Patent Publication Number: US-8123422-B2

Title: Image forming apparatus and opening/closing method of re-conveyance mechanism

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of application Ser. No. 11/676,573 filed Feb. 20, 2007, the entire contents of which is hereby incorporated by reference. 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Applications No. 2006-42769 filed on Feb. 20, 2006 and No. 2006-136775 filed on May 16, 2006, the entire contents of both of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an image forming apparatus such as a copying machine or a printer that can provide improved maintenance efficiency for the apparatus main body. 
     2. Description of the Related Art 
     A conventional image forming apparatus such as copying machines and printers include those equipped with an automatic duplex unit (to be referred to as ADU hereinafter). An ADU operates to feed a sheet bearing a fixed toner image at least on one of the opposite sides thereof feed to the image transfer position of the image forming apparatus once again. 
     In some image forming apparatus of the type under consideration, the ADU is arranged at a lateral side of the apparatus main body at a position adjacent to the sheet conveyance route in the apparatus main body. With this arrangement, the apparatus main body can be downsized and an ADU can be commonly used in a plurality of image forming apparatus manufactured with different sets of specifications. 
     With conventionally techniques, when an ADU is arranged at a lateral side of the apparatus main body and a jam accident arises, the ADU is turned around the lower end thereof that operates as fulcrum and then the lateral side of the apparatus main body is opened to dissolve the jam. For example Jpn. Pat. Publication (Kokai) No. 2005-115218, Jpn. Pat. Publication (Kokai) No. 2005-31353 and Jpn. Pat. Publication (Kokai) No. 2001-2330 discloses such techniques. 
     In some image forming apparatus technology in recent years, the lateral side of the apparatus main body where an ADU is arranged provides an access point for not only dissolve the jam but also maintenance the units in the apparatus main body. 
     However, in such conventional apparatus, the angle by which the ADU can be turned relative to the apparatus main body is limited to such an extent that the inside of the apparatus main body can be accessed only for dissolving the jam. In this reason, the ADU has to be removed from the apparatus main body when the lateral side of the apparatus main body needs to be opened wide for the purpose of maintenance the units in the inside of the apparatus main body, thus the workability of maintenance could have been went down. In this reason, the ADU and the apparatus main body are linked to each other by wires for driving the sheet feeding rollers and other components. Then, it is a cumbersome operation to find an appropriate location for temporarily put the ADU. Additionally, the wires connecting the apparatus main body and the ADU may be subjected to an undesired load. 
     Therefore, it is desired for image forming apparatus equipped with an ADU that is arranged at a lateral side of the apparatus main body that the ADU can be turned at a large angle relative to the lateral side of the apparatus main body to improve the maintenance efficiency. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to increase the angle by which the ADU is turned so that the corresponding lateral side of the apparatus main body may be opened wide with a simple operation. Then, as a result the inside of the apparatus main body can be accessed with ease to improve the efficiency of maintenance. 
     According to an embodiment of the present invention, there is provided an image forming apparatus comprising: a re-conveyance mechanism arranged at the lateral side of an apparatus main body so that it can be opened and closed relative to the apparatus main body, for feeding a transfer medium to an image transfer position of the apparatus once again; and an opening/closing mechanism having a first fulcrum for opening/closing the re-conveyance mechanism by a first angle relative to the apparatus main body and a second fulcrum for opening/closing the re-conveyance mechanism by a second angle that is greater than the first angle relative to the apparatus main body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic front view of the first embodiment of the present invention, which is a color copying machine; 
         FIG. 2  is a schematic illustration of the color copying machine according to the first embodiment of the present invention, showing the configuration thereof; 
         FIG. 3  is a schematic perspective view of the lateral side cover and the support section thereof according to the first embodiment of the present invention, showing the configuration thereof; 
         FIG. 4  shows schematic plan views of one of the stationary side plates and the corresponding one of the movable side support plates according to the first embodiment of the present invention as viewed in the respective directions indicated by arrows A 1  and A 2  in  FIG. 3 ; 
         FIG. 5  is a schematic front view of the first embodiment of the present invention, showing how the lateral side cover is opened and closed when dissolving a jam; 
         FIG. 6  shows other schematic plan views of one of the stationary side plates and the corresponding one of the movable side support plates according to the first embodiment of the present invention when a jam is to be dissolved as viewed in the respective directions indicated by arrows A 1  and A 2  in  FIG. 3 ; 
