustrated in the drawings in order to easily understand the sections. The scope of the present disclosure is not limited to the embodiments unless otherwise stated in the following description to limit the present disclosure.
In the following description, an X axis, a Y axis, and a Z axis that intersect each other are used as appropriate. In addition, one direction in which the X axis extends is referred to as X1 direction, and the other direction in which the X axis extends is referred to as X2 direction. Similarly, one direction in which the Y axis extends is referred to as Y1 direction, and the other direction in which the Y axis extends is referred to as Y2 direction. Furthermore, one direction in which the Z axis extends is referred to as Z1 direction, and the other direction in which the Z axis extends is referred to as Z2 direction.
The X axis, the Y axis, and the Z axis are coordinate axes of a base coordinate system set in a space in which work W described later and a base 210 are placed. Typically, the Z axis is a vertical axis, and the Z2 direction corresponds to a downward direction in the vertical direction. The Z axis may not be the vertical direction. The X axis, the Y axis, and the Z axis are typically orthogonal to each other, but are not limited thereto. The X axis, the Y axis, and the Z axis may not be orthogonal to each other. For example, the X axis, the Y axis, and the Z axis may intersect each other at an angle ranging from 80° to 100°.
The work W has a surface WF targeted for printing. In an example illustrated in
In the example illustrated in
The robot 200 is a moving mechanism that changes the position and orientation of the liquid ejecting unit 300 with respect to the work W. In the example illustrated in
The base 210 holds the arm 220. In the example illustrated in
The arm 220 is a 6-axis robot arm having a proximal end attached to the base 210 and a distal end whose three-dimensional position and orientation are changed with respect to the proximal end. The arm 220 includes arms 221, 222, 223, 224, 225, and 226 coupled in this order.
The arm 221 is coupled to the base 210 via a joint section 230_1 and rotatable around a rotational axis O1. The arm 222 is coupled to the arm 221 via a joint section 230_2 and rotatable around a rotational axis O2. The arm 223 is coupled to the arm 222 via a joint section 230_3 and rotatable around a rotational axis O3. The arm 224 is coupled to the arm 223 via a joint section 230_4 and rotatable around a rotational axis O4. The arm 225 is coupled to the arm 224 via a joint section 230_5 and rotatable around a rotational axis O5. The arm 226 is coupled to the arm 225 via a joint section 230_6 and rotatable around a rotational axis O6. Each of the joint sections 230_1 to 230_6 is hereinafter referred to as joint section 230 in some cases.
Each of the joint sections 230_1 to 230_6 is an example of a “joint”. In the example illustrated in
Each of the joint sections 230_1 to 230_6 is a mechanism that couples one of two adjacent arms to the other arm in such a manner that the one arm is rotatable with respect to the other arm. Although not illustrated in
The rotational axis O1 is perpendicular to the placement surface to which the base 210 is fixed. The placement surface is not illustrated in
Regarding the rotational axes, the term “perpendicular” not only indicates that an angle formed by two rotational axes is 90° but also indicates that an angle formed by two rotational axes is in a range of 90°±5°. Similarly, the term “parallel” not only indicates that two rotational axes are completely parallel to each other but also indicates that one of two rotational axes is inclined by an angle of approximately ±5° with respect to the other rotational axis.
The liquid ejecting unit 300 is attached as an end effector to the distal end of the arm 220, that is, to the arm 226.
The liquid ejecting unit 300 is a device that includes a liquid ejecting head 310 that ejects ink toward the work W. The ink is an example of a liquid. In the first embodiment, the liquid ejecting unit 300 includes not only the liquid ejecting head 310 but also a pressure control valve 320 and a sensor 330. The pressure control valve 320 adjusts the pressure of ink to be supplied to the liquid ejecting head 310. The sensor 330 measures a distance from the liquid ejecting unit 300 to the work W. Since the liquid ejecting head 310, the pressure control valve 320, and the sensor 330 are fixed to the arm 226, relationships of the positions and orientation of the liquid ejecting head 310, the pressure control valve 320, and the sensor 330 are fixed.
