Patent Publication Number: US-11640135-B2

Title: Image forming apparatus including developing device supporting structure having guide groove

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/238,337, filed Apr. 23, 2021, now U.S. Pat. No. 11,237,515, which is a continuation of U.S. patent application Ser. No. 16/876,241, filed May 18, 2020, now U.S. Pat. No. 10,996,618, which is a continuation of U.S. patent application Ser. No. 16/401,773, filed May 2, 2019, now U.S. Pat. No. 10,671,014, which is a continuation of U.S. patent application Ser. No. 15/897,937, filed Feb. 15, 2018, now U.S. Pat. No. 10,281,870, which is a continuation of U.S. patent application Ser. No. 15/397,474, filed Jan. 3, 2017, now U.S. Pat. No. 9,897,969, which is a continuation of U.S. patent application Ser. No. 15/068,181, filed Mar. 11, 2016, now U.S. Pat. No. 9,541,893, which is a continuation of U.S. patent application Ser. No. 14/610,800, filed Jan. 30, 2015, now U.S. Pat. No. 9,285,759, all of which further claims priority from Japanese Patent No. 2014-017519, filed on Jan. 31, 2014, the contents of all of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Aspects of the present invention relate to an image forming apparatus including a belt unit, a drum unit, and a developing device unit. 
     BACKGROUND 
     A known image forming apparatus includes a developing device unit, and a belt unit and a drum unit that are disposed above the developing device unit. To prevent the developing device unit from interfering with the drum unit when the developing device unit is drawn, the image forming apparatus is configured to move the drum unit upward and downward in response to the opening and closing movements of an upper cover of the image forming apparatus. After the upper cover is opened to retract the drum unit upward, a front cover of the image forming apparatus is opened to withdraw the developing device unit. 
     SUMMARY 
     In the structure of the known image forming apparatus, the upper cover and the front cover need to be opened to withdraw the developing device unit, which is troublesome. 
     One or more aspects of the disclosure are to provide an image forming apparatus in which a developing device unit may be readily withdrawn. 
     According to one or more aspects of the disclosure, an image forming apparatus may include a main casing, an opening-closing member, a belt unit, a drum unit, a developing device unit, and an interlock mechanism. The main casing may have an opening on a side thereof. The opening-closing member may be configured to open and close the opening on the side of the main casing, to be pivotable relative to the main casing, and to move between an open position in which the opening is opened and a closed position in which the opening is closed. The belt unit may include an endless belt, may be disposed in the main casing and may be configured to move between a first position and a second position positioned above the first position. The drum unit may include a plurality of photosensitive drums, may be disposed below the belt unit and may be configured to move between a third position and a fourth position positioned above the third position. The developing device unit may be disposed below the belt unit, may include a plurality of developing rollers each of which corresponds to a respective one of the plurality of photosensitive drums, and may be configured to move, through the opening, in an arrangement direction in which the plurality of developing rollers is arranged. The interlock mechanism may be configured such that in response to a movement of the opening-closing member from the closed position to the open position, the belt unit moves from the first position to the second position and the drum unit moves from the third position to the fourth position, and in response to a movement of the opening-closing member from the open position to the closed position, the belt unit moves from the second position to the first position and the drum unit moves from the fourth position to the third position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects of the present invention will become more apparent and more readily appreciated from the following description of illustrative embodiments of the present invention taken in conjunction with the attached drawings, in which: 
         FIG.  1    is a sectional view of a color multifunction device in an illustrative embodiment according to one or more aspects of the disclosure; 
         FIG.  2    is a sectional view of the color multifunction device with a front cover closed, depicting a developing device unit and a drum unit are removed from the color multifunction device; 
         FIG.  3    is a sectional view of the color multifunction device with the front cover open, depicting the developing device unit and the drum unit are removed from the color multifunction device; 
         FIG.  4    is a side view of the drum unit; 
         FIG.  5    is a sectional view of the color multifunction device with the front cover open; 
         FIG.  6    is a sectional view of the color multifunction device from which the drum unit is withdrawn; 
         FIG.  7    is a sectional view of the color multifunction device taken along a plane perpendicular to a front-rear direction; 
         FIG.  8 A  is a sectional view of a developing device supporting frame; 
         FIG.  8 B  is side view of the developing device unit; 
         FIG.  9    is a sectional view of the color multifunction device from which the developing device unit is withdrawn; 
         FIG.  10 A  depicts a relationship between a developing roller supporting portion and the front cover when the front cover is closed; and 
         FIG.  10 B  is depicts a relationship between the developing roller supporting portion and the front cover when the front cover is open. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative embodiment will be described with reference to the accompanying drawings. First, overall structures of an image forming apparatus, e.g., a color multifunction device  1 , and then features of the disclosure will be described. 