         FIG. 7  is a schematic front view of the first embodiment of the present invention, showing how the lateral side cover is opened and closed when maintenance the apparatus; 
         FIG. 8  shows other schematic plan views of one of the stationary side plates and the corresponding one of the movable side support plates according to the first embodiment of the present invention when the apparatus is maintained as viewed in the respective directions indicated by arrows A 1  and A 2  in  FIG. 3 ; 
         FIG. 9  is a schematic illustration of the second embodiment of the present invention, which is a color copying machine, showing the positional arrangement of an intermediate transfer belt, an ADU and a TRU; 
         FIG. 10  is a schematic perspective view of the ADU, the front bracket and the rear bracket according to the second embodiment of the present invention; 
         FIG. 11  is a schematic illustration of the ADU and the front bracket according to the second embodiment of the present invention; 
         FIG. 12  is an exploded schematic perspective view of the lower frame, the front bracket and the rear bracket according to the second embodiment of the present invention; 
         FIG. 13  is an enlarged schematic perspective view of part of  FIG. 12  according to the second embodiment of the present invention; 
         FIG. 14  is a schematic perspective view of the lower frame, the front bracket and the rear bracket according to the second embodiment of the present invention; 
         FIG. 15  is a schematic illustration of the pin of the TRU, the front bracket and the rear bracket according to the second embodiment of the present invention; 
         FIG. 16  is a schematic illustration of the lower frame, the front bracket and the rear bracket when the ADU is closed according to the second embodiment of the present invention; 
         FIG. 17  is a schematic illustration of the second embodiment of the present invention, showing how the ADU is opened to dissolve a jam; 
         FIG. 18  is a schematic illustration of the second embodiment of the present invention, showing how the TRU is opened to dissolve a jam; 
         FIG. 19  is a schematic lateral view of the lower frame, the front bracket and the rear bracket when the ADU is opened by 50 degrees according to the second embodiment of the present invention, showing partly as a see through view; 
         FIG. 20  is a schematic illustration of the ADU according to the second embodiment of the invention, showing how the fulcrum of rotation thereof slides from the first hole section to the second hole section; 
         FIG. 21  is a schematic illustration of the ADU according to the second embodiment of the present invention, showing how the fulcrum of rotation thereof slides from the second hole section to the first hole section; 
         FIG. 22  is a schematic illustration of the second embodiment of the present invention, showing how the ADU is opened when the apparatus is maintained; 
         FIG. 23  is a schematic illustration of the second embodiment of the present invention, showing how the TRU is opened when the apparatus is maintained; 
         FIG. 24  is a schematic lateral view of the lower frame, the front bracket and the rear bracket when the ADU is opened by 90 degrees according to the second embodiment of the present invention, showing partly as a see through view; 
         FIG. 25  is a schematic lateral view of a modified embodiment of the present invention, showing the front bracket and the rear bracket holding the front pin and the rear pin at the first hole section; and 
         FIG. 26  is a schematic lateral view of a modified embodiment of the present invention, showing the front bracket and the rear bracket holding the front pin and the rear pin at the second hole section. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Firstly, the first embodiment of the invention will be described in greater detail by referring to the accompanying drawings.  FIG. 1  is a schematic front view of image forming apparatus according to the first embodiment of the invention, which is a color copying machine of a four-series tandem system.  FIG. 2  is a schematic illustration of the color copying machine  1 , showing the configuration thereof. Referring to  FIGS. 1 and 2 , the color copying machine  1  comprises a scanner section  2  and an intra-body sheet ejecting section  3 . The color copying machine  1  also comprises four image forming units  11 Y,  11 M,  11 C and  11 K for four colors of yellow (Y), magenta (M), cyan (C) and black (K). The four image forming units  11 Y,  11 M,  11 C and  11 K are arranged in parallel relative to each other along and under the intermediate transfer belt  10 . 
     The image forming units  11 Y,  11 M,  11 C and  11 K respectively include photosensitive drums  12 Y,  12 M,  12 C and  12 K. Electric chargers  13 Y,  13 M,  13 C and  13 K, development apparatus  18 Y,  18 M,  18 C and  18 K, and photosensitive member cleaning apparatus  21 Y,  21 M,  21 C and  21 K are arranged respectively around the photosensitive drums  12 Y,  12 M,  12 C and  12 K in the direction of rotation thereof indicated by arrows t. The photosensitive drums  12 Y,  12 M,  12 C and  12 K are exposed respectively to laser beams emitted from a laser exposure apparatus  16  in zones from the electric chargers  13 Y,  13 M,  13 C and  13 K to the development apparatus  18 Y,  18 M,  18 C and  18 K. 