The ink is not particularly limited. Examples of the ink are water-based ink in which a color material such as a dye or a pigment is dissolved in a water-based solvent, curable ink containing a curable resin such as an ultraviolet-curable resin, and solvent-based ink in which a color material such as a dye or a pigment is dissolved in an organic solvent. The ink is not limited to the solutions and may be ink in which a color material or the like is dispersed as a dispersoid in a dispersion medium. The ink is not limited to ink containing a color material and may be ink containing, as a dispersoid, conductive particles such as metal particles for forming a wiring or the like.
Although not illustrated in
The pressure control valve 320 is a valve mechanism that is opened and closed based on the pressure of ink within the liquid ejecting head 310. By opening and closing the pressure control valve 320, the pressure of the ink within the liquid ejecting head 310 is maintained in a predetermined negative pressure range. Therefore, ink menisci formed in the nozzles N of the liquid ejecting head 310 are stabilized. This prevents air bubbles from being inserted into the nozzles N and prevents ink from spilling out of the nozzles N.
The sensor 330 is an optical displacement sensor that measures the distance from the liquid ejecting head 310 to the work W. The sensor 330 is provided when necessary and may be omitted. In the example illustrated in
The liquid supply unit 400 is a mechanism for supplying ink to the liquid ejecting head 310. The liquid supply unit 400 includes a liquid container 410 and a supply flow path 420.
The liquid container 410 stores ink. The liquid container 410 is, for example, a bag-shaped ink pack formed of a flexible film.
In the example illustrated in
The liquid container 410 may be present at any position as long as ink can be supplied at predetermined pressure from the liquid container 410 to the liquid ejecting head 310. The liquid container 410 may be present on the lower side with respect to the liquid ejecting head 310 in the vertical direction. In this case, for example, a pump may be used to supply ink at predetermined pressure from the liquid container 410 to the liquid ejecting head 310.
The supply flow path 420 is a flow path through which ink is supplied from the liquid container 410 to the liquid ejecting head 310. The pressure control valve 320 is provided in the middle of the supply flow path 420. Therefore, even when a positional relationship between the liquid ejecting head 310 and the liquid container 410 is changed, it is possible to reduce a variation in the pressure of the ink within the liquid ejecting head 310.
The supply flow path 420 is constituted by an inner space of a tube, for example. The tube used for the supply flow path 420 is made of an elastic material such as a rubber material or an elastomer material and has flexibility. By constituting the supply flow path 420 using the tube having flexibility, a change in a relative positional relationship between the liquid container 410 and the pressure control valve 320 is allowed. Therefore, even when the position or orientation of the liquid ejecting head 310 is changed in a state in which the position and orientation of the liquid container 410 is fixed, it is possible to supply ink from the liquid container 410 to the pressure control valve 320.
A part of the supply flow path 420 may be constituted by a non-flexible member. A part of the supply flow path 420 may have a distribution flow path for distributing ink to a plurality of sections. A part of the supply flow path 420 may be integrated with the liquid ejecting head 310 or the pressure control valve 320.
The controller 600 is a robot controller that controls driving of the robot 200. Although not illustrated in
As illustrated in
The controller 600 has a function of controlling driving of the robot 200 and a function of generating a signal D3 to synchronize the ejection operation of the liquid ejecting head 310 with an operation of the robot 200. The controller 600 includes a storage circuit 610 and a processing circuit 620.
The storage circuit 610 stores various programs to be executed by the processing circuit 620 and various data to be processed by the processing circuit 620. For example, the storage circuit 610 includes either one or both of semiconductor memories that are a volatile memory such as a random-access memory (RAM) and a nonvolatile memory such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable ROM (PROM). A portion of the storage circuit 610 or the entire storage circuit 610 may be included in the processing circuit 620.
