Patent Publication Number: US-10787336-B2

Title: Stacker and processing apparatus

Description:
INCORPORATION BY REFERENCE 
     The entire disclosure of Japanese Patent Application No. 2017-167358, filed Aug. 31, 2017 is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a stacker and a processing apparatus. The stacker is disposed at an ejection opening of the processing apparatus and causes media to be ejected through the ejection opening to be stacked and placed. 
     2. Related Art 
     Examples of such a stacker include those of, for example, JP-A-11-199113 and JP-A-10-194553. These documents describe a structure that includes a support member with which sheets ejected through an ejection opening of a printer are inclined upward and stacked. Here, the support member is positioned, instead of being positioned close to the ejection opening, so as to be largely separated from the ejection opening of the printer. The position of the support member is fixed. A conveyor belt is disposed between the ejection opening of the printer and the support member. The conveyor belt is downwardly inclined toward the downstream side in a feeding direction. The sheets are substantially horizontally ejected onto the conveyor belt, transported by the conveyor belt to the position of the support member, and stacked so as to be upwardly inclined. 
     In the above-described related-art stackers, the support member is fixed at the position largely separated from the ejection opening of a processing apparatus such as a printer instead of being positioned close to the ejection opening of the processing apparatus. This allows a larger amount of media to be stacked. However, since the position of the support member is fixed, the conveyor is necessary for transportation of the media to the separated position of the support member. Thus, there arises a problem in that the entirety of the stacker is increased in size. Furthermore, transportation by the conveyor belt is added. This arises a problem in that control of transport operation for stacking becomes complex. 
     SUMMARY 
     An advantage of some aspects of the disclosure is that an increase in size of a stacker can be suppressed while the amount of media to be stacked can be increased. 
     In order to obtain the above-described advantage, a stacker according to a first aspect of the disclosure is disposed at an ejection opening of a processing apparatus and causes media ejected through the ejection opening to be stacked and placed on a stacking surface. The stacker includes a support member, a receding mechanism, and a position maintaining mechanism. The support member is movable toward an upstream side and a downstream side in an ejecting direction, receives each of the media ejected through the ejection opening, and supports the medium in such an orientation that the medium is inclined with an end edge of the medium on the downstream side in the ejecting direction positioned above an end edge of the medium on the upstream side in the ejecting direction and that the end edge of the medium on the upstream side in the ejecting direction abuts the stacking surface. The receding mechanism causes the support member to recede toward the downstream side. The position maintaining mechanism maintains a position of the support member having been moved by the receding mechanism. 
     According to the first aspect, the support member that supports the media in an upwardly inclined orientation, that is, in a standing orientation is movable toward the upstream side and the downstream side in the ejection direction. Furthermore, the receding mechanism can cause the support member to recede toward the downstream side, and the position maintaining mechanism can maintain the position of the support member having receded by the specified distance, that is the position maintaining mechanism can hold the support member at this position. Thus, when the medium is supported by the support member so as to be in the standing orientation, the support member recedes by the specified distance and is kept at the position to which the support member has receded. This can ensure a space to support the next medium. 
     Accordingly, when 
     1. the receding of the support member by the specified distance, 
     2. operation to support the medium in the standing orientation at the support space for the medium ensured by the receding, and 
     3. the next receding are sequentially repeatedly performed, the increase in size of the stacker can be suppressed while the amount of media to be stacked can be increased. 
     Here, the term “maintain the position of the support member” means that the support member is held at the position to which the support member has been moved by the receding mechanism. However, this does not necessarily mean that the support member does not move at all. The position of the support member may move at low speed as long as a technical significance of the above-described term “maintain the position” (a state in which operation for supporting the next medium in the standing orientation can be performed at the support space for the media obtained by the receding) is substantially satisfied. 
     It is preferable that the position maintaining mechanism include a pulling mechanism that applies to the support member a pulling force to pull toward the upstream side and a suppressing mechanism that suppresses the pulling force at a position to which the support member has been caused to recede by a specified distance by the receding mechanism. 
     Here, the term “suppresses the pulling force” means canceling of the pulling force so as to maintain the support member at the position or reduction of the pulling force. 
     Thus, the position maintaining mechanism that maintains the position of the support member having been moved by the receding mechanism can be realized with a simple structure. 
     It is preferable that, in order to recede the support member, the receding mechanism apply a moving force to move against a frictional force caused by frictional resistance with the stacking surface which serves as a surface sliding against the support member. In this case, the position maintaining mechanism maintains the position of the support member by utilizing the frictional resistance. 
     Thus, the position of the support member having been moved by the receding mechanism is maintained at the position by utilizing the frictional force of the sliding surface. Accordingly, the position maintaining mechanism can be realized with a simple structure in which the constant force spring or the like is not used. 
     It is preferable that stacker further include a transport roller that receives the medium ejected through the ejection opening and that transports the medium toward the downstream side. In this case, the transport roller is driven by transmitting motive power with which the processing apparatus ejects the medium. 
     Thus, the stacker includes the transport roller that transports toward the downstream side the medium ejected through the ejection opening. By setting the transport roller as a base point of a medium transport path of the stacker, the design of the medium transport path and transport control can be simply performed. 
     Furthermore, the transport roller is driven by utilizing the motive power of the processing apparatus for the ejection. Accordingly, no dedicated motive power source is required. 
     It is preferable that the transport roller be driven by transmitting the motive power from a rotation shaft of an ejection roller positioned at a most downstream portion of the processing apparatus in the ejecting direction. 
     Thus, the motive power is transmitted to the transport roller from the rotation shaft of the ejection roller positioned at the most downstream portion near the ejection opening on the processing apparatus side. This allows the motive power transmission structure to be realized with a simple structure. 
     It is preferable that the receding mechanism include an advancing/retreating member provided on a rotation shaft of the transport roller. In this case, the advancing/retreating member repeatedly performs, linked with the rotation of the rotation shaft of the transport roller, pushing of the support member and retreating from the support member. 
     Thus, the advancing/retreating member provided on the rotation shaft of the transport roller repeatedly performs, linked with the rotation of the rotation shaft of the transport roller, pushing of the support member and retreating from the support member. This allows the receding mechanism to be realized with a simple structure. Furthermore, the receding of the support member by the specified distance can be performed by the “pushing” with the advancing/retreating member, and the operation to ensure the support space for the medium through the receding of the support member can be performed by the “retreating”. 
     It is preferable that the receding mechanism include a first cam member provided on the rotation shaft of the transport roller. In this case, the first cam member causes, linked with the rotation of the rotation shaft of the transport roller, the advancing/retreating member to perform the pushing and the retreating. 
     Thus, the pushing and the retreating by the advancing/retreating member can be realized with a simple structure by using the first cam member provided on the rotation shaft of the transport roller. 
     It is preferable that the stacker further include a nipping member that, together with the transport roller, nips the medium therebetween so as to transmit a transport force of the transport roller to the medium while the medium is being nipped. In this case, the nipping is released when the advancing/retreating member performs the pushing. 
     Thus, the nipping performed by the nipping member paired with the transport roller so as to transmit the transport force to the medium is released while the advancing/retreating member is performing the pushing. Thus, the transport force is not transmitted to the medium while the pushing is being performed. Accordingly, during the operation to ensure the support space for the medium through the receding, the medium is not fed into the support space by the “pushing” of the advancing/retreating member. This can reduce the likelihood of jamming or creasing of the medium. 
     It is preferable that the nipping member be able to be displaced between a position at which the nipping member together with the transport roller performs the nipping and a position at which the nipping is released, and a second cam member be provided on the rotation shaft of the transport roller. In this case, the second cam member causes, linked with the rotation of the rotation shaft of the transport roller, the nipping member to be displaced. 
