JP2019147675A - Double-side printing system - Google Patents

Abstract

To prevent paper jams even if a printing speed of a downstream image forming apparatus is slow, papers being discharged in series.SOLUTION: A double-side printing system includes: an acquisition unit 43 that acquires a resolution and a density of each of first image data and second image data included in a double-side printing job; a calculation unit 44 that calculates a first conveyance speed V1 for a conveyance on a conveyance path of an upstream printing apparatus 10, and a second conveyance speed V2 for a conveyance on a conveyance path of a downstream printing apparatus 30, based on a resolution and a density acquired by the acquisition unit 43; and a correction unit 45 that corrects a paper feed timing at which the upstream printing apparatus 10 starts conveying paper on the conveyance path, so that a paper P conveyed from the upstream printing apparatus 10 to the downstream printing apparatus 30 does not come into contact with a paper P conveyed in a second printing cycle, when the second conveyance speed V2 is less than the first conveyance speed V1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a duplex printing system that performs duplex printing on paper.

  Conventionally, a circulation conveyance path including a sheet reversing path has been provided, and printing is performed on one side of a sheet fed from a sheet feeding table, and the sheet printed on this one side is conveyed on the sheet reversing path. There is a double-sided printing apparatus that performs double-sided printing by reversing the front and back and printing on the other side (for example, Patent Document 1).

  In such a double-sided printing apparatus, the paper fed from the paper feed tray and the paper that has been turned upside down by the paper reversing path are alternately conveyed, so the printing time is longer than when printing on one side. It was.

  Therefore, as in Patent Document 2, the first image forming unit and the second image forming unit are arranged in series, and the first image forming unit performs printing on one side of the sheet conveyed along the conveyance path. A technology relating to a tandem ink jet recording apparatus that reverses the front and back of the paper by a reversing device and transports the paper to the second image forming unit and performs printing on the other surface of the paper transported through the transport path by the second image forming unit. It is disclosed.

JP 2014-91304 A JP 2011-51342 A

  When printing by the image forming unit, the printing speed varies depending on the resolution and density of the image data. Therefore, it is necessary to control the conveyance speed of the paper conveyed on the conveyance path by this printing speed.

  Here, the resolution and density of the image data for printing on one side of the paper and the image data for printing on the other side may differ.

  In the tandem inkjet recording apparatus of Patent Document 2, the first image forming unit and the second image forming unit are arranged in series, so that the printing speed in the second image forming unit is higher than the printing speed in the first image forming unit. If the sheet is late, there is a possibility that the paper that is reversed by the reversing device and conveyed to the second image forming unit and the paper printed by the second image forming unit come into contact with each other to cause a paper jam.

  SUMMARY An advantage of some aspects of the invention is that it provides a double-sided printing system capable of preventing a paper jam.

In order to achieve the above object, the feature of the duplex printing system according to the present invention is as follows:
An upstream printing apparatus that executes a printing process on one side of a sheet conveyed on a conveyance path in a first printing cycle based on first image data included in the print job, and a printing process performed by the upstream printing apparatus A downstream printing apparatus that executes a printing process on the other surface of the sheet conveyed on the conveyance path in a second printing cycle based on the second image data included in the print job. A duplex printing system that performs duplex printing using
Acquisition means for acquiring the resolution and density of each of the first image data and the second image data included in the print job;
Based on the resolution and density acquired by the acquisition means, a first transport speed for transporting on the transport path of the upstream printing apparatus and a second transport speed for transporting on the transport path of the downstream printing apparatus are calculated. A calculation means;
When the second transport speed is less than the first transport speed, the upstream sheet is transported so that the sheet transported from the upstream printing apparatus to the downstream printing apparatus does not contact the sheet transported in the second printing cycle. And a positive means for correcting the paper feed timing at which the side printing apparatus starts transporting the paper on the transport path.

  According to the feature of the duplex printing system according to the present invention, it is possible to prevent a paper jam.

1 is a schematic configuration diagram of a double-sided printing system according to a first embodiment of the present invention. It is a block diagram which shows the function of the double-sided printing system which concerns on 1st Embodiment of this invention. It is the flowchart which showed the processing content of the control in 1 pass printing in the double-sided printing system which concerns on 1st Embodiment of this invention. FIG. 4A is a timing chart showing a conventional printing schedule, and FIG. 4B is a timing chart showing a printing schedule according to the first embodiment of the present invention. It is a block diagram which shows the function of the double-sided printing system which concerns on 2nd Embodiment of this invention. It is the flowchart which showed the processing content of the control in 2 pass printing in the double-sided printing system which concerns on 2nd Embodiment of this invention. It is the flowchart which showed the processing content of the control in 2 pass printing in the double-sided printing system which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of the double-sided printing system 1 according to the first embodiment of the present invention will be described. The duplex printing system 1 receives a duplex printing job transmitted from a terminal device such as a PC, and prints an image on a sheet as a printing medium based on the received duplex printing job.

  The double-sided printing system 1 according to the present embodiment is a printing system having a configuration in which two printing apparatuses each performing predetermined printing processing on a sheet are arranged in series along a sheet conveyance path.

  Here, FIG. 1 is a schematic configuration diagram of a duplex printing system 1 according to the first embodiment of the present invention. As shown in FIG. 1, the duplex printing system 1 according to the first embodiment includes an upstream printing device 10, an intermediate device 20, a downstream printing device 30, and an overall control device 40.

  In the present embodiment, the predetermined printing process is a process for completing the printing of the requested image, and the upstream printing apparatus 10 executes the predetermined printing process on one side of the paper, The downstream printing apparatus 30 performs a printing process on the other side of the paper. The predetermined printing process includes monochrome printing or color printing process.

