Printing method and robot system

Abstract

To provide a printing method and a robot system that are able to perform high quality printing.SOLUTION: There is provided a printing method for performing a printing operation on an object by ejecting ink from a print head while relatively moving the object and the print head, by using a robot including the print head. The robot includes a contact portion to be caused to contact the object. The method includes: using the robot, moving the contact portion with respect to the object while bringing the contact portion into contact with the object; detecting a shape of the object from a locus of the robot during the movement; and performing the printing operation based on the shape of the object.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a printing method and a robotic system. [Background technology]

[0002] The printing system described in Patent Document 1 prints on an object by ejecting ink from the print head toward the object while moving a robot equipped with a print head attached to its tip along a print track. The printing system also has a rotation angle sensor for detecting the actual position of the print head, and a piezo actuator that is disposed between the print head and corrects the position of the print head based on the actual position of the print head. By correcting the position of the print head based on the actual position of the print head, printing without strips (gaps) is achieved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-202781 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, one method for acquiring the shape of an object is to use CAD (Computer Aided Design) data of the object. However, the method using CAD data cannot deal with individual differences or positional deviations of the object, and may result in a decrease in print quality. [Means for solving the problem]

[0005] A printing method of the present invention is a printing method using a robot equipped with a print head, performing a printing job on an object by ejecting ink from the print head while moving the object and the print head relatively, comprising: the robot has a contact portion that contacts the object, Using the robot, the contact portion is moved relative to the object while being brought into contact with the object; Detecting a shape of the object from a trajectory of the robot during the movement; The printing job is performed based on the shape of the object.

[0006] The robot system of the present invention includes a robot having a robot arm and a print head and a contact unit that are disposed at a tip of the robot arm via a base; A control device for controlling the driving of the robot, the control device uses the robot arm to move the contact portion relative to the object while bringing the contact portion into contact with the object; Detecting a shape of the object from a trajectory of the tip of the robot arm during the movement; A printing job is performed on the object based on the shape of the object. [Brief description of the drawings]

[0007] [Figure 1] 1 is an overall view of a robot system according to a first embodiment. [Diagram 2] 2 is a plan view showing a moving stage provided in the robot shown in FIG. 1. [Diagram 3] 2 is a side view showing the tip portion of the robot shown in FIG. 1. [Figure 4] 11 is a flowchart illustrating a printing method. [Diagram 5] FIG. [Figure 6] 4 is a time chart showing an example of ink ejection timing. [Figure 7] FIG. [Figure 8] 1A and 1B are diagrams for explaining problems with a conventional printing method. [Figure 9] 1A and 1B are diagrams for explaining problems with a conventional printing method. [Figure 10]1A and 1B are diagrams for explaining problems with a conventional printing method. [Figure 11] 1A and 1B are diagrams for explaining a method for detecting the shape of an object. [Figure 12] 1A and 1B are diagrams for explaining a method for detecting the shape of an object. [Figure 13] FIG. 4 is a diagram illustrating an example of ink ejection timing. [Figure 14] FIG. 11 is a diagram for explaining a separation distance detection step. [Figure 15] 14 is a diagram showing the ink ejection timing obtained by correcting the ink ejection timing shown in FIG. 13. FIG. [Figure 16] 11 is a diagram showing a configuration of a tip portion of a robot included in a robot system according to a second embodiment. FIG. [Figure 17] 1A and 1B are diagrams for explaining a method for detecting the shape of an object. [Figure 18] 1A and 1B are diagrams for explaining a method for detecting the shape of an object. [Figure 19] 13A to 13C are diagrams illustrating a printing method using a robot system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a printing method and a robot system according to the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0009] First Embodiment FIG. 1 is an overall view of a robot system according to a first embodiment. FIG. 2 is a plan view showing a moving stage provided in the robot shown in FIG. 1. FIG. 3 is a side view showing the tip of the robot shown in FIG. 1. FIG. 4 is a flow chart for explaining a printing method. FIG. 5 is a diagram showing a printing operation. FIG. 6 is a time chart showing an example of ink ejection timing. FIG. 7 is a diagram showing a printing operation. FIGS. 8 to 10 are diagrams for explaining problems with the conventional printing method. FIGS. 11 and 12 are diagrams for explaining a method for detecting the shape of an object. FIG. 13 is a diagram showing an example of ink ejection timing. FIG. 14 is a diagram for explaining a separation distance detection step. FIG. 15 is a diagram showing ink ejection timing obtained by correcting the ink ejection timing shown in FIG. 13.

