Printing method and robot system

Abstract

The invention provides a printing method and a robot system, which can detect the position of a print head even if a pattern for image recognition is not arranged on an object so as to perform high-precision printing. A printing method performs a printing job using a robot including: a robot body including a robot arm; a print head disposed on the robot arm; and an optical sensor which is provided with an image capturing element for capturing an image of an object and has a fixed relative positional relationship with the print head, the print method performing the print job on the object by moving the object and the print head relative to each other along a print path, the printing method detects an actual position of the print head by moving the print head along the print track and comparing two images captured by the imaging element at different imaging timings, and corrects the position of the print head based on a shift of the actual position with respect to the print track.

Description

Technical Field

[0001] The invention relates to a printing method and a robot system. Background Art

[0002] The printing system described in Patent Document 1 prints on an object by causing a robot having a print head mounted at the end to move along a printing track while ejecting ink toward the object. In addition, the printing system has a rotation angle sensor and a piezoelectric actuator. The rotation angle sensor is used to detect the actual position of the print head. The piezoelectric actuator is arranged between the print head and corrects the position of the print head based on the actual position of the print head. In this way, by correcting the position of the print head based on the actual position of the print head, printing without stripes (gap) is achieved.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-202781

[0004] However, in the printing system of Patent Document 1, the track of the print head vibrates due to vibration, making it difficult to perform high-precision printing. In addition, for example, if a pattern for image processing is not provided on the object, it is difficult to detect the vibration of the track. Summary of the invention

[0005] The printing method of the present invention uses a robot to perform printing operations, wherein the robot comprises: a robot body having a robot arm; a printing head arranged on the robot arm; and an optical sensor having an imaging element for imaging an object and having a fixed relative position relationship with the printing head.

[0006] The printing method performs the printing operation on the object by relatively moving the object and the printing head along a printing track.

[0007] The printing method detects the actual position of the printing head by moving the printing head along the printing track and comparing two images captured by the imaging element at different imaging timings.

[0008] The position of the print head is corrected based on an offset of the actual position relative to the print track.

[0009] The robot system of the present invention has:

[0010] A robot body having a mechanical arm;

[0011] A tool, configured on the robot arm, to perform work on an object;

[0012] an optical sensor having an imaging element for imaging the object and having a fixed relative positional relationship with the tool; and

[0013] The control device detects the actual position of the tool by moving the object and the tool relative to each other along the working track and comparing two images captured by the imaging element with different shooting timings, and corrects the position of the tool based on the offset of the actual position relative to the working track. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is an overall diagram of the robot system according to the first embodiment.

[0015] Figure 2 It is a schematic diagram showing the state of a printing job.

[0016] Figure 3 is a top view showing the mobile station.

[0017] Figure 4 is a cross-sectional view of an optical sensor.

[0018] Figure 5 is a schematic diagram showing the detection principle of the optical sensor.

[0019] Figure 6 This is a schematic diagram for explaining a method of detecting the position of a printing head.

[0020] Figure 7 is a flowchart for explaining the printing method.

[0021] Figure 8 This is a schematic diagram for explaining the problems of optical sensors.

[0022] Fig. 9 2 is a diagram showing the relationship between the translation amounts Δx and Δy.

[0023] Fig.10 2 is a diagram showing the relationship between the translation amounts Δx and Δy.

[0024] Fig.11 : is a figure which shows the method of measuring the inclination θ.

[0025] Fig.12 : is a figure which shows the method of measuring the inclination θ.

[0026] Fig.13 is a block diagram showing a circuit that generates an error signal.

[0027] Fig.14 is a block diagram showing a circuit for generating a vibration signal.

[0028] Fig.15 is a block diagram showing a circuit for generating a vibration signal.

[0029] Fig.16 is a block diagram showing a circuit for generating a vibration signal.

[0030] Fig.17 This is a flowchart for explaining a modified example of the printing method.

[0031] Fig.18 It is an overall diagram of a robot system according to a second embodiment.

[0032] Fig.19 It is a schematic diagram showing the state of a printing job.