Route information Da is stored in the storage circuit 610. The route information Da indicates a route along which the liquid ejecting head 310 needs to move. Specifically, the route information Da includes information indicating a route along which a tool center point indicating the origin of a tool coordinate system needs to move. For example, the route information Da is represented using coordinate values of the base coordinate system. The route information Da is determined based on work information indicating the position and shape of the work W. The work information is obtained by associating information such as computer-aided design (CAD) data indicating the three-dimensional shape of the work W with the foregoing base coordinate system. The route information Da is input to the storage circuit 610 from the computer 700.
The processing circuit 620 controls operations of the joint sections 230_1 to 230_6 based on the route information Da and generates the signal D3. Specifically, the processing circuit 620 executes inverse kinematics calculation to convert the route information Da into operational amounts such as rotational angles and rotational speeds of the joint sections 230_1 to 230_6. The processing circuit 620 outputs control signals Sk_1 to Sk_6 based on output D1_1 to D1_6 from the encoders 241_1 to 241_6 included in the arm driving mechanism 240 of the robot 200 in such a manner that the operational amounts such as the actual rotational angles and rotational speeds of the joint sections 230_1 to 230_6 are the results of the foregoing calculation. The control signals Sk_1 to Sk_6 correspond to the joint sections 230_1 to 230_6 and control driving of the motors included in the corresponding joint sections 230. The output D1_1 to D1_6 corresponds to the encoders 241_1 to 241_6. Each of the output D1_1, the output D1_2, the output D1_3, the output D1_4, the output D1_5, and the output D1_6 is hereinafter referred to as output D1 in some cases.
The processing circuit 620 generates the signal D3 based on the output D1 from at least one of the encoders 241_1 to 241_6. For example, the processing circuit 620 generates, as the signal D3, a trigger signal including a pulse when the output D1 from one encoder 241 among the encoders 241_1 to 241_6 is a predetermined value.
The processing circuit 620 includes a processor such as one or more central processing units (CPUs), for example. The processing circuit 620 may include a programmable logic device such as a field-programmable gate array (FPGA) instead of or as well as the one or more CPUs.
The control module 500 is a circuit that controls the ejection operation of the liquid ejecting head 310 based on the signal D3 output from the controller 600 and print data from the computer 700. The control module 500 includes a timing signal generating circuit 510, a power supply circuit 520, a control circuit 530, and a drive signal generating circuit 540.
The timing signal generating circuit 510 generates a timing signal PTS based on the signal D3. The timing signal generating circuit 510 is constituted by a timer that starts generating the timing signal PTS upon detecting the signal D3 as a trigger.
The power supply circuit 520 receives power supplied from a commercial power supply not illustrated to generate predetermined various potentials. Each of the generated various potentials is appropriately supplied to each of the components of the three-dimensional object printing 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 ejecting unit 300. The power supply potential VHV is supplied to the drive signal generating circuit 540.
The control circuit 530 generates a control signal SI, a waveform specifying signal dCom, a latch signal LAT, a clock signal CLK, and a change signal CNG based on the timing signal PTS. The signals synchronize with the timing signal PTS. Among the signals, the waveform specifying signal dCom is input to the drive signal generating circuit 540 and the other signals are input to the liquid ejecting unit 300 and a switching circuit 340.
The control signal SI is a digital signal to specify operational states of the piezoelectric elements 311 included in the liquid ejecting head 310. Specifically, the control signal SI specifies whether a drive signal Com described later is to be supplied to the piezoelectric elements 311. For example, the control signal SI specifies whether ink is to be ejected from the nozzles corresponding to the piezoelectric elements 311, and specifies amounts of ink to be ejected from the nozzles. The waveform specifying signal dCom is a digital signal to define the waveform of the drive signal Com. The latch signal LAT and the change signal CNG are used together with the control signal SI and define the timing of driving the piezoelectric elements 311, thereby defining the timing of ejecting ink from the nozzles. The clock signal CLK synchronizes with the timing signal PTS and serves as a reference. Among the foregoing signals, signals to be input to the switching circuit 340 of the liquid ejecting unit 300 are described later in detail.