  In FIG. 1, a path indicated by a double line or a thick line is a conveyance path through which the sheet is conveyed. The conveyance path includes a conveyance path R1 in the upstream printing apparatus 10, a conveyance path R2 in the intermediate apparatus 20, and a conveyance path R3 in the downstream printing apparatus 30.

  As shown in FIG. 1, the upstream printing apparatus 10 includes a side paper feed unit 110, an internal paper feed unit 120, a printing unit 130, a paper discharge unit 140, and a reversing unit 150.

  The side paper feed unit 110 includes a paper feed tray 111 on which the paper P is stacked, a pickup roller 112 that transports only the uppermost paper P from the paper feed base 111 onto the paper feed transport path FR1, and the pickup roller 112. And a registration roller 114 for carrying the skew correction by temporarily slackening the paper P conveyed by, and then conveying it onto the circulation conveyance path CR1. A time interval from the time when the registration roller 114 conveys the paper P onto the circulation conveyance path CR1 to the time when the next paper P is conveyed onto the circulation conveyance path CR1 is referred to as a first printing cycle.

  The internal paper feed unit 120 includes paper feed trays 121a to 121d on which the paper P is stacked, and pickup rollers 122a to 122d that transport only the uppermost paper P from the paper feed stands 121a to 121d onto the paper feed transport path FR1. And.

  Further, an intermediate conveyance roller 123 that conveys the paper P conveyed from the pickup rollers 122a to 122d onto the paper feed conveyance path FR1 to the registration roller 114 on the paper feed conveyance path FR1 is provided.

  In this way, the sheet P is conveyed to the registration roller 114 from the pickup roller 112 of the side paper feeding unit 110 and the intermediate conveyance roller 123 of the internal paper feeding unit 120, and also from a conveyance roller 153 of the reversing unit 150 described later. The paper P is transported, and after the transported paper P is slackened, skew correction is performed, and then transported onto the circulation transport path CR1.

  Therefore, a junction point where the conveyance path of the fed paper P and the path through which the paper on which one side is printed is circulated is merged exists in front of the registration roller 114 in the conveyance direction. . Based on this merging point, the path on the sheet feeding mechanism side is referred to as a sheet feeding conveyance path FR1, and the other path is referred to as a circulation conveyance path CR1.

  The printing unit 130 includes an inkjet head unit 134 in which a plurality of print heads are incorporated, and an annular conveyance belt 133 provided on the opposite surface of the inkjet head unit 134, and is a sheet fed by a registration roller 114. P is sucked onto the conveying belt 133 by the suction fans 131 and 132 installed in the annular conveying belt 133 corresponding to the back surface of the sheet conveying path, and is conveyed at the first conveying speed V1, while being an inkjet head. Printing is performed on the paper P by the ink ejected from the unit 134. Further, a paper sensor 137 that detects the paper P conveyed by the conveyance belt 133 is provided in the vicinity of the upstream side of the inkjet head unit 134.

  The paper P printed by the printing unit 130 is conveyed on the circulation conveyance path CR1 in the housing by a conveyance roller disposed on the circulation conveyance path CR1. A switching mechanism 135 is provided on the circulation conveyance path CR1 to switch whether the paper P conveyed on the circulation conveyance path CR1 is guided to the intermediate apparatus 20 or recirculated on the circulation conveyance path CR1. Further, a switching mechanism 143 is provided for switching between guiding the sheet P conveyed on the circulation conveyance path CR1 to the paper discharge unit 140 or recirculating on the circulation conveyance path CR1. The circulation conveyance path CR1 is provided with sheet sensors 138 and 139 for detecting sheets conveyed on the circulation conveyance path CR1.

  The paper discharge unit 140 includes a tray-shaped paper discharge table 141 protruding from the casing of the upstream printing apparatus 10 and a pair of paper discharge rollers 142 that guide the paper P to the paper discharge table 141. Then, the paper P guided to the paper discharge unit 140 by the switching mechanism 143 is conveyed and stacked on the paper discharge table 141 by the paper discharge roller 142.

  The reversing unit 150 reverses the reversing table 151 that reverses the paper P, and the reversing roller 152 that conveys the paper P from the reversing conveyance path CR1 to the reversing reversing table 151, or conveys the paper P from the reversing stand 151 onto the recirculating conveying path CR1. It has.

  The sheet P guided to the reversing unit 150 by the switching mechanism 143 is conveyed from the circulation conveyance path CR1 to the reversing table 151 by the reversing roller 152, and is conveyed from the reversing table 151 to the circulation conveyance path CR1 after a predetermined time. The front and back are reversed with respect to the circulation conveyance path CR1. The sheet P with the front and back reversed is conveyed toward the printing unit 130 on the circulation conveyance path CR1 by a plurality of rollers such as a conveyance roller 153 provided on the circulation conveyance path CR1.

  The device control unit 160 controls the side paper feed unit 110, the internal paper feed unit 120, the printing unit 130, the paper discharge unit 140, and the reversing unit 150 in accordance with an instruction from the overall control device 40 described later. An image is printed on the paper P, and the printed paper P is conveyed to the intermediate device 20 or discharged onto the paper discharge table 141.

  The intermediate device 20 is disposed on the downstream side in the transport direction of the upstream printing device 10. The intermediate device 20 reverses the front and back of the paper P carried out from the upstream printing device 10 and then conveys the paper P to the downstream printing device 30. The intermediate device 20 includes a transport unit 210 and a device control unit 260.

  The transport unit 210 includes transport rollers 211, 212, and 213, and transports the paper P along the transport path R2 by driving the transport rollers 211, 212, and 213.

  The device control unit 260 controls various functions of the intermediate device 20. As a result, when the paper P is transported to a predetermined position on the transport path R <b> 2, the transport roller 212 is reversely rotated by the reverse rotation and transported to the downstream printing apparatus 30 by the transport roller 213. Further, an intermediate paper discharge table 221 is provided at the end of the transport path R2.