[0033] Fig. 20 It is a schematic diagram showing the state of a printing job.

[0034] Fig.21 It is a schematic diagram showing the state of a printing job.

[0035] Description of Reference Numerals

[0036] 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…Ink ejection hole, 4…Moving stage, 40…Base, 400…Piezoelectric actuator, 41…First stage, 42…Second stage, 45…First stage drive unit, 46…Second stage drive unit, 5…Optical sensor, 50…Optical tracking sensor, 51…Base, 521…Lens component, 522…Lens component, 53…Light source, 54…Image capture element, 55…Processing circuit, 59…Holding component, 6…Abutment portion , 7…force sensor, 9…control device, A…first direction, B…second direction, D1…interval, D2…interval, Gn…image, Gn-1…image, I…ink, J1…joint, J2…joint, J3…joint, J4…joint, J5…joint, J6…joint, L…light, L1…solid line, L2…solid line, Pn…position, Pn-1…position, Q…printing track, S1…preliminary measurement step, S2…printing step, W…object, f1…linear function, f2…linear function, Δx…translation amount, Δx3…movement amount, Δy…translation amount, Δy3…movement amount, Δθ…rotation amount, θ…inclination DETAILED DESCRIPTION

[0037] Hereinafter, the printing method and the robot system of the present invention will be described in detail based on the embodiments shown in the drawings.

[0038] First embodiment

[0039] Figure 1 It is an overall diagram of the robot system according to the first embodiment. Figure 2 It is a schematic diagram showing the state of a printing job. Figure 3is a top view showing the mobile station. Figure 4 is a cross-sectional view of an optical sensor. Figure 5 is a schematic diagram showing the detection principle of the optical sensor. Figure 6 This is a schematic diagram for explaining a method of detecting the position of a printing head. Figure 7 is a flowchart for explaining the printing method. Figure 8 This is a schematic diagram for explaining the problems of optical sensors. Fig. 9 and Fig.10 These are diagrams showing the relationship between the translation amounts Δx and Δy, respectively. Fig.11 and Fig.12 These are diagrams showing a method of measuring the inclination θ. Fig.13 is a block diagram showing a circuit that generates an error signal. Figures 14 to 16 Each of them is a block diagram showing a circuit for generating a vibration signal. Fig.17 This is a flowchart for explaining a modified example of the printing method.

[0040] Figure 1 The robot system 1 shown is applied to a printing system that performs a printing operation on an object W. The robot system 1 includes a robot 10. The robot 10 includes a robot body 2, a printing head 3 as a tool mounted on the end of the robot body 2, a moving stage 4 disposed between the robot body 2 and the printing head 3, an optical sensor 5 disposed on the printing head 3, and a control device 9 that controls the driving of the robot 10.

[0041] Robot body 2

[0042] The robot body 2 is a six-axis vertical multi-joint robot with six drive axes, and has: a base 21 fixed to a mounting table, a floor, etc.; and a robot arm 22 rotatably connected to the base 21. The robot arm 22 is a structure in which six arms 221, 222, 223, 224, 225, and 226 are rotatably connected in sequence from the side of the base 21, and has six joints J1, J2, J3, J4, J5, and J6. Among these 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 driving mechanism is provided at each of the joints J1, J2, J3, J4, J5, and J6, and the driving mechanism has a motor as a driving source and an encoder for detecting the rotation amount of the joint.

[0043] The structure of the robot body 2 is not particularly limited. For example, the number of arms provided by the robot arm 22 is not limited to six. In addition, the robot body 2 may also be a dual-arm robot, a horizontal multi-joint robot (a robot with a selectively compliant assembly robot arm), etc. In addition, the robot body 2 may not be fixed to a mounting table, a floor, etc., but may be able to move on its own.

[0044] Printing head 3

[0045] The print head 3 is disposed at the end of the robot arm 22, that is, the arm 226. The print head 3 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 an ink ejection hole 31 connected to the ink chamber. The vibration plate vibrates to eject the ink I in the ink chamber from the ink ejection hole 31. Figure 2 As shown, the robot arm 22 is driven to move the print head 3 on a predetermined printing track Q relative to the object W, and the ink I is ejected from the print head 3 and adhered to the printed surface of the object W, thereby printing.