     Hereinafter, description will be made with reference to directions that are defined in conjunction with an orientation in which a user uses the color multifunction device  1 . More specifically, left and right sides of  FIG.  1    are defined as front/forward and rear/back sides, respectively. The front and back sides of the sheet of  FIG.  1    are defined as right and left sides, respectively. The top-bottom direction in  FIG.  1    is defined as the vertical direction. 
     General Structure of Color Multifunction Device 
     As depicted in  FIG.  1   , the color multifunction device  1  mainly includes a main casing  2 , and a flatbed scanner  3  disposed above the main casing  2 . The color multifunction device  1  mainly includes, in the main casing  2 , a sheet supply unit  4  configured to supply a recording sheet, e.g., a sheet P, and an image forming unit  5  configured to form an image on the supplied sheet P. 
     The main casing  2  has an opening  2 A at a front portion thereof (refer to  FIG.  3   ). The main casing  2  includes an opening-closing member, e.g., a front cover  24 , configured to cover a front portion of the opening  2 A. The front cover  24  is configured to pivot on a pivot shaft  24 A disposed at a lower portion of the front cover  24 , so that the opening  2 A may be opened or closed. In other words, the front cover  24  is configured to move between an open position (e.g., a position as depicted in  FIG.  3   ) in which the front cover  24  opens or uncovers the opening  2 A and a closed position (e.g., a position as depicted in  FIG.  1   ) in which the front cover  24  covers or closes the opening  2 A. The pivot shaft  24 A is disposed below a developing device unit  7  (described below). 
     The flatbed scanner  3  is a document reading device having a known structure. The flatbed scanner  3  is configured to irradiate a document with light to read an image and generate image data for duplication. The flatbed scanner  3  is disposed with a space between the scanner  3  and a discharge tray  22 . 
     The sheet supply unit  4  mainly includes a sheet cassette  41  disposed at a lower portion of the main casing  2  and configured to be removably attached to the main casing  2 , a pickup roller  42  and a separation roller  43  disposed above a rear portion of the sheet cassette  41 . The sheets P in the sheet cassette  41  are fed by the pickup roller  42 , and separated one by one by the separation roller  43 . Then, the sheet P is supplied to the image forming unit  5  (e.g., between an intermediate transfer belt  91  and a second transfer roller  93 ). 
     The image forming unit  5  mainly includes a drum unit  6 , a developing device unit  7 , a scanner unit  8 , a belt unit  9 , and a fixing unit  10 . 
     The drum unit  6  is disposed below the belt unit  9 . The drum unit  6  mainly include, in a supporting member, e.g., a drum supporting frame  60 , that constitutes an outer frame of the unit  6 , a plurality of, e.g., four, photosensitive drums  61  arranged along the front-rear direction, chargers  62 , each corresponding to a respective one of the photosensitive drums  61 , and a first cleaning roller  63  disposed in front of the frontmost photosensitive drum  61  among the photosensitive drums  61 . 
     The first cleaning roller  63  is configured to remove toner remaining on the intermediate transfer belt  91  (described below). 
     The developing device unit  7  is disposed below the drum unit  6 . The developing device unit  7  mainly includes, in a developing device supporting frame  70  that constitutes an outer frame of the unit  7 , a plurality of, e.g., four, developing devices  71 , each corresponding to a respective one of the photosensitive drums  61 . 
     Each of the developing devices  71  mainly includes a developing roller  71 A opposing the corresponding photosensitive drum  61 , a supply roller  71 B configured to supply toner to the developing roller  71 A, a toner chamber (reference numeral omitted) that accommodates toner, and an agitator (reference numeral omitted) disposed in the toner chamber. In each of the developing devices  71 , toner in the toner chamber is supplied to the supply roller  71 B by the agitator that is rotating. Further, the toner is supplied from the supply roller  71 B to the developing roller  71 A and carried on the developing roller  71 A. 
     A toner storage portion  72  is disposed in front of the frontmost developing device  71  among the developing devices  71 . The toner storage portion  72  is disposed at a position corresponding to the first cleaning roller  63 . The toner storage portion  72  is configured to store the toner removed by the first cleaning roller  63 . More specifically, the toner storage portion  72  includes a second cleaning roller  72 A contacting the first cleaning roller  63 . The toner storage portion  72  is configured to store the toner scraped off the first cleaning roller  63  by the second cleaning roller  72 A. 
