Abstract:
An image forming apparatus includes plural image holders that hold an image; plural development devices that produce an image on the plural image holders; an intermediate transfer body supported by plural support members; plural first transfer devices that transfer images that are present on the plural image holders to the intermediate transfer body; a second transfer device that transfers a composite image from the intermediate transfer body onto a recording medium; a fixing device that fixes the composite image onto the recording medium; an ejection device that ejects the recording medium having the composite image transferred thereto out of the image forming apparatus main body; and a recording medium stacking part where ejected recording media are stacked.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application Nos. 2009-042286 filed Feb. 25, 2009 and 2009-042287 filed Feb. 25, 2009. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to image forming apparatus. 
         [0004]    2. Summary 
         [0005]    According to an aspect of the invention, there is provided an image forming apparatus including plural image holders that hold an image respectively; plural development devices that produce an image on the plural image holders respectively; an intermediate transfer body supported by plural support members; plural first transfer devices that respectively transfer images which are respectively present on the plural image holders in turn and overlayingly onto the intermediate transfer body; a second transfer device that transfers a composite transferred image from the intermediate transfer body onto a recording medium; a fixing device that fixes the composite image onto the recording medium by applying heat and pressure to the recording medium having the composite image transferred thereto; an ejection device that ejects the recording medium having the composite image fixed thereto out of the image forming apparatus main body; and a recoding medium stacking part where ejected recording media are stacked, the plural image holders being arranged along an under side of the intermediate transfer body, the apparatus further including a first power supply unit located beneath the plural image holders and a second power supply unit located above the intermediate transfer body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0007]      FIG. 1  is a perspective view showing an image forming apparatus in accordance with a first exemplary embodiment of the invention; 
           [0008]      FIG. 2  is a cross-sectional view of the image forming apparatus shown in  FIG. 1 ; 
           [0009]      FIG. 3  is a side view of the apparatus, illustrating how a main opening/closing part is opened/closed with respect to the main body of the image forming apparatus shown in  FIG. 1  and how photoreceptor units are installed in and removed from the main body; 
           [0010]      FIG. 4  is a cross-sectional view of a photoreceptor unit employed in the image forming apparatus shown in  FIG. 1 ; 
           [0011]      FIGS. 5A and 5B  illustrate movement of a shutter member included in the photoreceptor unit shown in  FIG. 4 , wherein  FIG. 5A  is a cross-sectional view in which the shutter member lies in a second position and  FIG. 5B  is a cross-sectional view in which the shutter member lies in a first position; 
           [0012]      FIG. 6  is a cross-sectional view of a developer remover employed in the image forming apparatus shown in  FIG. 1 ; 
           [0013]      FIG. 7  is a perspective view of a belt unit employed in the image forming apparatus shown in  FIG. 1 ; 
           [0014]      FIG. 8  is a cross-sectional view of a second power supply unit employed in the image forming apparatus shown in  FIG. 1 ; 
           [0015]      FIG. 9  is a block diagram illustrating power feeding in the image forming apparatus shown in  FIG. 1 ; 
           [0016]      FIG. 10  is a perspective view showing an image forming apparatus in accordance with a second exemplary embodiment of the invention; 
           [0017]      FIG. 11  is a perspective view of a belt unit employed in the image forming apparatus shown in  FIG. 10 ; 
           [0018]      FIG. 12  is a cross-sectional view of a second power supply unit employed in the image forming apparatus shown in  FIG. 10 ; 
           [0019]      FIG. 13  is a first cross-sectional view of a protection member employed in the image forming apparatus shown in  FIG. 10 ; and 
           [0020]      FIG. 14  is a second cross-sectional view of the protection member employed in the image forming apparatus shown in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Exemplary embodiments of the present invention will now be described with reference to the drawings. 
         [0022]    An image forming apparatus  10  in accordance with a first exemplary embodiment of the invention is shown in  FIG. 1  and  FIG. 2 . As can be seen in  FIG. 1  and  FIG. 2 , the image forming apparatus  10  has an image forming apparatus main body  12 . 
         [0023]    A front opening/closing part  18  is hinged to the image forming apparatus main body  12  with hinges  20 , so that it can be opened and closed with respect to the apparatus main body  12 . Also, a main opening/closing part  26  is hinged to the image forming apparatus main body  12  with hinges  28 , so that it can be opened and closed with respect to the apparatus main body  12 . An operator panel  32  is mounted in the front of the image forming apparatus main body  12 . 
         [0024]    An area of the upper surface of the image forming apparatus  10 , for example, the upper surface of the main opening/closing part  26  is used as a paper output part  14  to which paper having an image formed thereon is ejected. 