     Thus, the second cam member provided on the rotation shaft of the transport roller causes the nipping member to be displaced between the position at which the nipping member performs the nipping and the position at which the nipping is released. Accordingly, the nipping can be released with a simple structure. 
     It is preferable that the pulling mechanism be a constant force spring, and the suppressing mechanism be a regulating portion that regulates rotation of the constant force spring in a direction in which the constant force spring is wound. 
     Thus, the position maintaining mechanism can be easily realized with the constant force spring. 
     It is preferable that the stacker be a unitized device that is removably mountable in the processing apparatus. 
     Thus, the stacker is the unitized device that is removably mountable in the processing apparatus. Accordingly, stacking with the stacker and stacking performed by the processing apparatus itself without the stacker can be switched. 
     In particular, when the transport roller is driven by transmitting the motive power from a rotation shaft of the ejection roller positioned at the most downstream portion of the processing apparatus in the ejecting direction as has been described, the motive power on the processing apparatus side can be easily utilized with the structure in which the unitized stacker can be set in alignment with the ejection opening of the processing apparatus. 
     A processing apparatus according to a second aspect of the disclosure includes a processing unit, an ejection mechanism, and a stacker unit. The processing unit performs a specified process on media. The ejection mechanism ejects through an ejection opening the media transported thereto through the processing unit. The stacker unit receives the media ejected through the ejection opening and stacks the media. In this case, the stacker unit is any one form of the above-described stacker. 
     Thus, the processing apparatus can obtain the effects produced by any one form of the stacker. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a perspective view of an example of a processing apparatus according to an embodiment of the disclosure seen from a diagonally front right side. 
         FIG. 2  is a perspective view of the example of the processing apparatus according to the embodiment seen from a diagonally front left side. 
         FIG. 3  is a front view of the example of the processing apparatus according to the embodiment. 
         FIG. 4  is a perspective view illustrating a state in which a stacker is disposed in an ejection unit of the processing apparatus according to the embodiment. 
         FIG. 5  is a perspective view illustrating a use state of the ejection unit of the processing apparatus according to the embodiment. 
         FIG. 6  is a perspective view of the stacker according to the embodiment seen from a diagonally rear left side. 
         FIG. 7  is a perspective view of the stacker according to the embodiment seen from a diagonally front left side. 
         FIG. 8  is a perspective view of the stacker according to the embodiment seen from a diagonally front right side. 
         FIG. 9  is a perspective view of a power transmission unit of the stacker according to the embodiment. 
         FIG. 10  is a perspective view of a receding mechanism and a position maintaining mechanism of the stacker according to the embodiment seen from a diagonally front right side. 
         FIG. 11  is a perspective view of the receding mechanism and the position maintaining mechanism of the stacker according to the embodiment seen from a diagonally front left side. 
         FIG. 12A  is a perspective view of the receding mechanism illustrating operation of the stacker according to the embodiment, specifically illustrating a state in which an advancing/retreating member has been retreated. 
         FIG. 12B  is a perspective view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member is being pushed. 
         FIG. 12C  is a perspective view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member has been pushed. 
         FIG. 12D  is a perspective view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member is retreating. 
         FIG. 13  is a perspective view of the support member and the position maintaining mechanism of the stacker according to the embodiment seen from a diagonally upper left side. 
         FIG. 14  is a perspective view of the support member and the position maintaining mechanism of the stacker according to the embodiment seen from a diagonally lower left side. 
         FIG. 15  is a side sectional view of the stacker according to the embodiment with the support member positioned at a maximum stack position. 
         FIG. 16  is a side sectional view of the stacker according to the embodiment with the support member positioned at a stack start position. 
         FIG. 17A  is a side view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member has been retreated. 
         FIG. 17B  is a side view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member is being pushed. 
         FIG. 17C  is a side view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member has been pushed. 
         FIG. 17D  is a side view of the receding mechanism illustrating the operation of the stacker according to the embodiment, specifically illustrating a state in which the advancing/retreating member is retreating. 
         FIG. 18A  is a side sectional view illustrating the operation of the stacker according to the embodiment with a regulating portion set in a regulating state. 
         FIG. 18B  is a side sectional view illustrating the operation of the stacker according to the embodiment with the regulating portion set in a regulation release state. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     With a multi-functional ink jet printer that includes stacking-type medium cassettes, a medium feed tray for manual feeding, and a medium ejection tray for manual ejection as an example of a processing apparatus according to an embodiment of the disclosure, the structure of the processing apparatus according to the embodiment of the disclosure, the structure of a stacker according to the embodiment of the disclosure used for the medium ejection tray of the processing apparatus, and forms of operation of the processing apparatus mainly including operation of the stacker will be described in detail below with reference to the accompanying drawings. 
     In the following description, first, an outline of the overall structure of the processing apparatus according to the embodiment of the disclosure is described based on  FIGS. 1 to 3 . Next, the structure of an ejection unit is briefly described. The ejection unit includes the medium ejection tray for which the stacker according to the embodiment of the disclosure is used and members around the medium ejection tray. Next, the structure of the stacker according to the embodiment of the disclosure used for the medium ejection tray is specifically described. After that, the forms of operation of the processing apparatus according to the embodiment of the disclosure mainly including operation of the stacker are described. Finally, reference is made to the structures of other embodiments that are partially different from the structure of the embodiment are referred. 
     1. The Outline of the Overall Structure of the Processing Apparatus (with Reference to  FIGS. 1 to 3 ) 
     A processing apparatus  1  illustrated in the drawings is a multi-functional ink jet printer that includes a scanner unit  3 , medium cassettes  5 A to  5 D, a medium feed tray  7 , and a medium ejection tray  8 . The scanner unit  3  is disposed in an upper portion of an apparatus main body  2 . For example, four medium cassettes  5 A to  5 D are disposed in a lower portion of the apparatus main body  2 . The medium cassettes  5 A to  5 D are stacked one on top of another. The medium feed tray  7  is disposed in, for example, a right side surface of the apparatus main body  2 . The medium feed tray  7  is used for manual feeding. The medium ejection tray  8  is disposed in, for example, a left side surface of the apparatus main body  2 . The medium ejection tray  8  is used for manual ejection. 
     Furthermore, a display/operating panel  9  is provided, for example, on the left-hand side of an upper portion of the apparatus main body  2  as viewed from the front. The display/operating panel  9  is for setting various items and performing operations of the processing apparatus  1 . A comparatively large space A is formed, for example, on the right-hand side of the display/operating panel  9  as viewed from the front. Media P which have been fed from the medium cassettes  5 A to  5 D and on which processes have been performed are received in the space A in a face placement orientation. The bottom of the space A is an ejection stacker  11 . 
     Furthermore, a standard-equipment medium cassette  5 A is provided uppermost in the stacked medium cassettes  5 A to  5 D in a lower portion of the apparatus main body  2 . Three additional medium cassettes  5 B to  5 D are provided below the medium cassette  5 A. Furthermore, the medium feed tray  7  of, for example, an opening/closing lid type for manual feeding is provided in, for example, the right side surface of the apparatus main body  2  as viewed from the front. Furthermore, the medium ejection tray  8  of, for example, an opening/closing lid type for manual ejection is provided in, for example, the left side surface of the apparatus main body  2  as viewed from the front. 