[0046] Mobile Station 4

[0047] The movable platform 4 is disposed between the arm 226 and the printing head 3 and is used to correct the position of the printing head 3. Figure 3 As shown, the movable stage 4 includes a base 40 supported by an arm 226 , a first stage 41 that moves straightly in a first direction A relative to the base 40 , and a second stage 42 that moves straightly in a second direction B orthogonal to the first direction A relative to the first stage 41 . The printing head 3 is arranged on the second stage 42 .

[0048] The moving stage 4 includes a first stage driving unit 45 that moves the first stage 41 in the first direction A relative to the base 40 and a second stage driving unit 46 that moves the second stage 42 in the second direction B relative to the first stage 41 .

[0049] The first stage driving unit 45 and the second stage driving unit 46 are respectively equipped with a piezoelectric actuator 400 that is driven by the expansion and contraction of the piezoelectric element caused by the energization, and the first stage 41 and the second stage 42 are moved 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 stage 41 and the second stage 42 can be finely and accurately controlled, and the switching of the movement direction also becomes agile. Therefore, the position correction of the printing head 3 can be performed with high precision. In addition, the miniaturization and lightweight of the moving stage 4 can also be achieved. Therefore, the increase in the end weight of the robot body 2 due to the configuration of the moving stage 4 can be minimized, thereby effectively suppressing the reduction in the driving characteristics of the robot body 2 such as responsiveness and vibration damping.

[0050] The structure of the moving stage 4 is not particularly limited. For example, the first stage driving unit 45 and the second stage driving unit 46 may also be structures using a driving source other than the piezoelectric actuator 400, such as a motor that rotates by energizing. In addition, the moving stage 4 may be omitted. In this case, the position correction of the printing head 3 may be performed by the robot arm 22.

[0051] Optical sensor 5

[0052] like Figure 3 As shown, the optical sensor 5 is disposed together with the print head 3 on the second stage 42 of the moving stage 4. Therefore, the relative positional relationship between the print head 3 and the optical sensor 5 is kept constant. The position of the print head 3 is detected based on the output of the optical sensor 5.

[0053] The optical sensor 5 is an optical tracking sensor 50 which is also widely used in optical mice. The optical tracking sensor 50 has two mutually orthogonal detection axes, namely the x-axis and the y-axis, and can detect the translation amount Δx in the x-axis direction and the translation amount Δy in the y-axis direction independently. In addition, the optical tracking sensor 50 is in a rectangular shape extending along the y-axis when viewed from above. The shape of the optical tracking sensor 50 is not particularly limited, and can be a rectangular shape extending along the x-axis, a square, a circle, etc.

[0054] like Figure 4 As shown, the optical tracking sensor 50 includes a base 51, a pair of lens components 521 and 522, a light source 53, an imaging element 54, and a processing circuit 55. The base 51 is arranged to face the object W. The light L emitted by the light source 53 is guided to the surface of the object W by the lens component 521 and the reflection surface formed on the inner surface of the base 51, reflected by the surface of the object W, and collected by the lens component 522 to be received by the imaging element 54. The imaging element 54 continuously captures images at a cycle of about 1 ms, and the processing circuit 55 obtains the translation amount of the optical tracking sensor 50 relative to the object W based on the image obtained by the imaging element 54.

[0055] Specifically, if Figure 5 As shown, by irradiating the object W with light L, light and dark corresponding to the minute concave-convex of the surface of the object W appear in the image captured by the imaging element 54. In addition, the processing circuit 55 compares the image Gn newly captured by the imaging element 54 with the image Gn-1 captured last time, and detects the movement amount of the image Gn relative to the image Gn-1 using the optical flow method or the like. In other words, the movement amount of the image Gn relative to the image Gn-1 is detected by comparing the brightness information of the image Gn with that of the image Gn-1. In addition, based on the detection result, the processing circuit 55 detects the translation amounts Δx and Δy of the optical tracking sensor 50 relative to the object W from the time when the image Gn-1 is acquired to the time when the image Gn is acquired.