[0010] The robot system 1 shown in FIG. 1 is applied to a printing system that performs a printing operation on an object W. The robot system 1 has a robot 10 and a control device 9 that controls the driving of the robot 10. The robot 10 also has a robot body 2, a moving stage 4 arranged at the tip of the robot body 2, a force sensor 7 arranged between the moving stage 4 and the robot body 2, a print head 3 and a contact jig 6 arranged on the moving stage 4, and a vibration meter 5 arranged on the print head 3. In this robot system 1, a printing operation on the object W is performed by ejecting ink I from the print head 3 while moving the print head 3 relative to the object W using a robot arm 22.

[0011] <Robot body 2> The robot body 2 is a six-axis vertical articulated robot having six drive axes, and includes a base 21 fixed to a mounting table, a floor, or the like, and a robot arm 22 rotatably connected to the base 21. The robot arm 22 is configured with six arms 221, 222, 223, 224, 225, and 226 rotatably connected in this order from the base 21 side, and includes six joints J1, J2, J3, J4, J5, and J6. Among the joints J1 to J6, the joints J2, J3, and J5 are bending joints, and the joints J1, J4, and J6 are torsion joints. In addition, a drive mechanism including a motor and an encoder that detects the amount of rotation of the joint is installed in each of the joints J1, J2, J3, J4, J5, and J6. By independently moving each of the joints J1, J2, J3, J4, J5, and J6, the print head 3 attached to the tip of the robot arm 22 can be moved in a desired direction, at a desired attitude, and at a desired speed.

[0012] However, the configuration of the robot body 2 is not particularly limited. For example, the number of arms provided on the robot arm 22 is not limited to six. The robot body 2 may be a dual-arm robot, a horizontally articulated robot (SCARA robot), or the like. The robot body 2 may be self-propelled without being fixed to a stand, floor, or the like.

[0013] <Force Sensor 7> The force sensor 7 is disposed at the tip of the robot arm 22, i.e., on the arm 226. The force sensor 7 has three detection axes perpendicular to each other, and can independently detect a translational force (axial force) along each detection axis and a rotational force (torque) around each detection axis. In the robot system 1, the force sensor 7 is used to detect contact between the contact jig 6 and the object W. Note that the configuration of the force sensor 7 is not particularly limited as long as it can detect contact between the contact jig 6 and the object W.

[0014] <Mobile Stage 4> As shown in FIG. 1, the moving stage 4 is disposed on the tip side of the force sensor 7. The moving stage 4 is used to correct the position of the print head 3. As shown in FIG. 2, the moving stage 4 has a base 40 supported by the force sensor 7, a first stage 41 that moves linearly in a first direction A relative to the base 40, and a second stage 42 that moves linearly in a second direction B perpendicular to the first direction A relative to the first stage 41. The print head 3 and the contact jig 6 are disposed on the second stage 42 via a base 43. In this way, by disposing the print head 3 and the contact jig 6 on the base 43, the print head 3 and the contact jig 6 can be attached to and detached from the robot body 2 together with the base 43. This makes it easy to perform the attachment and detachment work.

[0015] The moving stage 4 also has a first stage driving unit 45 that moves the first stage 41 relative to the base 40 along the first direction A, and a second stage driving unit 46 that moves the second stage 42 relative to the first stage 41 along the second direction B. The first and second stage driving units 45 and 46 each have a piezoelectric actuator 400 that is driven by utilizing the expansion and contraction of a piezoelectric element caused by energization, and move the first and second stages 41 and 42 by transmitting the vibration of the piezoelectric actuator 400 to them. In this way, by using the piezoelectric actuator 400, the movement amount and movement speed of the first and second stages 41 and 42 can be finely and highly accurately controlled, and the movement direction can be quickly switched. In addition, the moving stage 4 can be made smaller and lighter. Therefore, the position correction of the print head 3 can be performed with higher accuracy.

[0016] However, the configuration of the moving stage 4 is not particularly limited. For example, the first and second stage driving units 45, 46 may be configured to use a driving source other than the piezoelectric actuator 400, such as a motor that rotates when energized. Furthermore, the moving stage 4 may further include a third stage that moves linearly in a direction perpendicular to the first direction A and the second direction B, and a fourth stage that moves rotationally around an axis perpendicular to the first direction A and the second direction B. The moving stage 4 may also be omitted. In this case, the position of the print head 3 may be corrected by the robot arm 22.

