Patent Publication Number: US-9427982-B2

Title: Recording apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a recording apparatus that is represented by a facsimile, a printer or the like. 
     2. Related Art 
     In a recording apparatus that is represented by a facsimile, a printer or the like, there is also the recording apparatus that can perform recording on both surfaces of recording paper as an example of a medium. For example, as illustrated in JP-A-2012-240813, the recording apparatus has an inverted path in which the recording paper is inverted. The recording apparatus performs recording on a first surface (a front surface) of the recording paper, feeds the recording paper backward to the inverted path, and transports the recording paper again to a region that faces a recording head while a second surface (a back surface) thereof faces upward. 
     In the recording apparatus according to JP-A-2012-240813, an outer circumferential surface of one roller (hereinafter, referred to as “inversion roller”) is used to form the inverted path. Accordingly, in this configuration, there is a problem in that when the apparatus is designed on the basis that paper of a large size is used, it is necessary to make the inversion roller large, and the size of the apparatus becomes large. 
     In contrast, the apparatus may also have a configuration in which the inverted path is not formed by the outer circumferential surface of the inversion roller but by a guide member, and transportation rollers are disposed at multiple locations. However, in this case, there is a problem in that the number of the disposed transportation rollers is likely to increase, and the number of components increases. 
     A printing apparatus according to JP-A-2012-118142 adopts a configuration in which a printing path for duplex printing is disposed on a lower side of a printing mechanism, printed paper is fed to the lower side of the printing mechanism, and is returned to a printing region again. However, in this configuration, there is a problem in that a dimension in a height direction of the apparatus becomes large. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a recording apparatus that can ensure the length of an inverted path to perform recording on both surfaces of a medium while suppressing the dimension of the apparatus. 
     A recording apparatus according to an aspect of the invention includes a recording head that performs recording on a medium; a first roller that inverts the medium which is fed from a side of the recording head by using an outer circumferential surface thereof; and a second roller of which an outer circumferential surface is in contact with medium transportation paths before and after the medium is inverted by the first roller and which exerts a transportation force on the medium. 
     According the aspect, since an inverted path for inverting the medium includes the first roller that inverts the medium by using the outer circumferential surface thereof, and the second roller of which the outer circumferential surface is in contact with the medium transportation paths before and after the medium is inverted by the first roller and which exerts the transportation force on the medium, the diameter of the first roller may be prevented from becoming large, and it may be ensured that the inverted path has the length enough for the second roller to invert the medium. 
     Since the second roller is in contact with the medium transportation paths before and after the medium is inverted by the first roller and which exerts the transportation force on the medium, one roller (the second roller) contributes to formation of the medium transportation paths before and after the medium is inverted by the first roller and thus, the number of the rollers that are disposed may be reduced, and an increase in cost may be suppressed. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may be provided at the same position in a height direction of the apparatus. 
     According to the aspect, since the first and the second rollers are provided at the same position in the height direction of the apparatus, dimensions of disposition regions of the first and the second rollers may be limited to the minimum in the height direction of the apparatus. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may be provided at the same position as a position of a disposition region of the recording head in the height direction of the apparatus. 
     According to the aspect, since the first and the second rollers are provided at the same position as the position of the disposition region of the recording head in the height direction of the apparatus, the disposition region of the recording head may be prevented from overlapping the disposition regions of the first and the second rollers in the height direction of the apparatus. The increase of the dimension in the height direction of the apparatus may be suppressed. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may have the same diameter. 
     According to the aspect, since the first and the second rollers have the same diameter, the first and the second rollers may be made of a common configuration member, and low costs may be achieved. Circumferential velocities of the outer circumferences of the rollers, that is, medium transportation velocities may be equal to each other when the numbers of rotations of both rollers are set to be the same. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may have the same medium transportation velocity. 
     According to the aspect, since the first and the second rollers have the same medium transportation velocity, tension or deflection is not exerted on the medium between the first and the second rollers. As a result, the medium may be reliably transported. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may be driven by a common driving source. 
     According to the aspect, since the first and the second rollers are driven by a common driving source, an increase in costs of driving means of the first and the second rollers may be suppressed. 
     In the recording apparatus according to the aspect of the invention, a plurality of the second rollers may be provided in a medium width direction that intersects with a medium transportation direction. 
     According to the aspect, since the plurality of second rollers are provided in the medium width direction that intersects with the medium transportation direction, the medium is in contact with the second roller at multiple positions in the width direction of the medium and thus, oblique feeding of the medium may be suppressed during the transportation thereof. 
     In the recording apparatus according to the aspect of the invention, the first and the second rollers may be provided with a plurality of driven rollers along the medium transportation path before the inversion of the medium and the medium transportation path after the inversion of the medium. 
     According to the aspect, since the first and the second rollers are provided with the plurality of driven rollers along the medium transportation paths, the medium can be smoothly transported. 
     The recording apparatus according to the aspect of the invention may further include a first driven roller that is rotationally driven while the medium is nipped between the second roller and the first driven roller; and a second driven roller that is provided on an upstream side of the first driven roller in the medium transportation direction, and is rotationally driven while the medium is nipped between the second roller and the second driven roller. 
     According to the aspect, since the medium is nipped by the plurality of driven rollers (the first driven roller and the second driven roller) of the second roller, oblique feeding of the medium may be reliably suppressed during the transportation thereof. 
     The recording apparatus according to the aspect of the invention may further include a third driven roller that is rotationally driven while the medium is nipped between the first roller and the third driven roller. 
     According to the aspect, since the recording apparatus further includes the third driven roller that is rotationally driven while the medium is nipped between the first roller and the third driven roller, the plurality of driven rollers, that is, the first to the third driven rollers can reliably suppress oblique feeding of the medium during the transportation thereof. 
     In the recording apparatus according to the aspect of the invention, the first driven roller may be positioned above a center shaft of the second roller in the height direction of the apparatus, and on a front side of the apparatus in a front and back direction of the apparatus. 
     According to the aspect, the medium may be sent from the second roller toward the recording head in a natural posture and without difficulty. 
     The recording apparatus according to the aspect of the invention may further include a fourth driven roller that is rotationally driven while the medium fed from the recording head toward the first roller is nipped between the second roller and the fourth driven roller. 
     According to the aspect, since the fourth driven roller transports the medium fed from the recording head toward the first roller to the first roller while the medium is nipped between the second roller and the fourth driven roller, the medium may be smoothly inverted in the first roller. 
     The recording apparatus according to the aspect of the invention may further include a medium container that can contain a plurality of the mediums. A feeding path of the medium fed from the medium container converges with the medium transportation path formed by the first roller. 
     According to the aspect, since the feeding path of the medium, which is fed from the medium container that can contain the plurality of mediums, converges with the medium transportation path formed by the first roller, that is, the first roller forms not only the inverted path but also the non-inverted path, space saving may be achieved and the number of components may be reduced. 
     The recording apparatus according to the aspect of the invention may further include a medium support tray that supports the medium that is not yet fed. A supply path of the medium supplied via the medium support tray converges with the medium transportation path formed by the first roller. 
     According to the aspect, since the recording apparatus includes the medium support tray that supports the medium that is not yet fed, and the supply path of the medium supplied via the medium support tray converges with the medium transportation path formed by the first roller, that is, the first roller also forms the supply path of the medium from the medium support tray, space saving may be achieved and the number of components may be reduced. 