[0056] In particular, as shown in this embodiment, by irradiating the object W with light L from an oblique direction, that is, a direction oblique to the normal line of the printed surface of the object W, the light and dark appear more clearly, and the translation amounts Δx and Δy can be detected with higher accuracy.

[0057] In addition, the light source 53 is not particularly limited, and for example, an LED (light emitting diode), a laser light source, etc. can be used. In addition, the light L from the light source 53 is not particularly limited, and for example, red light, blue light, infrared light, etc. can be used. In addition, the imaging element 54 is not particularly limited, and for example, a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal Oxide Semiconductor) image sensor, etc. can be used.

[0058] The optical tracking sensor 50 has been described above. As can be seen from the fact that the optical tracking sensor 50 is widely used in optical mice, it is cheap and small, and has high detection accuracy. Therefore, by using the optical tracking sensor 50 as the optical sensor 5, a robot system 1 that can achieve both low price and small size and high-precision position detection can be obtained.

[0059] Control device 9

[0060] The control device 9 controls the driving of the robot body 2, the printing head 3, the optical sensor 5, and the moving stage 4 independently or in conjunction with each other. The control device 9 is composed of, for example, a computer, and has a processor (CPU) for processing information, a memory connected to the processor in a communicable manner, and an external interface for connecting to an external device. The memory stores various programs that can be executed by the processor, and the processor can read and execute the programs stored in the memory.

[0061] In addition, the control device 9 detects the position of the print head 3 using the optical tracking sensor 50 in the following manner. As described above, the relative positional relationship between the optical tracking sensor 50 and the print head 3 is fixed. Figure 6 As shown, the control device 9 directly sets the translation amount Δx detected by the optical tracking sensor 50 as the movement amount Δx3 of the print head 3 in the direction along the x-axis, and directly sets the translation amount Δy as the movement amount Δy3 of the print head 3 in the direction along the y-axis. Furthermore, the control device 9 detects the position Pn of the print head 3 by adding the movement amounts Δx3 and Δy3 of the print head 3 detected this time to the position Pn-1 of the print head 3 detected last time. Whenever the optical tracking sensor 50 sends new translation amounts Δx and Δy, the control device 9 repeatedly performs the above-mentioned processing to update the latest position of the print head 3. In addition, the control device 9 can also detect the trajectory of the print head 3 by combining the repeatedly detected positions of the print head 3 in a time series.

[0062] The structure of the robot system 1 has been described above. Next, a method for printing an object W using the robot system 1 will be described. Figure 7 As shown in FIG. 1 , the printing method includes a preliminary measurement step S1 and a printing step S2. Hereinafter, each of these steps S1 and S2 will be described in detail.

[0063] In addition, in the printing method using the robot system 1, the printing track Q is composed only of the translation movement of the printing head 3, and substantially does not include the rotation movement of the printing head 3. As described above, the optical tracking sensor 50 can only detect the translation amounts Δx and Δy relative to the object W, but cannot detect the rotation amount Δθ relative to the object W. Therefore, Figure 8 As shown, if the printing track Q includes rotational motion, an offset occurs between the position of the print head 3 detected based on the translation amounts Δx and Δy and the actual position of the print head 3 (hereinafter, also referred to as the "actual position"). Therefore, by forming the printing track Q only by the translational motion of the print head 3, the offset between the position of the print head 3 detected based on the translation amounts Δx and Δy and the actual position of the print head 3 can be suppressed. Thus, even if an inexpensive optical tracking sensor 50 is used, the position of the print head 3 can be detected with high precision, thereby enabling high-precision printing. In addition, in this embodiment, a case where the printing track Q is set along the x-axis is described.

