Printing method

Abstract

The present invention provides a printing method. A first image (I1) and a second image (I2) are printed while changing the relative position and relative posture of a printing head (32) relative to a printing object (10). The method comprises a first printing step, a detection step, an adjustment step, and a second printing step. In the first printing step, a first printed image (P1) having an opening area (B1, B2, B3) formed in the first image is printed; in the detection step, the opening area is detected; in the adjustment step, the printing head is adjusted so that the second image is adjacent to the first image; and in the second printing step, a second printed image (P2) including the second image and partial images (D1, D2, D3) is printed. Thus, white stripes or black stripes can be prevented from being generated on the printed image without compromising image quality.

Description

Technical Field

[0001] The present invention relates to a printing method. Background Art

[0002] Japanese Patent Application Laid-Open No. 07-137248 discloses a method for printing specific markings on a substrate. The amount of material transported and the amount of deflection of ink droplets ejected from an electrostatic deflection inkjet nozzle are adjusted based on the interval between marking print positions. This prevents white or black streaks from appearing on the printed image. Summary of the Invention

[0003] According to the printing method disclosed in Japanese Patent Application Laid-Open No. 07-137248, there is a technical problem in that a mark remains on the printed object, thereby deteriorating the image quality.

[0004] The purpose of the present invention is to solve the above-mentioned technical problems.

[0005] One embodiment of the present invention is a printing method, which uses the printing head to print a first image and a second image on the printing object while changing the relative position and relative posture of the printing head relative to the printing object. The printing method is characterized in that it has a first printing step, a detection step, an adjustment step and a second printing step, wherein, in the first printing step, the printing head is used to print a first printed image with an opening area formed in the first image on the printing object; in the detection step, the opening area is detected using a sensor provided on the printing head based on the relative position and relative posture of the printing head when printing the second image; in the adjustment step, the relative position and relative posture of the printing head are adjusted in a manner such that the second image is adjacent to the first image based on the detected opening area; and in the second printing step, the printing head is used to print a second printed image including the second image and a partial image printed in the opening area on the printing object.

[0006] According to the present invention, it is possible to prevent white streaks or black streaks from being generated on a printed image without deteriorating the image quality.

[0007] The above-mentioned objects, features, and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a diagram illustrating how an image is printed on a printing object using a printing method according to one embodiment.

[0009] Figure 2This is a diagram schematically showing the configuration of a gripping device, a printing device, and a storage device.

[0010] Figure 3 This is a diagram illustrating how the relative position and posture of the print head relative to the printing object are changed.

[0011] Figure 4A A diagram schematically shows a first image and a second image adjacent to each other. Figure 4B It is a diagram schematically showing the first printed image. Figure 4C It is a diagram schematically showing the second printed image.

[0012] Figure 5 This is a flowchart showing a processing procedure for printing a first print image and a second print image on a print object.

[0013] Figure 6A This is a diagram schematically showing a first printed image printed on a printing object by a printing method according to Modification 1. Figure 6B It is a diagram schematically showing the second printed image.

[0014] Figure 7A This is a diagram schematically showing a captured image of a first printed image printed by the printing method according to Modification 2. Figure 7B It is a diagram schematically showing the second printed image.

[0015] Figure 8 This is a flowchart showing a processing procedure for printing a first print image and a second print image on a print object in Modification 2. DETAILED DESCRIPTION

[0016] Figure 1 This figure illustrates an embodiment of an image printed on a printing object 10 using a printing method. The printing object 10 is, for example, an instrument panel used for the interior of a car. In this embodiment, the printing object 10 has an uneven three-dimensional printing surface, but the printing object 10 may also have a two-dimensional printing surface. The printing object 10 is gripped by a gripping device 20. The gripping device 20 is, for example, a robot having a multi-axis articulated robot arm 22. A gripping portion (not shown) is mounted on the end of the robot arm 22. The printing object 10 is gripped by this gripping portion.

