Printing method and robot system

Abstract

To provide a printing method and a robot system which can suppress lowering of a printing quality.SOLUTION: A printing method for performing printing on a printing object using a printing head provided on a first robot performs the printing by relatively moving the printing head and the printing object, while vibrating at least one of the printing head and the printing object, so that relative vibration between the printing head and the printing object is reduced. The printing method detects vibration of any one of the printing head and the printing object, and performs the printing while vibrating at least one of the printing head and the printing object.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The robot system described in Patent Document 1 is equipped with a print head attached to its tip. In this robot system, the robot is operated to move the print head along a print trajectory while ejecting ink from the print head toward the print object, thereby printing on the print object. [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] However, in the robot system of Patent Document 1, if there is relative vibration between the print head and the object to be printed, that is, if there is relative displacement between the print head and the object to be printed other than the movement of the print head along the printing path, the print will be blurred even if the print head is moved along the printing path, resulting in reduced quality. [Means for solving the problem]

[0005] The printing method of the present invention is a printing method for printing on a printing object using a print head provided in a first robot, The printing is performed by moving the print head and the print object relative to each other while vibrating at least one of the print head and the print object so as to reduce the relative vibration between the print head and the print object.

[0006] The robot system of the present invention includes a first robot having a print head that prints on a print object, The printing is performed by moving the print head and the print object relative to each other while vibrating at least one of the print head and the print object so as to reduce the relative vibration between the print head and the print 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] FIG. 2 is a schematic diagram showing a printing operation. [Diagram 3] FIG. 2 is a plan view showing a first vibration generating device. [Figure 4] FIG. 2 is a plan view showing a detection element. [Diagram 5] FIG. 4 is a plan view showing a second vibration generating device. [Figure 6] FIG. 1 is a diagram illustrating how vibration is transmitted. [Figure 7] FIG. 11 is an overall view of a robot system according to a third embodiment. [Figure 8] FIG. 13 is an overall view of a robot system according to a fourth 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 schematic diagram showing a printing operation. Fig. 3 is a plan view showing a first vibration generator. Fig. 4 is a plan view showing a detection element. Fig. 5 is a plan view showing a second vibration generator. Fig. 6 is a diagram showing how vibrations are transmitted.

[0010] The robot system 1 shown in FIG. 1 includes a holding device 2 that holds a print target W, a first robot 3 that prints on the print target W held by the holding device 2, and a control device 9 that controls the driving of the holding device 2 and the first robot 3. In the illustrated configuration, the holding device 2 and the first robot 3 are both fixed to a mounting table 10, but this is not limited thereto, and they may be fixed to different mounting tables. At least one of the holding device 2 and the first robot 3 may be fixed to a location other than the mounting table, such as a floor or a wall. At least one of the first robot 3 and the holding device 2 may be configured to be unfixed and self-propelled. In addition, the print target W is bowl-shaped with a curved printing surface, but the shape of the print target W is not particularly limited. Below, each part constituting the robot system 1 will be described in order.

[0011] <First Robot 3> The first robot 3 has a robot body 30, a print head 39 attached to the tip of the robot body 30, a first vibration generator 4 arranged between the robot body 30 and the print head 39, and a first vibrometer 5 that detects vibrations of the print head 39. For ease of explanation, the robot coordinate system set on the base 31 of the robot body 30 is indicated by the X-, Y-, and Z-axes, and the tool coordinate system set at the tip of the robot arm 32 is indicated by the x-, y-, and z-axes. The tool coordinate system can be converted into the robot coordinate system based on the position and orientation of the print head 39 obtained from the output of the encoders provided in each of the joints J1 to J6.

[0012] The robot body 30 is a six-axis vertical articulated robot having six drive axes, and includes a base 31 fixed to the mounting table 10 and a robot arm 32 rotatably connected to the base 31. The robot arm 32 includes six arms 321, 322, 323, 324, 325, and 326 rotatably connected in this order from the base 31 side, and includes six joints J1 to J6. Among these, the joints J2, J3, and J5 are bending joints, and the joints J1, J4, and J6 are torsion joints. A motor and an encoder are installed in each of the joints J1, J2, J3, J4, J5, and J6, and the motor is driven by servo control that feeds back the output of the encoder.

[0013] However, there is no particular limitation on the configuration of the robot body 30. For example, the number of arms provided in the robot arm 32 is not limited to six. Furthermore, the robot body 30 may be a dual-arm robot, a horizontally articulated robot (SCARA robot), or the like.