[0064] Preliminary measurement step S1

[0065] In this embodiment, since the printing track Q is set along the x-axis, Fig. 9 As shown by the solid line L1, the printing head 3 does not move in the y-axis direction during the movement along the printing track Q. However, for example, Fig.10 As shown in FIG. 1 , there is a case where the x-axis is tilted relative to the printing track Q due to the installation accuracy of the optical tracking sensor 50, the setting error of the printing track Q, etc. In other words, there is a case where the inclination of the x-axis relative to the printing track Q deviates from the designed value. If the x-axis is tilted relative to the printing track Q, the optical tracking sensor 50 continues to move in the y-axis direction while moving along the printing track Q. Therefore, as shown in FIG. Fig.10 As shown by the solid line L2 in FIG. 1 , although the print head 3 moves along the print track Q, the translation amount Δy continues to increase, and accordingly, the position of the print head 3 detected based on the translation amounts Δx and Δy deviates from the actual position of the print head 3 .

[0066] In addition, the vibration generated in the print head 3 also causes the actual position of the print head 3 to deviate from the printing track Q. In addition, Fig.10 The solid line L2 shows a state where the positional deviation of the optical tracking sensor 50 and the vibration generated in the print head 3 overlap.

[0067] Therefore, the control device 9 measures the inclination of the x-axis relative to the printing track Q in advance before the printing operation in the preliminary measurement step S1. Specifically, first, the control device 9 moves the printing head 3 along the printing track Q under the same conditions as the actual printing operation, except that the ink I is not ejected from the printing head 3, and measures the track of the printing head 3 based on the translation amounts Δx and Δy output from the optical tracking sensor 50. Fig.11 As shown, the control device 9 approximates the track measured by the least square method to a linear function f1, and stores the inclination of the approximated linear function f1 as the inclination θ of the x-axis relative to the printing track Q. Alternatively, Fig.12 As shown, a linear function f2 is obtained that makes the interval distance D1 from the start point of the printing track Q in the y-axis direction equal to the interval distance D2 from the end point in the y-axis direction, and the inclination of the obtained linear function f2 is stored as the inclination θ of the x-axis relative to the printing track Q. The calculation direction of the inclination θ is not particularly limited.

[0068] Moreover, if Fig.13 As shown, the control device 9 corrects the translation amounts Δx and Δy detected by the optical tracking sensor 50 using the inclination θ, and detects the actual position of the print head 3 based on the corrected value. In this way, by correcting the translation amounts Δx and Δy using the inclination θ, the inclination of the x-axis relative to the printing track Q can be eliminated, so that the actual position of the print head 3 can be detected with high accuracy. In this way, according to the robot system 1, even if a pattern for image recognition is not provided on the object W, the actual position of the print head 3 can be detected with high accuracy.

[0069] Furthermore, the control device 9 compares the actual position of the print head 3 with the print track Q, i.e., the target value, and generates an error signal indicating the amount of deviation of the actual position of the print head 3 relative to the print track Q. The error signal includes a moving direction error signal indicating the deviation in the direction along the print track Q, and an orthogonal direction error signal indicating the deviation in the direction orthogonal to the print track Q.

[0070] Next, the control device 9 extracts the vibration component from the error signal generated as described above, and generates a correction signal for correcting the position of the print head 3 .

[0071] Specifically, first, the control device 9 generates a vibration signal from which noise is removed by extracting a predetermined frequency component from the error signal. The vibration signal includes a moving direction vibration signal in which a predetermined frequency component is extracted from the moving direction error signal, and an orthogonal direction vibration signal in which a predetermined frequency component is extracted from the orthogonal direction error signal. In addition, in the present embodiment, the frequency component less than 3 Hz is set as a low-frequency noise, the frequency component above 3 Hz and below 50 Hz is set as a vibration component, and the frequency component exceeding 50 Hz is set as a high-frequency noise. However, there is no particular limitation on which frequency band is used as noise and which frequency band is used as a vibration component, and it can be appropriately set according to the characteristics of the device used.

