JP7127716B2 - Printing system, printing system control method - Google Patents

Description

The present invention relates to a printing system having a printing device such as an ink jet printer that prints on paper such as a medium to be transported, and a control method thereof .

2. Description of the Related Art Conventionally, an image forming apparatus that records (prints) an image on a conveyed paper (medium) is known as an example of a printing apparatus included in a printing system. Further, some image forming apparatuses have a switchback mechanism (reversing section) for reversing the sheet (for example, Japanese Unexamined Patent Application Publication No. 2002-100001).

That is, the switchback mechanism has rollers, and rotates the rollers forward and backward to shift the paper sent from the upstream transport path (first transport path/pre-reversal path) to the downstream transport path (second transport path). / post-reversal path) to be reversed.

In this image forming apparatus, two switchback mechanisms are provided, and one roller is used both as a roller for feeding paper to one of the switchback mechanisms and as a roller for feeding paper from the other switchback mechanism. That is, when this roller rotates forward, the paper is sent to one switchback mechanism and the paper is sent out from the other switchback mechanism. Then, when the roller reverses, the paper is fed from one switchback mechanism and fed to the other switchback mechanism.

Therefore, the roller feeds the paper from the switchback mechanism to the downstream transport path at the same speed as the paper is fed from the upstream transport path to the switchback mechanism.

JP-A-9-12198

By the way, when a liquid such as ink is adhered to the surface of paper and printing is performed, the paper may curl into a ball. This curling is thought to be caused by the difference in expansion coefficient between the portion on the front side where the adhering liquid permeates and the back side on which the ink does not permeate. As time elapses after the liquid adheres to the paper, the liquid permeates the back side or evaporates, and the curl is gradually reduced.

Also, the paper swollen by absorbing the liquid fixes its shape as the liquid evaporates and dries. That is, for example, if the paper is dried while the transport of the paper is interrupted, the paper is fixed in the shape of the transport path. Therefore, it is preferable to change the shape of the paper by transporting it until the adhering liquid dries.

Now, in the case of the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200011, the speed at which the paper is sent out from the switchback mechanism is determined by the speed at which the paper is sent to the switchback mechanism. Therefore, in order to lengthen the transport time, it is necessary to lengthen the transport path of the paper, which causes the problem of increasing the size of the apparatus.

This problem is not limited to image forming apparatuses that record on paper, but is generally common to printing apparatuses that print on media.
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a printing system having a printing apparatus capable of securing a necessary transport time while suppressing an increase in the size of the apparatus.

Means for solving the above problems and their effects will be described below.
A printing system for solving the above-described problems includes a printing unit that applies liquid to a medium for printing, an upstream transport path for transporting the medium printed by the printing unit, and An intermediate transport path for transporting the medium from the path is provided, the intermediate transport path including a switchback path for switching back the medium, a reverse path for reversing the medium transported from the switchback path, and the reverse path. an intermediate device including a post-reversal route for transporting the medium reversed by the intermediate device; a downstream transport route for transporting the medium from the intermediate transport route; A post-processing device including a post-processing unit that performs processing and a discharge unit that discharges a medium post-processed by the post-processing unit, wherein a second conveying speed that is a conveying speed of the medium in the post-reversal path is , the distance between the trailing edge of the preceding medium and the leading edge of the medium following the preceding medium is slower than the first conveying speed that is the conveying speed of the medium in the upstream conveying path, It is shorter when the preceding medium is transported at the second transport speed than when transported at the first transport speed.

According to this configuration, the medium before being reversed is transported at the first transport speed, and the medium after being reversed is transported at the second transport speed, which is slower than the first transport speed. Therefore, the time required for transporting the post-reversal path can be made longer than the time required for transporting the post-reversal path at the first transport speed. Therefore, it is possible to ensure the necessary transport time while suppressing the increase in size of the apparatus. In addition, by reducing the transport speed of the medium after reversing and shortening the distance between the media before reversing, it is possible to prevent the media from coming into contact with each other unintentionally.

The printing system further includes a transport control section for controlling transport of the medium, and the printing apparatus in the printing system includes a cassette for placing the medium and a feeding section for feeding the medium from the cassette. and the transport controller controls the preceding medium and the subsequent When the unit adhesion amount is larger than the threshold value, the interval between the preceding medium and the succeeding medium is set to the first distance. When the feeding unit is controlled to provide a second gap wider than the gap, and the gap between the preceding medium and the following medium is the first gap as the transport speed of the medium in the post-reversal path is controlled to be the second transport speed, and when the interval between the preceding medium and the succeeding medium is the second interval, the fourth transport speed is lower than the second transport speed. It is preferable to control the conveying speed so as to achieve the conveying speed.

According to this configuration, the larger the unit adhesion amount, the longer the required transport time. Furthermore, the slower the transport speed of the medium, the narrower the distance between the mediums. In this regard, according to this configuration, the interval between the media during feeding is changed according to the unit adhesion amount. Therefore, even if the unit adhesion amount is large, by increasing the distance between the media in advance, even if the media are transported at a sufficiently slow transport speed, it is possible to suppress the occurrence of stains due to overlapping of the media. can. Further, in the case of conveying a medium having a large unit adhesion amount and requiring a long conveying time, the medium is conveyed through the post-reversal path at a fourth conveying speed slower than the second conveying speed. Therefore, compared to the case where the medium is transported at the second transport speed, the time required for transporting the medium after reversal can be made longer.

In the above printing system, it is preferable that the transport control unit controls the transport speed of the medium so that the transport speed of the medium becomes a third transport speed faster than the second transport speed in the downstream transport path.

In a post-processing unit that processes media, for example, if the distance between a plurality of transported media is narrow, the next medium is transported before the processing of the previously transported medium is completed, resulting in erroneous processing. There is a risk that In this respect, according to this configuration, the medium is transported in the downstream transport path at the third transport speed that is faster than the second transport speed. Therefore, even if the space between the media becomes narrow in the process of being conveyed through the post-reversal path, the space between the media can be widened, so processing in the post-processing section can be performed appropriately.

In the printing system, the transport control unit may set the interval between the preceding medium and the succeeding medium to be larger after switching back each of the media than the interval before switching back each of the media. It is preferable to control the transport so that the distance between the preceding media is narrowed, and the distance when the preceding medium is transported at the third transport speed is controlled so that the distance is wider than the distance after the switchback. .