     For example the electric chargers  13 Y,  13 M,  13 C and  13 K electrically uniformly charge the entire surfaces of the respective photosensitive drums  12 Y,  12 M,  12 C and  12 K typically to about −700V. The development apparatus  18 Y,  18 M,  18 C and  18 K supply the photosensitive drums  12 Y,  12 M,  12 C and  12 K with respective two component developers each comprising a toner (of yellow (Y), magenta (M), cyan (C), or black (K)) and a carrier by means of respective development rollers to which a development bias voltage of e.g., about −500V is applied. 
     The laser exposure apparatus  16  emits laser beams from its semiconductor laser element to scan the respective photosensitive drums  12 Y,  12 M,  12 C and  12 K in the axial directions of the photosensitive drums by means of a polygon mirror  16   a , focusing the laser beams on the photosensitive drums  12 BK,  12 Y,  12 M and  12 C by way of a focusing lens system  16   b  and respective mirrors  44 . 
     The intermediate transfer belt  10  is made of, e.g., electrically semi-conductive polyimide that is a stable material from the viewpoint of thermal resistance and abrasion resistance. The intermediate transfer belt  10  is wound around a drive roller  22 , a follower roller  24  and a tension roller  23 . Primary transfer voltages are applied to the intermediate transfer belt  10  respectively at the positions located vis-à-vis the photosensitive drums  12 BK,  12 Y,  12 M and  12 C by means of primary transfer rollers  20 Y,  20 M,  20 C and  20 K so that the toner images on the photosensitive drums  12 Y,  12 M,  12 C and  12 K are sequentially transferred onto the intermediate transfer belt  10 . The photosensitive member cleaning apparatus  21 Y,  21 M,  21 C and  21 K recover the residual toners on the photosensitive drums  12 Y,  12 M,  12 C and  12 K as waste toner after the primary transfer. 
     A secondary transfer roller  26  is arranged to face the intermediate transfer belt  10  at secondary transfer position as an image transfer position where the intermediate transfer belt  10  is supported by the drive roller  22 . A sheet of paper P that is a transfer medium is fed to the secondary transfer position from either of first and second sheet feeding cassettes  27 ,  28  as a transfer medium feeding section respectively. More specifically, the sheet of paper P is taken out from the sheet feeding cassette  27  or  28 , which is a sheet feeding section, to first or second pickup roller  27   a  or  28   a , whichever appropriate. Then, the sheet of paper P is fed to the resist rollers  33   a ,  33   b  by way of first or second separation roller  27   b  or  28   b  and first or second conveyance roller  31  or  32 , whichever appropriate. The sheet of paper P is fed to the second transfer position in synchronism with the toner image on the intermediate transfer belt  10  by the resist rollers  33   a ,  33   b.    
     For example a secondary transfer voltage of about +1,000V is applied to the intermediate transfer belt  10  from the secondary transfer roller  26  at the secondary transfer position by way of the sheet of paper P. Then, as a result, the toner image on the intermediate transfer belt  10  is transferred onto the sheet of paper P for secondary transfer. A belt cleaner  10   a  is arranged at a position downstream relative to the secondary transfer roller  26  of the intermediate transfer belt  10 . The belt cleaner  10   a  recovers the toner remaining on the intermediate transfer belt  10  after the secondary transfer as waste toner. 
     The color copying machine  1  also comprises a manual feed tray  30  that is a sheet feeding section for feeding a sheet of paper P by manual. A manual feed pickup roller  30   a  and a manual feed separation roller  36  for separating the uppermost sheet of paper P and feeding it are arranged between the manual feed tray  30  and the resist rollers  33   a ,  33   b.    
     The sheet of paper P that is taken out from the sheet feeding cassette  27  or  28  or the manual feed tray  30  is then fed along longitudinal conveyance route  37  to fixing apparatus  38  by way of the resist rollers  33   a ,  33   b  and the secondary transfer roller  26 . The fixing apparatus  38  fixes the toner image transferred onto the sheet of paper P at the secondary transfer position by means of a heat and press process. A delivery conveyance route  41  and an ejecting roller  3   a  for ejecting the sheet of paper P to the ejecting section  3  are arranged downstream relative to the fixing apparatus  38 . The ejecting roller  3   a  can be driven to rotate both forwardly and backwardly. 