     Furthermore, the apparatus main body  2  includes therein a processing unit  13 , a transport unit  17 , an ejection unit  10 , and a controller  19 . The processing unit  13  performs specified printing processes by ejecting droplets of colors (for example, four colors including cyan (C), magenta (M), yellow (Y), and black (K)) to each of the media P having been fed from one of the medium cassettes  5 A to  5 D or the medium feed tray  7 . The transport unit  17  transports the media P toward a processing region  15  of the processing unit  13 . The ejection unit  10  ejects to the outside of the apparatus main body  2  the media P which have been fed from the medium feed tray  7  and on which processes have been performed. The controller  19  controls various operations of the processing unit  13 , the transport unit  17 , and the ejection unit  10 , items displayed in the display/operating panel  9 , and so forth by receiving information from the display/operating panel  9  and external devices such as a personal computer (PC) and the like. 
     As the processing unit  13 , a so-called line-head-type processing head is provided. The line-head-type processing head performs a process (for example, recording) in a width direction X of each of the media P entirely at a time. This process is performed at a fixed feed pitch. The width direction X intersects a direction Y in which the media P are transported. 
     Of course, in the case where the quality of processing is considered as more important than the processing speed for the processing apparatus  1 , a so-called serial-head-type processing head can be used. The serial-head-type processing head is mounted on a carriage (not illustrated) and is reciprocated in the width direction X so as to perform a specified process. 
     A transport unit into which is, for example, the following components are unitized is used as the transport unit  17 : nipping transport rollers that transport toward the processing region  15  or the ejection unit  10 , which will be described later, the media P having fed by feeding rollers (not illustrated); motors that drive these components; gear trains, belts, and so forth; guide rollers and guide plates that guide transportation of the media P; and a reverse mechanism that reverses the transport direction. 
     The processing apparatus  1  according to the present embodiment is basically a structured with the processing unit  13 , an ejection mechanism  18  ( FIG. 9 ), and a stacker  21  (stacker unit) included therein. The processing unit  13  performs specified processes on the media P. The ejection mechanism  18  ejects through an ejection opening  20  the media transported thereto through the processing unit  13 . The stacker  21 , which will be described later, receives media P ejected through the ejection opening  20  and stacks the received media P one on top of another. 
     Furthermore, according to the present embodiment, the unitized stacker  21  removably disposed in the ejection unit  10  of the processing apparatus  1  is used. 
     Herein, “face placement orientation”, which may alternatively be referred to as “lying orientation”, refers to an orientation in which the media P are stacked such that the faces of the media P are horizontally placed along a placement surface  23  of the medium ejection tray  8 , and “edge placement orientation”, which may alternatively be referred to as “standing orientation”, refers to an orientation in which the media P are stacked such that the edges of a plurality of the media P are in contact with a stacking surface  22  of the stacker  21 , which will be described later, that is, the media P stand erect. 
     Accordingly, compared to a method of using only with the medium ejection tray  8  on which media P are stacked in the face placement orientation (lying orientation), it is possible to significantly increase the number of the media P that can be stacked by using the stacker  21  that allows a large number of the media P to be stacked in the edge placement orientation (standing orientation). 
     2. The Structure of the Ejection Unit (with Reference to  FIGS. 4, 5, and 9 ) 
     For example, the ejection unit  10  includes the ejection opening  20 , the medium ejection tray  8 , and ejection rollers  18  ( FIG. 9 ). The ejection opening  20  is formed in, for example, the left side surface of the apparatus main body  2 . The medium ejection tray  8  openably closes the ejection opening  20 . The ejection rollers  18  are provided on the apparatus main body  2  side so as to face the ejection opening  20  and serve as elements of the ejection mechanism. 
     The ejection opening  20  has a rectangular window shape elongated in the width direction X. The ejection opening  20  has a recessed space extending slightly inward from the side surface of the apparatus main body  2 . The medium ejection tray  8  has pivot supports (not illustrated) disposed at lower portions of inner surfaces at both end portions in the width direction X in the recessed space. The medium ejection tray  8  is pivotable about the pivot supports between a position where the medium ejection tray  8  is in a closed state in which the medium ejection tray  8  closes the ejection opening  20  formed in the side surface of the apparatus main body  2  while being parallel to this side surfaces and a position where the medium ejection tray  8  is in an open state in which the medium ejection tray  8  is opened so as to expose the ejection opening  20  while the medium ejection tray  8  intersects this side surface at an angle θ ( FIG. 15 ). 
     According to the illustrated embodiment, the angle θ at which the medium ejection tray  8  intersects the side surface is set to, for example, about 80°. Due to this setting, the placement surface  23  of the medium ejection tray  8  extending toward the downstream side in a direction Y in which the media P is ejected becomes an upward inclination of about 10°. 
     A handle (not illustrated) is provided in a front surface of the medium ejection tray  8 . A user holds this handle to cause the medium ejection tray  8  to pivot. A rear surface of the medium ejection tray  8  is the placement surface  23  on which the media P is placed in the face placement orientation (lying orientation). An extension tray  29  is connected to the medium ejection tray  8  at a distal end portion of the medium ejection tray  8 . The extension tray  29  can be drawn out in the direction Y in which the media P is ejected and retracted in the opposite direction. Although it is not illustrated, the placement surface  23  of the medium ejection tray  8  has, for example, a recess, and a base frame  37  of the stacker  21 , which will be described later, has, for example, a projection at its bottom surface. With this structure, positioning in a planar direction XY parallel to the placement surface  23  is performed by fitting the projection into the recess. 
     As illustrated in  FIG. 9 , a plurality of (six according to the illustrated embodiment) the ejection rollers  18 , which is, as examples, formed of rubber, are disposed on a shaft  25  horizontally extending in the width direction X such that the ejection rollers  18  are appropriately spaced from one another in the width direction X. Motive power is transmitted from, for example, the transport unit  17  in the apparatus main body  2  to the shaft  25  so as to rotate the shaft  25  in an ejection direction Y in which the medium P is ejected. 
     Furthermore, the stacker  21 , which will be described next, is not particularly provided with a motive power source. The stacker  21  performs specified operations by receiving motive power from the ejection rollers  18  rotated together with the shaft  25 . 
     3. The Structure of the Stacker (with Reference to  FIGS. 6 to 11 and 13 to 16 ) 
     According to the present embodiment, the stacker  21  is provided at the ejection opening  20  of the processing apparatus  1  and stacks the media P ejected through the ejection opening  20 . The media P are stacked in the direction Y in which the media P is ejected. The media P stacked are in the edge placement orientation (standing orientation). 
     The stacker  21  basically includes a support member  53 , a receding mechanism  111 , and a position maintaining mechanism  56 . The support member  53  is movable toward the upstream side and the downstream side in the ejecting direction Y, receives the media P ejected through the ejection opening  20 , and supports the media P such that the media P are inclined upward at an inclination angle α ( FIG. 15 ). The receding mechanism  111  ( FIGS. 7 to 12D ) causes the support member  53  to recede toward the downstream side in the ejecting direction Y. The position maintaining mechanism  56  ( FIGS. 6 and 9 to 14 ) that maintains the position of the support member  53  having been moved by the receding mechanism  111 . 
     The Position Maintaining Mechanism 
     As illustrated in  FIGS. 13 to 16 and 18A to 18D , the position maintaining mechanism  56  includes a pulling mechanism  57  and a suppressing mechanism  58 . The pulling mechanism  57  causes a force F ( FIG. 15 ) that pulls toward the upstream side in the ejecting direction Y to act on the support member  53 . The suppressing mechanism  58  ( FIG. 14 ) suppresses the pulling force F at a position to which the support member  53  has caused to recede by the receding mechanism  111  by a specified distance S ( FIGS. 12C, 15, and 17C ). 
