Patent Publication Number: US-9417585-B2

Title: Image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2013-207240 filed Oct. 2, 2013. 
     BACKGROUND 
     Technical Field 
     The present invention relates to an image forming apparatus. 
     SUMMARY 
     According to an aspect of the invention, there is provided an image forming apparatus including: 
     plural image forming portions that form an image on a recording medium; and 
     a transport unit that transports the recording medium to at least one image forming portion selected among the plural image forming portions, 
     wherein the transport unit includes plural transport paths that are different at least in an image forming portion, to which the recording medium is transported, among the plural image forming portions, and in an order of the recording medium transported to each image forming portion constituting the image forming portion to which the recording medium is transported. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a diagram showing an image forming apparatus according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a diagram showing a state where a recording medium is transported using a first transport path of the image forming apparatus shown in  FIG. 1 ; 
         FIG. 3  is a diagram showing a state where the recording medium is transported using a second transport path of the image forming apparatus shown in  FIG. 1 ; 
         FIG. 4  is a diagram showing a state where the recording medium is transported using a third transport path of the image forming apparatus shown in  FIG. 1 ; 
         FIG. 5  is a diagram showing a state where the recording medium is transported using a fourth transport path of the image forming apparatus shown in  FIG. 1 ; 
         FIG. 6  is a diagram showing an image forming apparatus according to a second exemplary embodiment of the present invention; 
         FIG. 7  is a diagram showing a state where a recording medium is transported using a first transport path of the image forming apparatus shown in  FIG. 6 ; 
         FIG. 8  is a diagram showing a state where the recording medium is transported using a second transport path of the image forming apparatus shown in  FIG. 6 ; 
         FIG. 9  is a diagram showing a state where the recording medium is transported using a third transport path of the image forming apparatus shown in  FIG. 6 ; 
         FIG. 10  is a diagram showing a state where the recording medium is transported using a fourth transport path of the image forming apparatus shown in  FIG. 6 ; 
         FIG. 11  is a diagram showing a state where the recording medium is supplied from a first unwinding and rewinding device so that the image is formed on a rear surface of the wound recording medium in the image forming apparatus shown in  FIG. 1 ; 
         FIG. 12  is a diagram showing a state where the recording medium is rewound by the first unwinding and rewinding device so that a surface of the recording medium side, on which the image is formed, is toward the inner side, in the image forming apparatus shown in  FIG. 1 ; 
         FIG. 13  is a diagram showing a state where the recording medium is supplied from a second unwinding and rewinding device so that the image is formed on the rear surface of the wound recording medium in the image forming apparatus shown in FIG.  1 ; and 
         FIG. 14  is a diagram showing a state where the recording medium is rewound by the second unwinding and rewinding device so that the surface of the recording medium side, on which the image is formed, is toward the inner side, in the image forming apparatus shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Next, exemplary embodiments of the present invention will be described with reference to the drawings. 
       FIG. 1  shows an image forming apparatus  10  according to a first exemplary embodiment of the present invention. As shown in  FIG. 1 , the image forming apparatus  10  includes an image forming apparatus body  12 , and in the image forming apparatus body  12 , a first unwinding and rewinding device  30 , a second unwinding and rewinding device  40 , a first image forming portion  100 , a second image forming portion  200 , and a transport mechanism  400  are provided. The image forming apparatus  10  forms an image on a sheet that is used as a recording medium, and for example, forms an image on a web that is used as a recording medium continuously wound in a longitudinal direction, and the recording medium on which the image is formed is rewound to be wound in the longitudinal direction. 
     The first unwinding and rewinding device  30  may be used as an unwinder that supplies the sheet, may be used as a rewinder that rewinds the sheet on which the image is formed, and includes a rotating shaft  34  that is selected to move either in a direction shown by arrow a in  FIG. 1  or a direction shown by arrow b in  FIG. 1  and may be rotated. When the first unwinding and rewinding device  30  is used as the unwinder, in a case where the sheet is supplied (refer to  FIGS. 2, 3, and 4 ) so that the image is formed on a front surface (outer surface) of the wound sheet, the rotating shaft  34  is inserted into a hollow portion of the sheet wound in a roll shape and the sheet is mounted on the rotating shaft  34 , and the sheet is fed to the transport mechanism  400  by rotating the rotating shaft  34  in the arrow a direction. On the other hand, when the first unwinding and rewinding device  30  is used as the rewinder, in a case where the sheet is rewound (refer to  FIG. 5 ) so that the surface on which the image is formed is toward the outer side, a tip portion of the sheet is fixed to the rotating shaft  34 , and the sheet is rewound to be wound around the rotating shaft  34  by rotating the rotating shaft  34  in the arrow a direction. 