[0072] There is no particular limitation on the method of generating a vibration signal based on the error signal. For example, Fig.14 As shown in FIG. 1 , a method of passing the error signal through a low-pass filter LPF can be cited. In this case, by using a low-pass filter LPF that allows frequency signals less than 3 Hz to pass, the passed frequency signal is removed from the error signal, thereby obtaining a vibration signal with low-frequency noise cut off. In addition, for example, Fig.15 As shown in FIG. 1 , a method of passing the error signal through a high-pass filter HPF can be cited. In this case, by using a high-pass filter HPF that passes a frequency signal of 3 Hz or more, a vibration signal with low-frequency noise cut off can be obtained. In addition, for example, Fig.16 As shown, the error signal is expressed in the frequency domain through Fourier transform (FFT), and then the frequency components above 3 Hz and below 50 Hz are extracted using a bandpass filter BPF. Finally, it is restored to the time domain expression through inverse Fourier transform (IFFT), thereby obtaining a vibration signal with low-frequency noise and high-frequency noise cut off.

[0073] Next, the control device 9 generates an inverted signal of the vibration signal as a correction signal. The correction signal includes a moving direction correction signal which is an inverted signal of the moving direction vibration signal and an orthogonal direction correction signal which is an inverted signal of the orthogonal direction vibration signal.

[0074] Printing step S2

[0075] In the printing step S2, the robot arm 22 is driven to move the print head 3 along the printing track Q, and the movable stage 4 is driven based on the correction signal to correct the position of the print head 3. In other words, the robot arm 22 is driven to move the print head 3 along the printing track Q, and the movable stage 4 is driven to eliminate the vibration of the print head 3.

[0076] According to such a method, the deviation of the actual position of the print head 3 relative to the print track Q can be suppressed to a smaller value, and preferably the actual position of the print head 3 can be made consistent with the print track Q. Therefore, high-precision printing can be performed. In particular, by eliminating the vibration of the print head 3 by driving the movable table 4, the responsiveness to the correction signal is improved compared to when the vibration of the print head 3 is eliminated by driving the robot arm 22. Therefore, the vibration of the print head 3 can be eliminated with higher precision, thereby enabling high-precision printing. However, the movable table 4 can also be omitted, and the vibration of the print head 3 can be eliminated by driving the robot arm 22.

[0077] The printing method using the robot system 1 is described above, but the printing method is not particularly limited. For example, in the aforementioned method, a correction signal is generated before the printing step S2, and in the printing step S2, the position of the printing head 3 is corrected using the correction signal generated in advance, but it is not limited to this. In the printing step S2, the offset of the printing head 3 relative to the printing track Q can also be detected in real time, and the movable stage 4 can be feedback-controlled based on the detection result.

[0078] In such a case, Fig.17 As shown, the printing method also has a preliminary measurement step S1 and a printing step S2. In the preliminary measurement step S1, the inclination θ is measured and stored. In the printing step S2, the control device 9 moves the print head 3 along the printing track Q, during which the actual position of the print head 3 is detected based on the translation amounts Δx, Δy and the inclination θ detected by the optical tracking sensor 50 at a predetermined period. Furthermore, the control device 9 generates a correction signal based on the offset of the actual position relative to the printing track Q, and uses the generated correction signal to perform feedback control on the drive of the movable stage 4. In this way, by detecting the offset of the print head 3 relative to the printing track Q in real time and performing feedback control on the movable stage 4 to reduce the offset, preferably to zero, the vibration of the print head 3 can be eliminated with high precision, thereby enabling high-precision printing. In addition, the method for measuring the inclination θ and the method for generating the correction signal can appropriately use the above-mentioned method, but cannot use Fig.16 The method shown.

[0079] The robot system 1 and the printing method using the robot system 1 have been described above. As described above, such a printing method is a printing method for performing a printing operation on an object W by relatively moving the object W and the print head 3 along the printing track Q using the robot 10, the robot 10 including: a robot body 2 having a robot arm 22; a print head 3 disposed on the robot arm 22; and an optical sensor 5 having an imaging element 54 for imaging the object W and having a fixed relative positional relationship with the print head 3, and the printing method moves the print head 3 along the printing track Q, compares two images captured by the imaging element 54 at different imaging timings, thereby detecting the actual position of the print head 3, and corrects the position of the print head 3 based on the deviation of the actual position from the printing track Q. According to such a configuration, since the position of the print head 3 is detected based on two images obtained by capturing the object W, even if a pattern for image recognition is not provided on the object W, the position of the print head 3 can be detected with high accuracy. In addition, by correcting the position of the print head 3 based on the detection result, the deviation of the print head 3 from the printing track Q can be suppressed. Therefore, high-precision printing can be performed.