[0017] <Print Head 3> As shown in FIG. 3, the print head 3 is disposed on the second stage 42 of the moving stage 4 via a base 43. The print head 3 is not particularly limited, but in this embodiment, a piezoelectric inkjet head is used. The piezoelectric inkjet head has an ink chamber, a vibration plate constituting a part of the wall surface of the ink chamber, a piezoelectric element for vibrating the vibration plate, and a nozzle connected to the ink chamber. In this configuration, when a voltage is applied to the piezoelectric element to vibrate the piezoelectric element, the vibration plate vibrates and the ink I in the ink chamber is ejected from the nozzle. Also, as shown in FIG. 2 and FIG. 3, five nozzles 31 are formed on the tip surface of the print head 3 in a line in a direction perpendicular to the print track Q, that is, the movement direction of the print head 3 during printing work. Also, from each nozzle 31, ink I of the same color, for example, black ink I, is ejected. Then, while moving the print head 3 along the print trajectory Q, ink I is ejected from each nozzle 31 at a predetermined timing to land on the target W, thereby printing a predetermined print image on the target W. In this way, by having multiple nozzles 31 aligned in a direction intersecting the print trajectory Q, the printing range per scan of the print head 3 is expanded, and printing work can be performed efficiently.

[0018] However, the configuration of the print head 3 is not particularly limited. For example, the number and arrangement of the nozzles 31, the color of the ink I ejected from the nozzles 31, etc. are not particularly limited. For example, the print head 3 may have nozzles 31 that eject cyan ink I, nozzles 31 that eject magenta ink I, nozzles 31 that eject yellow ink I, and nozzles 31 that eject black ink I, and is capable of full-color printing of the CMYK color model. In this case, the nozzles of each color may be arranged side by side in a direction along the print trajectory Q.

[0019] Furthermore, the configuration of the print head 3 is not limited to the above-mentioned piezo-driven inkjet head, but may be, for example, an inkjet head of a thermal type that utilizes the film boiling phenomenon of the ink I, a bubble ejection type that ejects the ink I by generating bubbles in the ink I by applying heat, or an electrostatic actuator type that ejects the ink I by displacing and vibrating a vibration plate by electrostatic force.

[0020] ≪Vibration meter 5≫ As shown in Fig. 1, the vibration meter 5 is disposed on the print head 3 and detects vibrations of the print head 3. Note that the "vibration" refers to displacements other than the displacement along the print trajectory Q of the print head 3. The vibration meter 5 is not particularly limited as long as it can detect vibrations, and for example, a three-axis angular velocity sensor that detects angular velocities in three mutually perpendicular axial directions can be used.

[0021] <Contact jig 6> As shown in FIG. 3, the contact jig 6 is disposed on the base 43 and is arranged alongside the print head 3. The contact jig 6 has a base 61 extending in the normal direction of the second stage 42, that is, in a direction perpendicular to the first direction A and the second direction B, and a contact portion 62 disposed at the tip of the base 61. The contact portion 62 is a rotating body made of a cylindrical roller and can rotate around a rotation axis JJ relative to the base 61. The rotation axis JJ is parallel to the direction in which the five nozzles 31 are arranged. The contact portion 62 is disposed at a position protruding from the print head 3. In other words, the separation distance D6 between the tip of the contact portion 62 and the base 43 is greater than the separation distance D3 between the tip of the print head 3 and the base 43. In this way, by making D6>D3, the contact portion 62 can be easily brought into contact with the object W without being hindered by the print head 3, as described later.

[0022] However, the configuration of the contact jig 6 is not particularly limited. For example, a ball that can freely rotate in any direction relative to the base 61 may be used as the contact portion 62. Also, the contact portion 62 may not be a rotating body and may be fixed to the base 61. In this case, it is preferable to apply a treatment to the surface of the contact portion 62 to reduce frictional resistance, such as a fluorine-based coating.

[0023] <Control device 9> As shown in Fig. 1, the control device 9 is electrically connected to the robot 10 and controls the driving of the robot 10. Specifically, the control device 9 controls the driving of the robot body 2, the print head 3, the moving stage 4, the vibration meter 5, and the force sensor 7, either independently or in conjunction with each other. Such a control device 9 is, for example, composed of a computer, and has a processor (CPU) for processing information, a memory communicatively connected to the processor, and an external interface for connecting to an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute the programs stored in the memory.

[0024] The configuration of the robot system 1 has been described above. Next, a printing method for an object W using the robot system 1 will be described. As shown in FIG. 4, the printing method includes a separation distance detection step S1 for detecting a separation distance D between the print head 3 and the object W during printing, and a printing step S2 for driving the print head 3 based on the separation distance D detected in the separation distance detection step S1 to perform printing on the object W. The shape of the object W, more specifically, the shape of the surface to be printed on the object W is not particularly limited, but is preferably a non-flat surface such as a curved surface, a bent surface, or a surface that combines these, that is, a three-dimensional shape other than a flat surface. This makes the effect of the printing method of this embodiment more pronounced. Below, these steps S1 and S2 will be described in detail, but before that, the features of the printing method of this embodiment will be briefly described.