     When the first unwinding and rewinding device  30  is used as the unwinder and when the first unwinding and rewinding device  30  is used as the rewinder, the directions, in which the sheets are wound around the rotating shaft  34 , become directions opposite to each other. Moreover, when the first unwinding and rewinding device  30  is used as the unwinder, the first unwinding and rewinding device  30  may supply (refer to  FIG. 11 ) the sheet so that the image is formed on the rear surface of the wound sheet as described below, instead of supplying the sheet to form the image on the front surface of the wound sheet. Moreover, when the first unwinding and rewinding device  30  is used as the rewinder, the first unwinding and rewinding device  30  may rewind (refer to  FIG. 12 ) the sheet so that the surface on which the image is formed is toward the inner side as described below, instead of rewinding the sheet so that the surface on which the image is formed is toward the outer side in the state where the sheet is wound. 
     Moreover, the first unwinding and rewinding device  30  is disposed so that an upper end portion of the first unwinding and rewinding device  30  is positioned below a lower end portion of the first image forming portion  100  and a lower end portion of the second image forming portion  200  in the direction of gravity. Moreover, at least a portion of the first unwinding and rewinding device  30  is disposed below the first image forming portion  100  in the direction of gravity to overlap with the first image forming portion  100  in the direction of gravity. 
     Similar to the first unwinding and rewinding device  30 , the second unwinding and rewinding device  40  may be used as an unwinder that supplies the sheet, may be used as a rewinder that rewinds the sheet on which the image is formed, and includes a rotating shaft  44  that is selected to move either in a direction shown by the arrow a in  FIG. 1  or a direction shown by the arrow b in  FIG. 1  and may be rotated. When the second unwinding and rewinding device  40  is used as the unwinder, in a case where the sheet is supplied (refer to  FIG. 5 ) so that the image is formed on the front surface (outer surface) of the wound sheet, the rotating shaft  44  is inserted into a hollow portion of the sheet wound in a roll shape and the sheet is mounted on the rotating shaft  44 , and the sheet is fed to the transport mechanism  400  by rotating the rotating shaft  44  in the arrow a direction. On the other hand, when the second unwinding and rewinding device  40  is used as the rewinder, in a case where the sheet is rewound (refer to  FIGS. 2, 3, and 4 ) so that the surface on which the image is formed is toward the outer side, the tip portion of the sheet is fixed to the rotating shaft  44 , and the sheet is rewound to be wound around the rotating shaft  44  by rotating the rotating shaft  44  in the arrow a direction. 
     When the second unwinding and rewinding device  40  is used as the unwinder and when the second unwinding and rewinding device  40  is used as the rewinder, the directions, in which the sheets are wound around the rotating shaft  44 , become directions opposite to each other. Moreover, when the second unwinding and rewinding device  40  is used as the unwinder, the second unwinding and rewinding device  40  may supply (refer to  FIG. 13 ) the sheet so that the image is formed on the rear surface of the wound sheet as described below, instead of supplying the sheet to form the image on the front surface of the wound sheet. Moreover, when the second unwinding and rewinding device  40  is used as the rewinder, the second unwinding and rewinding device  40  may rewind (refer to  FIG. 14 ) the sheet so that the surface on which the image is formed is toward the inner side as described below, instead of rewinding the sheet so that the surface on which the image is formed is toward the outer side in the state where the sheet is wound. 
     Moreover, the second unwinding and rewinding device  40  is disposed so that an upper end portion of the second unwinding and rewinding device  40  is positioned below the lower end portion of the first image forming portion  100  and the lower end portion of the second image forming portion  200  in the direction of gravity. Moreover, at least a portion of the second unwinding and rewinding device  40  is disposed below the second image forming portion  200  in the direction of gravity to overlap with the second image forming portion  200  in the direction of gravity. 
       FIG. 1  shows a state where the first unwinding and rewinding device  30  is used as the unwinder that supplies the sheet and the second unwinding and rewinding device  40  is used as the rewinder that rewinds the sheet. 
