Abstract:
The present invention relates to a print system, such as an ink jet printer, which performs printing on a medium, such as a sheet that is transported.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a print system, such as an ink jet printer, which performs printing on a medium, such as a sheet that is transported. 
         [0003]    2. Related Art 
         [0004]    In the related art, as an example of a print apparatus, an image forming apparatus that records (prints) an image on a sheet (medium) that is transported is known. In addition, there is an image forming apparatus including a switchback mechanism (inversion unit) that inverts the sheet in the image forming apparatus (for example, JP-A-9-12198). 
         [0005]    That is, the switchback mechanism includes a roller, and a sheet fed from an upstream side transport path (first transport path) is sent and inverted on a downstream side transport path (second transport path) by rotating and counter-rotating the roller. 
         [0006]    In the image forming apparatus, two switchback mechanisms are provided; one roller is used as a roller that feeds the sheet to one switchback mechanism and another roller is used as a roller that sends the sheet from the other switchback mechanism. That is, when the roller rotates, the sheet is fed to the one switchback mechanism and the sheet is sent from the other switchback mechanism. When the roller counter-rotates, the sheet is sent from the one switchback mechanism and the sheet is fed to the other switchback mechanism. 
         [0007]    Therefore, the roller sends the sheet from the switchback mechanism to the downstream side transport path at the same speed as a speed for feeding the sheet from the upstream side transport path to the switchback mechanism. 
         [0008]    However, for example, when printing is performed by adhering liquid such as ink to a surface of a sheet, there is a case where curling of the sheet such as curving of the sheet occurs. Curling is considered to occur due to a difference in the expansion rates between a swollen portion of a front surface permeated by the adhered liquid and a rear surface not permeated by the liquid such as the ink. The curling due to the liquid permeating a rear surface or the liquid evaporating gradually decreases over time following the adhering of the liquid to the sheet. 
         [0009]    In addition, the shape of the sheet caused to swell by absorbing the liquid is fixed in accordance with the evaporation and drying of the liquid. That is, for example, when the sheet dries while transport of the sheet is stopped, the sheet is fixed in the shape of a transport path. Therefore, it is preferable that the shape be changed by transporting the sheet until the adhered liquid dries. 
         [0010]    In the case of the image forming apparatus of JP-A-9-12198, the speed for sending the sheet from the switchback mechanism is determined in accordance with the speed for feeding the sheet to the switchback mechanism. Therefore, there is a problem that the transport path of the sheet is increased to increase the transport time such that the size of the apparatus increases. 
         [0011]    The problem is not limited to the image forming apparatus that performs recording on a sheet, but is common to print apparatuses that print on a medium. 
       SUMMARY 
       [0012]    An advantage of some aspects of the invention is to provide a print apparatus capable of ensuring a required transport time while suppressing an increase in the size of the apparatus. 
         [0013]    Hereinafter, units for solving the problem and effects thereof will be described. 
         [0014]    According to an aspect of the invention, there is provided a print system including: a print apparatus including a printing unit that prints by adhering liquid to a medium, and an upstream side transport path that transports the medium printed on by the printing unit; an intermediate device including an intermediate transport path along which the medium is transported from the upstream side transport path, the intermediate transport path having a switchback path that switches back the medium, an inversion path that inverts the medium transported from the switchback path, and a post-inversion path that transports the medium inverted by the inversion path; and a post-processing device including a downstream side transport path along which the medium is transported from the intermediate transport path, a post-processing unit that performs post-processing on the medium transported from the downstream side transport path, and a discharge unit that discharges the medium on which the post-processing is performed by the post-processing unit, in which a second transport speed that is a transport speed of the medium on the post-inversion path is slower than a first transport speed that is the transport speed of the medium on the upstream side transport path, and in which a distance between a trailing end of a preceding medium and a leading end of a subsequent medium following the preceding medium during a period required for transporting the preceding medium at the second transport speed is less than that during a period required for transporting the preceding medium at the first transport speed. 
         [0015]    According to the configuration, before inversion is performed, a medium is transported at a first transport speed, and after inversion is performed, the medium is transported at a second transport speed slower than the first transport speed. Therefore, a time required for transporting along the second transport path can be longer than a time required in a case where transporting is performed at a first transport speed along the second transport path. Accordingly, it is possible to ensure a required transport time while suppressing an increase in the size of an apparatus. In addition, by decreasing intervals between media before inversion is performed according to a reduction in a transport speed of the medium after the inversion is performed, it is possible to suppress unintentional contact between media. 
         [0016]    The print system may further include a transport control unit that controls transporting of the medium. In the print system, it is preferable that the print apparatus include a sheet cassette in which the medium is placed and a feeding unit that feeds the medium from the sheet cassette, with the transport control unit controlling the feeding unit to cause a first interval as an interval between the preceding medium and the subsequent medium in a case where the unit adhesion amount, which is an amount of liquid which is caused by the printing unit to adhere to the medium per unit area of the medium, is less than a threshold value set in advance, controlling the feeding unit to cause a second interval larger than the first interval as the interval between the preceding medium and the subsequent medium in a case where the unit adhesion amount is greater than the threshold value, controlling the transport speed to be the second transport speed in a case where the interval between the preceding medium and the subsequent medium is the first interval, and controlling the transport speed to be a fourth transport speed slower than the second transport speed in a case where the interval between the preceding medium and the subsequent medium is the second interval, as the transport speed of the medium on the post-inversion path. 
         [0017]    According to the configuration, as the unit adhesion amount increases, the required transport time increases. Furthermore, as the transport speed of the medium decreases, intervals between media decrease. According to the configuration, the interval between the media at the time of feeding is changed in accordance with the unit adhesion amount. Therefore, even in a case where the unit adhesion amount is high, by increasing the intervals between media in advance, it is possible to suppress the occurrence of contamination or the like due to overlapping of media even though a medium is transported at a sufficiently slow transport speed. In addition, in a case where a medium having a high unit adhesion amount and a large required transport time is transported, the medium is transported at a fourth transport speed slower than a second transport speed along the post-inversion path. Therefore, it is possible to further increase a time required for transporting the medium along the post-inversion path, compared with a case where the medium is transported at the second transport speed. 