     The scanner unit  8  is disposed at a lower portion of the main casing  2 . The scanner unit  8  includes a laser emitting section, a polygon mirror, a lens, and a reflecting mirror, all of which are not depicted in the drawings. In the scanner unit  8 , the laser beams travel along paths shown by the two-dot chain lines in  FIG.  1    and scan at high speed across respective surfaces of the photosensitive drums  61 . 
     The belt unit  9  mainly includes, in a belt supporting frame  90  that constitutes an outer frame of the unit  9 , an intermediate transfer belt  91 , four first transfer rollers  92 , a second transfer roller  93 , a drive roller  94 , and a follower roller  95 . 
     The intermediate transfer belt  91  is an endless belt. The intermediate transfer belt  91  is wound around the drive roller  94  and the follower roller  95  that are spaced apart in the front-rear direction and disposed parallel to each other. The photosensitive drums  61  and the first cleaning rollers  63  oppose and contact a lower portion of an outer peripheral surface of the intermediate transfer belt  9 . The second transfer roller  93  opposes and contacts a rear portion of the outer peripheral surface of the intermediate transfer belt  9 , e.g., a rear end portion of the belt unit  9 . 
     Each of the first transfer rollers  92  contacts an inner peripheral surface of the intermediate transfer belt  91 . Each of the first transfer rollers  92  opposes the respective photosensitive drum  61  to hold the intermediate transfer belt  91  therebetween. The second transfer roller  93  opposes the drive roller  94  to hold the intermediate transfer belt  91  therebetween. A transfer bias is applied to the first transfer rollers  92  and the second transfer roller  93  during a transfer operation. 
     The fixing unit  10  is disposed opposite to the developing device unit  7  relative to the drum unit  6 , e.g., above the drum unit  6 , at a position closer to a rear end portion of the drum unit  6 . 
     The fixing unit  10  mainly includes a heat roller  11  having a known structure and a pressure roller  12  disposed opposite to the heat roller  11  to press the heat roller  11 . 
     In the image forming unit  5  as structured above, each of the chargers  62  uniformly charges a surface of the respective photosensitive drum  61 . Thereafter, the scanner unit  8  exposes the surfaces of the respective photosensitive drums  61  to light, so that the potential of the exposed portions is lowered. Electrostatic latent images are formed based on image data on the surfaces of the respective photosensitive drums  61 . 
     Then, toner carried on each of the developing rollers  71 A is supplied to electrostatic latent images formed on the respective photosensitive drums  61 . Thus, the toner is selectively carried on the photosensitive drums  61  and the electrostatic latent images are developed into visible toner images. 
     The toner images formed on the respective photosensitive drums  61  are sequentially transferred to the intermediate transfer belt  91  so as to be superimposed one on another by virtue of the transfer bias applied to the respective first transfer rollers  92 . When the sheet P supplied to the image forming unit  5  passes between the intermediate transfer belt  91  and the second transfer roller  93  to which transfer bias is applied, the full-color toner images on the intermediate transfer belt  91  are transferred on the sheet P. 
     The sheet P having the toner images transferred thereon is fed to the fixing unit  10 . The toner images are thermally fixed onto the sheet P while the sheet P passes between the heat roller  11  and the pressure roller  12 . The sheet P having the toner image thermally fixed thereon is discharged by discharge rollers  23  onto the discharge tray  22  outside the main casing  2 . The discharge tray  22  is disposed at the upper surface of the main casing  2 , so as not to correspond or respond to the opening and closing movements of the front cover  24 . 
     Next, structures of the belt unit  9 , the drum unit  6  and the developing device unit  7  will be described. 
     Structure of Belt Unit 
     As depicted in  FIG.  2   , the belt unit  9  is supported by movable members  100  disposed opposite to each other at the right and left sides of the intermediate transfer belt  91 . 
     Each of the movable members  100  extends in the front-rear direction. Each of the movable members  100  is disposed at a respective one of right and left side frames  110  of the main casing  2 . 
     Each of the movable members  100  includes a front opening  101 A disposed at a position corresponding to a rotation shaft  95 A of the follower roller  95  of the belt unit  9  and a rear opening  101 B disposed at a position corresponding to a rotation shaft  94 A of the drive roller  94 . 
     The front opening  101 A is formed into an elongated hole extending in the front-rear direction. The front opening  101 A movably supports the rotation shaft  95 A of the follower roller  95 . The rear opening  101 B is formed into an elongated hole extending in the front-rear direction. The rear opening  101 B movably supports the rotation shaft  94 A of the drive roller  94 . 