     In the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40 , when one is used as the unwinder, the other is used as the rewinder. Moreover, a function of the first unwinding and rewinding device  30  and a function of the second unwinding and rewinding device  40  may be switched with each other. That is, as described above, the first unwinding and rewinding device  30  may be used as the unwinder, the second unwinding and rewinding device  40  may be used as the rewinder, the first unwinding and rewinding device  30  may be used as the rewinder, and the second unwinding and rewinding device  40  may be used as the unwinder. 
     As described above, instead of the function of the first unwinding and rewinding device  30  and the function of the second unwinding and rewinding device  40  being switched with each other, a position of the first unwinding and rewinding device  30  and a position of the second unwinding and rewinding device  40  may be switched with each other. For example, the first unwinding and rewinding device  30  is used as the unwinder that exclusively supplies the sheet and the second unwinding and rewinding device  40  is used to exclusively rewind the sheet, the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may be attached to and detached from the image forming apparatus body  12 , and dispositions of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  in the image forming apparatus body  12  may be switched with each other. 
     In addition, instead of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  having both the function of supplying the sheet wound in a roll shape in the longitudinal direction and the function of supplying the sheet to be wound in a roll shape in the longitudinal direction as described above, one of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may supply a folded web, and the other of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may rewind the sheet to be folded. In this case, preferably, the positions of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  are switched with each other. 
     In addition, instead of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  having both the function of supplying the sheet wound in a roll shape and the function of supplying the sheet to be wound in a roll shape as described above, for example, one of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may supply plural sheets cut into A4 size, A3 size, or the like, and the other of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may rewind the cut sheets. In this case, preferably, the positions of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  are switched with each other. 
     In addition, instead of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  being disposed in the image forming apparatus body  12 , at least one of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may be disposed outside the image forming apparatus body  12 . Moreover, at least one of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40  may be a device separated from the image forming apparatus  10 , and at least one of an insertion hole for inserting the sheet from the outside of the image forming apparatus body  12  and a discharge hole for discharging the sheet from the inside of the image forming apparatus body  12  may be provided in the image forming apparatus body  12 . 
     The first image forming portion  100  is one of plural image forming portions that form an image on the sheet, and includes a body portion  102 . For example, an insertion hole  104  used to insert the sheet is formed on a bottom surface of the body portion  102 . Moreover, a discharge hole  106  used to discharge the sheet, on which the image is formed, is formed on a side surface of the second image forming portion  200  side in the body portion  102 . In addition, a discharge hole  108  used to discharge the sheet, on which the image is formed, is formed on a side surface opposite to the second image forming portion  200  side in the body portion  102 . Either the discharge hole  106  or the discharge hole  108  is used according to whether any one of a first transport path  412 , a second transport path  414 , a third transport path  416 , and a fourth transport path  418  described below is used. Moreover, the body portion  102  may not be provided, and each member configuring the first image forming portion  100  described below may be directly disposed inside the image forming apparatus body  12 . 
     Moreover, the first image forming portion  100  includes a toner image forming portion  110 Y for forming a yellow toner image, a toner image forming portion  110 M for forming a magenta toner image, a toner image forming portion  110 C for forming a cyan toner image, and a toner image forming portion  110 K for forming a black toner image. Each of the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, and the toner image forming portion  110 K is used as a single color image forming portion that forms a single color image, and for example, adopts an electrophotographic method. Moreover, for example, each of the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, and the toner image forming portion  110 K includes a photoconductor  112  on which a latent image is formed by a latent image forming device (not shown) such as a laser irradiation device, and a developing device  114  that develops the latent image formed on the photoconductor  112  using toner. 
     In addition, each of the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, and the toner image forming portion  110 K includes a charging device (not shown) that charges a surface of the photoconductor  112 , a primary transfer device (not shown) for transferring the toner image to an intermediate image transfer belt  120  described below, and a cleaning device (not shown) that cleans the surface of the photoconductor  112  after the toner image is transferred. 
     Moreover, the first image forming portion  100  includes the intermediate image transfer belt  120 , the toner images formed by the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, and the toner image forming portion  110 K are transferred to be overlapped on the surface of the intermediate image transfer belt  120 , and the toner images transferred to be overlapped are transferred to the sheet by a secondary transfer device  122 . 
     Moreover, the first image forming portion  100  includes a fixing device  130  that fixes the toner image transferred to the sheet with respect to the sheet using heat and pressure, for example. 