According to this configuration, it is possible to promote the drying of the media in the intermediate transport path, and to secure the space between the media for appropriately performing the post-processing in the post-processing section.

In the above-described printing system, the intermediate conveying route includes a plurality of pairs of the switchback route and the reversing route, and the plurality of reversing routes join the post-reversing route to form the post-reversing route. It is preferable that the transport speed of the medium is the second transport speed or the fourth transport speed.

In the above printing system, the upstream end of the preceding medium and the downstream end of the succeeding medium are conveyed in a state separated from each other in the upstream conveying path, and the upstream end of the preceding medium and the upstream end of the preceding medium are conveyed in the post-reversal path. After the preceding medium reaches the third transport speed in the downstream transport path, the upstream end and the downstream end are separated again. is preferred.

According to this configuration, since the medium can be separated from the downstream side transport path while the efficiency of transporting the medium in the post-reversal path is increased, the post-processing can be performed appropriately in the post-processing section.

1 is a schematic diagram of one embodiment of a printing system; FIG. Schematic diagram of an intermediate device. Block diagram of a control unit. FIG. 4 is a schematic diagram of an intermediate device that conveys the first medium; FIG. 4 is a schematic diagram of an intermediate device that conveys the first and second media; FIG. 4 is a schematic diagram of an intermediate device that conveys the first to third media; FIG. 4 is a schematic diagram of an intermediate device that conveys the first to fourth media;

An embodiment of a printing system will be described below with reference to the drawings.
As shown in FIG. 1, a printing system 11 includes a device main body 13, which is an example of a first device such as a printing device that prints on a medium 12 such as paper, and a second device that processes the printed medium 12. A post-processing device 14, which is an example, and an intermediate device 15, which is an example of a third device, positioned between the device main body 13 and the post-processing device 14 are provided.

The apparatus main body 13 is provided with an upstream transport path 17 , and the intermediate apparatus 15 is provided with an intermediate transport path 18 . Further, the post-processing device 14 is provided with a downstream transport path 19 . 1 from the apparatus main body 13 on the upstream side in the conveying direction Y to the post-processing apparatus 14 via the intermediate apparatus 15 by the upstream conveying path 17, the intermediate conveying path 18, and the downstream conveying path 19. A conveying route indicated by a dotted chain line is configured.

At least one (four in FIG. 1) cassettes 21 capable of storing the media 12 in a stacked state are detachably provided in the apparatus main body 13 . The device main body 13 is transported by a feeding unit 22 that feeds the medium 12 contained in the cassette 21, an upstream transport unit 23 that transports the fed medium 12, and an upstream transport unit 23. and a printing unit 24 for printing on the medium 12 .

The feeding unit 22 includes a pickup roller 26 that feeds out the uppermost medium 12 among the media 12 arranged in the cassette 21 in a stacked state, and a separation roller pair that separates the medium 12 fed out by the pickup roller 26 one by one. 27. Further, the feeding section 22 includes a feeding motor 28 for rotating the pickup roller 26 .

The upstream transport unit 23 rotates with the driving of the upstream transport motor 29, thereby forming at least one (two in FIG. 1) upstream transport rollers that transport the medium 12 along the upstream transport path 17. It has pair 30. Furthermore, a driving pulley 32 and a driven pulley 33 around which an endless conveying belt 31 is stretched are provided along the upstream conveying path 17 . The medium 12 is conveyed as the conveying belt 31 rotates while being electrostatically attracted to the supporting surface (outer peripheral surface) of the conveying belt 31 .

The printing unit 24 is provided at a position facing the transport belt 31 across the upstream transport path 17 . The printing unit 24 ejects liquid such as ink onto the medium 12 transported while being supported by the transport belt 31 , thereby causing the liquid to adhere to the medium 12 transported by the upstream transport unit 23 for printing. Note that the printing unit 24 of the present embodiment is a so-called line head capable of simultaneously ejecting ink across a width direction that intersects (for example, is perpendicular to) the transport direction Y of the medium 12 .

The post-processing device 14 also includes a downstream transport section 35 that transports the medium 12 along the downstream transport path 19 , a post-processing section 36 that processes the medium 12 transported along the downstream transport path 19 , a processing and an ejection portion 37 for ejecting the medium 12 that has been ejected.

The downstream transport unit 35 rotates with the driving of the downstream transport motor 38, thereby forming at least one (one in FIG. 1) downstream transport roller that transports the medium 12 along the downstream transport path 19. It has pair 39. Then, the post-processing unit 36 performs, for example, stapler processing for binding the plurality of media 12 with staples.

Next, the intermediate device 15 will be described.
As shown in FIG. 1, the intermediate device 15 includes at least one reversing section (two first reversing sections 41 and a second reversing section 42 in this embodiment) for reversing the conveyed medium 12 . That is, the first reversing section 41 and the second reversing section 42 are positioned downstream in the transport direction Y from the printing section 24 in the transport path, and reverse the printed medium 12 .

The intermediate conveying route 18 includes an introducing route 43 whose upstream end is connected to the upstream conveying route 17, and a first branching route 44 and a second branching route 45 branched at a branch point A, which is the downstream end of the introducing route 43. and That is, the branch point A is connected to the downstream end of the introduction path 43, the upstream end of the first branched path 44, and the upstream end of the second branched path 45, respectively. While the introduction path 43 is formed in a substantially straight line, the first branch path 44 and the second branch path 45 are formed in a meandering curve. The lengths of the first branched route 44 and the second branched route 45 in the transport direction Y are substantially the same.

Further, the intermediate conveying route 18 is connected to a first reversing route 46 connected to a first connection point B, which is the downstream end of the first branch route 44, and a second connection point C, which is the downstream end of the second branch route 45. and a second inverting path 47 connected thereto. The lengths of the first reversing path 46 and the second reversing path 47 in the transport direction Y are substantially the same.

Further, the first connection point B is connected to the first switchback path 48 of the first inversion section 41, and the second connection point C is connected to the second switchback path of the second inversion section 42. 49 are connected. That is, the first connection point B is connected to the downstream end of the first branch path 44 , the upstream end of the first reverse path 46 , and one end of the first switchback path 48 . Also, the second connection point C is connected to the downstream end of the second branch path 45, the upstream end of the second reverse path 47, and one end of the second switchback path. The path lengths of the first switchback path 48 and the second switchback path 49 are configured to be longer than the medium length of the medium 12 printable in the apparatus main body 13 in the transport direction Y.

