Patent Publication Number: US-9417604-B2

Title: Image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image forming apparatus configured to form images on recording media by using an electrophotographic image forming process. Examples of the image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (such as laser beam printer and LED printer), a facsimile machine, and a word processor. 
     2. Description of the Related Art 
     Hitherto, in image forming apparatus using an electrophotographic image forming process, there has been known a process cartridge system in which drums and developing units each housing a developing roller to affect the corresponding drums and each containing developer (toner) to be used for image formation are integrated with each other. Further, there has also been known a developing cartridge system in which the cartridge has only the developing units independently of the drums. Those cartridge systems allow users themselves to perform maintenance of the image forming apparatus without service engineers. Thus, those cartridge systems have been widely used in image forming apparatus. 
     Further, there has also been known a configuration in which a cartridge tray movable while supporting cartridges is arranged, and this cartridge tray is pulled out from an inside of a main body of the image forming apparatus so that an operation of replacing various cartridges can be performed. This configuration allows users to easily replace the process cartridges or the developing cartridges. 
     There have been proposed various configurations for suppressing scattering of toner or damage to components in the image forming apparatus including the cartridge tray, which may be caused by mounting the cartridge tray with a significant force (hereinafter referred to as “forceful mounting”). 
     For example, there has been proposed a configuration in which a frictional force imparting member is fixed in a main body of the image forming apparatus and brought into contact with the moving cartridge tray so that the force of the cartridge tray is reduced (FIG. 9 in Japanese Patent Application Laid-Open No. 2008-185830). 
     However, in the case where the frictional force imparting member is provided in the main body of the image forming apparatus, the cartridge tray cannot be sufficiently decelerated. As a result, the scattering of toner and the damage to components may not be sufficiently suppressed. 
     In view of the above-mentioned circumstances, there have been demands to sufficiently suppress the scattering of toner and the damage to components, which may be caused by forceful mounting of a cartridge tray, with a simple configuration. 
     SUMMARY OF THE INVENTION 
     According to a representative embodiment of the present invention, there is disclosed an image forming apparatus in which a process cartridge is removably mountable to a main body of the image forming apparatus, the image forming apparatus comprising: a containing member configured to contain the process cartridge and movable between an outside position outside the main body and an inside position inside the main body in a state of containing the process cartridge, the containing member being provided with a guided portion to be guided from an outside of the containing member; and a guiding portion provided in the main body and configured to guide a movement of the guided portion, wherein the guiding portion includes: a first guiding part configured to guide the guided portion when the containing member is moved from the outside position to the inside position by being inserted into the main body; and a second guiding part having a shape to return the guided portion toward the inside position when the containing member is further moved to a downstream side of the inside position in an inserting direction of the containing member. 
     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 
         FIG. 1  is an overall schematic sectional view of an image forming apparatus according to an embodiment of the present invention. 
         FIG. 2  is a sectional view of the image forming apparatus according to the embodiment of the present invention, for illustrating a state in which a cartridge tray is moved from an inside of a main body to an outside position. 
         FIG. 3  is a perspective view of the cartridge tray of the image forming apparatus according to the embodiment of the present invention. 
         FIG. 4  is a perspective view of the cartridge tray of the image forming apparatus according to the embodiment of the present invention as viewed from a side opposite to that in  FIG. 3 . 
         FIG. 5  is a schematic sectional view of a process cartridge according to the embodiment of the present invention. 
         FIG. 6  is a perspective view of the process cartridge according to the embodiment of the present invention. 
         FIG. 7  is a perspective view illustrating how the process cartridge according to the embodiment of the present invention is mounted into the cartridge tray. 
         FIG. 8  is a view of the cartridge tray in a state in which all the process cartridges according to the embodiment of the present invention are mounted. 
         FIG. 9  is a schematic sectional view of the main body, for illustrating a shape of a guiding portion configured to guide the cartridge tray in the embodiment of the present invention. 
         FIG. 10  is a view of a situation where the cartridge tray in the state illustrated in  FIG. 9  is being pushed into the main body in the embodiment of the present invention. 
         FIG. 11  is a view of a state in which a pair of guided portions is located in a positioning portion at the time of insertion of the cartridge tray in the embodiment of the present invention. 
         FIG. 12  is a view of a case where the cartridge tray is in an image formation mode in the embodiment of the present invention. 
         FIG. 13  is a schematic sectional view illustrating movement of the cartridge tray that is forcefully mounted into the main body in the embodiment of the present invention. 