     Here, the term “suppresses the pulling force F” means both the following operations: maintaining the support member  53  at the position by causing a force the magnitude of which is the same as the pulling force F and which is oppositely directed to the pulling force F to act so as to cancel the pulling force F; and causing a force the magnitude of which is not the same as the pulling force F and which is oppositely directed to the pulling force F to act so as to reduce the pulling force F. 
     As illustrated in  FIGS. 6 and 7 , the stacker  21  includes the base frame  37  having a substantially rectangular plate shape. Various components to be described below are provided on an upper surface of the base frame  37 . 
     First, a pair of side guide portions  41 L and  41 R (simply denoted as “41” in some cases) are provided near respective side end portions of the base frame  37  in the width direction X. The side guide portions  41 L and  41 R guide the respective side edges of the media P, the side edges located at the sides in the X direction. Here, the media P is to be stacked in the edge placement orientation (standing orientation). For example, the side guide portions  41 L and  41 R can be moved toward/separated from each other over a specified stroke in the width direction X. The distance between the left and right side guide portions  41 L and  41 R is adjusted within the length of elongated holes  43  formed as examples in the base frame  37 . The side guide portions  41 L and  41 R are fixed at respective positions by tightening fixing screws  45  as examples having knobs at the heads thereof. Two fixing screws  45  are provided at each side in the width direction X, that is, a total of four fixing screws  45  are provided. 
     The side guide portions  41 L and  41 R are formed by, for example, bending thin metal sheets into a U shape. Upper bent portions that project outward serve as handle portions  47  to be held by hands for operation when adjusting the distance between the side guide portions  41 L and  41 R. Furthermore, lower bent portions serve as base plates  49  in contact with the upper surface of the base frame  37  so as to hold the side guide portions  41 L and  41 R in a standing position. 
     Furthermore, in the ejecting direction Y, the length of the side guide portions  41 L and  41 R is slightly smaller than the length of the base frame  37 . A member of a transportation system, which will be described later, the receding mechanism  111  that cooperates with the transport system member, and elements of a nip release mechanism  106  ( FIGS. 11 and 12A to 12D ), which will be described later, are disposed in a space upstream of the side guide portions  41 L and  41 R in the ejecting direction Y. The transport system member reorients the ejected media P in the face placement orientation (lying orientation) so that the media P assume the edge placement orientation (standing orientation) and feed the media P to a stacking region  27  of the stacker  21 . 
     Meanwhile, in a space downstream of the side guide portions  41 L and  41 R in the ejecting direction Y, a guide scale  51  ( FIG. 6 ) and an accommodating space are formed. The guide scale  51  serves as a guide when the distance between the side guide portions  41 L and  41 R is adjusted. The accommodating space accommodates the support member  53  having moved to a maximum stacking position. The support member  53  will be described later. 
     In addition to the above-described guide scale  51 , guide scales  51  are also formed beside upstream end portions of the side guide portions  41 L and  41 R in the ejecting direction Y. Spaces obtained by cutting parts of the base plates  49  are utilized for these guide scales  51 . 
     Furthermore, the height of guide side plates  55  that connect the handle portions  47  and the base plates  49  of the side guide portions  41 L and  41 R to one another is large on the upstream side and small in the downstream side in the ejecting direction Y. That is, the side guide portions  41 L and  41 R are set such that the guiding distance is larger on the upstream side where the media P ejected from the processing apparatus  1  are placed on the stacker  21  than on the downstream side where media P are removed from the stacker  21 . 
     This improves performance with which the media P are aligned in a region on the upstream side of the side guide portions  41 L and  41 R and improves performance with which the media P are removed in a region on the downstream side of the side guide portions  41 L and  41 R. 
     The support member  53  includes a support plate  59  and a slide block  61 . The support plate  59  supports the media P in such an orientation that the media P are inclined toward the downstream side with upper portions thereof are further in the ejecting direction Y than lower portions thereof. The slide block  61  supports the support plate  59  such that the support plate  59  is movable toward the upstream side and the downstream side in the ejecting direction Y. According to the present embodiment, the support plate  59  is inclined at, for example, an inclination angle α ( FIG. 15 ) of about 60° relative to the stacking surface  22  of the stacker  21 . The stacking surface  22  is part of the upper surface of the base frame  37 , the left and right sides of which are defined by the side guide portions  41 L and  41 R and the surface of which on the downstream side in the ejecting direction Y is defined by the support plate  59 . 
     The slide block  61  includes a projection  65 , a winding mechanism  67  ( FIGS. 6, 13, and 14 ), a regulating portion  58 , a regulation release lever  60  ( FIGS. 6, 15, and 16 ), and so forth. The projection  65  ( FIG. 15 ) is provided in a lower surface of the slide block  61  and engaged with a guide hole  63  ( FIG. 7 ) extending in the ejecting direction Y at the center of the base frame  37  in the width direction X. The winding mechanism  67  ( FIGS. 6, 13, and 14 ) is provided in the slide block  61  and for a constant force spring  57  (denoted by the same reference sign as that of the pulling mechanism) included in the pulling mechanism  57 . The regulating portion  58  ( FIG. 14 ) is included in the suppressing mechanism. The regulation release lever  60  ( FIGS. 6, 15, and 16 ) is operated in order to release a stated regulated by the regulating portion  58 . 
     The Transport System Member 
     Next, the transport system member is described. As has been described, the stacker  21  according to the present embodiment moves the media P to the stacking region  27  by driving the transport system member, which is described below, by using the rotation of the ejection rollers  18  of the processing apparatus  1  as a motive power source. 
     As the transport system member, a transport roller  75  (for example,  FIG. 7 ) is provided. The transport roller  75  applies a feeding force to the media P ejected by the ejection rollers  18  to the outside of the apparatus main body  2 . The transport roller  75  is attached to a rotation shaft  99  supported by a support frame  137  provided in a space on the upstream side of the base frame  37  in the ejecting direction Y. The transport roller  75  is located, for example, at the center in the stacker  21  in the width direction X. 
     The transport roller  75  paired with a nipping member  107  (for example,  FIG. 8 ) provided below the transport roller  75  nips the supplied media P, thereby applying the feeding force to the media P. As illustrated in  FIGS. 10 and 11 , the nipping member  107  includes a plate-shaped member that substantially horizontally extends toward the downstream side in the ejecting direction Y from a bent portion where the nipping member  107  is bent downward. The bent portion is disposed at an end portion on the upstream side in the ejecting direction Y where a pivot shaft  129  is integrally fixed with a fixing screw  130 . 
     For example, a nipping roller  109  ( FIGS. 15 to 17D ) is provided at an end portion of the nipping member  107  on the downstream side in the ejecting direction Y. This end portion is a pivot free end of the nipping member  107 . The nipping roller  109  is brought into contact with the transport roller  75  for nipping operation. 
     Furthermore, retaining claws  108  are provided at a lower end of the downwardly bent portion on the upstream side of the nipping member  107 . The retaining claws  108  outwardly project to the left and right in the width direction X. A spring  131  ( FIGS. 10 to 12D ) is attached to each of the retaining claws  108 . The spring  131  performs pushing so that the pivot free end of the nipping member  107  is constantly displaced toward the transport roller  75 . 
     The nipping roller  109  is a preferable structure for smooth transportation of the media P. However, the nipping roller  109  may be omitted when a sufficient feeding force can be obtained only by a contact of the transport roller  75  with the pivot free end of the nipping member  107 . 
     A Power Transmission Unit 
     Next, based on  FIGS. 6 to 9 , the structure of a power transmission unit  77  is described. The power transmission unit  77  transmits the motive power of the ejection rollers  18  to the transport roller  75 . Out of, for example, six of the ejection rollers  18  provided on the shaft  25 , the power transmission unit  77  utilizes, for example, ejection rollers  18 L and  18 R (simply denoted as “18” in some cases) that are a second ejection roller  18  from the left end and a second ejection roller  18  from the right end in the width direction X, respectively, to transmit the motive power ( FIG. 9 ). 