     An automatic duplex unit (to be referred to as ADU hereinafter)  45  as a re-conveyance mechanism is arranged at a lateral side  1   a  of the main body of the color copying machine  1 . The ADU  45  feed the sheet of paper P bearing a toner image at least on one of the opposite surfaces thereof that is fixed at the fixing apparatus  38  feed to the position of the secondary transfer roller  26  once again. A reversal area  40  is arranged above the fixing apparatus  38 . The sheet of paper P that bears a toner image fixed at the fixing apparatus  38  is reversed in the reversal area  40  and then feed back toward the ADU  45  by the ejecting roller  3   a  that can be driven to forwardly and then backwardly. 
     The ADU  45  is held by a lateral side cover  50  that can be turned relative to the lateral side  1   a  of the apparatus main body so as to be opened and closed. The ADU  45  has a reverse conveyance guide  46  and a re-conveyance roller  47  for feeding the sheet of paper P toward the secondary transfer roller  26 . 
     A secondary transfer unit (to be referred to as TRU hereinafter)  60  that is a conveyance mechanism is arranged at a position adjacent to the ADU  45  in the color copying machine  1 . The TRU  60  includes the secondary transfer roller  26 , the resist rollers  33   a ,  33   b , the secondary conveyance roller  32 , which are described above, and a conveyance guide  162  for feeding the sheet of paper P toward the secondary transfer roller  26 , all of which are held to a frame  161 . The frame  161  is adapted to be turned around a lower part thereof that operates as fulcrum so as to open and close the lateral side  1   a  of the apparatus main body. 
     Now, the opening/closing mechanism of the lateral side cover  50  will be described below.  FIG. 3  schematically illustrates the lateral side cover  50  and the structure of the support section arranged in the apparatus main body of the color copying machine  1  to support the lateral side cover  50 . Referring to  FIG. 3 , stationary side plates  61   a ,  61   b  are rigidly secured to the apparatus main body. The lateral side cover  50  includes movable side support plates  51   a ,  51   b  to be engaged respectively with the stationary side plates  61   a , and  61   b . Note that the profiles of the movable side support plates  51   a ,  51   b  and the stationary side plates  61   a ,  61   b  are simplified in  FIG. 3 . 
       FIG. 4  shows schematic plan views of one of the stationary side plates, or the stationary side plate  61   a  and the corresponding one of the movable side support plates, or the movable side support plate  51   a , as viewed in the respective directions indicated by arrows A 1  and A 2  in  FIG. 3 . 
     The movable side support plates  51   a ,  51   b  respectively include first hole sections  52   a ,  52   b  that operate as first fulcrums and second engaging pins  53   a ,  53   b . The two movable side support plates  51   a ,  51   b  are structurally identical and the second engaging pins  53   a ,  53   b  are located on a straight line running in parallel with the Y-axis in  FIG. 3 . So are the first hole sections  52   a ,  52   b.    
     The stationary side plates  61   a ,  61   b  respectively include first engaging pins  62   a ,  62   b , second hole sections  63   a ,  63   b  that operate as second fulcrums and third hole sections  64   a ,  64   b . The first engaging pin  62   a  is provided with a threaded hole  65 . Note that the first engaging pin  62   b  is not provided with any threaded hole. Otherwise, the two stationary side plates  61   a ,  61   b  are structurally identical. The first engaging pins  62   a ,  62   b  are located on a straight line running in parallel with the Y-axis in  FIG. 3 . So are the second hold sections  63   a ,  63   b  and the third hole sections  64   a ,  64   b.    
     The stationary side plates  61   a ,  61   b  respectively include walls sections that are orthogonally bent to the direction of the Y-axis. The wall sections are provided at those areas with respective concave portions  67   a ,  67   b . When the lateral side cover  50  is turned and inclined, the concave portions  67   a ,  67   b  are engaged respectively with the movable side support plates  51   a ,  51   b  to support the lateral side cover  50 . 
     Referring to  FIG. 3 , as the lateral side cover  50  is driven to slide in the Y-direction so as to put the first engaging pins  62   a ,  62   b  respectively into the first hole sections  52   a ,  52   b , the second engaging pins  53   a ,  53   b  are also put into the third hole sections  64   a ,  64   b  respectively. 
     Then, a screw  66  as a latch is driven into the threaded hole  65  as shown in  FIG. 4  while the movable side support plate  51   a  is located closer to the stationary side plate  61   a  than the threaded hole  65  of the first engaging pin  62   a  in the Y-direction, the lateral side cover  50  is blocked by the screw  66  and prevented from sliding in the Y-direction. Thus, the lateral side cover  50  is stably operated for opening/closing around the first engaging pins  62   a ,  62   b  that operate as spindles due to the first hole sections  52   a ,  52   b  operating as fulcrums. 