[0014] The print head 39 is disposed at the tip of the robot arm 32, i.e., at the arm 326. The print head 39 is not particularly limited, but an inkjet head is used in this embodiment. The inkjet head has an ink chamber (not shown), a vibration plate disposed on the wall of the ink chamber, and ink ejection holes connected to the ink chamber, and ink in the ink chamber is ejected from the ink ejection holes by vibration of the vibration plate. Then, as shown in FIG. 2, printing is performed by ejecting ink from the print head 39 onto the surface to be printed while moving the print head 39 by the robot arm 32 at a predetermined printing trajectory Q and speed relative to the print target W.

[0015] The first vibration generator 4 is disposed between the arm 326 and the print head 39. The first vibration generator 4 is a device that applies vibrations to the print head 39. As shown in FIG. 3, the first vibration generator 4 has a base 40 supported by the arm 326, a first stage 41 that moves in the x-axis direction relative to the base 40, a second stage 42 that moves in the y-axis direction relative to the first stage 41, a third stage 43 that moves in the z-axis direction relative to the second stage 42, and a fourth stage 44 that rotates around the z-axis relative to the third stage 43, and the print head 39 is disposed on the fourth stage 44.

[0016] Therefore, when the first stage 41 moves in the x-axis direction, the print head 39 vibrates in the x-axis direction, when the second stage 42 moves in the y-axis direction, the print head 39 vibrates in the y-axis direction, when the third stage 43 moves in the z-axis direction, the print head 39 vibrates in the z-axis direction, and when the fourth stage 44 rotates around the z-axis, the print head 39 vibrates around the z-axis. By appropriately combining these four vibrations, the print head 39 can be vibrated in various magnitudes and directions.

[0017] In addition, the first vibration generating device 4 has a first stage driving unit 45 that moves the first stage 41 relative to the base 40, a second stage driving unit 46 that moves the second stage 42 relative to the first stage 41, a third stage driving unit 47 that moves the third stage 43 relative to the second stage 42, and a fourth stage driving unit 48 that moves the fourth stage 44 relative to the third stage 43.

[0018] The first, second, third and fourth stage driving units 45, 46, 47 and 48 each include a piezoelectric actuator 400 that is driven by utilizing the expansion and contraction of a piezoelectric element caused by energization, and transmits the vibration of the piezoelectric actuator 400 to the first, second, third and fourth stages 41, 42, 43 and 44 to move them. By using the piezoelectric actuator 400, the movement amount and movement speed of the first, second, third and fourth stage driving units 45, 46, 47 and 48 can be finely and highly accurately controlled, and the movement direction can be quickly switched. In addition, the first vibration generating device 4 can be made smaller and lighter. Therefore, an increase in the weight of the tip of the robot body 30 can be suppressed, and a decrease in the drive characteristics such as the responsiveness and vibration damping of the robot body 30 can be effectively suppressed.

[0019] Although the first vibration generator 4 has been described above, the configuration of the first vibration generator 4 is not particularly limited. For example, the number of stages that move relative to the base 40 is not particularly limited, and may be three or less, or may be five or more. In addition, the first, second, third, and fourth stage driving units 45, 46, 47, and 48 may be configured to use a driving source other than the piezoelectric actuator 400, such as a motor that rotates when energized. In addition, the location of the first vibration generator 4 is not particularly limited as long as it can vibrate the print head 39, and may be, for example, located between the robot body 30 and the mounting table 10.

[0020] The first vibration meter 5 is disposed on the print head 39 and detects vibrations of the print head 39. Note that the "vibration" refers to displacements other than those along the print trajectory Q, which will be described later. Such a first vibration meter 5 is a three-axis acceleration sensor, and as shown in Figure 3, has a rectangular parallelepiped housing 51, and an acceleration sensor unit 52 and a control IC 53 housed in the housing 51.

[0021] The dimensions of the housing 51 are not particularly limited, but for example, the width x depth x height are preferably 62.4 mm x 46.2 mm x 36.2 mm or less. Furthermore, the weight of the housing 51 is not particularly limited, but for example, it is preferably 100 g or less. This makes the first vibration meter 5 sufficiently small and lightweight, and increases the freedom of movement of the arrangement of the first vibration meter 5. Furthermore, an increase in the weight of the tip of the robot body 30 can be suppressed, and a decrease in the responsiveness, vibration damping, etc. of the robot body 30 can be effectively suppressed.

[0022] The acceleration sensor unit 52 also has an acceleration sensor 52x that detects acceleration in the x-axis direction, an acceleration sensor 52y that detects acceleration in the y-axis direction, and an acceleration sensor 52z that detects acceleration in the z-axis direction. Each of the acceleration sensors 52x, 52y, and 52z has a detection element 54 shown in FIG.