[0025] As an example, as shown in Fig. 5, an image P is printed by ejecting ink I from each nozzle 31 while moving the print head 3 along a print trajectory Q that maintains an ideal distance D0 from a planar target object W0. Fig. 6 also shows the timing of ink ejection from each nozzle 31 when printing. In this figure, the timing "1" means that ink I is ejected from each nozzle 31. Note that in the following, the five nozzles 31 may be described as 31a, 31b, 31c, 31d, and 31e.

[0026] In contrast, Fig. 7 shows how printing is performed by ejecting ink I from each nozzle 31 while moving the print head 3 along a print trajectory Q that maintains an ideal distance D0 from the target object W, which has an arc-shaped curved surface. Here, when printing an image P of the same shape as in Fig. 5 on the curved target object W, the flat image P must be printed in a curved form along the target object W, as shown in Fig. 8. However, when printing is performed on the target W with the ink ejection timing shown in Fig. 6, the shape of the image P that is planarly projected onto the target object W is printed on the target W, as shown in Fig. 9, and the image P is distorted.

[0027] Specifically, as shown in FIG. 10, when the center of the print head 3 faces the target object W at the closest distance, the greater the distance d from the center of the print head 3 to the nozzle 31, the greater the deviation of the actual landing position of the ink I from the target landing position T in a direction perpendicular to the print trajectory Q. Therefore, the image P printed on the target object W is distorted so as to extend in a direction perpendicular to the print trajectory Q. This results in a significant decrease in print quality. Note that the deviation of the actual landing position from the target landing position T increases as the radius of curvature of the target object W decreases and as the distance d to the nozzle 31 increases. Below, factors that cause such a decrease in print quality are also referred to as "quality degradation factors."

[0028] The printing method of the present embodiment aims to suppress the deterioration of print quality due to the above-mentioned quality deterioration factors and improve print quality. Simply put, in the printing method of the present embodiment, when the separation distance D between the nozzle 31 and the target object W exceeds a preset threshold SH, the ink I is not ejected from that nozzle 31. According to this method, since the ink I is not ejected from the nozzle 31 with a large separation distance D, it is possible to suppress the deviation of the actual landing position from the target landing position T caused by the quality deterioration factors. In other words, it is possible to accurately land the ink I at the target landing position without being affected by the quality deterioration factors. Therefore, it is possible to perform high-quality printing.

[0029] The separation distance detection step S1 and the printing step S2 of the printing method of this embodiment will be described in detail below.

[0030] <<Separation distance detection step S1>> In the separation distance detection step S1, the control device 9 first detects the shape of the target object W. Specifically, the control device 9 first moves the robot arm 22 to bring the contact portion 62 of the contact jig 6 into contact with the surface of the target object W, as shown in FIG. 11. Then, the control device 9 moves the robot arm 22 along the arrow G1 so as to roll the contact portion 62 on the target object W while maintaining the contact portion 62 in contact with the target object W, as shown in FIG. 12. In addition, at this time, the control device 9 feeds back the force detected by the force sensor 7, and moves the robot arm 22 up and down in the direction of the arrow G2 so that the pressing force F, which is the force with which the contact portion 62 presses the target object W, is constant or falls within a predetermined range during the movement of the contact portion 62. As a result, the tip of the robot arm 22 moves up and down in accordance with the shape of the target object W.

[0031] The control device 9 detects such up and down movement of the tip of the robot arm 22 based on the amount of rotation of each joint J1, J2, J3, J4, J5, J6 calculated from the output of an encoder provided at each joint J1, J2, J3, J4, J5, J6. As a result, shape data for one row of the object W shown in Fig. 12 is obtained. The control device 9 performs this operation the required number of times over the entire printing surface of the object W, and detects the shape of the object W by combining the shape data for each row.

[0032] According to such a method, the shape of the object W can be detected simply and accurately. Moreover, as an advantage over detecting the shape of the object W using CAD data, for example, the individual differences of the object W can be cancelled. In other words, shape errors specific to each object can be detected. Moreover, it is possible to deal with positional deviations of the object W from a designated placement location. Therefore, compared to detecting the shape of the object W using CAD data, variations in print quality between objects are suppressed, and the yield is increased. As a result, high-quality printing can be performed efficiently.

[0033] In particular, in this embodiment, the pressing force F of the contact portion 62 is constant while the contact portion 62 is being moved. Therefore, the contact portion 62 can be moved smoothly in the direction of the arrow G1, and deformation of the object W caused by fluctuations in the pressing force F can also be suppressed. Therefore, the shape of the object W can be detected with higher accuracy, and printing of higher quality can be performed. Also, in this embodiment, the contact portion 62 is a rotating body and moves by rolling on the object W, so that the frictional resistance between the contact portion 62 and the object W can be reduced. Therefore, wear of the contact portion 62 and scratches on the object W can be effectively suppressed.

