Abstract:
An image forming apparatus includes an opening; an door; a pressing member movable between a pressing position for fixing the cartridge to an image forming position, and a non-pressing position; an interrelating member for interrelations such that (i) with movement from the close position to the open position, the pressing member moves from the pressing position to the non-pressing position, and the cartridge moves from the image forming position to a retracted position, and (ii) with the inverse movement, the cartridge and the pressing member move inversely; and a limiter movable between a position for preventing the cartridge from moving against the pressing force, and a position for permitting the cartridge to move from the image forming position to the retracted position.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to an image forming apparatus which forms an image on recording medium. 
         [0002]    Here, an image forming apparatus means an apparatus which forms an image on recording medium with the use of one of various known image formation principles/methods such as an electrophotographic process, an electrostatic recording process, a magnetic recording process, etc. For example, it includes a copying machine, a printer (for example, laser printer, LED printer, etc.), a facsimile machine, an image displaying apparatus, etc. Recording medium includes means on which an image is formed by an image forming apparatus. It includes a sheet of paper, an OHT sheet, etc. 
         [0003]    A cartridge means a cartridge in which an image bearing component on which an image is formed, and a part or entirety of an image formation section having image formation process means which acts on the image bearing means, are integrally placed. It contributes to an image formation process for forming an image on recording medium, by being removably installed in the main assembly of an image forming apparatus. Hereafter, an image forming apparatus main assembly (which hereafter may be referred to simply as apparatus main assembly) means an image forming apparatus of the cartridge type, minus the cartridges. 
         [0004]    As an image forming component, a component such as an electrophotographic photosensitive component used in an electrophotographic process, a dielectric component used in an electrostatic recording process, a magnetic component used in a magnetic recording process, and also, various components on which an image can be formed with the use of one of various image formation principles/methods, can be used. An image formation process means includes an image formation process device which forms an image by processing image bearing component. 
         [0005]    Hereinafter, for the sake of convenience, the present invention is described with reference to an electrophotographic image forming apparatus of the cartridge type. As a cartridge, a process cartridge and a development cartridge can be listed, for example. 
         [0006]    A process cartridge means a cartridge in which one or more among charging means, developing means, and cleaning means, which are electrophotographic processing means, and an electrophotographic photosensitive component which is an image bearing component, are integrally disposed, and which is removably installable in the apparatus main assembly. That is, a process cartridge includes a cartridge in which developing means as processing means, and an electrophotographic photosensitive component, are integrally disposed, and which is removably installable in the main assembly of an electrophotographic image forming apparatus. 
         [0007]    Further, a process cartridge includes a cartridge in which charging means, developing means or cleaning means, which are processing means, and an electrophotographic photosensitive component, are integrally disposed, and which can be removably installable in the apparatus main assembly. 
         [0008]    A process cartridge in which an electrophotographic photosensitive component and developing means are integrally held is referred to as a process cartridge of the so-called integration type, whereas a process cartridge in which an electrophotographic photosensitive component, and processing means other than developing means, are integrally disposed, is referred to as a process cartridge of the so-called separation type. That is, a process cartridge which is used in combination with a development unit in which developing means is disposed, for forming an image, is referred to as a process cartridge of the so-called separation type. 
         [0009]    A process cartridge can be installed into, or removed from, the apparatus main assembly, by a user himself or herself. Therefore, a process cartridge makes it easier for a user to maintain the apparatus main assembly. 
         [0010]    A development cartridge means a cartridge which has a development roller, stores powdery developer (toner) used for the development of an electrostatic latent image formed on an electrophotographic photosensitive component with the use of the development roller, and is removably installable in the apparatus main assembly. 
         [0011]    In the case of an electrophotographic image forming apparatus which employs a development cartridge, its electrophotographic photosensitive component is attached to the apparatus main assembly, or a cartridge supporting component, or it is disposed in the above described process cartridge of the so-called separation type (in this case, process cartridge does not have developing means). A development cartridge also can be removably installable in the apparatus main assembly by a user. Therefore, a development cartridge can makes it easier for the user to maintain the apparatus main assembly. 
         [0012]    In other words, a cartridge includes the above described process cartridge of the so-called integration type, and also, the above described process cartridge of the so-called separation type. Further, it includes the development cartridge used in combination with the process cartridge of the so-called separation type, and a development cartridge removably installable in the main assembly of an electrophotographic image forming apparatus, the electrophotographic photosensitive component of which is attached to the apparatus main assembly or cartridge supporting component, in such a manner that it can process the electrophotographic photosensitive component. 
         [0013]    There is disclosed in Japanese Laid-open Patent Application 2007-213018, an image forming apparatus which uses replaceable process cartridges, and is structured so that multiple process cartridges can be installed into, or uninstalled from, the apparatus main assembly, by being mounted in the cartridge moving component of the apparatus. There is also disclosed in the same patent application, a structural arrangement for an image forming apparatus, which keeps a process cartridge properly positioned for image formation, by pressing the cartridge with the use of the resiliency of a spring or the like during an image forming operation, and causes the cartridge to be placed in contact with, or moved away from, the electrophotographic photosensitive component, by the opening or closing of the door (component which can be opened or closed) of the apparatus. 
         [0014]    On the other hand, in order to reduce in size a shipment box for a combination of an image forming apparatus and process cartridges therefor so that it is easier for a user to handle the shipment box, it has been a common practice to install process cartridges in the apparatus main assembly before the combination is placed in the shipment box, and place the apparatus in a shipment box made of corrugated board, styrol foam or the like. 
         [0015]    However, it is difficult to keep the process cartridges in their preset positions in the main assembly of an image forming apparatus, with the use of the above described prior art. That is, the above-described pressing force is insufficient to prevent the cartridges in the main assembly of an image forming apparatus from shifting due to the impacts and/vibrations which occur while the apparatus is transported. The above described cartridge pressing force is sufficient to keep the cartridges in the normal positions (image formation positions) against the force to which the cartridges are subjected by the cartridge driving force, electrical contacts, etc., during an image forming operation. However, the amount of the impact to which the cartridges are subjected during the above described transportation of the image forming apparatus reaches several times  10 G- 100 G. Therefore, it is impossible for the above-described cartridge pressing force to prevent the cartridges positioned in the apparatus main assembly before the image forming apparatus is shipped out in the shipment box, from shifting from their normal positions. 
         [0016]    If the pressing force is increased enough for the cartridges to be properly held, the force necessary to operate a door or the like to install or remove the cartridges increases, which in turn reduces usability. 
         [0017]    As described above, the cartridges placed in the apparatus main assembly of an image forming apparatus are likely to shift due to the impacts and vibrations which occur during the transportation of the apparatus. Therefore, the cartridge is likely to displace from their normal positions and/or become damaged, and/or the cartridge pressing mechanism is likely to be damaged, during the transportation of the apparatus. In the case of the prior art, therefore, the cartridges and/or apparatus main assembly is fitted with packing or the like to prevent the cartridges from shifting. However, the packing or the like has to be removed by a user before the image forming apparatus is used. 
       SUMMARY OF THE INVENTION 
       [0018]    Thus, the primary object of the present invention is to prevent the cartridges in their image formation positions in an image forming apparatus from shifting during the transportation of the image forming apparatus, without reducing usability, in order to protect the cartridges and image forming apparatus during the transportation of the apparatus. 
