JP7551524B2 - Printing System - Google Patents

Description

The present invention relates to a tandem printing system that keeps the printing misalignment between the upstream and downstream machines within an acceptable range.

Conventionally, there are duplex printing devices that have a circulating transport path that includes a paper inversion path, print one side of paper fed from a paper feed tray, transport the paper with the print on one side along the paper inversion path to invert it, and then print on the other side, thereby performing duplex printing.

In this type of double-sided printing device, paper fed from the paper feed tray and paper inverted by the paper inversion path are transported alternately, resulting in longer printing times than when printing on one side.

Patent Document 1 discloses a technology for a tandem printing system in which upstream and downstream machines having the same configuration are arranged in series, with the upstream machine printing on one side of the paper and the downstream machine printing on the other side.

Here, paper skew correction is performed for both the upstream and downstream machines so that printing occurs in the appropriate location on the transported paper.

For example, Patent Document 2 discloses a printing device that calculates the angle difference of the head from a printed test pattern and adjusts the inclination in a direction that eliminates the angle difference.

JP 2013-202907 A JP 2011-126206 A

However, even if the tilt adjustment technology of Patent Document 2 is applied to the tandem printing system described in Patent Document 1, the technology of Patent Document 2 adjusts the angle difference in the tilt of the recording head within one printer. Therefore, when multiple printers are linked together to form an image on the same surface, as in the tandem printing system described in Patent Document 1, the transport direction of the multiple printers and the tilt of the printing units cannot be synchronized, and skew correction may not be performed properly.

As a result, the printing misalignment between the upstream and downstream machines can exceed the tolerance range, causing the finished print quality to deteriorate.

The present invention was made in consideration of the above problems, and aims to provide a tandem printing system that keeps the printing misalignment between the upstream and downstream machines within an acceptable range.

In order to achieve the above object, the printing system according to the present invention is characterized by:
A printing system including a first printing device that prints on a transported sheet of paper based on a print job by ejecting ink from nozzle rows of a plurality of first printing units, and a second printing device that prints on the sheet of paper printed by the first printing device by ejecting ink from nozzle rows of a plurality of second printing units,
calculating an installation angle of each of the first printing units and the second printing units with respect to the transport direction from a straight line printed in the transport direction of the paper and a straight line printed in the direction of the nozzle array based on a specific chart image obtained by scanning a paper printed by the first printing device and the second printing device based on a specific chart for angle adjustment;
calculating an average angle of the plurality of first print units as a first average angle and an average angle of the plurality of second print units as a second average angle based on the calculated installation angles;
The present invention is characterized in that it includes an adjustment angle calculation means for calculating an adjustment angle of the plurality of first printing units or the plurality of second printing units such that the second average angle relative to the calculated first average angle falls within a predetermined range.

The printing system according to the present invention has the following features: It is possible to keep the printing misalignment between the upstream and downstream machines within an acceptable range.

1 is a schematic configuration diagram of a tandem printing system according to a first embodiment of the present invention. 1 is a block diagram showing functions of a tandem printing system according to a first embodiment of the present invention; 1A is a diagram showing an example of first image data and second image data of a specific chart for angle adjustment included in a job, and FIGS. 1B and 1C are diagrams showing an example of a specific chart image read by a scanner. FIG. 4 is a diagram showing an example of a specific chart image read by a scanner. 4 is a flowchart showing the process of the tandem printing system according to the first embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. The same or equivalent parts and components are designated with the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual product. In addition, the drawings may include parts with different dimensional relationships and ratios.

The embodiments shown below are merely examples of devices that embody the technical ideas of this invention, and the technical ideas of this invention do not limit the layout of each component to those shown below. The technical ideas of this invention can be modified in various ways within the scope of the claims.

[Configuration of this embodiment]
First, a configuration of a tandem printing system 1 according to a first embodiment of the present invention will be described. The tandem printing system 1 receives a job sent from a terminal device such as a PC, and prints an image on paper, which is a print medium, based on the received job.