[0023] The detection element 54 has a substrate structure 541, a quartz crystal vibration element 542 fixed to the surface of the substrate structure 541, and a weight 543. The substrate structure 541 is formed from a quartz crystal substrate, and has a base 541a and a movable part 541b extending from the base 541a. The weight 543 is disposed at the tip of the movable part 541b. The quartz crystal vibration element 542 is a double-tuning-fork type quartz crystal vibration element formed from a quartz crystal substrate, and one end is fixed to the base 541a and the other end is fixed to the movable part 541b. Although not shown, a pair of excitation electrodes is disposed on each of the vibration beams 542a, 542b of the quartz crystal vibration element 542, and when an AC voltage is applied between these excitation electrodes, the two vibration beams 542a, 542b flexurally vibrate so as to repeatedly approach and move away from each other.

[0024] When acceleration in the thickness direction is applied to such detection element 54, movable part 541b is deflected, which applies tensile or compressive stress to quartz vibration element 542, and the resonant frequency of quartz vibration element 542 changes depending on the magnitude of the applied stress. Therefore, acceleration can be detected based on the change in the resonant frequency of quartz vibration element 542.

[0025] In the acceleration sensor 52x, the thickness direction of the detection element 54 coincides with the x-axis direction, in the acceleration sensor 52y, the thickness direction of the detection element 54 coincides with the y-axis direction, and in the acceleration sensor 52z, the thickness direction of the detection element 54 coincides with the z-axis direction. Therefore, the acceleration sensors 52x, 52y, and 52z can detect acceleration in the x-axis, y-axis, and z-axis directions, respectively. Here, the crystal vibration element 542 has excellent frequency-temperature characteristics compared to elements formed from other piezoelectric materials and elements formed from silicon, which is also commonly used as a material for sensor elements like crystal, and therefore can perform temperature compensation with high accuracy. In addition, since the circuit measures frequency changes, analog elements can be eliminated and noise is low. Therefore, the vibration of the print head 39 can be detected with high accuracy.

[0026] The control IC 53 is, for example, an MCU (Micro Controller Unit), and includes a control circuit for controlling the driving of the acceleration sensor unit 52, and an interface circuit for communicating with the outside. Among them, the control circuit drives the acceleration sensors 52x, 52y, and 52z, and detects the acceleration in each axial direction based on the resonance frequency of the crystal vibration element 542 included in the acceleration sensors 52x, 52y, and 52z. Meanwhile, the interface circuit transmits and receives signals to and from the control device 9, receives commands from the control device 9, and outputs detected acceleration information to the control device 9. Here, the control IC 53 transmits and receives signals to and from the control device 9 wirelessly. This eliminates the need for wiring signal lines, making it easier to install the first vibration meter 5 and increasing the freedom of installation location. The wireless communication standard is not particularly limited, and Wi-Fi, Bluetooth (registered trademark), etc. can be used, but Bluetooth is used in this embodiment. This allows for power saving.

[0027] The maximum sampling rate of the first vibrometer 5 is not particularly limited, but is preferably 1000 Hz or more. This allows each acceleration to be acquired at a sufficiently high rate, and the vibration of the print head 39 can be detected with high accuracy. The noise density of the first vibrometer 5 is not particularly limited, but is preferably 0.2 μG / √Hz or less. This allows noise to be sufficiently suppressed, and the vibration of the print head 39, particularly low-frequency vibration, can be detected with high accuracy. In particular, since the vibration generated in the print head 39 during printing is about several Hz to several tens of Hz, this characteristic is more prominent. Note that the noise density is the average value of the noise density at 0.5 Hz to 6 Hz at 25° C. expressed as a typical value. The maximum measurement frequency of the first vibrometer 5 is preferably 460 Hz or more. This allows the frequency band of vibrations that may occur in the print head 39 to be sufficiently covered, and the vibration of the print head 39 can be detected with high accuracy.

[0028] The first vibration meter 5 has been described above, but the configuration of the first vibration meter 5 is not particularly limited as long as it can detect the vibration of the print head 39. For example, the detection element 54 of the acceleration sensors 52x, 52y, and 52z may be a silicon MEMS. The silicon MEMS may be configured to include, for example, a comb-shaped fixed electrode and a movable electrode that are arranged in mesh with each other, and detect the acceleration based on a change in electrostatic capacitance between the fixed electrode and the movable electrode that occurs when the movable electrode is displaced relative to the fixed electrode due to the received acceleration. In addition, the location of the first vibration meter 5 is not particularly limited as long as it can detect the vibration of the print head 39, and may be, for example, located on the fourth stage 44 of the first vibration generator 4.

[0029] <Holding device 2> As shown in FIG. 1, the holding device 2 has a holding section 20 that holds the printing object W, a second vibration generating device 6 that vibrates the holding section 20, and a second vibration meter 7 that detects vibrations of the printing object W.