     The third hole sections  64   a ,  64   b  respectively guide the second engaging pins  53   a ,  53   b  along the trajectories of movement when the lateral side cover  50  is turned while the first engaging pins  62   a ,  62   b  are put into the first hole sections  52   a ,  52   b  respectively. For this reason, the third hole sections  64   a ,  64   b  shows an arc-shaped contour. 
     Now the operation of the above-described arrangement will be described below. When the color copying machine  1  is operated normally and a jam arises on the longitudinal conveyance route  37 , the lateral side cover  50  has to be opened in order to open the cover that holds the secondary transfer roller  26  and the resist roller  33   a.    
       FIG. 5  is a schematic plan view of front view of the first embodiment of the invention, showing how the lateral side cover  50  is opened and closed relative to the lateral side  1   a  of the apparatus main body in order to dissolve a jam. Like  FIG. 4 ,  FIG. 6  is schematic plan views of one of the stationary side plates, or the stationary side plate  61   a , and the corresponding one of the movable side support plates, or the movable side support plate  51   a , when a jam is to be dissolved. As the lateral side cover  50  is opened, the second engaging pins  53   a ,  53   b  remain engaged at the upper ends of the third hole sections  64   a ,  64   b  respectively. The movable side support plates  51   a    51   b  are engaged respectively with the concave portions  67   a ,  67   b . As a result, the lateral side cover  50  cannot be inclined beyond a first angle, which is a predetermined opening/closing angle θ 1 . The opening/closing angle θ 1  may be typically between 45° and 55°. 
     The operation of the above-described arrangement will be described below in terms of maintenance the inside of the color copying machine  1 . The lateral side cover  50  has to be opened wider to allow access to the inside of the color copying machine  1  when the inside of the color copying machine  1  is maintained than when a jam needs to be dissolved in the inside. For example, an opening angle θ 2  of the lateral side cover  50  may have to be opened to a second angle, which is 90°, to allow an operator to access the inside of the color copying machine  1  from the lateral side for maintenance.  FIG. 7  is a schematic front view of the color copying machine  1 , showing the opening angle  82  of the lateral side cover  50  is opened by 90° relative to the lateral side  1   a  of the color copying machine  1 . Like  FIG. 4 ,  FIG. 8  shows schematic plan views of one of the stationary side plates, or the stationary side plate  61   a , and the corresponding one of the movable side support plates, or the movable side support plate  51   a , when the apparatus is maintained. 
     When the screw  66  is not driven into the threaded hole  65  of the first engaging pin  62   a , the first engaging pins  62   a ,  62   b  can be disengaged respectively from the first hole sections  52   a    52   b  while the second engaging pins  53   a ,  53   b  can be disengaged respectively from the third hold sections  64   a ,  64   b  by sliding the lateral side cover  50  in the Y-direction. Therefore, when maintain the inside of the color copying machine  1 , the maintenance operator firstly takes out the screw  66 , in a state shown in  FIGS. 5 and 6 . Then, the operator disengages the lateral side cover  50  from the stationary side plates  61   a ,  61   b , while holding the lateral side cover  50  manually. 
     Subsequently, the operator puts the second engaging pins  53   a ,  53   b  respectively into the second hole sections  63   a ,  63   b  to bring the lateral side cover  50  into engagement with the stationary side plates  61   a ,  61   b  as shown in  FIGS. 7 and 8 . Thereafter, the operator turns the lateral side cover  50  to further open it until it takes a horizontal position. The lateral side cover  50  is turned around the second engaging pins  53   a ,  53   b  that operate as spindles due to the second hole sections  63   a ,  63   b  operating as fulcrums until it takes a horizontal position. The lateral side cover  50  keeps its horizontal attitude as the movable side support plate  51   a ,  51   b  are respectively engaged with the concave portions  67   a ,  67   b  formed on the stationary side plates  61   a ,  61   b . Note that the movable side support plates  51   a ,  51   b  do not contact with the first engaging pins  62   a ,  62   b  due to the structure when the lateral side cover  50  is turned while the second engaging pins  53   a ,  53   b  are respectively put into the second hole sections  63   a ,  63   b.    