         FIG. 14A  is a partial perspective view of a state in which the cartridge tray that is forcefully mounted into an image forming apparatus according to another embodiment of the present invention is held in contact with a returning mechanism. 
         FIG. 14B  is a partial perspective view of a state in which the cartridge tray is returned to the positioning portion after the contact with the returning mechanism. 
         FIG. 15  is a view illustrating a returning mechanism that interlocks with an opening/closing door of an image forming apparatus according to still another embodiment of the present invention. 
         FIGS. 16A, 16B, and 16C  are each a partial sectional view illustrating movement of the returning mechanism that interlocks with the opening/closing door in the embodiment illustrated in  FIG. 15 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Now, embodiments of the present invention will be described in detail with reference to the drawings. 
     First Embodiment 
     &lt;Overall Configuration of Image Forming Apparatus&gt; 
     An overall configuration of an image forming apparatus according to an embodiment of the present invention will be described. 
       FIG. 1  is an overall schematic sectional view of the image forming apparatus according to the embodiment of the present invention. The image forming apparatus illustrated in  FIG. 1  includes process cartridges PY, PM, PC, and PK each including a drum  1 , and a main body  100  constructed such that those process cartridges PY, PM, PC, and PK can be mounted thereinto and removed therefrom. 
     In the following description, a rotation axis direction of the drum  1  is referred to as a longitudinal direction. Further, a side on which an opening/closing door  34  is arranged is referred to as a front side (front surface side). A rear side refers to a side opposite thereto, and front and rear directions refer to a direction from the front side toward the rear side of the main body  100 , and a direction opposite thereto. Further, the left and the right correspond to the left and the right as viewed from the front side of the main body  100 . Further, the process cartridges PY, PM, PC, and PK are collectively described as process cartridges P. 
     As illustrated in  FIG. 1 , the main body  100  includes a cartridge tray  13  (containing member). This cartridge tray  13  includes four cartridge containing portions  13   f  configured to respectively contain the four process cartridges PY, PM, PC, and PK. From the rear side toward the front side of the main body  100 , the four process cartridges PY, PM, PC, and PK are arrayed in a horizontal direction. The process cartridges P are the same electrophotographic process mechanisms that are different from each other only in color of contained developer. The four drums  1  that are arrayed in the horizontal direction are each rotated in a direction of the arrow R in  FIG. 1  by drive units (not shown) in the main body  100 . 
     In the main body  100 , a scanner unit  3  is provided on a lower side in a gravity direction of the process cartridges P. This scanner unit  3  outputs laser beams L modulated in accordance with image information. Then, the laser beams L are radiated onto drum surfaces of the drums  1  of the process cartridges P through exposure window portions  10  that are formed through the process cartridges P. An intermediate transfer belt unit  6  as a transfer member is arranged above the process cartridges P. The intermediate transfer belt unit  6  includes a driving roller  6   b , a secondary transfer opposing roller  6   c , a tension roller  6   d , and a flexible dielectric endless belt  6   a  that is stretched around those rollers. 
     The endless belt  6   a  extends substantially in the same direction as a moving direction of the cartridge tray  13 , and also in the longitudinal direction of the drum  1 . 
     (Overall Operation of Image Forming Apparatus) 
     Next, an operation of forming a full-color image will be described. 
     The drums  1  of the process cartridges P are each driven to rotate at a predetermined speed. The endless belt  6   a  is driven to rotate in a direction of the arrow H in  FIG. 1  at a speed in accordance with the speed of the drums  1 . In synchronization with the driving, in each of the cartridges P, a charging roller  2  as a charging unit uniformly charges the surface of the drum  1  with a predetermined polarity and electric potential at a predetermined control timing. The scanner unit  3  performs scanning exposure on the surfaces of the drums  1  with the laser beams L that are modulated in accordance with image signals of respective colors. With this, electrostatic latent images of the image signals of corresponding colors are formed on the surfaces of the drums  1 . The electrostatic latent images thus formed are developed by developing rollers  40  as developing units. 
     Then, those developer images are primarily transferred onto the endless belt  6   a  at primary-transfer nip portions as contact portions between the drums  1  and the endless belt  6   a . Primary transfer rollers  12  are each held in press-contact with the drum  1  through intermediation of the endless belt  6   a  to form the primary-transfer nip portion. 