     Specifically, the power transmission unit  77  includes, for example, transmission rollers  79 L and  79 R, first transmission gears  83 , intermediate gears  85 , a second transmission gear  89 , an input pulley  93 , and an output pulley  97 . The transmission rollers  79 L and  79 R (simply denoted as “ 79 ” in some cases) abut the ejection rollers  18 L and  18 R, thereby the rotation is first transmitted to the transmission rollers  79 L and  79 R. The first transmission gears  83  are provided on the shaft  81 , on which the transmission rollers  79 L and  79 R are provided, and rotated together with the transmission rollers  79 L and  79 R. The intermediate gears  85  are engaged with the first transmission gears  83  and rotated about a shaft  87 . The second transmission gear  89  is engaged with one of the intermediate gears  85 . The input pulley  93  is provided on a shaft  91 , on which the second transmission gear  89  is provided, and rotated together with the second transmission gear  89 . The rotation of the input pulley  93  is transmitted via a toothed timing belt  95  to the output pulley  97  provided on the rotation shaft  99 , on which the transport roller  75  is provided. Thus, the output pulley  97  is rotated together with the transport roller  75 . 
     Furthermore, according to the present embodiment, the transport roller  75  is rotated in the opposite direction to the rotation direction of the ejection rollers  18  and rotated at the same speed as the rotation speed of the ejection rollers  18 . Thus, the media P are smoothly moved and transported to the stacker  21 . 
     Lifting-Off Suppressing Members 
     Next, based on  FIGS. 6 to 9 , lifting-off suppressing members  133 L and  133 R (simply denoted as “133” in some cases) are described. The lifting-off suppressing members  133 L and  133 R improve performance with which the media P is introduced by suppressing lifting-off of the media P caused by curl or the like of the media P occurring when the media P is moved to the stacker  21 . 
     That is, end edges of the guide side plates  55 L and  55 R (simply denoted as “ 55 ” in some cases) of the side guide portions  41 L and  41 R on the upstream side in the ejecting direction Y are inclined at the substantially same angle as the angle at which the support plate  59  of the support member  53  is inclined. The lifting-off suppressing members  133 L and  133 R are provided inside the inclined end edges. Each of the lifting-off suppressing members  133 L and  133 R has a substantially L shape in side view. 
     The lifting-off suppressing members  133 L and  133 R include inclined portions  134  and horizontal portions  135 . The inclined portions  134  are provided along the end edges of the guide side plates  55 L and  55 R of the side guide portions  41 L and  41 R on the upstream side in the ejecting direction Y. The horizontal portions  135  extend from the lower ends of the inclined portions  134  toward the upstream side in the ejecting direction Y so as to be continuous with the inclined portions  134  and parallel to the upper surface of the base frame  37 . Furthermore, end portions of the horizontal portions  135  on the upstream side in the ejecting direction Y slightly outwardly projects to the left and right in the width direction X so as to have a large width. Thus, entrance guides  136  having, for example, a U-shaped section are provided of portions functioning as slopes that guide the media P ejected to the end portions by the ejection rollers  18  so that misalignment in the width direction X is corrected and the media P comes to the center in the width direction X. 
     Furthermore, gaps having specified sizes are formed between each of the side edges of the medium P in the width direction X moved to the stacker  21  and transported and a rear surface of a corresponding one of the inclined portions  134  and between these edge of the medium P and a lower surface of a corresponding one of the horizontal portions  135 . Lifting-off and inclination of the medium P are regulated within the sizes of these gaps. Accordingly, even when a force that displaces an upper portion of the medium P having been transitioned to the edge placement orientation (standing orientation) toward the upstream side in the ejecting direction Y acts, the medium P is brought into contact with the rear surface of the inclined portion  134 , and the medium P that is lifted off or inclined larger than the sizes of the above-described gaps is restored to the original position. Thus, smooth transportation of the media P on the stacking surface  22  is maintained. 
     Furthermore, the support frame  137  has a sub-frame  141  at a top plate portion thereof. The sub-frame  141  extends downward and has a substantially L shape in section ( FIGS. 8 and 9 ). The sub-frame  141  has a side wall portion  143  perpendicular to the upper surface of the base frame  37  and a bottom plate portion parallel to the upper surface of the base frame  37 . The bottom plate portion serves as a suppressing plate  139  that suppresses lifting-off or bulging in the central portion of the medium P in the width direction X being moved to the stacker  21 . 
     The position where the suppressing plate  139  is provided is set upstream of the transport roller  75  in the ejecting direction Y. An upstream end portion of the suppressing plate  139  is inclined slightly upward. This suppresses catching of the medium P by the suppressing plate  139  when the medium P is supplied with a large lifting-off formed therein. 
     Herein, in view of the above-described functions, the horizontal portions  135  of the lifting-off suppressing members  133 L and  133 R, the suppressing plate  139 , and the inclined portions  134  are separately defined as first lifting-off suppressors, a second lifting-off suppressor, and a third lifting-off suppressor, respectively. 
     The Receding Mechanism and an Advancing/Retreating Member 
     Next, based on  FIGS. 10 to 12D and 17A to 17D , the receding mechanism  111  is described. The receding mechanism  111  includes an advancing/retreating member  103  provided on the rotation shaft  99  of the transport roller  75 . The advancing/retreating member  103  repeatedly performs, linked with the rotation of the rotation shaft  99  of the transport roller  75 , pushing of the support member  53  and retreating from the support member  53 . 
     Furthermore, the receding mechanism  111  includes a first cam member  101  made integral with the rotation shaft  99  of the transport roller  75 . The first cam member  101  causes the advancing/retreating member  103  to perform, linked with the rotation of the rotation shaft  99  of the transport roller  75 , the pushing and the retreating. 
     The advancing/retreating member  103  has a flat plate shape elongated in the ejecting direction Y as illustrated in  FIGS. 10 and 11 . An end portion on the downstream side of the advancing/retreating member  103  in the ejecting direction Y has an arc shape ( FIGS. 17A to 17D ) having a large radius of curvature. This end portion serves as a pushing actuator  145  that abuts the support plate  59  of the support member  53  so as to cause the support member  53  to recede by a specified distance S (for example, 1 to 10 mm;  FIGS. 12C and 17C  to be referred to later). 
     Furthermore, the advancing/retreating member  103  has a first fitting elongated hole  117  ( FIG. 11 ) and a second fitting elongated hole  119  ( FIG. 10 ). The first fitting elongated hole  117  is fitted onto the rotation shaft  99  of the transport roller  75 . The second fitting elongated hole  119  is fitted onto a guide shaft  121  attached to the side wall portion  143  ( FIG. 9 ) of the sub-frame  141 . The advancing/retreating member  103  can repeatedly perform the above-described pushing and retreating within the length of these two elongated holes  117  and  119 . 
     Furthermore, a first shift pin  113  and a second shift pin  115  spaced apart from each other by a specified distance in the ejecting direction Y are provided on a surface of the advancing/retreating member  103  on the transport roller  75  side. The first shift pin  113  and the second shift pin  115  project toward the transport roller  75 . Out of the first shift pin  113  and the second shift pin  115 , the first shift pin  113  abuts the first cam member  101  so as to cause the advancing/retreating member  103  to move in the pushing direction with respect to the support member  53 . In contrast, the second shift pin  115  abuts the first cam member  101  so as to cause the advancing/retreating member  103  to move in the retreating direction. 