     Thus, with the above-described first embodiment, it is possible to open wide the lateral side cover  50  relative to the lateral side  1   a  of the apparatus main body, by taking out the screw  66  from the first engaging pin  62   a , sliding the movable side support plates  51   a ,  51   b  in the Y-direction, disengaging the first engaging pins  62   a ,  62   b  respectively from the first hole sections  52   a ,  52   b  and then putting the second engaging pins  53   a ,  53   b  respectively into the second hole sections  63   a ,  63   b . Then, the operator can easily access the inside of the color copying machine  1  from the lateral side  1   a  of the apparatus main body. 
     After the maintenance operation, the state of  FIG. 4  is restored by reversely following the above-described sequence. More specifically, the operator turns the lateral side cover  50  by a predetermined angle and drives the movable side support plates  51   a ,  51   b  to slide in the Y-direction in order to move them away from the respective stationary side plates  61   a ,  61   a . Then, as a result, the second engaging pins  53   a ,  53   b  come off from the respective second hole sections  63   a ,  63   b . Then, the operator puts the first engaging pins  62   a ,  62   b  respectively into the first hole sections  52   a ,  52   b  and also the second engaging pins  53   a ,  53   b  respectively into the third hole sections  64   a ,  64   b . Additionally, the operator brings the movable side support plates  51   a ,  51   b  closer to the respective stationary side plates  61   a ,  61   b  and drives the screw  66  into the threaded hole  65  of the first engaging pin  62   a . Thereafter, the operator closes the lateral side cover  50 . As a result, the state of  FIG. 4  is restored. 
     With the above-described first embodiment, when a jam arises in the inside of the color copying machine  1  in an ordinary operation, the opening/closing angle of the ADU  45  can be held to the minimal level required to dissolve the jam. When, on the other hand, the color copying machine  1  has to be maintained, the operator can open wide and close the lateral side cover  50  relative to the lateral side  1   a  of the apparatus main body by rearranging the lateral side cover  50  relative to the apparatus main body so as to shift the fulcrums. The rearranging operation is simple and easy. Then, the inside of the color copying machine  1  can be accessed with ease from the lateral side  1   a  of the apparatus main body to improve the efficiency of maintenance. 
     Now, the second embodiment of the present invention will be described below. The second embodiment differs from the first embodiment in terms of the mode of moving the ADU unit. Otherwise, the two embodiments are same and identical. Therefore, the components of the second embodiment those are same as their counterparts of the first embodiment are denoted respectively by the same reference symbols and will not be described any further. As shown in  FIGS. 9 ,  10  and  11 , the lateral side cover  50  of the ADU  45  of the second embodiment is supported by a front bracket  70  and a rear bracket  71  that are support mechanisms arranged at the lateral side  1   a  of the apparatus main body so that it can be opened and closed relative to the apparatus main body. 
     As shown in  FIG. 12 , a front pin  152  and a rear pin  153  are formed as spindles at opposite sides of lower frame  151  of the lateral side cover  50 . The front bracket  70  and the rear bracket  71  are provided respectively with front pin supporting hole  72  and a rear pin supporting hole  73 . 
     The lower frame  151  is provided at the opposite sides thereof respectively with concave portions  151   a  adapted to be hit by stopper  70   a  of the front bracket  70  and the stopper  71   a  of the rear bracket  71  to prevent the ADU  45  from turning further. 
     As shown in  FIG. 13 , both the front pin supporting hole  72  and the rear pin supporting hole  73  have a first hole section  76  that operates as the first fulcrum and the first bearing, a second hole section  77  that operates as the second fulcrum and the second bearing and a slit section  78  as a link section that links the first hole section  76  and the second hole section  77 . Both the front pin  152  and the rear pin  53  having a cylindrical profile are cut at opposite sides  154 ,  155 . In other words, both the front pin  152  and the rear pin  153  show an oval cross-section so as to operate as cams. 
     As shown in  FIG. 14 , the front pin  152  and the rear pin  153  are respectively put into the front pin supporting hole  72  and the rear pin supporting hole  73 . When the front pin  152  and the rear pin  153  are supported in the respective first hole sections  76 , the lateral side cover  50 , or the ADU  45 , can be opened and closed by an angle of e.g., 50° as the first angle, relative to the lateral side  1   a  of the apparatus main body. When, on the other hand, the front pin  152  and the rear pin  153  are supported in the respective second hole sections  77 , the ADU  45  can be opened and closed by an angle of e.g., 90° as the second angle, relative to the lateral side  1   a  of the apparatus main body. 