     In this way, on the endless belt  6   a , a four-full-color unfixed developer image is formed by combining a color Y, a color M, a color C, and a color K. In each of the process cartridges P, untransferred residual toner remaining on the drum surface of the drum  1  after the primary transfer of the developer image onto the endless belt  6   a  is removed by a cleaning blade  16  as a cleaning unit, and sent into a waste toner collecting portion. 
     Meanwhile, a feed roller  18  is driven at predetermined control timings. With this, sheet-like recording media S (transferred materials) received and stacked in a sheet feeding cassette  17  are fed. Then, at a predetermined timing, the recording medium S is introduced by a registration roller pair  19  into a secondary-transfer nip portion as a contact portion between the endless belt  6   a  and the secondary transfer roller  29 . 
     A secondary transfer bias having a polarity reverse to the charging polarity of the developer and having a predetermined electric potential is applied to the secondary transfer roller  29  at a predetermined timing. With this, the four-color-superimposed developer image on the endless belt  6   a  is secondarily transferred onto a surface of the recording medium S while the recording medium S is nipped and conveyed through the secondary-transfer nip portion. The recording medium S, which passes through the secondary-transfer nip portion, is separated from the surface of the endless belt  6   a  and is introduced into a fixing device  20 . Then, the recording medium S is heated and pressurized in a fixing nip portion. With this, the above-mentioned colors of the developer images are mixed with each other, and the developer images are fixed onto the recording medium S. Then, the recording medium S is fed out from the fixing device  20 , and delivered as a full-color image by a delivery roller pair  23  onto a delivery tray  24 . 
     (General Configuration of Cartridge Tray) 
     Next, the cartridge tray  13  movable between an inside position (storage position) on the inside of the main body  100  and an outside position (pullout position) on the outside of the main body  100  while supporting the process cartridges P will be described. Note that, the inside position refers to a position of the cartridge tray  13  that is stored in the main body  100 , and the outside position refers to a position of the cartridge tray  13  that is pulled out so that the process cartridges P can be replaced. 
       FIG. 2  is a sectional view of a state in which the cartridge tray  13  is moved from the inside of the main body  100  to the outside position. As illustrated in  FIG. 2 , the cartridge tray  13  can be linearly moved with respect to (pushed into or pulled out from) the main body  100  substantially in the horizontal direction (directions of the arrows D 1  and D 2 ). With this, the cartridge tray  13  can be moved to the inside position in the inside of the main body  100  (position illustrated in  FIG. 1 ), or to the outside position corresponding to the position of the cartridge tray  13  that is pulled out to the outside of the main body  100  (position illustrated in  FIG. 2 ). 
     Further, in the state in which the cartridge tray  13  is located in the outside position, the process cartridges P are mounted into the cartridge tray  13  substantially in the gravity direction (direction of the arrow C in  FIG. 2 ) by a user. The process cartridges P thus mounted are arranged so that longitudinal directions thereof are orthogonal to the moving direction of the cartridge tray  13 . Note that, the four process cartridges PY, PM, PC, and PK are arrayed in the moving direction of the cartridge tray  13 . 
     The process cartridges P are moved into the main body  100  together with the cartridge tray  13  in the state of being mounted into the cartridge tray  13 . Then, when an insertion opening for the cartridge tray  13  is closed by the opening/closing door  34  in the state in which the cartridge tray  13  is moved into the main body  100 , all the process cartridges P are positioned to predetermined positions in the main body  100 . 
     With the configuration described above, the four process cartridges P can be collectively mounted into the main body  100 , and the four process cartridges P can be collectively pulled out to the outside of the main body  100 . Thus, operability at the time of replacement of the process cartridges P is more excellent than that in a case where a configuration of independently mounting the process cartridges P into the main body  100  is employed. 
     (Specific Configuration of Cartridge Tray) 
     Next, a configuration of the cartridge tray  13  will be described in detail.  FIG. 3  is a perspective view of the cartridge tray  13  of the image forming apparatus according to the embodiment.  FIG. 4  is a perspective view of the cartridge tray  13  as viewed from a side opposite to that in  FIG. 3 . 
     As illustrated in  FIGS. 3 and 4 , at four corners of the cartridge tray  13 , a pair of guided portions  13   a  and a pair of guided portions  13   b  to be guided along guiding portions of the main body  100  described below are formed. Those pairs of guided portions  13   a  and  13   b  are each formed into a columnar shape projecting outward from side surfaces of the cartridge tray  13 . 