         [0019]    According to an aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording material, wherein a cartridge is detachably mountable, said image forming apparatus comprising an opening through which said cartridge is passed when said cartridge is mounted to and demounted from a main assembly of said apparatus; an openable member movable between a close position for closing said opening and an open position for opening said opening; a pressing member movable between a pressing position for applying a pressing force to said cartridge to fix said cartridge to an image forming position inside said main assembly, and a non-pressing position in which said cartridge is not pressed by said pressing member; an interrelating member for interrelations such that (i) with the movement of said openable member from the close position to the open position, said pressing member is moved from the pressing position to the non-pressing position, and said cartridge is moved from the image forming position to a retracted position, and (ii) with the movement of said openable member from the open position to the close position, said cartridge is moved from the retracted position to the image forming position, and said pressing member is moved from the non-pressing position to the pressing position; and a limiting member movable between a limiting position for preventing said cartridge positioned in the image forming position from moving against the pressing force of said pressing member, and a non-limiting position for permitting said cartridge to move from the image forming position to the retracted position. 
         [0020]    Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is an external perspective view of the image forming apparatus in the first embodiment of the present invention. 
           [0022]      FIG. 2  is a sectional view of the image forming apparatus at a plane parallel to the front surface of the apparatus, as seen from the front side of the apparatus. 
           [0023]      FIG. 3  is an external perspective view of the image forming apparatus when the door of the apparatus is open. 
           [0024]      FIG. 4  is an external perspective view of the image forming apparatus when the cartridge tray of the apparatus is in its outside position which allows the cartridges P to be mounted into, or removed from, the cartridge tray. 
           [0025]      FIG. 5  is a perspective view of the image forming apparatus shown in  FIG. 1 , minus the external shell of the apparatus, showing the interior of the apparatus. 
           [0026]      FIG. 6  is a sectional view of the apparatus shown in  FIG. 5 , at a plane parallel to the front surface of the apparatus, as seen from the front side. 
           [0027]      FIG. 7  is the same as  FIG. 3 , except that  FIG. 7  does not show the external shell of the apparatus in order to show the interior of the apparatus. 
           [0028]      FIG. 8  is a sectional view of the image forming apparatus when the door is open. It shows the cartridge pressing mechanism. 
           [0029]      FIG. 9  is a sectional view of the image forming apparatus when the door is closed. It shows the cartridge pressing mechanism. 
           [0030]      FIG. 10  is a perspective view of the cartridge pressing mechanism and its adjacencies when the door is open. 
           [0031]      FIG. 11  is a perspective view of the cartridge pressing mechanism and its adjacencies when the door is closed. 
           [0032]      FIG. 12  is a drawing of the cartridge pressing component (cartridge movement regulating component). It shows the shape of the cartridge pressing end portion of the component. 
           [0033]      FIG. 13  is a sectional view of the cartridge pressing mechanism of the image forming apparatus in the second embodiment when the door of the apparatus is open. 
           [0034]      FIG. 14  is a sectional view of the cartridge pressing mechanism of the image forming apparatus in the second embodiment when the door of the apparatus is closed. 
           [0035]      FIG. 15  is a perspective view of the cartridge pressing mechanism and its peripheries when the door is open. 
           [0036]      FIG. 16  is a perspective view of the cartridge pressing mechanism and its peripheries when the door is closed. 
           [0037]      FIG. 17  is a sectional view of the cartridge pressing mechanism and its peripheries in the third embodiment, when the door is closed. 
           [0038]      FIG. 18  is a sectional view of the cartridge pressing mechanism and its peripheries in the third embodiment, when the door is closed. 
           [0039]      FIG. 19  is a sectional view of the cartridge pressing mechanism and its peripheries in the third embodiment, when the door is closed. 
           [0040]      FIG. 20  is a sectional view of the peripheral portions of the cartridge pressing mechanism in the third embodiment, when the door is closed. 
           [0041]      FIG. 21  is a sectional view of the cartridge pressing mechanism and its peripheries in the third embodiment, when the door is closed. 
           [0042]      FIG. 22  is a sectional view of the cartridge pressing mechanism and its peripheries in the fourth embodiment, when the door is closed. 
           [0043]      FIG. 23  is a sectional view of the cartridge pressing mechanism and its peripheries in the fourth embodiment, when the door is closed. 
           [0044]      FIG. 24  is a sectional view of the cartridge pressing mechanism and its peripheries in the fourth embodiment, when the door is closed. 
           [0045]      FIG. 25  is a perspective view of the cartridge pressing mechanism and its peripheries in the fourth embodiment, when the door is closed. 
           [0046]      FIG. 26  is a perspective view of the cartridge pressing mechanism and its peripheries in the fourth embodiment, when the door is closed. 
           [0047]      FIG. 27  is a sectional view of the cartridge pressing mechanism and its peripheries in the fifth embodiment, when the door is closed. 
           [0048]      FIG. 28  is a sectional view of the cartridge pressing mechanism and its peripheries in the fifth embodiment, when the door is closed. 
           [0049]      FIG. 29  is a sectional view of the cartridge pressing mechanism and its peripheries in the fifth embodiment, when the door is closed. 
           [0050]      FIG. 30  is a sectional view of the cartridge pressing mechanism and its peripheries in the fifth embodiment, when the door is closed. 
           [0051]      FIG. 31  is a sectional view of the cartridge pressing mechanism and its peripheries in the fifth embodiment, when the door is closed. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
     General Structure of Example of Image Forming Apparatus 
       [0052]      FIG. 1  is an external perspective view of the image forming apparatus  100  in the first embodiment of the present invention.  FIG. 2  is a sectional view of the apparatus at a plane parallel to the front surface of the apparatus, as seen from the right side of the apparatus. First, referring to  FIGS. 1 and 2 , the general structure of the image forming apparatus  100  in this embodiment is described. The image forming apparatus  100  in this embodiment uses an electrophotographic process. It is a full-color laser printer based on four primary colors. Further, it is of the cartridge type. It forms an image on a sheet S of paper (recording medium), in response to electrical image formation signals inputted into the control section of the apparatus from an external host apparatus (unshown) such as a personal computer, an image reader, a facsimile machine (on transmitting side), etc. 
         [0053]    In the following description of the embodiments of the present invention, regarding the directions of the image forming apparatus  100 , or image forming apparatus main assembly  100  (image forming apparatus minus cartridges, which will be referred to simply as apparatus main assembly), the front side (front surface side) means the side where the door (opening/closing component)  31  is present. The rear side is the opposite side from the front side. The frontward/rearward direction means both the front-to-rear direction and the rear-to-front direction. The left and right means the left and right as seen from the front side. The left/right direction means both the leftward and rightward directions. The upward/downward means the upward/downward in terms of the direction parallel to the gravity direction. 
         [0054]    In the apparatus main assembly  101 , four process cartridges, more specifically, the first to fourth process cartridges (which will be referred to simply as cartridge) P (PY, PM, PC and PK) are roughly horizontally aligned in parallel (inline structure, tandem type) in the rear-to-front direction. 
         [0055]    A cartridge P is a cartridge in which a part or entirety of the image forming section which has an image bearing component, on which an image is formed, and image formation process means which processes the image bearing component, are integrally disposed. It is removably installed in the main assembly of the image forming apparatus to be made to contribute to the image formation process for forming an image on recording medium. 
         [0056]    In this embodiment, each cartridge P is of the integration type. The four cartridges P are different only in the color of the toner (developer) they store in their developing device. In terms of the electrophotographic image process system (image formation section) they have, they are the same. That is, each cartridge P has: an electrophotographic photosensitive drum (which will be referred to simply as drum)  1  as the image bearing component (first image bearing component). It has also a charging device  2  as image formation process means which processes the drum  1 ; a developing device  3 ; and a cleaning device  4 . The abovementioned drum  1 , charging device  2 , and cleaning device  4  are integrally attached to the inward side of the cartridge frame  5 . 