     In addition, since the second roller is positioned downstream of the first roller, the length (the length of a path of up to a recording region) of the supply path of the medium supplied via the medium support tray may be ensured. Accordingly, the following operation effect is obtained as an example. For example, when a user manually supplies the medium via the medium support tray, there is a problem in that the user inserts the medium into the apparatus deep enough to significantly exceed a recommended setting position. At this time, if a leading edge of the medium reaches a position that faces the recording head, the recording head cannot properly perform recording on the medium. However, as described above, since the length of the supply path of the medium supplied via the medium support tray may be ensured, the problem may be prevented from occurring. 
     In the recording apparatus according to the aspect of the invention, a unit body that is attachable and detachable with respect to a recording apparatus main body is configured to have the first and the second rollers. 
     According to the aspect, since the unit body that is attachable and detachable with respect to the recording apparatus main body is configured to have the first and the second rollers, when the unit body is detached from the recording apparatus main body, the inverted path of the medium is exposed. Accordingly, when the medium is jammed (when a paper jam occurs), the jammed medium may be easily removed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a perspective view of a printer according to the invention. 
         FIG. 2  is a rear perspective view of the printer according to the invention. 
         FIG. 3  is a cross-sectional side view illustrating a paper transportation path of the printer according to the invention. 
         FIG. 4  is a cross-sectional side view illustrating a state where a transportation unit is detached from the paper transportation path of the printer according to the invention. 
         FIG. 5  is an enlarged view illustrating the vicinity of the transportation section in the paper transportation path of the printer according to the invention. 
         FIG. 6  is a perspective view of the transportation unit according to the invention. 
         FIG. 7A  is a perspective view illustrating a state where the paper transportation path in the transportation unit is open. 
         FIG. 7B  is a perspective view when the transportation unit is seen from below. 
         FIG. 8  is a rear perspective view illustrating a state where a back surface cover of the printer according to the invention is open. 
         FIG. 9A  is a perspective view when the printer according to the invention is seen from above in a state where the back surface cover is open. 
         FIG. 9B  is an enlarged view of the back surface cover in  FIG. 9A . 
         FIG. 10A  is a rear perspective view illustrating a state where the transportation unit is detached from the printer. 
         FIG. 10B  is an enlarged perspective view illustrating a stopper section provided on the printer. 
         FIG. 11A  is a view illustrating a power transmission path of the transportation unit according to the invention. 
         FIG. 11B  is an enlarged view of the transportation unit in  FIG. 11A . 
         FIG. 12A  is a cross-sectional side view illustrating a state where the back surface cover of the printer according to the invention is open. 
         FIG. 12B  is a cross-sectional side view illustrating a state where power transmission in the power transmission path of the transportation unit is disconnected. 
         FIG. 13A  is a cross-sectional side view illustrating states of the transportation unit and the stopper section of the printer in  FIG. 12B . 
         FIG. 13B  is a cross-sectional side view illustrating a state where the transportation unit is detached from the printer. 
         FIG. 14  is a cross-sectional side view of a printer to which a transportation unit of a second embodiment is attached. 
         FIG. 15  is a cross-sectional side view of the printer from which the transportation unit of the second embodiment is detached. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. In each of the embodiments, the same reference signs will be assigned to the same configurations. The configurations will be described only in a first embodiment, and will not be described in another embodiment. 
       FIG. 1  is a perspective view of a printer according to the invention.  FIG. 2  is a rear perspective view of the printer according to the invention.  FIG. 3  is a cross-sectional side view illustrating a paper transportation path of the printer according to the invention.  FIG. 4  is a cross-sectional side view illustrating a state where a transportation unit is detached from the paper transportation path of the printer according to the invention.  FIG. 5  is an enlarged view illustrating the vicinity of the transportation section in the paper transportation path of the printer according to the invention.  FIG. 6  is a perspective view of the transportation unit according to the invention.  FIG. 7A  is a perspective view illustrating a state where the paper transportation path in the transportation unit is open.  FIG. 7B  is a perspective view when the transportation unit is seen from below. 
       FIG. 8  is a rear perspective view illustrating a state where a back surface cover of the printer according to the invention is open.  FIG. 9A  is a perspective view when the printer according to the invention is seen from above in a state where the back surface cover is open.  FIG. 9B  is an enlarged view of the back surface cover in  FIG. 9A .  FIG. 10A  is a rear perspective view illustrating a state where the transportation unit is detached from the printer.  FIG. 10B  is an enlarged perspective view illustrating a stopper section provided on the printer.  FIG. 11A  is a view illustrating a power transmission path of the transportation unit according to the invention.  FIG. 11B  is an enlarged view of the transportation unit in  FIG. 11A . 
       FIG. 12A  is a cross-sectional side view illustrating a state where the back surface cover of the printer according to the invention is open.  FIG. 12B  is a cross-sectional side view illustrating a state where power transmission in the power transmission path of the transportation unit is disconnected.  FIG. 13A  is a cross-sectional side view illustrating states of the transportation unit and the stopper section of the printer in  FIG. 12B .  FIG. 13B  is a cross-sectional side view illustrating a state where the transportation unit is detached from the printer.  FIG. 14  is a cross-sectional side view of a printer to which a transportation unit of a second embodiment is attached.  FIG. 15  is a cross-sectional side view of the printer from which the transportation unit of the second embodiment is detached. 
     In  FIGS. 3 and 4 , substantially all rollers are drawn on the same drawing sheet to illustrate the rollers disposed in the paper transportation path of a printer  10 . However, the rollers are not always coincidentally positioned in a depth direction (in a front and back direction of a drawing sheet in a  FIG. 3 ) of the printer  10  (some rollers are coincidentally positioned in the depth direction thereof). In an X, Y and Z coordinate system of each drawing, an X direction indicates a scanning direction of a recording head, a Y direction indicates a depth direction of a recording apparatus, and a Z direction indicates a height direction of the printer. In each drawing, a −Y direction indicates a front surface side of the apparatus, and a +Y direction indicates a back surface side thereof. 
     Outline of Printer 
       FIGS. 1 and 2  illustrate the printer  10  according to the invention. The printer  10  includes an apparatus main body  12 , and a manuscript scanning apparatus  14  that is provided on an upper portion of the apparatus main body  12  to be rotationally movable with respect to the apparatus main body  12 . The apparatus main body  12  includes an operation panel section  16  which is provided on the front surface side (on a side of the −Y direction in  FIG. 1 ) of the apparatus, and through which a user operates the printer  10 ; a discharge port  18  that is open toward the front surface side of the apparatus; and medium containers  20  that are disposed under the discharge port  18 . 
     The apparatus main body  12  includes a back surface cover  22  on the back surface side (on a side of the +Y direction in  FIG. 2 ) of the apparatus as an opening/closing body that is configured to be rotationally movable with respect to the apparatus main body  12 . In  FIG. 2 , the back surface cover  22  is closed with respect to the apparatus main body  12 . The back surface cover  22  includes a medium support tray  24  that is rotationally movable with respect to the back surface cover  22  and is connected to a side opposite to a rotationally moving shaft thereof to be described later, that is, a free end side of the back surface cover  22 . 
     Subsequently, in the printer  10 , a transportation path of paper P as a “medium” will be described with reference to  FIGS. 3 and 5 . The printer  10  includes a medium container  20 , a transportation section  26 , a recording section  28  and a discharge section  30  in the apparatus main body  12 . 
     The medium container  20  includes an upper stage tray  32  that is positioned on an upper side in the Z direction, and a lower stage tray  34  that is positioned below the upper stage tray  32 . The upper stage tray  32  and the lower stage tray  34  are configured in such a manner that the upper stage tray  32  and the lower stage tray  34  can be mounted onto and detached from the apparatus main body  12  from a front side (the −Y direction in  FIG. 3 ) of the apparatus. 