[0017] The printing device 30 prints an image on the print object 10. The printing device 30 includes a print head 32, multiple ink tanks 34, a carriage 36, a guide rail 38, and a sensor 40. The print head 32 carries multiple ink tanks 34 of different colors. During printing, each ink tank 34 ejects ink droplets along the Z-axis direction (the direction of gravity) onto the printing surface of the print object 10. The carriage 36 moves the print head 32 along the guide rail 38 during printing. The guide rail 38 extends linearly along the X-axis direction (horizontal direction). The Y-axis direction (horizontal direction) is perpendicular to the Z-axis and X-axis directions.

[0018] The sensor 40 is provided on the print head 32. The sensor 40 is, for example, a camera. In this embodiment, the detection process performed by the sensor 40 represents the imaging process performed by the camera. When the camera images the printed surface of the print object 10, a captured image is generated.

[0019] When printing an image on the print object 10, the print head 32 ejects ink droplets while moving along the guide rail 38. While the print head 32 is moving, the gripping device 20 moves the print object 10, maintaining the gap between the print head 32 and the printing surface of the print object 10 within a specified value. This changes the relative position and posture of the print head 32 with respect to the print object 10. In the following description, the relative position and posture of the print head 32 with respect to the print object 10 will be referred to simply as the relative position and relative posture of the print head 32, respectively.

[0020] Figure 2 This figure schematically illustrates the configuration of the gripping device 20, the printing device 30, and the storage device 60. The gripping device 20 is mounted on a movable base (not shown). In addition to the aforementioned robot arm 22, the gripping device 20 further includes a control unit 200 and a drive unit 210. The drive unit 210 is, for example, a motor.

[0021] The control unit 200 controls the drive unit 210, which in turn moves the robot arm 22. By moving the robot arm 22 in this manner, the printing object 10 can be moved in various directions. The control unit 200 controls the drive unit 210, which in turn moves the gripping device 20. By moving the gripping device 20 in this manner, the printing object 10 can be moved in the X-axis and Y-axis directions. Alternatively, the gripping device 20 can be moved by a device external to the gripping device 20, instead of the drive unit 210.

[0022] The control unit 200 includes a processing circuit and a storage unit. The processing circuit includes a processor such as a CPU. The storage unit includes volatile memory such as RAM and non-volatile memory such as ROM and flash memory. The storage unit stores programs, etc. The processing circuit executes the programs, thereby controlling the robot arm 22 and the drive unit 210.

[0023] The printing device 30 further includes a control device 300 and a drive device 310. The drive device 310 is, for example, a motor. When printing an image, the control device 300 controls the drive device 310 to move the carriage 36 along the guide rails 38 in the X-axis direction. This causes the print head 32 to move along the guide rails 38 in the X-axis direction. When printing an image, the control device 300 also controls the print head 32 to eject ink droplets from the ink tank 34 toward the printing surface of the print object 10.

[0024] The control device 300 includes a processing circuit and a storage unit. The processing circuit includes a processor such as a CPU. The storage unit includes volatile memory such as RAM and non-volatile memory such as ROM and flash memory. The storage unit stores programs, etc. The processing circuit executes the programs, allowing the control device 300 to control the print head 32, sensor 40, and drive device 310, and to communicate with the control unit 200 of the gripping device 20.

[0025] The storage device 60 stores image data 410. The image data 410 is data of an image to be printed on the printing object 10. The control device 300 of the printing device 30 prints a print image on the printing object 10 based on the image data 410.

[0026] The control device 300 controls the print head 32 and the drive device 310 to print an image on the print object 10. At this point, the drive device 310 moves the print head 32 in the X-axis direction. Furthermore, the control device 300 communicates with the control unit 200 of the gripping device 20, so that the control unit 200 controls the drive unit 210 to move the print object 10. In this way, as specified in the program, the print head 32 changes its relative position and posture relative to the print object 10 while printing an image on the print object 10.

[0027] Figure 3 : is a diagram illustrating how the relative position and relative posture of the print head 32 with respect to the printing object 10 are changed. Figure 3 In the embodiment, a first image and a second image are printed adjacent to each other in a first area A1 and a second area A2 of the printing surface of the printing object 10. The printing surface of the printing object 10 has a non-flat three-dimensional shape.