         [0018]    In the print system, it is preferable that the transport control unit control the transport speed of the medium to be a third transport speed faster than the second transport speed on the downstream side transport path. 
         [0019]    In the post-processing unit performing a process on the medium, for example, when intervals between a plurality of media to be transported decrease, there is a possibility that the next medium will be transported before completing processing of the medium that is transported in advance such that erroneous processing is performed. According to the configuration, the medium is transported at a third transport speed faster than the second transport speed on the downstream side transport path. Therefore, even in a case where the intervals between the media decrease while being transported along the post-inversion path, since it is possible to increase the intervals between the media, it is possible to appropriately perform a process in the post-processing unit. 
         [0020]    In the print system, it is preferable that the transport control unit control the transporting to cause an interval after which each of the media is switched back, the interval being smaller than an interval before which each of the media is switched back, as the interval between the preceding medium and the subsequent medium, and control the transporting to cause an interval larger than the interval after which the media is switched back when the preceding medium is transported at the third transport speed. 
         [0021]    According to the configuration, it is possible to promote drying of the medium on an intermediate transport path, and it is possible to ensure an interval between media for appropriately performing post-processing in the post-processing unit. 
         [0022]    In the print system, it is preferable that a plurality of pairs of the switchback path and the inversion path be provided on the intermediate transport path, that the plurality of the inversion paths be joined on the post-inversion path, and that the transport speed of the medium on the post-inversion path become the second transport speed or the fourth transport speed. 
         [0023]    In the print system, it is preferable that the transporting be performed in a state where an upstream end of the preceding medium and a downstream end of the subsequent medium are separated from each other on the upstream side transport path, that the transporting be performed in a state where the upstream end of the preceding medium and the downstream end of the subsequent medium overlap each other on the post-inversion path, and the upstream end and the downstream end be separated from each other again, after the preceding medium reaches the third transport speed, on the downstream side transport path. 
         [0024]    According to the configuration, since it is possible to separate the media from each other on a downstream side transport path while increasing transport efficiency of the medium on the post-inversion path, it is possible to appropriately perform the post-processing in the post-processing unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
           [0026]      FIG. 1  is a schematic diagram of an embodiment of a print apparatus. 
           [0027]      FIG. 2  is a schematic diagram of an intermediate device. 
           [0028]      FIG. 3  is a block diagram of a control unit. 
           [0029]      FIG. 4  is a schematic diagram of the intermediate device that transports the first medium. 
           [0030]      FIG. 5  is a schematic diagram of the intermediate device that transports the first and second media. 
           [0031]      FIG. 6  is a schematic diagram of the intermediate device that transports the first to third media. 
           [0032]      FIG. 7  is a schematic diagram of the intermediate device that transports the first to fourth media. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0033]    Hereinafter, an embodiment of a print apparatus will be described with reference to the drawings. 
         [0034]    As described in  FIG. 1 , a print apparatus  11  includes a device main body  13  that is an example of a first device such as a printer performing printing on a medium  12  such as a sheet, a post-processing device  14  that is an example of a second device performing a process on the printed medium  12 , and an intermediate device  15  that is an example of a third device positioned between the device main body  13  and the post-processing device  14 . 
         [0035]    An upstream side transport path  17  is provided in the device main body  13 , and an intermediate transport path  18  is provided in the intermediate device  15 . Furthermore, a downstream side transport path  19  is provided in the post-processing device  14 . A transport path denoted by a two-dot chain in  FIG. 1  is constituted by the upstream side transport path  17 , the intermediate transport path  18 , and the downstream side transport path  19  from the device main body  13  that is on an upstream side in the transport direction Y to the post-processing device  14  through the intermediate device  15 . 
         [0036]    At least one cassette  21  (four cassettes are shown in  FIG. 1 ) capable of accommodating the medium  12  in a stacked state is detachably provided in the device main body  13 . The device main body  13  includes a feeding unit  22  that feeds the medium  12  accommodated in the cassette  21 , an upstream side transport unit  23  that transports the fed medium  12 , and a printing unit  24  that prints on the medium  12  transported by the upstream side transport unit  23 . 
         [0037]    The feeding unit  22  includes a pickup roller  26  that sends the top medium  12  among the media  12  disposed in a stacked state on the cassette  21  and includes a separate roller pair  27  that separates the media  12  sent by the pickup roller  26  one at a time. Furthermore, the feeding unit  22  includes a feeding motor  28  for rotatably driving the pickup roller  26 . 
         [0038]    The upstream side transport unit  23  includes at least one upstream side transport roller pair  30  (two pairs are shown in  FIG. 1 ) that transport the medium  12  along the upstream side transport path  17  by rotating in accordance with driving of an upstream side transport motor  29 . Furthermore, a driving pulley  32  and a driven pulley  33  around which an endless transport belt  31  is wound are provided at a position along the upstream side transport path  17 . The medium  12  is transported in accordance with rotation of a transport belt  31  in a state of being electrostatically attracted to a supporting surface (outer peripheral surface) of the transport belt  31 . 
         [0039]    The printing unit  24  is provided at a position facing the transport belt  31  with the upstream side transport path  17  interposed therebetween. The printing unit  24  performs printing by adhering liquid to the medium  12  transported by the upstream side transport unit  23  by ejecting the liquid such as ink onto the medium  12  transported by being supported by the transport belt  31 . The printing unit  24  of the embodiment is a so-called line head capable of ejecting the ink at the same time in a width direction intersecting (for example, orthogonal to) the transport direction Y of the medium  12 . 
         [0040]    In addition, the post-processing device  14  includes a downstream side transport unit  35  that transports the medium  12  along the downstream side transport path  19 , a post-processing unit  36  that performs a process on the medium  12  transported along the downstream side transport path  19 , and a discharge unit  37  that discharges the processed medium  12 . 