     Each of the upper stage tray  32  and the lower stage tray  34  contains a plurality of the paper P. In the embodiment, each of the upper stage tray  32  and the lower stage tray  34  contains a different type of paper, but in a case where it is not particularly necessary to distinguish the types of the paper from each other, the paper is referred to as the “paper P”. The paper P is an example of the medium. 
     Pickup rollers  36  and  38  that are rotationally driven by driving sources which are not illustrated are respectively provided above the upper stage tray  32  and the lower stage tray  34 . The pickup rollers  36  and  38  are respectively provided on rocking members  44  and  46  that respectively rock about rocking shafts  40  and  42 . 
     When the paper P contained in the upper stage tray  32  is fed to a downstream side of the transportation path based on an instruction input from the operation panel section  16 , a PC or the like, the pickup roller  36  rotates in contact with the uppermost paper P contained in the upper stage tray  32  and thus, the uppermost paper P is fed from the upper stage tray  32  to the downstream side of the transportation path. Similarly, when the paper P contained in the lower stage tray  34  is fed to the downstream side of the transportation path, the pickup roller  38  rotates in contact with the uppermost paper P contained in the lower stage tray  34  and thus, the uppermost paper P is fed from the lower stage tray  34  to the downstream side of the transportation path. 
     When the back surface cover  22  is closed with respect to the apparatus main body  12 , an inner surface of the back surface cover  22  forms a part of the transportation path of the paper P. That is, a feeding path section  48  formed on an inside of the back surface cover  22  guides the paper P fed from the upper stage tray  32  and the lower stage tray  34  to the transportation section  26 . 
     The transportation section  26  includes a first roller  50 ; a second roller  52 ; a first transportation driven roller  54  as a “first driven roller”; a second transportation driven roller  56  as a “second driven roller”; a third transportation driven roller  58  as a “third driven roller”; a fourth transportation driven roller  60 ; a fifth transportation driven roller  62 ; and a pair of transportation rollers  64 . 
     Herein, a transportation unit  66  (refer to  FIGS. 3, 4 and 6 ) that is attachable and detachable with respect to the apparatus main body  12  is configured to have the first roller  50 , the second roller  52 , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58 . The transportation unit  66  as a “unit body” will be described later. In the embodiment, the first roller  50  and the second roller  52  are driven to rotate by a common drive motor  116  to be described later. 
     The transportation section  26  will be described later. The paper P is transported to the transportation rollers  64  via the fifth transportation driven roller  62  and the third transportation driven roller  58  which are in contact with the first roller  50  along the transportation path in the transportation section  26 , and via the second transportation driven roller  56  and the first transportation driven roller  54  which are in contact with the second roller  52  along the transportation path in the transportation section  26 . The recording section  28  is provided in the transportation path on a downstream side of the transportation rollers  64  of the transportation section  26 . 
     The recording section  28  is provided in the transportation path on the downstream side of the transportation rollers  64  of the transportation section  26 . The recording section  28  includes a carriage  68  that can move in the scanning direction (in the X axis direction in  FIG. 3 ), a recording head  70  that is provided on a lower portion of the carriage  68  to eject ink on the paper P, and a platen  72  that is provided to face the recording head  70  and support the paper P. 
     The discharge section  30  is provided in the transportation path on the downstream side of the recording section  28 . The discharge section  30  is provided with a pair of discharge rollers  74 , and a discharge stacker  76  on which the paper P discharged from the discharge roller  74  is mounted and is provided on the front side (in the −Y direction) of the apparatus to protrude from the discharge port  18 . When the paper P is fed from the transportation section  26  to the recording section  28  along the transportation path, recording is performed on a first surface of the paper P. After the recording is completed, the paper P is nipped by the discharge roller  74 , and is discharged to the discharge stacker  76  that is provided on the front side of the apparatus. 
     When the recording section  28  performs recording on both surfaces of the paper P in the printer  10 , the recording section  28  performs the recording on the first surface of the paper P, and then while a trailing edge of the paper when the recording is performed on the first surface becomes a leading edge thereof due to a backward feeding operation of the transportation rollers  64  and the discharge rollers  74 , the paper P is fed to an inverted path  78  to be described later, which is positioned on a side further in a −Z direction than the second roller  52  in the Z axis direction, that is, which is positioned below the transportation unit  66 . The inverted path  78  is provided below the first roller  50  and the second roller  52 , that is, along the −Z direction in  FIG. 3  and is provided to converge with the transportation path of the paper P from the medium container  20 . 
     For this reason, the paper P is fed to the recording section  28  again via the transportation path from the inverted path  78  and a transportation path that is positioned above the first roller  50  and the second roller  52 , and the recording section  28  performs recording on a second surface. After the recording is completed, the paper P is nipped by the discharge rollers  74 , and is discharged to the discharge stacker  76  that is provided on the front side of the apparatus. 
     First Embodiment 
     Configuration of Transportation Section 
     Subsequently, the transportation section  26  will be described with reference to  FIGS. 3 and 5 . In  FIG. 5 , a solid line indicates the transportation path of the medium fed from the medium container  20 , and a broken line indicates the inverted path of the paper P. The first roller  50  and the second roller  52  are provided at the same position in the Z axis direction in  FIG. 3 . For this reason, it is possible to limit dimensions of disposition regions of the first roller  50  and the second roller  52  to the minimum in the Z axis direction. 
     The first roller  50  and the second roller  52  are disposed with a gap in the Y axis direction therebetween. That is, in the transportation path of the paper P, the first roller  50  is positioned on an upstream side of the transportation path, and the second roller  52  is positioned on the downstream side of the transportation path. The gap is set to have a length less than the minimum length in a transportation path direction of the paper P corresponding to the printer  10 . 
     Furthermore, in the front and back direction of the apparatus (in the Y axis direction in  FIGS. 3 and 5 ) with respect to the recording head  70  to be described later of the recording section  28 , the first roller  50  and the second roller  52  are positioned on a back side (in the +Y direction) with respect to the disposition region of the recording head  70 , and are provided at the same position as a position of the disposition region of the recording head  70  in the height direction of the apparatus (in the Z axis direction). For this reason, it is possible to prevent the disposition region of the recording head  70  from overlapping the disposition regions of the first roller  50  and the second roller  52  in the height direction (in the Z axis direction) of the apparatus, and it is possible to suppress increase of the dimension in the height direction (in the Z axis direction) of the apparatus. 
     As illustrated in  FIG. 5 , the first roller  50  inverts the paper P fed from a side of the recording head  70  by using an outer circumferential surface thereof and thus, the first surface is on the bottom, and the second surface is on the top. Furthermore, an outer circumferential surface of the second roller  52  is in contact with the transportation path before the paper P is inverted by the first roller  50 , that is, the inverted path  78 , and is in contact with the transportation path after the paper P is inverted by the first roller  50 , that is, the transportation path above the first and the second rollers  50  and  52  and thus, the second roller  52  exerts a transportation force on the paper P. 
     In  FIG. 3 , the first transportation driven roller  54  is positioned above a center shaft of the second roller  52  and on the front side of the apparatus, that is, on the side of the −Y direction, and is in contact with the second roller  52 . That is, while the paper P is nipped between the second roller  52  and the first transportation driven roller  54 , the first transportation driven roller  54  is rotationally driven to transport the paper P. The second transportation driven roller  56  is positioned on an upstream side in the transportation path of the first transportation driven roller  54 , and on the side further in the +Z direction than the second roller  52  in the Z axis direction in  FIG. 3 . The second transportation driven roller  56  is in contact with the second roller  52 . That is, while the paper P is nipped between the second roller  52  and the second transportation driven roller  56 , the second transportation driven roller  56  is rotationally driven to transport the paper P to the first transportation driven roller  54 . 