     The slit sections  78  respectively support the front pin  152  and the rear pin  153  so as to allow them slide there when their cut opposite sides  154 ,  155  run in parallel with the slit sections  78 . For example, when ADU  45  is opened by an angle of 35°, the cut opposite sides  154 ,  155  of the front pin  152  and those of the rear pin  153  of the ADU  45  run in parallel with the slit sections  78 . Then, the front pin  152  and the rear pin  153  can be put into the respective slit sections  78 . 
     The frame  161  of the TRU  60  is also supported by the front bracket  70  and the rear bracket  71  so that it may be turned around them to become opened and closed. As shown in  FIG. 15 , the pins  161   a  arranged at lower lateral sides of the frame  161  are respectively rotatably put into the TRU supporting hole  79  of the front bracket  70  and the TRU supporting hole  79  of the rear bracket  71 . The opening angle of the TRU  60  is limited as it interferes with the ADU  45 . 
     Now, the operation of the second embodiment will be described below. When an image forming process is executed in the color copying machine  1 , the front pin  152  and the rear pin  153  of the ADU  45  are supported in the respective first hole sections  76 . When the ADU  45  is closed relative to the lateral side  1   a  of the apparatus main body, the concave portions  151   a  of the lower frame  151  of the lateral side cover  50  are separated respectively from the stopper  70   a  of the front bracket  70  and the stopper  71   a  of the rear bracket  71  as shown in  FIG. 16 . 
     When a jam arises on the longitudinal conveyance route  37  in this condition, the ADU  45  needs to be turned to turn the TRU  60  in order to dissolve the jam as shown in  FIGS. 17 ,  18  and  19 . Firstly, the ADU  45  is turned around the front pin  152  and the rear pin  153 , which operate as spindles, using the first hole sections  76  as fulcrums, in the direction of arrow f. Then, as the ADU  45  is opened by a turning angle of 50° from the lateral side  1   a  of the apparatus main body as shown in  FIG. 19 , the concave portions  151   a  of the lower frame  151  of the lateral side cover  50  respectively contact the stopper  70   a  of the front bracket  70  and the stopper  71   a  of the rear bracket  71 . As a result, the ADU  45  stops turning. 
     Thereafter, the TRU  60  is turned in the direction of arrow f. More specifically, the TRU  60  is turned around the pins  161   a  that operate as spindles, using the TRU supporting holes  79  as fulcrums, by about 50° as in the case of the ADU  45 . Then, as a result, the frame  161  of the TRU  60  contacts the ADU  45  and the TRU  60  stops turning. Now, the operator can dissolve the jam that takes place in at the conveyance guide  162  or some other position of the longitudinal conveyance route  37  in this condition. After dissolving the jam, the operator turns the TRU  60  in the direction of arrow k to put it back in the main body of the color copying machine  1 . Thereafter, the operator turns the ADU  45  also in the direction of arrow k to close the lateral side  1   a  of the apparatus main body. Thus, the color copying machine  1  can reactivate the image forming process. Note that, when a jam takes place in the ADU  45 , it can be dissolved only by opening the ADU  45 . 
     When the inside of the color copying machine  1  is to be maintained, the ADU  45  and the TRU  60  are turned to a larger extent than when a jam is dissolved to open wide the lateral side of the main body  1   a  of the image forming apparatus as shown in  FIGS. 22 ,  23  and  24 . Firstly, the ADU  45  is opened by an angle of 35° from the position where it runs in parallel with the lateral side  1   a  of the apparatus main body  1   a  in a condition where the front pin  152  and the rear pin  153  are put into the respective first hole sections  76 . As a result, the opposite sides  154 ,  155  of the front pin  152  and those of the rear pin  153  run in parallel with the slit sections  78 . Then, the front pin  152  and the rear pin  153  are put into the respective slit sections  78 . Thereafter, the front pin  152  and the rear pin  153  are driven to slide in the direction of arrow g in  FIG. 20  along the respective slit sections  78 , so as to be put into the second hole section  77  of the front pin  152  and that of the rear pin  152  respectively. 
     Subsequently, the ADU  45  is further turned around the front pin  152  and the rear pin  153 , which operate as spindles, using the second hole sections  77  as fulcrums in the direction of arrow f in  FIGS. 22 ,  23  and  24 , in order to open the lateral side  1   a  of the apparatus main body wider. As the ADU  45  is opened by a rotary angle of 90° from the lateral side  1   a  of the apparatus main body, the concave portions  151   a  of the lower frame  151  respectively hit the stopper  70   a  of the front bracket  70  and the stopper  71   a  of the rear bracket  71 . As a result, the ADU  45  stops turning. Since the fulcrums for opening/closing the ADU  45  are the second hole sections  77  located at higher positions, the ADU  45  is prevented from interfering with the manual feed tray  30 . 