         [0057]    The charging device (charging means)  2  is a charge roller, which contacts the drum  1 . The developing device (developing means)  3  has a development roller  3   a , and stores developer (toner) in its developer container. The cleaning device (cleaning means)  4  is of the blade type; it has a blade which contacts the drum  1 . The lengthwise direction is the direction parallel to the rotational axis of the drum  1 . The portion of the apparatus main assembly  101 , which is for allowing each cartridge P to be installed into, or removed from, the apparatus main assembly  101 , will be described later. 
         [0058]    When each cartridge P is in its preset image formation position (normal position) in the apparatus main assembly  101 , it remains immovably held in the image formation position by a preset cartridge positioning section, which will be described later. Further, the driving force input section (unshown) of each cartridge P is in engagement with the driving force output section of the apparatus main assembly  101 , enabling thereby the driving force to be inputted into each cartridge P from the apparatus main assembly  101 . 
         [0059]    Further, the electrical contacts (unshown) of each cartridge P are in connection to the electrical power supply system (unshown) of the apparatus main assembly  101 , making it possible for bias voltages (charge bias, development bias, etc.,) to be inputted into each cartridge P from the apparatus main assembly  101 . 
         [0060]    The first cartridge PY stores toner of yellow (Y) color, in its developing device  3 . It forms a toner image of yellow (Y) color on the peripheral surface of the drum  1 . The second cartridge PM stores toner of magenta (M) color in its developing device  3 . It forms a toner image of the M color on its drum  1 . The third cartridge PC stores toner of cyan (C) color in its developing device  3 . It forms a toner image of the C color. The fourth cartridge PK stores toner of black (K) color in its developing device  3 . It forms toner image of the K color on the peripheral surface of its drum  1 . 
         [0061]    There is disposed a laser scanner unit  11  as drum exposing means, above the combination of the first to fourth cartridges PY, PM, PC and PK. This scanner unit  11  scans (exposes) the peripheral surface of the drum  1  of each cartridge P, through an exposure window  6  with which the top wall of the cartridge frame  5  is provided, by outputting a beam L of laser light while modulating the beam L according to the information of each of the four monochromatic images, different in color, outputted from the external host (unshown). 
         [0062]    There is disposed an intermediary transfer belt unit  12  below the combination of the first to fourth cartridges PY, PM, PC and PK. This belt unit  12  has: an endless belt  13 , which is a flexible image transferring component made of a dielectric substance; and a combination of a driver roller  14  which circularly moves the endless belt  13 , a tension roller  15 , and an auxiliary roller  14   a , by which the endless belt  13  is suspended and kept tensioned. The driver roller  14  and auxiliary roller  14   a  are disposed in the rear portion of the apparatus main assembly  101  (first cartridge PY side). The tension roller  15  is disposed in the front portion (fourth cartridge PK side) of the apparatus main assembly  101 . 
         [0063]    Each cartridge P is in contact with the top surface of the belt  13 , that is, the outward surface of the top portion of the belt  13 , in terms of the loop which the belt  13  forms. There are disposed four primary transfer rollers  17 , in the inward side of the belt loop, in such a manner that they oppose the drums  1  in the four cartridges P, one for one. The area of contact (nip) between the drum  1  of each cartridge P, and the belt  11 , is the primary transfer station. There are disposed the second transfer roller  22  in such a manner that it is pressed against the driver roller  14  with the presence of the belt  13  between itself and the driver roller  14 . The area of contact (nip) between the secondary transfer roller  22  and belt  13  is the secondary transfer station. 
         [0064]    There is disposed a sheet feeding/conveying unit  18  below the belt unit  12 . This sheet feeding/conveying unit  18  has: a sheet feeder tray  19 , in which multiple sheets S of paper, as recording medium, are stored in layers; a sheet feeder roller  80 ; a sheet conveyance roller  20 ; a separation roller  21 , etc. The sheet feeder tray  19  can be pulled out of, or put back into, the apparatus main assembly  101 , from the front side of the apparatus main assembly  101  (front loading). 
         [0065]    There is disposed in the rear section of the apparatus main assembly  101 , a sheet conveyance upward passage  25 , which extends from the sheet conveying bottom roller  20  to the sheet discharge outlet  26 , which is at the top of the apparatus main assembly  101 . Further, there are disposed a pair of registration rollers (conveyance rollers)  81   a  and  81   b , the secondary transfer roller  22 , a fixing device  23 , and a pair of sheet discharge rollers  24 , along this sheet conveyance passage  25 , listing from the bottom side. A part of the top surface of the apparatus main assembly  101  is used as a delivery tray  27 . The fixing device  23  used in this embodiment has a fixation film assembly  23   a  and a pressure roller  23   b . The pair of discharge rollers  24  are the sheet discharge rollers  24   a  and  24   b.    
       (Image Forming Operation) 
       [0066]    The operation for forming a full-color image is as follows: The drum  1  in each of the first-fourth cartridges PY, PM, PC and PK is rotationally driven in the counterclockwise direction indicated by an arrow mark  2  at a preset control speed. The belt  13  is circularly driven in the clockwise direction indicated by an arrow mark in  FIG. 2 , at a preset speed, which corresponds to the speed of the drum  1 . 
         [0067]    The scanner unit  11  also is driven. In synchronism with this driving of the scanner unit  11 , the charge roller  2  in each cartridge P uniformly charges the peripheral surface of the drum  1  to preset polarity and potential level with a reset control timing. The charge roller  2  is rotated by the rotation of the drum  1 . The scanner unit  11  scans (exposes) the peripheral surface of the drum  1  with the beam L of laser light it outputs while modulating the beam L with the image formation signals which correspond one for one to the monochromatic toner images, different in color, into which the original has been separated. Consequently, an electrostatic latent image, which reflects the image formation signals of the corresponding color is formed on the peripheral surface of the drum  1 . The formed electrostatic latent image is developed as a toner image by the developing device  3 . 
         [0068]    Through the electrophotographic image formation process, a toner image of the Y color, which corresponds to the Y color component of the full-color image is formed on the drum  1  of the first cartridge PY. Then, the toner image is transferred (primary transfer) onto the belt  13 . 
         [0069]    On the peripheral surface of the drum  1  of the second cartridge PM, a toner image of the M color, which corresponds to the M color component of the full-color image is formed. Then, the toner image of the M color is transferred (primary transfer) onto the belt  13  in such a manner that it is laid upon the toner image of the Y color, which has just been transferred (primary transfer) onto the belt  13 . 
         [0070]    On the peripheral surface of the drum  1  of the third cartridge PC, a toner image of the C color, which corresponds to the C color component of the full-color image is formed. Then, the toner image is transferred (primary transfer) onto the belt  13  in such a manner that it is laid upon the combination of the toner image of the Y color, and the toner image of the M color, which have just been transferred (primary transfer) onto the belt  13 . 
         [0071]    On the peripheral surface of the drum  1  of the fourth cartridge PK, a toner image of the K color, which corresponds to the K color component of the full-color image, is formed. The toner image is transferred (primary transfer) onto the belt  13  in such a manner that it is laid upon the combination of the Y, M and C color images, which have just been transferred (primary transfer) onto the belt  13 . 
         [0072]    Consequently, an unfixed full-color image is synthetically effected on the belt  13 , by the toner images of the Y, M, C and K colors, respectively. In each cartridge P, the transfer residual toner, or the toner remaining on the peripheral surface of the drum  1  after the primary transfer of the toner image onto the belt  13 , is removed by the cleaning device  4 . 
         [0073]    Meanwhile, the sheet feeder roller  80  begins to be driven with a preset control timing, whereby the one of the sheets S of paper as the recording medium stored in layers on the sheet feeder tray  19  is separated from the rest on the tray  19  by the separation roller  21 , and is conveyed into the apparatus main assembly  101 . Then, the sheet S is introduced into the nip (secondary transfer station) between the secondary transfer roller  22  and belt  13 , by way of the pair of registration rollers  81   a  and  81   b . Thus, the four toner images, different in color, layered on the belt  13  are transferred together onto the surface of the sheet S while the sheet S is conveyed, remaining pinched between the belt  13  and secondary transfer roller  22 , as if they are peeled away from the belt  13 . 