[0034] Next, the control device 9 determines the print trajectory Q of the print head 3 based on the detected shape of the object W. In other words, it determines how the print head 3 should be moved relative to the object W in order to print a predetermined print image on the object W. This print trajectory Q also includes information on the movement speed of the print head 3. Note that in this process, it is preferable to determine the print trajectory Q on the premise that ink I is ejected from all nozzles 31. This maximizes the range that can be printed in one scan, making it possible to determine a more efficient print trajectory Q. However, the method of setting the print trajectory Q is not particularly limited as long as it is possible to print a predetermined image on the object W.

[0035] Next, the control device 9 determines the ink ejection timing for ejecting the ink I from each of the nozzles 31a, 31b, 31c, 31d, and 31e based on the determined print trajectory Q and the print image to be printed on the target object W. The ink ejection timing is determined, for example, as shown in Fig. 13, by selecting "no ejection: 0" or "ejection: 1" for each of the nozzles 31a, 31b, 31c, 31d, and 31e for each ejection cycle of the ink I.

[0036] Next, the control device 9 calculates the separation distance D between each nozzle 31 and the target object W for each ejection cycle of the ink I based on the determined print trajectory Q. That is, as shown in FIG. 14, the control device 9 calculates the separation distance D between the nozzle 31a and the target object W, the separation distance D between the nozzle 31b and the target object W, the separation distance D between the nozzle 31c and the target object W, the separation distance D between the nozzle 31d and the target object W, and the separation distance D between the nozzle 31e and the target object W. The separation distance D is a separation distance along the ejection direction of the ink I. Then, the control device 9 determines whether or not the calculated separation distance D exceeds a predetermined threshold value SH for each ejection cycle of the ink I. The threshold value SH can be appropriately set based on an ideal separation distance preset in the print head 3, for example, and is set to 3 mm in this embodiment.

[0037] Next, the control device 9 corrects the ink ejection timing shown in Fig. 13 based on the determination result. Specifically, as shown in Fig. 15, among the points where "ejection: 1" is set in the ink ejection timing shown in Fig. 13, a correction is performed to change the points where the separation distance D exceeds the threshold value SH to "not ejection: 0". Then, in the next printing step S2, ink I is ejected from each nozzle 31 based on the corrected ink ejection timing shown in Fig. 15, thereby effectively suppressing the deviation of the actual landing position from the target landing position T due to the above-mentioned quality degradation factors. Therefore, high-quality printing is possible.

[0038] <Printing step S2> In the printing step S2, the control device 9 drives the robot arm 22 to move the print head 3 along the print trajectory Q, while controlling the drive of the print head 3 based on the ink ejection timing shown in FIG. 15 determined in the separation distance detection step S1, thereby performing a printing operation. This effectively suppresses the deviation of the actual landing position from the target landing position T, and high-quality printing with less deviation, blurring, distortion, etc. is performed on the target object W. In addition, the control device 9 detects vibration of the print head 3 based on the output of the vibration meter 5 during the printing operation, and controls the drive of the moving stage 4 so that the detected vibration is canceled. Specifically, the control device 9 controls the drive of the moving stage 4 so that vibration of the opposite phase to the detected vibration is applied to the print head 3. This suppresses vibration of the print head 3 during the printing operation, enabling higher quality printing.

[0039] During the printing operation, it is preferable that the contact portion 62 does not come into contact with the target object W. This effectively prevents a decrease in print quality due to deviation from the printing trajectory Q or deformation of the target object W. For example, the contact jig 6 is detachable from the base 43, and the printing step S2 may be performed with the contact jig 6 removed.

[0040] The robot system 1 has been described above. As described above, the printing method using the robot system 1 is a printing method in which a robot 10 having a print head 3 is used to perform a printing operation on an object W by ejecting ink I from the print head 3 while moving the object W and the print head 3 relatively, and the robot 10 has a contact part 62 that is brought into contact with the object W, and the robot 10 is used to move the contact part 62 relative to the object W while being brought into contact with the object W, and the shape of the object W is detected from the trajectory of the robot 10 during the movement, and the printing operation is performed based on the shape of the object W. According to this printing method, the shape of the object W can be detected in a simple manner and with high accuracy. In addition, as an advantage over the case where the shape of the object W is detected using CAD data, for example, the individual differences of the object W can be canceled. In other words, shape errors specific to each individual can be detected. In addition, it is also possible to deal with positional deviations from the designated placement location of the object W. Therefore, compared to the case where the shape of the object W is detected using CAD data, the variation in print quality between individuals is suppressed, and the yield is increased. As a result, high-quality printing can be efficiently performed.

[0041] As described above, the print head 3 has nozzles 31 that eject ink I, and during printing, if the distance D between the nozzles 31 and the target object W exceeds a threshold SH, the ink I is not ejected from the nozzles 31. This method effectively prevents the actual landing position from shifting from the target landing position T, and enables high-quality printing on the target object W with little shifting, blurring, distortion, etc.