The control circuit 530 includes a processor such as one or more central processing units (CPUs), for example. The control circuit 530 may include a programmable logic device such as a field-programmable gate array (FPGA) instead of or as well as the one or more CPUs.
The drive signal generating circuit 540 generates the drive signal Com to drive each of the piezoelectric elements 311 included in the liquid ejecting head 310. Specifically, the drive signal generating circuit 540 includes a DA conversion circuit and an amplifying circuit, for example. In the drive signal generating circuit 540, the DA conversion circuit converts the waveform specifying signal dCOM from the control circuit 530 from a digital signal to an analog signal and the amplifying circuit uses the power supply potential VHV from the power supply circuit 520 to amplify the analog signal, thereby generating the drive signal Com. A waveform signal that is included in a waveform included in the drive signal Com and is to be supplied to the piezoelectric elements 311 is a drive pulse PD. The drive pulse PD is supplied to the piezoelectric elements 311 from the drive signal generating circuit 540 via the switching circuit 340. The switching circuit 340 switches, based on the control signal SI, whether at least a part of the waveform included in the drive signal Com is supplied as the drive pulse PD.
The computer 700 has a function of supplying information such as the route information Da to the controller 600 and a function of supplying information such as print data to the control module 500. The computer 700 according to the first embodiment is electrically coupled to the foregoing sensor 330 and supplies information for correction of the router information Da to the controller 600 based on a signal D2 from the sensor 330.
The following description is given using an a axis, a b axis, and a c axis that intersect each other as appropriate. One direction in which the a axis extends is referred to as a1 direction, and the other direction in which the a axis extends and that extends toward the opposite direction to the a1 direction is referred to as a2 direction. Similarly, one direction in which the b axis extends is referred to as b1 direction, and the other direction in which the b axis extends and that extends toward the opposite direction to the b1 direction is referred to as b2 direction. In addition, one direction in which the c axis extends is referred to as c1 direction, and the other direction in which the c axis extends and that extends toward the opposite direction to the c1 direction is referred to as c2 direction.
The a, b, and c axes are coordinate axes of the tool coordinate system set in the liquid ejecting unit 300. Relationships of relative positions and orientation of the a, b, and c axes with respect to the foregoing X, Y, and Z axes change due to an operation of the foregoing robot 200. In the example illustrated in
As described above, the liquid ejecting unit 300 includes the liquid ejecting head 310, the pressure control valve 320, and the sensor 330. The liquid ejecting head 310, the pressure control valve 320, and the sensor 330 are held by a holding body 350 indicated by a dashed-and-double-dotted line in
The holding body 350 is, for example, made of a metal material or the like and is a substantially rigid body. Although the holding body 350 is formed in a flat box shape in
The holding body 350 is attached to the distal end of the arm 220, that is, to the arm 226. Therefore, each of the liquid ejecting head 310, the pressure control valve 320, and the sensor 330 is fixed to the arm 226.
In the example illustrated in
The supply flow path 420 is sectioned by the pressure control valve 320 into an upstream flow path 421 and a downstream flow path 422. That is, the supply flow path 420 includes the upstream flow path 421 coupling the liquid container 410 to the pressure control valve 320, and the downstream flow path 422 coupling the pressure control valve 320 to the liquid ejecting head 310. In the example illustrated in
The liquid ejecting head 310 has a nozzle surface F and the plurality of nozzles N opened on the nozzle surface F. In the example illustrated in
The positions of the nozzles N of the first nozzle array La may match the positions of the nozzles N of the second nozzle array Lb in the direction along the b axis or may be different from the positions of the nozzles N of the first nozzle array Lb in the direction along the b axis. In addition, components relating to nozzles N of one of the first and second nozzle arrays La and Lb may be omitted. The configuration in which the positions of the nozzles N of the first nozzle array La match the positions of the nozzles N of the second nozzle array Lb in the direction along the b axis is exemplified below.