Further, the intermediate conveying route 18 has a lead-out route 50 connected to a junction D where the first reversing route 46 and the second reversing route 47 join. That is, the confluence D is connected to the downstream end of the first reverse path 46 , the downstream end of the second reverse path 47 , and the upstream end of the derivation path 50 . This lead-out path 50 extends downward in a meandering manner between the first switchback path 48 and the second switchback path 49 toward the post-processing device 14 , and then extends downward along the first switchback path 48 . It detours around the end side and extends upward. A downstream end of the outlet path 50 is connected to the downstream transport path 19 of the post-processing device 14 .

In this embodiment, the introduction route 43, the first branch route 44, and the second branch route 45 constitute the pre-reversal route 18a, and the first reverse route 46, the second reverse route 47, and the derivation route 50 constitute the post-reversal route. 18b is configured. The pre-reversal path 18 a functions as an example of a first transport path that is positioned upstream in the transport direction Y relative to the first reversing section 41 or the second reversing section 42 . Further, the post-reversal path 18b functions as an example of a second transport path that is positioned downstream in the transport direction Y from the first reversing section 41 or the second reversing section 42 in the transport direction Y. As shown in FIG. That is, the intermediate conveying path 18 includes a pre-reversing path 18a positioned upstream in the conveying direction Y from the first reversing section 41 and the second reversing section 42, and a post-reversing path 18b positioned downstream in the conveying direction Y. have. The downstream transport path 19 functions as an example of a third transport path positioned downstream in the transport direction Y from the post-reversal path 18b.

As shown in FIG. 2 , the intermediate device 15 includes an intermediate transport section 52 that transports the medium 12 along the intermediate transport path 18 . That is, the first reversing section 41 and the second reversing section 42 reverse the medium 12 conveyed by the intermediate conveying section 52 .

The intermediate transport section 52 includes a first transport roller pair 54 driven by a first transport motor 53 and a second transport roller pair 56 driven by a second transport motor 55 . A plurality of first transport roller pairs 54 (three pairs in FIG. 2) are provided in the pre-reversal path 18a, and a plurality of second transport roller pairs 56 (14 pairs in FIG. 2) are provided in the post-reversal path 18b. is provided.

In the printing system 11, the upstream transport unit 23, the downstream transport unit 35, and the intermediate transport unit 52 constitute a transport unit that transports the medium 12 along the transport path from the upstream side to the downstream side in the transport direction Y. It is That is, the conveying section rotates one of the rollers (the drive roller indicated by the double circles in FIGS. 1 and 2) while the medium 12 is sandwiched and supported by the pair of rollers from both the front and back sides. to transport the medium 12 along.

An introduction sensor 58 for detecting the medium 12 is provided in the introduction path 43 , and a guide flap 59 is provided at a branch point A downstream of the introduction sensor 58 . The guide flap 59 is driven by a solenoid (see FIG. 3) 60 to switch between the first branched path 44 and the second branched path 45 to guide the medium 12 transported through the introduction path 43 . That is, the guide flap 59 is positioned between a first position P1 that guides the medium 12 to the first branch path 44 and a second position (see FIG. 5) P2 that guides the medium 12 to the second branch path 45. can be switched.

Further, at the downstream end of the first branched path 44 , there is a switchback path 48 to the first branched path 44 while allowing the movement of the medium 12 from the first branched path 44 to the first switchback path 48 . A first restricting flap 61 is provided to restrict movement of the medium 12 . Furthermore, at the downstream end of the second branch path 45, while allowing the movement of the medium 12 from the second branch path 45 to the second switchback path 49, A second restricting flap 62 is provided to restrict movement of the medium 12 . These first regulation flap 61 and second regulation flap 62 are urged by an urging force of an urging member (not shown) so as to block the downstream end of the first branch path 44 or the second branch path 45 .

The first reversing unit 41 includes a first reversing sensor 64 that detects the medium 12 sent to the first switchback path 48, and a plurality of (two pairs in FIG. 1) second sensors provided on both sides of the first reversing sensor 64. 1 reversing roller pair 65 is provided. The first reversing roller pair 65 is driven forward or reverse by a first reversing motor 66 based on a signal transmitted by the first reversing sensor 64 when the medium 12 is detected.

The second reversing unit 42 includes a second reversing sensor 67 that detects the medium 12 sent to the second switchback path 49, and a plurality of sensors (two pairs in FIG. 1) provided on both sides of the second reversing sensor 67. and a second reversing roller pair 68. The second reversing roller pair 68 is driven forward or reverse by a second reversing motor 69 based on a signal transmitted by the second reversing sensor 67 when the medium 12 is detected.

As shown in FIG. 3 , the printing system 11 includes a control section 71 that controls driving of each mechanism in the printing system 11 in an integrated manner. This control unit 71 controls the driving of various motors and solenoids 60 based on the detection results of the introduction sensor 58, the first reversing sensor 64, and the second reversing sensor 67, thereby controlling the upstream conveying unit 23 and the intermediate conveying unit 52. , causes the downstream transport section 35 to transport the medium 12 .

The control unit 71 also includes a calculation unit 72 that calculates a unit amount of liquid applied per unit area of the medium 12 by the printing unit 24 based on the print data, and a predetermined threshold value for the unit amount of adhesion. and a storage unit 73 for storing the . That is, when print data is input to the printing system 11, the calculation unit 72 calculates the unit adhesion amount based on this print data.

Note that the threshold is set according to the type of medium 12 or liquid, the length of the transport path, and the like. That is, when the printing unit 24 performs printing by applying liquid to the surface (printing surface) of the medium 12, curling that makes the surface convex may occur. This curling is considered to be caused by the difference in expansion rate between the front and back sides, because the front side, which has absorbed the liquid, swells, while the back side, which has not permeated with the liquid, does not swell. Therefore, curling is more likely to occur as the unit adhesion amount increases. The curling is reduced as the liquid adhering to the front surface permeates the rear surface side, or as the liquid evaporates and the swelling on the front surface side is reduced.

Therefore, for example, in the case of a medium that is easily permeable by a liquid, it takes less time to reduce the curl than a medium that is difficult to be permeated by a liquid. A smaller threshold is set for a medium into which a liquid is less likely to permeate, or for a liquid that is less likely to permeate or evaporate.