         [0025]    An opening/closing part  22  for supply is mounted in the front opening/closing part  18 , so that the part  22  can be opened and closed. The opening/closing part  22  for supply is usually closed with respect to the front opening/closing part  18 , as shown in  FIG. 1  and  FIG. 2 . The opening/closing part  22  for supply is opened with respect to the front opening/closing part  18 , when the user wants to use sheets different from ones stored in a sheet feeder  510  which will be described later. 
         [0026]    The main opening/closing part  26  is usually closed with respect to the image forming apparatus main body  12 . The main opening/closing part  26  is opened for installing or removing at least one of photoreceptor units  200 Y,  200 M,  200 C,  200 B which will be described later in/from the image forming apparatus main body  12 . In order to prevent that a support roller  70 , an intermediate transfer belt  62 , etc., which will be described later, assembled in the main opening/closing part  26  interfere with the front opening/closing part  18 , the front opening/closing part  18  should be opened with respect to the image forming apparatus main body  12  before opening the main opening/closing part  26 . 
         [0027]    When closing the front opening/closing part  18  with respect to the image forming apparatus main body  12 , the main opening/closing part  26  should be closed with respect to the image forming apparatus main body  12  before closing the front opening/closing part  18 . The upper surface of the main opening/closing part  26  is used as the paper output part to which sheets having an image formed thereon are ejected. 
         [0028]    A secondary opening/closing part  30  is assembled in the main opening/closing part  26 , so that it can be opened and closed with respect to the main opening/closing part  26 . The secondary opening/closing part  30  can be opened and closed independently of the main opening/closing part  26 ; it can be opened while the main opening/closing part  26  is closed with respect to the image forming apparatus main body  12 . The secondary opening/closing part  30  is opened for installing or removing the whole or a part of a developer remover  350  which will be described later in/from the image forming apparatus main body  12 . 
         [0029]    The operator panel  32  includes, for example, a numeric keypad which is used to enter the number of sheets which are subjected to image formation thereon, a start button which is pressed to start an image forming operation, and others. 
         [0030]    Inside the image forming apparatus main body  12 , an image forming part  40  is provided that forms an image on a sheet. The image forming part  40  includes, for example, four photoreceptor units  200 Y,  200 M,  200 C,  200 K. 
         [0031]    The photoreceptor units  200 Y,  200 M,  200 C,  200 K are respectively used as image forming structures and, respectively, have photoreceptor drums  210 Y,  210 M,  210 C,  210 K, each of which can be separately installed and removed in/from the image forming apparatus main body  12 . The photoreceptor units  200 Y,  200 M,  200 C,  200 K are arranged in the order of a photoreceptor unit  200 Y which is the first one, a second unit  200 M, a third unit  200 C, and the last unit  200 K from the rear side (right side in  FIG. 2 ) of the image forming apparatus main body  12 . The photoreceptor units  200 Y,  200 M,  200 C,  200 K will be detailed later. 
         [0032]    The photoreceptor drums  210 Y,  210 M,  210 C,  210 K are used as image holders that hold an image respectively. 
         [0033]    The image forming part  40  also includes an optical projection device  44  which serves as a latent image forming device. The optical projection device  44  irradiates each of the photoreceptor drums  210 Y,  210 M,  210 C,  210 K with light and forms a latent image on the surface of each of the photoreceptor drums  210 Y,  210 M,  210 C,  210 K. 
         [0034]    The image forming part  40  also includes development devices  46 Y,  46 M,  46 C,  46 K. The development device  46 Y develops a latent image formed on the photoreceptor drum  210 Y with a yellow toner stored therein. The development device  46 M develops a latent image formed on the photoreceptor drum  210 M with a magenta toner stored therein. The development device  46 C develops a latent image formed on the photoreceptor drum  210 C with a cyan toner stored therein. The development device  46 K develops a latent image formed on the photoreceptor drum  210 K with a black toner stored therein. 
         [0035]    The image forming part  40  further includes a transfer device  58 . The transfer device  58  includes an intermediate transfer belt unit  60  and a second transfer device  84 . The intermediate transfer belt unit  60  includes an intermediate transfer belt  62 . 
         [0036]    The intermediate transfer belt  62  serves as an intermediate transfer body onto which images (toner images) are transferred from the photoreceptor drums  210 Y,  210 M,  210 C,  210 K. The intermediate transfer belt  62  is endless and lays across in a tensioned state on support rollers  64 ,  66 ,  68 ,  70 ,  72  so that it can rotate in a direction indicated by an arrow in  FIG. 2 . A driving force from a motor  90  (see  FIG. 7 ) is conveyed to a support roller  70  via a gear  92  (see  FIG. 7 ) which will be described later and, by its turning driven by the driving force from the motor  90 , the support roller  70  conveys the driving force to the intermediate transfer belt  62 . 