     For this reason, when the second roller  52  transports the paper P along the transportation path, the first transportation driven roller  54  and the second transportation driven roller  56  transport the paper P while nipping the paper P and thus, it is possible to reliably suppress oblique feeding of the paper P during the transportation. Furthermore, it is possible to send the paper P from the second roller  52  toward the recording head  70  in a natural posture and without difficulty. 
     The third transportation driven roller  58  is positioned on the upstream side in the transportation path of the second transportation driven roller  56 , and the third transportation driven roller  58  is positioned on the side further in the +Z direction than the first roller  50  in the Z axis direction in  FIG. 3 , and is in contact with the first roller  50 . That is, while the paper P is nipped between the first roller  50  and the third transportation driven roller  58 , the third transportation driven roller  58  is rotationally driven to transport the paper P toward the second roller  52 . 
     The pair of transportation rollers  64  is provided on a downstream side of the transportation path from a nipping position between the second roller  52  and the first transportation driven roller  54 . While the paper P is nipped between the first roller  50  and the third transportation driven roller  58 , and then between the second roller  52  and the second transportation driven roller  56 , and then between the second roller  52  and the first transportation driven roller  54 , that is, while the paper P is nipped in the sequence listed along the transportation path, the paper P is transported to the transportation rollers  64 . 
     For this reason, when the paper P is transported by the first roller  50  and the second roller  52  along the transportation path, the paper P is transported while being nipped by the third transportation driven roller  58 , and then by the second transportation driven roller  56  and then by the first transportation driven roller  54  in the sequence listed and thus, it is possible to reliably suppress oblique feeding of the paper P during the transportation. 
     In the transportation path, the length of the path from the nipping position between the second roller  52  and the first transportation driven roller  54  to a nipping position between the pair of transportation rollers  64  is set to be less than the minimum length in the transportation path direction of the paper P corresponding to the printer  10 . 
     In the inverted path illustrated by the broken line in  FIG. 5 , the length of the inverted path is set to be greater than the maximum length in the transportation path direction of the paper P corresponding to the printer  10 , in such a manner that leading edge and trailing edge sides in the transportation direction of the paper P do not overlap with each other in an inverted transportation path thereof. 
     For this reason, it is possible to prevent the diameter of the first roller  50  from becoming large, and to ensure that the inverted path  78  has sufficient length for the second roller  52  to invert the paper P. Since the second roller  52  can exert a transportation force on the inverted path before the paper P is inverted and on the transportation path after the paper P is inverted, it is possible to reduce the number of the rollers that are disposed, and to suppress an increase in cost. 
     The fourth transportation driven roller  60  is positioned on the side further in the −Z direction than the second roller  52  in the Z axis direction in  FIG. 3 , and is in contact with the second roller  52 . Furthermore, the fifth transportation driven roller  62  is positioned on an upper stream side in the transportation path of the third transportation driven roller  58 , and is provided on the feeding path section  48  of the back surface cover  22  forming a part of the transportation path from the medium container  20  to be in contact with the first roller  50 . That is, while the paper P is nipped between the first roller  50  and the fifth transportation driven roller  62 , the fifth transportation driven roller  62  is rotationally driven to transport the paper P toward the third transportation driven roller  58 . When the back surface cover  22  to be described later is open with respect to the apparatus main body  12 , the fifth transportation driven roller  62  separates from the first roller  50 . 
     Herein, the transportation path of the paper P will be described again. The paper P fed from the upper stage tray  32  and the lower stage tray  34  is guided to the feeding path section  48  of the back surface cover  22 , and is nipped by the first roller  50  and the fifth transportation driven roller  62 . The paper P is fed along the outer circumferential surface of the first roller  50 , and is nipped by the first roller  50  and the third transportation driven roller  58 . The paper P is fed to the downstream side of the transportation path. 
     That is, the feeding path of the paper P fed from the medium container  20  (the upper stage tray  32  and the lower stage tray  34 ) converges with the transportation path formed by the first roller  50 . For this reason, the first roller  50  forms not only the inverted path but also the non-inverted path. Accordingly, it is possible to achieve space saving and to reduce the number of components. 
     The paper P supported by the medium support tray  24  is drawn into the transportation path from a section between the fifth transportation driven roller  62  and the third transportation driven roller  58  in the transportation path via the medium support tray  24  and the feeding path section  80 , and the leading edge of the paper P is nipped by the first roller  50  and the third transportation driven roller  58 . The paper P fed from the medium support tray  24  converges with the transportation path of the paper P transported from the medium container  20  and is fed to the downstream side of the transportation path. 
     That is, a supply path of the paper P supplied from the medium support tray  24  converges with the transportation path formed by the first roller  50 . For this reason, the first roller  50  can form the supply path of the medium from the medium support tray  24 . Accordingly, it is possible to achieve space saving and to reduce the number of components. 
     As illustrated in  FIG. 5 , since the second roller  52  is positioned downstream of the first roller  50 , it is possible to ensure the length (the length of the path of up to the recording section  28 ) of the supply path of the paper P supplied via the medium support tray  24 . Accordingly, when a user manually supplies the paper P via the medium support tray  24 , there is a problem in that the user inserts the paper P into the apparatus deep enough to significantly exceeding a recommended setting position. At this time, if the leading edge of the paper P reaches a position that faces the recording head  70 , the recording head  70  cannot properly perform recording on the paper P. However, since it is possible to ensure the length of the supply path of the paper P supplied via the medium support tray  24 , it is possible to prevent the problem from occurring. 
     Subsequently, the paper P is nipped by the second roller  52  and the second transportation driven roller  56 . The paper P is fed to the downstream side of the transportation path, and is nipped by the second roller  52  and the first transportation driven roller  54 . Thereafter, the paper P is further transported to the pair of transportation rollers  64 . The paper P is nipped by the transportation rollers  64 , and is fed to the recording section  28  on the downstream side of the transportation path, and recording is performed on the first surface of the paper P. After the recording is completed, the paper P is nipped by the discharge rollers  74 , and is discharged to the discharge stacker  76  that is provided on the front side of the apparatus. 
     When the recording section  28  performs recording on both surfaces of the paper P in the printer  10 , the recording section  28  performs the recording on the first surface of the paper P, and then while the trailing edge of the paper when the recording is performed on the first surface becomes the leading edge thereof due to a backward feeding operation of the transportation rollers  64  and the discharge rollers  74 , the paper P is fed to the inverted path  78  which is positioned on the side further in the −Z direction than the second roller  52  in the Z axis direction. 
     The paper P fed to the inverted path  78  is nipped by the second roller  52  and the fourth transportation driven roller  60 , and is fed to the outer circumferential surface on the side further in the −Z direction than the first roller  50 . Along the outer circumferential surface of the first roller  50 , the paper P is nipped again by the first roller  50  and the fifth transportation driven roller  62 . Accordingly, the paper P is bent and inverted so that the first surface is on the bottom and the second surface is on the top. Thereafter, the paper P is fed along the transportation path to the recording section  28  by the transportations rollers  64  via the first roller  50 , the third transportation driven roller  58 , the second transportation driven roller  56 , the first transportation driven roller  54  and the second roller  52 . 
     For this reason, the second surface faces the recording head  70 . The recording section  28  performs recording on the second surface, and the paper P is nipped by the discharge rollers  74  and is discharged to the discharge stacker  76  that is provided on the front side of the apparatus. 