[0080] In addition, as described above, the optical sensor 5 is an optical tracking sensor 50, and includes: a light source 53; a lens component 521 that irradiates the light L from the light source 53 to the object W; and an imaging element 54 that receives the light L reflected by the object W. The printing method detects the position of the printing head 3 by comparing the brightness information of the two images. According to such a structure, the position of the printing head 3 can be detected with high accuracy.

[0081] As described above, the optical sensor 5 irradiates the object W with light L from an oblique direction. This makes it easier for light and dark corresponding to minute irregularities on the surface of the object W to appear in the image captured by the imaging element 54 , and the position of the print head 3 can be detected with high accuracy.

[0082] In addition, as described above, the printing track Q is constituted by the translational movement of the printing head 3. Thus, even when the optical sensor 5 can detect only the translational movement of the printing head 3, the position of the printing head 3 can be detected with high accuracy.

[0083] In addition, as described above, the robot 10 has the moving stage 4, which is disposed between the robot arm 22 and the print head 3 and displaces the print head 3, and the robot 10 corrects the position of the print head 3 by driving the moving stage 4. As a result, compared with the case where the position of the print head 3 is corrected by driving the robot arm 22, the responsiveness is improved, and the position of the print head 3 can be corrected with higher accuracy.

[0084] In addition, as described above, the robot system 1 includes: a robot body 2 having a robot arm 22; a print head 3 as a tool, which is arranged on the robot arm 22 and operates on an object W; an optical sensor 5 having an imaging element 54 for imaging the object W and having a fixed relative positional relationship with the print head 3; and a control device 9, which detects the actual position of the print head 3 by moving the object W and the print head 3 relatively along the printing track Q as an operation track and comparing two images captured by the imaging element 54 at different imaging timings, and corrects the position of the print head 3 based on the deviation of the actual position from the printing track Q. According to such a structure, the position of the print head 3 can be detected based on the two images obtained by imaging the object W. Therefore, the position of the print head 3 can be detected with high accuracy.

[0085] In addition, as described above, the tool is the printing head 3 and the operation is printing. Thus, a high-precision printing operation can be performed.

[0086] Second embodiment

[0087] Fig.18 It is an overall diagram of a robot system according to a second embodiment. Figures 19 to 21 Each of them is a schematic diagram showing a state of a printing job.

[0088] The robot system 1 involved in this embodiment is the same as the robot system 1 of the first embodiment except that the robot 10 has a force sensor 7. In addition, in the following description, the robot system 1 of this embodiment is mainly described with respect to the differences from the first embodiment, and the description of the same matters is omitted. In addition, in each figure of this embodiment, the same reference numerals are marked for the same structures as those in the above embodiment.

[0089] like Fig.18 As shown, in the robot system 1 of this embodiment, the optical tracking sensor 50 is arranged to protrude toward the object W side more than the printing head 3. In addition, a force sensor 7 is arranged between the robot body 2 and the moving stage 4. The force sensor 7 has three mutually orthogonal detection axes, and can independently detect the translation force (axial force) along each detection axis and the rotation force (torque) around each detection axis. In such a robot system 1, the contact between the optical tracking sensor 50 and the object W is detected using the force sensor 7.

[0090] According to this structure, Fig.19As shown, by feeding back the detection result of the force sensor 7, the optical tracking sensor 50 can be brought into light contact with the object W with a predetermined force while the print head 3 is moved along the printing track Q. According to such a method, the distance between the optical tracking sensor 50 and the object W can be kept constant. Therefore, the detection error of the optical tracking sensor 50 caused by the change of the distance between the optical tracking sensor 50 and the object W can be reduced, so that the translation amounts Δx and Δy can be detected with higher accuracy. In addition, the distance between the print head 3 and the object W can be kept constant, so that printing with higher accuracy can be performed.