The tandem printing system 1 according to the first embodiment of the present invention is a printing system in which two printing devices are arranged in series along the paper transport path.

Figure 1 is a schematic diagram of a tandem printing system 1 according to a first embodiment of the present invention. As shown in Figure 1, the tandem printing system 1 according to the first embodiment includes a first printing device 10, an intermediate device 20, a second printing device 30, a discharge and reversing device 40, an overall control device 50, and a scanner 60.

In addition, in this embodiment, the first printing process and the second printing process are the same printing process, and the first printing device 10 performs the first printing process using CMYK color inks on one side of the paper, and the second printing device 30 performs the second printing process using functional inks on the same side of the paper printed by the first printing device 10. It is also possible for the first printing device 10 to perform the first printing process using CMYK color inks on one side of the paper, and the second printing device 30 to perform the second printing process using functional inks on the other side of the paper printed by the first printing device 10.

In addition, in FIG. 1, the path indicated by the thick line is the transport path along which the paper is transported. The transport path includes the transport path R1 in the first printing device 10, the transport path R2 in the intermediate device 20, the transport path R3 in the second printing device 30, and the transport path R4 in the discharge/reversal device 40. The transport path R1 in the first printing device 10 is a path that transports the paper to the second printing device 30 via the intermediate device 20, and when printing is performed only by the first printing device 10, it is switched to the transport path R1' and the paper is discharged to the paper discharge section 11P. The transport path R2 in the intermediate device 20 is a reversal path that reverses the paper, and when the paper does not need to be reversed, it is switched to the straight transport path R2' that transports the paper without reversing it. Furthermore, the transport path R4 in the discharge/reversal device 40 is a reversal path that reverses the paper, and when the paper does not need to be reversed, it is switched to the straight transport path R4' that transports the paper without reversing it, and the paper is discharged to the paper discharge tray 49.

As shown in FIG. 1, the first printing device 10 includes a transport unit 12, a printing unit 13, and a device control unit 15.

The transport unit 12 includes an external paper feed roller 12a and a registration roller 12b. The external paper feed roller 12a transports the paper P loaded on the paper feed tray 10P toward the registration roller 12b. The registration roller 12b temporarily stops the paper P transported from the external paper feed roller 12a, corrects the skew, and then sends it to the printing unit 13.

The printing unit 13 prints an image in color on the paper P while transporting the paper P. The printing unit 13 includes an ink head unit 13a, a belt transport unit 13b, and a paper discharge roller 13c.

The ink head unit 13a is disposed above the belt transport unit 13b and has multiple line-type inkjet heads with multiple nozzles arranged in a direction substantially perpendicular to the transport direction of the paper P. The ink head unit 13a prints an image by ejecting ink from the inkjet heads onto the paper P transported by the belt transport unit 13b. In this embodiment, the ink head unit 13a is equipped with inkjet heads capable of ejecting K ink (black ink), C ink (cyan ink), M ink (magenta ink), and Y ink (yellow ink). Of course, monochrome printing can also be performed using only K ink (black ink).

The belt conveying unit 13b conveys the paper P conveyed from the registration roller 12b by adsorbing and holding it on the belt. The belt conveying unit 13b is located downstream of the registration roller 12b and below the ink head unit 13a.

The paper discharge roller 13c discharges the paper P printed by the ink head unit 13a to the intermediate device 20.

The device control unit 15 controls various functions within the first printing device 10. The device control unit 15 controls the transport unit 12 and the printing unit 13 to print an image on the paper P.

The intermediate device 20 is disposed downstream in the transport direction from the first printing device 10. The intermediate device 20 transports the paper P discharged from the first printing device 10 to the second printing device 30. The intermediate device 20 includes a transport unit 22 and a device control unit 25.