Next, the interval at which the medium 12 is fed by the feeding section 22 and the transport speed at which the medium 12 is transported by the upstream transport section 23, the intermediate transport section 52, and the downstream transport section 35 will be described.
When the unit adhesion amount calculated by the calculation unit 72 is less than the threshold value stored in the storage unit 73, the feeding unit 22 feeds the media 12 at the first interval so that the unit adhesion amount is less than the threshold value. If the number of media 12 is too large, the media 12 are fed at a second spacing that is wider than the first spacing.

The conveying speed here may be the maximum conveying speed in a section of a predetermined conveying route, or may be an average conveying speed in a section of a predetermined conveying route. Moreover, when the media 12 are conveyed continuously, the speed of each of the media 12 is shown. However, the leading media 12 may be slower than the trailing media 12 for very short periods of time. For example, there is a moment when the leading medium 12 is slower than the trailing medium 12 when crossing the switchback path. Therefore, when comparing the velocities of the preceding medium 12 and the following medium 12, it is necessary to be aware of whether each medium 12 is switched back before or after.
The term "predetermined section of the conveying route" as used herein means, for example, a section of the upstream conveying route 17 defined by an arbitrary starting point and an arbitrary end point in the upstream conveying route 17, and an intermediate conveying route 18. is a section defined by an arbitrary starting point and an arbitrary end point in the intermediate conveying route 18, and a section defined by an arbitrary starting point and an arbitrary end point in the downstream conveying route 19 in the downstream conveying route 19 It is an interval.
Furthermore, it may be a section defined by an arbitrary starting point in the upstream conveying route 17 and an arbitrary ending point in the intermediate conveying route 18, or an arbitrary starting point in the intermediate conveying route 18 and the downstream conveying route 19. It may be an interval defined by any end point in . Furthermore, in the intermediate transport route 18, any starting point upstream from the first switchback route 48 and the second switchback route 49, and any end point downstream from the first switchback route 48 and the second switchback route 49. It may be an interval defined by

Note that the first interval and the second interval are the intervals between the media 12 in the transport direction Y. As shown in FIG. That is, for example, by setting the time from feeding the first medium to feeding the second medium to a second interval time longer than the first interval time, the interval between the media 12 can be shortened. The second spacing can be wider than the first spacing.

Then, the upstream transport section 23 transports the fed medium 12 along the upstream transport path 17 at a pre-reversal speed (an example of a first transport speed). Further, the intermediate transport unit 52 transports the medium 12 on the pre-reversal path 18a at a pre-reversal speed, and transports the medium 12 on the post-reversal path 18b at a post-reversal speed lower than the pre-reversal speed. Furthermore, the downstream transport section 35 transports the medium 12 along the downstream transport path 19 at a processing speed (an example of a third transport speed) faster than the post-reversal speed.

Note that the intermediate conveying section 52 changes the post-reversal speed according to the unit adhesion amount calculated by the calculating section 72 . That is, when the unit adhesion amount is less than the threshold value stored in the storage unit 73, the intermediate conveying unit 52 conveys the medium 12 along the post-reversal path 18b at the first post-reversal speed (an example of the second conveying speed). do. Then, when the unit adhesion amount is larger than the threshold value stored in the storage unit 73, the intermediate conveying unit 52 moves the post-reversal path 18b to a second post-reversal speed (fourth conveying speed) slower than the first post-reversal speed. (an example of) to transport the medium 12 .

That is, regardless of the unit amount of adhesion, the medium 12 fed at intervals corresponding to the amount of adhesion is conveyed through the upstream transportation path 17 and the pre-reversal path 18a at the pre-reversal speed, and along the downstream transportation path 19. Conveyed at processing speed. In the post-reversal path 18b, the medium 12 fed at the first interval is transported at the first post-reversal speed, and the medium 12 fed at the second interval is transported at the second post-reversal speed.

The processing speed is the fastest among the pre-reversal speed, the first post-reversal speed, the second post-reversal speed, and the processing speed. The processing speed is substantially the same as the pre-reversal speed or faster than the pre-reversal speed. The first post-reversal speed is slower than the pre-reversal speed, and the second post-reversal speed is slower than the first post-reversal speed (processing feed rate≧pre-reversal speed>first post-reversal speed>second post-reversal speed speed). The transport speed of the medium 12 may satisfy the above-described inequality, and the medium 12 may be transported at a constant speed or may be transported while accelerating or decelerating in a predetermined transport route section. good.

Next, the operation when the printing system 11 performs printing will be described.
In the following description, the media 12 fed and conveyed by the feeding unit 22 are assumed to be the first medium 12a, the second medium 12b, and the third medium 12c in order from the first medium, and the fourth medium 12 is assumed to be the medium 12c. It will be described as the fourth medium 12d.

Now, when printing is executed, the control unit 71 drives the feed motor 28 and the second transport motor 55 depending on whether the calculated unit adhesion amount is greater than the threshold value stored in the storage unit 73. to control. Further, the control unit 71 drives the upstream transport motor 29, the first transport motor 53, the first reversing motor 66, the second reversing motor 69, and the downstream transport motor 38 for forward rotation.

That is, the medium 12 is fed by the feeding section 22 and transported by the transport section. Further, the printing unit 24 performs printing by ejecting liquid onto the medium 12 at the timing when the medium 12 passes between the printing unit 24 and the conveying belt 31 .

As shown in FIG. 4, the first medium 12a conveyed along the upstream conveying path 17 at the pre-reversal speed is delivered to the introduction path 43 at substantially the same speed. When the introduction sensor 58 detects the leading edge of the first medium 12a, the controller 71 drives the solenoid 60 to position the guide flap 59 at the first position P1. That is, the guide flap 59 guides the first medium 12 a to the first branch path 44 . The leading end of the first medium 12a transported to the first connection point B contacts the first regulation flap 61, thereby moving the first regulation flap 61 against the biasing force of the biasing member. . That is, the first regulation flap 61 moves so as to open the downstream end of the first branch path 44 . Therefore, the first medium 12a is sent to the first switchback path 48 at the pre-reversal speed by the first reversing roller pair 65 that rotates forward. Then, when the first medium 12a passes through the first regulation flap 61, the first regulation flap 61 moves from the position that opens the downstream end of the first branch path 44 to the position that closes it.