[0028] When printing the first image in the first area A1, the relative position of the print head 32 is set to a position substantially directly above the first area A1. In this case, the relative posture of the print head 32 is set so that the value of the gap G1 between the print head 32 and the first area A1 is within a predetermined value G0. When the first image is printed in the first area A1, the relative position of the print head 32 is shifted by moving the print object 10, and the second image is printed in the second area A2.

[0029] When printing the second image on the second area A2, the relative position of the print head 32 is set to a position substantially directly above the second area A2. In this case, the relative posture of the print head 32 is set so that the value of the gap G2 between the print head 32 and the second area A2 is within the above-mentioned predetermined value G0. Figure 3 In the example shown, the relative position and relative posture of the print head 32 when printing the first image I1 are different from the relative position and relative posture of the print head 32 when printing the second image I2.

[0030] Figure 4A This figure schematically illustrates adjacent first and second images I1 and I2. These images are printed on a non-flat, three-dimensional printing surface. As mentioned above, the relative position and orientation of the print head 32 differ between when printing the first image I1 and when printing the second image I2. In this case, even though printing proceeds according to the program, the second image I2 may not be printed closely adjacent to the first image I1. Specifically, the second image I2 may be printed separately from the first image I1 or partially overlap with it.

[0031] If the first image I1 and the second image I2 are not closely adjacent, white or black streaks may appear on the printed image. In this embodiment, the relative position and posture of the print head 32 are adjusted as follows to ensure that the first image I1 and the second image I2 are closely adjacent.

[0032] Figure 4B This figure schematically illustrates a first printed image P1. The first printed image P1 can be formed by forming an opening area B1 within the first image I1. The opening area B1 is a portion of the first printed image P1 where the image is partially absent. Using the relative position and orientation of the print head 32 when printing the first image I1, the first printed image P1 is printed on the printing surface of the print object 10, replacing the first image I1.

[0033] Specifically, the control device 300 of the printing device 30 obtains first image data for forming the opening area B1 within the first image I1 from the image data 410. The control device 300 controls the print head 32 and the drive device 310 while communicating with the control unit 200 of the gripping device 20, and prints the first print image P1 on the print object 10 based on the first image data. The gripping device 20 sets the print object 10 to the posture for printing the first image I1.

[0034] When printing the first printed image P1, the relative position and relative posture of the print head 32 are changed. When printing the second image I2, the relative position and relative posture of the print head 32 are detected using a sensor 40 provided on the print head 32. Based on the detected opening area B1, the relative position and relative posture of the print head 32 are adjusted by the gripping device 20 so that the second image I2 is adjacent to the first image I1.

[0035] Figure 4C This figure schematically illustrates the second printed image P2. The second printed image P2 includes a second image I2 and a partial image D1 of the first image I1. The image in the same area of ​​the first image I1 as the opening area B1 of the first printed image P1 is the partial image D1. When the partial image D1 is printed on the opening area B1 without offset, the first image I1 is completely printed.

[0036] As described above, the relative position and posture of the print head 32 are adjusted based on the opening area B1. Therefore, when the partial image D1 of the second printed image P2 is printed on the opening area B1 without offset, no white or black streaks are generated at the boundary between the first image I1 and the second image I2. Thus, the second image I2 is printed adjacent to the first image I1.

[0037] Specifically, the control device 300 of the printing device 30 obtains second image data including the second image I2 and the partial image D1 from the image data 410. The control device 300 controls the print head 32 and the drive device 310 while communicating with the control unit 200 of the gripping device 20, and prints the second print image P2 on the print object 10 based on the second image data. The gripping device 20 sets the print object 10 to the posture for printing the second image I2.

[0038] Furthermore, the smaller the opening area B1 and the partial image D1, the more accurately the partial image D1 can be printed without shifting from the opening area B1. Therefore, it is preferable that the opening area B1 and the partial image D1 be small. However, the opening area B1 and the partial image D1 must be large enough to be detected by the sensor 40. Furthermore, it is preferable that the opening area B1 be formed closer to the end of the first printed image P1 than the center.