The transport section 22 includes transport rollers 22a, 22b, and 22c, and transports the paper P along the transport path R2 or the straight transport path R2' using the transport rollers 22a, 22b, and 22c.

The device control unit 25 controls various functions of the intermediate device 20. The device control unit 25 controls the conveying unit 22 to convey the paper P while switching between the conveying path R2 and the straight conveying path R2'.

The second printing device 30 is disposed downstream of the intermediate device 20 in the conveying direction. The second printing device 30 includes a conveying unit 32, a printing unit 33, and a device control unit 35.

The transport unit 32 includes transport rollers 32a, which temporarily stop the paper P discharged from the intermediate device 20, correct the skew, and then transport it to the printing unit 33. The transport unit 32 also includes internal paper feed rollers 32c, which transport the paper P loaded in the paper feed tray 32P toward the printing unit 33.

The printing unit 33 prints an image on the paper P while transporting the paper P. The printing unit 33 includes an ink head unit 33a, a belt transport unit 33b, and a paper discharge roller 33c.

The ink head unit 33a is disposed above the belt transport unit 33b and has multiple line-type inkjet heads with multiple nozzles arranged in a direction substantially perpendicular to the transport direction of the paper P. The ink head unit 33a prints an image by ejecting functional ink from the inkjet heads onto the paper P transported by the belt transport unit 33b. In this embodiment, the ink head unit 33a is equipped with multiple inkjet heads capable of ejecting magnetic ink containing magnetic particles as the functional ink.

The configuration of the belt transport unit 33b is similar to that of the ink head unit 13a and belt transport unit 13b of the first printing device 10 described above, so a detailed description will be omitted.

The paper discharge roller 33c discharges the paper P printed by the ink head unit 33a to the discharge/reversal device 40.

The device control unit 35 controls various functions within the second printing device 30. The device control unit 35 controls the transport unit 32 and the printing unit 33 to print an image on the paper P.

The discharge/reversal device 40 is disposed downstream of the second printing device 30 in the transport direction. The discharge/reversal device 40 transports the paper P discharged from the second printing device 30 to the paper output tray 49. The discharge/reversal device 40 includes a transport unit 42 and a device control unit 45.

The transport section 42 includes transport rollers 42a, 42b, and 42c, and transports the paper P along the transport path R4 or the straight transport path R4' using the transport rollers 42a, 42b, and 42c.

The device control unit 45 controls various functions of the discharge/reversal device 40. The device control unit 45 controls the transport unit 42 to transport the paper P while switching between the transport path R4 and the straight transport path R4'.

The overall control device 50 controls various functions within the tandem printing system 1. The overall control device 50 also controls the first printing device 10, the intermediate device 20, the second printing device 30, and the discharge and reversing device 40 in an overall manner so as to execute printing processing based on a job.

The scanner 60 optically reads image data on the original and sends it to the overall control device 50. The scanner 60 obtains a specific chart image, for example, by scanning paper printed by the first printing device 10 and the second printing device 30 based on a specific chart for angle adjustment.

(Configuration of the overall control device 50)
Next, a specific description will be given of the configuration of the overall control device 50. Fig. 2 is a block diagram showing the functions of the tandem printing system 1.

As shown in FIG. 2, the overall control device 50 includes a job receiving unit 51, an acceptance unit 52, an adjustment angle calculation unit 53, a memory unit 56, and a communication unit 57.

The job receiving unit 51 transmits and receives information to and from the terminal device 100. Specifically, the job receiving unit 51 receives a job from the terminal device 100 used by the user. Note that the communication here may include, for example, an intranet (a corporate network) or a home network, and may be either wired communication or wireless communication.

The received job includes first image data used in the first print process by the first printing device 10 and second image data used in the second print process by the second printing device 30.

Figure 3(a) shows an example of the first image data and the second image data of a specific chart for angle adjustment included in a job.

As shown in FIG. 3(a), the specific chart is an image used to adjust the angle of the inkjet head of the ink head unit 33a, and includes first image data D1 and second image data D2.