  The downstream printing apparatus 30 includes an intermediate conveyance unit 310, an internal paper feeding unit 320, a printing unit 330, a paper discharge unit 340, and a reversing unit 350.

  The intermediate transport unit 310 includes a registration roller 314 that performs skew correction by temporarily loosening the transported paper P and then transports the transported paper P onto the circulation transport path CR3. A time interval from the time when the registration roller 314 transports the paper P onto the circulation transport path CR3 to the time when the next paper P is transported onto the circulation transport path CR3 is referred to as a second printing cycle.

  The internal paper feed unit 320 includes paper feed bases 321a to 321d on which the paper P is stacked, and pickup rollers 322a to 322d that transport only the uppermost paper P from the paper feed bases 321a to 321d onto the paper feed transport path FR3. And.

  Then, an intermediate transport roller 323 is provided that transports the paper P transported from the pickup rollers 322a to 322d onto the paper feed transport path FR3 to the registration roller 314 on the paper feed transport path FR3.

  As described above, the sheet P is transported to the registration roller 314 from the intermediate transport roller 323 of the internal paper feeding unit 320, and further, the paper P is transported from the transport roller 353 of the reversing unit 350 described later. After skew correction is performed by temporarily loosening P, the sheet is conveyed onto the circulation conveyance path CR3.

  Therefore, a junction point where the conveyance path of the fed paper P and the path through which the paper on which one side is printed is circulated is merged exists in front of the registration roller 314 in the conveyance direction. . Based on this merging point, the path on the sheet feeding mechanism side is referred to as a sheet feeding conveyance path FR3, and the other path is referred to as a circulation conveyance path CR3. In the downstream printing apparatus 30, since the paper P is transported from the intermediate apparatus 20, the internal paper feed unit 320 and the paper feed transport path FR <b> 3 are not necessarily provided, and only the downstream printing apparatus 30 is used. Used for printing.

  The printing unit 330 includes an ink jet head unit 334 in which a plurality of print heads are incorporated, and an annular conveyance belt 333 provided on the opposite surface of the ink jet head unit 334, and paper fed by a registration roller 314. P is sucked onto the conveyance belt 333 by the suction fans 331 and 332 installed in the annular conveyance belt 333 corresponding to the back surface of the sheet conveyance path, and is conveyed at the second conveyance speed V2 while being an inkjet head. Printing is performed on the paper P by the ink ejected from the unit 334. A paper sensor 337 that detects the paper P conveyed by the conveyance belt 333 is provided in the vicinity of the upstream side of the inkjet head unit 334.

  The paper P printed by the printing unit 330 is conveyed on the circulation conveyance path CR3 in the housing by a conveyance roller disposed on the circulation conveyance path CR3. On the circulation conveyance path CR3, the sheet P conveyed on the circulation conveyance path CR3 is discharged to a tray-shaped sheet discharge tray 345 protruding from the casing of the downstream printing apparatus 30, or the circulation conveyance path A switching mechanism 335 that switches whether to recirculate on the CR3 is provided. In addition, a switching mechanism 343 that switches between guiding the sheet P conveyed on the circulation conveyance path CR3 to the paper discharge unit 340 or recirculating on the circulation conveyance path CR3 is provided. In the circulation conveyance path CR3, sheet sensors 338 and 339 for detecting sheets conveyed on the circulation conveyance path CR3 are provided.

  The paper discharge unit 340 includes a tray-shaped paper discharge table 341 protruding from the casing of the downstream printing apparatus 30 and a pair of paper discharge rollers 342 that guide the paper P to the paper discharge table 341. The paper P guided to the paper discharge unit 340 by the switching mechanism 343 is transported to the paper discharge table 341 by the paper discharge roller 342 and stacked.

  The reversing unit 350 includes a reversing table 351 for reversing the paper P, and a reversing roller 352 that transports the paper P from the circulation conveyance path CR3 to the reversing table 351 or conveys the paper P from the reversing table 351 onto the circulation conveyance path CR3. It has.

  The sheet P guided to the reversing unit 350 by the switching mechanism 343 is conveyed from the circulation conveyance path CR3 to the reversing table 351 by the reversing roller 352, and is conveyed from the reversing table 351 to the circulation conveyance path CR3 after a predetermined time. The front and back are reversed with respect to the circulation conveyance path CR3. The sheet P with the front and back reversed is conveyed toward the printing unit 330 on the circulation conveyance path CR3 by a plurality of rollers such as a conveyance roller 353 provided on the circulation conveyance path CR3.

  The device control unit 360 controls the intermediate conveyance unit 310, the internal paper feeding unit 320, the printing unit 330, the paper discharge unit 340, and the reversing unit 350 in accordance with instructions from the overall control device 40, which will be described later. In addition to printing an image on P, the printed paper P is discharged onto a discharge tray 341 or discharged onto a discharge tray 345.

  The overall control device 40 controls various functions in the duplex printing system 1. The overall control apparatus 40 controls the upstream printing apparatus 10, the intermediate apparatus 20, and the downstream printing apparatus 30 so as to execute a printing process based on the double-sided print job.

(Schematic operation of the duplex printing system)
In the double-sided printing system 1, the upstream printing device 10 and the downstream printing device 30 each perform double-sided printing by printing once with the inkjet head unit (one-pass printing), and twice with each inkjet head unit. There is a case where double-sided printing is performed by printing two by two (two-pass printing). Single-sided duplex setting information for specifying whether to perform single-sided printing (one-pass printing) or double-sided printing (two-pass printing) is included in the duplex printing job. Here, each of 1-pass printing and 2-pass printing will be described.