The non-printing operation of step S110 is an operation that causes the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W before the printing operation. In the non-printing operation of step S110, the liquid ejecting head 310 does not eject ink. The non-printing operation of step S110 includes a preparation operation such as an operation that causes the robot 200 to move the liquid ejecting head 310 to a printing start position and sets the rotational axis O2, the rotational axis O3, and the rotational axis O5 to be parallel to each other, for example. In the non-printing operation of step S110, all the six joint sections 230 included in the robot 200 can be operated and the liquid ejecting head 310 is moved by operations of a larger number of joint sections 230 than the number of joint sections 230 that are rotated in the printing operation.
The printing operation of step S120 is an operation that causes the liquid ejecting head 310 to eject ink while causing the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W. In the printing operation, the liquid ejecting head 310 is moved by operations of a smaller number of joint sections 230 than the number of joint sections 230 that are rotated in each of the non-printing operations. Therefore, as compared with the non-printing operations, a deviation of an actual movement route of the liquid ejecting head 310 from an ideal route of the liquid ejecting head 310 is reduced. In the printing operation according to the first embodiment, the liquid ejecting head 310 is moved by operations of three of the six joint sections 230 included in the robot 200. The printing operation is described later in detail.
The non-printing operation of step S130 is an operation that causes the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W after the printing operation. In the non-printing operation of step S130, the liquid ejecting head 310 does not eject ink. The non-printing operation of step S130 includes an operation such as an operation that causes the robot 200 to move the liquid ejecting head 310 from a printing end position to another position, for example. In the non-printing operation of step S130, all the six joint sections 230 included in the robot 200 can be operated and the liquid ejecting head 310 is moved by operations of a larger number of joint sections 230 than the number of joint sections 230 that are rotated in the printing operation.
As illustrated in
In the printing operation, the robot 200 rotates three of the six joint sections 230. In the example illustrated in
During the execution of the printing operation, the robot 200 rotates three of the six joint sections 230 in such a manner that the b axis of the tool coordinate system set in the liquid ejecting unit 300 is kept parallel to the Y axis of the base coordinate system. Specifically, during the execution of the printing operation, the robot 200 keeps the first and second nozzle arrays La and Lb parallel to the rotational axes of the three rotated joint sections 230. That is, during the execution of the printing operation, the robot 200 does not rotate the joint sections 230_1, 230_4, and 230_6 whose rotational axes are not parallel to the Y axis.
Although the printing operation according to the first embodiment sets the rotational axes O2, O3, and O5 to be parallel to each other, the printing operation is not limited thereto. For example, the printing operation may set the rotational axes O2, O3, and O6 to be parallel to each other. In this case, the liquid ejecting head 310 is moved along the movement route RU by operations of the joint sections 230_2, 230_3, and 230_6. In this case, a direction in which the liquid ejecting unit 300 is fixed to the arm 226 needs to be different from the direction indicated in the example of
In the first embodiment, as illustrated in
As indicated by a solid line in
As described above, the three-dimensional object printing apparatus 100 includes the liquid ejecting head 310 and the robot 200 that is an example of a “moving mechanism”. The liquid ejecting head 310 ejects ink onto the three-dimensional work W. The ink is an example of a “liquid”. The robot 200 changes the relative position of the liquid ejecting head 310 with respect to the work W. The robot 200 includes the joint sections 230 that are an example of a number N (N is a natural number of 2 or greater) of joint sections rotatable around different rotational axes. In the first embodiment, N is 6. As described above, the robot 200 includes the plurality of joint sections 230.
In the three-dimensional object printing apparatus 100, when the liquid ejecting head 310 executes the printing operation that causes the liquid ejecting head 310 to eject ink while causing the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W, the number of joint sections 230 that rotate during the execution of the printing operation among the number N of joint sections 230 is M (M is a natural number smaller than N). Since the number of joint sections 230 that rotate during the execution of the printing operation is M smaller than N, an effect of an operational error of the joint sections 230 is reduced and a deviation of the actual movement route of the liquid ejecting head 310 from the ideal movement route of the liquid ejecting head 310 can be reduced, as compared with a configuration in which the number of joint sections 230 that rotate during the execution of the printing operation is N. As a result, the printing quality can be improved.