The first image data D1 is image data used in the first printing process by the first printing device 10, and includes a straight line D11 along the direction of the nozzle row and a straight line D12 along the transport direction of the paper P. The second image data D2 is image data used in the second printing process by the second printing device 30, and includes a straight line D21 along the direction of the nozzle row and a straight line D22 along the transport direction of the paper P.

The reception unit 52 receives image data such as a specific chart image read by the scanner 60. For example, when the scanner 60 reads a sheet of paper P with a specific chart image printed on one side based on a job including the specific chart image by the first printing device 10 and the second printing device 30, the reception unit 52 receives the specific chart image read by the scanner 60.

Figures 3(b) and 3(c) show examples of specific chart images read by the scanner 60.

As shown in FIG. 3(b), the specific chart image that is read includes first image data D3 and second image data D4.

The first image data D3 is image data printed and read in the first printing process by the first printing device 10, and includes a straight line D31 along the direction of the nozzle row and a straight line D32 along the transport direction of the paper P. The second image data D4 is image data printed and read in the second printing process by the second printing device 30, and includes a straight line D41 along the direction of the nozzle row and a straight line D42 along the transport direction of the paper P.

As shown in FIG. 3(b), it can be seen that both the first image data D3 and the second image data D4 are printed with an upward sloping right-hand edge on the paper. This suggests that the inkjet heads of ink head unit 13a and ink head unit 33a are both tilted with their right-hand sides inclined toward the transport direction. It is assumed that the installation angle of the inkjet heads of ink head unit 13a is within the allowable angle range with respect to the nozzle direction. It is also assumed that the installation angle of the inkjet heads of ink head unit 33a is within the allowable angle range with respect to the nozzle direction.

In this case, even if the first image data D3 and the second image data D4 are printed on top of each other on one side of the paper P, the difference in the installation angle is small, so this does not pose a significant problem in the finished quality.

On the other hand, in the case shown in Figure 3(c), the quality of the finished product may be an issue.

As shown in FIG. 3(c), the specific chart image that is read includes first image data D5 and second image data D6.

The first image data D5 is image data printed and read in the first printing process by the first printing device 10, and includes a straight line D51 along the direction of the nozzle row and a straight line D52 along the transport direction of the paper P. The second image data D6 is image data printed and read in the second printing process by the second printing device 30, and includes a straight line D61 along the direction of the nozzle row and a straight line D62 along the transport direction of the paper P.

As shown in FIG. 3(c), the first image data D5 is printed with an upward sloping edge on the paper. On the other hand, the second image data D6 is printed with a downward sloping edge on the paper. This is presumably because the right side of the inkjet head of ink head unit 13a is inclined toward the transport direction, and the left side of the inkjet head of ink head unit 33a is inclined toward the transport direction.

The installation angle of the inkjet head of the ink head unit 13a is within the permissible angle range with respect to the nozzle direction. Also, the installation angle of the inkjet head of the ink head unit 33a is within the permissible angle range with respect to the nozzle direction.

In this case, if the first image data D5 and the second image data D5 are printed on top of each other on one side of the paper P, the difference in their installation angles may be large, which may cause problems with the finished quality.

Therefore, the adjustment angle calculation unit 53 calculates the adjustment angle of the inkjet head of the ink head unit 33a so that the finished quality is not an issue.

First, based on the specific chart image received by the reception unit 52, the adjustment angle calculation unit 53 calculates the installation angles of the inkjet heads (multiple first printing units) of the ink head unit 13a and the inkjet heads (multiple second printing units) of the ink head unit 33a relative to the transport direction from the straight lines printed in the transport direction of the paper P and the straight lines printed in the direction of the nozzle row.