[0030] The holding unit 20 has a placement unit 21 on which the printing target W is placed, and a pair of claws 22, 23 that clamp and secure the printing target W. However, the configuration of the holding unit 20 is not particularly limited as long as it can hold the printing target W, and can be designed appropriately depending on the shape of the printing target W, the position of the surface to be printed, etc.

[0031] The second vibration generator 6 is disposed between the holder 20 and the mounting table 10. The second vibration generator 6 is a device that applies vibration to the print target W. The second vibration generator 6 has the same configuration as the first vibration generator 4, and as shown in FIG. 5, includes a base 60 fixed to the mounting table 10, a first stage 61 that moves in the X-axis direction relative to the base 60, a second stage 62 that moves in the Y-axis direction relative to the first stage 61, a third stage 63 that moves in the Z-axis direction relative to the second stage 62, a fourth stage 64 that rotates around the Z-axis relative to the third stage 63, a first stage drive unit 65 that moves the first stage 61 relative to the base 60, a second stage drive unit 66 that moves the second stage 62 relative to the first stage 61, a third stage drive unit 67 that moves the third stage 63 relative to the second stage 62, and a fourth stage drive unit 68 that moves the fourth stage 64 relative to the third stage 63. The holder 20 is disposed on the fourth stage 64. Each of these components has the same configuration as the first vibration generator 4 described above, and therefore the description thereof will be omitted.

[0032] Although the second vibration generator 6 has been described above, the configuration of the second vibration generator 6 is not particularly limited. Furthermore, the second vibration generator 6 may have a different configuration from the first vibration generator 4. Furthermore, the arrangement of the second vibration generator 6 is not particularly limited as long as it can vibrate the printing target W.

[0033] As shown in FIG. 2, the second vibrometer 7 is disposed in the holder 20 and detects vibrations of the printing target W. The second vibrometer 7 is similar to the first vibrometer 5 described above. That is, the second vibrometer 7 is a three-axis acceleration sensor and includes a rectangular parallelepiped housing 71, and an acceleration sensor unit 72 and a control IC 73 housed in the housing 71. The acceleration sensor unit 72 includes an acceleration sensor 72x that detects acceleration in the X-axis direction, an acceleration sensor 72y that detects acceleration in the Y-axis direction, and an acceleration sensor 72z that detects acceleration in the Z-axis direction. Note that these components have the same configuration as the first vibrometer 5 described above, and therefore their description will be omitted.

[0034] The second vibrometer 7 has been described above. However, the configuration of the second vibrometer 7 is not particularly limited as long as it can detect the vibration of the printing object W. The second vibrometer 7 may have a different configuration from the first vibrometer 5. The arrangement of the second vibrometer 7 is not particularly limited as long as it can detect the vibration of the printing object W, and may be arranged directly on the printing object W, for example. However, if the second vibrometer 7 is arranged directly on the printing object W, the vibration of the printing object W can be detected more accurately, but it is necessary to replace the second vibrometer 7 and perform calibration every time a new printing object W is set on the holding unit 20 after printing, which deteriorates workability. Therefore, in this embodiment, the second vibrometer 7 is arranged on the holding unit 20 to achieve both workability and accuracy.

[0035] <Control device 9> The control device 9 controls the driving of the first robot 3 and the holding device 2. The control device 9 is composed of, for example, 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.

[0036] The above describes the configuration of the robot system 1. Next, a printing method for printing on a print target W using such a robot system 1 will be described.

[0037] ≪Printing method≫ As described above, printing using the robot system 1 is performed by discharging ink from the print head 39 onto the printing surface of the printing object W while moving the print head 39 along the printing surface of the printing object W at a predetermined printing trajectory Q and speed. However, if relative vibration occurs between the print head 39 and the printing object W during printing, that is, if a displacement other than the movement of the print head 39 along the printing trajectory Q occurs between the print head 39 and the printing object W, the actual trajectory of the print head 39 relative to the printing object W deviates from the printing trajectory Q, and the printing quality deteriorates. Note that the relative vibration between the print head 39 and the printing object W will be simply referred to as "relative vibration" below.

[0038] Relative vibrations are generated, for example, as follows. As shown in Fig. 6, driving of the robot body 30 generates vibrations V1 in the print head 39. Vibrations V1 are then transmitted to the mounting table 10 via the robot body 30, generating vibrations V2 in the mounting table 10, and vibrations V2 are further transmitted to the holding device 2, generating vibrations V3 in the holding device 2. Vibrations V2 and V3 are then superimposed to generate vibrations V4 in the print target W. In this way, different vibrations V1 and V4 are generated between the print head 39 and the print target W, generating relative vibrations.