     The movable members  100  are disposed such that a front end portion of the front opening  101 A contacts the rotation shaft  95 A of the follower roller  95  and a front end portion of the rear opening  101 B contacts the rotation shaft  94 A of the drive roller  94  when the front cover  24  is closed. 
     Each of the movable members  100  includes a guide portion  102  disposed below the front opening  101 A and the rear opening  101 B. The guide portion  102  is a groove extending in the front-rear direction. A front portion of the guide portion  102  is open. 
     Each of the movable members  100  includes a shaft portion  103  extending outward (e.g., toward an exterior of the main casing  2 ) in the left-right direction below a rear portion of the respective guide portion  102 . The shaft portion  103  is supported by an elongated hole  111  formed on a respective one of side frames  110  disposed at right and left sides of the main casing  2 . Thus, each of the movable members  100  is configured to pivotally move about the respective shaft portion  103  relative to the corresponding side frame  110 . 
     The elongated hole  111  diagonally extends forwardly and upwardly. The elongated hole  111  movably supports a respective one of the shaft portions  103 . The elongated hole  111  is disposed such that a rear end portion thereof contacts the respective shaft portion  103  when the front cover  24  is closed. Thus, the rearward movements of the movable members  100  are regulated, and the movable members  100  are positioned in place in the main casing  2 . 
     The movable members  100  are coupled to the front cover  24  by respective pivotal members  120  and tension springs  130 . The pivotal lever is an example of a pivotal member  120 . The tension spring  130  is an example of a connection member and an example of a spring. The pivotal member  120  and the tension spring  130  are an example of a coupling mechanism. The coupling mechanism is an example of an interlock mechanism. 
     The pivotal member  120  is configured to pivotally move relative to the main casing  2  about an axis of a pivot shaft  121  supported by the main casing  2 . The pivotal member  120  includes a first coupling portion  122  extending generally rearward from the pivot shaft  121  when the front cover  24  is closed and a second coupling portion  123  extending generally upward from the pivot shaft  121  when the front cover  24  is closed. 
     An end of the first coupling portion  122  is pivotally supported below a front portion of the respective movable member  100 . One end (e.g., the upper end) of the tension spring  130  is fixed to an end of the second coupling portion  123 . 
     The tension spring  130  is configured to expand and contract. The other end (e.g., the lower end) of the tension spring  130  is fixed to the front cover  24 . Thus, each of the tension springs  130  connects the respective second coupling portion  123  and the front cover  24 . As the front cover  24  is opened as depicted in  FIG.  3   , each of the tension springs  130  pulls the respective second coupling portion  123  downward to pivotally move the respective pivotal member  120  counterclockwise in  FIG.  2   . 
     Structure of Drum Unit 
     As depicted in  FIG.  4   , the drum unit  6  includes a drum supporting frame  60  having a frame shape in plane view. The upper end of each of side walls  60 A of the drum supporting frame  60  is provided with a drum rib  60 B extending outward (e.g., toward an exterior of the main casing  2 ) in the left-right direction. The drum rib  60 B is a portion supported by the respective movable member  100 . The guide portion  102  of each of the movable members  100  allows the respective the drum rib  60 B to enter thereinto. The drum unit  6  is configured to be withdrawn through the opening  2 A in a direction in which the photosensitive drums  61  are arranged, while the movement of the drum unit  6  is guided by the guide portions  102 , as depicted in  FIGS.  5  and  6   . 
     As depicted in  FIG.  4   , each of the photosensitive drums  61  is provided in a drum frame  64  pivotally supported by the drum supporting frame  60 . A shaft  61 A is supported by a corresponding one of first shaft holes  60 C formed on a respective one of the side walls  60 A of the drum supporting frame  60 . The first shaft hole  60 C has a circular shape. Each of the photosensitive drums  61  is configured to move vertically relative to the drum supporting frame  60  by the pivotal movements of the respective drum frame  64 . 
     As depicted in  FIGS.  2  and  7   , a positioning member  140  for positioning the photosensitive drums  61  is disposed inwardly of a respective one of the left and right side walls  60 A of the drum supporting frame  60 , e.g., closer to the center of the main casing  2  than the respective left and right side wall  60 A in the right-left direction. The positioning member  140  has a plate shape. Each of the positioning members  140  is fixed at a lower wall  2 B where the scanner unit  8  is disposed in the main casing  2 . 
     The positioning members  140  are disposed at positions corresponding to the right and left ends of the photosensitive drums  61 . Each of the positioning members  140  includes recesses  141  disposed at positions corresponding to the respective photosensitive drums  61 . Each of the recesses  141  is depressed downward. 