     The second image forming portion  200  is one of plural image forming portions that form an image on the sheet, and includes a body portion  202 . For example, an insertion hole  204  used to insert the sheet is formed on a bottom surface of the body portion  202 . Moreover, a discharge hole  206  used to discharge the sheet, on which the image is formed, is formed on a side surface opposite to the first image forming portion  100  side in the body portion  202 . In addition, a discharge hole  208  used to discharge the sheet, on which the image is formed, is formed on a side surface of the first image forming portion  100  side in the body portion  202 . Either the discharge hole  206  or the discharge hole  208  is used according to whether any one of the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418  described below is used. Moreover, the body portion  202  may not be provided, and each member configuring the second image forming portion  200  described below may be directly disposed inside the image forming apparatus body  12 . 
     Moreover, the second image forming portion  200  includes a toner image forming portion  210 W for forming a white toner image, a toner image forming portion  210 G for forming a gold toner image, a toner image forming portion  210 S for forming a silver toner image, and a toner image forming portion  210 T for forming a transparent toner image. Each of the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T is used as a single color image forming portion that forms a single color image, and for example, adopts an electrophotographic method. Moreover, each of the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T includes a photoconductor  212  on which a latent image is formed by a latent image forming device (not shown) such as a laser irradiation device, and a developing device  214  that develops the latent image formed on the photoconductor  212  using toner. 
     In addition, each of the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T includes a charging device (not shown) that charges a surface of the photoconductor  212 , a primary transfer device (not shown) for transferring the toner image to an intermediate image transfer belt  220  described below, and a cleaning device (not shown) that cleans the surface of the photoconductor  212  after the toner image is transferred. 
     Moreover, the second image forming portion  200  includes the intermediate image transfer belt  220 , the toner images formed by the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T are transferred to be overlapped on the surface of the intermediate image transfer belt  220 , and the toner images transferred to be overlapped are transferred to the sheet by a secondary transfer device  222 . 
     Moreover, the second image forming portion  200  includes a fixing device  230  that fixes the toner image transferred to the sheet with respect to the sheet using heat and pressure, for example. 
     The transport mechanism  400  is used as a transport unit that transports the sheet to at least one image forming portion that is selected from the first image forming portion  100  and the second image forming portion  200 . In addition, the transport mechanism  400  includes plural transport paths that are different at least in the image forming portion, to which the sheet is transported, out of the first image forming portion  100  and the second image forming portion  200 , and in an order of the sheet transported with respect to each image forming portion on which the image is formed. More specifically, the transport mechanism  400  includes the first transport path  412  (refer to  FIG. 2 ) through which the sheet is transported to the first image forming portion  100  and the sheet is not transported to the second image forming portion  200 , the second transport path  414  (refer to  FIG. 3 ) through which the sheet is transported to the second image forming portion  200  and the sheet is not transported to the first image forming portion  100 , the third transport path  416  (refer to  FIG. 4 ) through which the sheet is transported to the second image forming portion  200  after the sheet is transported to the first image forming portion  100 , and the fourth transport path  418  (refer to  FIG. 5 ) through which the sheet is transported to the first image forming portion  100  after the sheet is transported to the second image forming portion  200 . In the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418 , only the third transport path  416  is shown in  FIG. 1 . Moreover, the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418  overlap with one another in at least a portion. 
     In addition, the transport mechanism  400  includes plural rollers that are disposed at positions along one or more paths of the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418  to transport the sheet. That is, the transport mechanism  400  includes a transport roller  432 , a transport roller  434 , a transport roller  436 , a transport roller  438 , a transport roller  440 , a transport roller  442 , a transport roller  444 , and a transport roller  446 . All or a portion of the rollers may be rotated in both directions, the rotation direction of the roller is switched, and thus, the direction in which the sheet is transported may be switched in at least a portion of the transport mechanism  400 . 
       FIG. 2  shows the image forming apparatus  10  in which the sheet is transported using the first transport path  412 . In this state, the sheet, which is supplied from the first unwinding and rewinding device  30  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  432 , the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet, which is discharged from the body portion  102  to pass through the discharge hole  106 , is transported to the second unwinding and rewinding device  40  by the transport roller  434 , the transport roller  436 , the transport roller  438 , and the transport roller  442  without being transported to the second image forming portion  200 , and thus, the sheet is rewound by the second unwinding and rewinding device  40  so that the surface of the sheet on which the image is formed is toward the outer side. In the state where the first transport path  412  is used, the image may be formed on the sheet by only the first image forming portion  100 , and the image is not formed on the sheet by the second image forming portion  200 . 