<1-pass printing>
In the one-pass printing, when the paper P is fed from the side paper feeding unit 110 or the internal paper feeding unit 120, the paper is conveyed by the registration roller 114 onto the circulation conveyance path CR1 at intervals of the first printing cycle, and then the conveyance belt. The ink is ejected from the inkjet head unit 134 while being conveyed at the first conveyance speed V <b> 1 by 133, and is printed on the surface of the paper P.

  The paper P on which the front surface is printed is guided to the intermediate device 20 by the switching mechanism 135.

  The intermediate device 20 reverses the front and back of the paper P carried out from the upstream printing device 10 and then conveys the paper P to the downstream printing device 30.

  In the downstream printing apparatus 30, the sheet is conveyed by the registration roller 314 onto the circulation conveyance path CR 3 at intervals of the second printing cycle, and then discharged from the inkjet head unit 334 while being conveyed by the conveyance belt 333 at the second conveyance speed V 2. The ink is printed on the back surface of the paper P with the ink. Then, the paper P printed on the back surface is discharged to the paper discharge tray 345 by the switching mechanism 335.

  As described above, in the case of performing one-pass printing, the inkjet head unit 134 and the inkjet head unit 334 often use the same ink.

<2-pass printing>
In the two-pass printing, when the paper P is fed from the side paper feeding unit 110 or the internal paper feeding unit 120, the paper is conveyed by the registration rollers 114 onto the circulation conveyance path CR1 at intervals of the first printing cycle, and then the conveyance belt. The ink is ejected from the inkjet head unit 134 while being conveyed at the first conveyance speed V <b> 1 by 133, and is printed on the surface of the paper P.

  The sheet P on which the front surface is printed is recirculated on the circulation conveyance path CR1 by switching the switching mechanism 135. The recirculated paper P is reversed by the reversing unit 150. The sheet P with the front and back reversed is conveyed toward the printing unit 130 by a plurality of rollers such as a conveyance roller 153. Then, after the paper P is transported on the circulation transport path CR1 by the registration rollers 114 at intervals of the first printing cycle, the paper P is discharged from the inkjet head unit 134 while being transported by the transport belt 133 at the first transport speed V1. Printed on the back side with ink.

  The sheet P on which both sides are printed is conveyed to the downstream printing apparatus 30 after the front and back sides are reversed by the intermediate apparatus 20.

  The sheet P transported to the downstream printing apparatus 30 is transported onto the circulation transport path CR3 by the registration rollers 314 at intervals of the second printing cycle. Thereafter, printing is performed on the surface again by the ink ejected from the inkjet head unit 334 while being transported by the transport belt 333 at the second transport speed V2.

  The sheet P on which the front surface is printed is recirculated on the circulation conveyance path CR3 by switching the switching mechanism 335. The recycled paper P is reversed by the reversing unit 350. The paper P with the front and back reversed is conveyed toward the printing unit 330 by a plurality of rollers such as a conveyance roller 353. The paper P was transported on the circulation transport path CR3 at intervals of the second printing cycle by the registration rollers 314, and then discharged from the inkjet head unit 334 while being transported at the second transport speed V2 by the transport belt 333. Printed on the back side with ink. Then, the paper P printed on the back surface is discharged to the paper discharge tray 345 by the switching mechanism 335.

  In this way, when performing two-pass printing, the inkjet head unit 134 and the inkjet head unit 334 often use different inks. For example, ink such as C (cyan), M (magenta), Y (yellow), and K (black) is used for the ink jet head unit 134, and the ink jet head unit 334 has functions such as intermediate color ink and invisible ink. Ink is used.

  In the two-pass printing, either one of the upstream printing apparatus 10 and the downstream printing apparatus 30 may perform single-sided printing and the other may perform double-sided printing. For example, the upstream printing apparatus 10 may perform single-side printing on the front surface, and the downstream printing apparatus 30 may perform double-side printing on the front and back surfaces. Alternatively, the upstream printing apparatus 10 may perform double-side printing on the front and back surfaces. Alternatively, one-side printing on the front surface may be performed by the downstream printing apparatus 30.

(Configuration of overall control device 40)
Next, the configuration of the overall control device 40 will be specifically described. FIG. 2 is a block diagram illustrating functions of the duplex printing system 1.

  As shown in FIG. 2, the overall control device 40 includes a job reception unit 41, a job division unit 42, an acquisition unit 43, a calculation unit 44, a correction unit 45, and a communication unit 47.

  The job receiving unit 41 transmits / receives information to / from the terminal device 100. Specifically, the job receiving unit 41 receives a print job (double-sided print job) from the terminal device 100 used by the user. The communication here includes, for example, an intranet (in-house network), a home network, and the like, and may be either wired communication or wireless communication.

  Upon receiving a duplex printing job from the terminal device 100, the job dividing unit 42 prints image data (first image data) to be printed by the upstream printing apparatus 10 and printing by the downstream printing apparatus 30 from the received duplex printing job. The image data is divided into image data (second image data) to be processed.

  The printing speed by the inkjet head unit varies depending on the resolution and density of the image data. Therefore, it is necessary to determine the first transport speed V1 and the second transport speed V2 according to the printing speed.

  Therefore, the acquisition unit 43 acquires the resolution and density of each of the first image data and the second image data from the print setting information included in the double-sided print job.

  The calculation unit 44 has a first conveyance speed V1 conveyed by the conveyance belt 133 of the upstream printing apparatus 10 based on the resolution and density of each of the first image data and the second image data acquired by the acquisition unit 43, and A second transport speed V2 transported by the transport belt 333 of the downstream printing apparatus 30 is calculated.

  The correction unit 45 determines whether or not the second transport speed V2 calculated by the calculation unit 44 is less than the first transport speed V1. When the second transport speed V2 is less than the first transport speed V1, when printing is performed as it is in the first printing cycle, the sheet P is reversed by the intermediate apparatus 20 and transported to the downstream printing apparatus 30, and the downstream printing apparatus There is a possibility that the paper P printed by the paper 30 will come into contact and paper jam will occur.