         [0074]    Then, the sheet S is separated from the surface of the belt  13 , and is introduced into the fixing device  23 , in which it is subjected to heat and pressure in the fixation nip. Consequently, the four toner images, different in color, become fixed to the sheet S while being mixed. Then, the sheet S is moved out of the fixing device  23 , and discharged as a full-color print by the pair of discharge rollers  24  onto the delivery tray  25  through the discharge opening  25 . 
         [0075]    In this embodiment, the secondary transfer residual toner, which is the toner remaining on the surface of the belt  13  after the separation of the sheet S, is electrostatically adhered to the peripheral surface of the drum  1  in the primary transfer station of the first cartridge PY, for example, and then, is removed by the cleaning device  4 . 
       (Method for Replacing Cartridge) 
       [0076]    The image forming apparatus  100  in this embodiment is of the so-called front access type. That is, the cartridges P are placed on the tray  35  which can be pulled out of the apparatus main assembly  101 . Thus, when it is necessary to replace one or more of the cartridges P in the apparatus main assembly  101 , the tray  35  can be pulled out of the apparatus main assembly  101  so that any or all of the cartridges P can be replaced.  FIG. 4  shows the state of the image forming apparatus  100 , in which the tray  35  has been pulled out of the apparatus main assembly  101 , into the position in which the cartridges P can be placed in, or moved out of, the tray  35 . 
         [0077]    The front wall of the apparatus main assembly  101  is provided with an opening  30  through which the tray  35  can be moved in order to install the cartridges P into, or remove the cartridges P from, the apparatus main assembly  101 . Further, the apparatus main assembly  101  is provided with a door (opening/closing component)  31 , which can be pivotally moved between an open position A in which it keeps the opening  30  closed, and a closed position B in which it keeps the opening  30  exposed. 
         [0078]    In this embodiment, the door  31  is pivotally movable relative to the apparatus main assembly  101 , about the horizontal shaft (hinge shaft)  32 , which is at the bottom edge of the door  31 . That is, referring to  FIGS. 1 and 2 , the door  31  can be pivotally moved about the shaft  32  so that it will be in the position A, in which the door remains upright, keeping thereby the opening  30  closed. Next, referring to  FIG. 3 , the door  31  can also be pivotally moved frontward about the shaft  32  into the position B, in which the door  31  remains horizontal, leaving thereby the opening  30  fully exposed. A referential code  31   a  stands for a handhold with which the door  31  is provided. 
         [0079]      FIG. 5  is a perspective view of the image forming apparatus  100 , minus the external shell, and shows the interior of the apparatus  100 .  FIG. 6  is a sectional view of the image forming apparatus  100  which is in the state shown in  FIG. 5 , as seen from the front side of the apparatus  100 .  FIG. 7  is a perspective view of the image forming apparatus  100 , minus its external shell, which is in the state shown in  FIG. 3 . It also shows the interior of the image forming apparatus  100 . 
         [0080]    Referring to  FIGS. 5-7 , referential codes  101   a  and  101   b  stand for the left and right plates of the main frame of the apparatus main assembly  101 . Referring to  FIG. 6 , there are disposed a pair of tray rails  36   a  and  36   b  (left and right rails), on the inward surfaces of the left and right frame plates  101   a  and  101   b , respectively, in such a manner that they extend in the frontward/rearward direction and oppose each other. The tray  35  is held by these left and right tray rails  36   a  and  36   b  in such a manner that the tray  35  can be horizontally slid in the frontward/rearward direction. The cartridges P are supported by the tray  35 , being aligned in parallel in the frontward/rearward direction. 
         [0081]    The left and right trail rails  36   a  and  36   b  are moved by the opening and closing movement of the door  31 , in the manner which will be described next. 
         [0000]    1) When Door  31  is Moved from Open Position B to Closed Position A 
         [0082]    As the door  31  is moved from the open position B to the closed position A, a lever  37  linked to the door  31  is moved from the front side to the rear side (FIG.  7 → FIG. 5 ). The apparatus main assembly  101  is provided with two levers  37 , which are attached to the left and right frame plates  101   a  and  101   b , one for one, being thereby symmetrically positioned in terms of the left/right direction. Thus, the left and right levers  37  are moved rearward from the front side, along the left and right tray rails  36   a  and  36   b , by the bosses  38  which are integral parts of the left and right trail rails  36   a  and  36   b , one for one. The bosses  38  of the left and right tray rails  36   a  and  36   b  are fitted in the guide grooves  44 , with which left and right stationary components (right one is not shown) of the apparatus main assembly  101 . 
         [0083]    As the bosses  38  are moved rearward along the guide grooves  44  which correspond one for one to the bosses  38 , the left and right tray rails  36   a  and  36   b  are diagonally moved by a preset amount. That is, they are moved rearward by the preset amount while being moved downward. With the left and right tray rails  36   a  and  36   b  moved as described above, the tray  35  also is moved downward by a preset amount in the apparatus main assembly  101  while remaining parallel to the left and right tray rails  36   a  and  36   b . As the tray  35  is downwardly moved by the preset amount, it is stopped by the action of the stopper (unshown), being thereby fixed in position relative to the apparatus main assembly  101 . 
         [0084]    Each cartridge P is provided with cartridge positioning portions  47  ( 47 Y,  47 M,  47 C and  47 K, by which cartridge P is held properly positioned), which are specifically shaped for cartridge positioning. One of them is located at the intersection of the lengthwise bottom left edge and one of the widthwise bottom edges, whereas the other is located at the intersection of the lengthwise bottom right edge and the same widthwise bottom edge. Further, the cartridge positioning left and right plates  45  of the apparatus main assembly  101  are provided with cartridge positioning portions  46  ( 46 Y,  46 M,  46 C and  46 K), which correspond in position to the cartridge positioning portions (specifically shaped portions)  47  of the cartridge P. 
         [0085]    As the tray  35  moves downward, the cartridges P supported by the tray  35  also move downward. Consequently, the cartridge positioning portions  47  of each cartridge P engage with the cartridge positioning portions  46  of the apparatus main assembly  101  (FIG.  8 → FIG. 9 ). That is, as the door  31  is moved from the open position B to the closed position A while the cartridges P are in the apparatus main assembly  101 , the cartridges P are moved from their installation/removal positions ( FIG. 8 ) in which they can be placed in, or removed from, the tray  35 , to their image formation positions ( FIG. 9 ). 
         [0086]    As the cartridges P are moved into their image formation positions, spring cartridge holders  42  ( 42 Y,  42 M,  42 C and  42 K), as a cartridge pressing elastic components, with which the apparatus main assembly  101  is provided, and which correspond in position to the cartridges P one for one, are made to move. That is, each spring cartridge holder  42  is made to move from a no pressure position D ( FIGS. 8 and 10 ) in which it does not apply pressure to the cartridge P, to a pressure application position C ( FIGS. 9 and 11 ) in which it contacts the top surface of the cartridge P. As each spring cartridge holder  42  is moved to the pressure application position C, it applies a preset amount of pressure to the top surface of the corresponding cartridge P. Consequently, the cartridge positioning portion of each cartridge P is pressed upon the cartridge positioning portion  46  of the apparatus main assembly  101 , causing thereby the cartridge P to be fixed in position relative to the apparatus main assembly  101 . 