         [0037]    The intermediate transfer belt unit  60  also includes first transfer rollers  80 Y,  80 M,  80 C,  80 K which are used as a first transfer device. The first transfer rollers  80 Y,  80 M,  80 C,  80 K transfer yellow, magenta, cyan, and black toner images respectively formed on the photoreceptor drums  210 Y,  210 M,  210 C,  210 K to the intermediate transfer belt  62 . Additional description will be provided later for the intermediate transfer belt unit  60 . 
         [0038]    The second transfer device  84  includes a second transfer roller  86 . The second transfer roller  86  further transfers the yellow, magenta, cyan, and black toner images transferred to the intermediate transfer belt  62  onto a sheet. 
         [0039]    The transfer device  58  includes a developer remover  350 . The developer remover  350  includes a scraping member  354 . A part of the developer remover  350  can be installed and removed in/from the image forming apparatus main body  12  through an opening provided by opening the secondary opening/closing part  30 . The developer remover  350  will be detailed later. 
         [0040]    Among the members constituting the transfer device  58 , the intermediate transfer belt unit  60  and the developer remover  350  are assembled in the main opening/closing part  26 . Among the components of the transfer device  58 , the second transfer roller  86  is fixed to the image forming apparatus main body  12 . Moreover, the intermediate transfer belt  62  is disposed aslant such that its one end portion being in contact with the support roller  70 , adjacent to the second transfer device  84 , is positioned lower in the direction of gravitational force than its opposite end portion being in contact with the support roller  64 . 
         [0041]    Inside the image forming apparatus main body  12 , furthermore, a fixing device  50  is provided that fixes a composite toner image transferred to a sheet by the second transfer roller  86  onto the sheet. The fixing device  50  includes a heater  51 . The fixing device  50  fixes the composite developer image onto the sheet by pressing the developer image onto the sheet, while applying heat generated by the heater  51 . 
         [0042]    Inside the image forming apparatus main body  12 , a waste toner receiver  300  is also provided. Deteriorated waste developer particles expelled from the development devices  46 Y,  46 M,  46 C,  46 K are collected into the waste toner receiver  300 . The waste toner receiver  300  is, for example, integral with the photoreceptor unit  200 K. 
         [0043]    Inside the image forming apparatus main body  12 , a sheet feeder  510  is installed to feed a sheet to the image forming part  40 . The sheet feeder  510  can be pulled out from the front side (left side in  FIG. 2 ) of the image forming apparatus main body  12 , so that the sheet feeder  510  will be replenished with sheets after being pulled out of the image forming apparatus main body  12 . 
         [0044]    The sheet feeder  510  has a sheet container  512  which stocks a stack of sheets of, e.g., plain paper. The sheet feeder  510  includes a feed roller  514  which extracts a sheet at the top of the sheet stack stocked in the sheet container  512  and feeds the extracted sheet toward the image forming part  40 . The sheet feeder  510  also includes a retard roller  516  to retard sheets which is used to prevent plural sheets clinging together from being fed to the image forming part  40 . 
         [0045]    Moreover, a transport path  530  that is used to transport a sheet is formed inside the image forming apparatus main body  12 . The transport path  530  includes a main transport path  532 , a reverse transport path  534 , and a sub-transport path  536 . 
         [0046]    The main transport path  532  is used to transport a sheet fed from the sheet feeder  510  to the image forming part  40  and eject the sheet having an image formed thereon out of the image forming apparatus main body  12 . Along the main transport path  532 , the above-mentioned feed roller  514  and retard roller  516 , registration rollers  542 , the above-mentioned second transfer roller  86 , the above-mentioned fixing device  50 , and eject rollers  544  are disposed in the mentioned order from upstream in a direction in which a sheet is transported. 
         [0047]    The registration rollers  542  temporarily stop the forward edge of a sheet fed from the sheet feeder  510  and transport the sheet toward the second transfer roller  86  so that the sheet will enter the rollers, namely, the second transfer roller  86  and the support roller  70 , in time with timing when the toner images of each color have been transferred to the intermediate transfer belt  62 . 
         [0048]    The eject rollers  544  eject a sheet having the toners of each color fixed onto it by the fixing device  50  out of the image forming apparatus main body  12 . 