  Accordingly, the correction unit 45 changes the sheet P conveyed from the intermediate apparatus 20 to the downstream printing apparatus 30 to the sheet P conveyed in the second printing cycle when the second conveyance speed V2 is less than the first conveyance speed V1. In order to avoid contact, the paper feed timing at which the registration roller 114 determined by the first printing cycle transports the paper P onto the circulation transport path CR1 is corrected.

  The communication unit 47 transmits and receives various types of information to and from the upstream printing apparatus 10, the intermediate apparatus 20, and the downstream printing apparatus 30.

<Operation of duplex printing system 1>
Next, the operation of “control in one-pass printing” in the duplex printing system 1 according to the first embodiment of the present invention will be described. The operation of “control in two-pass printing” will be described in the second embodiment.

  As shown in FIG. 3, when the overall control device 40 receives a duplex printing job from the terminal device 100 (step S101), the job dividing unit 42 extracts image data from the received duplex printing job, and the extracted image data Are divided into first image data to be printed by the upstream printing apparatus 10 and second image data to be printed by the downstream printing apparatus 30 (step S103). Here, in the 1-pass printing, the upstream printing apparatus 10 prints the front surface (one surface) and the downstream printing device 30 prints the back surface (the other surface), so double-sided printing is performed. Assigns the image data of the front surface as the first image data and the image data of the back surface as the second image data.

  Next, the acquisition unit 43 acquires the resolution and density of each of the first image data and the second image data, and the paper size from the print setting information included in the double-sided print job (step S105).

  Then, the calculation unit 44 calculates the first conveyance speed V1 conveyed by the conveyance belt 133 of the upstream printing apparatus 10 based on the resolution and density of the first image data acquired by the acquisition unit 43 (Step S107). ). Further, the calculation unit 44 calculates the second conveyance speed V2 conveyed by the conveyance belt 333 of the downstream printing apparatus 30 based on the resolution and density of the second image data acquired by the acquisition unit 43 (step S109). ).

  Next, the calculation unit 44 calculates a reference sheet interval (step S111). The reference sheet interval is determined based on the sheet size included in the print setting information. Since the upstream printing apparatus 10 and the downstream printing apparatus 30 print on the same sheet P, the reference sheet interval is common to the upstream printing apparatus 10 and the downstream printing apparatus 30.

  Then, the correcting unit 45 sets the first print cycle and the second print cycle based on the paper size and the reference paper interval (step S113). Specifically, the correction unit 45 sets the first print cycle by dividing the length obtained by adding the reference sheet interval to the length in the transport direction of the paper P by the first transport speed V1, and also the paper A length obtained by adding the reference sheet interval to the length in the transport direction of P is divided by the second transport speed V2 to set the second print cycle.

  Then, the correction unit 45 determines whether or not the second conveyance speed V2 calculated by the calculation unit 44 is less than the first conveyance speed V1 (step S115).

  When the second conveyance speed V2 is equal to or higher than the first conveyance speed V1 (step S115; NO), it is assumed that printing is performed in the first printing cycle in the upstream printing apparatus 10 and printing is performed in the second printing cycle in the downstream printing apparatus 30. However, the paper P that is turned upside down by the intermediate device 20 and conveyed to the downstream printing device 30 does not come into contact with the paper P printed by the downstream printing device 30 to cause a paper jam.

  Therefore, the overall control device 40 prints the front surface (one surface) with the upstream printing apparatus 10 based on the first printing cycle set in step S113, and based on the second printing cycle set in step S113. Then, the apparatus control units 160, 260, and 360 are instructed to start double-sided printing for printing the back surface (the other surface) with the downstream printing device 30 (step S121).

  On the other hand, when the second transport speed V2 is less than the first transport speed V1 (step S115; YES), the upstream printing apparatus 10 performs printing in the first printing cycle, and the downstream printing apparatus 30 performs printing in the second printing cycle. Then, there is a possibility that the paper P that is reversed by the intermediate device 20 and conveyed to the downstream printing device 30 and the paper P printed by the downstream printing device 30 come into contact with each other to cause a paper jam.

  Accordingly, the correction unit 45 calculates a correction value CV1 for correcting the paper feed timing at which the registration roller 114 determined by the first printing cycle transports the paper P onto the circulation transport path CR1 so that the paper P does not contact. (Step S117). Specifically, the correction unit 45 calculates the correction value CV1 using the following (Equation 1), where LP is the length in the transport direction of the paper P and LS is the reference paper interval.

CV1 = (LP + LS) × (1 / V2-1 / V1) (Formula 1)
Then, the correction unit 45 adds the calculated correction value CV1 to the first printing cycle set in step S113 to newly set the first printing cycle, so that the registration roller 114 is placed on the circulation conveyance path CR1. The paper feed timing for transporting the paper P to the paper is corrected (step S119).

  The overall control device 40 prints the front surface (one surface) with the upstream printing apparatus 10 based on the paper feed timing corrected in step S119, and the paper feed timing based on the second print cycle set in step S113. Thus, the apparatus control units 160, 260, and 360 are instructed to start double-sided printing for printing the back surface (the other surface) by the downstream printing device 30 (step S121).

  FIG. 4 is a diagram for explaining the effect of the duplex printing system 1 according to the first embodiment of the present invention. FIG. 4A is a timing chart showing a conventional printing schedule, and FIG. 4B is a timing chart showing a printing schedule according to the first embodiment of the present invention. Here, it is assumed that the second transport speed V2 is less than the first transport speed V1.

  As shown in FIG. 4A, conventionally, at the time point t1, the upstream side printing apparatus 10 transports the sheet P (P1) by the registration roller 114, and the surface is printed. The sheet P (P1) on which the front surface is printed is conveyed to the intermediate device 20 at time t2 when the first printing cycle has elapsed from time t1. In the upstream printing apparatus 10, the next sheet P (P2) is conveyed by the registration roller 114 at time t2, and the front surface is printed.