     Furthermore, referring to  FIG. 11 , a spring denoted by a reference sign  147  pulls the first shift pin  113  of the advancing/retreating member  103  toward the first cam member  101  so as to cause the first shift pin  113  to abut the first cam member  101 . 
     The Position Maintaining Mechanism: the Constant Force Spring 
     Next, based on  FIGS. 13 to 15 , the position maintaining mechanism  56  is described. As has been described, the position maintaining mechanism  56  includes the pulling mechanism  57  and the suppressing mechanism  58 . According to the present embodiment, the pulling mechanism  57  includes, for example, the constant force spring  57  formed by winding an elongated plate spring to have a spiral shape. 
     An unwound end  69  of the constant force spring  57  is fixed by a fixing screw (not illustrated) or the like to a portion of the base frame  37  near a position where the transport roller  75  is provided ( FIGS. 6 and 15 ). Accordingly, a force to move the support member  53  toward the upstream side in the ejecting direction Y is generated by utilizing a force of the constant force spring  57  for restoration of the original shape. 
     Furthermore, the suppressing mechanism  58  according to the present embodiment includes the regulating portion  58  that includes, for example, a wedge-shaped member regulating the rotation of the constant force spring  57  in the winding direction. Instead of the wedge-shaped member, another member that similarly acts such as a one-way roller can be used as the regulating portion  58 . 
     Furthermore, as illustrated in  FIG. 13 , the regulation release lever  60  that switches the state of the regulating portion  58  between a regulating state and a regulation release state is provided in the support member  53 . The regulation release lever  60  is connected to the regulating portion  58  at an end on the upstream side in the ejecting direction Y and provided with an operating portion  149  at an end on the downstream side in the ejecting direction Y. 
     In order to move the support member  53  positioned at the maximum stack position or at a midway in the stacking region  27  ( FIG. 15 ) of the stacker  21  toward a stack start position at an upstream end in the ejecting direction Y, the operating portion  149  of the regulation release lever  60  is pushed toward the upstream side in the ejecting direction Y so as to separate the regulating portion  58  from the wound portion of the constant force spring  57 . Thus, regulation performed by the regulating portion  58  is released. 
     In contrast, in order to set the regulating portion  58  in the regulating state again, a force to return the operating portion  149  toward the downstream side in the ejecting direction Y is applied by the spring  74  so as to cause the regulating portion  58  to abut the wound portion of the constant force spring  57  again. Thus, the regulating portion  58  is set to the regulating state. 
     Other than this, a retaining claw  71  projects downward on a lower surface of the slide block  61  that includes the winding mechanism  67  of the constant force spring  57 . The retaining claw  71  is retained in a slit-shaped retaining hole  73  ( FIGS. 6 and 15 ) formed at a central portion near a downstream end of the base frame  37  in the ejecting direction Y. Thus, the support member  53  can be kept at the maximum stack position where the support member  53  has receded rearward as much as possible. 
     Thus, in the stacker  21 , the support member  53  can be removably fixed to the base frame  37  when the support member  53  has been receded to the maximum stack position. 
     The Position Maintaining Mechanism: Frictional Resistance at a Sliding Surface 
     The receding mechanism  111  may apply, when the support member  53  is receding, a moving force G to move the support member  53  against a frictional force R due to frictional resistance with the stacking surface  22 , which is a sliding surface, and the position maintaining mechanism  56  may maintain the position of the support member  53  by utilizing the frictional resistance. That is, the support member  53  may stand still at its position due to the frictional resistance when the moving force G against the frictional force R is not applied. 
     With the above-described structure, the position of the support member  53  having been moved by the receding mechanism  111  can be maintained at the position by utilizing the frictional force of the sliding surface. Accordingly, the position maintaining mechanism  56  can be realized with a simple structure in which the constant force spring or the like is not used. 
     The Nip Release Mechanism 
     Next, based on  FIGS. 12A to 12D and 17A to 17D , the nip release mechanism  106  is described. 
     For example, the nip release mechanism  106  includes a second cam member  105 , a first shift lever  123 , and a second shift lever  127 . The second cam member  105  is made integral with the rotation shaft  99  of the transport roller  75 . The first shift lever  123  has one end  123   a  that abuts the second cam member  105 , another end  123   b  provided with a shaft  124 , and an intermediate portion  123   c  to which a spring  125  that pulls the intermediate portion  123   c  upward is attached. The second shift lever  127  has one end  127   a  ( FIG. 10 ) that abuts a lower surface of the intermediate portion  123   c  of the first shift lever  123  and another end  127   b  at which the second shift lever  127  is fixed to the pivot shaft  129  of the nipping member  107  with a fixing screw  128 . 
     The second cam member  105  pushes the one end  123   a  of the first shift lever  123  downward by a specified amount when the pushing of the advancing/retreating member  103  is performed. Furthermore, the one end  127   a  of the second shift lever  127  is pushed downward by a specified amount due to tilting of the first shift lever  123  about the tilting shaft  124 . 
     Thus, the pivot shaft  129  attached to the other end  127   b  of the second shift lever  127  pivots by a specified angle. This causes the nipping member  107  attached to the pivot shaft  129  with the fixing screw  130  to pivot in a direction separating from the transport roller  75 . Accordingly, the nipping roller  109  provided at the pivot free end of the nipping member  107  is separated from the transport roller  75 , thereby the nip is released. 
     The relationships between the advancing/retreating member  103 , the nipping member  107 , and the nip release mechanism  106  having been described are summarized as follows. 
     The stacker  21  according to the present embodiment includes a nipping member  107  that, together with the transport roller  75 , nips the medium P therebetween and transmits a transport force of the transport roller  75  to the medium P while nipping the medium P. When the advancing/retreating member  103  performs the pushing by which the support member  53  is caused to recede by the specified distance S ( FIGS. 12C and 17C ), the nipping between the transport roller  75  and the nipping roller  109  is released. 
     Furthermore, the nipping member  107  can be displaced between a position where the nipping member  107  together with the transport roller  75  forms a nip therebetween and a position where the nip between the nipping member  107  and the transport roller  75  is released. The second cam member  105  provided on the rotation shaft  99  of the transport roller  75  is moved in accordance with the rotation of the rotation shaft  99  of the transport roller  75 , thereby displacing the nipping member  107  between the nipping state and the nip release state. 
     With the nip release mechanism  106  that has the above-described structure and performs the above-described operations, the nipping member  107  is set in the nip release state while the advancing/retreating member  103  is pushing the surface of the support plate  59  of the support member  53  with the medium P pinched therebetween. Thus, the transport force of the transport roller  75  is reduced, thereby reducing jamming, creasing, and the like of the medium P. 
     Furthermore, a certain gap (for example, 1 to 10 mm) is formed between the transport roller  75  and the medium P supported by the support member  53 , so that the succeeding medium P being ejected is stacked along the front side of the medium P having been stacked and supported so as to be inclined as has been describe. This operation is realized by the above-described receding mechanism  111  and the position maintaining mechanism  56 . 
     4. Operating Form of the Processing Apparatus (see  FIGS. 4, 5, and 12A to 18B ) 
     Next, an operating form of the processing apparatus  1  according to the present embodiment is described by focusing on the operation of the stacker  21  according to the present embodiment with an example case where a plurality of the media P such as postcards or envelopes on which processes of recording addresses, text, or the like have been performed are stacked by using the stacker  21 . 
     In the following description, the operating form of the processing apparatus  1  is divided into four steps as follows: (A) mounting of the stacker; (B) preparation for stacking; (C) start of the stacking; and (D) end of the stacking and removal of the media. 