         [0041]    The downstream side transport unit  35  includes at least one downstream side transport roller pair  39  (one pair is shown in  FIG. 1 ) that transports the medium  12  along the downstream side transport path  19  by rotating in accordance with driving of a downstream side transport motor  38 . For example, the post-processing unit  36  performs a process of stapling a plurality of media  12  with a staple (pin). 
         [0042]    Next, the intermediate device  15  will be described. 
         [0043]    As described in  FIG. 1 , the intermediate device  15  includes at least one inversion unit (two units of first inversion unit  41  and second inversion unit  42  in this embodiment) that inverts the transported medium  12 . That is, the first inversion unit  41  and the second inversion unit  42  are disposed on the downstream side of the printing unit  24  in the transport direction Y of the transport path and invert the printed medium  12 . 
         [0044]    In addition, the intermediate transport path  18  includes an introduction path  43  of which an upstream end is connected to the upstream side transport path  17 , and a first branch path  44  and a second branch path  45  which branch at a branch point A that is a downstream end of the introduction path  43 . That is, the downstream end of the introduction path  43 , an upstream end of the first branch path  44 , and an upstream end of the second branch path  45  are connected to the branch point A. The introduction path  43  is formed in an approximately straight line, but the first branch path  44  and the second branch path  45  are curved to meander. The path length of the first branch path  44  and the path length of the second branch path  45  in the transport direction Y are approximately the same as each other. 
         [0045]    Furthermore, the intermediate transport path  18  includes a first inversion path  46  connected to a first connection point B that is a downstream end of the first branch path  44 , and a second inversion path  47  connected to a second connection point C that is a downstream end of the second branch path  45 . The path length of the first inversion path  46  and the path length of the second inversion path  47  in the transport direction Y are approximately the same as each other. 
         [0046]    In addition, a first switchback path  48  included in the first inversion unit  41  is connected to the first connection point B, and a second switchback path  49  included in the second inversion unit  42  is connected to the second connection point C. That is, the downstream end of the first branch path  44 , an upstream end of the first inversion path  46 , and a one end of the first switchback path  48  are connected to the first connection point B. In addition, the downstream end of the second branch path  45 , an upstream end of the second inversion path  47 , and a one end of the second switchback path  49  are connected to the second connection point C. The path length of the first switchback path  48  and the path length of the second switchback path  49  are configured to be equal to or greater than a length of the medium  12  which can be printed on by the device main body  13  in the transport direction Y. 
         [0047]    Furthermore, the intermediate transport path  18  includes a derivation path  50  connected to a join point D at which the first inversion path  46  and the second inversion path  47  join. That is, a downstream end of the first inversion path  46 , a downstream end of the second inversion path  47 , and an upstream end of the derivation path  50  are connected to the join point D. 
         [0048]    After the derivation path  50  curves and extends downward to meander between the first switchback path  48  and the second switchback path  49  toward the post-processing device  14 , the derivation path  50  extends upward by bypassing the other end side of the first switchback path  48 . A downstream end of the derivation path  50  is connected to the downstream side transport path  19  of the post-processing device  14 . 
         [0049]    In the embodiment, a pre-inversion path  18   a  is constituted by the introduction path  43 , the first branch path  44 , and the second branch path  45 , and a post-inversion path  18   b  is constituted by the first inversion path  46 , the second inversion path  47 , and the derivation path  50 . The pre-inversion path  18   a  is an example of a first transport path positioned on the upstream side of the first inversion unit  41  or the second inversion unit  42  in the transport direction Y. Furthermore, the post-inversion path  18   b  is an example of a second transport path positioned on the downstream side of the first inversion unit  41  or the second inversion unit  42  in the transport direction Y. That is, the intermediate transport path  18  includes the pre-inversion path  18   a  positioned at the upstream side in the transport direction Y and the post-inversion path  18   b  positioned on the downstream side of the first inversion unit  41  and the second inversion unit  42  in the transport direction Y. The downstream side transport path  19  is an example of a third transport path positioned on the downstream side f the post-inversion path  18   b  in the transport direction Y. 
         [0050]    As described in  FIG. 2 , the intermediate device  15  includes an intermediate transport unit  52  that transports the medium  12  along the intermediate transport path  18 . That is, the first inversion unit  41  and the second inversion unit  42  invert the medium  12  transported by the intermediate transport unit  52 . 
         [0051]    The intermediate transport unit  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 the first transport roller pairs  54  (three pairs are shown in  FIG. 2 ) are provided on the pre-inversion path  18   a , and a plurality of the second transport roller pairs  56  ( 14  pairs are shown in  FIG. 2 ) are provided on the post-inversion path  18   b.    
         [0052]    In the print apparatus  11 , a transport unit that transports the medium  12  from the upstream side to the downstream side in the transport direction Y along the transport path is configured by the upstream side transport unit  23 , the downstream side transport unit  35 , and the intermediate transport unit  52 . That is, the transport unit transports the medium  12  along the transport path by rotatably driving one roller (drive roller shown by double circles in  FIG. 1  and  FIG. 2 ), in a state where each roller pair supports the medium  12  by interposing the medium  12  between leading and trailing sides thereof. 
         [0053]    In addition, an introduction sensor  58  that detects the medium  12  is provided on the introduction path  43 , and a guide flap  59  is provided at the branch point A of a downstream side of the introduction sensor  58 . The guide flap  59  is driven by a solenoid (see  FIG. 3 )  60 , and switches to guide the medium  12  transported along the introduction path  43  to one of the first branch path  44  and the second branch path  45 . That is, the guide flap  59  switches positions between a first position P 1  that guides the medium  12  to the first branch path  44 , and a second position P 2  (see  FIG. 5 ) that guides the medium  12  to the second branch path  45 . 