  The sheet P (P1) transported to the intermediate device 20 at time t2 is turned upside down and transported to the downstream printing device 30 at time t3, and the paper P (P1) is transferred by the registration roller 314 in the downstream printing device 30. It is conveyed and the back side is printed.

  At this time, the paper P (P2) for which printing has started from time t2 is conveyed to the intermediate device 20 at time t4, and is conveyed to the downstream printing device 30 at time t5. At time t5, since the downstream side printing apparatus 30 is printing the previous sheet P (P1), there is a possibility that the sheet P (P1) and the sheet P (P2) collide and a paper jam occurs. is there.

  On the other hand, in the first embodiment of the present invention, as shown in FIG. 4B, the sheet P (P1) is transported by the registration roller 114 in the upstream printing apparatus 10 at time t11, and the surface is printed. The paper P (P1) on which the front surface is printed is conveyed to the intermediate device 20 at time t12. In the upstream side printing apparatus 10, the next sheet P (P2) is conveyed by the registration roller 114 at time t14 after the first printing cycle corrected by the correction unit 45, and the surface is printed.

  The sheet P (P1) transported to the intermediate device 20 at time t12 is turned upside down and transported to the downstream printing device 30 at time t13, and the paper P (P1) is transferred by the registration rollers 314 in the downstream printing device 30. It is conveyed and the back side is printed.

  The paper P (P2) for which printing has started from time t14 is transported to the intermediate device 20 at time t15, and is transported to the downstream printing device 30 at time t16. Since the second printing cycle has passed at time t16, the previous paper P (P1) is discharged. Therefore, even if the paper P (P2) is transported to the downstream printing apparatus 30 at time t16, the paper P (P1) and the paper P (P2) do not collide. Thereby, it is possible to prevent a paper jam from occurring.

  As described above, according to the duplex printing system 1 according to the first embodiment of the present invention, the acquisition unit 43 acquires the resolution and density of the first image data and the second image data included in the duplex printing job. Then, the calculation unit 44 calculates the first transport speed V1 and the second transport speed V2 based on the resolution and density acquired by the acquisition unit 43, and the correction unit 45 sets the second transport speed V2 to the first. When the conveyance speed is less than V1, the first printing is performed so that the sheet conveyed from the upstream printing apparatus 10 to the downstream printing apparatus 30 via the intermediate apparatus 20 does not contact the sheet P conveyed in the second printing cycle. The upstream printing apparatus 10 determined by the cycle corrects the paper feed timing at which the paper starts to be transported on the transport path.

  Therefore, even when the second transport speed V2 is lower than the first transport speed V1, the paper P printed by the upstream printing apparatus 10 and reversed by the intermediate apparatus 20 and transported to the downstream printing apparatus 30 The upstream printing apparatus 10 sets an appropriate first printing cycle so that the paper P printed by the downstream printing apparatus 30 does not come into contact, and performs printing in this first printing cycle. Therefore, it is possible to prevent a paper jam due to the contact of the paper P.

  Further, the correction unit 45 calculates a correction value CV1 based on the length LP in the transport direction of the paper P, the first transport speed V1, and the second transport speed V2, and the first correction based on the calculated correction value CV1. Since the paper feed timing determined by one printing cycle is corrected, the paper feed timing can be corrected more accurately.

[Second Embodiment]
In the first embodiment of the present invention, the overall control device 40 includes a job receiving unit 41, a job dividing unit 42, an acquiring unit 43, a calculating unit 44, a correcting unit 45, and a communication unit 47. However, the present invention is not limited to this, and the upstream printing apparatus 10 or the downstream printing apparatus 30 may have these configurations.

  In the second embodiment of the present invention, an example in which the device control unit 160 of the upstream printing apparatus 10 and the device control unit 360 of the downstream printing apparatus 30 have these configurations will be described.

  FIG. 5 is a block diagram showing functions of the duplex printing system 1 according to the second embodiment of the present invention. The hardware configuration of the duplex printing system 1 according to the second embodiment of the present invention is the same as the schematic configuration diagram of the duplex printing system 1 according to the first embodiment of the present invention shown in FIG. Is omitted.

  As shown in FIG. 5, the overall control device 40 includes a job receiving unit 41, a job dividing unit 42, and a communication unit 47. Since these structures are the same as those shown in FIG.

  The apparatus control unit 160 of the upstream printing apparatus 10 includes a communication unit 161, an acquisition unit 163, a calculation unit 164, and a correction unit 165.

  The communication unit 161 transmits and receives information to and from the overall control device 40, the intermediate device 20, and the downstream printing device 30. Specifically, the communication unit 161 receives the first image data or receives the second transport speed V2 from the downstream printing apparatus 30. The communication here includes, for example, an intranet (in-house network), a home network, and the like, and may be either wired communication or wireless communication.

  The acquisition unit 163 acquires the resolution and density from the received first image data, and acquires the paper size and single-sided duplex setting from the overall control device 40. Note that the acquisition unit 163 may directly acquire the resolution, density, paper size, and single-sided duplex setting of the first image data from the overall control device 40.

  The calculation unit 164 calculates the first conveyance speed V1 conveyed by the conveyance belt 133 of the upstream printing apparatus 10 based on the resolution and density of the first image data acquired by the acquisition unit 163.

  When receiving the second transport speed V <b> 2 from the downstream printing apparatus 30, the correction unit 165 determines whether the received second transport speed V <b> 2 is less than the first transport speed V <b> 1 calculated by the calculation unit 164. When the second transport speed V2 is less than the first transport speed V1, the paper P transported from the intermediate device 20 to the downstream printing device 30 does not come into contact with the paper P transported in the second printing cycle. The upstream printing apparatus 10 determined by the first printing cycle corrects the paper feed timing at which the paper starts to be transported on the transport path.