     As described above, in the printer  10 , since a plurality of the transportation driven rollers  54 ,  56 ,  58 ,  60  and  62  which are in contact with the first roller  50  and the second roller  52  are provided in the transportation section  26  along the transportation paths before and after the medium is inverted, the paper P can be smoothly transported in the transportation path and the inverted path  78 . 
     Since while the paper P fed from the recording head  70  to the inverted path  78  is nipped between the second roller  52  and the fourth transportation driven roller  60 , the paper P is transported toward the first roller  50 , it is possible to smoothly invert the medium in the first roller. 
     Transportation Unit 
     Subsequently, the transportation unit  66  will be described with reference to  FIGS. 6, 7A and 7B . The transportation unit  66  is configured to be attachable and detachable with respect to the apparatus main body  12 . A method for attaching and detaching the transportation unit  66  with respect to the apparatus main body  12  will be described later. 
     The transportation unit  66  includes a unit main body  82  and a cover section  84 . In the embodiment, a driven transmission unit  86  is provided in an end portion on the side further in the +X direction than the unit main body  82 . The driven transmission unit  86  includes a first transmission gear  88 , a second roller drive gear  90 , a second transmission gear  92  and a first roller drive gear  94 . The first transmission gear  88  engages with the second roller drive gear  90 , and the second roller drive gear  90  engages with the second transmission gear  92 , and the second transmission gear  92  engages with the first roller drive gear  94 . 
     The second roller drive gear  90  is connected to the second roller  52  via a shaft that is not illustrated. The first roller drive gear  94  is connected to the first roller  50  via a shaft that is not illustrated. 
     In a state where the transportation unit  66  is attached to the apparatus main body  12 , the driven transmission unit  86  of the transportation unit  66  is connected to a drive transmission unit  96  to be described later on a side of the apparatus main body  12 , and receives a drive force from the drive transmission unit  96 . That is, the driven transmission unit  86  drives the first roller  50  and the second roller  52  by using the drive force of the drive transmission unit  96  on the side of the apparatus main body  12 . Accordingly, it is not necessary to provide a driving source in the transportation unit  66 , and it is possible to prevent the weight of the transportation unit  66  from increasing. 
     In the embodiment, the first roller  50  and the second roller  52  are disposed in a center portion in a width direction (in an X axis direction in  FIG. 7A ) of the unit main body  82 . The first roller  50  is disposed on a back end side (on a side of a +Y direction in  FIG. 7A ) of the unit main body  82 . The second roller  52  is disposed with a gap on the side of the −Y direction from the first roller  50 . 
     In the embodiment, the first roller  50  and the second roller  52  are set to have a diameter of the same dimension. For this reason, the first roller  50  and the second roller  52  can be made of a common configuration member, and it is possible to achieve low costs. Since the first roller  50  and the second roller  52  have the same diameter, it is possible to easily set circumferential velocities of the outer circumferences of the rollers, that is, paper transportation velocities, to be equal to each other by setting the numbers of rotations of both rollers to be the same. Since the first roller  50  and the second roller  52  have a diameter of the same dimension, it is possible to horizontally maintain the paper P that is transported in the transportation path which is formed between the unit main body  82  and the cover section  84  to be described later. 
     Since the first roller  50  and the second roller  52  can have the same paper transportation velocity, tension or deflection is not exerted on the paper P between the first roller  50  and the second roller  52 . As a result, it is possible to reliably transport the paper P along the transportation path. 
     The first roller  50  and the second roller  52  are driven by a drive force from the first transmission gear  88 . For this reason, the first roller  50  and the second roller  52  can have a common driving source. For this reason, since it is not necessary to provide the driving source for each of the first roller  50  and the second roller  52 , it is possible to prevent costs from increasing. 
     Since the transportation unit  66  that is attachable and detachable with respect to the apparatus main body  12  is configured to have the first roller  50  and the second roller  52 , when the transportation unit  66  is detached from the apparatus main body  12 , the inverted path  78  provided in the apparatus main body  12  is exposed. Accordingly, it is possible to easily remove the jammed paper P when the paper P is jammed (when a paper jam occurs). 
     As illustrated in  FIGS. 6 and 7A , the cover section  84  has a configuration in which the cover section  84  is attached to a rotationally moving shaft that is provided on the side further in the −Y direction than the unit main body  82 , and can be opened and closed when the cover section  84  rotationally moves with respect to the unit main body  82 . Specifically, as illustrated in  FIG. 6 , the cover section  84  can be closed with respect to the unit main body  82 . As illustrated in  FIG. 7A , the cover section  84  can be opened with the unit main body  82 . As illustrated in  FIG. 7A , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  are rotatably provided on an inner surface  84   a  of the cover section  84 . 
     When the cover section  84  is closed with respect to the unit main body  82 , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  are disposed on the inner surface  84   a  to be in contact with the first roller  50  and the second roller  52  at the positions illustrated in  FIG. 5 . 
     That is, when the cover section  84  is closed with respect to the unit main body  82 , the first transportation driven roller  54  and the second transportation driven roller  56 , and the third transportation driven roller  58  are respectively in contact with the second roller  52  and the first roller  50 . When the cover section  84  is open with respect to the unit main body  82 , the first transportation driven roller  54  and the second transportation driven roller  56 , and the third transportation driven roller  58  respectively separate from the first roller  50  and the second roller  52 . 
     For this reason, when the cover section  84  is open, it is possible to easily remove the paper P, for example, a small piece of the paper P, jammed inside the transportation unit  66 . 
     The unit main body  82  includes an upper surface  82   a  and a lower surface  82   b . When the cover section  84  is closed with respect to the unit main body  82 , with a predetermined gap between the upper surface  82   a  and the inner surface  84   a , the upper surface  82   a  faces the inner surface  84   a  of the cover section  84 . That is, when the cover section  84  is closed with respect to the unit main body  82 , the upper surface  82   a  and the inner surface  84   a  form a part of the transportation path of the paper P. When the transportation unit  66  is attached to the apparatus main body  12 , the inverted path  78  (refer to  FIGS. 3 and 5 ) is formed between the lower surface  82   b  and a support plate  98  (refer to  FIGS. 3 and 5 ) of the apparatus main body  12 . 
     The first roller  50  and the second roller  52  protrude to the transportation path and the inverted path  78  from the upper surface  82   a  and the lower surface  82   b  of the unit main body  82 . Even when the cover section  84  is closed, the back end side (on the side of the Y direction in  FIG. 6 ) of the unit main body  82  is open and is exposed. 
     When the transportation unit  66  is mounted onto the apparatus main body  12 , and the back surface cover  22  is closed with respect to the apparatus main body  12 , the back end side (on the side of the Y direction in  FIG. 6 ) of the unit main body  82  faces the feeding path section  48  of the back surface cover  22 . Accordingly, the back end side of the unit main body  82  and the feeding path section  48  form a part of the transportation path from the medium container  20  and a part of the inverted path  78 . 
     The first roller  50  protrudes from the back end side of the unit main body  82  to the transportation path that is formed by the back end portion and the feeding path section  48 . For this reason, the outer circumferential surface of the first roller  50  protrudes to the transportation path and the inverted path from the upper surface  82   a , the back end side and the lower surface  82   b  of the unit main body  82 , and rotation of the first roller  50  can be used to transport the paper P. 
     In both end portions in a width direction (in an X axis direction in  FIG. 6 ) of the back end side (the side of the +Y direction in  FIG. 6 ) of the unit main body  82 , grasping sections  100  are provided to protrude to the side of the +Y direction. For this reason, when the transportation unit  66  is attached and detached with respect to the apparatus main body  12 , good workability is obtained. 