         [0054]    Furthermore, a first regulation flap  61  that permits movement of the medium  12  from the first branch path  44  to the first switchback path  48 , and regulates the movement of the medium  12  from the first switchback path  48  to the first branch path  44  in the downstream end of the first branch path  44 . Furthermore, a second regulation flap  62  that permits the movement of the medium  12  from the second branch path  45  to the second switchback path  49 , and regulates the movement of the medium  12  from the second switchback path  49  to the second branch path  45  in the downstream end of the second branch path  45 . The first regulation flap  61  and the second regulation flap  62  are biased to close the downstream end of the first branch path  44  or the second branch path  45  by a bias force of a bias member (not shown). 
         [0055]    The first inversion unit  41  includes a first inversion sensor  64  that detects the medium  12  fed to the first switchback path  48 , and a plurality of first inversion roller pairs  65  (two pairs are shown in  FIG. 1 ) that are provided at both sides of the first inversion sensor  64 . The first inversion roller pairs  65  are driven in a rotation state or a counter-rotation state by a first inversion motor  66  based on a signal that is transmitted at the time of detecting the medium  12  by the first inversion sensor  64 . 
         [0056]    In addition, the second inversion unit  42  includes a second inversion sensor  67  that detects the medium  12  fed to the second switchback path  49 , and a plurality of second inversion roller pairs  68  (two pairs are shown in  FIG. 1 ) that are provided at both sides of the second inversion sensor  67 . The second inversion roller pair  68  are driven in the rotation state or the counter-rotation state by a second inversion motor  69  based on a signal that is transmitted at the time of detecting the medium  12  by the second inversion sensor  67 . 
         [0057]    As described in  FIG. 3 , the print apparatus  11  includes a control unit  71  that collectively controls driving of each mechanism in the print apparatus  11 . The control unit  71  transports the medium  12  to the upstream side transport unit  23 , the intermediate transport unit  52 , and the downstream side transport unit  35  by controlling driving of various motors and a solenoid  60  based on a detection result of the introduction sensor  58 , the first inversion sensor  64 , and the second inversion sensor  67 . 
         [0058]    In addition, the control unit  71  includes a calculation unit  72  that calculates a unit adhesion amount that is an amount of liquid which adheres per unit area of the medium  12  by the printing unit  24  based on print data, and a storage unit  73  that stores a threshold value relating to a predetermined unit adhesion amount. That is, the calculation unit  72  calculates the unit adhesion amount based on the print data when the print data is input to the print apparatus  11 . 
         [0059]    The threshold value is set according to a type of the medium  12  and liquid, a length of the transport path, and the like. That is, when the printing unit  24  performs printing by adhering the liquid to a front surface (print surface) of the medium  12 , there is a case where curling in which the front surface has a convex shape occurs. Since a front surface side absorbing the liquid swells, but a rear side to which the liquid does not permeate does not swell, it is considered that the curling occurs due to a difference of expansion rates between the front and rear surfaces. Therefore, as the unit adhesion amount is high, the curling easily occurs. The liquid that adheres to the front surface permeates to the rear surface side or the liquid evaporates such that the curling is reduced in accordance with reduction of the swell on the front surface side. 
         [0060]    Accordingly, for example, in a case of the medium to which the liquid easily permeates, a time required for reducing the curling is shorter than that of the medium to which the liquid is difficult to permeate. The threshold value is set by a small value as the medium to which the liquid is difficult to permeate, and the liquid is difficult to permeate and evaporate. 
         [0061]    Next, a feeding interval of the medium  12  by the feeding unit  22 , and a transport speed for transporting the medium  12  by the upstream side transport unit  23 , the intermediate transport unit  52 , and the downstream side transport unit  35  will be described. In a case where 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  with a first interval, and in a case where the unit adhesion amount is greater than the threshold value, the feeding unit  22  feeds the media  12  with a second interval larger than the first interval. 
         [0062]    Here, the transport speed may be a maximum transport speed during a section of a predetermined transport path, and may be an average transport speed during a section of a predetermined transport path. In addition, in a case where the media  12  are continuously transported, a case of speed of all of the media  12  is represented. However, even though it is a short period, there is also a case where the preceding medium  12  is slower than the subsequent medium  12 . For example, when a switchback path is considered as a boundary, there is a moment where the preceding medium  12  is slower than the subsequent medium  12 . Therefore, in a case where speeds of the preceding medium  12  and the subsequent medium  12  are compared with each other, it is necessary to check whether before or after the medium  12  is switched back. Here, for example, the section of a predetermined transport path is a section defined by a certain start point and a certain end point within the upstream side transport path  17  on the upstream side transport path  17 , a section defined by a certain start point and a certain end point within the intermediate transport path  18  on the intermediate transport path  18 , and a section defined by a certain start point and a certain end point within the downstream side transport path  19  on the downstream side transport path  19 . Furthermore, a section defined by a certain start point within the upstream side transport path  17  and a certain end point within the intermediate transport path  18 , may be set, and a section defined by a certain start point within the intermediate transport path  18  and a certain end point on the downstream side transport path  19 , may be set. Furthermore, a section defined by a certain upstream start point from the switchback paths  48  and  49  and a certain downstream end point from the switchback paths  48  and  49 , may be set on the intermediate transport path  18 . 
         [0063]    The first interval and the second interval are intervals of the media  12  in the transport direction Y. That is, for example, a time from feeding of the first medium to feeding of the second medium is set as a second interval time larger than a first interval time such that it is possible to set intervals between the media  12  with the second interval larger than the first interval. 
         [0064]    The upstream side transport unit  23  transports the fed medium  12  at a pre-inversion speed (example of first transport speed) along the upstream side transport path  17 . Furthermore, the intermediate transport unit  52  transports the medium  12  at the pre-inversion speed along the pre-inversion path  18   a , and transports the medium  12  at the post-inversion speed slower than the pre-inversion speed along the post-inversion path  18   b . Furthermore, the downstream side transport unit  35  transports the medium  12  along the downstream side transport path  19  at a processing speed (example of third transport speed) faster than the post-inversion speed. 