As shown in FIG. 5, when the first reversing sensor 64 detects the trailing edge of the first medium 12a, the control unit 71 switches the first reversing motor 66, which has been driven for forward rotation, to drive for reverse rotation. Then, the first reversing section 41 sends out the first medium 12a from the first switchback path 48 to the first connection point B side at the post-reversal speed. Also, at this time, the first regulation flap 61 guides the first medium 12 a to the first reversing path 46 . That is, the first reversing section 41 reverses (switches back) the direction of the first medium 12a by feeding the first medium 12a sent from the first branch path 44 to the first reversing path 46 .

Further, when the introduction sensor 58 detects the leading edge of the second medium 12b, the control section 71 drives the solenoid 60 to change the position of the guide flap 59. FIG. That is, the control section 71 moves the guide flap 59 positioned at the first position P1 to the second position P2. The guide flap 59 then guides the second medium 12 b to the second branch path 45 .

The tip of the second medium 12b transported to the second connection point C contacts the second regulation flap 62, thereby moving the second regulation flap 62 against the biasing force of the biasing member. . That is, the second regulation flap 62 moves so as to open the downstream end of the second branch path 45 . Therefore, the second medium 12b is sent to the second switchback path 49 at the pre-reversal speed by the second reversing roller pair 68 that rotates forward. Then, when the second medium 12b passes through the second regulation flap 62, the second regulation flap 62 moves from the position that opens the downstream end of the second branch path 45 to the position that closes it.

As shown in FIG. 6, the first medium 12a reversed by the first reversing section 41 is conveyed through the post-reversal path 18b at the post-reversal speed. Then, when the first medium 12a passes through the first connection point B, the control section 71 drives the first reversing motor 66 to rotate forward.
Further, when the second reversing sensor 67 detects the trailing edge of the second medium 12b, the control section 71 drives the second reversing motor 69 in the reverse direction. That is, the second reversing section 42 reverses the second medium 12b in the same manner as the first reversing section 41 and sends it to the second reversing path 47 at the post-reversal speed.

The post-reversal speed at which the first reversing unit 41 sends out the first medium 12a from the first switchback path 48 to the first connection point B side, and the second reversing unit 42 transports the second medium 12b to the second switchback path 49 It is preferable that the post-reversal speed sent from the second connection point C side is the same. According to this configuration, the distance between the trailing edge of the preceding medium and the leading edge of the succeeding medium can be made constant in the transportation after each medium is reversed.

Furthermore, when the introduction sensor 58 detects the leading edge of the third medium 12c, the controller 71 drives the solenoid 60 to change the position of the guide flap 59. FIG. That is, the control section 71 moves the guide flap 59 positioned at the second position P2 to the first position P1. That is, the guide flap 59 alternately guides the conveyed medium 12 to the first branch path 44 and the second branch path 45 .

As shown in FIG. 7, the second medium 12b reversed by the second reversing section 42 and delivered to the second reversing path 47 is conveyed through the derivation path 50 via the junction D. As shown in FIG. At this time, the intermediate conveying unit 52 conveys the first medium 12a and the second medium 12b at a post-reversal speed slower than the pre-reversal speed. Therefore, the interval in the transport direction Y between the first medium 12a and the second medium 12b is narrower than when transported through the pre-reversal path 18a at the pre-reversal speed.

Then, when the first reversing sensor 64 detects the trailing edge of the third medium 12 c , the control section 71 drives the first reversing motor 66 in reverse to feed the third medium 12 c to the first reversing path 46 . Further, when the introduction sensor 58 detects the leading edge of the fourth medium 12d, the controller 71 drives the solenoid 60 to change the position of the guide flap 59 to the second position P2.

Then, the intermediate device 15 sends out to the post-processing device 14 sequentially from the first medium 12a introduced first. That is, media 12 is fed to post-processing device 14 with the printed surface facing the direction of gravity. In addition, since the downstream transport unit 35 transports the medium 12 at a processing speed higher than the post-reversal speed, the distance between the media 12 increases. Then, the post-processing section 36 performs processing such as stapling on the media 12 conveyed on the downstream conveying path 19 and discharges them to the discharge section 37 .

Note that the interval between the trailing edge of the preceding medium 12 and the leading edge of the succeeding medium 12 in the apparatus main body 13, that is, the interval before switching back, is defined as the interval S1. Also, in the intermediate device 15, the interval between the trailing end of the preceding medium 12 and the leading end of the succeeding medium 12 after both the preceding medium 12 and the succeeding medium 12 are switched back, the so-called interval after switching back, is Let the interval be S2. The distance between the trailing edge of the preceding medium 12 and the leading edge of the succeeding medium 12 when the trailing edge of the preceding medium 12 passes through the pair of downstream conveying rollers 39 of the post-processing device 14 is defined as an interval S3.

At this time, the following inequality holds at each interval.
Formula 1: Interval S1 > Interval S3 > Interval S2
or,
Formula 2: Interval S3>Interval S1>Interval S2
The size relationship between the interval S1 and the interval S3 can be appropriately adopted based on the transport path of the apparatus. For example, when the space between the media 12 in the apparatus main body 13 must be sufficiently wide, it is preferable to adopt Equation 1. On the other hand, when the post-processing in the post-processing unit 36 of the post-processing device 14 cannot be sufficiently performed in the interval S1, Equation 2 may be adopted. Alternatively, the interval S1 and the interval S3 may be the same if there is no problem with various processes in the device.

In any case, the interval S2 is narrower than the interval S1 and the interval S3. As a result, the interval between the media 12 can be narrowed in the intermediate device 15, and the media 12 can be transported at a slower speed than before the switchback, so that the time for drying the media 12 in the intermediate device 15 can be secured. be able to.

Incidentally, in order to make the interval S3 wider than the interval S2, the conveying speed of the downstream conveying roller pair 39 is set faster than the conveying speed of the conveying roller pair (for example, the second conveying roller pair) of the intermediate device 15. do it. In this case, if the transport roller pair of the intermediate device 15 is provided with a friction clutch or the like, even if the leading edge of the medium 12 is nipped by the downstream transport roller pair 39 and transport is started, the intermediate device 15 Since generation of back tension due to the portion of the medium 12 nipped by the pair of transport rollers can be reduced, disturbance of transport is prevented.

The rotational speed of the downstream transport roller pair 39 is faster than the rotational speed of the transport roller pair of the intermediate device 15 . Therefore, the interval S3 varies depending on the size of the transported medium 12 in the transport direction. That is, when the medium 12 is conveyed so that the long side of the medium 12 is parallel to the conveying direction, the downstream conveying roller pair 39 accelerates the medium 12 when conveying the A3 size and when conveying the A4 size. Since the time is longer for the A3 size, the interval S3 is longer when the A3 size is conveyed than when the A4 size is conveyed.