     Further, in the cartridge tray  13 , the cartridge containing portions  13   f  configured to allow the process cartridges P to be mounted thereinto are formed in an array. At both end portions in the longitudinal direction of each of the cartridge containing portions  13   f , guiding portions  13   h ,  13   i ,  13   j , and  13   k  configured to allow the process cartridges P to be mounted into the cartridge tray  13  are formed. The guiding portions  13   h ,  13   i ,  13   j , and  13   k  each extend in a vertical direction. In addition, positioning portions  13   p  and  13   q  configured to position the process cartridges P with respect to the cartridge tray  13  are formed respectively between the guiding portions  13   h  and  13   i  and between the guiding portions  13   j  and  13   k . The positioning portions  13   p  and  13   q  are each formed into a V-shape. 
     (Configuration of Process Cartridge) 
     Next, the process cartridge P to be mounted into the cartridge tray  13  will be described. 
       FIG. 5  is a schematic sectional view of the process cartridge P according to the embodiment.  FIG. 6  is a perspective view of the process cartridge P according to the embodiment.  FIG. 7  is a perspective view illustrating how the process cartridge P according to the embodiment is mounted into the cartridge tray  13 . 
     As illustrated in  FIG. 5 , the process cartridge P includes a photosensitive unit  8  and a developing unit  4 . Further, the photosensitive unit  8  includes the drum  1 , a photosensitive frame  8   a  configured to support the drum  1 , the charging roller  2 , the cleaning blade  16 , and a waste toner collecting portion  8   b  configured to collect the developer (hereinafter referred to as “toner”) removed by the cleaning blade  16 . Further, the developing unit  4  includes the developing roller  40 , a developing frame  4   a  configured to support the developing roller  40 , a toner supply roller  43 , and a developing blade  44 . In addition, the developing unit  4  also includes a toner containing portion  4   b  configured to contain toner T to be used for image formation, and a conveying member  48  configured to supply the toner T in the toner containing portion  4   b.    
     The toner T in the toner containing portion  4   b  is supplied to the toner supply roller  43  by the conveying member  48 . Then, the toner supply roller  43  and the developing blade  44  that is held in press-contact with an outer periphery of the developing roller  40  causes the toner T to be applied to the outer periphery of the developing roller  40  and to be electrically charged. Then, a developing bias is applied from the main body  100  to the developing roller  40  so that the toner T adheres to the latent image formed on the drum  1  to form a toner image. After the toner image formed on the drum  1  is transferred onto the endless belt  6   a , the toner T remaining on the surface of the drum  1  is removed by the cleaning blade  16 , and collected into the waste toner collecting portion  8   b.    
     Note that, in a case where the toner T in the toner containing portion  4   b  is consumed, the user only has to replace the process cartridge P to perform printing again. 
     As illustrated in  FIG. 6 , at ends of the photosensitive unit  8  and the developing unit  4  on one side, coupling members  47  and  45  configured to receive a driving force from the main body  100  are supported to be turnable. The coupling member  47  is formed at one end of the drum  1  to receive the driving force from the main body  100 , to thereby rotate the drum  1 . Further, the driving force from the main body  100 , which is received by the coupling member  45 , is transmitted to the developing roller  40 , the toner supply roller  43 , and the conveying member  48  through intermediation of an intermediate gear (not shown) to rotate those components (refer to  FIG. 5 ). 
     An outer periphery of the coupling member  45  is covered with a cylindrical rib. With this, an engagement portion  71   a  is formed on a side cover  71  fixed to an outside of the developing frame  4   a . The coupling member  45  is configured to be turnable about the engagement portion  71   a . Further, as illustrated in  FIG. 7 , an engagement portion  70   a  is formed also on a side opposite to the engagement portion  71   a . This engagement portion  70   a  is formed on a side cover  70 . 
     Further, hole portions  8   c  and  8   d  configured to support the engagement portions  71   a  and  70   a  are formed through the photosensitive frame  8   a . The hole portions  8   c  and  8   d  formed through the photosensitive frame  8   a  are engaged with the engagement portions  71   a  and  70   a  provided on the developing unit  4 . With this, the photosensitive unit  8  and the developing unit  4  are coupled to each other. 
     Specifically, the engagement portions  71   a  and  70   a  are configured to be turnable respectively about the hole portions  8   c  and  8   d , and hence the developing unit  4  can be moved with respect to the photosensitive unit  8 . In other words, the developing roller  40  is configured to be movable with respect to the drum  1 . 