     As depicted in  FIG.  4   , a second shaft hole  60 D that supports a shaft  63 A of the first cleaning roller  63  is provided at a respective one of the side walls  60 A of the drum supporting frame  60 . The second shaft hole  60 D is formed into an elongated hole elongated in the vertical direction. Thus, the first cleaning roller  63  is configured to move vertically relative to the drum supporting frame  60 . As will be described in detail, the first cleaning roller  63  is configured to be moved upward to an upper end portion of the second shaft hole  60 D (e.g., as the shaft  63 A is depicted in a solid line in  FIG.  4   ), when the second cleaning roller  72 A contacts the first cleaning roller  63  and to move downward (e.g., as the shaft  63 A is depicted in a two-dot chain line in  FIG.  4   ) when the second cleaning roller  72 A does not contact the first cleaning roller  63 . 
     Structure of Developing Device Unit 
     As depicted in  FIG.  8 A , the developing device unit  7  includes a developing device supporting frame  70 , developing devices  71 , a toner storage portion  72 , and developing device guide members  150  (refer to  FIG.  2   ). 
     The developing device supporting frame  70  has a generally box shape with an upper portion thereof being open. The lower wall of the developing device supporting frame  70  has a plurality of openings  70 D through which the laser beams emitted from the scanner unit  8  pass. 
     The developing device supporting frame  70  has recess-shaped guide grooves  70 B for supporting the developing devices  71 . Each of the guide grooves  70 B is disposed at an inner surface of a respective one of left and right side walls  70 A. The guide groove  70 B extends from the upper end of the respective side wall  70 A diagonally rearward and downward and then rearward. 
     As depicted in  FIG.  8 B , the developing device supporting frame  70  includes a developing device rib  70 C disposed at an outer surface of a respective one of the side walls  70 A. The developing device rib  70 C protrudes outward (e.g., toward an exterior of the main casing  2 ) in the left-right direction and extends in the front-rear direction. 
     As depicted in  FIG.  8 A , the developing device  71  includes a developing device frame  73  provided with, for example, the developing roller  71 A. A pivot shaft  73 A is disposed to the rear of the developing roller  71 A of the developing device frame  73 . Each of the developing devices  71  is mounted to the developing device supporting frame  70  (e.g., positioned in a respective mounted position) by inserting the respective pivot shaft  73 A into a rearmost portion of the corresponding guide groove  70 B. In the mounted position, the developing device  71  is configured to pivot about the corresponding pivot shaft  73 A. 
     A shaft  71 C of each of the developing rollers  71 A protrudes through the corresponding developing device frame  73  outward (e.g., toward an exterior of the main casing  2 ) in the left-right direction. More specifically, as depicted in  FIG.  7   , the shaft  71 C of the developing roller  71 A protrudes outward in the left-right direction such that each of left and right end portions of the shaft  71 C protrudes to the left and right, respectively, relative to a respective one of the left and right side walls  70 A of the developing device supporting frame  70 . 
     As depicted in  FIG.  8 B , the toner storage portion  72  has two elongated holes  72 B, at lower rear end portions of a side surface of the toner storage portion  72 . The toner storage portion  72  is movably supported by the developing device  71  with each of the elongated holes  72 B engaging a respective one of protrusions  71 D formed at lower front portions of the frontmost developing device frame  73 . 
     Two shaft members  72 C protruding outward (e.g., toward an exterior of the main casing  2 ) in the left-right direction are provided at a side surface of the toner storage portion  72 . Each of the shaft members  72 C is provided such that each end portion of the shaft member  72 C in the left-right direction extends to a position corresponding to a respective end portion of the shaft  71 C of the developing roller  71 A in the left-right direction. 
     As depicted in  FIG.  7   , the developing device guide members  150  are supported by the respective positioning members  140  from an outside of the developing device guide members  150  in the left-right direction, e.g., from a side of the developing device guide member  150  closer to an exterior of the main casing  2  in the left-right direction. Each of the developing device guide members  150  extends in the front-rear direction. As depicted in  FIG.  2   , each of the developing device guide member  150  includes a developing device guide portion  151  that supports the developing device unit  7 . 
     The developing device guide portions  151  has a groove extending in the front-rear direction. A front portion of the developing device guide portion  151  is open. As depicted in  FIG.  9   , the developing device guide portion  151  is formed to allow the corresponding developing device rib  70 C to pass therethrough. As the movement of the developing device unit  7  is guided by the developing device guide portions  151 , the developing device unit  7  may be withdrawn through the opening  2 A in the front-rear direction (e.g., in which the developing rollers  71 A are arranged). 