<Operation of duplex printing system 1>
Next, the operation of “control in two-pass printing” in the duplex printing system 1 according to the second embodiment of the present invention will be described.

  As illustrated in FIG. 6, when the overall control apparatus 40 receives a double-sided print job from the terminal apparatus 100 (step S201), the job dividing unit 42 extracts image data from the received double-sided print job, and the extracted image data Are divided into first image data to be printed by the upstream printing apparatus 10 and second image data to be printed by the downstream printing apparatus 30 (step S203). Here, in two-pass printing, duplex printing is performed by printing both sides with the upstream printing apparatus 10 and then printing both sides with the downstream printing apparatus 30, so the job dividing unit 42 performs duplex printing with the upstream printing apparatus 10. The front and back image data for printing is assigned as first image data, and the front and back image data is assigned as second image data. When the upstream printing apparatus 10 performs single-sided printing on the front surface and the downstream printing apparatus 30 performs double-sided printing on the front and back surfaces, the image data on the front surface is assigned to the first image data, and the surface and Assign the back side image data. Further, when duplex printing is performed by the upstream printing apparatus 10 and single-sided printing of the front surface is performed by the downstream printing apparatus 30, the front and back image data is allocated to the first image data, and the front image data is allocated to the second image data. Is assigned.

  Next, the communication unit 47 transmits the first image data to the upstream printing apparatus 10 and transmits the second image data to the downstream printing apparatus 30 (step S205).

  When the upstream printing apparatus 10 receives the first image data (step S207), the acquisition unit 163 acquires the resolution and density from the received first image data, and also sets the paper size and single-sided duplex setting from the overall control apparatus 40. Is acquired (step S209).

  Then, the calculation unit 164 calculates the first transport speed V1 transported by the transport belt 133 of the upstream printing apparatus 10 based on the resolution and density of the first image data acquired by the acquisition unit 163 (step S211). ).

  On the other hand, when the downstream printing apparatus 30 receives the second image data (step S213), the acquisition unit 363 acquires the resolution and density from the received second image data, and the paper size and one side from the overall control apparatus 40. The duplex setting is acquired (step S215).

  Then, the calculation unit 364 calculates the second conveyance speed V2 that is conveyed by the conveyance belt 333 of the downstream printing apparatus 30 based on the resolution and density of the second image data acquired by the acquisition unit 363 (step S217). ).

  The communication unit 361 transmits the calculated second transport speed V2 to the upstream printing apparatus 10 (step S219).

  When the upstream printing apparatus 10 receives the second transport speed V2 (step S221), the calculation unit 164 calculates the reference sheet interval between the upstream printing apparatus 10 and the downstream printing apparatus 30 (step S223). This reference sheet interval is determined based on the sheet size and single-sided / double-sided settings included in the print setting information. For example, when both the upstream printing apparatus 10 and the downstream printing apparatus 30 perform double-sided printing, the same reference sheet interval is used. On the other hand, when the upstream printing apparatus 10 performs single-sided printing on the front surface and the downstream printing apparatus 30 performs double-sided printing on the front and back surfaces, the reference sheet interval of the upstream printing apparatus 10 is set to the downstream printing apparatus 30. It is set as twice the reference sheet interval. In addition, when performing double-sided printing on the front and back surfaces with the upstream printing device 10 and single-sided printing with the downstream printing device 30, the reference sheet interval of the downstream printing device 30 is set to the reference of the upstream printing device 10. Set as twice the paper interval.

  Next, as shown in FIG. 7, the correction unit 165 of the upstream printing apparatus 10 sets the first printing cycle and the second printing cycle based on the paper size and the reference paper interval (step S225), It is determined whether the second transport speed V2 received from the downstream printing apparatus 30 is less than the first transport speed V1 calculated by the calculation unit 164 (step S227).

  When the second transport speed V2 is equal to or higher than the first transport speed V1 (step S227; NO), the communication unit 161 notifies the downstream printing apparatus 30 of the start of printing (step S233).

  On the other hand, when the second transport speed V2 is less than the first transport speed V1 (step S227; YES), the correction unit 165 described the correction value CV1 for correcting the paper feed timing so that the paper P does not come into contact. Calculation is performed using (Formula 1) (step S229).

  If double-sided printing is performed by the upstream printing apparatus 10 and single-sided printing of the surface is performed by the downstream printing apparatus 30, double-sided printing by the upstream printing apparatus 10 requires more time, so continuous printing is performed with the shortest paper interval. It becomes possible to do. Therefore, in this case, correction by the correction unit 165 can be omitted.

  Then, the correction unit 165 adds the calculated correction value CV1 to the first print cycle set in step S225 to newly set the first print cycle, so that the registration roller 114 is placed on the circulation conveyance path CR1. The paper feed timing for transporting the paper P to the paper is corrected (step S231).

  When the upstream printing apparatus 10 notifies the downstream printing apparatus 30 of the start of printing (step S233), the upstream printing apparatus 10 feeds paper at the paper feed timing based on the first printing cycle based on the first image data and starts printing (step S233). S235). The printed paper P is conveyed to the downstream printing device 30 after being turned upside down by the intermediate device 20.

  When all the first image data is printed (step S237; YES), the upstream printing apparatus 10 ends the process.

  On the other hand, when the downstream printing apparatus 30 is notified of the start of printing by the upstream printing apparatus 10 (step S233), the downstream printing apparatus 30 enters a standby state until the paper P is conveyed from the intermediate apparatus 20 (step S239).

  When the paper P arrives from the intermediate device 20 (step S241; YES), the downstream printing apparatus 30 feeds paper at the paper feed timing based on the second print cycle based on the second image data and starts printing (step). S243). When all the second image data is printed (step S245; YES), the downstream printing apparatus 30 ends the process.