         [0065]    The intermediate transport unit  52  changes the post-inversion speed according to the unit adhesion amount calculated by the calculation unit  72 . That is, in a case where the unit adhesion amount is less than the threshold value stored in the storage unit  73 , the intermediate transport unit  52  transports the medium  12  along the post-inversion path  18   b  at a first post-inversion speed (example of second transport speed). In a case where the unit adhesion amount is greater than the threshold value stored in the storage unit  73 , the intermediate transport unit  52  transports the medium  12  along the post-inversion path  18   b  at a second post-inversion speed (example of fourth transport speed) slower than the first post-inversion speed. 
         [0066]    That is, the medium  12  fed with an interval in accordance with the adhesion amount is transported at the pre-inversion speed along the upstream side transport path  17  and the pre-inversion path  18   a  regardless of the unit adhesion amount, and transported at the processing speed along the downstream side transport path  19 . In the post-inversion path  18   b , the medium  12  fed with the first interval is transported at the first post-inversion speed, and the medium  12  fed with the second interval is transported at the second post-inversion speed. 
         [0067]    Among the pre-inversion speed, the first post-inversion speed, the second post-inversion speed, and the processing speed, the processing speed is fastest. The processing speed is approximately the same as the pre-inversion speed, or is a speed slower than the pre-inversion speed. The first post-inversion speed is slower than the pre-inversion speed, and the second post-inversion speed is slower than the first post-inversion speed (processing speed the pre-inversion speed&gt;first post-inversion speed&gt;second post-inversion speed). The transport speed of the medium  12  may satisfy the above-described inequality, the medium  12  may be transported at a constant speed in a section of a predetermined transport path, or the medium  12  may be transported while accelerating or decelerating. 
         [0068]    Next, an operation in a case where the print apparatus  11  performs printing will be described. 
         [0069]    In the following description, the media from the first sheet among the media  12  that are fed and transported to the feeding unit  22  are sequentially described as the first medium  12   a , the second medium  12   b , and the third medium  12   c , and the fourth medium  12  is described as the fourth medium  12   d.    
         [0070]    When the printing is performed, the control unit  71  controls driving of the feeding motor  28  and the second transport motor  55  according to whether or not the calculated unit adhesion amount is greater than the threshold value stored in the storage unit  73 . Furthermore, the control unit  71  drives the upstream side transport motor  29 , the first transport motor  53 , the first inversion motor  66 , the second inversion motor  69 , and the downstream side transport motor  38  in the rotation state. 
         [0071]    That is, the medium  12  is fed by the feeding unit  22 , and transported by the transport unit. In addition, the printing unit  24  performs the printing by ejecting the liquid on the medium  12  at a timing at which the medium  12  passes through between the printing unit  24  and the transport belt  31 . 
         [0072]    As described in  FIG. 4 , the first medium  12   a  transported at the pre-inversion speed along the upstream side transport path  17  is received to the introduction path  43  at approximately the same speed. When the introduction sensor  58  detects a leading end of the first medium  12   a , the control unit  71  positions the guide flap  59  at the first position P 1  by driving the solenoid  60 . 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  12   a  transported up to the first connection point B is brought into contact with the first regulation flap  61  such that the first regulation flap  61  is moved against the bias force of the bias member. That is, the first regulation flap  61  is moved to open the downstream end of the first branch path  44 . Therefore, the first medium  12   a  is fed at the pre-inversion speed along the first switchback path  48  by the first inversion roller pair  65  driven in the rotation state. When the first medium  12   a  passes through the first regulation flap  61 , the first regulation flap  61  is moved from a position at which the downstream end of the first branch path  44  is open to a position at which the downstream end is close. 
         [0073]    As described in  FIG. 5 , when the first inversion sensor  64  detects a trailing end of the first medium  12   a , the control unit  71  switches the first inversion motor  66  driven in the rotation state to the counter-rotation state. The first inversion unit  41  sends the first medium  12   a  from the first switchback path  48  to a first connection point B side at the post-inversion speed. In addition, at this time, the first regulation flap  61  guides the first medium  12   a  to the first inversion path  46 . That is, the first inversion unit  41  sends the first medium  12   a  fed from the first branch path  44  to the first inversion path  46  such that a direction of the first medium  12   a  is inverted (switchback). 
         [0074]    In addition, when the introduction sensor  58  detects a leading end of the second medium  12   b , the control unit  71  changes a position of the guide flap  59  by driving the solenoid  60 . That is, the control unit  71  moves the guide flap  59  positioned at the first position P 1  to the second position P 2 . The guide flap  59  guides the second medium  12   b  to the second branch path  45 . 
         [0075]    As described in  FIG. 6 , the first medium  12   a  inverted by the first inversion unit  41  is transported along the post-inversion path  18   b  at the post-inversion speed. When the first medium  12   a  passes through the first connection point B, the control unit  71  drives the first inversion motor  66  in the rotation state. In addition, when the second inversion sensor  67  detects a trailing end of the second medium  12   b , the control unit  71  drives the second inversion motor  69  in the counter-rotation state. That is, the second inversion unit  42  inverts the second medium  12   b  and sends the inverted second medium  12   b  along the second inversion path  47  at the post-inversion speed, similar to the first inversion unit  41 . 
         [0076]    It is preferable that the post-inversion speed at which the first inversion unit  41  sends the first medium  12   a  from the first switchback path  48  to the first connection point B side, and the post-inversion speed at which the second inversion unit  42  sends the second medium  12   b  from the second switchback path  49  to the second connection point C side be the same as each other. According to this configuration, in the transporting after each medium is inverted, it is possible to maintain an interval between a trailing end of the preceding medium and a leading end of the subsequent medium at a constant. 
         [0077]    Furthermore, when the introduction sensor  58  detects a leading end of the third medium  12   c , the control unit  71  changes a position of the guide flap  59  by driving the solenoid  60 . That is, the control unit  71  moves the guide flap  59  positioned at the second position P 2  to the first position P 1 . That is, the guide flap  59  alternately guides the transported medium  12  to the first branch path  44  and the second branch path  45 . 