       FIG. 3  shows the image forming apparatus  10  in which the sheet is transported using the second transport path  414 . In this state, the sheet, which is supplied from the first unwinding and rewinding device  30  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  432 , the transport roller  436 , and the transport roller  438 , the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet, which is discharged from the body portion  202  to pass through the discharge hole  206 , is transported to the second unwinding and rewinding device  40  by the transport roller  440  and the transport roller  442 , and thus, the sheet is rewound by the second unwinding and rewinding device  40  so that the surface of the sheet on which the image is formed is toward the outer side. In the state where the second transport path  414  is used, the image may be formed on the sheet by only the second image forming portion  200 , and the image is not formed on the sheet by the first image forming portion  100 . 
       FIG. 4  shows the image forming apparatus  10  in which the sheet is transported using the third transport path  416 . In this state, the sheet, which is supplied from the first unwinding and rewinding device  30  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  432 , the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet, which is discharged from the body portion  102  to pass through the discharge hole  106 , is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  434 , the transport roller  436 , and the transport roller  438 . Moreover, the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet discharged to pass through the discharge hole  206  is transported to the second unwinding and rewinding device  40  by the transport roller  440  and the transport roller  442 , and thus, the sheet is rewound by the second unwinding and rewinding device  40  so that the surface of the sheet on which the image is formed is toward the outer side. In this state, the image is formed on the sheet by the first image forming portion  100 , and an image is formed on the sheet by the second image forming portion  200  to overlap with the sheet on which the image is formed by the first image forming portion  100 . 
       FIG. 5  shows the image forming apparatus  10  in which the sheet is transported using the fourth transport path  418 . In this state, the sheet, which is supplied from the second unwinding and rewinding device  40  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  438 , the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet, which is discharged from the body portion  202  to pass through the discharge hole  208 , is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  434 , the transport roller  436 , and the transport roller  432 . In addition, the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet discharged to pass through the discharge hole  108  is transported to the first unwinding and rewinding device  30  by the transport roller  444  and the transport roller  446 , and thus, the sheet is rewound by the first unwinding and rewinding device  30  so that the surface of the sheet on which the image is formed is toward the outer side. In this state, the image is formed on the sheet by the second image forming portion  200 , and an image is formed on the sheet by the first image forming portion  100  to overlap with the sheet on which the image is formed by the second image forming portion  200 . 
     As describe above, in the image forming apparatus  10  according to the first exemplary embodiment, the image may be formed on the sheet only by the first image forming portion  100  using the first transport path  412 , the image may be formed on the sheet only by the second image forming portion  200  using the second transport path  414 , an image may be formed by the second image forming portion  200  to overlap with the image formed by the first image forming portion  100 , using the third transport path  416 , and an image may be formed by the first image forming portion  100  to overlap with the image formed by the second image forming portion  200 , using the fourth transport path  418 . 
       FIG. 6  shows the image forming apparatus  10  according to a second exemplary embodiment of the present invention. In the image forming apparatus  10  according to the above-described first exemplary embodiment, the insertion hole  104  is formed on the bottom surface of the body portion  102 , and the insertion hole  204  is formed on the bottom surface of the body portion  202 . On the other hand, in the image forming apparatus  10  according to the second exemplary embodiment, the insertion hole  104  is formed on the side surface of the second image forming portion  200  side of the body portion  102 , and the insertion hole  204  is formed on the side surface of the side opposite to the first image forming portion  100  of the body portion  202 . Moreover, in the image forming apparatus  10  according to the above-described first exemplary embodiment, two discharge holes are formed on both the body portion  102  and the body portion  202 . On the other hand, in the second exemplary embodiment, one discharge hole  106  is formed on the body portion  102 , and one discharge hole  206  is formed on the body portion  202 . That is, the discharge hole  106  is formed on the side surface of the side opposite to the second image forming portion  200  of the body portion  102 , and the discharge hole  206  is formed on the side surface of the first image forming portion  100  side of the body portion  202 . 