The reason why the interval S3 needs to be different according to the size of the medium 12 is that the larger the size of the medium in the transport direction, the more the plurality of media 12 are stapled in the post-processing section 36. This is because it takes a long time to align the end portions of the plurality of media 12, which are the portions to be processed, when performing stapler processing or the like. That is, since the surface area of the medium 12 of the A3 size is larger than that of the A4 size, it takes a long time to align the edges, which are the portions to be processed, due to the friction between the plural sheets of the medium 12 .

It should be noted that there is another method for defining the intervals S1, S2, and S3. That is, the interval S1 is the time difference between the time when the trailing edge of the preceding medium 12 reaches the upstream transport roller pair 30 of the apparatus main body 13 and the time when the trailing edge of the following medium 12 reaches it. , the interval S1. Further, as the interval S2, after both the preceding medium 12 and the succeeding medium 12 switch back, the succeeding medium 12 reaches the confluence point D on the intermediate conveying path 18 from the time when the trailing edge of the preceding medium 12 reaches the junction D. The difference time to the time when the trailing edge of 12 arrives can be considered as the interval S2. In addition, as the interval S3, the difference time from the time when the trailing edge of the preceding medium 12 reaches the downstream side transport roller pair 39 of the post-processing device 14 to the time when the trailing edge of the following medium 12 reaches can be considered as the interval S3.

In addition, various positions are conceivable as a reference position for the interval between the preceding medium 12 and the succeeding medium 12 . That is, as the interval S1, from the time when the trailing edge of the preceding medium 12 reaches the introduction sensor 58 located near the branch point A on the intermediate conveying path 18 to the time when the trailing edge of the following medium 12 reaches You may consider the time of the difference to as interval S1. Also, as the interval S2, from the time when the trailing edge of the preceding medium 12 reaches the first reversing sensor 64 of the first switchback path 48 to the second reversing sensor 67 of the second switchback path 49, The interval S2 may be the differential time until the trailing edge of the following medium 12 arrives. That is, the first switchback path 48 and the second switchback path 49 separately switch back the preceding medium 12 and the succeeding medium 12 branched from the branch point A from the viewpoint of improving the transportation efficiency. It is a route to Therefore, as a design concept of the intermediate conveying route 18, the first switchback route 48 and the second switchback route 49 are designed to have the same conveying distance. By doing so, even if the preceding medium 12 and the succeeding medium 12 are branched and transported to different switchback paths, the interval between the preceding medium 12 and the succeeding medium 12 after switchback is properly managed. be able to. Therefore, if the conveying route is based on such a design concept, as the reference position of the interval S2, different positions such as the first reversing sensor 64 and the second reversing sensor 67 may be used. good.

In the above description, the interval is the time until the trailing edge of the preceding medium 12 and the trailing edge of the succeeding medium 12 pass at the reference positions of the respective intervals. Alternatively, the interval may be the interval of time until the leading edge of the preceding medium 12 and the trailing edge of the medium 12 at the reference position of each interval pass.

Incidentally, before and after switchback on the first switchback path 48 or the second switchback path 49, the start point and end point of the physical interval between the media 12 are different. That is, before switchback, it is the distance between the trailing edge of the preceding medium 12 and the leading edge of the succeeding medium 12 . On the other hand, after switchback, it is the interval between the trailing edge of the preceding medium 12 after switchback and the leading edge of the succeeding medium 12 after switchback. Furthermore, if the timing is after the preceding medium 12 switches back and before the succeeding medium 12 switches back, the interval between the mediums 12 is the trailing end of the preceding medium 12 after the switchback. It is the distance from the leading edge of the following medium 12 before switchback.

According to the above embodiment, the following effects can be obtained.
(1) The intermediate conveying unit 52 conveys the medium 12 before being reversed at a pre-reversing speed, and the medium 12 after being reversed by the first reversing unit 41 or the second reversing unit 42 is transported at a speed lower than the pre-reversing speed. Convey at the speed after reversing. Therefore, the time required for transporting the post-reversal path 18b can be made longer than the time required for transporting the post-reversal path 18b at the pre-reversal speed. Therefore, it is possible to ensure the necessary transport time while suppressing the increase in size of the apparatus.

(2) In the post-processing unit 36 that processes the media 12, for example, if the distance between a plurality of media 12 to be transported is narrow, the next medium 12 is transported before finishing the processing of the previously transported medium 12. There is a risk of incorrect processing. In this regard, the downstream transport section 35 transports the medium 12 in the downstream transport path 19 at a processing speed faster than the post-reversal speed. Therefore, even if the space between the media 12 narrows during the process of being conveyed through the post-reversal path 18b, the space between the media 12 can be widened.

(3) The greater the unit adhesion amount, the longer the required transport time. Furthermore, the slower the transport speed of the medium 12, the narrower the interval between the mediums 12 becomes. In this regard, the interval between the media 12 during feeding is changed according to the unit adhesion amount. Therefore, even when the unit adhesion amount is large, the medium 12 can be transported at a sufficiently slow transport speed while suppressing the occurrence of stains or the like due to the overlapping of the media 12 .

(4) When transporting the medium 12 with a large unit adhesion amount and a long required transport time, the downstream transport section 35 transports the medium 12 through the post-reversal path 18b at a second post-reversal speed slower than the first post-reversal speed. 12 is transported. Therefore, compared with the case where the medium 12 is conveyed at the first post-reversal speed, the time required for conveying the medium 12 through the post-reversal path 18b can be made longer.

(5) Since the printing system 11 includes the device main body 13, the post-processing device 14, and the intermediate device 15, the combination of devices can be easily changed. Therefore, for example, by exchanging the post-processing device 14, the processing performed on the medium 12 by the post-processing section 36 can be easily changed.

(6) The medium 12 is dried while being conveyed by the conveying section. Therefore, by conveying the post-reversal path 18b at a post-reversal speed slower than that of the pre-reversal path 18a to lengthen the transport time, for example, even if the medium 12 curls during printing, the curl is reduced. The medium 12 can be ejected. Therefore, for example, it is possible to reduce the occurrence of medium clogging and processing defects that occur when the curled medium 12 is processed by the post-processing section 36 .