On the other hand, in the three-dimensional object printing apparatus 100, when the liquid ejecting head 310 executes a non-printing operation that causes the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W and does not cause the liquid ejecting head 310 to eject ink, the number of joint sections that rotate during the execution of the non-printing operation among the number N of joint sections is larger than M and equal to or smaller than N. In the first embodiment, the plurality of joint sections 230 included in the robot 200 includes the joint section 230_2 that is an example of the “first joint” that rotates during the execution of the printing operation and the non-printing operation, and the joint section 230_1 that is an example of the “second joint” that does not rotate during the execution of the printing operation and rotates during the execution of the non-printing operation.
Since the number of joint sections 230 that rotate during the execution of the non-printing operation is larger than M, a degree of freedom of an operation of the robot 200 during the non-printing operation increases, as compared with a configuration in which the number of joint sections 230 that rotate during the execution of the non-printing operation is M. Therefore, the usability and the like during the non-printing operation can be improved, as compared with the case where the number of joint sections 230 is M.
In the first embodiment, as described above, the number N of joint sections 230 include the joint section 230_2 that is an example of the “first joint”, the joint section 230_1 that is an example of the “second joint”, and the joint section 230_5 that is an example of the “third joint”. The joint section 230_2 rotates around the rotational axis O2 that is an example of the “first rotational axis”. The joint section 230_1 rotates around the rotational axis O1 that is an example of the “second rotational axis”. The joint section 230_5 rotates around the rotational axis O5 that is an example of the “third rotational axis”.
In the three-dimensional object printing apparatus 100, during the execution of the printing operation, each of the joint sections 230_2 and 230_5 rotates and the joint section 230_1 does not rotate. At the start time of the printing operation, an angle formed by the rotational axis O2 and the rotational axis O5 is smaller than an angle formed by the rotational axis O2 and the rotational axis O1. In the first embodiment, the rotational axis O2 and the rotational axis O5 are parallel to each other and the angle formed by the rotational axis O2 and the rotational axis O5 is 0°. In the first embodiment, the rotational axis O2 and the rotational axis O1 are orthogonal to each other and the angle formed by the rotational axis O2 and the rotational axis O1 is 90°.
As described above, the rotational axis O1 forms the largest angle with the rotational axis O2 among angles formed by the rotational axes of the number N of joint sections 230 and the rotational axis O2. The “largest angle formed with the rotational axis O2” indicates that the angle is the closest to 90°.
In addition, as described above, the rotational axis O2 and the rotational axis O5 are parallel to each other. Therefore, by operating the joint section 230_2 and the joint section 230_5, the liquid ejecting head 310 can be linearly moved when viewed in a direction perpendicular to the rotational axis O2 or the rotational axis O5.
Specifically, the robot 200 can move the liquid ejecting head 310 in a direction parallel to a virtual plane formed by the X axis and the Z axis.
As described above, the number N of joint sections 230 include the joint section 230_3 that is an example of the “fourth joint”. The joint section 230_3 rotates around the rotational axis O3 that is an example of the “fourth rotational axis”. In the three-dimensional object printing apparatus 100, the rotational axes O2, O3, and O5 are parallel to each other at the start time of the printing operation, and the joint sections 230_2, 230_5, and 230_3 rotate during the execution of the printing operation. Therefore, while the distance from the liquid ejecting head 310 to the surface of the work W is maintained in a desirable range, the liquid ejecting head 310 can be linearly moved when viewed in a direction perpendicular to the rotational axis O2 or the rotational axis O5 by operating the joint sections 230_2, 230_5, and 230_3, regardless of the shape of the work W.