     Moreover, similar to the image forming apparatus  10  according to the above-described first exemplary embodiment, the transport mechanism  400  included in the image forming apparatus  10  according to the second exemplary embodiment includes the first transport path  412  (refer to  FIG. 7 ) through which the sheet is transported to the first image forming portion  100  and the sheet is not transported to the second image forming portion  200 , the second transport path  414  (refer to  FIG. 8 ) through which the sheet is transported to the second image forming portion  200  and the sheet is not transported to the first image forming portion  100 , the third transport path  416  (refer to  FIG. 9 ) through which the sheet is transported to the second image forming portion  200  after the sheet is transported to the first image forming portion  100 , and the fourth transport path  418  (refer to  FIG. 10 ) through which the sheet is transported to the first image forming portion  100  after the sheet is transported to the second image forming portion  200 . However, between the image forming apparatus  10  according to the secondary exemplary embodiment and the above-described image forming apparatus  10  according to the first exemplary embodiment, there is a difference that dispositions of respective transport paths in the image forming apparatus body  12  are different from each other. In the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418 , only the fourth transport path  418  is shown in  FIG. 6 . Moreover, the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418  overlap with one another in at least a portion. 
     In addition, the transport mechanism  400  includes plural rollers that are disposed at positions along one or more paths of the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418  to transport the sheet. That is, the transport mechanism  400  includes a transport roller  452 , a transport roller  454 , a transport roller  456 , a transport roller  458 , a transport roller  460 , a transport roller  462 , a transport roller  464 , a transport roller  466 , a transport roller  468 , a transport roller  470 , a transport roller  476 , and a transport roller  478 . All or a portion of the rollers may be rotated in both directions, the rotation direction of the roller is switched, and thus, the direction in which the sheet is transported may be switched in at least a portion of the transport mechanism  400 . 
     Moreover, in  FIG. 6 , the developing device  114  shown in  FIG. 1  is not shown. However, each of the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, the toner image forming portion  110 K, the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T includes the developing device. In addition, with respect to the same portions as the configurations of the image forming apparatus  10  according to the first exemplary embodiment shown in  FIG. 1 , the same reference numerals as those of  FIG. 1  are assigned to  FIG. 6 , and descriptions thereof are omitted. 
       FIG. 7  shows the image forming apparatus  10  in which the sheet is transported using the first transport path  412 . In this state, the sheet, which is supplied from the second unwinding and rewinding device  40  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  452  and the transport roller  454 , the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet, which is discharged from the body portion  102  to pass through the discharge hole  106 , is transported to the first unwinding and rewinding device  30  by the transport roller  456  and the transport roller  458  without being transported to the second image forming portion  200 , and thus, the sheet is rewound by the first unwinding and rewinding device  30  so that the surface of the sheet on which the image is formed is toward the outer side. In the state where the first transport path  412  is used, the image may be formed on the sheet by only the first image forming portion  100 , and the image is not formed on the sheet by the second image forming portion  200 . 
       FIG. 8  shows the image forming apparatus  10  in which the sheet is transported using the second transport path  414 . In this state, the sheet, which is supplied from the second unwinding and rewinding device  40  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  460  and the transport roller  462 , the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet, which is discharged from the body portion  202  to pass through the discharge hole  206 , is transported to the first unwinding and rewinding device  30  by the transport roller  464  and the transport roller  452 , and thus, the sheet is rewound by the first unwinding and rewinding device  30  so that the surface of the sheet on which the image is formed is toward the outer side. In the state where the second transport path  414  is used, the image may be formed on the sheet by only the second image forming portion  200 , and the image is not formed on the sheet by the first image forming portion  100 . 
       FIG. 9  shows the image forming apparatus  10  in which the sheet is transported using the third transport path  416 . In this state, the sheet, which is supplied from the first unwinding and rewinding device  30  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  466  and the transport roller  454 , the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet, which is discharged from the body portion  102  to pass through the discharge hole  106 , is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  470 , a transport roller  472 , a transport roller  474 , and the transport roller  476 . Moreover, the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet discharged from the discharge hole  206  is transported to the second unwinding and rewinding device  40  by the transport roller  464  and the transport roller  478 , and thus, the sheet is rewound by the second unwinding and rewinding device  40  so that the surface of the sheet, on which the image is formed is toward the outer side. In this state, the image is formed on the sheet by the first image forming portion  100 , and an image is formed on the sheet by the second image forming portion  200  to overlap with the sheet on which the image is formed by the first image forming portion  100 . 