     A. Mounting of the Stacker (See  FIGS. 4 and 5 ) 
     First, the handle (not illustrated) provided in the front surface of the medium ejection tray  8  closing the ejection opening  20  formed in the side surface of the apparatus main body  2  is held by a hand so as to open the medium ejection tray  8  as illustrated in  FIG. 5 . In this state, the rear surface of the medium ejection tray  8  becomes the obverse side and the placement surface  23  is exposed. 
     Next, the stacker  21  is placed on the placement surface  23  and positioned by, for example, fitting projections (not illustrated) or the like formed on a lower surface of the base frame  37  of the stacker  21  into recesses (not illustrated) or the like formed in the placement surface  23 . 
     In so doing, the upstream side of the stacker  21  in the ejecting direction Y is inserted into the ejection opening  20  while being slightly inclined downward so as to perform the positioning with the projections or the like and the recesses or the like. After that, the downstream end side of the stacker  21  in the ejecting direction Y is moved downward so as to mount the stacker  21  on the placement surface  23  as illustrated in  FIG. 4 . 
     In this state, movements of the stacker  21  in the XY plane parallel to the placement surface  23  of the medium ejection tray  8  are regulated by the engagement of the projections or the like with the recesses or the like, and movements of the stacker  21  are also regulated in the vertical direction Z by abutment of an upper surface of the top plate portion of the support frame  137  having an inverted U shape provided in the space on the upstream side of the base frame  37  in the ejecting direction Y against a lower surface or the like of a top plate portion of the ejection opening  20 . 
     Furthermore, as illustrated in  FIG. 9 , when the stacker  21  is mounted on the placement surface  23  of the medium ejection tray  8 , the transmission rollers  79 L and  79 R, which are provided at the upstream end of the stacker  21  in the ejecting direction Y abut the ejection rollers  18 L and  18 R, which are provided in the ejection unit  10  of the processing apparatus  1 . This allows the motive power to be transmitted to the transport roller  75  of the stacker  21  via the power transmission unit  77 . Accordingly, high-speed stacking of the media P in the edge placement orientation (standing orientation) can be performed. 
     B. Preparation for Stacking (See  FIGS. 13 to 16 and 18B ) 
     Next, the handle portions  47  are held so as to adjust the distance between the left and right side guide portions  41 L and  41 R in accordance with the width of the media P to be stacked, and the fixing screws  45  are tightened so as fix the positions where the side guide portions  41 L and  41 R are attached. Next, when the support member  53  is fixed at the maximum stack position at the downstream end in the ejecting direction Y as illustrated in  FIG. 18A , the retaining claw  71  projecting from a lower end of the slide block  61  of the support member  53  is pulled out from the retaining hole  73  formed near the downstream end in the upper surface of the base frame  37  in the ejecting direction Y. Thus, the fixed state of the support member  53  is released. 
     Along with the releasing of the fixing, as illustrated in  FIG. 18B , the regulation release lever  60  provided in the support member  53  is pushed toward the upstream side in the ejecting direction Y so as to separate the regulating portion  58  from the wound portion of the constant force spring  57 . This releases the regulation of the movement of the support member  53  by the regulating portion  58  toward the upstream side in the ejecting direction Y. 
     As a result of the above-described operation, the force of the constant force spring  57  for restoration of the original shape acts on the support member  53 . Thus, the support member  53  can be moved to the stack start position at the upstream end in the ejecting direction Y while being guided by the projection  65  and the guide hole  63  ( FIG. 16 ). Then, after the support member  53  has been moved to the stack start position, a force to return to the downstream side in the ejecting direction Y is caused to act on the regulation release lever  60  (operating portion  149 ). Thus, the regulating portion  58  abuts the wound portion of the constant force spring  57  again. In this way, the movement of the support member  53  toward the upstream side in the ejecting direction Y is regulated. Here, the regulating portion  58  regulates the movement of the support member  53  toward the upstream side and does not regulate the movement of the support member  53  toward the downstream side in the ejecting direction Y. 
     C. Start of the Stacking (See  FIGS. 12A to 12D, 16 and 17A  to  17 D) 
     After the preparation for the stacking has been completed, specified processes of the processing apparatus  1  are performed on the medium P fed from the medium feed tray  7 . The medium P on which the processes have been performed is ejected to the outside of the apparatus main body  2  from the ejection unit  10 . 
     The ejection of the medium P is performed by rotating the ejection rollers  18 . The rotation of the ejection rollers  18  is transmitted to the transport roller  75  via the power transmission unit  77 , thereby the transport roller  75  is rotated in a direction in which the medium P is fed to the stacking region  27  of the stacker  21 . 
     The medium P ejected by the ejection rollers  18  is guided by the entrance guides  136  and moved to the stacker  21  side with side end portions thereof positioned in the gaps between the horizontal portions  135  of the left and right lifting-off suppressing members  133 L and  133 R and the upper surface of the base frame  37 . The medium P is transported in the face placement orientation (lying orientation) along the upper surface of the base frame  37  until a leading end thereof reaches a nipping point O ( FIGS. 15 and 16 ) between the transport roller  75  and the nipping member  107 . 
     When curl or the like occurs in the medium P being transported, lifting-off at the left and right side end portions of the medium P is suppressed by the horizontal portions  135  (first lifting-off suppressors) of the lifting-off suppressing members  133 . Lifting-off or bulging in the central portion of the medium P is suppressed by the suppressing plate  139  (second lifting-off suppressor;  FIG. 9 ) integral with the sub-frame  141 . 
     When the leading end of the medium P reaches the nipping point O, the medium P is nipped between the transport roller  75  and the nipping roller  109 . Thus, the feeding force of the transport roller  75  is transmitted to the leading end of the medium P. Then, the leading end of the medium P is caused to abut the surface of the support plate  59  of the support member  53  on the downstream side. 
     The leading end of the medium P abutting the surface of the support plate  59  is guided by the inclined surface of the support plate  59  without being changed and moved diagonally upward along the surface. 
     Then, when a trailing end of the medium P has passed through the nipping point O, the medium P no longer receives the feeding force from the transport roller  75 . Thus, a trailing end edge of the medium P is caused to abut the stacking surface  22  of the stacker  21 , and the medium P assumes the edge placement orientation (standing orientation) in which the back side of the medium P is supported by the support member  53 . Thus, stacking of a single medium P is completed. 
     At this time, the side end portions of the medium P in the width direction X are positioned in the gaps between the rear surfaces of the inclined portions  134  of the lifting-off suppressing members  133  and the front surface of the support plate  59 . Thus, lifting-off of the left and right side end portions of the medium P is suppressed by the inclined portions  134  (third lifting-off suppressor). Accordingly, transition of the orientation and transportation of the medium P are smoothly performed. 
     Furthermore, operations of the receding mechanism  111  and the nip release mechanism  106  are started in accordance with the rotation of the rotation shaft  99  of the transport roller  75 . Out of these, due to the rotation of the rotation shaft  99  of the transport roller  75 , the first cam member  101  is rotated so as to move the advancing/retreating member  103  in the receding mechanism  111  such that the advancing/retreating member  103  is pushed toward the support member  53  by the specified distance S. 
     This causes the support member  53  to recede by the specified distance S, thereby ensuring a space for stacking the medium P to be ejected next between the surface of the medium P having been stacked and the transport roller  75 . 
     Furthermore, at this time, the movement of the support member  53  toward the upstream side in the ejecting direction Y is regulated by the regulating portion  58  of the position maintaining mechanism  56 . Thus, the support member  53  is stopped at a position where the support member  53  has receded by the specified distance S without being changed and ready for stacking of the next medium P. 