     Each of the developing device guide members  150  includes a developing roller supporting portion  152  configured to press the developing rollers  71 A against the corresponding photosensitive drums  61  when the front cover  24  is closed, spring members  153  and link members  154 . 
     The developing roller supporting portion  152  extends in the front-rear direction as depicted in  FIGS.  2  and  10 A . The developing roller supporting portion  152  is positioned below the developing rollers  71 A. Each of the developing roller supporting portions  152  is configured such that a tip thereof contacts a respective one of protruding portions  24 B protruding from the rear surface of the front cover  24 , when the front cover  24  is closed. 
     The link members  154  link each of the developing device guide members  150  and the respective developing roller supporting portion  152 . The link member  154  is disposed in front of five spring members  153  (described below), and behind the rearmost spring member  153 , so that the six link members  154  are provided for each developing device guide member  150  and the respective developing roller supporting portion  152 . One end (e.g., the lower end) of each of the link members  154  is pivotally coupled to the respective developing device guide members  150 . The other end (e.g., the upper end) of each of the link members  154  is pivotally coupled to the respective developing roller supporting portions  152 . Each of the developing roller supporting portions  152  is configured to pivotally move relative to the respective developing device guide member  150  as each of the link members  154  pivot about one end thereof. 
     Each of the spring members  153  protrudes upward from a portion of the developing roller supporting portion  152 . A protruding portion of the spring member  153  extends in the front-rear direction. The spring member  153  is disposed in corresponding with a respective one of the four developing rollers  71 A and one of the shaft members  72 C of the toner storage portion  72 , so that the five spring members  153  are provided for each of the developing roller supporting portions  152 . 
     Each of the spring members  153  is configured to contact a respective one of the shafts  71 C of the developing rollers  71 A and the shaft member  72 C of the toner storage portion  72  when the front cover  24  is closed. Each of the spring members  153  is configured to bias a respective one of the developing devices  71  and the toner storage portion  72  upward as each of the spring members  153  contact a respective one of the shafts  71 C and the shaft member  72 C. Thus, the developing roller supporting portions  152  press the developing rollers  71 A toward the corresponding photosensitive drums  61  and press the second cleaning roller  72 A toward the first cleaning roller  63 . 
     As depicted in  FIG.  10 A , when the front cover  24  is closed, a tip of the developing roller supporting portion  152  is in contact with the protruding portion  24 B, and each of the link members  154  extends vertically. As depicted in  FIG.  10 B , when the front cover  24  is open, the tip of the developing roller supporting portion  152  does not contact the protruding portion  24 B, and the developing roller supporting portion  152  is moved downward by the weights of the developing devices  71  and downward reaction force of the spring members  153 . 
     Effects of the color multifunction device  1  as structured above will be described. When the front cover  24  is closed as depicted in  FIG.  1   , the belt unit  9  and the drum unit  6  are disposed at positions to place the photosensitive drums  61  closer to the respective developing rollers  71 A. As the front cover  24  is opened as depicted in  FIG.  5   , the pivotal members  120  pivot, so that an end of each of the first coupling portions  122  is diagonally moved forwardly and upwardly. Accordingly, as a front end portion of each of the movable members  100  is raised while pivoting about the respective shaft portion  103 , each of the shaft portions  103  moves from a rear end portion of the respective elongated hole  111  to a position to contact a front end portion of the respective elongated hole  111 . In other words, the movable members  100  move, in response to the opening and closing movements of the front cover  24 , from an accommodated position (e.g., a position depicted in  FIG.  2   ) to a moved position (e.g., a position depicted in  FIG.  3   ). 
     As depicted in  FIGS.  2  and  3   , as the movable members  100  move from the accommodated position to the moved position, the rotation shaft  95 A of the follower roller  95  moves from a position where the rotation shaft  95 A is in contact with front end portions of the front openings  101 A to a position where the rotation shaft  95 A contacts rear end portions of the front openings  101 A, and the rotation shaft  94 A of the drive roller  94  moves from a position where the rotation shaft  94 A is in contact with front end portions of the rear openings  101 B to a position where the rotation shaft  94 A contacts a rear end portions of the rear openings  101 B. In other words, the belt unit  9  moves relative to the movable members  100 , so that the first transfer rollers  92  are disposed at positions shifted from positions to oppose the corresponding photosensitive drums  61 . 
     At this time, the belt unit  9  diagonally moves forwardly and upwardly together with the movable members  100 , and the drive roller  94  moves away from the second transfer roller  93 . In other words, the belt unit  9  moves from a first position (e.g., a position depicted in  FIG.  2   ) to a second position (e.g., a position depicted in  FIG.  3   ) higher than the first position, by the movement of the movable members  100  from the accommodated position to the moved position. 