As described above, the liquid ejecting head 310 includes the plurality of nozzles N arranged along the b axis that is an example of a “nozzle array axis”. In the three-dimensional object printing apparatus 100, the rotational axis O2 and the b axis are parallel to each other during the execution of the printing operation. Therefore, by rotating the joint section 230_2 around the rotational axis O2 and moving the liquid ejecting head 310 in a direction orthogonal to the rotational axis O2, printing can be executed across the width of the plurality of nozzles N arranged along the b axis.
A second embodiment of the present disclosure is described below. In the second embodiment exemplified below, the reference signs used to describe the first embodiment are used for components whose effects and functions are the same as or similar to those in the first embodiment, and a detailed description of each of the components is omitted as appropriate.
The movable section 800 is a mechanism that operates independently of an operation of the robot 200 to relatively move the liquid ejecting head 310 with respect to the work W. In the example illustrated in
The movable section 800 with the foregoing configuration moves the work W from a first state in which the liquid ejecting head 310 faces a first region RP1 of the surface WF of the work W to a second state in which the liquid ejecting head 310 faces a second region RP2 of the surface WF of the work W. The second region RP2 is different from the first region RP1. In the first state, a first printing operation that causes the liquid ejecting head 310 to eject ink toward the first region RP1 while causing the robot 200 to move the liquid ejecting head 310 along a first movement route RU_1 is executed. In the second state, a second printing operation that causes the liquid ejecting head 310 to eject ink toward the second region RP2 while causing the robot 200 to move the liquid ejecting head 310 along a second movement route RU_2 is executed.
The non-printing operation of step S210 is an operation that causes the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W before the printing operation. In the non-printing operation of step S210, the liquid ejecting head 310 does not eject ink. The non-printing operation of step S210 includes a preparation operation such as an operation that causes the robot 200 to move the liquid ejecting head 310 to a printing start position of the first printing operation and sets the rotational axes O2, O3, and O5 to be parallel to each other. In the non-printing operation of step S210, all the six joint sections 230 included in the robot 200 can be operated and the liquid ejecting head 310 is moved by operations of a larger number of joint sections 230 than the number of joint sections 230 that are rotated in the printing operation.
The printing operation of step S220 is an operation that causes the liquid ejecting head 310 to eject ink while causing the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W. The printing operation executes step S221 of executing the first printing operation, step S222 of driving the movable section 800, and step S223 of executing the second printing operation in this order. In each of the first printing operation and the second printing operation, the liquid ejecting head 310 is moved by operations of three of the six joint sections 230 of the robot 200 in the same manner as the printing operation described in the first embodiment. Therefore, as compared with the non-printing operations, a deviation of an actual movement route of the liquid ejecting head 310 from an ideal movement route of the liquid ejecting head 310 is reduced. Step S222 is described later with reference to
The non-printing operation of step S230 is an operation that causes the robot 200 to change the relative position of the liquid ejecting head 310 with respect to the work W after the printing operation. In the non-printing operation of step S230, the liquid ejecting head 310 does not eject ink. The non-printing operation of step S230 includes an operation such as an operation that causes the robot 200 to move the liquid ejecting head 310 from a printing end position of the second printing operation to a different position from the printing end position. In the non-printing operation of step S230, all the six joint sections 230 of the robot 230 can be moved and the liquid ejecting head 310 is moved by operations of a larger number of joint sections 230 than the number of joint sections 230 that are rotated in the printing operation. An example of the different position is a position where a maintenance unit (not illustrated) that maintains the liquid ejecting head 310 is disposed.