     Furthermore, the nip release mechanism  106  also performs a specified operation in synchronization with the operation of the receding mechanism  111 . That is, due to the rotation of the rotation shaft  99  of the transport roller  75 , the second cam member  105  is rotated so as to push downward the one end  123   a  of the first shift lever  123 . Thus, the first shift lever  123  is tilted downward against a force of the spring  125  directed upward. 
     The downward tilting of the first shift lever  123  pushes downward the one end  127   a  of the second shift lever  127  and causes the pivot shaft  129  attached to the other end  127   b  to pivot in a direction in which the pivot free end of the nipping member  107  is pushed downward. 
     This operation moves the nipping roller  109  from a nip position where the nipping roller  109  contacts a circumferential surface of the transport roller  75  to a nip release position where the nipping roller  109  is kept separated from the circumferential surface of the transport roller  75 . Thus, transmission of the feeding force to the medium P is stopped. 
     Thus, the feeding force transmitted from the transport roller  75  is reduced by releasing the nipping state between the transport roller  75  and the nipping member  107  when the receding mechanism  111  causes the advancing/retreating member  103  to perform the pushing. This suppresses the occurrence of creasing or the like in the medium P. 
     Next, based on  FIGS. 12A to 12D and 17A to 17D , the relationship between the position of the advancing/retreating member  103  and the nipping state or the nip release state between the transport roller  75  and the nipping member  107  is described. As illustrated in  FIGS. 12A and 17A , immediately after the leading end of the medium P has reached the nipping point O, the medium P is subjected to a large feeding force from the transport roller  75  and the nipping member  107  in the nipping state, and transportation of the medium P starts. 
     At this time, the advancing/retreating member  103  is disposed at a retreated position where the advancing/retreating member  103  has been retreated to the upstream side in the ejecting direction Y, and the nipping member  107  is in the nipping state in which the nipping roller  109  abuts the circumferential surface of the transport roller  75  with the medium P nipped therebetween. 
     When the rotation shaft  99  of the transport roller  75  continues rotating and the stacker  21  enters a state illustrated in  FIGS. 12B and 17B , the advancing/retreating member  103  is gradually advancing in the pushing direction. Furthermore, the nipping member  107  starts pivoting downward about the pivot shaft  129 . Thus, a nipping force of the transport roller  75  and the nipping member  107  acting on the medium P is reduced, and accordingly, the feeding force acting on the medium P is reduced. 
     Furthermore, the rotation shaft  99  of the transport roller  75  continues rotating and the stacker  21  enters a state illustrated in  FIGS. 12C and 17C , the advancing/retreating member  103  is moved to a pushing position on the downstream side in the ejecting direction Y. Thus, the support member  53  is pushed in so as to recede by the specified distance S. At this time, the nipping member  107  pivots further so as to enter the nip release state in which the nipping roller  109  is kept separated from the circumferential surface of the transport roller  75 . 
     Furthermore, when the rotation shaft  99  of the transport roller  75  continues rotating and the stacker  21  enters a state illustrated in  FIGS. 12D and 17D , the advancing/retreating member  103  is gradually being retreated toward the above-described “position”. The nipping member  107  starts pivoting upward about the pivot shaft  129 . Thus, the nipping force of the transport roller  75  and the nipping member  107  acting on the medium P is gradually increased, and accordingly, the feeding force acting on the medium P is increased. 
     Then, when the rotation shaft  99  of the transport roller  75  continues rotating further, the state of the stacker  21  returns to the state illustrated in  FIGS. 12A and 17A . After this, as the similar operations are being repeatedly performed, the media P are sequentially stacked one after another in the stacking region  27  of the stacker  21 , and the support member  53  recedes on a specified-distance-S by specified-distance-S basis. 
     D. End of the Stacking and Removal of the Media (See  FIGS. 15 and 18A to 18B ) 
     When all the media P have been processed, a single medium P that is the last one of the media P is ejected to the outside of the apparatus main body  2  by the ejection rollers  18  through the ejection opening  20 . The medium P ejected by the ejection rollers  18  is transported toward the stacking region  27  through the transport operation performed by the transport roller  75  and the nipping member  107 . Thus, stacking of all the media P is completed. 
     After the stacking of all the media P has been completed, the support member  53  is moved to the maximum stack position at the downstream end in the ejecting direction Y, and the retaining claw  71  projecting from the lower end of the slide block  61  of the support member  53  is retained in the retaining hole  73  formed in the base frame  37 . Thus, the support member  53  is fixed at the maximum stack position. This increases ease of removal of the media P stacked in the stacking region  27 , and combined with the fact that the height of the guide side plates  55 L and  55 R of the side guide portions  41 L and  41 R is reduced on the downstream side in the ejecting direction Y, the media P is smoothly removed. 
     With the stacker  21  and the processing apparatus  1  according to the present embodiment having the above-described structures, the media P stacked in the stacker  21  assume such an edge placement orientation (standing orientation) in which the media P are inclined with the upper portion thereof being further in the ejecting direction Y than the lower portion thereof. Accordingly, compared to the related-art processing apparatus that does not use the stacker  21  and stacks the media P in the face placement orientation (lying orientation) on the placement surface  23  of the medium ejection tray  8 , the number of the media P to be stacked can be significantly increased. 
     Furthermore, with the receding mechanism  111  and the position maintaining mechanism  56 , the position of the support member  53  can gradually recede in accordance with the progress of stacking of the media P and kept instead of being constantly fixed at the maximum stack position. Thus, the need of a conveyer belt or the like that transports the media P to the maximum stack position is dropped, and accordingly, the techniques herein can contribute to reduction in size, weight, and cost of the apparatus. Thus, it is possible to provide the stacker  21  that has a large stacking capacity so as to be usable with a high-speed processing apparatus performing specified processes at high speed and that is capable of continuous stacking, and it is also possible to provide the processing apparatus  1  that includes the stacker  21 . 
     Other Embodiments 
     Although the stacker  21  and the processing apparatus  1  according to the disclosure basically have the structures having been described, of course, it is possible to change or omit partial structures without departing from the gist of the disclosure. 
     For example, use of the processing apparatus  1  according to the disclosure is not limited to an ink jet printer. The processing apparatus  1  according to the disclosure can be used for another recording apparatus, copier, or the like such as a laser printer. In addition, the processing apparatus  1  according to the disclosure can be used for any of a variety of other processing apparatuses that perform certain processes on a large amount of the media P at high speed. 
     Furthermore, instead of the constant force spring  57  used as the pulling mechanism  57 , another type of spring of a different method such as a plate spring, coil spring, and a pneumatic spring can be used as the pulling mechanism  57 . Furthermore, the power transmission unit  77  does not necessarily have a structure in which the motive power is obtained through pressure contact of the transmission rollers  79  with the ejection rollers  18 . The motive power may be obtained from gears, pulleys, or the like for outputting provided on the shaft  25  of the ejection rollers  18 . 
     Furthermore, the media P to be stacked in the stacker  21  are not limited to postcards or envelopes in a portrait format. The media P to be stacked may be postcards or envelopes in a landscape format. Furthermore, the media P may be media P of another type such as business cards or another media having no definite form. Furthermore, it is possible to provide, in the medium ejection tray  8 , a sensor that detects whether the stacker  21  is disposed on the placement surface  23  of the medium ejection tray  8 . In addition, instead of utilizing the rotation of the existing ejection rollers  18  on the processing apparatus  1  side as the motive power for the transport roller  75 , the receding mechanism  111 , and the nip release mechanism  106 , rotation of a motor that is independently provided in the stacker  21  can be utilized to operate the transport roller  75 , the receding mechanism  111 , and the nip release mechanism  106 .