  As described above, according to the double-sided printing system 1 according to the second embodiment of the present invention, the correction unit 165 has the length in the transport direction of the transported paper, the first transport speed V1, and the second transport speed V2. And the correction value CV1 based on the single-sided duplex setting information, and based on the calculated correction value CV1, the upstream printing apparatus 10 determined by the first printing cycle corrects the paper feed timing at which the paper starts to be conveyed on the conveyance path. To do.

  Therefore, when duplex printing is performed by the upstream printing apparatus 10 and the downstream printing apparatus 30 respectively, or when simplex printing is performed by either the upstream printing apparatus 10 or the downstream printing apparatus 30, and duplex printing is performed by the other. Even in such a case, the paper P printed by the upstream printing apparatus 10 and turned upside down by the intermediate apparatus 20 and conveyed to the downstream printing apparatus 30 does not contact the paper P printed by the downstream printing apparatus 30. As described above, the upstream printing apparatus 10 sets an appropriate first printing cycle, and performs printing in this first printing cycle. Therefore, it is possible to prevent a paper jam due to the contact of the paper P.

(Appendix)
The present application discloses the following inventions.

(Appendix 1)
An upstream printing apparatus that executes a printing process on one side of a sheet conveyed on a conveyance path in a first printing cycle based on first image data included in the print job, and a printing process performed by the upstream printing apparatus A downstream printing apparatus that executes a printing process on the other surface of the sheet conveyed on the conveyance path in a second printing cycle based on the second image data included in the print job. A duplex printing system that performs duplex printing using
Acquisition means for acquiring the resolution and density of each of the first image data and the second image data included in the print job;
Based on the resolution and density acquired by the acquisition means, a first transport speed for transporting on the transport path of the upstream printing apparatus and a second transport speed for transporting on the transport path of the downstream printing apparatus are calculated. A calculation means;
When the second transport speed is less than the first transport speed, the upstream sheet is transported so that the sheet transported from the upstream printing apparatus to the downstream printing apparatus does not contact the sheet transported in the second printing cycle. Correct means for correcting the paper feed timing at which the side printing apparatus starts transporting paper on the transport path;
A double-sided printing system comprising:

(Appendix 2)
The correction means includes
A correction value is calculated based on the length of the transported paper in the transport direction, the first transport speed, and the second transport speed, and the upstream printing apparatus performs the transport based on the calculated correction value. The double-sided printing system according to (Appendix 1), wherein a paper feeding timing at which paper conveyance starts on the road is corrected.

(Appendix 3)
The upstream side printing apparatus and the downstream side printing apparatus have a circulation path for printing one side of a sheet conveyed on the conveyance path and then reversing the front and back to print the other side,
The print job includes single-sided duplex setting information for instructing single-sided printing or duplex printing,
The correction means includes
A correction value is calculated based on the length of the transported paper in the transport direction, the first transport speed, the second transport speed, and the single-sided duplex setting information, and the correction value is calculated based on the calculated correction value. The double-sided printing system according to (Appendix 1), wherein the upstream printing apparatus corrects a paper feed timing at which the paper starts to be transported on the transport path.

DESCRIPTION OF SYMBOLS 1 Duplex printing system 10 Upstream printing apparatus 20 Intermediate apparatus 30 Downstream printing apparatus 40 Overall control apparatus 41 Job receiving part 42 Job division part 43 Acquisition part 44 Calculation part 45 Correction part 47 Communication part 100 Terminal apparatus 110 Side paper feeding part 120 , 320 Internal paper feeding unit 130, 330 Printing unit 140, 340 Paper discharge unit 150, 350 Inversion unit 160, 360 Device control unit 161, 361 Communication unit 163, 363 Acquisition unit 164, 364 Calculation unit 165 Correction unit 210 Carrying unit 260 Device control unit 310 Intermediate transfer unit

Claims (3)

An upstream printing apparatus that executes a printing process on one side of a sheet conveyed on a conveyance path in a first printing cycle based on first image data included in the print job, and a printing process performed by the upstream printing apparatus A downstream printing apparatus that executes a printing process on the other surface of the sheet conveyed on the conveyance path in a second printing cycle based on the second image data included in the print job. A duplex printing system that performs duplex printing using
Acquisition means for acquiring the resolution and density of each of the first image data and the second image data included in the print job;
Based on the resolution and density acquired by the acquisition means, a first transport speed for transporting on the transport path of the upstream printing apparatus and a second transport speed for transporting on the transport path of the downstream printing apparatus are calculated. A calculation means;
When the second transport speed is less than the first transport speed, the upstream sheet is transported so that the sheet transported from the upstream printing apparatus to the downstream printing apparatus does not contact the sheet transported in the second printing cycle. Correct means for correcting the paper feed timing at which the side printing apparatus starts transporting paper on the transport path;
A double-sided printing system comprising: The correction means includes
A correction value is calculated based on the length of the transported paper in the transport direction, the first transport speed, and the second transport speed, and the upstream printing apparatus performs the transport based on the calculated correction value. The double-sided printing system according to claim 1, wherein a paper feed timing at which paper conveyance starts on the road is corrected. The upstream side printing apparatus and the downstream side printing apparatus have a circulation path for printing one side of a sheet conveyed on the conveyance path and then reversing the front and back to print the other side,
The print job includes single-sided duplex setting information for instructing single-sided printing or duplex printing,
The correction means includes
A correction value is calculated based on the length of the transported paper in the transport direction, the first transport speed, the second transport speed, and the single-sided duplex setting information, and the correction value is calculated based on the calculated correction value. The double-sided printing system according to claim 1, wherein an upstream printing apparatus corrects a paper feed timing at which paper conveyance starts on the conveyance path.

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