[0042] As described above, the target object W has a three-dimensional shape. This makes the effect of controlling the nozzle 31 not to eject the ink I when the separation distance D between the nozzle 31 and the target object W exceeds the threshold SH more pronounced.

[0043] As described above, the nozzles 31 are arranged in a line in the direction in which the print head 3 moves during printing, that is, in a direction that intersects with the printing trajectory Q. This expands the range that can be printed in one scan, allowing for efficient printing.

[0044] As described above, the robot system 1 includes the robot 10 having the robot arm 22, the print head 3 and the contact unit 62 disposed at the tip of the robot arm 22 via the base 43, and the control device 9 for controlling the driving of the robot 10. The control device 9 uses the robot arm 22 to move the contact unit 62 relative to the object W while contacting the object W, detects the shape of the object W from the trajectory of the tip of the robot arm 22 during the movement, and performs a printing operation on the object W based on the shape of the object W. With this configuration, the shape of the object W can be detected in a simple manner with high accuracy. In addition, as an advantage over the case where the shape of the object W is detected using CAD data, for example, the individual differences of the object W can be canceled. In other words, shape errors specific to each object can be detected. In addition, it is also possible to deal with positional deviations from the designated placement location of the object W. Therefore, compared to the case where the shape of the object W is detected using CAD data, the variation in print quality between individuals is suppressed, and the yield is increased. As a result, high-quality printing can be efficiently performed.

[0045] As described above, the print head 3 has nozzles 31 that eject ink I, and the control device 9 does not eject ink I from the nozzles 31 when the separation distance D between the nozzles 31 and the target object W exceeds a threshold value SH. This type of control effectively reduces deviation of the actual landing position from the target landing position T, enabling high-quality printing on the target object W with little deviation, blurring, distortion, etc.

[0046] As described above, the robot 10 has the force sensor 7 disposed between the base 43 and the robot arm 22. With this configuration, the pressing force F of the contact portion 62 can be kept constant while the contact portion 62 is being moved. This allows the contact portion 62 to be moved smoothly, and furthermore, deformation of the target object W caused by fluctuations in the pressing force F can be suppressed. This allows the shape of the target object W to be detected with higher accuracy, enabling printing of higher quality to be performed.

[0047] As described above, the contact portion 62 is a rotating body that rotates and moves relative to the object W. This can reduce the frictional resistance between the contact portion 62 and the object W, and can effectively suppress wear of the contact portion 62 and scratches on the object W.

[0048] <Second embodiment> Fig. 16 is a diagram showing the configuration of the tip of the robot included in the robot system according to the second embodiment. Fig. 17 and Fig. 18 are diagrams for explaining a method for detecting the shape of an object.

[0049] This embodiment is similar to the first embodiment described above, except for the configuration of the robot 10. In the following description, the present embodiment will be described focusing on the differences from the first embodiment described above, and a description of the similarities will be omitted. In each drawing of this embodiment, the same reference numerals are used for the same configurations as those in the previously described embodiment.

[0050] In the first embodiment described above, the shape of the object W is detected based on the up and down movement of the robot arm 22 when the contact portion 62 is moved in a rolling manner on the object W, but in this embodiment, the shape of the object W is detected using a support mechanism 8 attached to the robot body 2. Hereinafter, this support mechanism 8 will be described in detail.

[0051] 16, the support mechanism 8 is disposed between the robot arm 22 and the contact portion 62, more specifically, between the second stage 42 and the base 43, and allows the contact portion 62 to be displaced relative to the robot arm 22. Such a support mechanism 8 has a fixed portion 81 fixed to the second stage 42, a movable portion 82 that displaces relative to the fixed portion 81, a biasing portion 83 that biases the movable portion 82 relative to the fixed portion 81, and a displacement amount detection portion 84 that detects the amount of displacement of the movable portion 82 relative to the fixed portion 81. The base 43 is fixed to the movable portion 82.

[0052] The movable part 82 is displaceable relative to the fixed part 81 in a normal direction of the second stage 42, that is, in a direction perpendicular to the first direction A and the second direction B. In addition, the biasing part 83 is disposed between the fixed part 81 and the movable part 82, and biases the movable part 82 in a direction away from the fixed part 81. This makes it possible to press the contact part 62 against the object W. The biasing part 83 is not particularly limited, but may be, for example, a compression coil spring.