[0039] Therefore, in the printing method using the robot system 1, the relative vibration is detected, and printing is performed while vibrating at least one of the robot arm 32, the print head 39, and the print object W so that the detected relative vibration is reduced, and preferably eliminated. This reduces the deviation between the actual trajectory of the print head 39 relative to the print object W and the print trajectory Q, compared to when vibration is not performed, and printing on the print object W can be performed with high accuracy. Therefore, deterioration of print quality can be effectively suppressed. Note that "detecting the relative vibration" means determining the direction and magnitude of the relative vibration.

[0040] The control device 9 determines the relative vibration from the difference between the vibration V1 of the print head 39 and the vibration V4 of the print target W. Specifically, in the robot system 1, the first vibrometer 5 is used to determine the vibration V1 of the print head 39, the second vibrometer 7 is used to determine the vibration V4 of the print target W, and the relative vibration is determined from the difference between the determined vibrations V1 and V4. This method makes it possible to easily detect the relative vibration. In particular, since the first vibrometer 5 is disposed on the print head 39 and the second vibrometer 7 is disposed on the holder 20, the relative vibration can be detected with high accuracy. However, the method of detecting the relative vibration is not particularly limited.

[0041] Furthermore, the control device 9 drives at least one of the robot arm 32, the first vibration generator 4, and the second vibration generator 6 to apply a countervailing vibration to at least one of the print head 39 and the print target W, which reduces or preferably eliminates the relative vibration. The "countervailing vibration" is not particularly limited as long as it can cancel out at least a part of the relative vibration, but it is preferable that it is a vibration of opposite phase to the relative vibration. In theory, this cancels out the entire relative vibration, and the relative vibration disappears. Therefore, the deterioration of print quality can be more effectively suppressed.

[0042] Methods for applying the offsetting vibration include (a) a method for applying the offsetting vibration to the print head 39 by driving the robot arm 32, (b) a method for applying the offsetting vibration to the print head 39 by driving the first vibration generator 4, (c) a method for applying the offsetting vibration to the print target W by driving the second vibration generator 6, (d) a method for applying the offsetting vibration to the print head 39 by driving the robot arm 32 and the first vibration generator 4, (e) a method for applying the offsetting vibration between the print head 39 and the print target W by driving the robot arm 32 and the second vibration generator 6, (f) a method for applying the offsetting vibration between the print head 39 and the print target W by driving the first vibration generator 4 and the second vibration generator 6, and (g) a method for applying the offsetting vibration between the print head 39 and the print target W by driving all of the robot arm 32, the first vibration generator 4, and the second vibration generator 6. One of these methods can be selected and executed. In the above cases (e) to (g), the print head 39 and the print object W may be vibrated so that the combined vibration of the print head 39 and the print object W cancels out each other.

[0043] According to this method, at least a part of the relative vibration is eliminated by the countervailing vibration, and the relative vibration is smaller than when the countervailing vibration is not applied. As a result, the deviation between the actual trajectory of the print head 39 relative to the print object W and the print trajectory Q is reduced, and the deterioration of print quality can be effectively suppressed. In particular, when only the print head 39 is subjected to countervailing vibration as in (a), (b), and (d), the print object W can be stopped, so that the deviation or separation of the print object W relative to the holding device 2 can be suppressed. On the other hand, when only the print object W is vibrated as in (c), it is not necessary to cause the print head 39 to perform any movement other than the movement along the print trajectory Q, so that the drive of the first robot 3 becomes smooth. Therefore, in both cases, the deterioration of print quality can be effectively suppressed.

[0044] Furthermore, as in (d), (e), and (g), when applying cancelling vibrations using two or more of the robot arm 32, the first vibration generator 4, and the second vibration generator 6, including the robot arm 32, it is preferable to do so as follows. The relative vibrations include low-frequency relative vibrations below a predetermined frequency and high-frequency relative vibrations above a predetermined frequency. The predetermined frequency is not particularly limited, but is, for example, about 10 Hz. Furthermore, the robot arm 32 is heavier than the first and second vibration generators 4 and 6, and therefore has poor responsiveness.