         [0049]    The reverse transport path  534  is a transport path which is used to turn over and supply again a sheet having a composite toner image fixed onto its one side toward the image forming part  40 . Along the reverse transport path  534 , for example, two pairs of reverse transport rollers  548  are disposed. In the reverse transport path  534 , once the rear edge of a sheet have been nipped between the eject rollers  544 , the sheet is supplied again, moved back by reverse rotation of the eject rollers  544 , i.e., its rear edge goes ahead, and the supplied sheet is transported by the reverse transport rollers  548  to a position upstream of the registration rollers  542 . 
         [0050]    The sub-transport path  536  is a transport path to supply a different sheet from the sheets stored in the sheet feeder  510  to the image forming part  40 . With the opening/closing part  22  for supply being open, a sheet is supplied to the sub-transport path  536  from the front side of the image forming apparatus main body  12 . Along the sub-transport path  536 , a transport roller  522  and a retard roller  554  are provided. The transport roller  522  transports a sheet supplied to the sub-transport path  536  toward the image forming part  40 . The retard roller  554  is used to retard sheets supplied to the sub-transport path  536  and prevent plural sheets clinging together from being transported to the image forming part  40 . 
         [0051]    Inside the image forming apparatus main body  12 , a first power supply unit  410  is further provided. The first power supply unit  410  includes a high-voltage power supply circuit and feeds power to, for example, the development devices  46 Y,  46 M,  46 C,  46 K. 
         [0052]    In the image forming apparatus  10 , furthermore, a second power supply unit  420  is located above the intermediate transfer belt  62 . The second power supply unit  420  is installed in the main opening/closing part  26  and feeds power to, for example, the first transfer rollers  80 Y,  80 M,  80 C,  80 K, among others. 
         [0053]    As can be seen in  FIG. 2 , in the image forming apparatus  10 , the intermediate transfer belt  62  is located over the photoreceptor drums  210 Y,  210 M,  210 C,  210 K. In the image forming apparatus  10 , the first power supply unit  410  is located beneath the photoreceptor drums  210 Y,  210 M,  210 C,  210 K. Furthermore, in the image forming apparatus  10 , the second power supply unit  420  is located above the intermediate transfer belt  62 . 
         [0054]    Furthermore, in the image forming apparatus  10 , the optical projection device  44  is located beneath the photoreceptor drums  210 Y,  210 M,  210 C,  210 K and the first power supply unit  410  is located beneath the optical projection device  44 . Furthermore, in the image forming apparatus  10 , the paper output part  14  is located above the intermediate transfer belt  62  and the second power supply unit  420  is located in a space provided between the intermediate transfer belt  62  and the paper output part  14 . 
         [0055]    Furthermore, in the image forming apparatus  10 , the developer remover  350  and the fixing device  50  are located near outside the opposite long lateral walls of the second power supply unit  420 . 
         [0056]      FIG. 3  illustrates how the main opening/closing part  26  is opened/closed with respect to the image forming apparatus main body  12  and how the photoreceptor units  200  are installed in and removed from the image forming apparatus main body  12 . 
         [0057]    As shown in  FIG. 3 , when the main opening/closing part  26  is opened with respect to the image forming apparatus main body  12 , the intermediate transfer belt unit  60  and the developer remover  350  in the transfer device  58  as well as the second power supply unit  420  are displaced together with the main opening/closing part  26 . That is, the intermediate transfer belt unit  60 , the developer remover  350 , and the second power supply unit  420  are opened and closed as an assembly in the main opening/closing part  26  with respect to the image forming apparatus main body  12 . 
         [0058]    When the main opening/closing part  26 , the intermediate transfer belt unit  60 , the developer remover  350 , and the second power supply unit  420  are opened with respect to the image forming apparatus main body  12 , an open space  36  is provided in the image forming apparatus main body  12 . Through the open space  36 , each of the photoreceptor units  200 Y,  200 M,  200 C,  200 K is installed in and removed from the image forming apparatus main body  12 . The waste toner receiver  300  is integral with the photoreceptor unit  200 K, as already mentioned. Therefore, the waste toner receiver  300  is installed and removed integrally with the photoreceptor unit  200 K in/from the image forming apparatus main body  12 . 
         [0059]    A photoreceptor unit  200 Y is shown in  FIG. 4 . Since the photoreceptor units  200 M,  200 C,  200 K have the same structure as the photoreceptor unit  200 Y, though they use developers of different colors, their descriptions are omitted. 