     As illustrated in  FIGS. 5 to 7 , a spring  9  as a biasing member is interposed between the photosensitive unit  8  and the developing unit  4 . This spring  9  generates a predetermined pressure for pressing the developing roller  40  against the drum  1 . 
     As illustrated in  FIG. 6 , an outer periphery of the coupling member  47  is covered with a cylindrical rib. With this, a positioned portion  8   e  is formed. Further, as illustrated in  FIG. 7 , on a side opposite to the positioned portion  8   e , another positioned portion  8   f  is formed of a cylindrical projection. 
     Further, as illustrated in  FIG. 6 , a rotation regulated portion  8   g  is arranged below the positioned portion  8   e . As illustrated in  FIG. 7 , a rotation regulated portion  8   h  is arranged below the positioned portion  8   f . The rotation regulated portions  8   g  and  8   h  are each formed into a shape of a substantially rectangular column extending in the same direction as a mounting direction of the process cartridge P into the cartridge tray  13 , which is indicated by the arrow C. 
     The process cartridge P to be inserted into the cartridge tray  13  is positioned by those positioned portions  8   e  and  8   f  and rotation regulated portions  8   g  and  8   h.    
     Further, columnar regulated portions  8   i ,  4   j ,  8   j , and  4   k  are formed below the rotation regulated portions  8   g  and  8   h . The regulated portions  8   i  and  8   j  and the regulated portions  4   j  and  4   k  are provided on the photosensitive unit  8  and the developing unit  4 , respectively, in a manner of sandwiching the drum  1 . 
     (Mounting of Process Cartridge) 
     With reference to  FIGS. 7 and 8 , how the process cartridges P are mounted into the cartridge tray  13  will be described.  FIG. 8  illustrates the cartridge trays  13  in a state in which all the process cartridges P are mounted. 
     The process cartridges PY, PM, PC, and PK are mounted respectively into the cartridge containing portions  13   f  formed at four positions in the cartridge tray  13  (refer to  FIGS. 3 and 4 ). The user mounts the process cartridges P in the direction of the arrow C substantially corresponding to the gravity direction. 
     In order to mount the process cartridge P, the user first mounts the regulated portions  8   j ,  4   k ,  8   i , and  4   j  provided on both end portions of the process cartridge P along the guiding portions  13   k ,  13   j ,  13   i , and  13   h  of the cartridge tray  13 . Next, the user mounts the rotation regulated portions  8   g  and  8   h  along the guiding portions  13   i  and  13   k  (refer to  FIGS. 3 and 4 ). In this way, the process cartridge P is guided along the guiding portions  13   k ,  13   j ,  13   i , and  13   h  and mounted into the cartridge tray  13 . 
     When the process cartridges P are mounted into the cartridge tray  13 , the positioned portions  8   e  and  8   f  are brought into contact with the positioning portions  13   p  and  13   q  formed in the cartridge tray  13 . The positioning portions  13   p  and  13   q  are each formed into a V-shape, and hence, when the positioning portions  13   p  and  13   q  are brought into contact with the columnar positioned portions  8   e  and  8   f , the process cartridge P can be positioned in the mounting direction of the process cartridge P. Further, the rotation regulated portions  8   h  and  8   g  are brought into contact with side surfaces of the guiding portions  13   k  and  13   i . With this, a posture in a turning direction of the process cartridge P can be determined. The positioned portions  8   e  and  8   f  and the rotation regulated portions  8   h  and  8   g  allow the process cartridge P to be positioned in the cartridge tray  13 . 
     Note that, the regulated portions  8   j ,  4   k ,  8   i , and  4   j  reach retreat portions  13   k   1 ,  13   j   1 ,  13   i   1 , and  13   h   1  (refer to  FIGS. 3 and 4 ) that are formed on a depth side of the guiding portions  13   k ,  13   j ,  13   i , and  13   h , respectively. At those positions, the regulated portions  8   j ,  4   k ,  8   i , and  4   j  are not held in contact with the cartridge tray  13 , and hence do not hinder positioning of the process cartridge P with respect to the cartridge tray  13 . 
     (Configuration for Mounting Toner Cartridge) 
     Next, how the cartridge tray  13  according to the embodiment is mounted into the main body  100  will be described. 