       FIG. 10  shows the image forming apparatus  10  in which the sheet is transported using the fourth transport path  418 . In this state, the sheet, which is supplied from the second unwinding and rewinding device  40  so that the image is formed on the front surface of the wound sheet, is fed into the body portion  202  to pass through the insertion hole  204  by the transport roller  460  and the transport roller  462 , the toner image is transferred to the sheet by the secondary transfer device  222 , the sheet, which is discharged from the body portion  202  to pass through the discharge hole  206 , is fed into the body portion  102  to pass through the insertion hole  104  by the transport roller  464 , the transport roller  452 , and the transport roller  454 . In addition, the toner image is transferred to the sheet by the secondary transfer device  122 , the sheet discharged to pass through the discharge hole  106  is transported to the first unwinding and rewinding device  30  by the transport roller  456  and the transport roller  458 , and thus, the sheet is rewound by the first unwinding and rewinding device  30  so that the surface of the sheet on which the image is formed is toward the outer side. In the state where the fourth transport path  418  is used, the image is formed on the sheet by the second image forming portion  200 , and an image is formed on the sheet by the first image forming portion  100  to overlap with the sheet on which the image is formed by the second image forming portion  200 . 
     As described above, similar to the image forming apparatus according to the above-described first exemplary embodiment, also in the image forming apparatus  10  according to the second exemplary embodiment, the image may be formed on the sheet only by the first image forming portion  100  using the first transport path  412 , the image may be formed on the sheet only by the second image forming portion  200  using the second transport path  414 , an image may be formed by the second image forming portion  200  to overlap with the image formed by the first image forming portion  100 , using the third transport path  416 , and an image may be formed by the first image forming portion  100  to overlap with the image formed by the second image forming portion  200 , using the fourth transport path  418 . 
     In each exemplary embodiment described above, for example, out of the first transport path  412 , the second transport path  414 , the third transport path  416 , and the fourth transport path  418 , the one that may be used as the transport path may be determined by operating an operating unit (not shown) such as an operating panel and by deciding the rotation direction of each transport roller  432  or the like, in a state when forming of an image with respect to a new web or the like starts, the sheet is mounted on either the first unwinding and rewinding device  30  or the second unwinding and rewinding device  40  according to the selected transport path, the sheet is mounted so that the sheet is transported to each transport roller according to the selected transport path, the tip portion of the sheet is fixed to the rotating shaft (rotating shaft  34  or rotating shaft  44 ) of the other of the first unwinding and rewinding device  30  and the second unwinding and rewinding device  40 . 
       FIG. 11  is a diagram showing a state where the sheet is supplied from the first unwinding and rewinding device  30  so that the image is formed on the rear surface of the wound sheet in the image forming apparatus  10  according to the first exemplary embodiment. In the above descriptions, although any transport path is used, when the first unwinding and rewinding device  30  is used as the unwinder, the example, in which the first unwinding and rewinding device  30  supplies the sheet so that the image is formed on the front surface of the wound sheet, is described (refer to  FIGS. 2, 3, and 4 ). However, as shown in  FIG. 11 , in the image forming apparatus  10  according to the first exemplary embodiment, the first unwinding and rewinding device  30  may supply the sheet so that an image is formed on the rear surface of the wound sheet. 
     In this case, as shown in  FIG. 11 , the sheet is attached to the rotating shaft  34  so that the direction of the sheet wound in the roll shape is opposite to the case shown in  FIG. 2  or the like, and the rotating shaft  34  is controlled to be rotated in the arrow b direction. Moreover, the sheet is transported in the body portion  102  to pass through the insertion hole  104  by the transport roller  432 . 
       FIG. 12  shows a state where the sheet is rewound by the first unwinding and rewinding device  30  so that the surface of the sheet side, on which the image is formed, is toward the inner side, in the image forming apparatus  10  according to the first exemplary embodiment. In the above descriptions, when the first unwinding and rewinding device  30  is used as the rewinder using the fourth transport path  418 , the example, in which the first unwinding and rewinding device  30  rewinds the sheet so that the surface of the sheet side on which the image is formed is toward the outer side, is described (refer to  FIG. 5 ). However, as shown in  FIG. 12 , in the image forming apparatus  10  according to the first exemplary embodiment, the first unwinding and rewinding device  30  may rewind the sheet to be wound so that the surface of the sheet, on which the image is formed, is toward the inner side. In this case, the rotating shaft  34  is controlled to be rotated in the arrow b direction. 