         [0060]    As shown in  FIG. 4 , the photoreceptor unit  200 Y has a photoreceptor unit main body  202 Y and the above-mentioned photoreceptor drum  210 Y is installed in the photoreceptor unit main body  202 Y. A part of the photoreceptor drum  210 Y is exposed outside the photoreceptor unit main body  202 Y as an exposed portion  212 Y. The photoreceptor unit main body  202 Y serves as a housing in which the photoreceptor drum  210 Y is installed with a part of the drum being exposed. 
         [0061]    Inside the photoreceptor unit main body  202 Y, a charging device  220 Y which evenly charges the surface of the photoreceptor drum  210 Y is installed. The charging device  220 Y includes a charging roller  222 Y contacting with the photoreceptor drum  210 Y. Onto the surface of the photoreceptor drum  210 Y evenly charged by the charging device  220 Y evenly, a latent image is projected by the optical projection device  44  (see  FIG. 1 ). 
         [0062]    Inside the photoreceptor unit main body  202 Y, further, a scraping member  224 Y which serves as a cleaning device is installed. The scraping member  224 Y scrapes off yellow toner particles remaining on the surface of the photoreceptor drum  210 Y after a yellow toner image has been transferred to the intermediate transfer belt  62  by the first transfer roller  80 Y (see  FIG. 1 ). 
         [0063]    Inside the photoreceptor unit main body  202 Y, there is also a waste toner chamber  226 Y where yellow toner particles scraped off by the scraping member  224 Y from the surface of the photoreceptor drum  210 Y are collected. 
         [0064]    In the photoreceptor unit main body  202 Y, further, a shutter member  230 Y is installed via, e.g., a support member  232 Y. The shutter member  230 Y serves as a moving member. The shutter member  230 Y is also connected to a linkage mechanism  404  and the shutter member  230 Y is connected via the linkage mechanism  404  to the above-mentioned intermediate transfer belt unit  60 . 
         [0065]    Movement of the shutter member  230 Y is illustrated in  FIGS. 5A and 5B . The shutter member  230 Y moves between a position shown in  FIG. 5A  which is used as a second position and a position shown in  FIG. 5B  which is used as a first position. 
         [0066]    The second position shown in  FIG. 5A  is the position in which the shutter member  230 Y covers the exposed portion  212 Y of photoreceptor drum  210 Y (hereinafter referred to as a covering position). The first position shown in  FIG. 5B  is the position in which the shutter member  230 Y leaves the exposed portion  212 Y exposed out of the photoreceptor unit main body  202  (hereinafter referred to as an exposure position). 
         [0067]    The shutter member  230 Y lies in the covering position shown in  FIG. 5A  in a state where the photoreceptor unit  200 Y is removed from the image forming apparatus main body  12 . The shutter member  230 Y still lies in the covering position shown in  FIG. 5A  in a state where the photoreceptor unit  200 Y is installed in the image forming apparatus main body  12 , but the intermediate transfer belt unit  60  is opened with respect to the image forming apparatus main body  12 . However, the shutter member  230 Y lies in the exposure position shown in  FIG. 5B  in a state where the photoreceptor unit  200 Y is installed in the image forming apparatus main body  12  and the intermediate transfer belt unit  60  is closed with respect to the image forming apparatus main body  12 . 
         [0068]    The shutter member  230 Y is connected to the intermediate transfer belt unit  60  by the above-mentioned linkage mechanism  404 . By the action of the linkage mechanism  404 , the shutter member  230 Y moves from the exposure position to the covering position in conjunction of an action making the intermediate transfer belt unit  60  open with respect to the image forming apparatus main body  12 . By the action of the linkage mechanism  404 , the shutter member  230 Y moves from the covering position to the exposure position in conjunction with an action making the intermediate transfer belt unit  60  closed with respect to the image forming apparatus main body  12 . 
         [0069]    The developer remover  350  is shown in  FIG. 6 . 
         [0070]    The developer remover  350  includes a developer remover main body  352  fixed to the main opening/closing part  26  (see  FIG. 1 ) and a receiving container  370  which can be installed in and removed from the developer remover main body  352 . The above-mentioned scraping member  354  is attached to the developer remover main body  352 . A through hole  356  for developer particles to pass through is provided in the developer remover main body  352 . An expelling member  358  is installed inside the developer remover main body  352 . 
         [0071]    The expelling member  358  rotates clockwise as indicated by an arrow in  FIG. 6  to expel developer particles scraped off the surface of the intermediate transfer belt  62  by the scraping member  354  to the receiving container  370  through the through hole  356 . Further, a fullness detecting sensor  360  which detects whether the receiving container  370  is full is installed in the developer remover main body  352 . 