[0039] Figure 5 This flowchart shows the process sequence for printing a first print image P1 and a second print image P2 on a print object 10. This process sequence is performed, for example, by a processing circuit included in the control device 300 of the printing device 30 executing a program. When this process sequence begins, in step S10, the control device 300 acquires image data 410 from the storage device 60. Specifically, the control device 300 acquires the first image data and the second image data described above.

[0040] In step S20, the control device 300 controls the print head 32 to set the relative position and relative posture of the print head 32 with respect to the printing object 10. The relative position and relative posture of the print head 32 are set to the relative position and relative posture of the print head 32 when printing the first image I1. In step S30, the control device 300 controls the print head 32 to print the first print image P1 on the printing surface of the printing object 10 based on the first image data.

[0041] In step S40, the control device 300 controls the print head 32 to set the relative position and relative posture of the print head 32 with respect to the printing object 10. The relative position and relative posture of the print head 32 are set to the relative position and relative posture of the print head 32 when printing the second image I2. In step S50, the control device 300 controls the sensor 40 to detect the opening area B1.

[0042] In step S60, the control device 300 controls the print head 32 so that the partial image D1 is printed without being offset from the opening area B1. That is, the control device 300 adjusts the relative position and relative posture of the print head 32 based on the detected opening area B1.

[0043] In step S80, the control device 300 controls the print head 32 to print the second print image P2 on the printing surface of the print object 10 based on the second image data. Thus, the second image I2 is printed adjacent to the first image I1. When the processing of step S80 is completed, the processing sequence ends.

[0044] [Modification]

[0045] The above-mentioned embodiment may be modified as follows.

[0046] (Variation 1)

[0047] In the above embodiment, the first printed image P1 is obtained by forming the opening region B1 in the first image I1. The first printed image P1 may also be obtained by forming a plurality of opening regions separated from each other in the first image I1.

[0048] Figure 6A Schematically illustrates a first printed image P1 printed on a printing object 10 by a printing method according to Modification 1. In this modification, the first printed image P1 is obtained by forming three opening areas B1, B2, and B3 separated from each other within a first image I1.

[0049] Figure 6B This figure schematically illustrates the second printed image P2. The second printed image P2 includes a second image I2 and partial images D1, D2, and D3 of the first image I1. The images of the same areas of the first image I1 as the openings B1, B2, and B3 of the first printed image P1 are partial images D1, D2, and D3. Partial images D1, D2, and D3 are printed without shifting relative to the openings B1, B2, and B3, respectively. As a result, the first image I1 is completely printed.

[0050] Since the first printed image P1 has two opening areas B1 and B2 separated from each other, it is possible to prevent the second image I2 from being displaced in the rotational direction relative to the first image I1.

[0051] exist Figure 6A In the example shown, the first image I1 and the first printed image P1 have rectangular outlines. The two opening areas B1 and B3 are located at separate positions on the diagonal line of the first image I1. In other words, the first printed image P1 has two opening areas B1 and B3 on the diagonal line. This allows for precise adjustment of the relative position and posture of the print head 32 when printing the second printed image P2.

[0052] (Variation 2)

[0053] In the above embodiment, the first printed image P1 is obtained by forming the opening area B1 in the first image I1. Figure 4B In the example of the first printed image P1 shown, the opening area B1 is rectangular. In an image obtained by capturing the printed first printed image P1 at the relative position and orientation of the print head 32 when printing the second image I2, the opening area B1 may not be rectangular.

[0054] Furthermore, printing on a non-flat three-dimensional printing surface may cause deformation of the opening region B1. In this case, the shape of the opening region B1 may also be deformed into a non-rectangular shape in an image obtained by the same imaging.

[0055] Figure 7A 1 is a diagram schematically showing a captured image 500 of a first printed image P1 printed by a printing method according to Modification 2. The shape of the opening region B1 detected from the captured image 500 is deformed into a non-rectangular shape.

[0056] Figure 7B This figure schematically illustrates a second printed image P2. The second printed image P2, consisting of a second image I2 and a partial image D1 corrected based on the shape of the detected opening area B1, is printed on the printing surface of the print object 10. The partial image D1 is printed without being offset from the opening area B1. Simultaneously, the second image I2 is printed adjacent to the first image I1.