     In each end portion in the width direction (in an X axis direction in  FIG. 7B ) of the unit main body  82 , a protrusion  102  (refer to  FIGS. 6 and 7B ) is provided on the lower surface  82   b  of the unit main body  82  to protrude in a −Z direction in  FIG. 7B  from the lower surface  82   b . In each end portion in the width direction (in the X axis direction in  FIG. 6 ) of the back end side (the side of the +Y direction in  FIG. 6 ) of the unit main body  82 , a pressed section  104  is provided. The protrusion  102  and the pressed section  104  will be described in detail later. 
     Subsequently, the back surface cover  22  and a mounting section  106  (refer to  FIG. 10A ) of the transportation unit  66  of the apparatus main body  12  will be described with reference to  FIGS. 8, 9A, 9B, 10A and 10B . In  FIG. 8 , the back surface cover  22  is open with respect to the apparatus main body  12 . At this time, the transportation unit  66  is mounted onto the apparatus main body  12 . For this reason, when the back surface cover  22  and the medium support tray  24  provided on the back surface cover  22  are open with respect to the apparatus main body  12 , at least parts of the back end side (the side of the +Y direction in  FIG. 6 ) of the transportation unit  66  and the first roller  50  are exposed to the outside of the apparatus main body  12 . 
     Accordingly, a part of the transportation path from the medium container  20  and a part of the supply path from the medium support tray  24  are exposed to the outside of the apparatus main body  12 . In addition, at least a part of the first roller  50  is exposed, thereby causing the paper P jammed in the transportation path and the supply path to be exposed. Accordingly, it is possible to easily remove the paper P and to easily perform a paper jam release operation. 
     When the back surface cover  22  is open with respect to the apparatus main body  12 , the first roller  50  of the transportation unit  66  separates from the fifth transportation driven roller  62  that is provided on the inside of the back surface cover  22 . For this reason, when the paper P fed from the medium container  20  is jammed in the transportation path from the medium container  20 , it is possible to easily remove the paper P. 
     In  FIGS. 9A and 9B , the feeding path section  48  is provided on the inside of the back surface cover  22  to form a part of the transportation path. A pressing section  108  is provided in each end portion in an X axis direction in  FIG. 9A  of the back surface cover  22 . When the back surface cover  22  is closed with respect to the apparatus main body  12 , the pressing sections  108  are provided on the back surface cover  22  at positions where the pressing sections  108  engage with the pressed sections  104  of the transportation unit  66 . 
     Accordingly, when the transportation unit  66  is mounted onto the apparatus main body  12  and the back surface cover  22  is closed with respect to the apparatus main body  12 , the transportation unit  66  is mounted onto the apparatus main body  12 , the pressed section  104  and the pressing section  108  engage each other. That is, in a state where the back surface cover  22  is closed with respect to the apparatus main body  12 , the back surface cover  22  is in contact with the transportation unit  66  and thus, a closed posture of the back surface cover  22  is regulated. 
     For this reason, a relative position relationship between the back surface cover  22  and the transportation unit  66  is accurately determined. Accordingly, when the transportation path of the paper P is formed by the back surface cover and the transportation unit  66 , the feeding path section  48  of the back surface cover  22  faces the back end side of the transportation unit  66  while a proper gap is maintained between the feeding path section  48  and the back end side. As a result, it is possible to properly form the transportation path of the paper P. 
     Subsequently,  FIG. 10A  illustrates a state where the transportation unit  66  is detached from the apparatus main body  12 . When the back surface cover  22  is open, the apparatus main body  12  is provided with the mounting section  106  that is exposed toward the back surface side (a side of a +Y direction in  FIG. 10A ) of the apparatus. It is possible to mount the transportation unit  66  on the mounting section  106  by inserting the transportation unit  66  from the back surface side of the apparatus, that is, from the side of the +Y direction to a side of a −Y direction. 
     That is, since the transportation unit  66  is mounted onto the mounting section  106  that is exposed when the openable and closeable back surface cover  22  provided on the apparatus main body  12  is open, it is possible to prevent a user from unintentionally dropping the transportation unit  66 . Since the transportation unit  66  is not configured to have a member forming an exterior of the apparatus main body as an element, that is, the back surface cover  22  and the transportation unit  66  are separately configured, it is possible to reduce the weight of the transportation unit  66 , and to obtain good workability when attaching and detaching the transportation unit  66  with respect to the apparatus main body  12 . Even in a case where the size of the printer  10  becomes large, it is possible to prevent the weight of the transportation unit  66  from increasing, and to ensure good handleability. 
       FIG. 10B  illustrates an end portion on a side of a +X direction in a width direction (in an X axis direction in  FIGS. 10A and 10B ) of the mounting section  106 . On the support plate  98  forming the inverted path  78  of the apparatus main body  12 , a sloping surface  110  is provided in the end portion on the side of the +X direction in the width direction. The sloping surface  110  is provided in the end portion on the side further in the −X direction than the support plate  98  (not illustrated), and the sloping surface  110  engages with the protrusion  102  of the transportation unit  66  at a second position (refer to  FIG. 13A ) to be described to configure retention means  112  that retains the transportation unit  66  at the second position. 
     Transmission of Power to Transportation Unit 
     Subsequently, the following will be described with reference to  FIGS. 11A, 11B, 12A, 12B, 13A and 13B : a method for attaching and detaching the transportation unit  66  with respect to the apparatus main body  12  and a connection and disconnection of power transmission means. 
     In  FIGS. 11A and 11B , the drive transmission unit  96  of the apparatus main body  12  is connected to the driven transmission unit  86  of the transportation unit  66 . In a state where the drive transmission unit  96  and the driven transmission unit  86  are connected to each other, in the front and back direction (in a Y axis direction in  FIG. 11A ) of the apparatus, a position of the transportation unit  66  with respect to the apparatus main body  12  is referred to as a first position Y 1  (refer to  FIG. 11B ). 
     Herein, the drive transmission unit  96  is configured to have a gear train that is configured to have a plurality of gears. A drive gear  114  is positioned at one end of the row of gear train, and is connected to the drive motor  116 . A third transmission gear  118  is positioned at the other end thereof, and engages with the first transmission gear  88  of the driven transmission unit  86 . Herein, the drive transmission unit  96  is configured in such a manner that the third transmission gear  118  always rotates in a counter-clockwise direction no matter which direction the drive motor  116  rotates in. 
     For this reason, when the drive transmission unit  96  and the driven transmission unit  86  are connected to each other at the first position Y 1 , due to a rotational drive force of the drive motor  116 , the first roller drive gear  94  and the second roller drive gear  90 , that is, the first roller  50  and the second roller  52 , are rotationally driven in a counter-clockwise direction, that is, in a direction in which the paper P is fed along the transportation path. 
     Subsequently, a second position Y 2  will be described with reference to  FIGS. 12A, 12B and 13A . In the front and back direction (in a Y axis direction in  FIGS. 12B and 13A ) of the apparatus, the second position Y 2  (refer to  FIGS. 12B and 13A ) indicates a position at which the driven transmission unit  89  is positioned after the driven transmission unit  86  separates from the drive transmission unit  96 , that is, after the transportation unit  66  pulls out with respect to the first position Y 1 . 
     In  FIG. 12A , when the back surface cover  22  is open with respect to the apparatus main body  12 , the engagement between the pressed section  104  of the transportation unit  66  and the pressing section  108  is released. For this reason, the regulation in the Y axis direction of the transportation unit  66  is released with respect to the apparatus main body  12 . Accordingly, the transportation unit  66  can be displaced to a side of a +Y direction with respect to the apparatus main body  12 . 