         [0078]    As described in  FIG. 7 , the second medium  12   b  inverted in the second inversion unit  42  and sent to the second inversion path  47  is transported along the derivation path  50  through the join point D. At this time, the intermediate transport unit  52  transports the first medium  12   a  and the second medium  12   b  at the post-inversion speed slower than the pre-inversion speed. Therefore, intervals between the first medium  12   a  and the second medium  12   b  in the transport direction Y are smaller than those of a case where transporting along the pre-inversion path  18   a  at the pre-inversion speed. 
         [0079]    When the first inversion sensor  64  detects a trailing end of the third medium  12   c , the control unit  71  drives the first inversion motor  66  in the counter-rotation state, and sends the third medium  12   c  to the first inversion path  46 . In addition, when the introduction sensor  58  detects a leading end of the fourth medium  12   d , the control unit  71  drives the solenoid  60 , and changes a position of the guide flap  59  to the second position P 2 . 
         [0080]    The intermediate device  15  sequentially sends the media  12  from the first medium  12   a  that is received in advance to the post-processing device  14 . That is, the medium  12  is sent to the post-processing device  14  in a state where the printed front surface faces a gravity direction. In addition, since the downstream side transport unit  35  transports the medium  12  at the processing speed faster than the post-inversion speed, intervals between the media  12  become larger. The post-processing unit  36  performs a process such as stapling on the media  12  transported along the downstream side transport path  19 , and discharges the processed media to the discharge unit  37 . 
         [0081]    In the device main body  13 , an interval between a trailing end of the preceding medium  12  and a leading end of the subsequent medium  12  is set as an interval A. In addition, after the preceding medium  12  and the subsequent medium  12  are switched back in the intermediate device  15 , an interval between the trailing end of the preceding medium  12  and the leading end of the subsequent medium  12  is set as an interval B. In addition, when the trailing end of the preceding medium  12  passes through the downstream side transport roller pair  39  of the post-processing device  14 , the interval between the trailing end of the preceding medium  12  and the leading end of the subsequent medium  12  is set as an interval C. 
         [0082]    At this time, in each interval, the following inequalities are satisfied. 
         [0000]      Inequality 1: interval A&gt;interval C&gt;interval B, or 
         [0000]      Inequality 2: interval C&gt;interval A&gt;interval B 
         [0083]    A relationship of magnitude between the interval A and the interval C can be appropriately adopted based on the transport path of the apparatus. For example, in a case where it is necessary to sufficiently ensure the intervals between the media  12  in the device main body  13 , it is preferable that Inequality 1 be adopted. Meanwhile, in a case where a post-processing in the post-processing unit  36  of the post-processing device  14  is not sufficiently performed in the interval A, Inequality 2 may be adopted. Alternatively, if there are no problems in various processes in the apparatus, the interval A and the interval C may be the same. 
         [0084]    Even in any case, the interval B becomes smaller than the interval A and the interval C. With this, in the intermediate device  15 , since intervals between the media  12  can be decreased and the media can be transported at a speed slower than the transport speed before the switchback is performed, it is possible to ensure a time required for drying the medium  12  in the intermediate device  15 . 
         [0085]    By the way, in order to make the interval C larger than the interval B, the transport speed of the downstream side transport roller pair  39  may be faster than the transport speed of the transport roller pair (for example, second transport roller pair) of the intermediate device  15 . In this case, if a friction clutch or the like is provided in the transport roller pair of the intermediate device  15 , even in a situation in which a leading end of the medium  12  is nipped by the downstream side transport roller pair  39  such that the transport starts, since it is possible to reduce occurrence of back tension due to a portion of the medium  12  nipped by the transport roller pair of the intermediate device  15 , disturbance of the transport does not occur. 
         [0086]    A rotation speed of the downstream side transport roller pair  39  is faster than the rotation speed of the transport roller pair of the intermediate device  15 . Accordingly, the interval C is changed by a size of the transported medium  12  in a transport direction. That is, when the medium  12  is transported to be a long side of the medium  12  in parallel with the transport direction, in a case where A3 is transported and a case where A4 is transported, since a time accelerated by the downstream side transport roller pair  39  in the case of A3 increases, the interval C in the case where A3 is transported is larger than that of the case where A4 is transported. 
         [0087]    In this manner, according to the size the medium  12 , as the size increases in the transport direction, when the process of stapling a plurality of the media  12  with a stapler (pin) in the post-processing unit  36  or the like is performed, the reason why difference between intervals of the interval C is necessary is that lots of times required to align end portions of the plurality of the media  12  are required. That is, since a surface area of the medium  12  of A3 is increased compared to A4, a large amount of time is required for stapling the end portions that are processing portions due to the friction between the plural sheets of the media  12 . 
         [0088]    There is another regulation method for the interval A, the interval B, and the interval C. That is, for the interval A, it is possible to consider a difference time from a time in which the trailing end of the preceding medium  12  reaches, to a time in which a trailing end of the subsequent medium  12  reaches, as the interval A, with respect to the upstream side transport roller pair  30  of the device main body  13 . In addition, for the interval B, after the preceding medium  12  and the subsequent medium  12  are switched back at the same time, it is possible to consider the difference time from the time in which the trailing end of the preceding medium  12  reaches, to the time in which the trailing end of the subsequent medium  12  reaches, as the interval B, with respect to the join point D on the intermediate transport path  18 . In addition, for the interval C, it is possible to consider the difference time from the time during which the trailing end of the preceding medium  12  reaches, to the time during which the trailing end of the subsequent medium  12  reaches, as the interval C, with respect to the downstream side transport roller pair  39  of the post-processing device  14 . 