[0057] Specifically, the control device 300 of the printing device 30 obtains second image data including the second image I2 and the partial image D1 from the image data 410. The control device 300 corrects the second image data so that the partial image D1 conforms to the shape of the detected opening area B1. While communicating with the control unit 200 of the gripping device 20, the control device 300 controls the print head 32 and the drive device 310, and prints the second print image P2 on the print object 10 based on the corrected second image data. The gripping device 20 sets the print object 10 to the posture for printing the second image I2.

[0058] Figure 8 This is a flowchart showing the process sequence for printing the first print image P1 and the second print image P2 on the print object 10 in the second modification. This process sequence is performed, for example, by the processing circuit of the control device 300 of the printing device 30 executing a program. This process sequence includes the processes of steps S10 to S80. The processes of steps S10 to S60 and step S80 have been used. Figure 5 The flowchart shown in FIG. 4 is used to explain these processes, and therefore the explanation of these processes is omitted here.

[0059] When step S60 is complete, the process proceeds to step S70. In step S70, the control device 300 corrects the partial image D1 based on the shape of the opening area B1 detected in step S60. The second printed image P2 includes the second image I2 and the corrected partial image D1. When step S70 is complete, the process proceeds to step S80. When step S80 is complete, the process ends.

[0060] (Variation 3)

[0061] In the above embodiment, the second image data includes the second image I2 and the partial image D1. However, the second image data may also correspond only to the second image I2. In this case, the image data 410 also includes the partial image data corresponding to the partial image D1. The control device 300 adjusts the relative position and relative posture of the print head 32 based on the detected opening area B1, and then prints the second printed image P2 on the printing surface of the printing object 10. At this time, the control device 300 prints the second printed image P2 on the printing surface of the printing object 10 based on the second image data and the partial image data.

[0062] The present invention is not limited to the above-described embodiment and modifications, and various configurations can be employed without departing from the spirit of the present invention.

[0063] [Inventions that can be achieved according to the embodiments]

[0064] The invention that can be grasped based on the above-described embodiment and modifications is described below.

[0065] (1) A printing method, wherein a first image (I1) and a second image (I2) are printed on a printing object (10) using a printing head (32) while changing the relative position and relative posture of the printing head (32) relative to the printing object (10), the method comprising a first printing step, a detection step, an adjustment step, and a second printing step, wherein in the first printing step, a first printed image (P1) having opening areas (B1, B2, B3) formed in the first image is printed on the printing object using the printing head; in the detection step, the first printed image (P1) is printed on the printing object using the printing head; and in the detection step, the first printed image (P1) is printed on the printing object. The relative position and relative posture of the print head when printing two images are detected by using a sensor (40) provided on the print head; in the adjustment step, the relative position and relative posture of the print head are adjusted in a manner such that the second image is adjacent to the first image based on the detected opening area; and in the second printing step, the print head is used to print a second printed image (P2) including the second image and the partial image (D1, D2, D3) printed in the opening area on the printing object. In this way, white stripes or black stripes can be prevented from being generated on the printed image without deteriorating the image quality.

[0066] (2) In the second printing step, the second printed image may be printed, including the second image and the partial image corrected based on the detected shape of the opening area. Thus, even when the printing object has an uneven three-dimensional printing surface, white or black streaks can be prevented from occurring in the printed image.

[0067] (3) The first printed image may include a plurality of mutually separated opening areas, and in the second printing step, the plurality of partial images may be printed on the plurality of opening areas, respectively. This can prevent white or black streaks from occurring on the printed image with high precision.

[0068] (4) The outline of the first image may be rectangular, and at least two of the plurality of opening areas may be located on a diagonal line of the first image. This can prevent white or black stripes from being generated on the printed image with high precision.

[0069] (5) In the first printing step, the first printed image may be printed on the printing object based on first image data obtained by forming the opening area within the first image, and in the second printing step, the second printed image may be printed on the printing object based on second image data including the second image and the partial image. This makes it possible to easily prevent white streaks or black streaks from occurring in the printed image.