(7) Overlapping of the media 12 can be reduced by changing the interval between the media 12 when the feeding unit 22 feeds the media 12 and the speed after reversal according to the unit adhesion amount. Therefore, it is possible to reduce the occurrence of medium clogging due to the media 12 coming into contact with each other.

Note that the above embodiment may be modified as follows.
- In the above embodiment, three or more reversing units may be provided.
- In the above embodiment, a separate motor for driving the second transport roller pair 56 located on the most downstream side in the transport direction Y may be provided. That is, the speed at which the medium 12 is fed from the post-reversal path 18b to the downstream transport path 19 may be different from the post-reversal speed. For example, the intermediate transport unit 52 may deliver the medium 12 from the post-reversal path 18b at a delivery speed (an example of a fifth transport speed) higher than the first post-reversal speed (first modified example). The delivery speed is faster than the first post-reversal speed and preferably equal to or slower than the processing speed (processing speed≧delivery speed≧pre-reversal speed>first post-reversal speed>second post-reversal speed ).

According to this first modification, the medium 12 is conveyed through the post-reversal path 18b at the first post-reversal speed, and is delivered from the post-reversal path 18b at a delivery speed higher than the first post-reversal speed. Therefore, for example, even if the media 12 overlap each other during the transport of the post-reversal path 18b, the media 12 can be separated from each other and sent out from the post-reversal path 18b. That is, the media 12 can be separated from each other and delivered to the downstream transport path 19 .

- In the above-described embodiment, the intermediate conveying unit 52 may convey the post-reversal path 18b in a state in which the media 12 are partly overlapped. It should be noted that the overlapped portion at this time is preferably a blank portion that is not printed. Then, when the medium 12 on the downstream side in the transport direction Y is pulled out by the downstream transport section 35 while the overlapped portion is nipped by the second transport roller pair 56, the second transport roller pair 56 is formed. The driving roller and the driven roller may be spaced apart.

- In the above embodiment, the transport speed of the medium 12 may be different between the upstream transport path 17 and the pre-reversal path 18a. For example, the upstream transport section 23 may transport the medium 12 along the upstream transport path 17 at a printing speed that is slower or faster than the pre-reversal speed.

- In the above embodiment, one motor may drive rollers on different paths. For example, the upstream transport roller pair 30 may be driven by the first transport motor 53 without the upstream transport motor 29 .

- In the above-described embodiment, the threshold for the unit adhesion amount stored in the storage unit 73 may be set or selected according to the environment in which the printing system 11 is installed. That is, the curl that occurs on the printed medium 12 is also influenced by the environment. Specifically, for example, in a low-humidity environment, the amount of moisture contained in the medium 12 before printing is small, so curling accompanying printing tends to increase. In addition, in a low temperature environment, the fluidity of the liquid is lowered and the liquid is difficult to evaporate, so it takes time to reduce the curl. Therefore, in an environment where it is difficult to reduce curl, the threshold may be decreased.

- In the above embodiment, a plurality of thresholds for the unit adhesion amount may be set, and the interval between the media 12 fed by the feeding unit 22 and the post-reversal speed may be changed stepwise.
In the above embodiment, regardless of the unit adhesion amount, the medium 12 may be transported through the post-reversal path 18b at a post-reversal speed (second transport speed) slower than the pre-reversal speed (first transport speed). That is, it is not necessary to set the second post-reversal speed.

In the above embodiment, the feeding unit 22 rotates the pickup roller 26 at the first rotation speed to feed the media 12 at the first interval, and rotates at the second rotation speed slower than the first rotation speed. The media 12 may be fed at a second spacing that is wider than the first spacing.

- In the above-described embodiment, the feeding unit 22 may feed the medium 12 at regular intervals regardless of the unit adhesion amount.
- In the above embodiment, the printing system 11 does not have to include the feeding unit 22 . For example, the printing system 11 may include a feed port, and the upstream transport section 23 may transport media 12 inserted one by one from the feed port. That is, the printing system 11 may print on the medium 12 fed by a feeding device provided separately from the printing system 11 . Further, the feeding unit 22 may feed the media 12 set on the feeding tray one by one.

In the above-described embodiment, the post-processing unit 36 performs punch processing for punching holes in the medium 12, shift processing for shifting and ejecting the medium 12 by set, cutting processing for cutting the medium 12, signature processing for folding the medium 12, and processing for folding the medium 12. 12 may be subjected to arbitrary processing such as bookbinding processing and collation processing.

- In the above embodiment, the printing system 11 may be configured without the post-processing device 14 .
Any liquid can be selected as long as it can be printed on the medium 12 by adhering to the medium 12 . The term "liquid" refers to any state in which a substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals. It shall include liquids such as (metal melt). Moreover, it includes not only a liquid as one state of a substance, but also a solution, dispersion, or mixture of particles of a functional material made of a solid substance such as a pigment or metal particles in a solvent. Ink is a representative example of the liquid. The ink includes general water-based ink, oil-based ink, and various liquid compositions such as gel ink and hot-melt ink.

- The medium 12 may be paper, resin, metal, cloth, ceramic, rubber, natural materials (wood, stone, etc.), or composites thereof. Also, the thickness of the medium may be plate, sheet, film, foil, or the like. Furthermore, the shape of the medium may be any shape such as rectangular or circular. That is, for example, composite films of paper and resin (resin-impregnated paper, resin-coated paper, etc.), composite films of resin and metal (laminate film), woven fabrics, non-woven fabrics, discs, circuit boards, and the like may be used. In the case of a medium that swells when liquid adheres to it, such as paper, curling can be reduced while the medium is being conveyed through the intermediate conveying path 18 . Also, in the case of a non-swelling medium, it does not curl, but can be dried while being conveyed through the intermediate conveying path 18 . Therefore, the medium 12 transported through the intermediate transport path 18 can be appropriately processed by the post-processing section 36 .

The printing system 11 is a device that prints images such as characters, pictures, and photographs by applying liquid such as ink to a medium, and may be a serial printer, a lateral printer, a line printer, a page printer, or the like. Alternatively, an offset printing device, a textile printing device, or the like may be used. Moreover, the printing apparatus may have at least a printing function for printing on a medium, and may be a multifunction machine having functions other than the printing function.