         [0087]    That is, each cartridge P is moved into its image formation position in the apparatus main assembly  101 , and is reliably kept in the image formation position. When the cartridges P are in their image formation positions, the downwardly facing portion of the peripheral surface of the drum  1  is in contact with the surface of the belt  13  in a preset manner. Further, the driving force outputting section (unshown) of the apparatus main assembly  101  is connected to the driving force input section (unshown) of each cartridge P disposed in its image formation position. Further, the power supply system (unshown) of the apparatus main assembly  101  is connected to the electric power input section of the cartridge P. It is when the image forming apparatus  100  is in the above-described state that the image forming apparatus  100  is capable of forming images. 
         [0000]    2) When Door  31  is Moved from Closed Position A to Open Position B 
         [0088]    As the door  31  is opened, the image forming apparatus  100  is made to follow in reverse the above-described steps, which occur as the door  31  is closed. 
         [0089]    That is, during the initial stage of the opening of the door  31 , the operation for disengaging the driving force output section of the apparatus main assembly  101  from the driving force input section of each cartridge P is carried out. Further, each spring cartridge holder  42  is moved from the positions C in which it applies pressure to the cartridge P, to the position D in which it does not apply pressure to the cartridge P; the operation for freeing the cartridge P from the pressure applied to thereto by the spring cartridge holder  42  is carried out. Moreover, the tray  31  is unlocked from the apparatus main assembly  101 . 
         [0090]    Then, as the door  31  is opened further, the bosses  38  of the left and right tray rails  36   a  and  36   b  are diagonally moved frontward by the preset amount by the pivotal movement of the door  31  in the opening direction. That is, the tray is moved frontward while being vertically moved upward. With the above described movement of the left and right tray rails  36   a  and  36   b , the tray  35  also moves upward by a preset amount in parallel to the tray rails  36   a  and  36   b . Therefore, each of the cartridges P held by the tray  35  is also moved upward. 
         [0091]    Consequently, the cartridge positioning portions  47  of each cartridge P move upward away from the cartridge positioning portions  46  of the apparatus main assembly  101  (FIG.  9 → FIG. 8 ). That is, each cartridge P is moved from its image formation position ( FIG. 9 ) to the no-image-formation position ( FIG. 8 ). Further, the downwardly facing portion of the peripheral surface of the drum  1  in each cartridge P separates from the belt  13 . Further, as the door  31  is fully opened to be placed into the open position B as shown in  FIG. 3 , the opening  30  is fully exposed, allowing thereby the tray  35  to be pulled out of the apparatus main assembly  101 . 
         [0092]    That is, as the door  31  is pivotally moved from the closed position A to the open position B when each cartridge P is in the apparatus main assembly  101 , each cartridge P is moved from its image formation position to its no-image-formation position. Then, a user is to grasp the handhold  31   a  exposed through the opening  30  as shown in  FIG. 3 , and to horizontally slide the tray  31  frontward relative to the tray rails  36   a  and  36   b.    
         [0093]    The user is to pull out the tray  35  from the apparatus main assembly  101  through the opening  30 , until it is moved into the preset cartridge installation/removal position (outermost tray position), as shown in  FIG. 4 . Consequently, the entire cartridges P held by the tray  35  are moved out of the apparatus main assembly  101  through the opening  30 , being thereby fully exposed upward from the apparatus main assembly  101 . 
         [0094]    As the tray  35  is pulled out by a preset distance, that is, such a distance that is enough to expose the entire process cartridges P, it is stopped by the stopper (unshown), being thereby prevented from sliding out of the apparatus main assembly  101  by an unnecessary distance. Further, once the tray  35  is pulled out of the apparatus main assembly  101  and placed in the cartridge installation/removal position, it is horizontally and securely held in the position by the tray rails  36   a  and  36   b . With the employment of this structural arrangement, the cartridges P can be replaced from the front side of the apparatus main assembly  101 , without changing the belt  31  in position. 
         [0095]    The tray  35  loosely supports each cartridge P so that the cartridge P can be easily removed upward from the tray  35 , and also, so that the cartridge P can be supported by the tray  35  by being positioned above the tray  35 , and then, moved straight downward. Thus, when it is necessary to replace a cartridge P (toner-depleted cartridge or the like) in the tray  35 , the cartridge is to be extracted upward from the tray  35 , and then, a new cartridge P (replacement cartridge) is to be fitted straight downward into the vacated cartridge space in the tray  35 . 
         [0096]    After the replacement of the old (depleted) cartridge with a fresh one, the tray  35 , which is outside the apparatus main assembly  101 , is to be horizontally slid rearward into the apparatus main assembly  101  along the tray rails  36   a  and  63   b , through the opening  30 , following in reverse the above described steps followed to pull the tray  35  out of the apparatus main assembly  101 , until the tray  35  is stopped by the stopper (unshown) for preventing the tray  35  from being pushed farther into the apparatus main assembly  101 . 
         [0097]    Then, the door  31  is to be pivotally moved in the closing direction. As the door  31  is pivotally moved, the operation described in Section 1) is carried out, whereby each cartridge P is positioned in its image formation position in the apparatus main assembly  101 . That is, the image forming apparatus  100  becomes ready for an image forming operation. 
         [0098]    The tray  35  is a drawer which supports multiple (four in this embodiment) cartridges P. It is movable in the direction perpendicular to the lengthwise direction of the cartridge P, and is enabled to take the inward position in which it is within the apparatus main assembly  101 , and the outward position into which it is put as it is pulled out of the apparatus main assembly  101  through the opening  30 , and in which it allows the cartridges P to be installed into, or removed from, the tray  35 . 
         [0099]    Further, the linkage  37 , bosses  38 , tray rails  36   a  an  36   b , stationary components  102  having the guide grooves  44 , and tray  35  are the components which are moved by the opening or closing of the door  31  to move the cartridges P between their image formation positions and no-image-formation position, in the apparatus main assembly  101 . 
       (Structure of Cartridge Pressing Means) 
       [0100]    As described above, when the cartridges P are in the apparatus main assembly  101  while the door  31  is remaining closed, they remain under a preset amount of pressure generated by the spring cartridge holders ( 42 Y,  42 M,  42 C and  42 K) as cartridge pressing elastic components, remaining thereby fixed in their image formation positions. 
         [0101]    Referring to  FIGS. 5 and 7 , the spring cartridge holders  42  which correspond one for one to the cartridges P are rotatably supported, with the presence of preset intervals, by a long guiding component  70 , which is solidly attached to the left frame plate  101   b  in such an attitude that its lengthwise direction is parallel to the frontward/rearward direction. Each spring cartridge holder  42  is provided with an internal spring  43  ( 43 Y,  43 M,  43 C and  43 K) ( FIGS. 10 and 11 ). 
         [0102]    Next, referring to  FIGS. 5 and 7 , the cartridge pressing means is provided with a long rod  40 , which is attached to the underside of the left frame plate  101   b , in such a manner that its lengthwise direction is parallel to the frontward/rearward direction, and also, that it is slid in the frontward/rearward direction. The rod  40  is in indirect connection to the door  31 , with the presence of a linkage (lever)  39  between itself and the door  31 . With the presence of this linkage, as the door  31  is moved from its open position B to its closed position A, the rod  40  is moved rearward from its frontmost position E ( FIGS. 5 and 11 ) to its rearmost position F ( FIGS. 5 and 11 ) by the movement of the door  31 . 
         [0103]    There are disposed cam grooves  41  ( 41 Y,  41 M,  41 C and  41 K), which correspond one for one to the spring cartridge holders  42 , in such a manner that their lengthwise directions are parallel to the lengthwise direction of the rod  40 , and also, that roller (cam follower)  42   b , with which the arm  42   a  of each spring cartridge holder  42  is provided, fits in the corresponding cam groove  41 . 