     Herein, when a user grasps the grasping section  100  to slide the transportation unit  66  in the +Y direction, as illustrated in  FIG. 12B , the transportation unit  66  moves from the first position Y 1  to the second position Y 2  in the Y axis direction. Accordingly, the engagement between the third transmission gear  118  of the drive transmission unit  96  and the first transmission gear  88  of the driven transmission unit  86  is released. That is, the driven transmission unit  86  separates from the drive transmission unit  96 , and the drive force of the drive motor  116  is not transmitted to the driven transmission unit  86 . 
     For this reason, the first transmission gear  88 , the second roller drive gear  90 , the second transmission gear  92  and the first roller drive gear  94  of the driven transmission unit  86  are freely rotatable. Accordingly, the first roller  50  and the second roller  52  rotated by the driven transmission unit  86  are freely rotatable. 
     At this time, if the transportation unit  66  slides from the first position Y 1  to the second position Y 2 , the protrusion  102  of the transportation unit  66  engages with the sloping surface  110  that is provided on the support plate  98 . Accordingly, when a pullout force equal to or smaller than a predetermined magnitude is exerted on the transportation unit  66 , the transportation unit  66  is retained at the second position Y 2  in the Y axis direction by the retention means  112  that is configured to have the protrusion  102  and the sloping surface  110 . 
     Accordingly, in a state where the transportation unit  66  is mounted onto the apparatus main body  12 , the transportation unit  66  is configured to be displaceable between the first position Y 1  at which the driven transmission unit  86  is connected to the drive transmission unit  96  and the second position Y 2  at which the driven transmission unit  89  is positioned after the driven transmission unit  86  separates from the drive transmission unit  96 , that is, after the transportation unit  66  pulls out with respect to the first position Y 1 . 
     Furthermore, when a pullout force equal to or larger than a predetermined magnitude is exerted on the transportation unit  66 , the protrusion  102  climbs over the sloping surface  110  along a +Z direction in  FIG. 13A  and thus, the retention means  112  can release the retention of the transportation unit  66  at the second position Y 2 . For this reason, as shown in  FIG. 13B , the transportation unit  66  moves from the mounting section  106  of the apparatus main body  12  to the outside of the apparatus main body  12 , and is detached from the apparatus main body  12 . 
     That is, if a pullout force equal to or larger than a predetermined magnitude is applied to the transportation unit  66 , it is possible to pull out the transportation unit  66  from the mounting section  106 . Accordingly, when the transportation unit  66  is pulled out good workability is obtained compared to a configuration in which the transportation unit  66  is completely locked at the second position Y 2 . 
     When the transportation unit  66  is mounted onto the apparatus main body  12 , the transportation unit  66  is inserted onto the mounting section  106  in the +Y direction in  FIG. 13B . In a state where the transportation unit  66  is positioned at the second position Y 2  with respect to the apparatus main body  12 , the back surface cover  22  is closed with respect to the apparatus main body  12 . Accordingly, the pressing section  108  (refer to  FIG. 9A ) of the back surface cover  22  engages with the pressed section  104  (refer to  FIG. 8 ) of the transportation unit  66 , and the pressed section  104  is pressed in a −Y direction, and the transportation unit  66  is pressed into the first position Y 1 . Accordingly, the driven transmission unit  86  is connected to the drive transmission unit  96 , and a drive force from the drive motor  116  is transmitted to the driven transmission unit  86 . 
     Subsequently, when the paper P is jammed in the transportation path formed by the transportation unit  66 , a paper jam release process will be described with reference to  FIGS. 11A, 11B, 12A, 12B, 13A and 13B  again. 
     In  FIG. 11A , when the paper P is jammed in the transportation path, first, the back surface cover  22  is open with respect to the apparatus main body  12 . Accordingly, the transportation path from the medium container  20  to the transportation unit  66  is exposed and thus, it is possible to confirm the paper P that causes a paper jam. Accordingly, it is possible to easily remove the paper P that causes a paper jam in the transportation path from the medium container  20  to the transportation unit  66 . 
     Subsequently, when a paper jam occurs in a state where the paper P is nipped by the first roller  50 , the second roller  52 , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58 , if the back surface cover is open with respect to the apparatus main body  12 , a part of the paper P jammed on the outside, that is, on the back end side of the transportation unit  66 , is exposed. At this time, since the driven transmission unit  86  of the transportation unit  66  is connected to the drive transmission unit  96 , a force of pulling out the paper P nippped between the rollers is larger than a force of retaining the transportation unit  66  at the first position Y 1 . For this reason, when a user pulls out the paper P that is exposed to the outside from the back end side of the transportation unit  66 , it is possible to move the transportation unit  66  from the first position Y 1  to the second position Y 2 . 
     For this reason, since the driven transmission unit  86  of the transportation unit  66  separates from the drive transmission unit  96  at the second position Y 2 , a drive force is not transmitted to the transportation unit  66 . That is, since the first roller  50  and the second roller  52  of the transportation unit  66  are freely rotatable, it is possible to easily pull out the paper P in contact with the first roller  50  and the second roller  52 , and to easily perform a paper jam release operation. 
     Furthermore, even in a case where the paper P is nipped at multiple positions, when only a connection between the drive transmission unit  96  and the driven transmission unit  86  is released, a drive force is not transmitted to the entirety of the transportation unit  66 , that is, each of the rollers are freely rotatable at the multiple nipping positions (a position between the first roller  50  and the third transportation driven roller  58 , a position between the second roller  52  and the second transportation driven roller  56 , and a position between the second roller  52  and the first transportation driven roller  54 ) of the paper P. In a configuration in which the paper P is nipped at multiple positions, it is possible to avoid complexity of the structure and to easily remove the paper P. 
     When a user pulls out the paper P of which a part is nipped by the first roller  50 , the second roller  52 , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58 , and appears on the outside of the transportation unit  66 , that is, on the back end side thereof, the transportation unit  66  moves to the second position Y 2  and thus, it is not necessary for the user to move the transportation unit  66  from the first position Y 1  to the second position Y 2 , and good workability is obtained. 
     Since the printer  10  includes the retention means  112 , that is, the protrusion  102  and the sloping surface  110 , which retains the transportation unit  66  at the second position Y 2 , when the transportation unit  66  moves from the first position Y 1  to the second position Y 2 , the retention means  112  can prevent the transportation unit  66  from unintentionally returning to the first position Y 1  during a paper jam release operation of the paper P. 
     Since the printer  10  includes the retention means  112  that retains the transportation unit  66  at the second position Y 2 , when a user pulls out the paper P that is nipped by the first roller  50 , the second roller  52 , the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  in a state where the transportation unit  66  is retained at the second position Y 2 , the retention of transportation unit  66  at the second position Y 2  is maintained, and the paper P is pulled out from between the first roller  50  and the third transportation driven roller  58 , between the second roller  52  and the second transportation driven roller  56 , and between the second roller  52  and the first transportation driven roller  54 . 
     That is, since a force of retaining the transportation unit  66  at the second position Y 2  is larger than a force of pulling out the paper P from the transportation unit  66 , when the paper P is pulled out from the transportation unit  66 , it is possible to avoid such a problem that the transportation unit  66  is also pulled out from the apparatus main body  12  while being accompanied by the paper P. 