[0070] (6) The printing method may further include a correction step in which the second image data is corrected so that the partial image has the shape of the detected opening area, and in the second printing step, the second printed image is printed on the printing object based on the corrected second image data. Thus, even when the printing surface has a concave-convex shape, white or black streaks can be prevented from occurring in the printed image.

[0071] (7) The printing object may have a non-flat three-dimensional printing surface, and in the correction step, the second image data is corrected based on deformation of the opening region caused by printing on the three-dimensional printing surface. Thus, even when the printing object has a non-flat three-dimensional printing surface, white or black streaks can be prevented from occurring in the printed image.

[0072] (8) The printing object may have a non-flat three-dimensional printing surface. In the adjustment step, the relative position and relative posture of the printing head are adjusted while the gap (G1, G2) between the printing head and the printing surface is within a predetermined value (G0). Thus, even when the printing object has a non-flat three-dimensional printing surface, turbulence in ink ejection can be suppressed, thereby enabling high-precision printing.

[0073] (9) The relative position and relative posture of the print head can be changed by driving the print object by holding the print object with a holding device (20). In the first printing step, the first print image is printed on the print object. Thereafter, in the second printing step, the drive device (310) drives the print head in a predetermined direction to print the second print image on the print object. This can suppress ink ejection disturbances, thereby enabling high-precision printing.

[0074] (10) The sensor may be a camera, and in the detection step, the opening area is detected based on the image (500) captured by the camera. Thus, the relative position and posture of the print head relative to the printed object can be precisely adjusted, thereby preventing white or black streaks from being generated on the printed image with high precision.

Claims

1. A printing method for printing a first image and a second image on a printing object using a printing head while changing the relative position and relative posture of the printing head with respect to the printing object, characterized in that: The method comprises a first printing step, a detection step, an adjustment step and a second printing step, wherein: In the first printing step, a first printed image having an open area formed in the first image is printed on the printing object using the printing head; In the detecting step, the opening area is detected using a sensor provided on the printing head based on the relative position and the relative posture of the printing head when printing the second image; In the adjusting step, the relative position and the relative posture of the printing head are adjusted based on the detected opening area so that the second image is adjacent to the first image; In the second printing step, a second printed image including the second image and the partial image printed in the opening area is printed on the printing object using the print head.

2. The printing method according to claim 1, wherein In the second printing step, the second printed image including the second image and the partial image corrected based on the detected shape of the opening area is printed.

3. The printing method according to claim 1 or 2, characterized in that The first printed image includes a plurality of opening areas separated from each other, In the second printing step, a plurality of the partial images are printed on a plurality of the opening areas, respectively.

4. The printing method according to claim 3, characterized in that The outline of the first image is a rectangle, At least two of the plurality of opening areas are located on a diagonal line of the first image.

5. The printing method according to claim 1, wherein In the first printing step, the first printed image is printed on the printing object based on first image data obtained by forming the opening area in the first image. In the second printing step, the second print image is printed on the printing object based on second image data including the second image and the partial image.

6. The printing method according to claim 5, characterized in that The method further comprises a correction step of correcting the second image data so that the partial image has the shape of the detected opening area. In the second printing step, the second print image is printed on the printing object based on the corrected second image data.

7. The printing method according to claim 6, characterized in that The printing object has a non-flat three-dimensional printing surface. In the correction step, the second image data is corrected based on deformation of the opening area caused by printing on the three-dimensionally shaped printing surface.

8. The printing method according to claim 1, wherein: The printing object has a non-flat three-dimensional printing surface. In the adjusting step, the relative position and the relative posture of the print head are adjusted in a state in which the interval between the print head and the printing surface is within a predetermined value.

9. The printing method according to claim 8, characterized in that The relative position and the relative posture of the print head are changed by driving the print object by a holding device holding the print object. In the first printing step, the first print image is printed on the print object. Thereafter, in the second printing step, the drive device drives the print head in a predetermined direction to print the second print image on the print object.

10. The printing method according to claim 1, wherein The sensor is a camera, In the detecting step, the opening area is detected based on the image captured by the camera.

Images