In the example shown in FIG. 3(c), the adjustment angle calculation unit 53 calculates the installation angle of each of the inkjet heads (multiple first print units) of the ink head unit 13a relative to the transport direction from the straight lines D51 and D52. The adjustment angle calculation unit 53 also calculates the installation angle of each of the inkjet heads (multiple first print units) of the ink head unit 33a relative to the transport direction from the straight lines D61 and D62.

Next, the adjustment angle calculation unit 53 calculates the average of the calculated installation angles of each of the inkjet heads (multiple first printing units) of the ink head unit 13a as a first average angle. The adjustment angle calculation unit 53 also calculates the average of the calculated installation angles of each of the inkjet heads (multiple second printing units) of the ink head unit 33a as a second average angle.

Figure 4 shows an example of a specific chart image read by the scanner 60.

As shown in FIG. 4, the first image data E1 to E6 are image data printed and read in the first printing process by the first printing device 10, and the second image data F1 to EF are image data printed and read in the first printing process by the first printing device 10.

The adjustment angle calculation unit 53 calculates the average of the installation angles calculated based on each of the first image data E1 to E6 as the first average angle. The adjustment angle calculation unit 53 also calculates the average of the installation angles calculated based on each of the second image data F1 to F6 as the second average angle.

Then, the adjustment angle calculation unit 53 calculates the adjustment angle of the inkjet head (plurality of first print units) of the ink head unit 13a or the inkjet head (plurality of second print units) of the ink head unit 33a such that the second average angle relative to the calculated first average angle falls within a predetermined range. In other words, the adjustment angle calculation unit 53 calculates the adjustment angle such that the difference between the first average angle and the second average angle falls within the range.

The memory unit 56 stores the received job as a waiting job until the printing process is executed. When the waiting job is executed, the image data (first image data and second image data) to be printed by the first printing device 10 and the second printing device 30 are extracted and transmitted from the communication unit 57 to the printing device (the first printing device 10 or the second printing device 30). The memory unit 56 also stores the adjustment angle calculated by the adjustment angle calculation unit 53.

Figure 5 is a flowchart showing the processing steps of the tandem printing system 1 according to the first embodiment of the present invention.

As shown in FIG. 5, in step S101, the overall control device 50 controls the first printing device 10, the intermediate device 20, the second printing device 30, and the discharge and reversing device 40 to execute printing processing based on a job that includes a specific chart.

In step S103, the scanner 60 obtains a specific chart image by scanning the paper P printed by the first printing device 10 and the second printing device 30 based on the specific chart.

In step S105, the adjustment angle calculation unit 53 calculates the installation angles of the inkjet heads (multiple first printing units) of the ink head unit 13a and the inkjet heads (multiple second printing units) of the ink head unit 33a relative to the transport direction from the straight lines printed in the transport direction of the paper P and the straight lines printed in the direction of the nozzle row based on the specific chart image received by the reception unit 52.

In step S107, the adjustment angle calculation unit 53 calculates the average of the calculated installation angles of each of the inkjet heads (multiple first printing units) of the ink head unit 13a as a first average angle. The adjustment angle calculation unit 53 also calculates the average of the calculated installation angles of each of the inkjet heads (multiple second printing units) of the ink head unit 33a as a second average angle.

In step S109, the adjustment angle calculation unit 53 calculates the adjustment angle of the inkjet head (multiple first printing units) of the ink head unit 13a or the inkjet head (multiple second printing units) of the ink head unit 33a such that the second average angle relative to the calculated first average angle falls within a predetermined range.

In step S111, the adjustment angle calculation unit 53 determines whether the calculated adjustment angle is equal to or less than a predetermined threshold value.

If it is determined in step S111 that the adjustment angle is equal to or less than the predetermined threshold value (YES), the adjustment angle calculation unit 53 displays the adjustment angle on a display panel (not shown) (step S113), and the user adjusts the installation angle of the inkjet head (multiple first printing units) of the ink head unit 13a or the inkjet head (multiple second printing units) of the ink head unit 33a (step S115).