         [0072]    Developer particles eliminated from the intermediate transfer belt  62  by the scraping member  354  and expelled by the expelling member  358  are accumulated in the receiving container  370 . A through hole  372  for developer particles expelled by the expelling member  358  to pass through is provided in the receiving container  370  in a position corresponding to the through hole  356 . Further, a developer expelling member  372  is installed inside the receiving container  370 . The developer expelling member  372  expels developer particles toward the fullness detecting sensor  360  by rotating clockwise as indicated in  FIG. 6 . 
         [0073]    The receiving container  370  is replaced when it becomes full. That is, when the receiving container  370  becomes full, the receiving container  370  should be removed from the developer remover main body  352  and taken out through an opening provided by opening the secondary opening/closing part  30  (see  FIG. 2 ) and, in turn, another receiving container  370  should be installed in the developer remover main body  352 . 
         [0074]    There is a possibility that developer particles accumulated in the receiving container  370  melt due to heat generated by, for example, the fixing device  50  (see  FIG. 1 ). If developer particles melt in the receiving container  370 , subsequently hardened developer after melting may bring the developer expelling member  372  to standstill, not rotating. In turn, the standstill of the developer expelling member  372  makes it impossible to receive further developer particles, for example, even if there remains some space for receiving them in the receiving container  370 . 
         [0075]    The intermediate transfer belt unit  60  is shown in  FIG. 7 . 
         [0076]    As can be seen in  FIG. 7 , the intermediate transfer belt unit  60  includes a right side plate  102 , a left side plate  104 , and a connecting member  106  which connects the right side plate  102  with the left side plate  104 . The right side plate  102 , the left side plate  104 , and the connecting member  106  are used as an intermediate transfer body supporting part which supports the intermediate transfer belt  62 . That is, the above-mentioned support rollers  64 ,  66 ,  68 ,  70 ,  72  (see  FIG. 1 ) are installed, their ends being fastened to the right side plate  102  and the left side plate  104 . The right side plate  102  and the left side plate  104  support the intermediate transfer belt  62  via the support rollers  64 ,  66 ,  68 ,  70 ,  72 . 
         [0077]    The right side plate  102  and the left side plate  104  also support the above-mentioned first transfer rollers  80 Y,  80 M,  80 C,  80 K (see  FIG. 1 ). 
         [0078]    The intermediate transfer belt unit  60  further includes a gear  92  placed on the shaft of the support roller  70  (see  FIG. 1 ). The driving force from the motor  90  which is used as the driving source is conveyed to the gear  92 , which in turn rotates the support roller  70 , so that the driving force is conveyed to the intermediate transfer belt  62 . 
         [0079]    The intermediate transfer belt unit  60  is also connected to the above-mentioned linkage mechanism  404  (see  FIG. 4 ). That is, the intermediate transfer belt unit  60  and each of the shutter members  230 Y,  230 M,  230 C,  230 K are connected via the linkage mechanism  404 . As described above, thus, the shutter members  230 Y,  230 M,  230 C,  230 K are opened and closed in conjunction with opening and closing of the intermediate transfer belt unit  60  with respect to the image forming apparatus main body  12 . 
         [0080]    The second power supply unit  420  is installed, its short sides being fastened to the right side plate  102  and the left side plate  104 . That is, both short sides of the power supply substrate  422  of the second power supply unit  420  are fastened to the right side plate  102  and the left side plate  104 . 
         [0081]    Furthermore, the intermediate transfer belt unit  60  includes an external air supply device  460 . 
         [0082]    The external air supply device  460  is used as a device supplying external air toward the second power supply unit  420  and includes an intake duct  462 , a blast fan  464 , and an exhaust duct  466 . The intake duct  462  and the blast fan  464  are installed to the left side plate  104  and the exhaust duct  466  is installed to the right side plate  102 . In the external air supply device  460 , as the blast fan  464  revolves, external air is brought into the image forming apparatus main body  12  (see  FIG. 1 ) through the intake duct  462  and let out of the image forming apparatus main body  12  through the exhaust duct  466 . 
         [0083]    The second power supply unit  420  is shown in  FIG. 8 . 
         [0084]    The second power supply unit  420  includes the power supply substrate  422 , as already mentioned. The power supply unit  420  also has a bottom plate  424  beneath the power supply substrate  422 , a front plate  426  positioned in the front, and a rear plate  428  in the rear. A space S surrounding the power supply substrate  422  is defined by the bottom plate  424 , the front plate  426 , the rear plate  428 , and the image forming apparatus main body  12 . The thus defined space S surrounding the power supply substrate  422  is intended to keep the user from coming in contact with the power supply substrate  422  and prevent electric shock and a similar accident. 