[0091] In the above example, the optical tracking sensor 50 is brought into contact with the object W, but the present invention is not limited thereto. Fig. 20 As shown in the figure, a contact portion 6 for contacting with the object W may be separately arranged, and the contact portion 6 may be brought into contact with the object W. Moreover, for example, by bringing the contact portion 6 into contact with a position of the object W that does not overlap with the printed area or with an area of ​​the printed area that has not been printed, while printing is performed, it is possible to suppress contact with the ink I that is not completely dried. Therefore, printing with higher precision can be performed. In addition, in the example shown in the figure, the contact portion 6 protrudes from the holding member 59, but the structure of the contact portion 6 is not particularly limited.

[0092] In addition, when the force sensor 7 detects that the optical tracking sensor 50 is in contact with the object W, the optical tracking sensor 50 is controlled to be slightly separated from the object W so that they are not in contact, thereby Fig.21 As shown, the print head 3 can also be moved so as to pass near the surface of the object W. According to such a method, the distance between the print head 3 and the object W can be further reduced, and the variation of the distance can be suppressed, so that printing with higher precision can be performed.

[0093] As described above, in the robot system 1 of the present embodiment, the robot 10 has the force sensor 7, the force sensor 7 detects contact with the object W, and the robot system 1 corrects the position of the print head 3 based on the detection result of the force sensor 7. Thus, the change in the distance between the print head 3 and the object W can be suppressed, so that higher-precision printing can be performed.

[0094] The printing method and robot system of the present invention are described above based on the illustrated embodiments, but the present invention is not limited thereto, and the structures and processes of each part can be replaced by any structures and processes having the same functions. For example, the processes can be replaced by conveyor tracking, adhesive coating, grinding, welding, etc., and any tool can be used instead of the print head. In addition, other arbitrary structures and processes can also be added to the present invention. In addition, the various embodiments can also be appropriately combined.

Claims

1. A printing method, characterized in that: Using robots for printing operations, The robot comprises: a robot body having a robot arm; a printing head arranged on the robot arm; and an optical sensor having an imaging element for imaging an object and having a fixed relative positional relationship with the printing head. The printing method performs the printing operation on the object by relatively moving the object and the printing head along a printing track. The printing method detects the actual position of the printing head by moving the printing head along the printing track and comparing two images captured by the imaging element at different imaging timings. The position of the print head is corrected based on an offset of the actual position relative to the print track.

2. The printing method according to claim 1, characterized in that: The optical sensor is an optical tracking sensor, The optical sensor comprises: light source; a lens component for irradiating the light from the light source to the object; and The imaging element receives the light reflected by the object. The printing method detects the movement amount of the printing head by comparing the brightness information of the two images.

3. The printing method according to claim 2, characterized in that: The optical sensor irradiates the light toward the object from an oblique direction.

4. The printing method according to claim 2, characterized in that: The printing track is constituted by a translational movement of the printing head.

5. The printing method according to claim 1, characterized in that: The robot has a force sensor, and the force sensor detects contact with the object. The printing method corrects the position of the printing head based on the detection result of the force sensor.

6. The printing method according to claim 1, characterized in that: The robot has a moving platform, which is arranged between the robot arm and the printing head and moves the printing head. The printing method corrects the position of the printing head by driving the moving stage.

7. A robot system, characterized in that: have: A robot body having a mechanical arm; A tool, which is arranged on the robot arm and operates on the object; an optical sensor having an imaging element for imaging the object and having a fixed relative positional relationship with the tool; as well as The control device detects the actual position of the tool by moving the object and the tool relative to each other along the working track and comparing two images captured by the imaging element with different shooting timings, and corrects the position of the tool based on the offset of the actual position relative to the working track.

8. The robot system according to claim 7, characterized in that: The tool is a printing head, The job is printing.

Images