[0053] The displacement amount detection unit 84 detects the amount of displacement of the movable part 82 relative to the fixed part 81, that is, the amount of displacement of the contact part 62 relative to the robot arm 22. Such a displacement amount detection unit 84 is a reflective linear encoder, and has a light receiving / emitting element 841 arranged in the fixed part 81, and a scale 842 arranged in the movable part 82. In such a configuration, the scale 842 displaces relative to the light receiving / emitting element 841 in conjunction with the displacement of the movable part 82, so that the amount of displacement of the movable part 82 relative to the fixed part 81 can be detected by detecting the amount of displacement of the scale 842. However, the configuration of the displacement amount detection unit 84 is not particularly limited as long as it can detect the amount of displacement of the movable part 82 relative to the fixed part 81.

[0054] In the robot system 1 configured as above, the control device 9 detects the shape of the target object W in the following manner.

[0055] The control device 9 first moves the robot arm 22 to bring the contact portion 62 of the contact jig 6 into contact with the surface of the target object W, as shown in Fig. 17. Then, the control device 9 moves the robot arm 22 along the arrow G1 in a manner of rolling the contact portion 62 over the target object W while maintaining the contact portion 62 in contact with the target object W, as shown in Fig. 18. Then, the support mechanism 8 expands and contracts in accordance with the shape of the target object W, and the contact portion 62 moves up and down. The control device 9 detects the amount of vertical displacement of the movable portion 82 at this time based on the displacement amount detection unit 84. As a result, shape data of one row of targets W shown in Fig. 18 is obtained.

[0056] The control device 9 performs this operation the required number of times over the entire printing surface of the object W, and detects the shape of the object W by combining the shape data of each row. With this configuration, the shape of the object W can be detected simply and accurately. In the state shown in FIG. 17, it is preferable to compress the biasing portion 83 to about half its original size. This makes it possible to more reliably allow the contact portion 62 to move up and down thereafter.

[0057] According to this configuration, the shape of the object W can be detected based on the displacement of the contact portion 62 relative to the robot arm 22. Therefore, for example, the shape of the object W can be detected more easily than in the first embodiment described above. Specifically, in the first embodiment described above, it is necessary to move the contact portion 62 in the direction along the arrow G1 as well as in the direction along the arrow G2 while keeping the pressing force F constant, so that the control of the robot arm 22 tends to be complicated and it is difficult to increase the moving speed in the direction along the arrow G1. In addition, since the shape of the object W is detected from the rotation amount of each joint J1 to J6, the calculation tends to be complicated. In contrast, according to this embodiment, it is sufficient to simply move the contact portion 62 in the direction along the arrow G1, so that the control of the robot arm 22 is simplified and the moving speed in the direction along the arrow G1 is easily increased. In addition, since the shape of the object W can be detected based only on the detection result by the displacement amount detection unit 84, the calculation is relatively simple. Therefore, the shape of the object W can be easily detected.

[0058] In this embodiment, the force sensor 7 can be omitted. In addition, when the force sensor 7 is provided, the detected shape of the target object W may be corrected based on the force received by the force sensor 7 during the above-mentioned work.

[0059] As described above, the robot system 1 of the present embodiment has a support mechanism 8 that is disposed between the contact portion 62 and the robot arm 22, allows displacement of the contact portion 62 relative to the robot arm 22, and has a displacement amount detection unit 84 that detects the amount of displacement of the contact portion 62 relative to the robot arm 22. With this configuration, the shape of the object W can be detected based on the amount of displacement of the contact portion 62 relative to the robot arm 22. Therefore, the shape of the object W can be easily detected.

[0060] The second embodiment as described above can also achieve the same effects as the first embodiment described above.

[0061] <Third embodiment> FIG. 19 is a diagram for explaining a printing method using a robot system according to the third embodiment.

[0062] This embodiment is similar to the first embodiment described above, except for the printing method. In the following description, the differences between this embodiment and the first embodiment will be mainly described, and the description of the similarities will be omitted. In the drawings of this embodiment, the same reference numerals are used for the same configurations as the above-mentioned embodiment.

[0063] In the first embodiment described above, the separation distance detection step S1 is performed prior to the printing step S2, but in this embodiment, the separation distance detection step S1 is performed during the printing step S2. That is, the printing operation is performed while detecting the separation distance D. According to this method, the time required for the separation distance detection step S1 can be omitted, and the printing operation can be made more efficient.

[0064] 19, in printing step S2 of this embodiment, the control device 9 first moves the robot arm 22 to bring the contact portion 62 of the contact jig 6 into contact with the surface of the target object W. In this state, the contact portion 62 is located forward of the print head 3 in the movement direction of the print head 3. Then, similar to the first embodiment described above, the control device 9 moves the robot arm 22 along the arrow G1 in a manner of rolling the contact portion 62 over the target object W, while moving the robot arm 22 up and down along the arrow G2 so that the pressing force F is constant, and ejects ink I from each nozzle 31 based on a preset ink ejection timing.