       FIG. 9  is a schematic sectional view of the main body  100 , for illustrating a shape of a guiding portion configured to guide the cartridge tray  13 . Note that, in the embodiment, configurations on the left and right are the same as each other, and hence only one side (right-hand side) will be described with reference to  FIG. 9 . 
     As illustrated in  FIG. 9 , on an inner wall surface of a frame  14  of the main body  100 , there is fixed a guiding portion  14 R configured to guide movement of the cartridge tray  13  by allowing the guided portions  13   a  and  13   b  of the cartridge tray  13  to pass through an inside thereof. The guiding portion  14 R includes a first guiding part  14 S configured to guide the movement of the cartridge tray  13 , a positioning portion  14 T (first positioning portion), another positioning portion  14 U (second positioning portion), and a second guiding part  14 V. 
     The first guiding part  14 S is configured to guide the cartridge tray  13  from the position of the cartridge tray  13  that is pulled out to the outside of the main body  100  to the position of the cartridge tray  13  that is stored in the main body  100 . In other words, the first guiding part  14 S is formed to extend substantially in the horizontal direction from a vicinity of the insertion opening of the main body  100  (vicinity of the opening/closing door  34 ) to the depth side. This first guiding part  14 S is provided by forming a recessed portion (substantially C-shape in cross section) in the inner wall surface of the frame  14 . 
     The positioning portion  14 T is a positioning portion configured to position the cartridge tray  13  in a transverse direction (insertion direction) of the cartridge tray  13 . The positioning portion  14 T is provided by forming a recessed portion (first recessed portion) on a lower side in the gravity direction of the first guiding part  14 S. The positioning portion  14 U is a positioning portion configured to position the cartridge tray  13  to an image formation position at the time of image formation. The positioning portion  14 U is provided by forming a recessed portion (second recessed portion) having an inverted V-shape above the positioning portion  14 T. The cartridge tray  13  is positioned when a part of the guided portion  13   a  enters the positioning portions  14 T or  14 U. 
     Further, the second guiding part  14 V is formed in the guiding portion  14 R to decelerate the cartridge tray  13  in a case where the cartridge tray  13  is forcefully mounted into the main body  100 , and to return the cartridge tray  13  to a predetermined position. The configuration of this part will be described in detail below. 
     (Operation of Mounting Cartridge Tray) 
     Next, an operation of mounting the cartridge tray  13  into the main body  100  will be described.  FIG. 10  is a view of a situation where the cartridge tray  13  in the state illustrated in  FIG. 9  is being pushed into the main body  100 .  FIGS. 11 and 12  are each a view of a state in which the cartridge tray  13  is pushed in the main body  100 .  FIG. 11  is a view of a state in which the guided portion  13   a  is located in the positioning portion  14 T at the time of insertion of the cartridge tray  13 .  FIG. 12  is a view of a case where the cartridge tray  13  is in an image formation mode. 
     In the state illustrated in  FIG. 9 , the cartridge tray  13  is moved in the main body  100  while the guided portion  13   a  thereof is guided along the first guiding part  14 S of the guiding portion  14 R, and enters the state illustrated in  FIG. 10 . Subsequently, as illustrated in  FIG. 11 , the guided portion  13   a  comes to the positioning portion  14 T. Then, the movement is completed. 
     After the completion of the movement of the cartridge tray  13 , when the opening/closing door  34  is closed, a pressing member (not shown) presses the cartridge tray  13  upward so as to bring the guided portion  13   a  into contact with the positioning portion  14 U. With this, the cartridge tray  13  is positioned to the image formation position. At this time, as illustrated in  FIG. 12 , the drum  1  of each of the process cartridges P positioned in the cartridge tray  13  is brought into contact with the endless belt  6   a.    
     (Configuration of Second Guiding Part) 
     Next, the second guiding part  14 V of the guiding portion  14 R will be described. 
       FIG. 13  is a schematic sectional view illustrating the movement of the cartridge tray  13  that is forcefully mounted into the main body  100 . 
     As illustrated in  FIG. 13 , the second guiding part  14 V is formed on a downstream side in the inserting direction of the cartridge tray  13  with respect to the positioning portion  14 T of the guiding portion  14 R. In addition, the second guiding part  14 V is extended on the downstream side in the inserting direction with respect to an outermost position G (refer to  FIG. 11 ) of the guided portion  13   a  in a state in which the guided portion  13   a  of the cartridge tray  13  is engaged with the positioning portion  14 T. Further, the second guiding part  14 V is extended upward in the gravity direction with respect to the first guiding part  14 S. 