         [0089]    Besides, it is considered that there are various positions as a position to be a reference of intervals between the preceding medium  12  and the subsequent medium  12 . That is, for the interval A, the difference time from the time during which the trailing end of the preceding medium  12  reaches, to the time during which the trailing end of the subsequent medium  12  reaches, may be considered as the interval A with respect to the introduction sensor  58  positioned in the vicinity of a branch point A on the intermediate transport path  18 . In addition, for the interval B, a difference time from a time during which the trailing end of the preceding medium  12  reaches with respect to the first inversion sensor  64  of the first switchback path  48 , to a time during which the trailing end of the subsequent medium  12  reaches with respect to the second inversion sensor  67  of the second switchback path  49 , may be considered as the interval B. That is, the first switchback path  48  and the second switchback path  49  are paths for separately performing switchback on the preceding medium  12  and the subsequent medium  12  branched and transported from the branch point A, in a viewpoint of improving transport efficiency. Therefore, as a design concept of the intermediate transport path  18 , the first switchback path  48  and the second switchback path  49  are designed to be the same transport distance. In this manner, even if the preceding medium  12  and the subsequent medium  12  are branched and transported in different switchback paths, it is possible to appropriately manage the intervals between the preceding medium  12  and the subsequent medium  12  after the switchback is performed. Therefore, according to the transport path based on such a design concept, a reference position of the interval B may be different positions by using the first inversion sensor  64  and the second inversion sensor  67 . 
         [0090]    In the above description, at positions to be the reference of each interval, a time until the trailing end of the preceding medium  12  and the trailing end of the subsequent medium  12  pass through may be the interval. Instead of this, at positions to be the reference of each interval, a time until a leading end of the preceding medium  12  and a leading end of the subsequent medium  12  pass through may be the interval. 
         [0091]    By the way, a start point and an end point of physical intervals between the media  12  are different from each other before and after the switchback is performed on the first switchback path  48  or the second switchback path  49 . That is, if before the switchback is performed, an interval is between the trailing end of the preceding medium  12  and the leading end of the subsequent medium  12 . Meanwhile, if after the switchback is performed, the interval is between the trailing end of the preceding medium  12  after the switchback is performed and the leading end of the subsequent medium  12  after the switchback is performed. Furthermore, if the preceding medium  12  is at a timing after the switchback is performed and the subsequent medium  12  is at a timing before the switchback is performed, the interval between the media  12  is an interval between the trailing end of the preceding medium  12  after the switchback is performed and the leading end of the subsequent medium  12  after the switchback is performed. 
         [0092]    According to the embodiments, the following effect can be obtained. 
         [0093]    (1) The intermediate transport unit  52  transports the medium  12  before being inverted at the pre-inversion speed, and transports the medium  12  after being inverted in the first inversion unit  41  or the second inversion unit  42  at the post-inversion speed slower than the pre-inversion speed. Therefore, a time required for transporting along the post-inversion path  18   b  can be longer than a time required for transporting along the post-inversion path  18   b  at the pre-inversion speed. Accordingly, it is possible to ensure a required transport time while suppressing an increase in the size of the device. 
         [0094]    (2) In the post-processing unit  36  performing a process on the medium  12 , for example, when intervals between the plurality of media  12  to be transported decrease, there is a possibility that the next medium  12  is transported before completing processing on the medium  12  that is transported in advance and erroneous processing is performed. Accordingly, the downstream side transport unit  35  transports the medium  12  at the processing speed faster than the post-inversion speed along the downstream side transport path  19 . Therefore, even in a case where the intervals between the media  12  decrease in the course of being transported along the post-inversion path  18   b , it is possible to increase the intervals between the media  12 . 
         [0095]    (3) As the unit adhesion amount increases, the required transport time increases. Furthermore, as the transport speed of the medium  12  decreases, the intervals between the media  12  decrease. Accordingly, the interval between the media  12  at the time of feeding is changed according to the unit adhesion amount. Therefore, even in a case where the unit adhesion amount is high, it is possible to transport the medium  12  at a sufficiently slow transport speed while suppressing the occurrence of contamination or the like due to overlapping of the media  12 . 
         [0096]    (4) In a case where the medium  12  having a high unit adhesion amount and a large transport time is transported, the downstream side transport unit  35  transports the medium  12  at the second post-inversion speed slower than the first post-inversion speed along the post-inversion path  18   b . Therefore, it is possible to further increase a time required for transporting the medium along the post-inversion path  18   b , compared to a case where the medium  12  is transported at the first post-inversion speed. 
         [0097]    (5) Since the print apparatus  11  includes the device main body  13 , the post-processing device  14 , and the intermediate device  15 , it is possible to easily change a combination of the apparatus. Therefore, for example, by exchanging the post-processing device  14 , it is possible to easily change processing performed on the medium  12  by the post-processing unit  36 . 
         [0098]    (6) The medium  12  is dried while the medium is transported by the transport unit. Therefore, by lengthening the transport time according to the transport of the medium at the post-inversion speed slower than the pre-inversion path  18   a  along the post-inversion path  18   b , even if, for example, the curling occurs on the medium  12  according to printing, it is possible to discharge the medium  12  in a state where the curling is reduced. Accordingly, it is possible to reduce occurrence of media clogging and process failure generated in a case where, for example, the medium  12  in which the curling occurs, processed in the post-processing unit  36 . 
         [0099]    (7) By changing the intervals between the media  12  and the post-inversion speed when the feeding unit  22  feeds the medium  12  according to the unit adhesion amount, it is possible to reduce the overlapping of the media  12 . Accordingly, it is possible to reduce the occurrence of the media clogging due to contact between the media  12 . 
         [0100]    The embodiment may be modified as follows. 
         [0101]    In the embodiment, the inversion unit may be provided equal to or greater than three. 
         [0102]    In the embodiment, a motor for driving the second transport roller pair  56  positioned on the most downstream side in the transport direction Y may be provided separately. That is, a speed for sending the medium  12  from the post-inversion path  18   b  to the downstream side transport path  19  may be different from the post-inversion speed. For example, the intermediate transport unit  52  may send the medium  12  along the post-inversion path  18   b  at a feeding speed (example of fifth transport speed) faster than the first post-inversion speed (first modification example). It is preferable that the feeding speed be faster than the first post-inversion speed and the same as the processing speed or slower than the processing speed (processing speed≧feeding speed≧the pre-inversion speed&gt;first post-inversion speed&gt;second post-inversion speed). 