     As depicted in  FIG.  5   , as the drum ribs  60 B are supported by the corresponding movable members  100 , the drum unit  6  moves from a third position (e.g., a position depicted in  FIG.  1   ) where the photosensitive drums  61  are brought closer to the respective developing rollers  71 A, to a fourth position (e.g., a position depicted in  FIG.  5   ), which is higher than the third position, and where the photosensitive drums  61  moves away from the respective developing rollers  71 A, by the movement of the movable members  100  from the accommodated position to the moved position. In other words, when the front cover  24  moves from the closed position to the open position, the belt unit  9  moves from the first position to the second position and the drum unit  6  moves from the third position to the fourth position. When the front cover  24  moves from the open position to the closed position, the belt unit  9  moves from the second position to the first position and the drum unit  6  moves from fourth position to the third position. Thus, the drum unit  6  is configured to be disposed at a position not to interfere with the developing device unit  7 . 
     As the movable members  100  supporting the belt unit  9  and the drum unit  6  move upward and downward in response to the opening and closing movements of the front cover  24 , the belt unit  9  and the drum unit  6  may be readily moved. 
     As depicted in  FIG.  9   , the developing device unit  7  is withdrawn through the opening  2 A along the developing device guide portions  151  of the developing device guide members  150 . Thus, the developing device unit  7  may be readily withdrawn through the opening  2 A by just opening the front cover  24  in the illustrative embodiment. Therefore, an operation of withdrawing the developing device unit  7  may be facilitated. 
     As depicted in  FIG.  6   , as the front cover  24  is opened, the drum unit  6  may be withdrawn through the opening  2 A along the guide portions  102  of the movable members  100 . Therefore, both the developing device unit  7  and the drum unit  6  may be withdrawn through the opening  2 A by just opening the front cover  24 . 
     Front end portions of the movable members  100  are raised by the first coupling portions  122 . An amount of front end portions of the movable members  100  (closer to the opening  2 A) moved in the vertical direction (e.g., top-bottom direction) when the movable members  100  move from the accommodated position to the moved position is greater than that of rear end portions of the movable members  100  (e.g., farther from the opening  2 A) moved in the vertical direction when the movable members  100  move from the accommodated position to the moved position. In other words, the drum unit  6  is positioned higher toward a front portion thereof, so that the developing device unit  7  may be readily withdrawn. As a movement amount of a rear portion of the movable member  100  in the vertical direction is smaller, interference of the belt unit  9  with a member or component disposed above a rear end portion of the belt unit  9  (e.g., the fixing unit  10 ) may be prevented or reduced. 
     When the drum unit  6  is in the third position, the photosensitive drums  61  are disposed at the respective the recesses  141  of the positioning members  140 , and the photosensitive drums  61  are raised (e.g., as the shafts  61 A are depicted in  FIG.  4    by solid lines). When the drum unit  6  is in the fourth position, the photosensitive drums  61  move away from the positioning members  140  and move downward (e.g., as the shafts  61 A are depicted in  FIG.  4    by two-dot chain lines). The shafts  61 A contact the lower edges of the respective first shaft holes  60 C. 
     In other words, the photosensitive drums  61  move down relative to the drum supporting frame  60 , when the drum supporting frames  60  are raised. When the drum unit  6  is in the fourth position to withdraw the drum unit  6 , interference of the photosensitive drums  61  with the belt unit  9  may be prevented or reduced. When the drum unit  6  is withdrawn, interference of the photosensitive drums  61  with the belt unit  9  may further be prevented or reduced as the first transfer rollers  92  are shifted from positions to oppose the respective photosensitive drums  61 . 
     As depicted in  FIGS.  10 A and  10 B , each of the developing roller supporting portions  152  moves upward and downward in response to the opening and closing movements of the front cover  24 . Therefore, the developing device unit  7  moves between a developing position (e.g., a position depicted in  FIG.  10 A ) where the developing rollers  71 A oppose the respective photosensitive drums  61  when the front cover  24  is closed, and a retracted position (e.g., a position depicted in  FIG.  10 B ) lower than the developing position when the front cover  24  is opened. Therefore, when the developing device unit  7  is withdrawn, interference with the drum unit  6  disposed above the developing device unit  7  may further be prevented or reduced. 