         [0104]    With the employment of the above described structural arrangement, the spring cartridge holder  42  is moved into the pressure application position C ( FIGS. 9 and 11 ) where it applies pressure to the cartridge P, by the closing movement of the door  31 , or its inaction position D where it does not apply pressure to the cartridge P, by the opening movement of the door  31 . That is, as the door  31  is moved from its closed position A to its open position B, the spring cartridge holder  42  is moved from its pressure application position C to its no-pressure position D, by the movement of the door  31 . Further, as the door  31  is moved from its open position B to its closed position A, the spring cartridge holder  42  is moved from its no-pressure position D to its pressure application position C, by the movement of the door  31 . 
         [0105]    As the door  31  is closed, the rod  40  is moved in the frontward direction E by the linkage  39 . Thus, each spring cartridge holder  42  is pivotally driven by the combination of the cam groove  41  and roller  42   b , in the direction to move from the no pressure application position D to the pressure application position C, coming into contact with the top surface of the cartridge P and applying therefore the preset amount of pressure to the cartridge P. Thus, the cartridge P is pressed upon the cartridge positioning plate  45 , being thereby properly positioned relative to the tray  35  (apparatus main assembly  101 ) ( FIGS. 9 and 11 ). 
         [0106]    On the other hand, as the door  31  is opened, the rod  40  is moved in the rearward direction F by the linkage  39  which is between the door  31  and rod  40 . Thus, the each spring cartridge holder  42  is pivotally driven by the combination of the cam groove  41  and roller  42   b , in the direction to move from the pressure application position C to the no pressure application position D, moving away (separating) from the top surface of the cartridge P ( FIGS. 8 and 10 ), allowing thereby the tray  31  and cartridges P therein to move upward ( FIG. 8 ). Thereafter, the tray  35  can be pulled out of the apparatus main assembly  101  to replace the cartridges P, as described above. 
         [0107]    In the description of the structure of the cartridge pressing means given above, the linkage  39 , rod  40 , cam groove  41 , and roller  42   b , make up the component which causes the spring cartridge holder  42  to be moved into its pressure application position C or its no pressure application position D, by the closing or opening of the door  31 . 
       (Cartridge Movement Regulating Component) 
       [0108]    Referring to  FIGS. 10 and 11 , there are disposed cartridge pressing components  50  ( 50 Y,  50 M,  50 C and  50 K) as cartridge movement regulating components, in the adjacencies of the cartridge pressing mechanism made up of the spring cartridge holder  42  and its internal spring  43 . Each cartridge pressing component  50  is disposed in the adjacencies of the corresponding spring cartridge holder  42 , being supported by the guiding component  70  so that it can be pivotally moved relative to the guiding component  70 . 
         [0109]    Each pressing component  50  is in engagement with the corresponding spring cartridge holder  43  and gears  42   c  and  52 . The gear  42   c  is an integral part of the spring cartridge holder  42 , and is concentric with the spring cartridge holder  42 . The gear  52  is an integral part of the pressing component  50 , and is concentric with the pressing component  50 . 
         [0110]    With the employment of the above-described structural arrangement, as the door  31  is opened or closed, the spring cartridge holder  42  is pivotally moved by the movement of the door  31 , and therefore, each pressing component  50  is rotated by the pivotal movement of the corresponding spring cartridge holder  42 . Therefore, the cartridge pressing portion  51 , which is an integral part of the pressing component  50  as the cartridge regulating component, is pivotally moved about the axial line of the pressing component  50 . That is, as the door  31  is opened, this cartridge pressing portion  51  is moved into its non-regulation position ( FIGS. 8 and 10 ) in which it is away from the top surface of the cartridge P, whereas as the door  31  is closed, the cartridge pressing portion  51  is moved into its regulating position ( FIGS. 9 ,  11  and  12 ) in which it presses on the top surface of the cartridge P; the cartridge pressing portion  51  is moved between the no-regulation position and regulating position. 
         [0111]    That is, as the door  31  is moved from its open position B to its closed position A, the pressing component  50  regulates the cartridge P in movement, by being moved by the movement of the door  31  into the proximity position G in which it is near the cartridge P which is in its image formation position. When the regulating portion  51  is opposing the cartridge P with the presence of a gap between the regulating portion  51  and cartridge P, the distance between the regulating portion  51  and cartridge P is desired to be large enough to prevent the regulating portion  51  from interfering with the cartridge P, but to be no more than 1 mm. 
         [0112]    Further, as the door  31  is moved from its closed position A to its open position B, the pressing component  50  is moved by the movement of the door  31  into the separation position H in which it remains separated from the cartridge P, allowing thereby the cartridge P to be moved from the image formation position to the non-contact position. Further, the pressing component  50  retracts from the passage through which the cartridges P are moved into, or out of, the apparatus main assembly  101  through the opening  30 . 
         [0113]    In this embodiment, the pressing component  50  moves from its proximity position G to its separation position H by being rotationally moved by the movement of the door  31  from the closed position A to the open position B. Further, it moves from its separation position H to its proximity position G by being rotationally moved by the movement of the door  31  from the open position B to the closed position A. The pressing component  50  is moved by the movement of the door  31  from the closed position A to the opening position B, and the movement of the door  31  from the open position B to the closed position B, with the presence of the spring cartridge holder  42  between the pressing component  50  and door  31 . 
         [0114]    By the way, as described in the section related to “Problems to Be Solved by Present Invention”, the spring  43  prevents the cartridge P from separating from the cartridge positioning plate  45 , by the reaction force and the like generated therein by the driving of the drum  1  during an image forming operation. Therefore, the spring  43  is structured so that it is provided with resiliency necessary to keep the cartridge P in the normal position. 
         [0115]    However, the spring  43  is not to be allowed to be given resiliency strong enough to prevent the cartridge P from being shifted by the vibrations which occur as the image forming apparatus  100  in which the cartridges P are present is transported, and/or impacts which occur as the apparatus is accidentally dropped during the transportation of the apparatus. 
         [0116]    If the pressing component  50  is given resiliency strong enough to prevent the above described problem, the amount of force necessary to open or close the door  31  will be very large, which in turn requires a user to exert a large amount of force to open or close the door  31 , and/or the lever  37 , rod  40 , linkage  39 , etc., may be damaged. 
         [0117]    That is, it is rather difficult to prevent the cartridges P in the image forming apparatus  100  from shifting during the transportation of the apparatus  100 , with the use of only the resiliency of the spring  43 . Therefore, it is possible that during the transportation of the image forming apparatus  100 , the cartridges P in the apparatus main assembly  101  will dislodge from their normal positions; the springs  43  will be deformed by the excessive amount of load to which they are subjected; and/or the spring cartridge holder  42 , rod  40 , etc., will be damaged. 
         [0118]    An example of the conventional art for solving the above described problems was to place spacers or the like dedicated to the transportation of an image forming apparatus, in the adjacencies of the cartridges P, in order to prevent the cartridges P from shifting, by minimizing the gaps which are present between the cartridges P and the adjacent components. However, these spacers or the like have to be removed by a user before the image forming apparatus  100  is put to use for the first time, reducing thereby the image forming apparatus  100  in usability. 
         [0119]    Providing the image forming apparatus with the pressing components  50  as in this embodiment makes it possible to reduce to a very small amount, the distance by which the cartridges P in the image formation positions of the image forming apparatus  100  are made to shift by the impacts which occur during the transportation of the image forming apparatus  100 . Therefore, it can regulate the movement of the cartridges P in the image forming apparatus  100 , without relying on the resiliency of the springs  43 . 
         [0120]    Further, when the pressing components  50  are rotationally moved by the opening and closing movement of the door  31 , the pressing components  50  do not come into contact with the cartridges P, etc. Thus, the pressing components  50  are not subjected to the reaction force generated in the springs, etc. Therefore, the effect of the pressing components  50  upon the amount of the force necessary to open or close the door  31  is negligible. 