         [0085]    Air enters the space S through the intake duct  462  (see  FIG. 7 ) and the air inside the space S is let out through the exhaust duct  466  (see  FIG. 7 ). Thus, an air flow takes place inside the space S from the back to the front in  FIG. 8 . In this way, the space S serves as a duct through which air flows. 
         [0086]    The air flow inside the space S cools down the power supply substrate  422  and also cools down the intermediate transfer belt  62  moving beneath the space S. The air flow occurring in the space S impedes heat transfer from one end of the air flow to the other end. Consequently, this impedes the transfer of heat generated from the fixing device  50  (see  FIG. 2 ) located before the second power supply unit  420  to the developer remover  350  located behind the second power supply unit  420 . Accordingly, developer particles received in the developer remover  350  become hard to melt by heat. 
         [0087]      FIG. 9  is a block diagram illustrating power feeding in the image forming apparatus  10 . 
         [0088]    As shown in  FIG. 9 , the image forming apparatus  10  includes a control circuit  600 , and the first power supply unit  410  and the second power supply unit  420  are controlled by the control circuit  600 . 
         [0089]    The first power supply unit  410  supplies a high voltage to the development devices  46 Y,  46 M,  46 C,  46 K, and the second transfer device  84 . In this way, the first power supply unit  410  installed in the image forming apparatus main body  12  feeds power to the development devices  46 Y,  46 M,  46 C,  46 K, and the second transfer device  84  which are also installed in the image forming apparatus main body  12 . 
         [0090]    The second power supply unit  420  supplies a high voltage to the first transfer devices  80 Y,  80 M,  80 C,  80 K. In this way, the second power supply unit  420  installed in the main opening/closing part  26  feeds power to the first transfer devices  80 Y,  80 M,  80 C,  80 K also installed in the main opening/closing part  26 . This power feeding scheme avoids dense wiring for power feeding and shortens the wiring length, as compared with, for example, a case where power is distributed by wiring from the first power supply unit  410  to the first transfer devices  80 Y,  80 M,  80 C,  80 K, the wiring extending from the first power supply unit  410  in a vertical direction inside the image forming apparatus main body  12 . 
         [0091]    Next, an image forming apparatus  10  in accordance with a second exemplary embodiment of the invention is described. In the following description, descriptions of parts that are common to the image forming apparatus  10  in accordance with the above-described first exemplary embodiment are omitted and parts that differ from the above-described first exemplary embodiment are only described. 
         [0092]    The image forming apparatus  10  in accordance with the second exemplary embodiment of the invention is shown in  FIG. 10 . 
         [0093]    As shown in  FIG. 10 , the image forming apparatus  10  in accordance with the second exemplary embodiment includes a protection member  74  serving as a protection part that protects the intermediate transfer belt  62  as a part of the intermediate transfer belt unit  60 , in addition to having all components included in the image forming apparatus  10  in accordance with the above-described first exemplary embodiment. 
         [0094]    The intermediate transfer belt unit  60  integrated in the main opening/closing part  26  of the image forming apparatus  10  in accordance with the second exemplary embodiment of the invention is shown in  FIG. 11 . 
         [0095]    As shown in  FIG. 11 , in addition to having all components included in the image forming apparatus  10  in accordance with the above-described first exemplary embodiment, the image forming apparatus  10  in accordance with the second exemplary embodiment is configured such that a linkage mechanism  406  is connected to, for example, the left side plate  104  of the intermediate transfer belt unit  60 . The above-mentioned protection member  74  (see  FIG. 10 ) is connected to the linkage mechanism  406 . That is, the intermediate transfer belt unit  60  and the protection member  74  are interconnected. The connection to the linkage mechanism  406  may be made via the main opening/closing part  26  united with the intermediate transfer belt unit  60 . 
         [0096]    The second power supply unit  420  included in the image forming apparatus  10  in accordance with the second exemplary embodiment of the invention is shown in  FIG. 12 . 
         [0097]    The second power supply unit  420  has the power supply substrate  422 , as described above. The power supply unit  420  also has the bottom plate  424  beneath the power supply substrate  422 , the front plate  426  positioned in the front, and the rear plate  428  positioned in the rear. A space S 1  surrounding the power supply substrate  422  is defined by the bottom plate  424 , the front plate  426 , the rear plate  428 , and the image forming apparatus main body  12 . The thus defined space S 1  surrounding the power supply substrate  422  is intended to keep the user from coming in contact with the power supply substrate  422  and prevent electric shock and a similar accident. 