[0045] Therefore, in (d), the robot arm 32 is driven to apply low-frequency offset vibration to the print head 39 to offset the low-frequency relative vibration, and the first vibration generator 4 is driven to apply high-frequency offset vibration to the print head 39 to offset the high-frequency relative vibration. The combination of the low-frequency offset vibration and the high-frequency offset vibration results in offsetting vibration, so the offsetting vibration is reduced overall. Similarly, in (e), the robot arm 32 is driven to apply low-frequency offset vibration to the print head 39, and the second vibration generator 6 is driven to apply high-frequency offset vibration to the print target W. Also, in (g), the robot arm 32 is driven to apply low-frequency offset vibration to the print head 39, and the first and second vibration generators 4 and 6 are driven to apply high-frequency offset vibration between the print head 39 and the print target W. In this way, by sharing the frequency band of the cancelling vibrations generated by the robot arm 32 and the first and second vibration generators 4, 6, it is possible to apply cancelling vibrations with high precision without placing excessive strain on each part.

[0046] Also, as in (d) to (g), when applying the countervailing vibration using two or more of the robot arm 32, the first vibration generator 4, and the second vibration generator 6, the vibration direction may be shared. To explain (f) as a representative example, for example, the first vibration generator 4 may be driven to apply a first countervailing vibration that countervails the vibration components in the X-axis and Y-axis directions of the countervailing vibration to the print head 39, and the second vibration generator 6 may be driven to apply a second countervailing vibration that countervails the vibration component in the Z-axis direction of the countervailing vibration to the print target W. This method is effective when the vibration components that can be generated by the first and second vibration generators 4 and 6 are different and neither one can generate the countervailing vibration by itself. Also, for example, the magnitude of the vibration may be shared. Similarly, to explain (f) as a representative example, a first offsetting vibration having half the magnitude of the relative vibration may be applied to the print head 39 using the first vibration generator 4, and a second offsetting vibration having the remaining half the magnitude of the relative vibration may be applied to the print target W using the second vibration generator 6. This method is effective when the outputs of the first and second vibration generators 4, 6 are insufficient and neither of them can generate offsetting vibrations by itself.

[0047] Next, the timing of detecting the relative vibration will be described. For example, the relative vibration may be detected by performing a test run of the print head 39 before printing. Specifically, before printing, the print head 39 is moved at the same print trajectory Q and speed as in actual printing without ejecting ink from the print head 39, the relative vibration at that time is detected, and the offset vibration is determined based on the detected relative vibration. Then, actual printing is performed while applying the determined offset vibration between the print head 39 and the print target W by any of the above-mentioned methods. In other words, printing is performed on the print target W by moving the print head 39 at a predetermined speed along the print trajectory Q while ejecting ink from the print head 39 while applying the offset vibration between the print head 39 and the print target W. According to such a method, the offset vibration can be determined in advance, which makes it easier to control the robot system 1.

[0048] Relative vibration may also be detected during printing. Specifically, the print head 39 starts moving at a predetermined speed along the print trajectory Q for printing and starts detecting relative vibration, and each time the latest relative vibration is detected, a counterbalancing vibration to counterbalance it is determined, and the determined counterbalancing vibration is applied between the print head 39 and the print target W by any of the methods described above. In other words, the relative vibration is detected in real time during printing, and the result is fed back to the counterbalancing vibration. In this way, the method of detecting relative vibration while printing eliminates the need for a trial run in advance to detect the relative vibration, improving the efficiency of the printing process.

[0049] The robot system 1 has been described above. As described above, the printing method performed using such a robot system 1 is a printing method in which printing is performed on the print target W using the print head 39 provided in the first robot 3, and printing is performed by moving the print head 39 and the print target W relatively while vibrating at least one of the print head 39 and the print target W so as to reduce the relative vibration between the print head 39 and the print target W. According to this printing method, the relative vibration between the print head 39 and the print target W is suppressed, so that the deviation between the actual trajectory of the print head 39 with respect to the print target W and the print trajectory Q is reduced, and printing on the print target W can be performed with high accuracy. Therefore, the deterioration of print quality can be effectively suppressed.

[0050] As described above, the printing method detects vibrations of either the print head 39 or the print object W, and performs printing while vibrating at least one of the print head 39 and the print object W. This makes it possible to more reliably apply vibrations to the print head 39 and the print object W that can reduce the relative vibrations.

[0051] As described above, in the printing method, the relative vibration is detected by separately detecting the vibration of the print head 39 and the vibration of the print target W. This makes it possible to easily detect the relative vibration.

[0052] As described above, the printing method includes the first vibration meter 5 that detects the vibration of the print head 39 and the second vibration meter 7 that detects the vibration of the print object W. This makes it possible to accurately detect the vibration of the print head 39 and the vibration of the print object W, respectively, and therefore to accurately detect the relative vibration.

[0053] As described above, in the printing method, the first vibrometer 5 includes the crystal vibration element 542. Although not shown, the second vibrometer 7 also includes a crystal vibration element similar to the crystal vibration element 542. This makes it possible to detect the vibrations of the print head 39 and the printing target W with high accuracy.