         [0121]    Further, as the door  31  is opened, the pressing components  50  are made to separate from the cartridges P. Therefore, they do not interfere with the operation for installing or removing the cartridges P. In other words, they have no effect upon the usability. 
         [0122]    Further, referring to  FIG. 12 , in terms of the cross sectional view perpendicular to the rotational axis of the pressing portion  51 , the pressing portion  51  is arced in such a manner that its curvature is concentric with the rotational axis of the rotational movement of the pressing component  50 . Therefore, even if the cartridges P come into contact with the pressing components  50 , such force that works in the direction to rotate the pressing component  50  is not generated. Therefore, there is virtually no possibility that the pressing components  50  are robbed of their function of preventing the cartridges P from shifting, by being rotated by their contact with the process cartridges P. Therefore, the image forming apparatus  100  is reliable in terms of the prevention of the shifting of the process cartridges P in the apparatus main assembly  101  during the transportation of the image forming apparatus  100 . Here, regarding the material for the pressing components  50 , in order to ensure that the pressing components  50  prevent the shifting of the cartridges P, the pressing components  50  are formed of a resinous substance, such as ABS, the elastic modulus of which is greater than the elastic modulus of the springs  43 . 
         [0123]    As described above, with the employment of the pressing components  50  structured as described above, it is possible to provide an image forming apparatus which can prevent the cartridges in the image forming apparatus, and/or main assembly of the image forming apparatus, from being damaged during the transportation the image forming apparatus, and which is no less in usability than any image forming apparatus in accordance with the prior art. 
       Embodiment 2 
       [0124]    One of the characteristic features of the image forming apparatus in the second embodiment of the present invention is that the cartridge movement regulating component is an integral part of the elastic pressing component. The general structure of the image forming apparatus  100  in the second embodiment is the same as that of the image forming apparatus  100  in the first embodiment. Further, the structural arrangement, in this embodiment, for pressing the cartridges P is roughly the same as that in the first embodiment, as shown in  FIGS. 13 and 14  (sectional views of image forming apparatus when door  31  is open and closed, respective), and  FIGS. 15 and 16  (sectional views of pressing component and its adjacencies when the door  31  is open and closed, respectively). 
         [0125]    The spring cartridge holder  62  in this embodiment corresponds to the spring cartridge holder  42  in the first embodiment. The cartridge pressing portion  64 , with which the spring cartridge holder  62  is provided, is an integral part of the spring cartridge holder  62 , and is shaped so that its cartridge contacting surface is arced so that the center of its curvature coincides with the rotational axis of the spring cartridge holder  62 . The image forming apparatus  100  is structured so that the cartridge pressing portion  64  is in the adjacencies of the corresponding cartridge P. 
         [0126]    With the image forming apparatus  100  being structured as described above, it is possible to enable the spring cartridge holder  62  to have the above described function of the pressing component  50 , making it possible to eliminate the pressing component  50 , which in turn makes it possible to reduce an image forming apparatus in component count and cost. Further, like in the first embodiment, the pivotal axis of the cartridge pressing portion  64  of the spring cartridge holder  62  coincides with the pivotal axis of the spring cartridge holder  64 . Therefore, even if the cartridge P comes into contact with the cartridge pressing portion  64 , the contact does not generate rotational force. Therefore, it is unlikely for the spring cartridge holder  62  to lose its function of regulating the movement of the cartridge P. Therefore, the image forming apparatus in this embodiment is higher in reliability than the one in the first embodiment. 
         [0127]    As described above, by employing the structural arrangement in this embodiment, it is possible to prevent the problem that when an image forming apparatus in which cartridges are positioned in the image formation positions is transported, the cartridges in the image forming apparatus and/or the apparatus main assembly  101  is damaged, without reducing the image forming apparatus in usability, as in the case of the first embodiment. Therefore, it becomes possible to provide an image forming apparatus which is low in cost. 
         [0128]    In the first embodiment, however, the pressing component  50  is made to be greater in resiliency, by the setting of the gear ratio between the gears  42   c  and  52 , which connect between the door  31  and pressing component  50 , than the spring cartridge holder  42 , in the angle by which they are rotated by the opening and closing movement of the door  31 . This structural arrangement sets the distance by which the cartridge pressing portion  51  of the pressing component  50  is separated from the cartridge P. In comparison, in the second embodiment, the distance by which the cartridge pressing portion  64  is separated from the cartridge P has to be set by increasing the angle by which the spring cartridge holder  62  itself is pivotally moved. 
         [0129]    Therefore, the groove  61  with which the rod  60  is provided has to be increased in depth as shown in  FIGS. 15 and 16  (when door  31  is opened and closed, respectively), or the like measure has to be taken, in order to increase the angle (amount) by which the spring cartridge holder  62  (and spring  63 ) is rotated. The amount of force necessary to open or close the door  31  is greater than in the first embodiment, and also, the space necessary, in this embodiment, for the spring cartridge holder  62  itself, and the space for the movement of the spring cartridge holder  63 , is greater than those in the first embodiment. Therefore, in some cases, it is difficult to secure the necessary space, in the apparatus main assembly  101 . 
         [0130]    For the reason given above, the second embodiment is not intended to replace the structural arrangement in the first embodiment, which employs the pressing component  50 . The structural arrangement in the second embodiment should be employed in consideration of the size of an image forming apparatus. 
       Embodiment 3 
       [0131]    Next, referring to  FIGS. 17-21 , the structure of the cartridge pressing means in the third embodiment of the present invention is described. Incidentally, the third to fourth embodiments of the present invention will be described with regard to the structure of the portions of the image forming apparatuses, which are different from the counterparts in the first embodiment. 
         [0132]      FIG. 17  is a schematic sectional view of the combination of the cartridge pressing mechanism  79 , which includes a cartridge pressing component  70 , and the cartridge P, at a vertical plane parallel to the moving direction of the tray  35  ( FIGS. 3 and 4 ).  FIG. 18  is a schematic sectional view of the combination of the cartridge P and cartridge pressing component  70  when the door  31  is closed. It shows the relationship between the pressing component  70  and cartridge P, when the door  31  is closed.  FIG. 19  is a schematic sectional view of the combination of the pressing component  70  and cartridge P after the cartridge P has just been shifted by the impacts and/or the like which occurred during the transportation of the image forming apparatus. It shows the relationship between the pressing component  70  and cartridge P, as seen from the direction parallel to the moving direction of the tray  35 . 
         [0133]    Also in this embodiment, the pressing component  70  is rotationally moved by the rotational movement of the corresponding spring cartridge holder  72 , which is caused by the opening or closing of the door  31 , as in the first embodiment. Thus, the cartridge pressing portion  71  (opposing portion) which is an integral part of the pressing component  70  which is a regulating component is rotationally moved. Consequently, as the door  31  is opened, the pressing portion  71  is moved into the no-regulation position (unshown) in which it remains separated from the top surface of the cartridge P, whereas as the door  31  is closed, the pressing portion  71  is moved into the regulation position ( FIG. 18 ) in which it presses on the top surface of the cartridge P, as shown in  FIGS. 17 and 18 . Further, referring to  FIG. 18 , the pressing component  70  is rotatably supported by the supporting portion  77 , with which the lateral plate  79  of the apparatus main assembly  101  is provided. The pressing portion  71  of the pressing component  70  is tilted relative to the lengthwise direction of the cartridge P. Further, referring to  FIG. 19 , as the cartridge P shifts due to the impacts and the like during the transportation of the image forming apparatus, the positioning portion of the cartridge P comes into contact with the pressing portion  71 , whereby the pressing portion  71  is subjected to a reaction force F1, indicated by an arrow mark, which is made up of a component F2 which acts upward, and a component F3 which acts in the direction parallel to the lengthwise direction of the cartridge P. That is, the component F3 is generated in the direction to prevent the pressing component  70  from disengaging from the supporting portion  77 . Therefore, the pressing component  70  is enabled to regulate the movement of the cartridge P without disengaging from the supporting portion  77 . 