In this embodiment, the ink head unit 33a is configured to include an inkjet head capable of ejecting magnetic ink containing magnetic microparticles as functional ink, but this is not limited thereto. Similarly to the ink head unit 13a, the ink head unit 33a may be configured to include inkjet heads capable of ejecting K color ink, C color ink, M color ink, and Y color ink.

In addition, the ink head unit 33a may be equipped with an inkjet head capable of ejecting each of the special color inks such as gray, gold, and red, or may be equipped with an inkjet head capable of ejecting UV ink.

Note that the first printing device 10 and the second printing device 30 have been described as inkjet printing devices equipped with inkjet heads, but the printing section is not limited to this and may be other types of printing devices such as stencil printing devices or electrophotographic printing devices. In the case of an electrophotographic printing device, for example, when one printing device is in a situation where it cannot print with toner, the other printing device may print with toner, and then print when the other printing device becomes able to print with toner.

Furthermore, a combination of these is also possible. For example, the first printing device 10 may be an inkjet printing device and the second printing device 30 may be a stencil printing device.

(Additional Note)
This application discloses the following inventions.

(Appendix 1)
A printing system including a first printing device that prints on a transported sheet of paper based on a print job by ejecting ink from nozzle rows of a plurality of first printing units, and a second printing device that prints on the sheet of paper printed by the first printing device by ejecting ink from nozzle rows of a plurality of second printing units,
calculating an installation angle of each of the first printing units and the second printing units with respect to the transport direction from a straight line printed in the transport direction of the paper and a straight line printed in the direction of the nozzle array based on a specific chart image obtained by scanning a paper printed by the first printing device and the second printing device based on a specific chart for angle adjustment;
calculating an average angle of the plurality of first print units as a first average angle and an average angle of the plurality of second print units as a second average angle based on the calculated installation angles;
an adjustment angle calculation means for calculating an adjustment angle of the plurality of first printing units or the plurality of second printing units such that the second average angle relative to the calculated first average angle falls within a predetermined range.

As a result, even in a tandem printing system, it is possible to calculate an adjustment angle that keeps the difference between the first average angle and the second average angle within a range. For example, even if the first printing unit and the second printing unit are installed tilted in opposite directions, an appropriate adjustment angle can be calculated so that the quality of the finished print does not deteriorate. This makes it possible to keep the printing misalignment between the first printing device (upstream machine) and the first printing device (downstream machine) within an acceptable range. This makes it possible to prevent deterioration in the quality of the finished print.

1 Printing system 10 First printing device 13 Printing unit 13a Ink head unit 13b Belt transport unit 13c Paper discharge roller 15 Device control unit 20 Intermediate device 22 Transport unit 25 Device control unit 30 Second printing device 32 Transport unit 33 Printing unit 33a Ink head unit 33b Belt transport unit 35 Device control unit 40 Discharge/reversal device 42 Transport unit 45 Device control unit 50 Overall control device 51 Job receiving unit 52 Acceptance unit 53 Adjustment angle calculation unit 56 Memory unit 57 Communication unit 60 Scanner 100 Terminal device

Claims (1)

A printing system including a first printing device that prints on a transported sheet of paper based on a print job by ejecting ink from nozzle rows of a plurality of first printing units, and a second printing device that prints on the sheet of paper printed by the first printing device by ejecting ink from nozzle rows of a plurality of second printing units,
calculating an installation angle of each of the first printing units and the second printing units with respect to the transport direction from a straight line printed in the transport direction of the paper and a straight line printed in the direction of the nozzle array based on a specific chart image obtained by scanning a paper printed by the first printing device and the second printing device based on a specific chart for angle adjustment;
calculating an average angle of the plurality of first print units as a first average angle and an average angle of the plurality of second print units as a second average angle based on the calculated installation angles;
an adjustment angle calculation means for calculating an adjustment angle of the plurality of first printing units or the plurality of second printing units such that the second average angle relative to the calculated first average angle falls within a predetermined range.

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