[0054] As described above, in the printing method, the relative vibration may be reduced by vibrating only the print head 39 out of the print head 39 and the print target W. According to such a method, the print target W can be kept stationary, so that the displacement of the print target W can be suppressed.

[0055] Furthermore, as described above, in the printing method, the relative vibration may be reduced by vibrating only the print object W out of the print head 39 and the print object W. According to such a method, the print head 39 can be kept stationary during the vibration control operation, so that the drive of the first robot 3 becomes smoother.

[0056] As described above, the printing method performs printing while detecting the relative vibration, which allows the relative vibration to be detected in real time during printing and the result to be fed back, thereby more reliably reducing the relative vibration during printing.

[0057] As described above, the printing method may include detecting the relative vibration and then printing. According to this method, the relative vibration is detected only once before printing, which makes control easier.

[0058] As described above, the robot system 1 has a first robot 3 equipped with a print head 39 that prints on a print target W, and performs printing by moving the print head 39 and the print target W relatively while vibrating at least one of the print head 39 and the print target W so as to reduce the relative vibration between the print head 39 and the print target W. With this configuration, the relative vibration between the print head 39 and the print target W is suppressed, so that the deviation between the actual trajectory of the print head 39 with respect to the print target W and the print trajectory Q is reduced, and printing on the print target W can be performed with high accuracy. Therefore, deterioration of print quality can be effectively suppressed.

[0059] <Second embodiment> The robot system 1 according to this embodiment is similar to the robot system 1 according to the first embodiment described above, except for the printing method. In the following description, the robot system 1 according to this embodiment will be described focusing on the differences from the first embodiment described above, and a description of the similarities will be omitted.

[0060] In the printing method of the present embodiment, the relative vibration is not detected, the vibration of the print head 39 is offset by driving the first vibration generator 4, and the vibration of the print target W is offset by driving the second vibration generator 6. Specifically, the control device 9 detects the print head vibration, which is the vibration of the print head 39, using the first vibration meter 5, and applies the print head offsetting vibration to the print head 39 to offset the print head vibration using the first vibration generator 4. This makes it possible to reduce the vibration of the print head 39. Similarly, the control device 9 detects the print target vibration, which is the vibration of the print target W, using the second vibration meter 7, and applies the print target offsetting vibration to the print target W to offset the print target vibration using the second vibration generator 6. This makes it possible to reduce the vibration of the print target W. In this way, the relative vibration is reduced by reducing the vibration of the print head 39 and the print target W, respectively. Alternatively, the vibration of one of the print head 39 and the print target W may be detected, and the offsetting vibration to offset the detected vibration may be applied to the other. This reduces the relative vibration. According to this method, the relative vibration can be more reliably reduced without detecting the relative vibration.

[0061] The second embodiment as described above can also achieve the same effects as the first embodiment.

[0062] <Third embodiment> FIG. 7 is an overall view of a robot system according to the third embodiment.

[0063] The robot system 1 according to this embodiment is similar to the robot system 1 according to the first embodiment, except that first and second vibration damping members 38, 28 are provided instead of the first and second vibration generators 4, 6. In the following description, the robot system 1 according to this embodiment will be described with a focus on the differences from the first embodiment, and a description of the similarities will be omitted. In the drawings of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0064] As shown in FIG. 7, in the robot system 1 of this embodiment, the first vibration generator 4 is omitted from the first robot 3, and instead, a first vibration damping member 38 is arranged between the arm 326 and the print head 39. In addition, the second vibration generator 6 is omitted from the holding device 2, and instead, a second vibration damping member 28 is arranged between the mounting table 10 and the holding unit 20. The first and second vibration damping members 38, 28 are made of, for example, a rubber material, and can absorb at least a part, preferably all, of the high-frequency relative vibration included in the relative vibration. The low-frequency relative vibration included in the relative vibration that cannot be absorbed by the first and second vibration damping members 38, 28 is offset by applying a low-frequency offsetting vibration to the print head 39 using the robot arm 32. According to such a configuration, for example, the configuration is simpler than the first embodiment described above, and therefore the control is easier.

[0065] The third embodiment as described above can also achieve the same effects as the first embodiment described above.

[0066] <Fourth embodiment> FIG. 8 is an overall view of a robot system according to the fourth embodiment.

[0067] The robot system 1 according to this embodiment is similar to the robot system 1 according to the first embodiment, except for the configuration of the holding device 2. In the following description, the robot system 1 according to this embodiment will be described with a focus on the differences from the first embodiment, and a description of the similarities will be omitted. In the drawings of this embodiment, the same reference numerals are used for the same configurations as those in the above-mentioned embodiment.