     When the developing device unit  7  is raised to the developing position, the shaft member  72 C of the toner storage portion  72  is raised by the spring members  153  of the developing roller supporting portions  152  (refer to  FIG.  10 A ). In other words, the toner storage portion  72  moves, in response to the movement of the developing device unit  7 , between a position in which the second cleaning roller  72 A contacts the first cleaning roller  63  (e.g., a position depicted in  FIG.  10 A ) and a position in which the second cleaning roller  72 A does not contact the first cleaning roller  63  (e.g., a position depicted in  FIG.  10 B ) and below the position in which the second cleaning roller  72 A contacts the first cleaning roller  63 . 
     Therefore, when the developing device unit  7  is withdrawn, interference of the second cleaning roller  72 A with the first cleaning roller  63  may be prevented or reduced. When the drum unit  6  is in the fourth position, the first cleaning roller  63  is lowered. Accordingly, interference of the first cleaning roller  63  with the belt unit  9  when the drum unit  6  is withdrawn may be prevented or reduced. 
     As the pivotal members  120  and the tension springs  130  couple or connect the movable members  100  and the front cover  24 , the opening and closing movements of the front cover  24  may be readily linked with the movements of the movable members  100 . 
     The pivot shaft  24 A of the front cover  24  is disposed below the developing device unit  7 . Therefore, the developing device unit  7  may be withdrawn without interfering the pivot shaft  24 A. When the developing device unit  7  is withdrawn, the front cover  24  is positioned below the developing device unit  7 . Therefore the front cover  24  might not interfere with the developing device unit  7 . 
     The tension springs  130  pull the second coupling portions  123  of the pivotal members  120  downward when the front cover  24  is opened, so that the first coupling portions  122  of the pivotal members  120  raise the movable members  100 . In other words, the pivotal members  120  convert downward force from the front cover  24  via the tension springs  130  into a force to raise the movable members  100 . Thus, the movements of the movable members  100  may be readily linked to the opening and closing movements of the front cover  24 . The movable members  100  may be raised with downward force which is relatively less force required by a user. 
     While the disclosure has been described in detail with reference to the specific embodiment thereof, this is merely an example, and various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure. 
     In the above-described illustrative embodiment, the belt unit  9  and the drum unit  6  are configured to move together, via the movable members  100 . However, the disclosure is not limited thereto. The belt unit  9  and the drum unit  6  may be configured to independently move in response to the opening and closing movements of the front cover  24 . 
     In the above-described illustrative embodiment, the pivotal member  120  includes the first coupling portion  122  and the second coupling portion  123 . However, the disclosure is not limited thereto. Components of a pivotal member may be changed as necessary according to illustrative embodiments. 
     In the above-described illustrative embodiment, the tension spring  130  is an example of the connection member. However, the disclosure is not limited thereto. An expandable member other than the tension spring  130  may be used. 
     In the above-described illustrative embodiment, the drum unit  6  is configured to be withdrawn through the opening  2 A. However, the disclosure is not limited thereto. The drum unit  6  may be configured so as not to be withdrawn. 
     In the above-described illustrative embodiment, a movement amount of a front end portion of the movable member  100  is greater than that of a rear end portion of the movable member  100 . However, the disclosure is not limited thereto. For example, movement amounts of the front end portion and the rear end portion of the movable member  100  may be the same. 
     In the above-described illustrative embodiment, the positioning members  140  are provided to position the photosensitive drums  61 . However, the disclosure is not limited thereto. The positioning members  140  may be omitted. 
     In the above-described illustrative embodiment, the photosensitive drums  61  are configured to move relative to the drum supporting frame  60 . The developing devices  71  are configured to move relative to the developing device supporting frame  70 . However, the disclosure is not limited thereto. The photosensitive drums  61  and the developing devices  71  may be configured so as not to move. 
     In the above-described illustrative embodiment, the toner storage portion  72  is provided in the developing device  71 . However, the disclosure is not limited thereto. The toner storage portion  72  may be omitted or a toner storage portion may be provided in a belt unit. 
     In the above-described illustrative embodiment, the color multifunction device  1  is an example of the image forming apparatus. However, the disclosure is not limited thereto. The disclosure may be applied to a printer that does not include, for example, a copying device or the flatbed scanner  3 . In the image forming apparatus of the disclosure, photosensitive drums may be exposed with light from, for example, light-emitting diode (LED), electroluminescence (EL) element, and florescent materials, other than laser beams. 
     In the above-described illustrative embodiment, the interlock mechanism is provided to couple the movable members  100  to the front cover  24  mechanically. However, the disclosure is not limited thereto. The interlock mechanism may include electrical elements, such as a sensor, a processor and a motor, such that the movable members  100  is moved in response to a movement of the front cover  24 .