     Modification Example of First Embodiment 
     (1) In the configuration of the embodiment, one each of the first roller  50  and the second roller  52  are provided at the center in a direction that intersects with the transportation direction of the paper P, that is, in the width direction of the unit main body  82  of the transportation unit  66 . However, the embodiment may have a configuration in which at least any one of the first roller  50  and the second roller  52  is provided at multiple positions along the direction that intersects with the transportation direction of the paper P, that is, along the width direction of the unit main body  82 . In particular, in a configuration in which the plurality of second rollers  52  are provided in the width direction, since the paper P is in contact with the second roller  52  at multiple positions in the width direction of the paper P and thus, it is possible to suppress oblique feeding of the paper P during the transportation thereof. 
     (2) In a configuration in which at least any one of the first roller  50  and the second roller  52  is provided at multiple positions along the direction that intersects with the transportation direction of the paper P, that is, along the width direction of the unit main body  82 , a plurality of the first transportation driven rollers  54  and the second transportation driven rollers  56 , and a plurality of the third transportation driven rollers  58  may be provided to be respectively in contact with the second rollers  52  and the first rollers  50 . With this configuration, it is possible to further prevent the oblique feeding of the paper P during the transportation thereof. 
     (3) In the configuration of the embodiment, the protrusion  102  of the retention means  112  is provided on a side of the transportation unit  66 , and the sloping surface  110  of the retention means  112  is provided on a side of the apparatus main body  12 . However, the embodiment may have a configuration in which the protrusion  102  is provided on the side of the apparatus main body  12 , and the sloping surface  110  is provided on the side of the transportation unit  66 . 
     (4) In the configuration of the embodiment, the first roller  50  and the second roller  52  transport the paper P by using the outer circumferential surfaces thereof. However, the embodiment may have a configuration in which an endless belt is wound around between the first roller  50  and the second roller  52 , and the endless belt driven by rotation of the first roller  50  and the second roller  52  transports the paper P. 
     Second Embodiment 
       FIGS. 14 and 15  illustrate a printer  120  according to a second embodiment of the invention. The printer  120  is different from that of the first embodiment in that the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  are not provided on a transportation unit  122  but on an apparatus main body  124 . 
     As illustrated in  FIGS. 14 and 15 , the printer  120  is configured in such a manner that the transportation unit  122  is attachable and detachable with respect to the apparatus main body  124 . The back surface cover  22  is open and closed, and the transportation unit  122  is attached and detached with respect to the apparatus main body  124 . Similarly to in the first embodiment, the transportation unit  122  is provided with the first roller  50  and the second roller  52 . Similarly to in the first embodiment, when the transportation unit  122  is mounted onto the apparatus main body  124 , and the drive transmission unit  96  of the apparatus main body  124  is connected to the driven transmission unit  86  of the transportation unit  122 , the first roller  50  and the second roller  52  are rotationally driven by a drive force supplied from the apparatus main body  124 . 
     When the transportation unit  122  is mounted onto the apparatus main body  124 , the apparatus main body  124  is provided with the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  in such a manner that the first transportation driven roller  54  and the second transportation driven roller  56 , and the third transportation driven roller  58  are respectively in contact with the second roller  52  and the first roller  50 . 
     The pressed section  104  (refer to  FIGS. 6 and 8 ) is provided on a back end side of the transportation unit  122 . In contrast, the pressing section  108  (refer to  FIGS. 9A and 9B ) is provided on a side of the inner surface of the back surface cover  22 , that is, on a side of the back surface cover  22 , which faces the apparatus main body  124 . 
     In the embodiment, when the transportation unit  122  is mounted onto the apparatus main body  124 , and the back surface cover  22  is closed, the pressed section  104  and the pressing section  108  are in contact with each other, and the pressing section  108  presses the pressed section  104 . Accordingly, the transportation unit  122  moves from the second position Y 2  to a front side (a side of a −Y direction in  FIGS. 14 and 15 ) of the apparatus with respect to the apparatus main body  124 , and the transportation unit  122  is positioned at the first position Y 1 . Accordingly, the drive transmission unit  96  is connected to the driven transmission unit  86 , and the paper P can be transported. 
     When the transportation unit  122  is mounted onto the apparatus main body  124 , and the back surface cover  22  is open with respect to the apparatus main body  124 , the engagement between the pressed section  104  and the pressing section  108  is released. When the pressed section  104  and the pressing section  108  disengage each other, the apparatus main body  124  is provided with bias means which is not illustrated and biases the transportation unit  122  in a +Y direction in  FIG. 15 . Accordingly, in the embodiment, when the back surface cover  22  is open with respect to the apparatus main body  124 , the transportation unit  122  is displaced from the first position Y 1  to the second position Y 2  by the bias means which is not illustrated. 
     That is, in the embodiment, when the back surface cover  22  is closed, the transportation unit  122  is retained at the first position Y 1  by the back surface cover  22 . When the closed back surface cover  22  is open, the transportation unit  122  is displaced from the first position Y 1  to the second position. 
     Accordingly, since the transportation unit  122  is displaced from the first position Y 1  to the second position Y 2 , it is not necessary for a user to move the transportation unit  122  itself from the first position Y 1  to the second position Y 2 , and good workability is obtained. 
     Modification Example of Second Embodiment 
     (1) In the configuration of the embodiment, the first roller  50  and the second roller  52  are driven by a common drive motor  116 . In replacement of this configuration, the embodiment may have a configuration in which the first roller  50  and the second roller  52  are rotationally driven by independent drive motors, respectively. 
     (2) In the configuration of the embodiment, the first roller  50  and the second roller  52  have a diameter of the same dimension. In replacement of this configuration, the embodiment may have a configuration in which the first roller  50  and the second roller  52  have diameter dimensions that are different from each other. 
     (3) In the embodiment, one each of the first roller  50  and the second roller  52  is configured as a drive roller. However, in replacement of this configuration, a plurality of the first rollers  50  and the second rollers  52  are configured as drive rollers. 
     (4) Even in the configuration of the embodiment, at least any one of the first roller  50  and the second roller  52  may be provided at multiple positions along a direction that intersects with the transportation direction of the paper P, that is, along a width direction of the transportation unit  122 . A plurality of the first transportation driven roller  54 , the second transportation driven roller  56  and the third transportation driven roller  58  may be provided in a width direction of the apparatus main body  124 . 
     In addition, in each of the embodiments described above, the transportation units  66  and  122  are applied to an ink jet printer as an example of the recording apparatus. However, the transportation units  66  and  122  are also typically applicable to other liquid ejecting apparatuses. 
     Herein, the liquid ejecting apparatus is not limited to a printer, a copying machine, a facsimile and the like that uses an ink jet type recording head, and performs recording on a recording medium by discharging ink from the recording head. The liquid ejecting apparatus includes an apparatus that ejects liquid suitable for the purpose instead of ink on an ejected medium equivalent to the recorded medium from a liquid ejecting head equivalent to the ink jet type recording head, and adheres the liquid on the ejected medium. 
     In addition to the recording head describe above, there are following liquid ejecting heads: a color material ejecting head used in manufacturing a color filter such as a liquid crystal display; an electrode material (electric conductive paste) ejecting head used in forming an electrode of an organic EL display, a field emission display (FED) or the like; a living organic matter ejecting head used in manufacturing a biochip; a specimen ejecting head as a precision pipette; and the like. 
     The invention is not limited to the embodiments described above. The invention can be modified in various forms insofar as the modifications do not depart from the scope of the invention, which is described in the claims. The scope of the invention includes the modifications. 
     The entire disclosure of Japanese Patent Application No. 2013-072571 filed on Mar. 29, 2013, and No. 2013-071633 filed on Mar. 29, 2013 are expressly incorporated by reference herein.