[0068] 8, the holding device 2 is a second robot 2A. The second robot 2A has a robot body 80, a holding unit 20 arranged at the tip of the robot body 80, a second vibration generating device 6 arranged between the robot body 80 and the holding unit 20, and a second vibrometer 7 arranged on the holding unit 20.

[0069] The robot body 80 is a six-axis vertical articulated robot, and has the same configuration as the robot body 30 of the first robot 3. That is, the robot body 80 has a base 81 fixed to the mounting table 10, and a robot arm 82 rotatably connected to the base 81. The holding unit 20 is disposed at the tip of the robot arm 82, the second vibration generator 6 is disposed between the robot arm 82 and the holding unit 20, and the second vibrometer 7 is disposed on the holding unit 20. With this configuration, the position and posture of the printing object W can be changed by driving the second robot 2A, so that the printing surface of the printing object W can be placed in a position and posture that makes it easy for the first robot 3 to print. This makes printing easier.

[0070] As described above, this embodiment has a holding device 2 that holds the printing object W, and the holding device 2 is the second robot 2A. With this configuration, the position and posture of the printing object W can be changed by driving the second robot 2A, so that the printing surface of the printing object W can be placed in a position and posture that makes it easy for the first robot 3 to print. This makes printing easier.

[0071] The fourth embodiment as described above can also achieve the same effects as the first embodiment described above.

[0072] 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]

[0073] REFERENCE SIGNS LIST 1...robot system, 10...mounting table, 2...holding device, 2A...second robot, 20...holding section, 21...mounting section, 22...claw section, 23...claw section, 28...second vibration-damping member, 3...first robot, 30...robot body, 31...base, 32...robot arm, 321...arm, 322...arm, 323...arm, 324...arm, 325...arm, 326...arm, 38...first vibration-damping member, 39...print head, 4...first vibration-generating device , 40... base, 400... piezoelectric actuator, 41... first stage, 42... second stage, 43... third stage, 44... fourth stage, 45... first stage drive section, 46... second stage drive section, 47... third stage drive section, 48... fourth stage drive section, 5... first vibrometer, 51... housing, 52... acceleration sensor unit, 52x... acceleration sensor, 52y... acceleration sensor, 52z... acceleration sensor, 53... Control IC, 54...detection element, 541...substrate structure, 541a...base, 541b...movable part, 542...quartz crystal vibration element, 542a...vibration beam, 542b...vibration beam, 543...weight part, 6...second vibration generator, 60...base, 61...first stage, 62...second stage, 63...third stage, 64...fourth stage, 65...first stage drive unit, 66...second stage drive unit, 67...third stage drive unit, 68...fourth stage drive unit, 7...second vibration meter, 71...housing, 72...acceleration sensor unit, 72x...acceleration sensor, 72y...acceleration sensor, 72z...acceleration sensor, 73...control IC, 80...robot body, 81...base, 82...robot arm, 9...control device, J1...joint, J2...joint, J3...joint, J4...joint, J5...joint, J6...joint, Q...printing trajectory, V1...vibration, V2...vibration, V3...vibration, V4...vibration, W...printing object

Claims

1. A printing method for printing on a printing object using a print head provided in a first robot, comprising: A printing method characterized in that the printing is performed by moving the print head and the object to be printed relatively while vibrating at least one of the print head and the object to be printed so as to reduce the relative vibration between the print head and the object to be printed.

2. The printing method according to claim 1 , further comprising the step of detecting vibration of either the print head or the printing object, and performing the printing while vibrating at least one of the print head and the printing object.

3. The printing method according to claim 1 , wherein the relative vibration is detected by detecting vibration of the print head and vibration of the printing object, respectively.

4. 4. The printing method according to claim 3, further comprising a first vibrometer for detecting vibrations of the print head, and a second vibrometer for detecting vibrations of the printing object.

5. The printing method of claim 4 , wherein the first vibrometer and the second vibrometer each include a quartz crystal vibrating element.

6. The printing method according to claim 1 , wherein the relative vibration is reduced by vibrating only the print head out of the print head and the printing object.

7. The printing method according to claim 1 , wherein the relative vibration is reduced by vibrating only the printing object out of the print head and the printing object.

8. A holding device for holding the printing object is provided, The printing method according to claim 7 , wherein the holding device is a second robot.

9. The printing method according to claim 2 or 3, wherein the printing is performed while detecting the relative vibration.

10. The printing method according to claim 2 or 3, wherein the printing is performed after the relative vibration is detected.

11. A first robot having a print head that performs printing on a print object, A robot system characterized in that the printing is performed by moving the print head and the object to be printed relatively while vibrating at least one of the print head and the object to be printed so as to reduce relative vibration between the print head and the object to be printed.

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