       FIG. 13  shows a state where the sheet is supplied from the second unwinding and rewinding device  40  so that the image is formed on the rear surface of the wound sheet in the image forming apparatus  10  according to the first exemplary embodiment. In the above descriptions, when the second unwinding and rewinding device  40  is used as the unwinder using the fourth transport path  418 , the example, in which the second unwinding and rewinding device  40  supplies the sheet so that the image is formed on the front surface of the wound sheet, is described (refer to  FIG. 5 ). However, as shown in  FIG. 13 , in the image forming apparatus  10  according to the first exemplary embodiment, the second unwinding and rewinding device  40  may supply the sheet so that the image is formed on the rear surface of the wound sheet. 
     In this case, as shown in  FIG. 13 , the sheet is attached to the rotating shaft  44  so that the direction of the sheet wound in the roll shape is opposite to the case shown in  FIG. 5 , and the rotating shaft  44  is controlled to be rotated in the arrow b direction. Moreover, the sheet is transported in the body portion  202  to pass through the insertion hole  204  by the transport roller  438 . 
       FIG. 14  shows a state where the sheet is rewound by the second unwinding and rewinding device  40  so that the surface of the sheet side, on which the image is formed, is toward the inner side, in the image forming apparatus  10  according to the first exemplary embodiment. In the above descriptions, although any transport path is used, when the second unwinding and rewinding device  40  is used as the rewinder, the example, in which the second unwinding and rewinding device  40  rewinds the sheet so that the surface of the sheet on which the image is formed is toward the outer side, is described (refer to  FIGS. 2, 3, and 4 ). However, as shown in  FIG. 14 , in the image forming apparatus  10  according to the first exemplary embodiment, the second unwinding and rewinding device  40  may rewind the sheet to be wound so that the surface of the sheet side, on which the image is formed, is toward the inner side. In this case, the rotating shaft  44  is controlled to be rotated in the arrow b direction. 
     As described above, in the image forming apparatus  10  according to the first exemplary embodiment, for example, according to whether the sheet is wound so that the surface of the side selected when the image forming of the sheet is performed becomes the front side, whether the sheet is wound so that the surface of the side selected when the image forming of the sheet is performed becomes the rear side, or the like, whether the image is formed on the front surface of the wound sheet or whether the image is formed on the rear surface of the wound sheet may be selected. Moreover, as described above, in the image forming apparatus  10  according to the first exemplary embodiment, according to circumstances of post processing such as the sheet having the formed image being separated to be plural sheets or the sheet having the formed image is drawn out, whether the sheet is rewound so that the surface of the side on which the image is formed is toward the outer side or whether the sheet is rewound so that the surface of the side on which the image is formed is toward the inner side may be selected. 
     Similar to the descriptions in the image forming apparatus  10  according to the first exemplary embodiment, in the image forming apparatus  10  according to the second exemplary embodiment, the sheet may be supplied from the first unwinding and rewinding device  30  so that the image is formed on the rear surface of the wound sheet, the sheet may be rewound by the first unwinding and rewinding device  30  so that the surface of the sheet side on which the image is formed is toward the inner side, the sheet may be supplied from the second unwinding and rewinding device  40  so that the image is formed on the rear surface of the wound sheet, and the sheet may be rewound by the second unwinding and rewinding device  40  so that the surface of the sheet side on which the image is formed is toward the inner side. 
     In addition, in each exemplary embodiment described above, the example in which the plural image forming portions include two image forming portions such as the first image forming portion  100  and the second image forming portion  200  is described. However, the present invention may also be applied to an apparatus including three or more image forming portions such as three image forming portions. 
     Moreover, in each exemplary embodiment described above, the case where the first image forming portion  100  includes four toner image forming portions used as the single color image forming portions such as the toner image forming portion  110 Y, the toner image forming portion  110 M, the toner image forming portion  110 C, and the toner image forming portion  110 K, and the second image forming portion  200  includes the toner image forming portions used as four single color image forming portions such as the toner image forming portion  210 W, the toner image forming portion  210 G, the toner image forming portion  210 S, and the toner image forming portion  210 T is described as an example. However, the number of the single color image forming portions included in each image forming portion is not necessarily four, and the number of the single color image forming portions included in each image forming portion may be appropriately determined. 
     As described above, for example, the present invention may be applied to at least an image forming apparatus such as a printer, a fax machine, a copier, or a printing machine. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.