[0065] At this time, the control device 9 detects shape data of the object W on the forward side in the movement direction of the print head 3 based on the up and down movement of the tip of the robot arm 22, calculates the separation distance D between each nozzle 31 and the object W based on the detected shape of the object W, corrects the ink ejection timing based on the calculated separation distance D, and ejects ink I from each nozzle 31 based on the corrected ink ejection timing. According to this method, the ink ejection timing can be corrected according to the separation distance D while printing is being performed. Therefore, high-quality printing with little misalignment, blurring, distortion, etc. can be performed on the object W even without correcting the ink ejection timing in advance.

[0066] In the printing method described above, as described above, the contact portion 62 is brought into contact with the object W in front of the print head 3, and the printing operation is performed while detecting the shape of the object W. According to such a method, the efficiency of the printing operation can be improved.

[0067] As described above, in the robot system 1, during printing, the contact portion 62 is located forward of the print head 3 in the movement direction. With this configuration, the printing can be performed while detecting the shape of the target object W. This makes it possible to improve the efficiency of the printing.

[0068] The third embodiment as described above can also achieve the same effects as the first embodiment described above.

[0069] Although the printing method and robot system of the present invention have been described above with reference to the illustrated embodiment, the present invention is not limited to this, and the configuration and steps of each part can be replaced with any configuration or step having a similar function. In addition, any other configuration or step may be added to the present invention. In addition, each embodiment may be appropriately combined. [Explanation of symbols]

[0070] 1...robot system, 10...robot, 2...robot body, 21...base, 22...robot arm, 221...arm, 222...arm, 223...arm, 224...arm, 225...arm, 226...arm, 3...print head, 31...nozzle, 31a...nozzle, 31b...nozzle, 31c...nozzle, 31d...nozzle, 31e...nozzle, 4...moving stage, 40...base, 400...piezoelectric actuator, 41...first stage, 42...second stage, 43...base, 45...first stage drive unit, 46...second stage drive unit, 5...vibration meter, 6...contact jig, 61...base, 62...contact portion, 7...force sensor, 8...support mechanism, 81...fixed portion, 82...movable portion, 83...urging portion, 84...displacement amount detection portion, 841...light emitting / receiving element, 842...scale, 9...control device, A...first direction, B...second direction, D...separation distance, D0...ideal distance, D3...separation distance, D6...separation distance, F...pressure, G1...arrow, G2...arrow, I...ink, J1...joint, J2...joint, J3...joint, J4...joint, J5...joint, J6...joint, JJ...rotation axis, P...image, Q...printing trajectory, S1...separation distance detection step, S2...printing step, T...target impact position, W...object, W0...object, d...distance

Claims

1. A printing method using a robot equipped with a print head, performing a printing operation on an object by ejecting ink from the print head while moving the object and the print head relatively, comprising: the robot has a contact portion that contacts the object, Using the robot, the contact portion is moved relative to the object while being brought into contact with the object; Detecting a shape of the object from a trajectory of the robot during the movement; A printing method, comprising: performing the printing job based on the shape of the object.

2. the print head has nozzles for ejecting the ink, The printing method according to claim 1 , wherein, in the printing operation, when a distance between the nozzle and the target object exceeds a threshold value, the ink is not ejected from the nozzle.

3. The printing method of claim 2 , wherein the object is a three-dimensional shape.

4. The printing method according to claim 2 , wherein the nozzles are arranged in a plurality of rows in a direction intersecting the direction of the movement.

5. The printing method according to claim 1 , wherein the contact portion is brought into contact with the object in front of the print head, and the printing operation is performed while detecting the shape of the object.

6. a robot having a robot arm and a print head and a contact unit disposed at a tip of the robot arm via a base; A control device for controlling the driving of the robot, The control device uses the robot arm to move the contact portion relative to the object while bringing the contact portion into contact with the object; Detecting a shape of the object from a trajectory of the tip of the robot arm during the movement; A robot system that performs a printing operation on an object based on the shape of the object.

7. the print head has nozzles for ejecting the ink, The robot system according to claim 6 , wherein the control device does not eject the ink from the nozzle when a distance between the nozzle and the object exceeds a threshold value.

8. The robot system according to claim 6 , wherein the robot comprises a force sensor disposed between the base and the robot arm.

9. The robot system according to claim 6 , wherein the contact portion is a rotating body that moves relative to the object while rotating.

10. The robot system according to claim 6 , wherein, during the printing operation, the contact portion is located forward of the print head in a movement direction.

11. A contact portion is disposed between the contact portion and the robot arm. allowing the contact portion to be displaced relative to the robot arm; The robot system according to claim 6 , further comprising a support mechanism having a displacement amount detection unit that detects the amount of displacement of the contact portion relative to the robot arm.

Images