         [0103]    According to a first modification example, the medium  12  is transported at the first post-inversion speed along the post-inversion path  18   b , and sent from the post-inversion path  18   b  at the feeding speed faster than the first post-inversion speed. Therefore, for example, even in a case where the media  12  overlap each other at the time of transporting along the post-inversion path  18   b , it is possible to send the media along the post-inversion path  18   b  by separating the media  12  from each other. That is, the media  12  are separated from each other such that it is possible to transfer the separated media to the downstream side transport path  19 . 
         [0104]    In the embodiment, the intermediate transport unit  52  may transport the media along the post-inversion path  18   b  in a state where a part of the media  12  overlap each other. At this time, it is preferable that the overlapped portion be a margin that is not printed thereon. In a case where the medium  12  of the downstream side in the transport direction Y is drawn out by the downstream side transport unit  35  in a state where the overlapped portion is interposed between the second transport roller pair  56 , the driving roller and the driven roller constituting the second transport roller pair  56  are separated from each other. 
         [0105]    In the embodiment, the transport speed of the medium  12  on the upstream side transport path  17  and the pre-inversion path  18   a  may be different from each other. For example, the upstream side transport unit  23  may transport the medium  12  along the upstream side transport path  17  at a print speed slower than or faster than the pre-inversion speed. 
         [0106]    In the embodiment, the rollers on different paths may be driven by one motor. For example, the upstream side transport roller pair  30  may be driven by the first transport motor  53  without using the upstream side transport motor  29 . 
         [0107]    In the embodiment, the threshold value relating to the unit adhesion amount stored in the storage unit  73  may be set or selected according to an environment in which the print apparatus  11  is installed. That is, the curling that occurs in the printed medium  12  depends on an environment. Specifically, for example, in a low humidity environment, since an amount of moisture contained in the medium  12  before printing is small, it is likely that the curling accompanying the printing increases. In addition, in a low temperature, since fluidity of the liquid decreases and the liquid is difficult to evaporate, a time for reducing the curling is required. Accordingly, in an environment where it is difficult to reduce the curling, the threshold value may decrease. 
         [0108]    In the embodiment, a plurality of the threshold values relating to the unit adhesion amount may be set, and the intervals between the medium  12  fed by the feeding unit  22  and the post-inversion speed may be changed step by step. 
         [0109]    In the embodiment, the medium  12  may be transported along the post-inversion path  18   b  at the post-inversion speed (second transport speed) slower than the pre-inversion speed (first transport speed) regardless of the unit adhesion amount. That is, the second post-inversion speed may be not set. 
         [0110]    In the embodiment, the feeding unit  22  may feed the media  12  with the first interval by rotating the pickup roller  26  at a first rotation speed, and may feed the media  12  with the second interval larger than the first interval by rotating at a second rotation speed slower than the first rotation speed. 
         [0111]    In the embodiment, the feeding unit  22  may feed the medium  12  with a constant interval regardless of the unit adhesion amount. 
         [0112]    In the embodiment, the print apparatus  11  may not include the feeding unit  22 . For example, the print apparatus  11  may include a feeding outlet, and the upstream side transport unit  23  may transport the medium  12  inserted one at a time from the feeding outlet. That is, the print apparatus  11  may perform printing on the medium  12  fed from a feeding device provided separately from the print apparatus  11 . In addition, the feeding unit  22  may feed the medium  12  set in a feeding tray one at a time. 
         [0113]    In the embodiment, in the post-processing unit  36 , any processing such as a punching process for punching a hole in the medium  12 , a shifting process for discharging the medium  12  by shifting it by unit basis, a cutting process for cutting the medium  12 , a folding process for folding the medium  12 , a bookbinding process for binding the medium  12 , or a collating processing, may be performed. 
         [0114]    In the embodiment, the print apparatus  11  may be a configuration in which the post-processing device  14  is not included. 
         [0115]    Liquid can be arbitrarily selected if the liquid can be printed on the medium  12  by adhering the liquid to the medium  12 . The liquid may be in a state when the material is in a liquid phase, and may include a liquid material such as a liquid material having high or low viscosity, sol, gel water, other inorganic solvent, organic solvent, solution, liquid resin, and liquid metal (metallic melt). In addition, not only liquid as one state of a material but also a material in which particles of a functional material composed of solid matter such as a pigment or metal particles is dissolved, dispersed or mixed by a solvent, and the like are included. As a representative example of the liquid, there is ink. The ink includes various kinds of liquid compositions such as general water-based ink, oil-based ink, gel ink, and hot melt ink. 
         [0116]    The medium  12  may be papers, resins, metals, clothes, ceramics, rubbers, natural materials (wood, stone, and the like), or a composite thereof. A thickness of the medium may be as a plate, a sheet, a film, a foil, or the like. Furthermore, a shape of the medium may be any shape such as a rectangle and a circle. That is, for example, a composite film of papers and resins (resin impregnated paper, resin coated paper, and the like), a composite film of resins and metals (laminate film), woven fabrics, non-woven fabrics, disk, circuit boards, and the like may be used. In a case of a medium which swells by adhering liquid such as papers, it is possible to reduce the curling while being transported along the intermediate transport path  18 . In addition, in a case of a medium which does not swell, it is possible to dry the medium while being transported along the intermediate transport path  18  although the curling does not occur. Accordingly, it is possible to appropriately process the medium  12  transported along the intermediate transport path  18  in the post-processing unit  36 . 
         [0117]    The print apparatus  11  is an apparatus that prints images such as letters, pictures, and photographs by adhering liquid such as the ink to a medium, and may also be as a serial printer, a lateral type printer, a line printer, a page printer, or the like. In addition, the print apparatus may be as an offset print apparatus, and a textile print apparatus. In addition, the print apparatus may have at least a print function of printing on a medium, and may also be a multifunction peripheral having functions other than the print function. 
         [0118]    The entire disclosure of Japanese Patent Application No.: 2016-009540, filed Jan. 21, 2016 and Application No.: 2017-003963, filed Jan. 13, 2017 are expressly incorporated by reference herein.