         [0134]    In the third embodiment, the regulating surface of the regulating portion  71  is tilted as shown in  FIG. 18 . However, such a structural arrangement may be made that the regulating surface of the regulating portion  71  is tilted in the opposite direction from the direction in which it is tilted in  FIG. 18 , and the portion  176  of contact of the cartridge P is recessed, as shown in  FIGS. 20 and 21 . The effects of such an arrangement are the same as the effects of the third embodiment. Also in the case of this arrangement, the resultant force F3 from forces F1 and F2 prevents the pressing component  170  from disengaging from the supporting portion  77 . Therefore, it is ensured that the cartridge P is prevented from shifting. 
       Embodiment 4 
       [0135]    Next, referring to  FIGS. 22-24 , the structure of the cartridge pressing mechanism in the fourth embodiment is described. 
         [0136]      FIG. 22  is a schematic sectional view of the cartridge pressing mechanism  89  which includes a pressing component  80 , and the cartridge P, at a plane parallel to the moving direction of the tray  35  ( FIGS. 3 and 4 ). It shows the relationship between the mechanism  89  and cartridge P.  FIG. 23  is the same as  FIG. 22 , except that  FIG. 23  does not show the spring cartridge holder  83  and spring  80  as a pressing component, for convenience.  FIG. 24  is the same as  FIG. 23 , except that  FIG. 24  shows the relationship between the pressing component  80  and cartridge P after the cartridge P was moved by the impact and/or the like which occurred while the image forming apparatus  100  was transported with its door  31  closed. 
         [0137]    Referring to  FIG. 24 , in the case of the cartridge pressing mechanism in this embodiment, even if the portion  86  of contact of the cartridge P is made to contact the cartridge pressing portion  81  of the cartridge pressing component  80 , by the above described impact and/or the like, and therefore, the pressing portion  81  is subjected to rotational force which acts on the pressing portion  81  in the direction indicated by a two-headed arrow mark, the portion  86  of contact of the cartridge P, which is in the form of a recess, can prevent the pressing portion  80  from rotationally moving. Thus, it is ensured that the pressing portion  81  perfectly engages with the portion  86  of contact of the cartridge P. Therefore, it is possible to prevent the cartridge P from being shifted by the impacts and/or the like. 
         [0138]    In the fourth embodiment, the pressing portion  81  is in the form of a protrusion, whereas the portion  86  of contact of the cartridge P is in the form of a recess. However, the relationship in terms of shape between the pressing portion  81  and portion  86  of contact of the cartridge P may be opposite from the one in this embodiment. That is, the pressing portion  81  may be in the form of a recess, whereas the portion  86  of contact of the cartridge P is in the form of a protrusion. In other words, all that is necessary is that one of the pressing portion  81  and the portion  86  of contact of the cartridge P is in the form of a protrusion, and the other is in the form of a recess. The effects of such a structural arrangement are the same of those in this embodiment. 
         [0139]    Further, in the fourth embodiment, the portion  86  of contact of the cartridge P was used to prevent the pressing portion  81  from being rotationally moved by the aforementioned impacts and/or the like. Instead, however, in order to prevent a cartridge pressing component  80  having a cartridge pressing portion  81  which is arced in cross section, from being rotationally moved in the direction indicated by an arrow mark, a supporting portion  87  may be provided with a stopper  85 , as shown in  FIGS. 25 and 26 . With the provision of the stopper  85 , it is ensured that the arc-shaped pressing portion  81  comes into contact with the portion  86  of contact of the cartridge P. It is assumed here that the phase of the stopper  85  is such that the pressing portion  81  comes into contact with the portion  86  of contact of the cartridge P, in spite of the effect of the overall error in dimension of the components of the cartridge pressing mechanism and process cartridge P. Therefore, it is ensured that the pressing portion  81  engages with the portion  86  of contact of the process cartridge P. Therefore, it is possible to regulate the movement of the cartridge P attributable to the impacts and/or the like. 
       Embodiment 5 
       [0140]    Next, referring to  FIGS. 27-31 , the structure of the cartridge pressing mechanism in the fifth embodiment of the present invention is described. 
         [0141]      FIG. 27  is a schematic sectional view of the cartridge pressing mechanism  99  which includes a cartridge pressing component  90 , at a plane parallel to the moving direction of the tray ( FIGS. 3 and 4 ) after the closing of the door (unshown). It shows the relationship between the cartridge pressing mechanism  99  and cartridge P after the closing of the door.  FIG. 28  is the same as  FIG. 27 , except that  FIG. 28  does not show the spring cartridge holder  92 , and a spring  93  as a cartridge pressing component, for convenience. Further,  FIG. 29  is a schematic sectional view of the pressing component  90  and cartridge P, as seen from the direction parallel to the moving direction of the tray, after the closing of the door. It shows the positional relationship between the pressing component  90  and cartridge P after the closing of the door.  FIG. 30  is a schematic sectional view of the pressing component  90  and cartridge P at a plane parallel to the moving direction of the tray, after the shifting of the cartridge P caused by the impacts and/or the like which occurred while the image forming apparatus was transported, with its door closed. It shows the positional relationship between the pressing component  90  and cartridge P after the shifting of the cartridge P.  FIG. 31  is a schematic sectional view of the pressing component  90  and cartridge P, at a plane perpendicular to the moving direction of the tray, after the cartridge P was shifted by the impacts and/or the like which occurred while the image forming apparatus was transported, with its door closed. 
         [0142]    Referring to  FIG. 29 , in terms of the lengthwise direction of the cartridge P, the cartridge engaging portion  95  of the pressing component  90  is disposed on the opposite side of the lateral plate  99  from the pressing portion  91 . Referring to  FIG. 31 , as the cartridge P is shifted due to the impacts and/or the like which occur during the transportation of the image forming apparatus, the portion  96  of contact of the cartridge P comes into contact with the pressing portion  91 . Therefore, even if the pressing component  90  is subjected to such force that acts in the direction indicated by an arrow mark, the engaging portion  95  of the pressing component  90  comes into contact with the lateral plate  99 , being enabled thereby to prevent the cartridge P from moving farther in the direction indicated by the arrow mark. That is, the pressing portion  90  can be prevented from becoming disengaged from the supporting portion  97 . Therefore, it is possible to regulate, with certainty, the movement of the cartridge P, which is caused by the impacts and/or the like. 
       (Miscellanies) 
       [0143]    1) In the embodiments of the present invention described above, the cartridge P which is removably installable in the apparatus main assembly  101  is a process cartridge of the integration type. However, these embodiments are not intended to limit the present invention in scope in terms of cartridge type. That is, the present invention is also applicable to a process cartridge of the separation type and a development cartridge. 
         [0144]    2) The number of cartridges P installable for an image forming operation does not need to be limited to four. It should be set as necessary. For example, in the case of an image forming apparatus for forming a monochromatic image, the number of process cartridge or development cartridge to be installed for an image formation is one. 
         [0145]    According to the present invention, the problem that when an image forming apparatus in which cartridges are present in their image formation positions is transported, the cartridges shift, can be prevented without reducing the image forming apparatus in usability. Thus, it is possible to protect the cartridges and image forming apparatus during the transportation of the apparatus. 
         [0146]    While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
         [0147]    This application claims priority from Japanese Patent Applications Nos. 195024/2012 and 163751/2013 filed Sep. 5, 2012 and Aug. 7, 2013, respectively, which are hereby incorporated by reference.