     With this configuration, even when the cartridge tray  13  is forcefully mounted in the direction of the arrow D 1 , a moving speed of the cartridge tray  13  is reduced by its own weight while the cartridge tray  13  is moved in the second guiding part  14 V. Specifically, as illustrated in  FIG. 13 , when the guided portion  13   a  of the forcefully mounted cartridge tray  13  passes over the positioning portion  14 T and reaches the second guiding part  14 V, the moving speed of the cartridge tray  13  is reduced. Then, the moving direction of the cartridge tray  13  is switched to a direction of the arrow W, and the cartridge tray  13  is stopped when the guided portion  13   a  comes to the positioning portion  14 T. In other words, the guided portion  13   a  is lowered along the second guiding part  14 V by weights of the cartridge tray  13  and the process cartridges P. In this way, the cartridge tray  13  is moved toward the positioning portion  14 T (storage position, inside position). 
     In other words, the second guiding part  14 V has a shape to return the guided portion  13   a  toward the inside position when the cartridge tray  13  has further been moved to the downstream side of the inside position in the inserting direction of the cartridge tray  13 . 
     Furthermore, in the embodiment, there is provided an abutting portion  14 V 1  (abutting member) configured to abut against the cartridge tray  13  when the guided portion  13   a  enters the second guiding part  14 V, to thereby limit the movement of the cartridge tray  13 . With this, the forcefully mounted cartridge tray  13  is prevented from running up along the second guiding part  14 V so that components stored in the cartridge tray  13 , such as the drums  1 , can be prevented from interfering with the endless belt  6   a . In the embodiment, the guided portion  13   a  of the cartridge tray  13  is brought into contact with the abutting portion  14 V 1  on the downstream side in the inserting direction of the cartridge tray  13  with respect to the positioning portion  14 T in the state in which the guided portion  13   a  is positioned at the positioning portion  14 T ( FIG. 11 ). 
     Second Embodiment 
     Next, an image forming apparatus according to another embodiment of the present invention will be described. Note that, the basic configuration of the second embodiment is the same as that of the first embodiment, and hence only differences from the first embodiment will be described below. Further, the same or similar parts as those in the first embodiment are denoted by the same reference symbols to omit redundant description. 
     In the first embodiment, the guided portion  13   a  of the forcefully mounted cartridge tray  13  is moved to the positioning portion  14 T only by gravity. In the embodiment, in order to more reliably perform the positioning, there is provided a returning mechanism  25  configured to return the guided portion  13   a  to the positioning portion  14 T. 
       FIGS. 14A and 14B  are each a partial perspective view of the image forming apparatus according to the embodiment, which includes the returning mechanism  25 .  FIG. 14A  is a view of a state in which the forcefully mounted cartridge tray  13  is held in contact with the returning mechanism  25 , and  FIG. 14B  is a view of a state in which the cartridge tray  13  is returned to the positioning portion  14 T after the contact with the returning mechanism  25 . 
     As illustrated in  FIGS. 14A and 14B , the returning mechanism  25  includes a contact member  26  to be brought into contact with the cartridge tray  13 , and a support member  28  fixed to the frame  14  and configured to support the contact member  26  in a slidable manner. The contact member  26  includes rib-shaped parts  26   a  so as to be slidable along groove portions  28   a  formed in the support member  28 . Further, the returning mechanism  25  also includes a pressing member  27  fixed at one end portion to the contact member  26  and configured to press the contact member  26 . 
     When the guided portion  13   a  of the forcefully mounted cartridge tray  13  is further moved to the downstream side of the positioning portion  14 T in the inserting direction of the cartridge tray  13 , as illustrated in  FIG. 14A , the cartridge tray  13  is brought into contact with the contact member  26 . With this, the pressing member  27  is compressed to absorb impact. A restorative force of the compressed pressing member  27  and the own weight of the cartridge tray  13  cause the guided portion  13   a  of the cartridge tray  13  to be moved to the positioning portion  14 T (direction of the arrow W in  FIG. 14B ). 
     As described in the embodiment, the second guiding part  14 V and the returning mechanism  25  are used in combination. With this, the impact to the cartridge tray  13  at the time of the forceful mounting can be reduced, and the guided portion  13   a  of the cartridge tray  13  can be more reliably moved to the positioning portion  14 T. 