     Then, the TRU  60  is turned around the pins  161   a , which operate as spindles, using the TRU supporting holes  79  as fulcrums in the direction of arrow f. As the TRU  60  is turned by about 70° from the lateral side  1   a  of the apparatus main body as shown in  FIG. 23 , the frame  161  touches the ADU unit  45  so that the latter stops turning. As a result, the lateral side  1   a  of the apparatus main body is opened wide. Subsequently, the intermediate transfer belt  10  in the color copying machine  1  is driven to slide in the direction of arrow h and taken out from the lateral side  1   a  of the apparatus main body for maintenance. If necessary, each of the image forming units  11 Y,  11 M,  11 C and  11 BK may be taken out from the lateral side  1   a  of the apparatus main body for maintenance. 
     After the completion of the maintenance operation, the TRU  60  is turned in the direction of arrow k and put back into the main body of the color copying machine  1 . Then, the ADU  45  is turned in the direction of arrow k and put back to the position with a rotary angle of 35° from the lateral side  1   a  of the apparatus main body. The front pin  152  and the rear pin  153  are put into the respective slit sections  78  at this position. Then, front pin  152  and the rear pin  153  are driven to slide in the respective slit sections  78  in the direction of arrow i in  FIG. 21  until the front pin  152  and the rear pin  153  are respectively put into the first hole sections  76 . 
     Thereafter, the ADU  45  is turned further, using the first holes  76  as fulcrums, in the direction of arrow k to close the lateral side  1   a  of the apparatus main body. As a result, the color copying machine  1  is ready for a new image forming process. 
     When dissolving a jam in the above-described second embodiment, the ADU  45  is opened by a rotary angle of 50°, using the first hole sections  76  as fulcrums, so that consequently the TRU  60  can be opened also by a rotary angle of 50°. When, on the other hand, maintenance the inside of the color copying machine  1 , the ADU  45  is opened by a rotary angle of 90°, using the second hole sections  77  as fulcrums, so that consequently the TRU  60  can be opened also by a rotary angel of 70°. Therefore, a small working space is provided to dissolve a jam. Then, it is possible to save space when installing the color copying machine  1  and increase the degree of freedom of installing the color copying machine  1  in terms of the position for installing it. When maintenance the inside of the color copying machine  1 , the lateral side  1   a  of the apparatus main body is opened wide so that the intermediate transfer belt  10  and other components in the inside of the color copying machine  1  can be taken out from the lateral side  1   a  of the apparatus main body. In other words, it is possible to increase the degree of freedom of maintenance the color copying machine. 
     The fulcrums for turning the ADU  45  can be moved from the first hole sections  76  to the second hole sections  77  with ease only by driving the front pin  152  and the rear pin  153  to slide in the respective slit sections  78 . Therefore, it is no longer necessary to take out the ADU  45  from the lateral side  1   a  of the apparatus main body and temporarily put it somewhere near the apparatus main body for the purpose of maintenance the inside of the color copying machine  1 . Thus, the maintenance efficiency will be remarkably improved. 
     The present invention is by no means limited to the above-described embodiments, which may be modified and altered in various different ways without departing from the spirit and scope of the present invention. For example, the angle of opening the re-conveyance mechanism is not limited to those described above. The first angle may be appropriately selected to conveniently dissolve jams. The second angle may also be appropriately selected to conveniently take out the intermediate transfer belt and other components from the inside of the apparatus main body for maintenance. The profile of the spindles of the re-conveyance mechanism may be appropriately defined so long as the re-conveyance mechanism can be turned smoothly at the first bearings and the second bearings and the spindles can be driven to slide along the respective link sections. 
     Additionally, the support mechanisms for supporting the spindles of the re-conveyance mechanism are not limited to those described above particularly in terms of profile and structure. For example, those of the second embodiment may be modified and fulcrum supporting springs  80  may be provided respectively in the front pin supporting hole  72  and the rear pin supporting hole  73  that are formed at the front bracket  70  and the rear bracket  71 . Such fulcrum supporting springs  80  operate to reliably hold the front pin  152  and the rear pin  153  in the first hole sections  76  respectively as shown in  FIG. 25 . Such fulcrum supporting springs  80  also operate to reliably hold the front pin  152  and the rear pin  153  in the second hole sections  77  respectively as shown in  FIG. 26 . Then, as a result, it is possible to improve the safety of operation when opening/closing the re-conveyance mechanism.