Also in the second embodiment, the printing quality can be improved, like the first embodiment. In the second embodiment, as described above, the printing operation that is executed in step S220 includes the first printing operation that is executed in step S221 and the second printing operation that is executed in step S223. The first printing operation executes printing on the first region RP1 of the work W while rotating a number M of joint sections 230. The second printing operation executes printing on the second region RP2 different from the first region RP1 of the work W while rotating a number M of joint sections 230. The second region RP2 is different from the first region RP1. The robot 200 includes the movable section 800. In a time period between the first printing operation and the second printing operation, the movable section 800 changes the relative position of the liquid ejecting head 310 with respect to the work W to move the liquid ejecting head 310 toward a certain direction different from a direction toward which the liquid ejecting head 310 is moved during the execution of the first and second printing operations. In the second embodiment, the certain direction is the X1 direction. Since the movable section 800 relatively moves the liquid ejecting head 310 with respect to the work W without depending on the plurality of joint sections 230, printing can be executed on each of the first region RP1 and the second region RP2 without changing operations of the plurality of joint sections 230.
In the second embodiment, the configuration in which the positional relationship between the movable section 800 and the base 210 of the robot 200 is fixed is exemplified. However, the second embodiment is not limited thereto. For example, when a movable section constituted by a linear actuator is disposed between the liquid ejecting head 310 and the distal end of the arm 220 of the robot 200, the same effects as those obtained in the second embodiment can be obtained.
The embodiments exemplified above may be variously modified. Specific modifications that may be applied to each of the embodiments described above are exemplified below. Two or more aspects arbitrarily selected from the following examples may be combined in such a manner that the aspects do not contradict each other.
In the foregoing embodiments, the configuration in which three joint sections 230 are rotated during the execution of the printing operation is exemplified. However, the embodiments are not limited thereto. It is sufficient if the number of joint sections 230 that rotate during the execution of each of the printing operations is smaller than the number of joint sections 230 that rotate during the execution of each of the non-printing operations. However, since the shape of the work W is not limited, it is preferable that three joint sections 230 whose rotational axes are parallel to each other be rotate, as described in the embodiments. The rotational axes of the three joint sections 230 are not limited to be orthogonal to the Z axis and may be arbitrary.
In the foregoing embodiments, the configuration in which the 6-axis vertical articulated robot is used as the moving mechanism. However, the embodiments are not limited thereto. It is sufficient if the moving mechanism can three-dimensionally change the relative position and orientation of the liquid ejecting head with respect to the work. Therefore, the moving mechanism may be a vertical articulated robot other than a 6-axis vertical articulated robot or may be a horizontal articulated robot. In addition, the robot arm may include an extending and contracting mechanism or the like as well as the joint sections constituting a rotating mechanism. However, from the perspective of balance between the print qualities of the printing operations and the degree of freedom of an operation of the moving mechanism in the non-printing operations, the moving mechanism is preferably a 6- or more-axis articulated robot.
In the foregoing embodiments, the configuration in which screwing or the like is used to fix the liquid ejecting head to the distal end of the robot arm is exemplified. However, the embodiments are not limited to the configuration. For example, the liquid ejecting head may be fixed to the distal end of the robot arm by being gripped by a gripping mechanism such as a hand attached to the distal end of the robot arm.
In the foregoing embodiments, the moving mechanism configured to move the liquid ejecting head is exemplified. However, the embodiments are not limited thereto. For example, the position of the liquid ejecting head may be fixed and the moving mechanism may be configured to move the work and three-dimensionally change the relative position and orientation of the work with respect to the liquid ejecting head. In this case, for example, the work is gripped by a gripping mechanism such as a hand attached to the distal end of the robot arm.
In the foregoing embodiments, the configuration of executing printing using one type of ink is exemplified. However, the embodiments are not limited to this configuration. A configuration of executing printing using two or more types of ink is applicable to the present disclosure.
The use of the three-dimensional object printing apparatus according to the present disclosure is not limited to printing. For example, the three-dimensional object printing apparatus may eject a solution containing a coloring matter and may be used as a producing apparatus that forms a color filter of a liquid crystal display device. In addition, the three-dimensional object printing apparatus may eject a solution containing a conductive matter and may be used as a producing apparatus that forms a wiring and an electrode on a wiring substrate. Furthermore, the three-dimensional object printing apparatus may be used as a jet dispenser that applies a liquid such as an adhesive to work.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-179514 | Oct 2020 | JP | national |