         [0098]    Air enters the space S 1  through the intake duct  462  (see  FIG. 7 ) and the air inside the space S 1  is let out through the exhaust duct  466  (see  FIG. 7 ). Thus, an air flow takes place inside the space S 1  from the back to the front in  FIG. 8 . In this way, the space S 1  serves as a duct through which air flows. 
         [0099]    The air flow inside the space S 1  cools down the power supply substrate  422  and also cools down the intermediate transfer belt  62  moving beneath the space S 1 . The air flow occurring in the space S 1  produces a so-called air curtain and impedes heat transfer from one end to the other end with respect to a position where the air flow is formed in a direction intersecting with the air flow direction. Consequently, this impedes the transfer of heat generated from the fixing device  50  (see  FIG. 2 ) located before the second power supply unit  420  to the developer remover  350  located behind the second power supply unit  420 . Accordingly, developer particles received in the developer remover  350  become hard to melt by heat. 
         [0100]    The protection member  74  included in the image forming apparatus  10  in accordance with the second exemplary embodiment of the invention is shown in  FIG. 13  and  FIG. 14 . 
         [0101]    The protection member  74  is hinged to, for example, the right side plate  102  and the left side plate  104  of the intermediate transfer belt unit  60  with hinges  76 , so that it can turn and move between a second position shown in  FIG. 13  and a first position shown in  FIG. 14 . Here, the protection member  74  may be hinged to the main opening/closing part  26  united with the intermediate transfer belt unit  60 . 
         [0102]    One end of the protection member  74  opposite to its end supported by the hinges  76  is fitted with a sealing member  78 . For the sealing member  78 , a material such as, e.g., sponge, which deforms by being pushed externally, is used. 
         [0103]    The protection member  74  is connected to the linkage mechanism  406 . Here, the linkage mechanism  406  is connected to, for example, the left side plate  104  of the intermediate transfer belt unit  60 . Consequently, the protection member  74  moves in conjunction with opening and closing of the part including the intermediate transfer belt  62  with respect to the image forming apparatus main body  12 . More specifically, the protection member  74  moves from the second position to the first position in conjunction with opening of the intermediate transfer belt  62  with respect to the image forming apparatus main body  12 . The protection member  74  moves from the first position to the second position in conjunction with closing of the intermediate transfer belt  62  with respect to the image forming apparatus main body  12 . 
         [0104]    In a state where the protection member  74  is positioned in the first position as shown in  FIG. 14 , the protection member  74  covers a part of the intermediate transfer belt  62  to protect the intermediate transfer belt  62 . In this exemplary embodiment, the protection member  74  covers the belt&#39;s front area that the user is likely to touch during work with hands reaching from the front of the apparatus, when the main opening/closing part  26  is open with respect to the image forming apparatus main body  12  (see  FIG. 3 ). More specifically, the protection member  74  covers and protects the belt area between the support roller  68  and the support roller  70  for the intermediate transfer belt  62 . Thereby, the protection member  74  can prevent an operator from directly touching the intermediate transfer belt  62 , when the intermediate transfer belt unit  60  is open with respect to the image forming apparatus main body  12 . 
         [0105]    In a state where the protection member  74  is positioned in the second position as shown in  FIG. 13 , its end fitted with the sealing member  78  contacts the front plate  426  via the sealing member  78 . As a result of the contact of the protection member  74  with the front plate  426 , a space S 2  is defined, surrounded by the protection member  74 , the front plate  426 , and the bottom plate  424 . 
         [0106]    The space S 2  serves as an air passage. That is, air is supplied by the blast fan  464  (see  FIG. 7 ) from the back in  FIG. 13  and  FIG. 14  and flows out of the front in  FIG. 13  and  FIG. 14 . Instead of supplying air into the space S 2  with the blast fan  464 , for example, a fan other than the blast fan  464  may be used. 
         [0107]    The air flow inside the space S 2  cools down the intermediate transfer belt  62  moving beneath the space S 2 . The air flow occurring in the space S 2  produces a so-called air curtain and impedes heat transfer from one end to the other end with respect to a position where the air flow is formed in a direction intersecting with the air flow direction. Consequently, this impedes the transfer of heat generated from the fixing device  50  (see  FIG. 2 ) located before the space S 2  to the developer remover  350  located behind the space S 2 . Accordingly, developer particles received in the developer remover  350  become hard to melt by heat. 
         [0108]    As explained hereinbefore, the present invention can be applied to image forming apparatus such as, for example, copiers, printers, and facsimile equipment. 
         [0109]    The present invention may be embodied in other specific forms without departing from its spirit or characteristics. The described exemplary embodiments are to be considered in all respects only as illustrated and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.