     Third Embodiment 
     Next, an image forming apparatus according to another embodiment of the present invention will be described. Note that, the basic configuration of the third embodiment is the same as that of the first embodiment, and hence only differences from the first embodiment will be described below. Further, the same or similar parts as those in the first embodiment are denoted by the same reference symbols to omit redundant description. 
     In the embodiment, a returning mechanism  30  (pressing mechanism) configured to interlock with the opening/closing door  34  so as to return the forcefully mounted cartridge tray  13  to a predetermined position is used. 
     (Configuration of Returning Mechanism) 
       FIG. 15  is a view of the opening/closing door  34 , the frame  14 , and the returning mechanism  30 , for illustrating the returning mechanism  30  that interlocks with the opening/closing door  34 . 
     As illustrated in  FIG. 15 , the returning mechanism  30  includes a link member  31 , a sliding member  32 , and a returning member  33 . The link member  31  includes a hole portion  31   a  and a protruding portion  31   b . The hole portion  31   a  is engaged with a protruding portion  34   a  formed on the opening/closing door  34 , and the protruding portion  31   b  of the link member  31  is engaged with a hole portion  32   a  formed through the sliding member  32 . 
     The sliding member  32  is supported to be movable substantially in the horizontal direction with respect to the frame  14 , and includes the hole portion  32   a  and a protruding portion  32   b . The returning member  33  includes a hole portion  33   a , a cutout portion  33   b , and a contact portion  33   c . The hole portion  33   a  of the returning member  33  is supported to be turnable by a protruding portion  14   k  formed on the frame  14 . Further, the protruding portion  32   b  of the sliding member  32  is engaged with the cutout portion  33   b  of the returning member  33 . 
     (Movement of Returning Mechanism) 
     Next, movement of the returning mechanism  30  will be described. 
       FIGS. 16A, 16B, and 16C  are each a partial sectional view illustrating the movement of the returning mechanism  30  that interlocks with the opening/closing door  34 . In those drawings, components other than the cartridge tray  13 , the opening/closing door  34 , the returning mechanism  30 , the frame  14 , and the process cartridges P are omitted.  FIG. 16A  is a view of a state in which the guided portion  13   a  of the forcefully mounted cartridge tray  13  is stopped halfway in the second guiding part  14 V without returning to the positioning portion  14 T.  FIG. 16B  is a view of a state in which the opening/closing door  34  in the state of  FIG. 16A  starts to be closed.  FIG. 16C  is a view of a state in which the opening/closing door  34  in the state of  FIG. 16B  is further closed. 
     When the opening/closing door  34  in the state of  FIG. 16A  is closed in a direction of the arrow Z as illustrated in  FIG. 16B , along therewith, the sliding member  32  is moved in a direction of the arrow V, and the returning member  33  is moved in a direction of the arrow X. With this, the contact portion  33   c  of the returning member  33  is brought into contact with the cartridge tray  13 . When the opening/closing door  34  is further closed in the direction of the arrow Z, along therewith, as illustrated in  FIG. 16C , the guided portion  13   a  starts to be moved toward the positioning portion  14 T. Movement of the guided portion  13   a  can be assisted until immediately before the guided portion  13   a  comes to the positioning portion  14 T ( FIG. 16C ). 
     As described above, when the second guiding part  14 V and the returning mechanism  30  are used in combination, the cartridge tray  13  can be more reliably located in the positioning portion  14 T in conjunction with the opening/closing door  34 . 
     Note that, in the first to third embodiments described above, the second guiding part  14 V is formed of a flat surface extended in a direction opposite to the gravity direction, but the present invention is not limited thereto. For example, there may be employed a curved surface extended in the direction opposite to the gravity direction, or a combination of the curved surface and the flat surface. 
     Further, advantages of the first to third embodiment described above can be summarized as follows. According to the embodiments described above, in the case where the containing member is mounted into the main body, the guided portion of the containing member is guided along the first guiding part along with the movement of the containing member between the outside position and the inside position. Then, the second guiding part is formed into such a shape that the guided portion is biased to cause the containing member to be returned toward the inside position when the containing member is moved further from the inside position to the downstream side in the inserting direction of the containing member. With this, when the containing member is forcefully mounted, the containing member can be effectively decelerated. As a result, scattering of toner or damage to components can be suppressed. 
     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. 
     This application claims the benefit of Japanese Patent Application No. 2014-110961, filed May 29, 2014, which is hereby incorporated by reference herein in its entirety.