A... branch point, B... first connection point, C... second connection point, D... confluence point, P1... first position, P2... second position, Y... conveying direction, 11... printing system, 12... medium, 12a...first medium 12b...second medium 12c...third medium 12d...fourth medium 13...apparatus body (an example of a first apparatus) 14...post-processing apparatus (an example of a second apparatus) 15 Intermediate apparatus (an example of a third apparatus), 17 Upstream transport path, 18 Intermediate transport path, 18a Pre-reversal path (an example of a first transport path), 18b Post-reversal path (an example of a second transport path) ), 19... downstream transport path (an example of a third transport path), 21... cassette, 22... feeding section, 23... upstream transport section (an example of a transport section), 24... printing section, 26... pick-up roller, 27... Separation roller pair 28... Feed motor 29... Upstream transport motor 30... Upstream transport roller pair 31... Transport belt 32... Drive pulley 33... Driven pulley 35... Downstream transport unit (transport part), 36... Post-processing part, 37... Discharge part, 38... Downstream transport motor, 39... Downstream transport roller pair, 41... First reversing part, 42... Second reversing part, 43... Introduction path, 44 First branch route, 45 Second branch route, 46 First reverse route, 47 Second reverse route, 48 First switchback route, 49 Second switchback route, 50 Derivation route (reversal rear path), 52... Intermediate conveying section (an example of conveying section), 53... First conveying motor, 54... First conveying roller pair, 55... Second conveying motor, 56... Second conveying roller pair, 58... Introduction sensor , 59... Guide flap, 60... Solenoid, 61... First regulation flap, 62... Second regulation flap, 64... First reversing sensor, 65... First reversing roller pair, 66... First reversing motor, 67... Second Reversing sensor 68... Second reversing roller pair 69... Second reversing motor 71... Control unit (conveyance control unit) 72... Calculation unit 73... Storage unit.

Claims (9)

A printing device that includes a printing unit that applies liquid to a medium for printing, and an upstream transport path through which the medium printed by the printing unit is transported;
an intermediate device having an intermediate transport path through which the medium is transported from the upstream transport path;
A downstream transport path along which the medium is transported from the intermediate transport path, a post-processing section that performs post-processing on the medium transported from the downstream transport path, and a medium that has been post-processed by the post-processing section is discharged. and a post-processing device having a discharge unit for
The intermediate conveying route is
an introduction path through which the medium is introduced from the upstream transport path;
a switchback path including a first switchback path and a second switchback path for switching back the medium;
a guide path including a first guide path that transports the medium transported by the introduction path to the first switchback path, and a second guide path that transports the medium to the second switchback path;
a reversing path including a first reversing path for reversing and conveying the medium conveyed from the first switchback path, and a second reversing path for reversing and conveying the medium conveyed from the second switchback path;
a post-reversal path where the first reversing path and the second reversing path merge and convey the medium reversed in the reversing path;
A second transport speed, which is the transport speed of the medium in the post-reversal path, is slower than a first transport speed, which is the transport speed of the medium in the upstream transport path,
The distance between the trailing edge of the preceding medium and the leading edge of the medium following the preceding medium is greater than when the preceding medium is being conveyed at the first conveying speed. A printing system that is shorter when transporting at speed. 2. The printing system according to claim 1, further comprising a transport control section that controls transport of said medium. The transport control unit
When the unit deposition amount, which is the amount of liquid deposited per unit area of the medium by the printing unit, is smaller than a preset threshold value, the transportation speed of the medium in the post-reversal path is set to the second transportation Control the conveying speed so that the speed is
3. The printing system according to claim 2, wherein the transport speed is controlled to be a fourth transport speed lower than the second transport speed when the unit adhesion amount is greater than the threshold value. The transport control unit
4. The printing system according to claim 2, wherein the medium transport speed is controlled to be a third transport speed equal to or higher than the first transport speed in the downstream transport path. The transport control unit sets the interval between the preceding medium and the succeeding medium so that the interval after switching back each of the media is narrower than the interval before switching back each of the media. 5. The printing according to claim 4, wherein the transport is controlled so that the interval when the preceding medium is transported at the third transport speed is wider than the interval after the switchback. system. In the upstream transport path, transported with the upstream end of the preceding medium and the downstream end of the succeeding medium separated from each other;
In the post-reversal path, conveyed in a state where the upstream end of the preceding medium and the downstream end of the succeeding medium overlap,
6. The printing system according to claim 4 , wherein in the downstream transport path, the upstream end and the downstream end are separated again after the preceding medium reaches the third transport speed. The transport control unit
When the unit deposition amount, which is the amount of liquid deposited per unit area of the medium by the printing unit, is less than a preset threshold value, the second transportation speed is set as the transportation speed of the medium in the reversing path. Control the conveying speed so that
2. The method of claim 1, wherein when the unit adhesion amount is greater than the threshold value, the transport speed of the medium in the reversing path is controlled to be a fourth transport speed lower than the second transport speed. The printing system according to any one of claims 2 to 6 . The printing system according to any one of claims 1 to 7, wherein a transport speed of the medium in the guide path is a first transport speed. A control method for a printing system, comprising:
The printing system includes:
A printing apparatus having a printing unit that applies liquid to a medium for printing, and an upstream transport path through which the medium printed by the printing unit is transported;
an intermediate device having an intermediate transport path through which the medium is transported from the upstream transport path;
A downstream transport path along which the medium is transported from the intermediate transport path, a post-processing section that performs post-processing on the medium transported from the downstream transport path, and a medium that has been post-processed by the post-processing section is discharged. and a post-processing device having a discharge unit for
The intermediate conveying route is
an introduction path through which the medium is introduced from the upstream transport path;
a switchback path including a first switchback path and a second switchback path for switching back the medium;
a guide path including a first guide path that transports the medium transported by the introduction path to the first switchback path, and a second guide path that transports the medium to the second switchback path;
a reversing path including a first reversing path for reversing and transporting the medium transported from the first switchback path, and a second reversing path for reversing and transporting the medium transported from the second switchback path;
a post-reversal path where the first reversing path and the second reversing path merge and convey the medium reversed in the reversing path;
The control method is
making a second transport speed, which is the transport speed of the medium in the post-reversal path, slower than a first transport speed, which is the transport speed of the medium in the upstream transport path;
The distance between the trailing edge of the preceding medium in the post-reversal path and the leading edge of the medium following the preceding medium is the distance between the trailing edge of the preceding medium and the leading edge of the trailing medium in the upstream transport path be shorter than
A control method characterized by:

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